A monoclonal antibody recognizes undifferentiation-specific carbohydrate moieties expressed on cell surface of the human dental pulp cells.

PubMed

Kang, Kyung-Jung; Ko, Seon-Yle; Ryu, Chun-Jeih; Jang, Young-Joo

2017-05-01

Human dental pulp cells are obtained from dental pulp tissue, and have the ability to form dentin and a pulp-like complex. Although adult stem cells have been identified from the primary culture by using specific cell surface markers, the identity of surface markers for the purification of stem cells within the dental pulp population are still unclear. Previously, we had constructed monoclonal antibodies against the undifferentiated cell-specific surface markers of human dental pulp cells (hDPCs) by performing decoy immunization. Among them, a monoclonal antibody against the cell surface antigen of the undifferentiated hDPCs (named UPSA-1) was purified and its heavy and light chain consensus regions were analyzed. The cell surface binding affinity of UPSA-1 mAb on the undifferentiated hDPCs was stronger than that on the differentiated cells. When tunicamycin was applied to hDPSCs during culture, the cell surface binding affinity of the antibody was dramatically decreased, and dentinogenic differentiation was reduced. The purified UPSA-1 antigen band resulting from immunoprecipitation disappeared or shifted down on the SDS-PAGE by deglycosylation. These data suggested that glycosylation on the cell surface might be a marker of an undifferentiated state, and that UPSA-1 mAb might be useful for identifying the carbohydrate moiety on the cell surface of undifferentiated pulp cells. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Concurrent detection of secreted products from human lymphocytes by microengraving: cytokines and antigen-reactive antibodies

PubMed Central

Bradshaw, Elizabeth M.; Kent, Sally C.; Tripuraneni, Vinay; Orban, Tihamer; Ploegh, Hidde L.; Hafler, David A.; Love, J. Christopher

2008-01-01

Cell surface determinants, cytokines and antibodies secreted by hematopoietic cells are used to classify their lineage and function. Currently available techniques are unable to elucidate multiple secreted proteins while also assigning phenotypic surface-displayed markers to the individual living cells. Here, a soft lithographic method, microengraving, was adapted for the multiplexed interrogation of populations of individual human peripheral blood mononuclear cells for secreted cytokines (IFN-γ and IL-6), antigen-specific antibodies, and lineage-specific surface-expressed markers. Application of the method to a clinical sample from a recent onset Type 1 diabetic subject with a positive titer of anti-insulin antibodies showed that ~0.58% of circulating CD19+ B cells secreted proinsulin-reactive antibodies of the IgG isotype and 2–3% of circulating cells secreted IL-6. These data demonstrate the utility of microengraving for interrogating multiple phenotypes of single human cells concurrently and for detecting rare populations of cells by their secreted products. PMID:18675591

Mechanisms of red blood cells agglutination in antibody-treated paper.

PubMed

Jarujamrus, Purim; Tian, Junfei; Li, Xu; Siripinyanond, Atitaya; Shiowatana, Juwadee; Shen, Wei

2012-05-07

Recent reports on using bio-active paper and bio-active thread to determine human blood type have shown a tremendous potential of using these low-cost materials to build bio-sensors for blood diagnosis. In this work we focus on understanding the mechanisms of red blood cell agglutination in the antibody-loaded paper. We semi-quantitatively evaluate the percentage of antibody molecules that are adsorbed on cellulose fibres and can potentially immobilize red blood cells on the fibre surface, and the percentage of the molecules that can desorb from the cellulose fibre surface into the blood sample and cause haemagglutination reaction in the bulk of a blood sample. Our results show that 34 to 42% of antibody molecules in the papers treated with commercial blood grouping antibodies can desorb from the fibre surface. When specific antibody molecules are released into the blood sample via desorption, haemagglutination reaction occurs in the blood sample. The reaction bridges the red cells in the blood sample bulk to the layer of red cells immobilized on the fibre surface by the adsorbed antibody molecules. The desorbed antibody also causes agglutinated lumps of red blood cells to form. These lumps cannot pass through the pores of the filter paper. The immobilization and filtration of agglutinated red cells give reproducible identification of positive haemagglutination reaction. Results from this study provide information for designing new bio-active paper-based devices for human blood typing with improved sensitivity and specificity.

Analysis of the 3D structure og agglutinated erythrocyte using CellScan and confocal microscopy: characterization by FLIM-FRET

NASA Astrophysics Data System (ADS)

Riquelme, Bibiana D.; Dumas, Dominique; Valverde de Rasia, Juana; Rasia, Rodolfo J.; Stoltz, Jean Francois

2003-10-01

We report the adhesion of human erythrocyte membranes mediated by monoclonal antibodies anti-glycophorin. The distribution of the linked antibodies on membrane was identified with selective fluorescence labels. To analyze the antibody distribution on interfacial region between two cells agglutinated and on its surface, three types of fluorescence marked strategy were evaluated. The 3D images were obtained in a CellScan and Confocal Laser Scanning Microscopy CLSM. We considered the FRET signal to characterize the agglutination of Red Blood Cells (RBC) by specific monoclonal antibodies (anti-glycophorin A or B). The fluorescence labeling demonstrated that distribution of antibody on erythrocyte membranes is not homogeneous. The fluorescence intensity on contact region in the agglutinated is bigger than the intensity on exterior surface. Tentatively, we interpreted these intensity differences in terms of the mobility of antibody linked to the glycocalix on cell surface. Such mobility has a large consequence in the morphology of cellular agglutinated.

Antibody Therapeutics in Oncology.

PubMed

Wold, Erik D; Smider, Vaughn V; Felding, Brunhilde H

2016-03-01

One of the newer classes of targeted cancer therapeutics is monoclonal antibodies. Monoclonal antibody therapeutics are a successful and rapidly expanding drug class due to their high specificity, activity, favourable pharmacokinetics, and standardized manufacturing processes. Antibodies are capable of recruiting the immune system to attack cancer cells through complement-dependent cytotoxicity or antibody dependent cellular cytotoxicity. In an ideal scenario the initial tumor cell destruction induced by administration of a therapeutic antibody can result in uptake of tumor associated antigens by antigen-presenting cells, establishing a prolonged memory effect. Mechanisms of direct tumor cell killing by antibodies include antibody recognition of cell surface bound enzymes to neutralize enzyme activity and signaling, or induction of receptor agonist or antagonist activity. Both approaches result in cellular apoptosis. In another and very direct approach, antibodies are used to deliver drugs to target cells and cause cell death. Such antibody drug conjugates (ADCs) direct cytotoxic compounds to tumor cells, after selective binding to cell surface antigens, internalization, and intracellular drug release. Efficacy and safety of ADCs for cancer therapy has recently been greatly advanced based on innovative approaches for site-specific drug conjugation to the antibody structure. This technology enabled rational optimization of function and pharmacokinetics of the resulting conjugates, and is now beginning to yield therapeutics with defined, uniform molecular characteristics, and unprecedented promise to advance cancer treatment.

Immunization with SV40-transformed cells yields mainly MHC-restricted monoclonal antibodies

PubMed Central

1986-01-01

Recognition of antigens on cell surfaces only in the context of the MHC- encoded alloantigens of the presenting cell (self + X) has classically been considered the province of T cells. However, evidence from several sources has indicated that B cells and antibodies can exhibit self + X- restricted recognition as well. This report concerns the mAb response to SV40-transformed H-2b fibroblast cell lines. The specificities of the antibodies obtained have been analyzed for binding to a panel of SV40-transformed H-2-syngeneic, H-2-allogeneic, and H-2b mutant fibroblast cell lines, as well as cell lines not bearing cell surface SV40 transformation-associated antigens. A large proportion of primary C57BL/6 (71%) and BALB/c (68%) splenic B cells responding to in vitro stimulation with SV40-transformed H-2b cells recognize cell surface antigens associated with SV40 transformation only when coexpressed with MHC antigens of the immunizing cell, particularly the Kb molecule, on transformed cells. To extensively define the nature of antigen recognition by these antibodies, we have generated and characterized nine hybridoma antibodies specific for SV40-transformed H-2-syngeneic cell lines. Seven of these hybridoma antibodies recognize SV40- associated transformation antigens in the context of H-2b molecules. Six of these are restricted by the Kb molecule and discriminate among a panel of SV40-transformed Kb mutant cell lines, thus confirming the participation of class I MHC-encoded molecules in the recognition by B cells of cell surface antigens. PMID:3014034

Immunopathology of autoantibody-associated encephalitides: clues for pathogenesis.

PubMed

Bien, Christian G; Vincent, Angela; Barnett, Michael H; Becker, Albert J; Blümcke, Ingmar; Graus, Francesc; Jellinger, Kurt A; Reuss, David E; Ribalta, Teresa; Schlegel, Jürgen; Sutton, Ian; Lassmann, Hans; Bauer, Jan

2012-05-01

Classical paraneoplastic encephalitis syndromes with 'onconeural' antibodies directed to intracellular antigens, and the recently described paraneoplastic or non-paraneoplastic encephalitides and antibodies against both neural surface antigens (voltage-gated potassium channel-complexes, N-methyl-d-aspartate receptors) and intracellular antigens (glutamic acid decarboxylase-65), constitute an increasingly recognized group of immune-mediated brain diseases. Evidence for specific immune mechanisms, however, is scarce. Here, we report qualitative and quantitative immunopathology in brain tissue (biopsy or autopsy material) of 17 cases with encephalitis and antibodies to either intracellular (Hu, Ma2, glutamic acid decarboxylase) or surface antigenic targets (voltage-gated potassium channel-complex or N-methyl-d-aspartate receptors). We hypothesized that the encephalitides with antibodies against intracellular antigens (intracellular antigen-onconeural and intracellular antigen-glutamic acid decarboxylase groups) would show neurodegeneration mediated by T cell cytotoxicity and the encephalitides with antibodies against surface antigens would be antibody-mediated and would show less T cell involvement. We found a higher CD8/CD3 ratio and more frequent appositions of granzyme-B(+) cytotoxic T cells to neurons, with associated neuronal loss, in the intracellular antigen-onconeural group (anti-Hu and anti-Ma2 cases) compared to the patients with surface antigens (anti-N-methyl-d-aspartate receptors and anti-voltage-gated potassium channel complex cases). One of the glutamic acid decarboxylase antibody encephalitis cases (intracellular antigen-glutamic acid decarboxylase group) showed multiple appositions of GrB-positive T cells to neurons. Generally, however, the glutamic acid decarboxylase antibody cases showed less intense inflammation and also had relatively low CD8/CD3 ratios compared with the intracellular antigen-onconeural cases. Conversely, we found complement C9neo deposition on neurons associated with acute neuronal cell death in the surface antigen group only, specifically in the voltage-gated potassium channel-complex antibody patients. N-methyl-d-aspartate receptors-antibody cases showed no evidence of antibody and complement-mediated tissue injury and were distinguished from all other encephalitides by the absence of clear neuronal pathology and a low density of inflammatory cells. Although tissue samples varied in location and in the stage of disease, our findings strongly support a central role for T cell-mediated neuronal cytotoxicity in encephalitides with antibodies against intracellular antigens. In voltage-gated potassium channel-complex encephalitis, a subset of the surface antigen antibody encephalitides, an antibody- and complement-mediated immune response appears to be responsible for neuronal loss and cerebral atrophy; the apparent absence of these mechanisms in N-methyl-d-aspartate receptors antibody encephalitis is intriguing and requires further study.

Expression of Receptors for Tetanus Toxin and Monoclonal Antibody A2B5 by Pancreatic Islet Cells

NASA Astrophysics Data System (ADS)

Eisenbarth, G. S.; Shimizu, K.; Bowring, M. A.; Wells, S.

1982-08-01

Studies of the reaction of antibody A2B5 and tetanus toxin with pancreatic islet cells, islet cell tumors, and other human amine precursor uptake and decarboxylation (APUD) tumors are described. By indirect immunofluorescence, antibody A2B5 and tetanus toxin were shown to specifically bind to the plasma membrane of human, rat, chicken, and mouse islet cells. The binding of antibody A2B5 to the cell surface of living islet cells has allowed isolation of these cells from a suspension of pancreatic cells by using a fluorescence-activated cell sorter. In studies designed to determine whether tetanus toxin and antibody A2B5 bound to the same surface antigen, A2B5 and tetanus toxin did not compete for binding to normal islet cells, a human islet cell tumor, or a rat islet cell tumor. In addition to binding to islet cell tumors, antibody A2B5 reacts with frozen sections, isolated cells, and cell lines of neural, neural crest, and APUD origin.

Immunocytochemistry of cell surface heparan sulfate proteoglycan in mouse tissues. A light and electron microscopic study.

PubMed

Hayashi, K; Hayashi, M; Jalkanen, M; Firestone, J H; Trelstad, R L; Bernfield, M

1987-10-01

The core protein of the proteoglycan at the cell surface of NMuMG mouse mammary epithelial cells bears both heparan and chondroitin sulfate chains and is recognized by the monoclonal antibody 281-2. Using this antibody and the peroxidase-antiperoxidase staining technique in adult mouse tissues, we found that the antibody recognizes the antigen in a highly restricted distribution, staining a variety of epithelial cells but no cells derived from embryonic mesoderm or neural crest. The antibody fails to stain any stromal (mesenchymal) or neuronal cells, with the exception of plasma cells and Leydig cells. Squamous and transitional epithelia stain intensely over their entire surfaces, whereas cuboidal and columnar epithelia stain moderately and only at the lateral surface of the basal cells. Within squamous and transitional epithelial tissues that undergo physiological regeneration (e.g., epidermis), the most superficial and differentiated cell types fail to stain. Within glandular and branched epithelia (e.g., pancreas), the secretory alveolar cells fail to stain. When evaluated by electron microscopy, granular deposits of stain are seen on the plasma membrane, especially on lateral surfaces, but none are noted within the cells or the basement membrane. These results indicate that in adult tissues the core protein of this heparan sulfate-rich proteoglycan is expressed almost exclusively at epithelial cell surfaces. Expression appears to be lost as the cells become either mature or highly differentiated.

Highly multiplexed and quantitative cell-surface protein profiling using genetically barcoded antibodies.

PubMed

Pollock, Samuel B; Hu, Amy; Mou, Yun; Martinko, Alexander J; Julien, Olivier; Hornsby, Michael; Ploder, Lynda; Adams, Jarrett J; Geng, Huimin; Müschen, Markus; Sidhu, Sachdev S; Moffat, Jason; Wells, James A

2018-03-13

Human cells express thousands of different surface proteins that can be used for cell classification, or to distinguish healthy and disease conditions. A method capable of profiling a substantial fraction of the surface proteome simultaneously and inexpensively would enable more accurate and complete classification of cell states. We present a highly multiplexed and quantitative surface proteomic method using genetically barcoded antibodies called phage-antibody next-generation sequencing (PhaNGS). Using 144 preselected antibodies displayed on filamentous phage (Fab-phage) against 44 receptor targets, we assess changes in B cell surface proteins after the development of drug resistance in a patient with acute lymphoblastic leukemia (ALL) and in adaptation to oncogene expression in a Myc-inducible Burkitt lymphoma model. We further show PhaNGS can be applied at the single-cell level. Our results reveal that a common set of proteins including FLT3, NCR3LG1, and ROR1 dominate the response to similar oncogenic perturbations in B cells. Linking high-affinity, selective, genetically encoded binders to NGS enables direct and highly multiplexed protein detection, comparable to RNA-sequencing for mRNA. PhaNGS has the potential to profile a substantial fraction of the surface proteome simultaneously and inexpensively to enable more accurate and complete classification of cell states. Copyright © 2018 the Author(s). Published by PNAS.

Combining Phage and Yeast Cell Surface Antibody Display to Identify Novel Cell Type-Selective Internalizing Human Monoclonal Antibodies.

PubMed

Bidlingmaier, Scott; Su, Yang; Liu, Bin

2015-01-01

Using phage antibody display, large libraries can be generated and screened to identify monoclonal antibodies with affinity for target antigens. However, while library size and diversity is an advantage of the phage display method, there is limited ability to quantitatively enrich for specific binding properties such as affinity. One way of overcoming this limitation is to combine the scale of phage display selections with the flexibility and quantitativeness of FACS-based yeast surface display selections. In this chapter we describe protocols for generating yeast surface antibody display libraries using phage antibody display selection outputs as starting material and FACS-based enrichment of target antigen-binding clones from these libraries. These methods should be widely applicable for the identification of monoclonal antibodies with specific binding properties.

Engineering chimeric human and mouse major histocompatibility complex (MHC) class I tetramers for the production of T-cell receptor (TCR) mimic antibodies

PubMed Central

Bentley, Carol; Yates, Jenna; Salimi, Maryam; Greig, Jenny; Wiblin, Sarah; Hassanali, Tasneem; Banham, Alison H.

2017-01-01

Therapeutic monoclonal antibodies targeting cell surface or secreted antigens are among the most effective classes of novel immunotherapies. However, the majority of human proteins and established cancer biomarkers are intracellular. Peptides derived from these intracellular proteins are presented on the cell surface by major histocompatibility complex class I (MHC-I) and can be targeted by a novel class of T-cell receptor mimic (TCRm) antibodies that recognise similar epitopes to T-cell receptors. Humoural immune responses to MHC-I tetramers rarely generate TCRm antibodies and many antibodies recognise the α3 domain of MHC-I and β2 microglobulin (β2m) that are not directly involved in presenting the target peptide. Here we describe the production of functional chimeric human-murine HLA-A2-H2Dd tetramers and modifications that increase their bacterial expression and refolding efficiency. These chimeric tetramers were successfully used to generate TCRm antibodies against two epitopes derived from wild type tumour suppressor p53 (RMPEAAPPV and GLAPPQHLIRV) that have been used in vaccination studies. Immunisation with chimeric tetramers yielded no antibodies recognising the human α3 domain and β2m and generated TCRm antibodies capable of specifically recognising the target peptide/MHC-I complex in fully human tetramers and on the cell surface of peptide pulsed T2 cells. Chimeric tetramers represent novel immunogens for TCRm antibody production and may also improve the yield of tetramers for groups using these reagents to monitor CD8 T-cell immune responses in HLA-A2 transgenic mouse models of immunotherapy. PMID:28448627

CELL SURFACE IMMUNOGLOBULIN

PubMed Central

Vitetta, Ellen S.; Uhr, Jonathan W.

1974-01-01

A new method for the detection of cell surface immunoglobulin labeled with isotopic precursors is described. The method consists of the aggregation of surface Ig on cells with specific antibody (heterologous) and the subsequent removal of antigen-antibody complexes by the combination of high speed centrifugation and immunoprecipitation of remaining soluble complexes using antibody to the heterologous Ig. Using this method, the kinetics of appearance of cell surface Ig and its turnover were studied in murine splenocytes. The results suggest that cell surface Ig is synthesized and transported in the same manner as secretory Ig rather than being synthesized on the plasma membrane. The turnover of intracellular and cell surface Ig in lymphocytes is slow. In contrast, intracellular Ig in plasma cells is rapidly secreted and usually without a cell surface phase. Cell surface Ig was shown to be radiolabeled with [3H]glucosamine, -galactose, and -fucose. The proportion of cell surface to intracellular (nonsurface) Ig labeled with these precursors suggests the same sequence of addition of sugars to Ig destined to be on the surface of lymphocytes as with Ig which will be secreted by plasma cells. Results with this new method also confirm earlier conclusions based on experiments using cell surface iodination: 8S IgM is the predominant Ig on the surface of murine splenocytes and the molecule appears to be attached by its µ-chains. PMID:4829935

Trispecific antibodies for CD16A-directed NK cell engagement and dual-targeting of tumor cells.

PubMed

Gantke, Thorsten; Weichel, Michael; Herbrecht, Carmen; Reusch, Uwe; Ellwanger, Kristina; Fucek, Ivica; Eser, Markus; Müller, Thomas; Griep, Remko; Molkenthin, Vera; Zhukovsky, Eugene A; Treder, Martin

2017-09-01

Bispecific antibodies that redirect the lytic activity of cytotoxic immune effector cells, such as T- and NK cells, onto tumor cells have emerged as a highly attractive and clinically validated treatment modality for hematological malignancies. Advancement of this therapeutic concept into solid tumor indications, however, is hampered by the scarcity of targetable antigens that are surface-expressed on tumor cells but demonstrate only limited expression on healthy tissues. To overcome this limitation, the concept of dual-targeting, i.e. the simultaneous targeting of two tumor-expressed surface antigens with limited co-expression on non-malignant cells, with multispecific antibodies has been proposed to increase tumor selectivity of antibody-induced effector cell cytotoxicity. Here, a novel CD16A (FcγRIIIa)-directed trispecific, tetravalent antibody format, termed aTriFlex, is described, that is capable of redirecting NK cell cytotoxicity to two surface-expressed antigens. Using a BCMA/CD200-based in vitro model system, the potential use of aTriFlex antibodies for dual-targeting and selective induction of NK cell-mediated target cell lysis was investigated. Bivalent bispecific target cell binding was found to result in significant avidity gains and up to 17-fold increased in vitro potency. These data suggest trispecific aTriFlex antibodies may support dual-targeting strategies to redirect NK cell cytotoxicity with increased selectivity to enable targeting of solid tumor antigens. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Cell membrane antigen-antibody complex dissociation by the widely used glycine-HCL method: an unreliable procedure for studying antibody internalization.

PubMed

Tsaltas, G; Ford, C H

1993-02-01

Methods following the process of binding and internalization of antibodies to cell surface antigens have often employed low pH isoosmolar buffers in order to dissociate surface antigen-antibody complexes. One of the most widely used buffers is a 0.05 M glycine-HCL buffer pH 2.8. Since the efficacy of action of this buffer was critical to a series of internalization experiments employing monoclonal antibodies (Mabs) to carcinoembryonic antigen (CEA) expressing cancer cell lines in this laboratory, we tested its performance in a number of different assays. Our results indicate that this buffer only partially dissociates antigen-antibody bonds and therefore can introduce major inaccuracies in internalization experiments.

The effects of antibodies on cells

PubMed Central

Dumonde, D. C.; Bitensky, Lucille; Cunningham, G. J.; Chayen, J.

1965-01-01

Biochemical and histochemical methods were used to study the interaction of antibodies and complement with mouse Ehrlich ascites tumour cells. In the presence of complement, both iso- and hetero-antibodies caused cell lysis with penetration of antibodies into the damaged cells, as detected by immunofluorescence; the cells were then unable to support aerobic glycolysis though they retained their ability to consume oxygen in the presence of succinate. Under these conditions there was unmasking of phospholipid particularly at the cell surface, together with lysosomal changes resulting in diffuse staining for lysosomal acid—phosphatase. In the absence of complement, antibodies did not appear to penetrate the cells which respired normally and were not lysed. However, in these cells there was intense lysosomal activation accompanied by unmasking of cytoplasmic phospholipid; it appeared that an immune reaction confined to the cell surface was able to induce changes in the cytoplasm without acutely impairing the viability of the cell. ImagesFIGS. 1-8FIGS. 9-14 PMID:14245309

Comparative study on antibody immobilization strategies for efficient circulating tumor cell capture.

PubMed

Ates, Hatice Ceren; Ozgur, Ebru; Kulah, Haluk

2018-03-23

Methods for isolation and quantification of circulating tumor cells (CTCs) are attracting more attention every day, as the data for their unprecedented clinical utility continue to grow. However, the challenge is that CTCs are extremely rare (as low as 1 in a billion of blood cells) and a highly sensitive and specific technology is required to isolate CTCs from blood cells. Methods utilizing microfluidic systems for immunoaffinity-based CTC capture are preferred, especially when purity is the prime requirement. However, antibody immobilization strategy significantly affects the efficiency of such systems. In this study, two covalent and two bioaffinity antibody immobilization methods were assessed with respect to their CTC capture efficiency and selectivity, using an anti-epithelial cell adhesion molecule (EpCAM) as the capture antibody. Surface functionalization was realized on plain SiO 2 surfaces, as well as in microfluidic channels. Surfaces functionalized with different antibody immobilization methods are physically and chemically characterized at each step of functionalization. MCF-7 breast cancer and CCRF-CEM acute lymphoblastic leukemia cell lines were used as EpCAM positive and negative cell models, respectively, to assess CTC capture efficiency and selectivity. Comparisons reveal that bioaffinity based antibody immobilization involving streptavidin attachment with glutaraldehyde linker gave the highest cell capture efficiency. On the other hand, a covalent antibody immobilization method involving direct antibody binding by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC)-N-hydroxysuccinimide (NHS) reaction was found to be more time and cost efficient with a similar cell capture efficiency. All methods provided very high selectivity for CTCs with EpCAM expression. It was also demonstrated that antibody immobilization via EDC-NHS reaction in a microfluidic channel leads to high capture efficiency and selectivity.

CARbodies: Human Antibodies Against Cell Surface Tumor Antigens Selected From Repertoires Displayed on T Cell Chimeric Antigen Receptors

PubMed Central

Alonso-Camino, Vanesa; Sánchez-Martín, David; Compte, Marta; Nuñez-Prado, Natalia; Diaz, Rosa M; Vile, Richard; Alvarez-Vallina, Luis

2013-01-01

A human single-chain variable fragment (scFv) antibody library was expressed on the surface of human T cells after transduction with lentiviral vectors (LVs). The repertoire was fused to a first-generation T cell receptor ζ (TCRζ)-based chimeric antigen receptor (CAR). We used this library to isolate antibodies termed CARbodies that recognize antigens expressed on the tumor cell surface in a proof-of-principle system. After three rounds of activation-selection there was a clear repertoire restriction, with the emergence dominant clones. The CARbodies were purified from bacterial cultures as soluble and active proteins. Furthermore, to validate its potential application for adoptive cell therapy, human T cells were transduced with a LV encoding a second-generation costimulatory CAR (CARv2) bearing the selected CARbodies. Transduced human primary T cells expressed significant levels of the CARbodies-based CARv2 fusion protein on the cell surface, and importantly could be specifically activated, after stimulation with tumor cells. This approach is a promising tool for the generation of antibodies fully adapted to the display format (CAR) and the selection context (cell synapse), which could extend the scope of current adoptive cell therapy strategies with CAR-redirected T cells. PMID:23695536

A rapid live-cell ELISA for characterizing antibodies against cell surface antigens of Chlamydomonas reinhardtii and its use in isolating algae from natural environments with related cell wall components.

PubMed

Jiang, Wenzhi; Cossey, Sarah; Rosenberg, Julian N; Oyler, George A; Olson, Bradley J S C; Weeks, Donald P

2014-09-25

Cell walls are essential for most bacteria, archaea, fungi, algae and land plants to provide shape, structural integrity and protection from numerous biotic and abiotic environmental factors. In the case of eukaryotic algae, relatively little is known of the composition, structure or mechanisms of assembly of cell walls in individual species or between species and how these differences enable algae to inhabit a great diversity of environments. In this paper we describe the use of camelid antibody fragments (VHHs) and a streamlined ELISA assay as powerful new tools for obtaining mono-specific reagents for detecting individual algal cell wall components and for isolating algae that share a particular cell surface component. To develop new microalgal bioprospecting tools to aid in the search of environmental samples for algae that share similar cell wall and cell surface components, we have produced single-chain camelid antibodies raised against cell surface components of the single-cell alga, Chlamydomonas reinhardtii. We have cloned the variable-region domains (VHHs) from the camelid heavy-chain-only antibodies and overproduced tagged versions of these monoclonal-like antibodies in E. coli. Using these VHHs, we have developed an accurate, facile, low cost ELISA that uses live cells as a source of antigens in their native conformation and that requires less than 90 minutes to perform. This ELISA technique was demonstrated to be as accurate as standard ELISAs that employ proteins from cell lysates and that generally require >24 hours to complete. Among the cloned VHHs, VHH B11, exhibited the highest affinity (EC50 < 1 nM) for the C. reinhardtii cell surface. The live-cell ELISA procedure was employed to detect algae sharing cell surface components with C. reinhardtii in water samples from natural environments. In addition, mCherry-tagged VHH B11 was used along with fluorescence activated cell sorting (FACS) to select individual axenic isolates of presumed wild relatives of C. reinhardtii and other Chlorphyceae from the same environmental samples. Camelid antibody VHH domains provide a highly specific tool for detection of individual cell wall components of algae and for allowing the selection of algae that share a particular cell surface molecule from diverse ecosystems.

Targeting RAS-driven human cancer cells with antibodies to upregulated and essential cell-surface proteins.

PubMed

Martinko, Alexander J; Truillet, Charles; Julien, Olivier; Diaz, Juan E; Horlbeck, Max A; Whiteley, Gordon; Blonder, Josip; Weissman, Jonathan S; Bandyopadhyay, Sourav; Evans, Michael J; Wells, James A

2018-01-23

While there have been tremendous efforts to target oncogenic RAS signaling from inside the cell, little effort has focused on the cell-surface. Here, we used quantitative surface proteomics to reveal a signature of proteins that are upregulated on cells transformed with KRAS G12V , and driven by MAPK pathway signaling. We next generated a toolkit of recombinant antibodies to seven of these RAS-induced proteins. We found that five of these proteins are broadly distributed on cancer cell lines harboring RAS mutations. In parallel, a cell-surface CRISPRi screen identified integrin and Wnt signaling proteins as critical to RAS-transformed cells. We show that antibodies targeting CDCP1, a protein common to our proteomics and CRISPRi datasets, can be leveraged to deliver cytotoxic and immunotherapeutic payloads to RAS-transformed cancer cells and report for RAS signaling status in vivo. Taken together, this work presents a technological platform for attacking RAS from outside the cell. © 2018, Martinko et al.

Anti-MUC1 antibody inhibits EGF receptor signaling in cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hisatsune, Akinori, E-mail: hisatsun@kumamoto-u.ac.jp; Nakayama, Hideki; Kawasaki, Mitsuru

2011-02-18

Research highlights: {yields} We identified changes in the expression and function of EGFR by anti-MUC1 antibody. {yields} An anti-MUC1 antibody GP1.4 decreased EGFR from cell surface by internalization. {yields} GP1.4 specifically inhibited ERK signaling triggered EGF-EGFR signaling pathway. {yields} Internalization of EGFR was dependent on the presence of MUC1 on cell surface. {yields} GP1.4 significantly inhibited EGF-dependent cancer cell proliferation and migration. -- Abstract: MUC1 is a type I transmembrane glycoprotein aberrantly overexpressed in various cancer cells. High expression of MUC1 is closely associated with cancer progression and metastasis, leading to poor prognosis. We previously reported that MUC1 is internalizedmore » by the binding of the anti-MUC1 antibody, from the cell surface to the intracellular region via the macropinocytotic pathway. Since MUC1 is closely associated with ErbBs, such as EGF receptor (EGFR) in cancer cells, we examined the effect of the anti-MUC1 antibody on EGFR trafficking. Our results show that: (1) anti-MUC1 antibody GP1.4, but not another anti-MUC1 antibody C595, triggered the internalization of EGFR in pancreatic cancer cells; (2) internalization of EGFR by GP1.4 resulted in the inhibition of ERK phosphorylation by EGF stimulation, in a MUC1 dependent manner; (3) inhibition of ERK phosphorylation by GP1.4 resulted in the suppression of proliferation and migration of pancreatic cancer cells. We conclude that the internalization of EGFR by anti-MUC1 antibody GP1.4 inhibits the progression of cancer cells via the inhibition of EGFR signaling.« less

Quantitative assessment of antibody internalization with novel monoclonal antibodies against Alexa fluorophores.

PubMed

Liao-Chan, Sindy; Daine-Matsuoka, Barbara; Heald, Nathan; Wong, Tiffany; Lin, Tracey; Cai, Allen G; Lai, Michelle; D'Alessio, Joseph A; Theunissen, Jan-Willem

2015-01-01

Antibodies against cell surface antigens may be internalized through their specific interactions with these proteins and in some cases may induce or perturb antigen internalization. The anti-cancer efficacy of antibody-drug conjugates is thought to rely on their uptake by cancer cells expressing the surface antigen. Numerous techniques, including microscopy and flow cytometry, have been used to identify antibodies with desired cellular uptake rates. To enable quantitative measurements of internalization of labeled antibodies, an assay based on internalized and quenched fluorescence was developed. For this approach, we generated novel anti-Alexa Fluor monoclonal antibodies (mAbs) that effectively and specifically quench cell surface-bound Alexa Fluor 488 or Alexa Fluor 594 fluorescence. Utilizing Alexa Fluor-labeled mAbs against the EphA2 receptor tyrosine kinase, we showed that the anti-Alexa Fluor reagents could be used to monitor internalization quantitatively over time. The anti-Alexa Fluor mAbs were also validated in a proof of concept dual-label internalization assay with simultaneous exposure of cells to two different mAbs. Importantly, the unique anti-Alexa Fluor mAbs described here may also enable other single- and dual-label experiments, including label detection and signal enhancement in macromolecules, trafficking of proteins and microorganisms, and cell migration and morphology.

Kinetics of antibody-induced modulation of respiratory syncytial virus antigens in a human epithelial cell line

PubMed Central

Sarmiento, Rosa E; Tirado, Rocio G; Valverde, Laura E; Gómez-Garcia, Beatriz

2007-01-01

Background The binding of viral-specific antibodies to cell-surface antigens usually results in down modulation of the antigen through redistribution of antigens into patches that subsequently may be internalized by endocytosis or may form caps that can be expelled to the extracellular space. Here, by use of confocal-laser-scanning microscopy we investigated the kinetics of the modulation of respiratory syncytial virus (RSV) antigen by RSV-specific IgG. RSV-infected human epithelial cells (HEp-2) were incubated with anti-RSV polyclonal IgG and, at various incubation times, the RSV-cell-surface-antigen-antibody complexes (RSV Ag-Abs) and intracellular viral proteins were detected by indirect immunoflourescence. Results Interaction of anti-RSV polyclonal IgG with RSV HEp-2 infected cells induced relocalization and aggregation of viral glycoproteins in the plasma membrane formed patches that subsequently produced caps or were internalized through clathrin-mediated endocytosis participation. Moreover, the concentration of cell surface RSV Ag-Abs and intracellular viral proteins showed a time dependent cyclic variation and that anti-RSV IgG protected HEp-2 cells from viral-induced death. Conclusion The results from this study indicate that interaction between RSV cell surface proteins and specific viral antibodies alter the expression of viral antigens expressed on the cells surface and intracellular viral proteins; furthermore, interfere with viral induced destruction of the cell. PMID:17608950

[Construction of dengue virus-specific full-length fully human antibody libraries by mammalian display technology].

PubMed

Wen, Yangming; Lan, Kaijian; Wang, Junjie; Yu, Jingyi; Qu, Yarong; Zhao, Wei; Zhang, Fuchun; Tan, Wanlong; Cao, Hong; Zhou, Chen

2013-06-01

To construct dengue virus-specific full-length fully human antibody libraries using mammalian cell surface display technique. Total RNA was extracted from peripheral blood mononuclear cells (PBMCs) from convalescent patients with dengue fever. The reservoirs of the light chain and heavy chain variable regions (LCκ and VH) of the antibody genes were amplified by RT-PCR and inserted into the vector pDGB-HC-TM separately to construct the light chain and heavy chain libraries. The library DNAs were transfected into CHO cells and the expression of full-length fully human antibodies on the surface of CHO cells was analyzed by flow cytometry. Using 1.2 µg of the total RNA isolated from the PBMCs as the template, the LCκ and VH were amplified and the full-length fully human antibody mammalian display libraries were constructed. The kappa light chain gene library had a size of 1.45×10(4) and the heavy chain gene library had a size of 1.8×10(5). Sequence analysis showed that 8 out of the 10 light chain clones and 7 out of the 10 heavy chain clones randomly picked up from the constructed libraries contained correct open reading frames. FACS analysis demonstrated that all the 15 clones with correct open reading frames expressed full-length antibodies, which could be detected on CHO cell surfaces. After co-transfection of the heavy chain and light chain gene libraries into CHO cells, the expression of full-length antibodies on CHO cell surfaces could be detected by FACS analysis with an expressible diversity of the antibody library reaching 1.46×10(9) [(1.45×10(4)×80%)×(1.8×10(5)×70%)]. Using 1.2 µg of total RNA as template, the LCκ and VH full-length fully human antibody libraries against dengue virus have been successfully constructed with an expressible diversity of 10(9).

Monoclonal Antibody and an Antibody-Toxin Conjugate to a Cell Surface Proteoglycan of Melanoma Cells Suppress in vivo Tumor Growth

NASA Astrophysics Data System (ADS)

Bumol, T. F.; Wang, Q. C.; Reisfeld, R. A.; Kaplan, N. O.

1983-01-01

A monoclonal antibody directed against a cell surface chondroitin sulfate proteoglycan of human melanoma cells, 9.2.27, and its diphtheria toxin A chain (DTA) conjugate were investigated for their effects on in vitro protein synthesis and in vivo tumor growth of human melanoma cells. The 9.2.27 IgG and its DTA conjugate display similar serological activities against melanoma target cells but only the conjugate can induce consistent in vitro inhibition of protein synthesis and toxicity in M21 melanoma cells. However, both 9.2.27 IgG and its DTA conjugate effect significant suppression of M21 tumor growth in vivo in an immunotherapy model of a rapidly growing tumor in athymic nu/nu mice, suggesting that other host mechanisms may mediate monoclonal antibody-induced tumor suppression.

Obligate multivalent recognition of cell surface tomoregulin following selection from a multivalent phage antibody library.

PubMed

Heitner, Tara; Satozawa, Noboru; McLean, Kirk; Vogel, David; Cobb, Ronald R; Liu, Bing; Mahmoudi, Mithra; Finster, Silke; Larsen, Brent; Zhu, Ying; Zhou, Hongxing; Müller-Tiemann, Beate; Monteclaro, Felipe; Zhao, Xiao-Yan; Light, David R

2006-12-01

A therapeutic antibody candidate (AT-19) isolated using multivalent phage display binds native tomoregulin (TR) as a mul-timer not as a monomer. This report raises the importance of screening and selecting phage antibodies on native antigen and reemphasizes the possibility that potentially valuable antibodies are discarded when a monomeric phage display system is used for screening. A detailed live cell panning selection and screening method to isolate multivalently active antibodies is described. AT-19 is a fully human antibody recognizing the cell surface protein TR, a proposed prostate cancer target for therapeutic antibody internalization. AT-19 was isolated from a multivalent single-chain variable fragment (scFv) antibody library rescued with hyperphage. The required multivalency for isolation of AT-19 is supported by fluorescence activated cell sorting data demonstrating binding of the multivalent AT-19 phage particles at high phage concentrations and failure of monovalent particles to bind. Pure monomeric scFv AT-19 does not bind native receptor on cells, whereas dimeric scFv or immunoglobulin G binds with nanomolar affinity. The isolation of AT-19 antibody with obligate bivalent binding activity to native TR is attributed to the use of a multivalent display of scFv on phage and the method for selecting and screening by alternate use of 2 recombinant cell lines.

Method of rapid production of hybridomas expressing monoclonal antibodies on the cell surface

DOEpatents

Meagher, Richard B.; Laterza, Vince

2006-12-12

The present invention relates to genetically altered hybridomas, myelomas and B cells. The invention also relates to utilizing genetically altered hybridomas, myelomas and B cells in methods of making monoclonal antibodies. The present invention also provides populations of hybridomas and B cells that can be utilized to make a monoclonal antibody of interest.

A mathematical model of antibody-dependent cellular cytotoxicity (ADCC).

PubMed

Hoffman, F; Gavaghan, D; Osborne, J; Barrett, I P; You, T; Ghadially, H; Sainson, R; Wilkinson, R W; Byrne, H M

2018-01-07

Immunotherapies exploit the immune system to target and kill cancer cells, while sparing healthy tissue. Antibody therapies, an important class of immunotherapies, involve the binding to specific antigens on the surface of the tumour cells of antibodies that activate natural killer (NK) cells to kill the tumour cells. Preclinical assessment of molecules that may cause antibody-dependent cellular cytotoxicity (ADCC) involves co-culturing cancer cells, NK cells and antibody in vitro for several hours and measuring subsequent levels of tumour cell lysis. Here we develop a mathematical model of such an in vitro ADCC assay, formulated as a system of time-dependent ordinary differential equations and in which NK cells kill cancer cells at a rate which depends on the amount of antibody bound to each cancer cell. Numerical simulations generated using experimentally-based parameter estimates reveal that the system evolves on two timescales: a fast timescale on which antibodies bind to receptors on the surface of the tumour cells, and NK cells form complexes with the cancer cells, and a longer time-scale on which the NK cells kill the cancer cells. We construct approximate model solutions on each timescale, and show that they are in good agreement with numerical simulations of the full system. Our results show how the processes involved in ADCC change as the initial concentration of antibody and NK-cancer cell ratio are varied. We use these results to explain what information about the tumour cell kill rate can be extracted from the cytotoxicity assays. Copyright © 2017 Elsevier Ltd. All rights reserved.

Escherichia coli surface display of single-chain antibody VRC01 against HIV-1 infection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lin-Xu; School of Biological Sciences, University of Nebraska—Lincoln, Lincoln, NE 68583; Mellon, Michael

Human immunodeficiency virus type 1 (HIV-1) transmission and infection occur mainly via the mucosal surfaces. The commensal bacteria residing in these surfaces can potentially be employed as a vehicle for delivering inhibitors to prevent HIV-1 infection. In this study, we have employed a bacteria-based strategy to display a broadly neutralizing antibody VRC01, which could potentially be used to prevent HIV-1 infection. The VRC01 antibody mimics CD4-binding to gp120 and has broadly neutralization activities against HIV-1. We have designed a construct that can express the fusion peptide of the scFv-VRC01 antibody together with the autotransporter β-barrel domain of IgAP gene frommore » Neisseria gonorrhoeae, which enabled surface display of the antibody molecule. Our results indicate that the scFv-VRC01 antibody molecule was displayed on the surface of the bacteria as demonstrated by flow cytometry and immunofluorescence microscopy. The engineered bacteria can capture HIV-1 particles via surface-binding and inhibit HIV-1 infection in cell culture. - Highlights: • Designed single-chain VRC01 antibody was demonstrated to bind HIV-1 envelope gp120. • Single-chain VRC01 antibody was successfully displayed on the surface of E. coli. • Engineered bacteria can absorb HIV-1 particles and prevent HIV-1 infection in cell culture.« less

Anti-idiotypic antibodies that protect cells against the action of diphtheria toxin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rolf, J.M.; Gaudin, H.M.; Tirrell, S.M.

1989-03-01

An anti-idiotypic serum prepared against the combining site (idiotype) of specific anti-diphtheria toxoid antibodies was characterized with respect to its interaction with highly diphtheria toxin-sensitive Vero cells. Although the anti-idiotypic serum protected Vero cells against the cytotoxic action of diphtheria toxin, it did not prevent the binding of /sup 125/I-labeled diphtheria toxin to the cells but did inhibit the internalization and degradation of /sup 125/I-labeled toxin. This anti-idiotypic serum immunoprecipitated a cell-surface protein from radiolabeled Vero cells with an apparent Mr of approximately 15,000. These results are consistent with the hypothesis that the anti-idiotypic serum contains antibodies that carry anmore » internal image of an internalization site on the toxin and that a cell-surface protein involved in toxin internalization possesses a complementary site recognized by both the toxin and the anti-idiotypic antibodies.« less

Three-dimensional imaging of nucleolin trafficking in normal cells, transfectants, and heterokaryons

NASA Astrophysics Data System (ADS)

Ballou, Byron T.; Fisher, Gregory W.; Deng, Jau-Shyong; Hakala, Thomas R.; Srivastava, Meera; Farkas, Daniel L.

1996-04-01

The study of intracellular trafficking using labeled molecules has been aided by the development of the cyanine fluorochromes, which are easily coupled, very soluble, resist photobleaching, and fluoresce at far-red wavelengths where background fluorescence is minimal. We have used Cy3-, Cy5-, and Cy5.5-labeled antibodies, antigen-binding fragments, and specifically binding single-stranded oligonucleotides to follow expression and trafficking of nucleolin, the most abundant protein of the nucleolus. Nucleolin shuttles between the nucleolus and the cytoplasm, and is also expressed on the cell surface, allowing us to test our techniques at all three cellular sites. Differentially cyanine-labeled non-specific antibodies were used to control for non-specific binding. Similarly, the differentially labeled non-binding strand of the cloned oligonucleotide served as a control. The multimode microscope allowed us to follow both rapid and slow redistributions of labeled ligands in the same study. We also performed 3-D reconstructions of nucleolin distribution in cells using rapid acquisition and deconvolution. Microinjection of labeled ligands was used to follow intracellular distribution, while incubation of whole cells with antibody and antigen-binding fragments was used to study uptake. To unambiguously define trafficking, and eliminate the possibility of interference by cross-reactive proteins, we transfected mouse renal cell carcinoma cells that express cell surface nucleolin with human nucleolin. We used microinjection and cell surface staining with Cy3- or Cy5- labeled monoclonal antibody D3 (specific for human nucleolin) to assess the cellular distribution of the human protein. Several clones expressed human nucleolin on their surfaces and showed high levels of transport of the human protein into the mouse nucleus and nucleolus. This distribution roughly parallels that of mouse nucleolin as determined by labeled polyclonal antibody. We have used these engineered transfectants to determine whether the cell surface-expressed xenogeneic nucleolin can serve as a target for antibodies in vivo.

A panel of recombinant monoclonal antibodies against zebrafish neural receptors and secreted proteins suitable for wholemount immunostaining.

PubMed

Staudt, Nicole; Müller-Sienerth, Nicole; Fane-Dremucheva, Alla; Yusaf, Shahnaz P; Millrine, David; Wright, Gavin J

2015-01-02

Cell surface receptors and secreted proteins play important roles in neural recognition processes, but because their site of action can be a long distance from neuron cell bodies, antibodies that label these proteins are valuable to understand their function. The zebrafish embryo is a popular vertebrate model for neurobiology, but suffers from a paucity of validated antibody reagents. Here, we use the entire ectodomain of neural zebrafish cell surface or secreted proteins expressed in mammalian cells to select monoclonal antibodies to ten different antigens. The antibodies were characterised by Western blotting and the sensitivity of their epitopes to formalin fixation was determined. The rearranged antigen binding regions of the antibodies were amplified and cloned which enabled expression in a recombinant form from a single plasmid. All ten antibodies gave specific staining patterns within formalin-treated embryonic zebrafish brains, demonstrating that this generalised approach is particularly efficient to elicit antibodies that stain native antigen in fixed wholemount tissue. Finally, we show that additional tags can be easily added to the recombinant antibodies for convenient multiplex staining. The antibodies and the approaches described here will help to address the lack of well-defined antibody reagents in zebrafish research. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Structure of the Plexin Ectodomain Bound by Semaphorin-Mimicking Antibodies

PubMed Central

Omiya, Ryusuke; Matoba, Kyoko; Baba, Takeshi; Suzuki, Sachiyo; Segawa, Hiroaki; Kumanogoh, Atsushi; Iwasaki, Kenji; Hattori, Kunihiro; Takagi, Junichi

2016-01-01

Semaphorin family proteins act on cells to mediate both repulsive and attractive guidance via binding to plexin family receptors, thereby playing fundamental roles in the morphogenesis and homeostasis of various tissues. Although semaphorin-plexin signaling is implicated in various diseases and is thus a target of intensive research, our mechanistic understanding of how semaphorins activate plexins on the cell surface is limited. Here, we describe unique anti-plexin-A1 antibodies that can induce a collapsed morphology in mouse dendritic cells as efficiently as the semaphorin 3A (Sema3A) ligand. Precise epitope analysis indicates that these “semaphorin-mimicking” antibodies dimerize cell-surface plexin-A1 by binding to the N-terminal sema domain of the plexin at sites away from the interface used by the Sema3A ligand. Structural analysis of plexin-A1 fragments using negative stain electron microscopy further revealed that this agonistic capacity is closely linked to the location and orientation of antibody binding. In addition, the full-length plexin-A1 ectodomain exhibited a highly curved “C” shape, reinforcing the very unusual dimeric receptor conformation of this protein at the cell surface when engaged with Sema3A or agonistic antibodies. PMID:27258772

Presence of antibodies against a cell-surface protein, cross-reactive with DNA, in systemic lupus erythrematosus: a marker of the disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacob, L.; Lety, M.A.; Choquette, D.

1987-05-01

Antibodies against a cell-surface protein, cross-reactive with double-stranded DNA, were detected in the serum of 25 patients with active human systemic lupus erythematosus (SLE), defined on the basis of the revised American Rheumatism Association classification. Among these sera, two did not display anti-DNA antibodies, as shown by Farr assay, solid-phase radioimmunoassay, and Crithidia luciliae test. Five other SLE patients were consecutively studied in active and remission states. Antibodies against the protein were detected in the serum of the 5 SLE patients when they were in active phase but not in the serum of the same patients in inactive phase ofmore » the disease. The anti-protein antibodies were not found in the serum of 10 inactive SLE patients or in the sera of 10 normal human controls, 10 patients with rheumatoid arthritis, 5 patients with scleroderma, and 4 patients with primary sicca syndrome. Taken together, these results strongly suggest that antibodies against this cell-surface protein could provide a better diagnosis marker and activity index than anti-DNA antibodies in SLE.« less

Selection of phage-displayed accessible recombinant targeted antibodies (SPARTA): methodology and applications.

PubMed

D'Angelo, Sara; Staquicini, Fernanda I; Ferrara, Fortunato; Staquicini, Daniela I; Sharma, Geetanjali; Tarleton, Christy A; Nguyen, Huynh; Naranjo, Leslie A; Sidman, Richard L; Arap, Wadih; Bradbury, Andrew Rm; Pasqualini, Renata

2018-05-03

We developed a potentially novel and robust antibody discovery methodology, termed selection of phage-displayed accessible recombinant targeted antibodies (SPARTA). This combines an in vitro screening step of a naive human antibody library against known tumor targets, with in vivo selections based on tumor-homing capabilities of a preenriched antibody pool. This unique approach overcomes several rate-limiting challenges to generate human antibodies amenable to rapid translation into medical applications. As a proof of concept, we evaluated SPARTA on 2 well-established tumor cell surface targets, EphA5 and GRP78. We evaluated antibodies that showed tumor-targeting selectivity as a representative panel of antibody-drug conjugates (ADCs) and were highly efficacious. Our results validate a discovery platform to identify and validate monoclonal antibodies with favorable tumor-targeting attributes. This approach may also extend to other diseases with known cell surface targets and affected tissues easily isolated for in vivo selection.

Antibody-immobilized column for quick cell separation based on cell rolling.

PubMed

Mahara, Atsushi; Yamaoka, Tetsuji

2010-01-01

Cell separation using methodological standards that ensure high purity is a very important step in cell transplantation for regenerative medicine and for stem cell research. A separation protocol using magnetic beads has been widely used for cell separation to isolate negative and positive cells. However, not only the surface marker pattern, e.g., negative or positive, but also the density of a cell depends on its developmental stage and differentiation ability. Rapid and label-free separation procedures based on surface marker density are the focus of our interest. In this study, we have successfully developed an antiCD34 antibody-immobilized cell-rolling column, that can separate cells depending on the CD34 density of the cell surfaces. Various conditions for the cell-rolling column were optimized including graft copolymerization, and adjustment of the column tilt angle, and medium flow rate. Using CD34-positive and -negative cell lines, the cell separation potential of the column was established. We observed a difference in the rolling velocities between CD34-positive and CD34-negative cells on antibody-immobilized microfluidic device. Cell separation was achieved by tilting the surface 20 degrees and the increasing medium flow. Surface marker characteristics of the isolated cells in each fraction were analyzed using a cell-sorting system, and it was found that populations containing high density of CD34 were eluted in the delayed fractions. These results demonstrate that cells with a given surface marker density can be continuously separated using the cell rolling column.

Antibody enhancement of free-flow electrophoresis

NASA Technical Reports Server (NTRS)

Cohly, H. H. P.; Morrison, Dennis R.; Atassi, M. Zouhair

1988-01-01

Specific T cell clones and antibodies (ABs) were developed to study the efficiency of purifying closely associated T cells using Continuous Flow Electrophoresis System. Enhanced separation is accomplished by tagging cells first with ABs directed against the antigenic determinants on the cell surface and then with ABs against the Fc portion of the first AB. This second AB protrudes sufficiently beyond the cell membrane and glycocalyx to become the major overall cell surface potential determinant and thus causes a reduction of electrophoretic mobility. This project was divided into three phases. Phase one included development of specific T cell clones and separation of these specific clones. Phase two extends these principles to the separation of T cells from spleen cells and immunized lymph node cells. Phase three applies this double antibody technique to the separation of T cytotoxic cells from bone marrow.

Nanotube antibody biosensor arrays for the detection of circulating breast cancer cells

NASA Astrophysics Data System (ADS)

Shao, Ning; Wickstrom, Eric; Panchapakesan, Balaji

2008-11-01

Recent reports have shown that nanoscale electronic devices can be used to detect a change in electrical properties when receptor proteins bind to their corresponding antibodies functionalized on the surface of the device, in extracts from as few as ten lysed tumor cells. We hypothesized that nanotube-antibody devices could sensitively and specifically detect entire live cancer cells. We report for the first time a single nanotube field effect transistor array, functionalized with IGF1R-specific and Her2-specific antibodies, which exhibits highly sensitive and selective sensing of live, intact MCF7 and BT474 human breast cancer cells in human blood. Those two cell lines both overexpress IGF1R and Her2, at different levels. Single or small bundle of nanotube devices that were functionalized with IGF1R-specific or Her2-specific antibodies showed 60% decreases in conductivity upon interaction with BT474 or MCF7 breast cancer cells in two µl drops of blood. Control experiments with non-specific antibodies or with MCF10A control breast cells produced a less than 5% decrease in electrical conductivity, illustrating the high sensitivity for whole cell binding by these single nanotube-antibody devices. We postulate that the free energy change due to multiple simultaneous cell-antibody binding events exerted stress along the nanotube surface, decreasing its electrical conductivity due to an increase in band gap. Because the free energy change upon cell-antibody binding, the stress exerted on the nanotube, and the change in conductivity are specific to a specific antigen-antibody interaction; these properties might be used as a fingerprint for the molecular sensing of circulating cancer cells. From optical microscopy observations during sensing, it appears that the binding of a single cell to a single nanotube field effect transistor produced the change in electrical conductivity. Thus we report a nanoscale oncometer with single cell sensitivity with a diameter 1000 times smaller than a cancer cell that functions in a drop of fresh blood.

Genetic modification of mesenchymal stem cells to express a single-chain antibody against EGFRvIII on the cell surface.

PubMed

Balyasnikova, Irina V; Franco-Gou, Rosa; Mathis, J Michael; Lesniak, Maciej S

2010-06-01

Human adult mesenchymal stem cells (hMSCs) are under active investigation as cellular carriers for gene therapy. hMSCs possess natural tropism toward tumours; however, the targeting of hMSCs to specific cell populations within tumours is unexplored. In the case of glioblastoma multiforme (GBM), at least half of the tumours express EGFRvIII on the cell surface, an ideal target for antibody-mediated gene/drug delivery. In this study, we investigated the feasibility of genetically modifying hMSCs to express a single-chain antibody (scFv) to EGFRvIII on their surfaces. Nucleofection was used to transfect hMSCs with cDNA encoding scFv EGFRvIII fused with PDGFR or human B7-1 transmembrane domains. The expression of scFv EGFRvIII on the cell surface was assessed by FACS. A stable population of scFv EGFRvIII-expressing hMSCs was selected, based on antibiotic resistance, and enriched using FACS. We found that nucleofection allows the efficient expression of scFv EGFRvIII on the cell surface of hMSCs. hMSCs transfected with the construct encoding scFv EGFRvIII as a fusion with PDGFRtm showed scFv EGFRvIII expression in up to 86% of cells. Most importantly, human MSCs expressing scFv against EGFRvIII demonstrated enhanced binding to U87-EGFRvIII cells in vitro and significantly increased retention in human U87-EGFRvIII-expressing tumours in vivo. In summary, we provide the first conclusive evidence of genetic modification of hMSCs with a single-chain antibody against an antigen expressed on the surface of tumour cells, thereby opening up a new venue for enhanced delivery of gene therapy applications in the context of malignant brain cancer. Copyright 2009 John Wiley & Sons, Ltd.

The sebaceous gland antigen defined by the OM-1 monoclonal antibody is expressed at high density on the surface of ovarian carcinoma cells.

PubMed

de Kretser, T A; Thorne, H J; Jacobs, D J; Jose, D G

1985-09-01

A monoclonal antibody, designated OM-1, was raised against ovarian serous papillary cystadenocarcinoma (stage IV) cells. This antibody was found to react strongly with primary and metastatic ovarian serous cystadenocarcinomas and endometrioid carcinomas but the antigen detected was either absent or at very low levels in ovarian mucinous adenocarcinomas, clear cell carcinomas, benign serous and mucinous cystadenomas and Brenner tumours. The OM-1 antibody gave no detectable reaction with 93 other human tumours, including examples of breast and colon adenocarcinomas. In normal tissues the OM-1 antibody reacted with normal sebaceous gland cells, lung type II pneumocytes and placental syncytial trophoblasts. In the normal ovary OM-1 reactivity was confined to extremely weak staining of the surface epithelium. No reaction with any other ovarian cell type could be detected. No evidence of reaction with other normal cell populations present in 24 adult and seven foetal tissues was found. The antigen detected is compared with other ovarian tumour-associated antigens. The OM-1 antibody is likely to prove of value in the detection and diagnosis of ovarian carcinoma.

Biomarker-Based Metabolic Labeling for Redirected and Enhanced Immune Response.

PubMed

Li, Shanshan; Yu, Bingchen; Wang, Jiajia; Zheng, Yueqin; Zhang, Huajie; Walker, Margaret J; Yuan, Zhengnan; Zhu, He; Zhang, Jun; Wang, Peng George; Wang, Binghe

2018-06-01

Installation of an antibody-recruiting moiety on the surface of disease-relevant cells can lead to the selective destruction of targets by the immune system. Such an approach can be an alternative strategy to traditional chemotherapeutics in cancer therapy and possibly other diseases. Herein we describe the development of a new strategy to selectively label targets with an antibody-recruiting moiety through its covalent and stable installation, complementing existing methods of employing reversible binding. This is achieved through selective delivery of 1,3,4- O-acetyl- N-azidoacetylmannosamine (Ac 3 ManNAz) to folate receptor-overexpressing cells using an Ac 3 ManNAz-folate conjugate via a cleavable linker. As such, Ac 3 ManNAz is converted to cell surface glycan bearing an azido group, which serves as an anchor to introduce l-rhamnose (Rha), a hapten, via a click reaction with aza-dibenzocyclooctyne (DBCO)-Rha. We tested this method in several cell lines including KB, HEK-293, and MCF7 and were able to demonstrate the following: 1) Rha can be selectively installed to the folate receptor overexpressing cell surface and 2) the Rha installed on the target surface can recruit anti-rhamnose (anti-Rha) antibodies, leading to the destruction of target cells via complement-dependent cytotoxicity (CDC) and antibody-dependent cellular phagocytosis (ADCP).

Ephrin-B2 prevents N-methyl-D-aspartate receptor antibody effects on memory and neuroplasticity.

PubMed

Planagumà, Jesús; Haselmann, Holger; Mannara, Francesco; Petit-Pedrol, Mar; Grünewald, Benedikt; Aguilar, Esther; Röpke, Luise; Martín-García, Elena; Titulaer, Maarten J; Jercog, Pablo; Graus, Francesc; Maldonado, Rafael; Geis, Christian; Dalmau, Josep

2016-09-01

To demonstrate that ephrin-B2 (the ligand of EphB2 receptor) antagonizes the pathogenic effects of patients' N-methyl-D-aspartate receptor (NMDAR) antibodies on memory and synaptic plasticity. One hundred twenty-two C57BL/6J mice infused with cerebrospinal fluid (CSF) from patients with anti-NMDAR encephalitis or controls, with or without ephrin-B2, were investigated. CSF was infused through ventricular catheters connected to subcutaneous osmotic pumps over 14 days. Memory, behavioral tasks, locomotor activity, presence of human antibodies specifically bound to hippocampal NMDAR, and antibody effects on the density of cell-surface and synaptic NMDAR and EphB2 were examined at different time points using reported techniques. Short- and long-term synaptic plasticity were determined in acute brain sections; the Schaffer collateral pathway was stimulated and the field excitatory postsynaptic potentials were recorded in the CA1 region of the hippocampus. Mice infused with patients' CSF, but not control CSF, developed progressive memory deficit and depressive-like behavior along with deposits of NMDAR antibodies in the hippocampus. These findings were associated with a decrease of the density of cell-surface and synaptic NMDAR and EphB2, and marked impairment of long-term synaptic plasticity without altering short-term plasticity. Administration of ephrin-B2 prevented the pathogenic effects of the antibodies in all the investigated paradigms assessing memory, depressive-like behavior, density of cell-surface and synaptic NMDAR and EphB2, and long-term synaptic plasticity. Administration of ephrin-B2 prevents the pathogenic effects of anti-NMDAR encephalitis antibodies on memory and behavior, levels of cell-surface NMDAR, and synaptic plasticity. These findings reveal a strategy beyond immunotherapy to antagonize patients' antibody effects. Ann Neurol 2016;80:388-400. © 2016 American Neurological Association.

Generation of Monoclonal Antibodies against Immunoglobulin Proteins of the Domestic Ferret (Mustela putorius furo)

PubMed Central

2017-01-01

The domestic ferret (Mustela putorius furo) serves as an animal model for the study of several viruses that cause human disease, most notably influenza. Despite the importance of this animal model, characterization of the immune response by flow cytometry (FCM) is severely hampered due to the limited number of commercially available reagents. To begin to address this unmet need and to facilitate more in-depth study of ferret B cells including the identification of antibody-secreting cells, eight unique murine monoclonal antibodies (mAb) with specificity for ferret immunoglobulin (Ig) were generated using conventional B cell hybridoma technology. These mAb were screened for reactivity against ferret peripheral blood mononuclear cells by FCM and demonstrate specificity for CD79β+ B cells. Several of these mAb are specific for the light chain of surface B cell receptor (BCR) and enable segregation of kappa and lambda B cells. Additionally, a mAb that yielded surface staining of nearly all surface BCR positive cells (i.e., pan ferret Ig) was generated. Collectively, these MαF-Ig mAb offer advancement compared to the existing portfolio of polyclonal anti-ferret Ig detection reagents and should be applicable to a wide array of immunologic assays including the identification of antibody-secreting cells by FCM. PMID:28286781

Single-Cell Droplet Microfluidic Screening for Antibodies Specifically Binding to Target Cells.

PubMed

Shembekar, Nachiket; Hu, Hongxing; Eustace, David; Merten, Christoph A

2018-02-20

Monoclonal antibodies are a main player in modern drug discovery. Many antibody screening formats exist, each with specific advantages and limitations. Nonetheless, it remains challenging to screen antibodies for the binding of cell-surface receptors (the most important class of all drug targets) or for the binding to target cells rather than purified proteins. Here, we present a high-throughput droplet microfluidics approach employing dual-color normalized fluorescence readout to detect antibody binding. This enables us to obtain quantitative data on target cell recognition, using as little as 33 fg of IgG per assay. Starting with an excess of hybridoma cells releasing unspecific antibodies, individual clones secreting specific binders (of target cells co-encapsulated into droplets) could be enriched 220-fold after sorting 80,000 clones in a single experiment. This opens the way for therapeutic antibody discovery, especially since the single-cell approach is in principle also applicable to primary human plasma cells. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Monoclonal antibodies directed against surface molecules of multicell spheroids

NASA Technical Reports Server (NTRS)

Martinez, Andrew O.

1993-01-01

The objective of this project is to generate a library of monoclonal antibodies (MAb's) to surface molecules involved in the cell-cell interactions of mammalian cells grown as multicell spheroids (MCS). MCS are highly organized 3-dimensional multicellular structures which exhibit many characteristics in vivo tissues not found in conventional monolayer or suspension culture. They also provide a functional assay for surface adhesion molecules. In brief, MCS combine the relevance of organized tissues with the accuracy of in vitro methodology. Further, one can manipulate these MCS experimentally to discern important information about their biology.

Direct measurement of IgM-Antigen interaction energy on individual red blood cells.

PubMed

Yeow, Natasha; Tabor, Rico F; Garnier, Gil

2017-07-01

Most blood grouping tests rely on the principle of red blood cells (RBCs) agglutination. Agglutination is triggered by the binding of specific blood grouping antibodies to the corresponding RBC surface antigen on multiple cells. The interaction energies between blood grouping antibodies and antigens have been poorly defined in immunohaematology. Here for the first time, we functionalized atomic force microscope (AFM) cantilevers with the IgM form of blood grouping antibodies to probe populations of individual RBCs of different groups under physiological conditions. The force-mapping mode of AFM allowed us to measure specific antibody - antigen interactions, and simultaneously localize and quantify antigen sites on the scanned cell surface. This study provides a new insight of the interactions between IgM antibodies and its corresponding antigen. The technique and information can be translated to develop better blood typing diagnostics and optimize target-specific drug delivery for medical applications. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Anti-CD22/CD20 Bispecific antibody with enhanced trogocytosis for treatment of Lupus.

PubMed

Rossi, Edmund A; Chang, Chien-Hsing; Goldenberg, David M

2014-01-01

The humanized anti-CD22 antibody, epratuzumab, has demonstrated therapeutic activity in clinical trials of lymphoma, leukemia and autoimmune diseases, treating currently over 1500 cases of non-Hodgkin lymphoma, acute lymphoblastic leukemias, Waldenström's macroglobulinemia, Sjögren's syndrome, and systemic lupus erythematosus. Because epratuzumab reduces on average only 35% of circulating B cells in patients, and has minimal antibody-dependent cellular cytotoxicity and negligible complement-dependent cytotoxicity when evaluated in vitro, its therapeutic activity may not result completely from B-cell depletion. We reported recently that epratuzumab mediates Fc/FcR-dependent membrane transfer from B cells to effector cells via trogocytosis, resulting in a substantial reduction of multiple BCR modulators, including CD22, CD19, CD21, and CD79b, as well as key cell adhesion molecules, including CD44, CD62L, and β7 integrin, on the surface of B cells in peripheral blood mononuclear cells obtained from normal donors or SLE patients. Rituximab has clinical activity in lupus, but failed to achieve primary endpoints in a Phase III trial. This is the first study of trogocytosis mediated by bispecific antibodies targeting neighboring cell-surface proteins, CD22, CD20, and CD19, as demonstrated by flow cytometry and immunofluorescence microscopy. We show that, compared to epratuzumab, a bispecific hexavalent antibody comprising epratuzumab and veltuzumab (humanized anti-CD20 mAb) exhibits enhanced trogocytosis resulting in major reductions in B-cell surface levels of CD19, CD20, CD21, CD22, CD79b, CD44, CD62L and β7-integrin, and with considerably less immunocompromising B-cell depletion that would result with anti-CD20 mAbs such as veltuzumab or rituximab, given either alone or in combination with epratuzumab. A CD22/CD19 bispecific hexavalent antibody, which exhibited enhanced trogocytosis of some antigens and minimal B-cell depletion, may also be therapeutically useful. The bispecific antibody is a candidate for improved treatment of lupus and other autoimmune diseases, offering advantages over administration of the two parental antibodies in combination.

CD47-blocking immunotherapies stimulate macrophage-mediated destruction of small-cell lung cancer

PubMed Central

Weiskopf, Kipp; Jahchan, Nadine S.; Schnorr, Peter J.; Ring, Aaron M.; Maute, Roy L.; Volkmer, Anne K.; Volkmer, Jens-Peter; Liu, Jie; Lim, Jing Shan; Yang, Dian; Seitz, Garrett; Nguyen, Thuyen; Wu, Di; Guerston, Heather; Trapani, Francesca; George, Julie; Poirier, John T.; Gardner, Eric E.; Miles, Linde A.; de Stanchina, Elisa; Lofgren, Shane M.; Vogel, Hannes; Winslow, Monte M.; Dive, Caroline; Thomas, Roman K.; Rudin, Charles M.; van de Rijn, Matt; Majeti, Ravindra; Garcia, K. Christopher; Weissman, Irving L.

2016-01-01

Small-cell lung cancer (SCLC) is a highly aggressive subtype of lung cancer with limited treatment options. CD47 is a cell-surface molecule that promotes immune evasion by engaging signal-regulatory protein alpha (SIRPα), which serves as an inhibitory receptor on macrophages. Here, we found that CD47 is highly expressed on the surface of human SCLC cells; therefore, we investigated CD47-blocking immunotherapies as a potential approach for SCLC treatment. Disruption of the interaction of CD47 with SIRPα using anti-CD47 antibodies induced macrophage-mediated phagocytosis of human SCLC patient cells in culture. In a murine model, administration of CD47-blocking antibodies or targeted inactivation of the Cd47 gene markedly inhibited SCLC tumor growth. Furthermore, using comprehensive antibody arrays, we identified several possible therapeutic targets on the surface of SCLC cells. Antibodies to these targets, including CD56/neural cell adhesion molecule (NCAM), promoted phagocytosis in human SCLC cell lines that was enhanced when combined with CD47-blocking therapies. In light of recent clinical trials for CD47-blocking therapies in cancer treatment, these findings identify disruption of the CD47/SIRPα axis as a potential immunotherapeutic strategy for SCLC. This approach could enable personalized immunotherapeutic regimens in patients with SCLC and other cancers. PMID:27294525

Function-blocking antibodies to human vascular adhesion protein-1: a potential anti-inflammatory therapy.

PubMed

Kirton, Christopher M; Laukkanen, Marja-Leena; Nieminen, Antti; Merinen, Marika; Stolen, Craig M; Armour, Kathryn; Smith, David J; Salmi, Marko; Jalkanen, Sirpa; Clark, Michael R

2005-11-01

Human vascular adhesion protein-1 (VAP-1) is a homodimeric 170-kDa sialoglycoprotein that is expressed on the surface of endothelial cells and functions as a semicarbazide-sensitive amine oxidase and as an adhesion molecule. Blockade of VAP-1 has been shown to reduce leukocyte adhesion and transmigration in in vivo and in vitro models, suggesting that VAP-1 is a potential target for anti-inflammatory therapy. In this study we have constructed mouse-human chimeric antibodies by genetic engineering in order to circumvent the potential problems involved in using murine antibodies in man. Our chimeric anti-VAP-1 antibodies, which were designed to lack Fc-dependent effector functions, bound specifically to cell surface-expressed recombinant human VAP-1 and recognized VAP-1 in different cell types in tonsil. Furthermore, the chimeric antibodies prevented leukocyte adhesion and transmigration in vitro and in vivo. Hence, these chimeric antibodies have the potential to be used as a new anti-inflammatory therapy.

Production of a Recombinant Antibody Specific for i Blood Group Antigen, a Mesenchymal Stem Cell Marker

PubMed Central

Suila, Heli; Tiitinen, Sari; Natunen, Suvi; Laukkanen, Marja-Leena; Kotovuori, Annika; Reinman, Mirka; Satomaa, Tero; Alfthan, Kaija; Laitinen, Saara; Takkinen, Kristiina; Räbinä, Jarkko; Valmu, Leena

2013-01-01

Abstract Multipotent mesenchymal stem/stromal cells (MSCs) offer great promise for future regenerative and anti-inflammatory therapies. Panels of functional and phenotypical markers are currently used in characterization of different therapeutic stem cell populations from various sources. The i antigen (linear poly-N-acetyllactosamine) from the Ii blood group system has been suggested as a marker for MSCs derived from umbilical cord blood (UCB). However, there are currently no commercially available antibodies recognizing the i antigen. In the present study, we describe the use of antibody phage display technology to produce recombinant antibodies recognizing a structure from the surface of mesenchymal stem cells. We constructed IgM phage display libraries from the lymphocytes of a donor with an elevated serum anti-i titer. Antibody phage display technology is not dependent on immunization and thus allows the generation of antibodies against poorly immunogenic molecules, such as carbohydrates. Agglutination assays utilizing i antigen–positive red blood cells (RBCs) from UCB revealed six promising single-chain variable fragment (scFv) antibodies, three of which recognized epitopes from the surface of UCB-MSCs in flow cytometric assays. The amino acid sequence of the VH gene segment of B12.2 scFv was highly similar to the VH4.21 gene segment required to encode anti-i specificities. Further characterization of binding properties revealed that the binding of B12.2 hyperphage was inhibited by soluble linear lactosamine oligosaccharide. Based on these findings, we suggest that the B12.2 scFv we have generated is a prominent anti-i antibody that recognizes i antigen on the surface of both UCB-MSCs and RBCs. This binder can thus be utilized in UCB-MSC detection and isolation as well as in blood group serology. PMID:24083089

Antibody-Directed Cytotoxic Agents: Use of Monoclonal Antibody to Direct the Action of Toxin A Chains to Colorectal Carcinoma Cells

NASA Astrophysics Data System (ADS)

Gilliland, D. Gary; Steplewski, Zenon; Collier, R. John; Mitchell, Kenneth F.; Chang, Tong H.; Koprowski, Hilary

1980-08-01

We have constructed cell-specific cytotoxic agents by covalently coupling the A chain from diphtheria toxin or ricin toxin to monoclonal antibody directed against a colorectal carcinoma tumor-associated antigen. Antibody 1083-17-1A was modified by attachment of 3-(2-pyridyldithio)propionyl or cystaminyl groups and then treated with reduced A chain to give disulfide-linked conjugates that retained the original binding specificity of the antibody moiety. The conjugates showed cytotoxic activity for colorectal carcinoma cells in culture, but were not toxic in the same concentration range for a variety of cell lines that lacked the antigen. Under defined conditions virtually 100% of antigen-bearing cultured cells were killed, whereas cells that lacked the antigen were not affected. Conjugates containing toxin A chains coupled to monoclonal antibodies may be useful in studying functions of various cell surface components and, possibly, as tumor-specific therapeutic agents.

Antibody-mediated inhibition of ricin toxin retrograde transport.

PubMed

Yermakova, Anastasiya; Klokk, Tove Irene; Cole, Richard; Sandvig, Kirsten; Mantis, Nicholas J

2014-04-08

Ricin is a member of the ubiquitous family of plant and bacterial AB toxins that gain entry into the cytosol of host cells through receptor-mediated endocytosis and retrograde traffic through the trans-Golgi network (TGN) and endoplasmic reticulum (ER). While a few ricin toxin-specific neutralizing monoclonal antibodies (MAbs) have been identified, the mechanisms by which these antibodies prevent toxin-induced cell death are largely unknown. Using immunofluorescence confocal microscopy and a TGN-specific sulfation assay, we demonstrate that 24B11, a MAb against ricin's binding subunit (RTB), associates with ricin in solution or when prebound to cell surfaces and then markedly enhances toxin uptake into host cells. Following endocytosis, however, toxin-antibody complexes failed to reach the TGN; instead, they were shunted to Rab7-positive late endosomes and LAMP-1-positive lysosomes. Monovalent 24B11 Fab fragments also interfered with toxin retrograde transport, indicating that neither cross-linking of membrane glycoproteins/glycolipids nor the recently identified intracellular Fc receptor is required to derail ricin en route to the TGN. Identification of the mechanism(s) by which antibodies like 24B11 neutralize ricin will advance our fundamental understanding of protein trafficking in mammalian cells and may lead to the discovery of new classes of toxin inhibitors and therapeutics for biodefense and emerging infectious diseases. IMPORTANCE Ricin is the prototypic member of the AB family of medically important plant and bacterial toxins that includes cholera and Shiga toxins. Ricin is also a category B biothreat agent. Despite ongoing efforts to develop vaccines and antibody-based therapeutics against ricin, very little is known about the mechanisms by which antibodies neutralize this toxin. In general, it is thought that antibodies simply prevent toxins from attaching to cell surface receptors or promote their clearance through Fc receptor (FcR)-mediated uptake. In this report, however, we describe a neutralizing monoclonal antibody (MAb) against ricin's binding subunit (RTB) that not only associates with ricin after the toxin has bound to the cell's surface but actually enhances toxin uptake into host cells. Following endocytosis, the antibody-toxin complexes are then routed for degradation. The results of this study are important because they reveal a previously unappreciated role for B-subunit-specific antibodies in intracellular neutralization of ricin toxin.

Surface topography of hairy cell leukemia cells compared to other leukemias as seen by scanning electron microscopy.

PubMed

Polliack, Aaron; Tadmor, Tamar

2011-06-01

This short review deals with the ultrastructural surface architecture of hairy cell leukemia (HCL) compared to other leukemic cells, as seen by scanning electron microscopy (SEM). The development of improved techniques for preparing blood cells for SEM in the 1970s readily enabled these features to be visualized more accurately. This review returns us to the earlier history of SEM, when the surface topography of normal and neoplastic cells was visualized and reported for the first time, in an era before the emergence and use of monoclonal antibodies and flow cytometry, now used routinely to define cells by their immunophenotype. Surface microvilli are characteristic for normal and leukemic lymphoid cells, myelo-monocytic cells lack microvilli and show surface ruffles, while leukemic plasma and myeloma cells and megakaryocytes display large surface blebs. HCL cell surfaces are complex and typically 'hybrid' in nature, displaying both lymphoid and monocytic features with florid ruffles of varying sizes interspersed with clumps of short microvilli cytoplasm. The surface features of other leukemic cells and photomicrographs of immuno-SEM labeling of cells employing antibodies and colloidal gold, reported more than 20 years ago, are shown.

Discovery of high affinity anti-ricin antibodies by B cell receptor sequencing and by yeast display of combinatorial VH:VL libraries from immunized animals.

PubMed

Wang, Bo; Lee, Chang-Han; Johnson, Erik L; Kluwe, Christien A; Cunningham, Josephine C; Tanno, Hidetaka; Crooks, Richard M; Georgiou, George; Ellington, Andrew D

2016-01-01

Ricin is a toxin that could potentially be used as a bioweapon. We identified anti-ricin A chain antibodies by sequencing the antibody repertoire from immunized mice and by selecting high affinity antibodies using yeast surface display. These methods led to the isolation of multiple antibodies with high (sub-nanomolar) affinity. Interestingly, the antibodies identified by the 2 independent approaches are from the same clonal lineages, indicating for the first time that yeast surface display can identify native antibodies. The new antibodies represent well-characterized reagents for biodefense diagnostics and therapeutics development.

A Quartz Crystal Microbalance Immunosensor for Stem Cell Selection and Extraction

PubMed Central

Costanzo, Salvatore; Zambrano, Gerardo; Mauro, Marco; Battaglia, Raffaele; Ferrini, Gianluca; Nastri, Flavia; Pavone, Vincenzo

2017-01-01

A cost-effective immunosensor for the detection and isolation of dental pulp stem cells (DPSCs) based on a quartz crystal microbalance (QCM) has been developed. The recognition mechanism relies on anti-CD34 antibodies, DPSC-specific monoclonal antibodies that are anchored on the surface of the quartz crystals. Due to its high specificity, real time detection, and low cost, the proposed technology has a promising potential in the field of cell biology, for the simultaneous detection and sorting of stem cells from heterogeneous cell samples. The QCM surface was properly tailored through a biotinylated self-assembled monolayer (SAM). The biotin–avidin interaction was used to immobilize the biotinylated anti-CD34 antibody on the gold-coated quartz crystal. After antibody immobilization, a cellular pellet, with a mixed cell population, was analyzed; the results indicated that the developed QCM immunosensor is highly specific, being able to detect and sort only CD34+ cells. Our study suggests that the proposed technology can detect and efficiently sort any kind of cell from samples with high complexity, being simple, selective, and providing for more convenient and time-saving operations. PMID:29182568

Explanation of the Reaction of Monoclonal Antibodies with Candida Albicans Cell Surface in Terms of Compound Poisson Process

NASA Astrophysics Data System (ADS)

Dudek, Mirosław R.; Mleczko, Józef

Surprisingly, still very little is known about the mathematical modeling of peaks in the binding affinities distribution function. In general, it is believed that the peaks represent antibodies directed towards single epitopes. In this paper, we refer to fluorescence flow cytometry experiments and show that even monoclonal antibodies can display multi-modal histograms of affinity distribution. This result take place when some obstacles appear in the paratope-epitope reaction such that the process of reaching the specific epitope ceases to be a point Poisson process. A typical example is the large area of cell surface, which could be unreachable by antibodies leading to the heterogeneity of the cell surface repletion. In this case the affinity of cells to bind the antibodies should be described by a more complex process than the pure-Poisson point process. We suggested to use a doubly stochastic Poisson process, where the points are replaced by a binomial point process resulting in the Neyman distribution. The distribution can have a strongly multinomial character, and with the number of modes depending on the concentration of antibodies and epitopes. All this means that there is a possibility to go beyond the simplified theory, one response towards one epitope. As a consequence, our description provides perspectives for describing antigen-antibody reactions, both qualitatively and quantitavely, even in the case when some peaks result from more than one binding mechanism.

A Role for Small Antibody Fragments to Bind and Neutralize HIV | Center for Cancer Research

Cancer.gov

The surface of the Human Immunodeficiency Virus (HIV) is studded with numerous copies of the glycoprotein Env. Each Env spike is composed of three copies of the proteins gp41, which sits in the viral membrane, and gp120, which rests on top of each gp41 molecule. Env is essential for HIV-mediated infection because the binding of gp120 to the T cell surface receptor CD4 initiates a conformational change in Env exposing the fusion peptide, which inserts into the T cell membrane and helps fuse the T cell and virus together. This makes Env an attractive target for designing therapeutic inhibitory antibodies. However, the complexities of the HIV surface proteins and the tight association of the virus and T cell during infection have hampered the identification of full-length antibodies with effective HIV neutralizing activity.

Polymer-coated surface enhanced Raman scattering (SERS) gold nanoparticles for multiplexed labeling of chronic lymphocytic leukemia cells

NASA Astrophysics Data System (ADS)

MacLaughlin, Christina M.; Parker, Edward P. K.; Walker, Gilbert C.; Wang, Chen

2012-01-01

The ease and flexibility of functionalization and inherent light scattering properties of plasmonic nanoparticles make them suitable contrast agents for measurement of cell surface markers. Immunophenotyping of lymphoproliferative disorders is traditionally undertaken using fluorescence detection methods which have a number of limitations. Herein, surface-enhanced Raman scattering (SERS) gold nanoparticles conjugated to monoclonal antibodies are used for the selective targeting of CD molecules on the surface of chronic lymphocytic leukemia (CLL) cells. Raman-active reporters were physisorbed on to the surface of 60 nm spherical Au nanoparticles, the particles were coated with 5kDa polyethylene glycol (PEG) including functionalities for conjugation to monoclonal IgG1 antibodies. A novel method for quantifying the number of antibodies bound to SERS probes on an individual basis as opposed to obtaining averages from solution was demonstrated using metal dots in transmission electron microscopy (TEM). The specificity of the interaction between SERS probes and surface CD molecules of CLL cells was assessed using Raman spectroscopy and dark field microscopy. An in-depth study of SERS probe targeting to B lymphocyte marker CD20 was undertaken, and proof-of-concept targeting using different SERS nanoparticle dyes specific for cell surface CD19, CD45 and CD5 demonstrated using SERS spectroscopy.

Inhibition of cell surface mediated plasminogen activation by a monoclonal antibody against alpha-Enolase.

PubMed

López-Alemany, Roser; Longstaff, Colin; Hawley, Stephen; Mirshahi, Massoud; Fábregas, Pere; Jardí, Merce; Merton, Elizabeth; Miles, Lindsey A; Félez, Jordi

2003-04-01

Localization of plasmin activity on leukocyte surfaces plays a critical role in fibrinolysis as well as in pathological and physiological processes in which cells must degrade the extracellular matrix in order to migrate. The binding of plasminogen to leukocytic cell lines induces a 30- to 80-fold increase in the rate of plasminogen activation by tissue-type (tPA) and urokinase-type (uPA) plasminogen activators. In the present study we have examined the role of alpha-enolase in plasminogen activation on the cell surface. We produced and characterized a monoclonal antibody (MAb) 11G1 against purified alpha-enolase, which abrogated about 90% of cell-dependent plasminogen activation by either uPA or tPA on leukocytoid cell lines of different lineages: B-lymphocytic, T-lymphocytic, granulocytic, and monocytic cells. In addition, MAb 11G1 also blocked enhancement of plasmin formation by peripheral blood neutrophils and monocytes. In contrast, MAb 11G1 did not affect plasmin generation in the presence of fibrin, indicating that this antibody did not interact with fibrinolytic components in the absence of cells. These data suggest that, although leukocytic cells display several molecules that bind plasminogen, alpha-enolase is responsible for the majority of the promotion of plasminogen activation on the surfaces of leukocytic cells. Copyright 2003 Wiley-Liss, Inc.

Mapping HA-tagged protein at the surface of living cells by atomic force microscopy.

PubMed

Formosa, C; Lachaize, V; Galés, C; Rols, M P; Martin-Yken, H; François, J M; Duval, R E; Dague, E

2015-01-01

Single-molecule force spectroscopy using atomic force microscopy (AFM) is more and more used to detect and map receptors, enzymes, adhesins, or any other molecules at the surface of living cells. To be specific, this technique requires antibodies or ligands covalently attached to the AFM tip that can specifically interact with the protein of interest. Unfortunately, specific antibodies are usually lacking (low affinity and specificity) or are expensive to produce (monoclonal antibodies). An alternative strategy is to tag the protein of interest with a peptide that can be recognized with high specificity and affinity with commercially available antibodies. In this context, we chose to work with the human influenza hemagglutinin (HA) tag (YPYDVPDYA) and labeled two proteins: covalently linked cell wall protein 12 (Ccw12) involved in cell wall remodeling in the yeast Saccharomyces cerevisiae and the β2-adrenergic receptor (β2-AR), a G protein-coupled receptor (GPCR) in higher eukaryotes. We first described the interaction between HA antibodies, immobilized on AFM tips, and HA epitopes, immobilized on epoxy glass slides. Using our system, we then investigated the distribution of Ccw12 proteins over the cell surface of the yeast S. cerevisiae. We were able to find the tagged protein on the surface of mating yeasts, at the tip of the mating projections. Finally, we could unfold multimers of β2-AR from the membrane of living transfected chinese hamster ovary cells. This result is in agreement with GPCR oligomerization in living cell membranes and opens the door to the study of the influence of GPCR ligands on the oligomerization process. Copyright © 2014 John Wiley & Sons, Ltd.

HLA-B27-Homodimer-Specific Antibody Modulates the Expansion of Pro-Inflammatory T-Cells in HLA-B27 Transgenic Rats.

PubMed

Marroquin Belaunzaran, Osiris; Kleber, Sascha; Schauer, Stefan; Hausmann, Martin; Nicholls, Flora; Van den Broek, Maries; Payeli, Sravan; Ciurea, Adrian; Milling, Simon; Stenner, Frank; Shaw, Jackie; Kollnberger, Simon; Bowness, Paul; Petrausch, Ulf; Renner, Christoph

2015-01-01

HLA-B27 is a common genetic risk factor for the development of Spondyloarthritides (SpA). HLA-B27 can misfold to form cell-surface heavy chain homodimers (B272) and induce pro-inflammatory responses that may lead to SpA pathogenesis. The presence of B272 can be detected on leukocytes of HLA-B27+ Ankylosing spondylitis (AS) patients and HLA-B27 transgenic rats. We characterized a novel B272-specific monoclonal antibody to study its therapeutic use in HLA-B27 associated disorders. The monoclonal HD5 antibody was selected from a phage library to target cell-surface B272 homodimers and characterized for affinity, specificity and ligand binding. The immune modulating effect of HD5 was tested in HLA-B27 transgenic rats. Onset and progression of disease profiles were monitored during therapy. Cell-surface B272 and expansion of pro-inflammatory cells from blood, spleen and draining lymph nodes were assessed by flow cytometry. HD5 bound B272 with high specificity and affinity (Kd = 0.32 nM). HD5 blocked cell-surface interaction of B272 with immune regulatory receptors KIR3DL2, LILRB2 and Pirb. In addition, HD5 modulated the production of TNF from CD4+ T-cells by limiting B272 interactions in vitro. In an HLA-B27 transgenic rat model repetitive dosing of HD5 reduced the expansion of pro-inflammatory CD4+ T-cells, and decreased the levels of soluble TNF and number of cell-surface B272 molecules. HD5 predominantly inhibits early TNF production and expansion of pro-inflammatory CD4+ T-cells in HLA-B27 transgenic rats. Monoclonal antibodies targeting cell-surface B272 propose a new concept for the modulation of inflammatory responses in HLA-B27 related disorders.

HLA-B27-Homodimer-Specific Antibody Modulates the Expansion of Pro-Inflammatory T-Cells in HLA-B27 Transgenic Rats

PubMed Central

Marroquin Belaunzaran, Osiris; Kleber, Sascha; Schauer, Stefan; Hausmann, Martin; Nicholls, Flora; Van den Broek, Maries; Payeli, Sravan; Ciurea, Adrian; Milling, Simon; Stenner, Frank; Shaw, Jackie; Kollnberger, Simon; Bowness, Paul; Petrausch, Ulf; Renner, Christoph

2015-01-01

Objectives HLA-B27 is a common genetic risk factor for the development of Spondyloarthritides (SpA). HLA-B27 can misfold to form cell-surface heavy chain homodimers (B272) and induce pro-inflammatory responses that may lead to SpA pathogenesis. The presence of B272 can be detected on leukocytes of HLA-B27+ Ankylosing spondylitis (AS) patients and HLA-B27 transgenic rats. We characterized a novel B272–specific monoclonal antibody to study its therapeutic use in HLA-B27 associated disorders. Methods The monoclonal HD5 antibody was selected from a phage library to target cell-surface B272 homodimers and characterized for affinity, specificity and ligand binding. The immune modulating effect of HD5 was tested in HLA-B27 transgenic rats. Onset and progression of disease profiles were monitored during therapy. Cell-surface B272 and expansion of pro-inflammatory cells from blood, spleen and draining lymph nodes were assessed by flow cytometry. Results HD5 bound B272 with high specificity and affinity (Kd = 0.32 nM). HD5 blocked cell-surface interaction of B272 with immune regulatory receptors KIR3DL2, LILRB2 and Pirb. In addition, HD5 modulated the production of TNF from CD4+ T-cells by limiting B272 interactions in vitro. In an HLA-B27 transgenic rat model repetitive dosing of HD5 reduced the expansion of pro-inflammatory CD4+ T-cells, and decreased the levels of soluble TNF and number of cell-surface B272 molecules. Conclusion HD5 predominantly inhibits early TNF production and expansion of pro-inflammatory CD4+ T-cells in HLA-B27 transgenic rats. Monoclonal antibodies targeting cell-surface B272 propose a new concept for the modulation of inflammatory responses in HLA-B27 related disorders. PMID:26125554

Characterisation of monoclonal antibodies to common protein epitopes on the cell surface of Streptococcus mutans and Streptococcus sobrinus.

PubMed

Smith, R; Lehner, T

1989-09-01

Three monoclonal antibodies (MAb) were prepared against a cell surface antigen which cross-react between Streptococcus mutans (serotypes c, e and f) and Streptococcus sobrinus (serotypes d and g). Two of the MAb also recognise a determinant on the surface of Streptococcus cricetus (serotype a). The common antigen shared between S. mutans and S. sobrinus was demonstrated by Western blotting to be about 200 kD in size. This antigen is shared not only by the cell surfaces of serotypes a, c, d, e, f and g, but also by the major cell surface antigen of S. mutans of 185 kD and another of 150 kD. These MAb identify all but one mutans type of streptococci and can be utilised as analytical reagents.

Monoclonal antibodies directed against surface molecules of multicell spheroids

NASA Technical Reports Server (NTRS)

Martinez, Andrew O.

1993-01-01

The objective of this project is to generate a library of monoclonal antibodies (MAbs) to surface molecules of mammalian tumor and transformed cells grown as multicell spheroids (MCS). These MCS are highly organized, three dimensional multicellular structures which exhibit many characteristics of in vivo organized tissues not found in conventional monolayer or suspension culture; therefore, MCS make better in vitro model systems to study the interactions of mammalian cells. Additionally, they provide a functional assay for surface adhesion molecules.

When No Response Is a Good Thing | Center for Cancer Research

Cancer.gov

Custom-designed therapies that target cell-surface antigens or receptors represent a promising immunological approach in cancer therapy. Antibodies that bind these targets are the starting point.  Potent toxins can then be added to them by fusing antibody fragments to powerful bacterial toxins such as Pseudomonas exotoxin (PE). This recombinant immunotoxin combines antibody selectivity with toxin cell-killing potency.

Development and characterization of a camelid single-domain antibody directed to human CD22 biomarker.

PubMed

Faraji, Fatemeh; Tajik, Nader; Behdani, Mahdi; Shokrgozar, Mohammad Ali; Zarnani, Amir Hassan; Shahhosseini, Fatemeh; Habibi-Anbouhi, Mahdi

2018-03-15

CD22 is a B-cell-specific trans-membrane glycoprotein, which is found on the surface of the most B cells and modulates their function, survival, and apoptosis. Recently, targeting this cell surface biomarker in B-cell malignancies and disorders has attracted a lot of attention. The variable domain of camelid single-chain antibodies (VHH, nanobody) is a form of antibodies with novel properties including small size (15-17 kDa), thermal and chemical stability, high affinity and homology to human antibody sequences. In this study, a novel anti-CD22-specific VHH (Nb) has been developed and characterized by the screening of an immunized phage display library and its binding to CD22 + B cells is evaluated. Produced anti-CD22 VHH had a single protein band about 17 kDa of molecular size in Western blotting and its binding affinity was approximately 9 × 10 -9  M. Also, this product had high specificity and it was able to recognize the natural CD22 antigen in CD22+ cell lysate as well as on the cell surface (93%). This anti-CD22 VHH with both high affinity and specificity recognizes CD22 antigen well and can be used in diagnosis and treatment of B cell disorders and malignancies. © 2018 International Union of Biochemistry and Molecular Biology, Inc.

Baculovirus display of functional antibody Fab fragments.

PubMed

Takada, Shinya; Ogawa, Takafumi; Matsui, Kazusa; Suzuki, Tasuku; Katsuda, Tomohisa; Yamaji, Hideki

2015-08-01

The generation of a recombinant baculovirus that displays antibody Fab fragments on the surface was investigated. A recombinant baculovirus was engineered so that the heavy chain (Hc; Fd fragment) of a mouse Fab fragment was expressed as a fusion to the N-terminus of baculovirus gp64, while the light chain of the Fab fragment was simultaneously expressed as a secretory protein. Following infection of Sf9 insect cells with the recombinant baculovirus, the culture supernatant was analyzed by enzyme-linked immunosorbent assay using antigen-coated microplates and either an anti-mouse IgG or an anti-gp64 antibody. A relatively strong signal was obtained in each case, showing antigen-binding activity in the culture supernatant. In western blot analysis of the culture supernatant using the anti-gp64 antibody, specific protein bands were detected at an electrophoretic mobility that coincided with the molecular weight of the Hc-gp64 fusion protein as well as that of gp64. Flow cytometry using a fluorescein isothiocyanate-conjugated antibody specific to mouse IgG successfully detected the Fab fragments on the surface of the Sf9 cells. These results suggest that immunologically functional antibody Fab fragments can be displayed on the surface of baculovirus particles, and that a fluorescence-activated cell sorter with a fluorescence-labeled antigen can isolate baculoviruses displaying specific Fab fragments. This successful baculovirus display of antibody Fab fragments may offer a novel approach for the efficient selection of specific antibodies.

Neuronal surface antigen antibodies in limbic encephalitis

PubMed Central

Graus, F; Saiz, A; Lai, M; Bruna, J; López, F; Sabater, L; Blanco, Y; Rey, M J.; Ribalta, T; Dalmau, J

2008-01-01

Objective: To report the frequency and type of antibodies against neuronal surface antigens (NSA-ab) in limbic encephalitis (LE). Methods: Analysis of clinical features, neuropathologic findings, and detection of NSA-ab using immunochemistry on rat tissue and neuronal cultures in a series of 45 patients with paraneoplastic (23) or idiopathic (22) LE. Results: NSA-ab were identified in 29 patients (64%; 12 paraneoplastic, 17 idiopathic). Thirteen patients had voltage-gated potassium channels (VGKC)-ab, 11 novel NSA (nNSA)-ab, and 5 NMDA receptor (NMDAR)-ab. nNSA-ab did not identify a common antigen and were more frequent in paraneoplastic than idiopathic LE (39% vs 9%; p = 0.03). When compared with VGKC-ab or NMDAR-ab, the nNSA associated more frequently with intraneuronal antibodies (11% vs 73%; p = 0.001). Of 12 patients (9 nNSA-ab, 2 VGKC-ab, 1 NMDAR-ab) with paraneoplastic LE and NSA-ab, concomitant intraneuronal antibodies occurred in 9 (75%). None of these 12 patients improved with immunotherapy. The autopsy of three of them showed neuronal loss, microgliosis, and cytotoxic T cell infiltrates in the hippocampus and amygdala. These findings were compatible with a T-cell mediated neuronal damage. In contrast, 13 of 17 (76%) patients with idiopathic LE and NSA-ab (8 VGKC-ab, 4 NMDAR-ab, 1 nNSA-ab) and 1 of 5 (20%) without antibodies had clinical improvement (p = 0.04). Conclusions: In paraneoplastic limbic encephalitis (LE), novel antibodies against neuronal surface antigens (nNSA-ab) occur frequently, coexist with antibodies against intracellular antigens, and these cases are refractory to immunotherapy. In idiopathic LE, the likelihood of improvement is significantly higher in patients with NSA-ab than in those without antibodies. GLOSSARY GAD = glutamic acid decarboxylase; LE = limbic encephalitis; NMDAR = N-methyl-D-aspartate receptor; NSA = neuronal surface antigens; nNSA = novel NSA; SCLC = small-cell lung cancer; VGKC = voltage-gated potassium channels; WBC = white blood cells. PMID:18794496

Isolation of mouse pancreatic alpha, beta, duct and acinar populations with cell surface markers.

PubMed

Dorrell, Craig; Grompe, Maria T; Pan, Fong Cheng; Zhong, Yongping; Canaday, Pamela S; Shultz, Leonard D; Greiner, Dale L; Wright, Chris V; Streeter, Philip R; Grompe, Markus

2011-06-06

Tools permitting the isolation of live pancreatic cell subsets for culture and/or molecular analysis are limited. To address this, we developed a collection of monoclonal antibodies with selective surface labeling of endocrine and exocrine pancreatic cell types. Cell type labeling specificity and cell surface reactivity were validated on mouse pancreatic sections and by gene expression analysis of cells isolated using FACS. Five antibodies which marked populations of particular interest were used to isolate and study viable populations of purified pancreatic ducts, acinar cells, and subsets of acinar cells from whole pancreatic tissue or of alpha or beta cells from isolated mouse islets. Gene expression analysis showed the presence of known endocrine markers in alpha and beta cell populations and revealed that TTR and DPPIV are primarily expressed in alpha cells whereas DGKB and GPM6A have a beta cell specific expression profile. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Anti-dsDNA Antibodies Bind to Mesangial Annexin II in Lupus Nephritis

PubMed Central

Yung, Susan; Cheung, Kwok Fan; Zhang, Qing

2010-01-01

Production of anti-dsDNA antibodies is a hallmark of lupus nephritis, but how these antibodies deposit in organs and elicit inflammatory damage remains unknown. In this study, we sought to identify antigens on the surface of human mesangial cells (HMC) that mediate the binding of human anti-dsDNA antibodies and the subsequent pathogenic processes. We isolated anti-dsDNA antibodies from patients with lupus nephritis by affinity chromatography. We used multiple methods to identify and characterize antigens from the plasma membrane fraction of mesangial cells that crossreacted with the anti-dsDNA antibodies. We found that annexin II mediated the binding of anti-dsDNA antibodies to HMC. After binding to the mesangial cell surface, anti-dsDNA antibodies were internalized into the cytoplasm and nucleus. This also led to induction of IL-6 secretion and annexin II synthesis, mediated through activation of p38 MAPK, JNK, and AKT. Binding of anti-dsDNA antibodies to annexin II correlated with disease activity in human lupus nephritis. Glomerular expression of annexin II correlated with the severity of nephritis, and annexin II colocalized with IgG and C3 deposits in both human and murine lupus nephritis. Gene silencing of annexin II in HMC reduced binding of anti-dsDNA antibody and partially decreased IL-6 secretion. In summary, our data demonstrate that annexin II mediates the binding of anti-dsDNA antibodies to mesangial cells, contributing to the pathogenesis of lupus nephritis. This interaction provides a potential target for therapeutic intervention. PMID:20847146

Fluorescent immunolabeling of cancer cells by quantum dots and antibody scFv fragment.

PubMed

Zdobnova, Tatiana A; Dorofeev, Sergey G; Tananaev, Piter N; Vasiliev, Roman B; Balandin, Taras G; Edelweiss, Eveline F; Stremovskiy, Oleg A; Balalaeva, Irina V; Turchin, Ilya V; Lebedenko, Ekaterina N; Zlomanov, Vladimir P; Deyev, Sergey M

2009-01-01

Semiconductor quantum dots (QDs) coupled with cancer-specific targeting ligands are new promising agents for fluorescent visualization of cancer cells. Human epidermal growth factor receptor 2/neu (HER2/neu), overexpressed on the surface of many cancer cells, is an important target for cancer diagnostics. Antibody scFv fragments as a targeting agent for direct delivery of fluorophores offer significant advantages over full-size antibodies due to their small size, lower cross-reactivity, and immunogenicity. We have used quantum dots linked to anti-HER2/neu 4D5 scFv antibody to label HER2/neu-overexpressing live cells. Labeling of target cells was shown to have high brightness, photostability, and specificity. The results indicate that construction based on quantum dots and scFv antibody can be successfully used for cancer cell visualization.

Conatumumab (AMG 655) coated nanoparticles for targeted pro-apoptotic drug delivery.

PubMed

Fay, Francois; McLaughlin, Kirsty M; Small, Donna M; Fennell, Dean A; Johnston, Patrick G; Longley, Daniel B; Scott, Christopher J

2011-11-01

Colloidal nanoparticle drug delivery systems have attracted much interest for their ability to enable effective formulation and delivery of therapeutic agents. The selective delivery of these nanoparticles to the disease site can be enhanced by coating the surface of the nanoparticles with targeting moieties, such as antibodies. In this current work, we demonstrate that antibodies on the surface of the particles can also elicit key biological effects. Specifically, we demonstrate the induction of apoptosis in colorectal HCT116 cancer cells using PLGA nanoparticles coated with Conatumumab (AMG 655) death receptor 5-specific antibodies (DR5-NP). We show that DR5-NP preferentially target DR5-expressing cells and present a sufficient density of antibody paratopes to induce apoptosis via DR5, unlike free AMG 655 or non-targeted control nanoparticles. We also demonstrate that DR5-targeted nanoparticles encapsulating the cytotoxic drug camptothecin are effectively targeted to the tumour cells, thereby producing enhanced cytotoxic effects through simultaneous drug delivery and apoptosis induction. These results demonstrate that antibodies on nanoparticulate surfaces can be exploited for dual modes of action to enhance the therapeutic utility of the modality. Copyright © 2011 Elsevier Ltd. All rights reserved.

Translation and Clinical Development of Bispecific T‐cell Engaging Antibodies for Cancer Treatment

PubMed Central

Yuraszeck, T; Kasichayanula, S

2017-01-01

Bispecific T‐cell Engagers (BiTE®) antibody constructs enable a polyclonal T‐cell response to cell‐surface tumor‐associated antigens, bypassing the narrow specificities of T‐cell receptors and the need for antigen presentation through the major histocompatibility complex pathways. Blinatumomab, a CD19xCD3 BiTE® antibody construct, received accelerated approval for the treatment of relapsed/refractory Philadelphia chromosome negative acute lymphoblastic leukemia. Herein we review the pharmacology, safety, and efficacy observed in studies of blinatumomab and other BiTE® antibody constructs. Quantitative systems pharmacology is envisioned as a means to optimize dosing decisions for trials in which BiTE® antibody constructs are administered as monotherapy or in combination with other immunotherapies. PMID:28182247

Preparation of poly-L-lysine functionalized magnetic nanoparticles and their influence on viability of cancer cells

NASA Astrophysics Data System (ADS)

Khmara, I.; Koneracka, M.; Kubovcikova, M.; Zavisova, V.; Antal, I.; Csach, K.; Kopcansky, P.; Vidlickova, I.; Csaderova, L.; Pastorekova, S.; Zatovicova, M.

2017-04-01

This study was aimed at development of biocompatible amino-functionalized magnetic nanoparticles as carriers of specific antibodies able to detect and/or target cancer cells. Poly-L-lysine (PLL)-modified magnetic nanoparticle samples with different PLL/Fe3O4 content were prepared and tested to define the optimal PLL/Fe3O4 weight ratio. The samples were characterized for particle size and morphology (SEM, TEM and DLS), and surface properties (zeta potential measurements). The optimal PLL/Fe3O4 weight ratio of 1.0 based on both zeta potential and DLS measurements was in agreement with the UV/VIS measurements. Magnetic nanoparticles with the optimal PLL content were conjugated with antibody specific for the cancer biomarker carbonic anhydrase IX (CA IX), which is induced by hypoxia, a physiologic stress present in solid tumors and linked with aggressive tumor behavior. CA IX is localized on the cell surface with the antibody-binding epitope facing the extracellular space and is therefore suitable for antibody-based targeting of tumor cells. Here we showed that PLL/Fe3O4 magnetic nanoparticles exhibit cytotoxic activities in a cell type-dependent manner and bind to cells expressing CA IX when conjugated with the CA IX-specific antibody. These data support further investigations of the CA IX antibody-conjugated, magnetic field-guided/activated nanoparticles as tools in anticancer strategies.

Chinese Medicine Amygdalin and β-Glucosidase Combined with Antibody Enzymatic Prodrug System As A Feasible Antitumor Therapy.

PubMed

Li, Yun-Long; Li, Qiao-Xing; Liu, Rui-Jiang; Shen, Xiang-Qian

2018-03-01

Amarogentin is an efficacious Chinese herbal medicine and a component of the bitter apricot kernel. It is commonly used as an expectorant and supplementary anti-cancer drug. β-Glucosidase is an enzyme that hydrolyzes the glycosidic bond between aryl and saccharide groups to release glucose. Upon their interaction, β-glucosidase catalyzes amarogentin to produce considerable amounts of hydrocyanic acid, which inhibits cytochrome C oxidase, the terminal enzyme in the mitochondrial respiration chain, and suspends adenosine triphosphate synthesis, resulting in cell death. Hydrocyanic acid is a cell-cycle-stage-nonspecific agent that kills cancer cells. Thus, β-glucosidase can be coupled with a tumor-specific monoclonal antibody. β-Glucosidase can combine with cancer-cell-surface antigens and specifically convert amarogentin to an active drug that acts on cancer cells and the surrounding antibodies to achieve a killing effect. β-Glucosidase is injected intravenously and recognizes cancer-cell-surface antigens with the help of an antibody. The prodrug amarogentin is infused after β-glucosidase has reached the target position. Coupling of cell membrane peptides with β-glucosidase allows the enzyme to penetrate capillary endothelial cells and clear extracellular deep solid tumors to kill the cells therein. The Chinese medicine amarogentin and β-glucosidase will become an important treatment for various tumors when an appropriate monoclonal antibody is developed.

Development of Raman Spectroscopy as a Clinical Diagnostic Tool

NASA Astrophysics Data System (ADS)

Borel, Santa

Raman spectroscopy is the collection of inelastically scattered light in which the spectra contain biochemical information of the probed cells or tissue. This work presents both targeted and untargeted ways that the technique can be exploited in biological samples. First, surface enhanced Raman scattering (SERS) gold nanoparticles conjugated to targeting antibodies were shown to be successful for multiplexed detection of overexpressed surface antigens in lung cancer cell lines. Further work will need to optimize the conjugation technique to preserve the strong binding affinity of the antibodies. Second, untargeted Raman microspectroscopy combined with multivariate statistical analysis was able to successfully differentiate mouse ovarian surface epithelial (MOSE) cells and spontaneously transformed ovarian surface epithelial (STOSE) cells with high accuracy. The differences between the two groups were associated with increased nucleic acid content in the STOSE cells. This shows potential for single cell detection of ovarian cancer.

Quantitative blood group typing using surface plasmon resonance.

PubMed

Then, Whui Lyn; Aguilar, Marie-Isabel; Garnier, Gil

2015-11-15

The accurate and reliable typing of blood groups is essential prior to blood transfusion. While current blood typing methods are well established, results are subjective and heavily reliant on analysis by trained personnel. Techniques for quantifying blood group antibody-antigen interactions are also very limited. Many biosensing systems rely on surface plasmon resonance (SPR) detection to quantify biomolecular interactions. While SPR has been widely used for characterizing antibody-antigen interactions, measuring antibody interactions with whole cells is significantly less common. Previous studies utilized SPR for blood group antigen detection, however, showed poor regeneration causing loss of functionality after a single use. In this study, a fully regenerable, multi-functional platform for quantitative blood group typing via SPR detection is achieved by immobilizing anti-human IgG antibody to the sensor surface, which binds to the Fc region of human IgG antibodies. The surface becomes an interchangeable platform capable of quantifying the blood group interactions between red blood cells (RBCs) and IgG antibodies. As with indirect antiglobulin tests (IAT), which use IgG antibodies for detection, IgG antibodies are initially incubated with RBCs. This facilitates binding to the immobilized monolayer and allows for quantitative blood group detection. Using the D-antigen as an example, a clear distinction between positive (>500 RU) and negative (<100 RU) RBCs is achieved using anti-D IgG. Complete regeneration of the anti-human IgG surface is also successful, showing negligible degradation of the surface after more than 100 regenerations. This novel approach is validated with human-sourced whole blood samples to demonstrate an interesting alternative for quantitative blood grouping using SPR analysis. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Wall teichoic acids prevent antibody binding to epitopes within the cell wall of Staphylococcus aureus.

PubMed

Gautam, Samir; Kim, Taehan; Lester, Evan; Deep, Deeksha; Spiegel, David A

2016-01-15

Staphylococcus aureus is a Gram-positive bacterial pathogen that produces a range of infections including cellulitis, pneumonia, and septicemia. The principle mechanism in antistaphylococcal host defense is opsonization with antibodies and complement proteins, followed by phagocytic clearance. Here we use a previously developed technique for installing chemical epitopes in the peptidoglycan cell wall to show that surface glycopolymers known as wall teichoic acids conceal cell wall epitopes, preventing their recognition and opsonization by antibodies. Thus, our results reveal a previously unrecognized immunoevasive role for wall teichoic acids in S. aureus: repulsion of peptidoglycan-targeted antibodies.

Rod outer segment-associated N-acetylgalactosaminylphosphotransferase.

PubMed

Sweatt, A J; Balsamo, J; Lilien, J

1995-01-01

To determine the exact location of a cell surface glycosyltransferase (N-acetylgalactosaminylphosphotransferase, (GalNAcPTase) immunochemically identified in mammalian rod outer segments (ROS), to determine whether anti-GalNAcPTase antibody recognizes retinal molecules that possess transferase activity and to characterize ROS transferase enzyme activity and acceptors. The GalNAcPTase is known to be associated with the adhesion molecule N-cadherin in embryonic avian retinas and with E-cadherin in mammalian pancreatic islet cells. Purified, fixed ROS were reacted with anti-chick GalNAcPTase antibody followed by secondary antibody conjugated to colloidal gold and were examined by electron microscopy. Fractions of retinal and ROS proteins enriched in the transferase were obtained through batch adsorption on Sepharose, separated by gel electrophoresis, transferred to nitrocellulose, and either reacted with anti-GalNAcPTase antibody or assayed for transferase activity. Interphotoreceptor matrix (IPM) was examined for the presence of immunoreactive GalNAcPTase by gel electrophoresis and immunoblot. The kinetics and endogenous acceptors of the cow ROS transferase were characterized. ROS are specifically labeled by anti-GalNAcPTase antibody at the cell surface. The immunogold label was associated with the cell surface and with flocculent material adherent to the cell surface. In addition, soluble and particulate fractions of the IPM showed GalNAcPTase-like immunoreactivity. The transferase appears as single immunoreactive band at or near 220 kd. Transferase enzyme activity was present at this position on Western transfers of retinal and ROS proteins. In whole ROS, transferase activity was directed toward endogenous acceptors of very high molecular mass. The GalNAcPTase is localized on ROS in association with the cell surface and with components of the IPM. The molecule recognized by the anti-GalNAcPTase antibody possesses transferase activity toward itself and a few other proteins, but mostly toward very large molecules that may be IPM proteoglycans. It is not yet known whether the enzyme of the adult retina specifically transfers sugar or sugar-phosphate groups to its acceptors. It is proposed that the ROS GalNAcPTase is involved in the modulation of adhesive phenomena between or within photoreceptors or between photoreceptors and the interphotoreceptor matrix.

Using an improved phagocytosis assay to evaluate the effect of HIV on specific antibodies to pregnancy-associated malaria.

PubMed

Ataíde, Ricardo; Hasang, Wina; Wilson, Danny W; Beeson, James G; Mwapasa, Victor; Molyneux, Malcolm E; Meshnick, Steven R; Rogerson, Stephen J

2010-05-25

Pregnant women residing in malaria endemic areas are highly susceptible to Plasmodium falciparum malaria, particularly during their first pregnancy, resulting in low birth weight babies and maternal anaemia. This susceptibility is associated with placental sequestration of parasitised red blood cells expressing pregnancy-specific variant surface antigens. Acquisition of antibodies against these variant surface antigens may protect women and their offspring. Functions of such antibodies may include prevention of placental sequestration or opsonisation of parasitised cells for phagocytic clearance. Here we report the development and optimisation of a new high-throughput flow cytometry-based phagocytosis assay using undifferentiated Thp-1 cells to quantitate the amount of opsonizing antibody in patient sera, and apply this assay to measure the impact of HIV on the levels of antibodies to a pregnancy malaria-associated parasite line in a cohort of Malawian primigravid women. The assay showed high reproducibility, with inter-experimental correlation of r(2) = 0.99. In primigravid women, concurrent malaria infection was associated with significantly increased antibodies, whereas HIV decreased the ability to acquire opsonising antibodies (Mann-Whitney ranksum: p = 0.013). This decrease was correlated with HIV-induced immunosuppression, with women with less than 350 x 10(6) CD4+ T- cells/L having less opsonising antibodies (coef: -11.95,P = 0.002). Levels of antibodies were not associated with protection from low birth weight or anaemia. This flow cytometry-based phagocytosis assay proved to be efficient and accurate for the measurement of Fc-receptor mediated phagocytosis-inducing antibodies in large cohorts. HIV was found to affect mainly the acquisition of antibodies to pregnancy-specific malaria in primigravidae. Further studies of the relationship between opsonising antibodies to malaria in pregnancy and HIV are indicated.

Capture and On-chip analysis of Melanoma Cells Using Tunable Surface Shear forces

NASA Astrophysics Data System (ADS)

Tsao, Simon Chang-Hao; Vaidyanathan, Ramanathan; Dey, Shuvashis; Carrascosa, Laura G.; Christophi, Christopher; Cebon, Jonathan; Shiddiky, Muhammad J. A.; Behren, Andreas; Trau, Matt

2016-01-01

With new systemic therapies becoming available for metastatic melanoma such as BRAF and PD-1 inhibitors, there is an increasing demand for methods to assist with treatment selection and response monitoring. Quantification and characterisation of circulating melanoma cells (CMCs) has been regarded as an excellent non-invasive candidate but a sensitive and efficient tool to do these is lacking. Herein we demonstrate a microfluidic approach for melanoma cell capture and subsequent on-chip evaluation of BRAF mutation status. Our approach utilizes a recently discovered alternating current electrohydrodynamic (AC-EHD)-induced surface shear forces, referred to as nanoshearing. A key feature of nanoshearing is the ability to agitate fluid to encourage contact with surface-bound antibody for the cell capture whilst removing nonspecific cells from the surface. By adjusting the AC-EHD force to match the binding affinity of antibodies against the melanoma-associated chondroitin sulphate proteoglycan (MCSP), a commonly expressed melanoma antigen, this platform achieved an average recovery of 84.7% from biological samples. Subsequent staining with anti-BRAFV600E specific antibody enabled on-chip evaluation of BRAFV600E mutation status in melanoma cells. We believe that the ability of nanoshearing-based capture to enumerate melanoma cells and subsequent on-chip characterisation has the potential as a rapid screening tool while making treatment decisions.

Ultrastructural localization of human HL-A membrane antigens by use of hybrid antibodies

PubMed Central

Neauport-Sautes, Catherine; Silvestre, Daniele; Niccolai, Marie-Gabrielle; Kourilsky, F. M.; Levy, J. P.

1972-01-01

The localization of HL-A histocompatibility antigens at the surface of human lymphocytes in electron microscopy has been studied using hybrid antibodies to bind electron-dense particles (ferritin and plant viruses) to anti-HL-A antibody. A discontinuous distribution of the markers is observed at the cell surface, which is identical with that described for H-2 antigens on mouse lymphocytes with the same technique. Double labelling experiments suggest that the areas of the cell surface where HL-A antigens are detected contain also the heterologous lymphocyte antigens detected by an anti-thymocyte serum and that HL-A antigens are not renewed at a detectable level during the period of the labelling procedure in the areas of the cell surface which are not labelled primarily with ferritin-anti-IgG-anti-HL-A complexes. The interpretation of the discontinuous labelling of HL-A antigens with direct immunoferritin techniques is discussed. ImagesFIG. 2FIG. 3FIG. 4FIG. 5 PMID:5063188

Human hybrid hybridoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiebout, R.F.; van Boxtel-Oosterhof, F.; Stricker, E.A.M.

1987-11-15

Hybrid hybridomas are obtained by fusion of two cells, each producing its own antibody. Several authors have reported the construction of murine hybrid hybridomas with the aim to obtain bispecific monoclonal antibodies. The authors have investigated, in a model system, the feasibility of constructing a human hybrid hybridoma. They fused two monoclonal cell lines: an ouabain-sensitive and azaserine/hypoxanthine-resistant Epstein-Barr virus-transformed human cell line that produces an IgG1kappa antibody directed against tetanus toxiod and an azaserine/hypoxanthine-sensitive and ouabain-resistant human-mouse xenohybrid cell line that produces a human IgG1lambda antibody directed against hepatitis-B surface antigen. Hybrid hybridoma cells were selected in culture mediummore » containing azaserine/hypoxanthine and ouabain. The hybrid nature of the secreted antibodies was analyzed by means of two antigen-specific immunoassay. The results show that it is possible, with the combined use of transformation and xenohybridization techniques, to construct human hybrid hybridomas that produce bispecific antibodies. Bispecific antibodies activity was measured by means of two radioimmunoassays.« less

Rat Muc4 (sialomucin complex) reduces binding of anti-ErbB2 antibodies to tumor cell surfaces, a potential mechanism for herceptin resistance.

PubMed

Price-Schiavi, Shari A; Jepson, Scott; Li, Peter; Arango, Maria; Rudland, Philip S; Yee, Lisa; Carraway, Kermit L

2002-06-20

Muc4 (also called sialomucin complex), the rat homolog of human MUC4, is a heterodimeric glycoprotein complex that consists of a peripheral O-glycosylated mucin subunit, ASGP-1, tightly but noncovalently linked to a N-glycosylated transmembrane subunit, ASGP-2. The complex is expressed in a number of normal, vulnerable epithelial tissues, including mammary gland, uterus, colon, cornea and trachea. Muc4/SMC is also overexpressed or aberrantly expressed on a number of human tumors including breast tumors. Overexpression of Muc4/SMC has been shown to block cell-cell and cell-matrix interactions, protect tumor cells from immune surveillance and promote metastasis. In addition, as a ligand for ErbB2, Muc4/SMC can potentiate phosphorylation of ErbB2 and potentially alter signals generated from this receptor. Using A375 human melanoma cells and MCF7 human breast adenocarcinoma cells stably transfected with tetracycline regulatable Muc4, we have investigated whether overexpression of Muc4/SMC can repress antibody binding to cell surface-expressed ErbB2. Overexpression of Muc4/SMC does not affect the level of ErbB2 expression in either cell line, but it does reduce binding of a number of anti-ErbB2 antibodies, including Herceptin. Interestingly, overexpression of ErbB2 does not block binding of other unrelated antibodies of the same isotype, suggesting that the reduction in ErbB2 antibody binding is due to complex formation of Muc4/SMC and ErbB2. Furthermore, capping of Muc4/SMC with anti-Muc4/SMC antibodies reduces antibody binding to ErbB2 instead of increasing binding, again suggesting that reduced antibody binding to ErbB2 is due to steric hindrance from complex formation of Muc4/SMC and ErbB2. Thus, overexpression of Muc4/SMC on tumor cells may have both prognostic and therapeutic relevance. Copyright 2002 Wiley-Liss, Inc.

Targeting Prostate Cancer Stemlike Cells through Cell Surface Expressed GRP78

DTIC Science & Technology

2016-12-01

NOTES 14. ABSTRACT This study investigated a function for cell surface GRP78 in regulating prostate cancer stem -like cells . In year 1, we showed that...enrichment of cell surface GRP78+ cancer stem like cells in sphere culture. We also showed that the signaling axis activated by cell surface GRP78 is...but not the GRP78(-) cells , exhibited cancer stem -like cell behavior. Furthermore an GRP78 monoclonal antibody inhibited sphere forming ability of

Uptake and intracellular processing of PEG-liposomes and PEG-immunoliposomes by kupffer cells in vitro 1 *.

PubMed

Koning, G A; Morselt, H W; Kamps, J A; Scherphof, G L

2001-01-01

Specific targeting of drugs to for instance tumors or sites of inflammation may be achieved by means of immunoliposomes carrying site-specific antibodies on their surface. The presence of these antibodies may adversely affect the circulation kinetics of such liposomes as a result of interactions with cells of the mononuclear phagocyte system (MPS), mainly represented by macrophages in liver and spleen. The additional insertion of poly(ethylene glycol) chains on the surface of the immunoliposomes may, however, attenuate this effect. We investigated the influence of surface-coupled rat or rabbit antibodies and of PEG on the uptake of liposomes by rat Kupffer cells in culture with (3)H-cholesteryloleyl ether as a metabolically stable marker. Additionally, we assessed the effects of surface-bound IgG and PEG on the intracellular processing of the liposomes by the Kupffer cells, based on a double-label assay using the (3)H-cholesteryl ether as an absolute measure for liposome uptake and the hydrolysis of the degradable marker cholesteryl-(14)C-oleate as relative measure of degradation. Attachment of both rat and rabbit antibodies to PEG-free liposomes caused a several-fold increase in apparent size. The uptake by Kupffer cells, however, was 3-4 fold higher for the rat than for the rabbit IgG liposomes. The presence of PEG drastically reduced the difference between these liposome types. Uptake of liposomes without antibodies amounted to only about 10% (non-PEGylated) or less (PEGylated) of that of the immunoliposomes. In contrast to the marked effects of IgG and PEG on Kupffer cell uptake, the rate of intracellular processing of the liposomes remained virtually unaffected by the presence of these substances on the liposomal surface. These observations are discussed with respect to the design of optimally formulated liposomal drug preparations, combining maximal therapeutic efficacy with minimal toxicity.

Human monoclonal antibodies reactive with human myelomonocytic leukemia cells.

PubMed

Posner, M R; Santos, D J; Elboim, H S; Tumber, M B; Frackelton, A R

1989-04-01

Peripheral blood mononuclear cells from a patient with chronic myelogenous leukemia (CML), in remission, were depleted of CD8-positive T-cells and cultured with Epstein-Barr virus. Four of 20 cultures (20%) secreted human IgG antibodies selectively reactive with the cell surfaces of certain human leukemia cell lines. Three polyclonal, Epstein-Barr virus-transformed, B-cell lines were expanded and fused with the human-mouse myeloma analogue HMMA2.11TG/O. Antibody from secreting clones HL 1.2 (IgG1), HL 2.1 (IgG3), and HL 3.1 (IgG1) have been characterized. All three react with HL-60 (promyelocytic), RWLeu4 (CML promyelocytic), and U937 (monocytic), but not with KG-1 (myeloblastic) or K562 (CML erythroid). There is no reactivity with T-cell lines, Burkitt's cell lines, pre-B-leukemia cell lines, or an undifferentiated CML cell line, BV173. Leukemic cells from two of seven patients with acute myelogenous leukemia and one of five with acute lymphocytic leukemia react with all three antibodies. Normal lymphocytes, monocytes, polymorphonuclear cells, red blood cells, bone marrow cells, and platelets do not react. Samples from patients with other diverse hematopoietic malignancies showed no reactivity. Immunoprecipitations suggest that the reactive antigen(s) is a lactoperoxidase iodinatable series of cell surface proteins with molecular weights of 42,000-54,000 and a noniodinatable protein with a molecular weight of 82,000. Based on these data these human monoclonal antibodies appear to react with myelomonocytic leukemic cells and may detect a leukemia-specific antigen or a highly restricted differentiation antigen.

Cytochrome P450IID6 recognized by LKM1 antibody is not exposed on the surface of hepatocytes.

PubMed

Yamamoto, A M; Mura, C; De Lemos-Chiarandini, C; Krishnamoorthy, R; Alvarez, F

1993-06-01

LKM1 autoantibody, directed against P450IID6, is accepted as a marker of a particular type of autoimmune hepatitis, but its role in the pathogenesis of the disease is controversial. Localization of P450IID6 on the cell surface of rat hepatocytes was previously reported, suggesting that membrane-bound P450IID6 could be the target of LKM1 antibodies, thus allowing immune lysis of hepatocytes. The objective of the present study was to determine, using various methods, the cell localization of P450IID6 in human and rat hepatocytes. Incubation of rat and human hepatocytes with LKM1-positive serum showed slight, if any, cell membrane staining using immunofluorescence, immunoperoxidase and immunoelectron microscopic studies. No staining of the plasma membrane of human hepatocytes was observed when incubations were carried out with immunoaffinity-purified antibody directed against peptide 254-271, the main epitope of P450IID6 recognized by all LKM1 sera tested. Chinese hamster ovary cells, transfected with the complete P450IID6 cDNA and incubated with the supernatant from a B cell lymphoblastoid cell line prepared with the lymphocytes of a LKM1-positive patient, did not show any staining of the cell surface by immunofluorescence. Incubation of rat microsomal fraction vesicles with LKM1-positive serum, followed by protein A-gold immunoelectron microscopy, displayed a staining of almost all vesicles, confirming that P450IID6 is present on the cytoplasmic side of the microsomal membrane, which makes it unable to be expressed on the cell surface even if it were transported from the endoplasmic reticulum (ER). Sulpho NHS Biotin labelling of rat hepatocyte cell membranes did not show the presence of a 50-kD molecule that could have reacted with LKM1 antibody. DNA sequencing of exon 1 of the CYP2D6 gene of a patient positive for LKM1 antibody did not show any difference from that of the normal published sequence of the gene. This does not favour an alteration of the NH2 terminal sequence of the P450IID6 molecule that could explain a translocation of the molecule to the luminal side of the ER, allowing its expression on the cell surface. These results indicate that, in all likelihood, P450IID6 molecule is not present on the cell surface of normal rat and human hepatocytes. Other mechanisms than antibody-mediated cell lysis directed against membrane P450IID6 antigenic determinants must be found to account for the destruction of hepatocytes observed in this disease.

Cytochrome P450IID6 recognized by LKM1 antibody is not exposed on the surface of hepatocytes.

PubMed Central

Yamamoto, A M; Mura, C; De Lemos-Chiarandini, C; Krishnamoorthy, R; Alvarez, F

1993-01-01

LKM1 autoantibody, directed against P450IID6, is accepted as a marker of a particular type of autoimmune hepatitis, but its role in the pathogenesis of the disease is controversial. Localization of P450IID6 on the cell surface of rat hepatocytes was previously reported, suggesting that membrane-bound P450IID6 could be the target of LKM1 antibodies, thus allowing immune lysis of hepatocytes. The objective of the present study was to determine, using various methods, the cell localization of P450IID6 in human and rat hepatocytes. Incubation of rat and human hepatocytes with LKM1-positive serum showed slight, if any, cell membrane staining using immunofluorescence, immunoperoxidase and immunoelectron microscopic studies. No staining of the plasma membrane of human hepatocytes was observed when incubations were carried out with immunoaffinity-purified antibody directed against peptide 254-271, the main epitope of P450IID6 recognized by all LKM1 sera tested. Chinese hamster ovary cells, transfected with the complete P450IID6 cDNA and incubated with the supernatant from a B cell lymphoblastoid cell line prepared with the lymphocytes of a LKM1-positive patient, did not show any staining of the cell surface by immunofluorescence. Incubation of rat microsomal fraction vesicles with LKM1-positive serum, followed by protein A-gold immunoelectron microscopy, displayed a staining of almost all vesicles, confirming that P450IID6 is present on the cytoplasmic side of the microsomal membrane, which makes it unable to be expressed on the cell surface even if it were transported from the endoplasmic reticulum (ER). Sulpho NHS Biotin labelling of rat hepatocyte cell membranes did not show the presence of a 50-kD molecule that could have reacted with LKM1 antibody. DNA sequencing of exon 1 of the CYP2D6 gene of a patient positive for LKM1 antibody did not show any difference from that of the normal published sequence of the gene. This does not favour an alteration of the NH2 terminal sequence of the P450IID6 molecule that could explain a translocation of the molecule to the luminal side of the ER, allowing its expression on the cell surface. These results indicate that, in all likelihood, P450IID6 molecule is not present on the cell surface of normal rat and human hepatocytes. Other mechanisms than antibody-mediated cell lysis directed against membrane P450IID6 antigenic determinants must be found to account for the destruction of hepatocytes observed in this disease. Images Fig. 2 Fig. 4 Fig. 5 Fig. 6 PMID:7685669

Immunolocalization of two hydrogenosomal enzymes of Trichomonas vaginalis.

PubMed

Brugerolle, G; Bricheux, G; Coffe, G

2000-01-01

Three monoclonal antibodies specific for malic enzyme and for the alpha- and beta-subunits, respectively, of the succinyl-coenzyme A (CoA) synthetase of Trichomonas vaginalis were used to immunolocalize these proteins in the cell. All antibodies labeled the hydrogenosome matrix as determined both by immunofluorescence and by immunogold staining. There was no labeling on the cell surface or in any other cell compartment. These results support the idea that these proteins are restricted to a hydrogenosomal function and do not play a role as adhesins at the plasma membrane surface.

Arrest of Nuclear Division in Plasmodium through Blockage of Erythrocyte Surface Exposed Ribosomal Protein P2

PubMed Central

Das, Sudipta; Basu, Himanish; Korde, Reshma; Tewari, Rita; Sharma, Shobhona

2012-01-01

Malaria parasites reside inside erythrocytes and the disease manifestations are linked to the growth inside infected erythrocytes (IE). The growth of the parasite is mostly confined to the trophozoite stage during which nuclear division occurs followed by the formation of cell bodies (schizogony). The mechanism and regulation of schizogony are poorly understood. Here we show a novel role for a Plasmodium falciparum 60S stalk ribosomal acidic protein P2 (PfP2) (PFC0400w), which gets exported to the IE surface for 6–8 hrs during early schizogony, starting around 26–28 hrs post-merozoite invasion. The surface exposure is demonstrated using multiple PfP2-specific monoclonal antibodies, and is confirmed through transfection using PfP2-GFP. The IE surface-exposed PfP2-protein occurs mainly as SDS-resistant P2-homo-tetramers. Treatment with anti-PfP2 monoclonals causes arrest of IEs at the first nuclear division. Upon removal of the antibodies, about 80–85% of synchronized parasites can be released even after 24 hrs of antibody treatment. It has been reported that a tubovesicular network (TVN) is set up in early trophozoites which is used for nutrient import. Anti-P2 monoclonal antibodies cause a complete fragmentation of TVN by 36 hrs, and impairs lipid import in IEs. These may be downstream causes for the cell-cycle arrest. Upon antibody removal, the TVN is reconstituted, and the cell division progresses. Each of the above properties is observed in the rodent malaria parasite species P. yoelii and P. berghei. The translocation of the P2 protein to the IE surface is therefore likely to be of fundamental importance in Plasmodium cell division. PMID:22912579

The architecture and biological function of dual antibody-coated dendrimers: enhanced control of circulating tumor cells and their hetero-adhesion to endothelial cells for metastasis prevention.

PubMed

Xie, Jingjing; Zhao, Rongli; Gu, Songen; Dong, Haiyan; Wang, Jichuang; Lu, Yusheng; Sinko, Patrick J; Yu, Ting; Xie, Fangwei; Wang, Lie; Shao, Jingwei; Jia, Lee

2014-01-01

Dissemination of circulating tumor cells (CTCs) in blood and their hetero-adhesion to vascular endothelial bed of distant metastatic secondary organs are the critical steps to initiate cancer metastasis. The rarity of CTCs made their in vivo capture technically challenging. Current techniques by virtue of nanostructured scaffolds monovalently conjugated with a single antibody and/or drug seem less efficient and specific in capturing CTCs. Here, we report a novel platform developed to re-engineer nanoscale dendrimers for capturing CTCs in blood and interfering their adhesion to vascular endothelial bed to form micrometastatic foci. The nanoscale dendrimers were spatiotemporally accommodated with dual antibodies to target two surface biomarkers of colorectal CTCs. Physiochemical characterization, including spectra, fluorescence, electron microscope, dynamic light scattering, electrophoresis, and chromatography analyses, was conducted to demonstrate the successful conjugation of dual antibodies to dendrimer surface. The dual antibody conjugates were able to specifically recognize and bind CTCs, moderately down-regulate the activity of the captured CTCs by arresting them in S phase. The related adhesion assay displayed that the dual antibody conjugates interfered the hetero-adhesion of CTCs to fibronectin (Fn)-coated substrates and human umbilical vein endothelial cells (HUVECs). The dual antibody conjugates also showed the enhanced specificity and efficiency in vitro and in vivo in restraining CTCs in comparison with their single antibody counterparts. The present study showed a novel means to effectively prevent cancer metastatic initiation by binding, restraining CTCs and inhibiting their hetero-adhesion to blood vessels, not by traditional cytotoxic-killing of cancer cells.

Antibody-Induced Internalization of the Human Respiratory Syncytial Virus Fusion Protein.

PubMed

Leemans, A; De Schryver, M; Van der Gucht, W; Heykers, A; Pintelon, I; Hotard, A L; Moore, M L; Melero, J A; McLellan, J S; Graham, B S; Broadbent, L; Power, U F; Caljon, G; Cos, P; Maes, L; Delputte, P

2017-07-15

Respiratory syncytial virus (RSV) infections remain a major cause of respiratory disease and hospitalizations among infants. Infection recurs frequently and establishes a weak and short-lived immunity. To date, RSV immunoprophylaxis and vaccine research is mainly focused on the RSV fusion (F) protein, but a vaccine remains elusive. The RSV F protein is a highly conserved surface glycoprotein and is the main target of neutralizing antibodies induced by natural infection. Here, we analyzed an internalization process of antigen-antibody complexes after binding of RSV-specific antibodies to RSV antigens expressed on the surface of infected cells. The RSV F protein and attachment (G) protein were found to be internalized in both infected and transfected cells after the addition of either RSV-specific polyclonal antibodies (PAbs) or RSV glycoprotein-specific monoclonal antibodies (MAbs), as determined by indirect immunofluorescence staining and flow-cytometric analysis. Internalization experiments with different cell lines, well-differentiated primary bronchial epithelial cells (WD-PBECs), and RSV isolates suggest that antibody internalization can be considered a general feature of RSV. More specifically for RSV F, the mechanism of internalization was shown to be clathrin dependent. All RSV F-targeted MAbs tested, regardless of their epitopes, induced internalization of RSV F. No differences could be observed between the different MAbs, indicating that RSV F internalization was epitope independent. Since this process can be either antiviral, by affecting virus assembly and production, or beneficial for the virus, by limiting the efficacy of antibodies and effector mechanism, further research is required to determine the extent to which this occurs in vivo and how this might impact RSV replication. IMPORTANCE Current research into the development of new immunoprophylaxis and vaccines is mainly focused on the RSV F protein since, among others, RSV F-specific antibodies are able to protect infants from severe disease, if administered prophylactically. However, antibody responses established after natural RSV infections are poorly protective against reinfection, and high levels of antibodies do not always correlate with protection. Therefore, RSV might be capable of interfering, at least partially, with antibody-induced neutralization. In this study, a process through which surface-expressed RSV F proteins are internalized after interaction with RSV-specific antibodies is described. One the one hand, this antigen-antibody complex internalization could result in an antiviral effect, since it may interfere with virus particle formation and virus production. On the other hand, this mechanism may also reduce the efficacy of antibody-mediated effector mechanisms toward infected cells. Copyright © 2017 American Society for Microbiology.

Antibody-Induced Internalization of the Human Respiratory Syncytial Virus Fusion Protein

PubMed Central

Leemans, A.; De Schryver, M.; Van der Gucht, W.; Heykers, A.; Pintelon, I.; Hotard, A. L.; Moore, M. L.; Melero, J. A.; McLellan, J. S.; Graham, B. S.; Broadbent, L.; Power, U. F.; Caljon, G.; Cos, P.; Maes, L.

2017-01-01

ABSTRACT Respiratory syncytial virus (RSV) infections remain a major cause of respiratory disease and hospitalizations among infants. Infection recurs frequently and establishes a weak and short-lived immunity. To date, RSV immunoprophylaxis and vaccine research is mainly focused on the RSV fusion (F) protein, but a vaccine remains elusive. The RSV F protein is a highly conserved surface glycoprotein and is the main target of neutralizing antibodies induced by natural infection. Here, we analyzed an internalization process of antigen-antibody complexes after binding of RSV-specific antibodies to RSV antigens expressed on the surface of infected cells. The RSV F protein and attachment (G) protein were found to be internalized in both infected and transfected cells after the addition of either RSV-specific polyclonal antibodies (PAbs) or RSV glycoprotein-specific monoclonal antibodies (MAbs), as determined by indirect immunofluorescence staining and flow-cytometric analysis. Internalization experiments with different cell lines, well-differentiated primary bronchial epithelial cells (WD-PBECs), and RSV isolates suggest that antibody internalization can be considered a general feature of RSV. More specifically for RSV F, the mechanism of internalization was shown to be clathrin dependent. All RSV F-targeted MAbs tested, regardless of their epitopes, induced internalization of RSV F. No differences could be observed between the different MAbs, indicating that RSV F internalization was epitope independent. Since this process can be either antiviral, by affecting virus assembly and production, or beneficial for the virus, by limiting the efficacy of antibodies and effector mechanism, further research is required to determine the extent to which this occurs in vivo and how this might impact RSV replication. IMPORTANCE Current research into the development of new immunoprophylaxis and vaccines is mainly focused on the RSV F protein since, among others, RSV F-specific antibodies are able to protect infants from severe disease, if administered prophylactically. However, antibody responses established after natural RSV infections are poorly protective against reinfection, and high levels of antibodies do not always correlate with protection. Therefore, RSV might be capable of interfering, at least partially, with antibody-induced neutralization. In this study, a process through which surface-expressed RSV F proteins are internalized after interaction with RSV-specific antibodies is described. One the one hand, this antigen-antibody complex internalization could result in an antiviral effect, since it may interfere with virus particle formation and virus production. On the other hand, this mechanism may also reduce the efficacy of antibody-mediated effector mechanisms toward infected cells. PMID:28468888

Evaluation of agglutination strength by a flow-induced cell movement assay based surface plasmon resonance (SPR) technique.

PubMed

Sudprasert, Krisda; Peungthum, Patjaree; Vongsakulyanon, Apirom; Amarit, Ratthasart; Somboonkaew, Armote; Sutapun, Boonsong; Kitpoka, Pimpun; Kunakorn, Mongkol; Srikhirin, Toemsak

2015-02-07

A flow-induced cell movement assay combined with a surface plasmon resonance (SPR) technique was developed to quantify the agglutination strength, derived from the standard tube-agglutination test. Red blood cells (RBCs), based on the ABO blood group system, were specifically captured by anti-A and/or anti-B antibodies immobilized on a sensor surface. The agglutination strength corresponds to the amount of antigen-antibody interactions or the strength of RBC adhesion. Under a shear flow, the adherent RBCs were forced to move out of the region of interest with different average cell velocities (vc) depending upon the adhesion strength and wall shear stress (WSS). That is, a higher adhesion strength (higher agglutination strength) or lower WSS represents a lower vc or vice versa. In this work, the agglutination strength was derived from the vc that was calculated from the time derivative of the relative SPR signal by using a simple model of cell movement response, whose validity was verified. The vc values of different samples were correlated with their agglutination strengths at a given WSS and antibody surface density. The vc decreased as the agglutination strength increased, which can be considered as a linear regression. The coefficient of variation of the calculated vc decreased to 0.1 as vc increased to 30 μm min(-1). The sensitivity of this assay can be controlled by optimizing the antibody surface density or the WSS. This assay has the capability to resolve the antigen density of A1 and B RBCs from that of A1B RBCs.

Surface functionalization of PLGA nanoparticles by non-covalent insertion of a homo-bifunctional spacer for active targeting in cancer therapy.

PubMed

Thamake, S I; Raut, S L; Ranjan, A P; Gryczynski, Z; Vishwanatha, J K

2011-01-21

This work reports the surface functionalization of polymeric PLGA nanoparticles by non-covalent insertion of a homo-bifunctional chemical crosslinker, bis(sulfosuccinimidyl) suberate (BS3) for targeted cancer therapy. We dissolved BS3 in aqueous solution of PVA during formulation of nanoparticles by a modified solid/oil/water emulsion solvent evaporation method. The non-covalent insertion of BS3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. Curcumin and annexin A2 were used as a model drug and a cell specific target, respectively. Nanoparticles were characterized for particle size, zeta potential and surface morphology. The qualitative assessment of antibody attachment was performed by transmission electron microscopy (TEM) as well as confocal microscopy. The optimized formulation showed antibody attachment of 86%. However, antibody attachment was abolished upon blocking the functional groups of BS3. The availability of functional antibodies was evaluated by the presence of a light chain fraction after gel electrophoresis. We further evaluated the in vitro release kinetics of curcumin from antibody coated and uncoated nanoparticles. The release of curcumin is enhanced upon antibody attachment and followed an anomalous release pattern. We also observed that the cellular uptake of nanoparticles was significantly higher in annexin A2 positive cells than in negative cells. Therefore, these results demonstrate the potential use of this method for functionalization as well as to deliver chemotherapeutic agents for treating cancer.

Surface functionalization of PLGA nanoparticles by non-covalent insertion of a homo-bifunctional spacer for active targeting in cancer therapy

NASA Astrophysics Data System (ADS)

Thamake, S. I.; Raut, S. L.; Ranjan, A. P.; Gryczynski, Z.; Vishwanatha, J. K.

2011-01-01

This work reports the surface functionalization of polymeric PLGA nanoparticles by non-covalent insertion of a homo-bifunctional chemical crosslinker, bis(sulfosuccinimidyl) suberate (BS3) for targeted cancer therapy. We dissolved BS3 in aqueous solution of PVA during formulation of nanoparticles by a modified solid/oil/water emulsion solvent evaporation method. The non-covalent insertion of BS3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. Curcumin and annexin A2 were used as a model drug and a cell specific target, respectively. Nanoparticles were characterized for particle size, zeta potential and surface morphology. The qualitative assessment of antibody attachment was performed by transmission electron microscopy (TEM) as well as confocal microscopy. The optimized formulation showed antibody attachment of 86%. However, antibody attachment was abolished upon blocking the functional groups of BS3. The availability of functional antibodies was evaluated by the presence of a light chain fraction after gel electrophoresis. We further evaluated the in vitro release kinetics of curcumin from antibody coated and uncoated nanoparticles. The release of curcumin is enhanced upon antibody attachment and followed an anomalous release pattern. We also observed that the cellular uptake of nanoparticles was significantly higher in annexin A2 positive cells than in negative cells. Therefore, these results demonstrate the potential use of this method for functionalization as well as to deliver chemotherapeutic agents for treating cancer.

Anti-cancer Activity of Novel TM4SF5-Targeting Antibodies through TM4SF5 Neutralization and Immune Cell-Mediated Cytotoxicity

PubMed Central

Ahn, Hye-Mi; Ryu, Jihye; Song, Jin Myeong; Lee, Yunhee; Kim, Hye-Jin; Ko, Dongjoon; Choi, Inpyo; Kim, Sang Jick; Lee, Jung Weon; Kim, Semi

2017-01-01

The transmembrane four L6 family member 5 (TM4SF5) protein is a novel molecular target for the prevention and treatment of hepatocellular carcinoma. TM4SF5 is highly expressed in liver, colon, esophageal, and pancreatic cancers and is implicated in tumor progression. Here, we screened monoclonal antibodies that specifically bound to the extracellular loop 2 (EC2) of TM4SF5 from a phage-displayed murine antibody (single-chain variable fragment; scFv) library. We constructed and characterized chimeric antibodies, Ab27 and Ab79, of scFv fused with Fc domain of human IgG1. The affinity (KD) of Ab27 and Ab79 for soluble EC2 was approximately 9.2 nM and 16.9 nM, respectively, as determined by surface plasmon resonance analysis. Ab27 and Ab79 efficiently bound to native TM4SF5 on the cell surface were internalized into the cancer cells, leading to a decrease in cell surface TM4SF5. Ab27 and Ab79 inhibited the proliferation and invasion of TM4SF5-positive liver and colon cancer cells and reduced FAK and c-Src phosphorylation. Ab27 and Ab79 also enhanced anoikis sensitivity and reduced survivin. Ab27 mediated antibody-dependent cell-mediated cytotoxicity in vitro. Ab27 and Ab79 efficiently inhibited tumor growth in a liver cancer xenograft model. These results strongly support the further development of Ab27 as a novel anti-cancer agent in the clinic. PMID:28255353

4F2 monoclonal antibody recognizes a surface antigen on spread human fibroblasts of embryonic but not of adult origin

PubMed Central

1984-01-01

The 4F2 monoclonal antibody (mAb) has been shown to recognize a 120- kilodalton glycoprotein expressed on the cell surface of human peripheral blood monocytes, activated (but not resting) T or B cells, and T and B lymphoblastoid cell lines. In this report we show that 4F2 mAb specifically binds to the surface of adherent human embryonic fibroblasts but fails to bind to normal adult fibroblasts. Moreover, 4F2 antigen was expressed on sarcoma-derived or SV40-transformed adult fibroblastic cells. Finally, addition of 4F2 mAb inhibited the growth of cultured HT-1080 fibrosarcoma cell line, but had no inhibitory effect on various embryonic and adult normal or transformed fibroblasts. PMID:6538202

Method of making a membrane having hydrophilic and hydrophobic surfaces for adhering cells or antibodies by using atomic oxygen or hydroxyl radicals

NASA Technical Reports Server (NTRS)

Koontz, Steven L. (Inventor); Spaulding, Glenn F. (Inventor)

1994-01-01

A portion of an organic polymer article such as a membrane is made hydrophilic by exposing a hydrophobic surface of the article to a depth of about 50 to about 5000 angstroms to atomic oxygen or hydroxyl radicals at a temperature below 100C., preferably below 40 C, to form a hydrophilic uniform surface layer of hydrophilic hydroxyl groups. The atomic oxygen and hydroxyl radicals are generated by a flowing afterglow microwave discharge, and the surface is outside of a plasma produced by the discharge. A membrane having both hydrophilic and hydrophobic surfaces can be used in an immunoassay by adhering antibodies to the hydrophobic surface. In another embodiment, the membrane is used in cell culturing where cells adhere to the hydrophilic surface. Prior to adhering cells, the hydrophilic surface may be grafted with a compatibilizing compound. A plurality of hydrophilic regions bounded by adjacent hydrophobic regions can be produced such that a maximum of one cell per each hydrophilic region adheres.

Heterophilic binding of the adhesion molecules poliovirus receptor and immunoglobulin superfamily 4A in the interaction between mouse spermatogenic and Sertoli cells.

PubMed

Wakayama, Tomohiko; Sai, Yoshimichi; Ito, Akihiko; Kato, Yukio; Kurobo, Miho; Murakami, Yoshinori; Nakashima, Emi; Tsuji, Akira; Kitamura, Yukihiko; Iseki, Shoichi

2007-06-01

The cell adhesion protein immunoglobulin superfamily 4A (IGSF4A) is expressed on the surfaces of spermatogenic cells in the mouse testis. During spermatogenesis, IGSF4A is considered to bind to the surface of Sertoli cells in a heterophilic manner. To identify this unknown partner of IGSF4A, we generated rat monoclonal antibodies against the membrane proteins of mouse Sertoli cells grown in primary culture. Using these monoclonal antibodies, we isolated a clone that immunostained Sertoli cells and reacted with the product of immunoprecipitation of the homogenate of mouse testis with anti-IGSF4A antibody. Subsequently, to identify the Sertoli cell membrane protein that is recognized by this monoclonal antibody, we performed expression cloning of a cDNA library from the mouse testis. As a result, we identified poliovirus receptor (PVR), which is another IGSF-type cell adhesion molecule, as the binding partner of IGSF4A. The antibodies raised against PVR and IGSF4A immunoprecipitated both antigens in the homogenate of mouse testis. Immunoreactivity for PVR was present in Sertoli cells but not in spermatogenic cells at all stages of spermatogenesis. Overexpression of PVR in TM4, a mouse Sertoli cell line, increased more than three-fold its capacity to adhere to Tera-2, which is a human cell line that expresses IGSF4A. These findings suggest that the heterophilic binding of PVR to IGSF4A is responsible, at least in part, for the interaction between Sertoli and spermatogenic cells during mouse spermatogenesis.

Gluten-specific antibodies of celiac disease gut plasma cells recognize long proteolytic fragments that typically harbor T-cell epitopes.

PubMed

Dørum, Siri; Steinsbø, Øyvind; Bergseng, Elin; Arntzen, Magnus Ø; de Souza, Gustavo A; Sollid, Ludvig M

2016-05-05

This study aimed to identify proteolytic fragments of gluten proteins recognized by recombinant IgG1 monoclonal antibodies generated from single IgA plasma cells of celiac disease lesions. Peptides bound by monoclonal antibodies in complex gut-enzyme digests of gluten treated with the deamidating enzyme transglutaminase 2, were identified by mass spectrometry after antibody pull-down with protein G beads. The antibody bound peptides were long deamidated peptide fragments that contained the substrate recognition sequence of transglutaminase 2. Characteristically, the fragments contained epitopes with the sequence QPEQPFP and variants thereof in multiple copies, and they typically also harbored many different gluten T-cell epitopes. In the pull-down setting where antibodies were immobilized on a solid phase, peptide fragments with multivalent display of epitopes were targeted. This scenario resembles the situation of the B-cell receptor on the surface of B cells. Conceivably, B cells of celiac disease patients select gluten epitopes that are repeated multiple times in long peptide fragments generated by gut digestive enzymes. As the fragments also contain many different T-cell epitopes, this will lead to generation of strong antibody responses by effective presentation of several distinct T-cell epitopes and establishment of T-cell help to B cells.

Gluten-specific antibodies of celiac disease gut plasma cells recognize long proteolytic fragments that typically harbor T-cell epitopes

PubMed Central

Dørum, Siri; Steinsbø, Øyvind; Bergseng, Elin; Arntzen, Magnus Ø.; de Souza, Gustavo A.; Sollid, Ludvig M.

2016-01-01

This study aimed to identify proteolytic fragments of gluten proteins recognized by recombinant IgG1 monoclonal antibodies generated from single IgA plasma cells of celiac disease lesions. Peptides bound by monoclonal antibodies in complex gut-enzyme digests of gluten treated with the deamidating enzyme transglutaminase 2, were identified by mass spectrometry after antibody pull-down with protein G beads. The antibody bound peptides were long deamidated peptide fragments that contained the substrate recognition sequence of transglutaminase 2. Characteristically, the fragments contained epitopes with the sequence QPEQPFP and variants thereof in multiple copies, and they typically also harbored many different gluten T-cell epitopes. In the pull-down setting where antibodies were immobilized on a solid phase, peptide fragments with multivalent display of epitopes were targeted. This scenario resembles the situation of the B-cell receptor on the surface of B cells. Conceivably, B cells of celiac disease patients select gluten epitopes that are repeated multiple times in long peptide fragments generated by gut digestive enzymes. As the fragments also contain many different T-cell epitopes, this will lead to generation of strong antibody responses by effective presentation of several distinct T-cell epitopes and establishment of T-cell help to B cells. PMID:27146306

iPS-cell derived dendritic cells and macrophages for cancer therapy.

PubMed

Senju, Satoru

2016-08-01

Antibody-based anti-cancer immunotherapy was recently recognized as one of the truly effective therapies for cancer patients. Antibodies against cell surface cancer antigens, such as CD20, and also those against immune-inhibitory molecules called "immune checkpoint blockers", such as CTLA4 or PD1, have emerged. Large-scale clinical trials have confirmed that, in some cases, antibody-based drugs are superior to conventional chemotherapeutic agents. These antibody-based drugs are now being manufactured employing a mass-production system by pharmaceutical companies. Anti-cancer therapy by immune cells, i.e. cell-based immunotherapy, is expected to be more effective than antibody therapy, because immune cells can recognize, infiltrate, and act in cancer tissues more directly than antibodies. In order to achieve cell-based anti-cancer immunotherapy, it is necessary to develop manufacturing systems for mass-production of immune cells. Our group has been studying immunotherapy with myeloid cells derived from ES cells or iPS cells. These pluripotent stem cells can be readily propagated under constant culture conditions, with expansion into a large quantity. We consider these stem cells to be the most suitable cellular source for mass-production of immune cells. This review introduces our studies on anti-cancer therapy with iPS cell-derived dendritic cells and iPS cell-derived macrophages.

Redirecting T cells to eradicate B-cell acute lymphoblastic leukemia: bispecific T-cell engagers and chimeric antigen receptors.

PubMed

Aldoss, I; Bargou, R C; Nagorsen, D; Friberg, G R; Baeuerle, P A; Forman, S J

2017-04-01

Recent advances in antibody technology to harness T cells for cancer immunotherapy, particularly in the difficult-to-treat setting of relapsed/refractory acute lymphoblastic leukemia (r/r ALL), have led to innovative methods for directing cytotoxic T cells to specific surface antigens on cancer cells. One approach involves administration of soluble bispecific (or dual-affinity) antibody-based constructs that temporarily bridge T cells and cancer cells. Another approach infuses ex vivo-engineered T cells that express a surface plasma membrane-inserted antibody construct called a chimeric antigen receptor (CAR). Both bispecific antibodies and CARs circumvent natural target cell recognition by creating a physical connection between cytotoxic T cells and target cancer cells to activate a cytolysis signaling pathway; this connection allows essentially all cytotoxic T cells in a patient to be engaged because typical tumor cell resistance mechanisms (such as T-cell receptor specificity, antigen processing and presentation, and major histocompatibility complex context) are bypassed. Both the bispecific T-cell engager (BiTE) antibody construct blinatumomab and CD19-CARs are immunotherapies that have yielded encouraging remission rates in CD19-positive r/r ALL, suggesting that they might serve as definitive treatments or bridging therapies to allogeneic hematopoietic cell transplantation. With the introduction of these immunotherapies, new challenges arise related to unique toxicities and distinctive pathways of resistance. An increasing body of knowledge is being accumulated on how to predict, prevent, and manage such toxicities, which will help to better stratify patient risk and tailor treatments to minimize severe adverse events. A deeper understanding of the precise mechanisms of action and immune resistance, interaction with other novel agents in potential combinations, and optimization in the manufacturing process will help to advance immunotherapy outcomes in the r/r ALL setting.

Comparison between immunofluorescence and immunomagnetic techniques of cytometry

NASA Astrophysics Data System (ADS)

Tchikov, V.; Schütze, S.; Krönke, M.

1999-04-01

Magnetophoresis and fluorescence activated cell sorting were used for evaluation of immunochemical properties of magnetic particles and fluorescent probes. The HLA-Bw6 antigen on surfaces of REH cells was detected with a primary monoclonal antibody and a secondary antibody coupled with fluorescent molecules or magnetic particles. Magnetophoresis can find applications in biology and medicine for measuring percentages of cell subpopulations.

Shape recognition of microbial cells by colloidal cell imprints

NASA Astrophysics Data System (ADS)

Borovička, Josef; Stoyanov, Simeon D.; Paunov, Vesselin N.

2013-08-01

We have engineered a class of colloids which can recognize the shape and size of targeted microbial cells and selectively bind to their surfaces. These imprinted colloid particles, which we called ``colloid antibodies'', were fabricated by partial fragmentation of silica shells obtained by templating the targeted microbial cells. We successfully demonstrated the shape and size recognition between such colloidal imprints and matching microbial cells. High percentage of binding events of colloidal imprints with the size matching target particles was achieved. We demonstrated selective binding of colloidal imprints to target microbial cells in a binary mixture of cells of different shapes and sizes, which also resulted in high binding selectivity. We explored the role of the electrostatic interactions between the target cells and their colloid imprints by pre-coating both of them with polyelectrolytes. Selective binding occurred predominantly in the case of opposite surface charges of the colloid cell imprint and the targeted cells. The mechanism of the recognition is based on the amplification of the surface adhesion in the case of shape and size match due to the increased contact area between the target cell and the colloidal imprint. We also tested the selective binding for colloid imprints of particles of fixed shape and varying sizes. The concept of cell recognition by colloid imprints could be used for development of colloid antibodies for shape-selective binding of microbes. Such colloid antibodies could be additionally functionalized with surface groups to enhance their binding efficiency to cells of specific shape and deliver a drug payload directly to their surface or allow them to be manipulated using external fields. They could benefit the pharmaceutical industry in developing selective antimicrobial therapies and formulations.

Heat shock 70-kDa protein 8 isoform 1 is expressed on the surface of human embryonic stem cells and downregulated upon differentiation.

PubMed

Son, Yeon Sung; Park, Jae Hyun; Kang, Young Kook; Park, Jin-Sung; Choi, Hong Seo; Lim, Ji Young; Lee, Jeoung Eun; Lee, Jung Bok; Ko, Myoung Seok; Kim, Yong-Sam; Ko, Jeong-Heon; Yoon, Hyun Soo; Lee, Kwang-Woong; Seong, Rho Hyun; Moon, Shin Yong; Ryu, Chun Jeih; Hong, Hyo Jeong

2005-01-01

The cell-surface markers used routinely to define the undifferentiated state and pluripotency of human embryonic stem cells (hESCs) are those used in mouse embryonic stem cells (mESCs) because of a lack of markers directly originated from hESC itself. To identify more hESC-specific cell-surface markers, we generated a panel of monoclonal antibodies (MAbs) by immunizing the irradiated cell clumps of hESC line Miz-hES1, and selected 26 MAbs that were able to bind to Miz-hES1 cells but not to mESCs, mouse embryonic fibroblast cells, and STO cells. Most antibodies did not bind to human neural progenitor cells derived from the Miz-hES1 cells, either. Of these, MAb 20-202S (IgG1, kappa) immunoprecipitated a cell-surface protein of 72-kDa from the lysate of biotin-labeled Miz-hES1 cells, which was identified to be heat shock 70-kDa protein 8 isoform 1 (HSPA8) by quadrupole time-of-flight tandem mass spectrometry. Immunocytochemical analyses proved that the HSPA8 protein was also present on the surface of hESC lines Miz-hES4, Miz-hES6, and HSF6. Two-color flow cytometric analysis of Miz-hES1 and HSF6 showed the coexpression of the HSPA8 protein with other hESC markers such as stage-specific embryonic antigen 3 (SSEA3), SSEA4, TRA-1-60, and TRA-1-81. Flow cytometric and Western blot analyses using various cells showed that MAb 20-202S specifically bound to the HSPA8 protein on the surface of Miz-hES1, contrary to other anti-HSP70 antibodies examined. Furthermore, the surface expression of the HSPA8 protein on Miz-hES1 was markedly downregulated upon differentiation. These data indicate that a novel MAb 20-202S recognizes the HSPA8 protein on the surface of hESCs and suggest that the HSPA8 protein is a putative cell-surface marker for undifferentiated hESCs.

Standing out from the crowd: How to identify plasma cells.

PubMed

Tellier, Julie; Nutt, Stephen L

2017-08-01

Being the sole source of antibody, plasmablasts and plasma cells are essential for protective immunity. Due to their relative rarity, heterogeneity and the loss of many canonical B-cell markers, antibody-secreting cells (ASCs) have often been problematic to identify and further characterize. In the mouse, the combination of the expression of CD138 and BLIMP-1, has led to many insights into ASC biology, although this approach requires the use of a GFP reporter strain. In the current issue of the European Journal of Immunology, two independent studies by Wilmore et al. and Pracht et al. provide alternative approaches to identify all murine ASCs using antibodies against the cell surface proteins, Sca-1 and TACI, respectively. Here we will discuss the advantages of these new approaches to identify ASCs in the context of our emerging knowledge of the cell surface phenotype and gene expression program of various ASC subsets in the murine and human systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New markers for tracking endoderm induction and hepatocyte differentiation from human pluripotent stem cells

PubMed Central

Holtzinger, Audrey; Streeter, Philip R.; Sarangi, Farida; Hillborn, Scott; Niapour, Maryam; Ogawa, Shinichiro; Keller, Gordon

2015-01-01

The efficient generation of hepatocytes from human pluripotent stem cells (hPSCs) requires the induction of a proper endoderm population, broadly characterized by the expression of the cell surface marker CXCR4. Strategies to identify and isolate endoderm subpopulations predisposed to the liver fate do not exist. In this study, we generated mouse monoclonal antibodies against human embryonic stem cell-derived definitive endoderm with the goal of identifying cell surface markers that can be used to track the development of this germ layer and its specification to a hepatic fate. Through this approach, we identified two endoderm-specific antibodies, HDE1 and HDE2, which stain different stages of endoderm development and distinct derivative cell types. HDE1 marks a definitive endoderm population with high hepatic potential, whereas staining of HDE2 tracks with developing hepatocyte progenitors and hepatocytes. When used in combination, the staining patterns of these antibodies enable one to optimize endoderm induction and hepatic specification from any hPSC line. PMID:26493401

The level of HER2 expression is a predictor of antibody-HER2 trafficking behavior in cancer cells

PubMed Central

Ram, Sripad; Kim, Dongyoung; Ober, Raimund J; Ward, E Sally

2014-01-01

The receptor tyrosine kinase HER2 is known to play a central role in mitogenic signaling, motivating the development of targeted, HER2-specific therapies. However, despite the longstanding use of antibodies to target HER2, controversies remain concerning antibody/HER2 trafficking behavior in cancer cells. Understanding this behavior has direct relevance to the mechanism of action and effective design of such antibodies. In the current study, we analyzed the intracellular dynamics of trastuzumab, a marketed HER2-targeting antibody, in a panel of breast and prostate cancer cell lines that have a wide range of HER2 expression levels. Our results reveal distinct post-endocytic trafficking behavior of antibody-HER2 complexes in cells with different HER2 expression levels. In particular, HER2-overexpressing cells exhibit efficient HER2 recycling and limited reductions in HER2 levels upon antibody treatment, and consequently display a high level of antibody persistence on their plasma membrane. By contrast, in cells with low HER2 expression, trastuzumab treatment results in rapid antibody clearance from the plasma membrane combined with substantial decreases in HER2 levels and undetectable levels of recycling. A cell line with intermediate levels of HER2 expression exhibits both antibody recycling and clearance from the cell surface. Significantly, these analyses demonstrate that HER2 expression levels, rather than cell origin (breast or prostate), is a determinant of subcellular trafficking properties. Such studies have relevance to optimizing the design of antibodies to target HER2. PMID:25517306

[Screening serum response special antibodies of U251 cell line from surface display phage antibody library].

PubMed

Yu, Min; Tan, De-Yong; Qian, Wei; Lai, Jian-Hua; Sun, Gui-Lin

2004-05-01

U251 cell is a sensitive cell line to serum, which stops at G0 phase of cell cycle in no-serum medium, and recovers growth when the serum is added into no-serum medium. The cell can express corresponding proteins in different phase of cell cycle. Therefore it is very signification for the study of cell cycle regulation mechanism that explores these proteins. In this paper, the mouse antibody phage display library was added into the bottle in which the serum starvation U251 cells had been cultured, and the special antibody phages were absorbed. Then the absorbed antibody phages were amplified by adding E. coli TG1 and helper phage M13K07. Amplified antibody phages were added into bottle in which the serum cultured cell after serum starvation (follow named as serum recovered cells) were incubated, so that the cell absorbed the no-special antibody phages for the serum starvation cell and the special antibody phages were in supernatant. The remaining no-special antibody phages in the supernatant were discarded by repeating above program 3-4 times. The pure special antibody phages were gotten, and amplified by adding the host cell E. coli TG1 and helper phage M13K07. Then the host bacterium infected special antibody phage was spread on the plate medium with ampicillin, and the monoclonal antibody phages were gotten. Using same as above program, the monoclonal antibody phages absorbed specially for serum recovered U251 cells were obtained when the serum recovered cells instead of serum starvation cells and serum starvation cells instead of serum recovered cells. In this study, ninety-six positive monoclonal antibody phages that absorbed specially the serum starvation cells and eighty-two positive monoclonal antibody phages that absorbed specially the serum recovered cells were obtained. By using cell immunochemistry assay, two special signification antibodies were obtained. one (No.11) was the strong response in serum starvation cells, the other (No.2) was the strong response in serum recovered cells. The antibody No.2 had the distinctive response to the serum recovered cells in different incubation time (15min, 30min, 1h, 2h, 4h, 8h, 12h and 48h) after serum starvation. The results showed that No.2 antibody would be useful to research the factors of cell cycle regulation and apply to tumor diagnosis.

Envelope-specific antibodies and antibody-derived molecules for treating and curing HIV infection

PubMed Central

Ferrari, Guido; Haynes, Barton F.; Koenig, Scott; Nordstrom, Jeffrey L.; Margolis, David M.; Tomaras, Georgia D.

2017-01-01

HIV-1 is a retrovirus that integrates into host chromatin and can remain transcriptionally quiescent in a pool of immune cells. This characteristic enables HIV-1 to evade both host immune responses and antiretroviral drugs, leading to persistent infection. Upon reactivation of proviral gene expression, HIV-1 envelope (HIV-1 Env) glycoproteins are expressed on the cell surface, transforming latently infected cells into targets for HIV-1 Env-specific monoclonal antibodies (mAbs), which can engage immune effector cells to kill productively infected CD4+ T cells and thus limit the spread of progeny virus. Recent innovations in antibody engineering have resulted in novel immunotherapeutics such as bispecific dual-affinity re-targeting (DART) molecules and other bi- and trispecific antibody designs that can recognize HIV-1 Env and recruit cytotoxic effector cells to kill CD4+ T cells latently infected with HIV‑1. Here, we review these immunotherapies, which are designed with the goal of curing HIV-1 infection. PMID:27725635

Coengagement of CD16 and CD94 receptors mediates secretion of chemokines and induces apoptotic death of naive natural killer cells.

PubMed

Jewett, Anahid; Cacalano, Nicholas A; Head, Christian; Teruel, Antonia

2006-04-01

Down-modulation of CD16 (FcgammaRIII) receptors and loss of natural killer (NK) cell function have been observed in oral cancer patients. However, neither the mechanisms nor the significance of the decrease in CD16 receptors have been fully understood. The cytotoxic activity and survival of NK cells are negatively regulated by antibodies directed against CD16 surface receptor. The addition of anti-CD94 antibody in combination with either F(ab')(2) fragment or intact anti-CD16 antibody to NK cells resulted in significant inhibition of NK cell cytotoxic function and induction of apoptosis in resting human peripheral blood NK cells. Addition of interleukin-2 to anti-CD16 and/or anti-CD94 antibody-treated NK cells significantly inhibited apoptosis and increased the function of NK cells. There was a significant increase in tumor necrosis factor-alpha (TNF-alpha) but not IFN-gamma secretion in NK cells treated either with anti-CD16 antibody alone or in combination with anti-CD94 antibodies. Consequently, the addition of anti-TNF-alpha antibody partially inhibited apoptosis of NK cells mediated by the combination of anti-CD94 and anti-CD16 antibodies. Increase in apoptotic death of NK cells also correlated with an increase in type 2 inflammatory cytokines and in the induction of chemokines. Thus, we conclude that binding of antibodies to CD16 and CD94 NK cell receptors induces death of the NK cells and signals for the release of chemokines.

Anti-CD22 and anti-CD79b antibody-drug conjugates preferentially target proliferating B cells.

PubMed

Fuh, Franklin K; Looney, Caroline; Li, Dongwei; Poon, Kirsten A; Dere, Randall C; Danilenko, Dimitry M; McBride, Jacqueline; Reed, Chae; Chung, Shan; Zheng, Bing; Mathews, William Rodney; Polson, Andrew; Prabhu, Saileta; Williams, Marna

2017-04-01

CD22 and CD79b are cell-surface receptors expressed on B-cell-derived malignancies such as non-Hodgkin's lymphoma (NHL). An anti-mitotic agent, monomethyl auristatin E, was conjugated to anti-CD22 and anti-CD79b antibodies to develop target-specific therapies for NHL. The mechanism of action (MOA) and pharmacological and pharmacokinetic (PK) profiles of these antibody-drug conjugates (ADCs) were investigated in cynomolgus monkeys. Animals were administered anti-CD22 or anti-CD79b ADCs, respective unconjugated antibodies or vehicle. Pharmacodynamic effects on total and proliferating B cells and serum PK were then assessed. Antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) of the ADCs were evaluated in vitro. Depletion of B cells was observed after administration of either ADC or the respective unconjugated antibodies. An extended duration of depletion was observed in animals administered ADCs. Similarly, preferential depletion of proliferating B cells in blood and germinal centre B cells in spleen were only observed in animals administered ADCs. Serum PK profiles of ADCs and respective unconjugated antibodies were comparable. In vitro, anti-human CD22 and anti-human CD79b antibodies showed no or only moderate ADCC activity, respectively; neither antibody had CDC activity. The findings support the proposed MOA: initial depletion of total B cells by antibody-mediated opsonization, followed by preferential, sustained depletion of proliferating B cells by the auristatin conjugate due to its anti-mitotic action. Delivering potent anti-mitotic agents to B cells via the specificity of monoclonal antibodies provides a means to eliminate pathogenic B cells in NHL with improved risk-benefit profiles over traditional chemotherapeutics. © 2016 Genentech. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.

DropArray™, a wall-less 96-well plate for uptake and immunofluorescence microscopy, confirms CD22 recycles.

PubMed

Ingle, Gladys S; Scales, Suzie J

2014-03-01

CD22 is a cell surface glycoprotein restricted to normal and malignant B-cells and is the target of several anti-CD22 antibody-based cancer therapies. For therapeutic antibody-payload conjugates, it is important to understand the subcellular trafficking of anti-CD22 antibodies to optimize antibody and/or linker-drug properties to maximize antitumor efficacy. It is agreed that anti-CD22 antibodies rapidly internalize, but controversial whether they recycle or are degraded in lysosomes, and it is unclear if trafficking is antibody or cell-type dependent. No studies examined anti-CD22 trafficking to either pathway in B-cells over time by dual immunofluorescence microscopy, likely partly because multiple samples of suspension cells are tedious to stain. We overcame this by using DropArray™, a novel wall-less 96-well plate technology allowing rapid simultaneous staining of suspension or adherent cells in small (10-20 μL) volumes. We examined the time-course of trafficking of five different anti-CD22 antibodies in eight B-cell lines representing four B-cell cancer types and show that in all cases antibodies internalize within 5 min and recycle, with only small amounts eventually trafficking to lysosomes. CD22 also localizes to recycling endosomes at steady state in the absence of antibody. Our data may help explain the differential efficacies of anti-CD22 antibodies conjugated to different therapeutic payloads. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Conservation of myeloid surface antigens on primate granulocytes.

PubMed

Letvin, N L; Todd, R F; Palley, L S; Schlossman, S F; Griffin, J D

1983-02-01

Monoclonal antibodies reactive with myeloid cell surface antigens were used to study evolutionary changes in granulocyte surface antigens from primate species. Certain of these granulocyte membrane antigens are conserved in phylogenetically distant species, indicating the potential functional importance of these structures. The degree of conservation of these antigens reflects the phylogenetic relationship between primate species. Furthermore, species of the same genus show similar patterns of binding to this panel of anti-human myeloid antibodies. This finding of conserved granulocyte surface antigens suggests that non-human primates may provide a model system for exploring uses of monoclonal antibodies in the treatment of human myeloid disorders.

Minimizing antibody surface density on liposomes while sustaining cytokine-activated EC targeting.

PubMed

Almeda, Dariela; Wang, Biran; Auguste, Debra T

2015-02-01

Liposomes may be engineered to target inflamed endothelium by mimicking ligand-receptor interactions between leukocytes and cytokine-activated endothelial cells (ECs). The upregulation and assembly of vascular cell adhesion molecule-1 (VCAM1) and E-selectin on the cell membrane upon exposure to cytokines have shown potential for drug delivery vehicles to target sites of chronic endothelial inflammation, such as atherosclerosis and cancer. Herein, we characterized EC surfaces by measuring the E-selectin and VCAM1 surface densities and adhesion forces of aVCAM1 and aE-selectin to ECs. We quantified the antibody density, ratio, and diffusivity of liposomes to achieve significant binding and internalization. At 1 h, the 1:1 ratio of VCAM1:E-selectin antibodies was significantly higher than 1:0 and 0:1. Significant binding and uptake was achieved at aE-selectin densities as low as 400 molecules/μm(2). The highest levels of binding and uptake were achieved when using a 1:1 ratio of VCAM1:E-selectin antibodies at a density of 1000 molecules/μm(2); this density is 85% lower than previous reports. The binding and uptake of functionalized liposomes were reduced to levels comparable to IgG functionalized liposomes upon a 10-fold reduction in liposome membrane diffusivity. We conclude with a liposomal design that discriminates between healthy and inflamed endothelium while reducing antibody surface presentation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparison of Antibody-Dependent Cell-Mediated Cytotoxicity and Virus Neutralization by HIV-1 Env-Specific Monoclonal Antibodies

PubMed Central

von Bredow, Benjamin; Arias, Juan F.; Heyer, Lisa N.; Moldt, Brian; Le, Khoa; Robinson, James E.; Burton, Dennis R.

2016-01-01

ABSTRACT Although antibodies to the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein have been studied extensively for their ability to block viral infectivity, little data are currently available on nonneutralizing functions of these antibodies, such as their ability to eliminate virus-infected cells by antibody-dependent cell-mediated cytotoxicity (ADCC). HIV-1 Env-specific antibodies of diverse specificities, including potent broadly neutralizing and nonneutralizing antibodies, were therefore tested for ADCC against cells infected with a lab-adapted HIV-1 isolate (HIV-1NL4-3), a primary HIV-1 isolate (HIV-1JR-FL), and a simian-human immunodeficiency virus (SHIV) adapted for pathogenic infection of rhesus macaques (SHIVAD8-EO). In accordance with the sensitivity of these viruses to neutralization, HIV-1NL4-3-infected cells were considerably more sensitive to ADCC, both in terms of the number of antibodies and magnitude of responses, than cells infected with HIV-1JR-FL or SHIVAD8-EO. ADCC activity generally correlated with antibody binding to Env on the surfaces of virus-infected cells and with viral neutralization; however, neutralization was not always predictive of ADCC, as instances of ADCC in the absence of detectable neutralization, and vice versa, were observed. These results reveal incomplete overlap in the specificities of antibodies that mediate these antiviral activities and provide insights into the relationship between ADCC and neutralization important for the development of antibody-based vaccines and therapies for combating HIV-1 infection. IMPORTANCE This study provides fundamental insights into the relationship between antibody-dependent cell-mediated cytotoxicity (ADCC) and virus neutralization that may help to guide the development of antibody-based vaccines and immunotherapies for the prevention and treatment of HIV-1 infection. PMID:27122574

Comparison of Antibody-Dependent Cell-Mediated Cytotoxicity and Virus Neutralization by HIV-1 Env-Specific Monoclonal Antibodies.

PubMed

von Bredow, Benjamin; Arias, Juan F; Heyer, Lisa N; Moldt, Brian; Le, Khoa; Robinson, James E; Zolla-Pazner, Susan; Burton, Dennis R; Evans, David T

2016-07-01

Although antibodies to the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein have been studied extensively for their ability to block viral infectivity, little data are currently available on nonneutralizing functions of these antibodies, such as their ability to eliminate virus-infected cells by antibody-dependent cell-mediated cytotoxicity (ADCC). HIV-1 Env-specific antibodies of diverse specificities, including potent broadly neutralizing and nonneutralizing antibodies, were therefore tested for ADCC against cells infected with a lab-adapted HIV-1 isolate (HIV-1NL4-3), a primary HIV-1 isolate (HIV-1JR-FL), and a simian-human immunodeficiency virus (SHIV) adapted for pathogenic infection of rhesus macaques (SHIVAD8-EO). In accordance with the sensitivity of these viruses to neutralization, HIV-1NL4-3-infected cells were considerably more sensitive to ADCC, both in terms of the number of antibodies and magnitude of responses, than cells infected with HIV-1JR-FL or SHIVAD8-EO ADCC activity generally correlated with antibody binding to Env on the surfaces of virus-infected cells and with viral neutralization; however, neutralization was not always predictive of ADCC, as instances of ADCC in the absence of detectable neutralization, and vice versa, were observed. These results reveal incomplete overlap in the specificities of antibodies that mediate these antiviral activities and provide insights into the relationship between ADCC and neutralization important for the development of antibody-based vaccines and therapies for combating HIV-1 infection. This study provides fundamental insights into the relationship between antibody-dependent cell-mediated cytotoxicity (ADCC) and virus neutralization that may help to guide the development of antibody-based vaccines and immunotherapies for the prevention and treatment of HIV-1 infection. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

[Targeted detecting HER2 expression with recombinant anti HER2 ScFv-GFP fusion antibody].

PubMed

Gao, Guohui; Chen, Chong; Yang, Yanmei; Yang, Han; Wang, Jindan; Zheng, Yi; Huang, Qidi; Hu, Xiaoqu

2012-08-01

To verify the reliability of targeted detecting HER2 positive cancer cells and clinical pathological tissue specimens with a recombinant anti HER2 single chain antibody in single chain Fv fragment (scFv) format, we have constructed the fusion variable regions of the ScFv specific for HER2/neu. labeled a green-fluorescent protein(GFP). The humanized recombinant Anti HER2 ScFv-GFP gene was inserted into pFast Bac HT A, and expressed in insect cells sf9. Then the recombinant fusion protein Anti HER2 ScFv-GFP was properly purified with Ni2+-NTA affinity chromatography from the infected sf9 cells used to test the specificity of the fusion antibody for HER2 positive cancer cells. Firstly, the purified antibody incubated with HER2 positive breast cancer cells SKBR3, BT474 and HER2 negative breast cancer cells MCF7 for 12 h/24 h/48 h at 37 degrees C, in order to confirm targeted detecting HER2 positive breast cancer cells by Laser Confocal Microscopy. Furthermore, the same clinical pathological tissue samples were assessed by immunohistochemistry (IHC) and the fusion antibody Anti HER2 ScFv-GFP in the meanwhile. The data obtained indicated that the recombinant eukaryotic expression plasmid pFast Bac HT A/Anti HER2 ScFv-GFP was constructed successfully In addition, obvious green fluorescent was observed in insect cells sf9. When the purified fusion antibody was incubated with different cancer cells, much more green fluorescent was observed on the surface of the HER2 positive cancer cells SKBR3 and BT474. In contrast, no green fluorescent on the surface of the HER2 negative cancer cells MCF7 was detected. The concentration of the purified fusion antibody was 115.5 microg/mL, of which protein relative molecular weight was 60 kDa. The analysis showed the purity was about 97% and the titer was about 1:64. The detection results of IHC and fusion antibody testing indicated the conformity. In summary, the study showed that the new fusion antibody Anti HER2 ScFv-GFP can test HER2 positive cancer cells, indicating a potential candidate method for clinical HER2 positive specimens detection.

Pneumococcal surface protein A (PspA) is effective at eliciting T cell-mediated responses during invasive pneumococcal disease in adults

PubMed Central

Baril, L; Dietemann, J; Essevaz-Roulet, M; Béniguel, L; Coan, P; Briles, D E; Guy, B; Cozon, G

2006-01-01

Humoral immune response is essential for protection against invasive pneumococcal disease and this property is the basis of the polysaccharide-based anti-pneumococcal vaccines. Pneumococcal surface protein A (PspA), a cell-wall-associated surface protein, is a promising component for the next generation of pneumococcal vaccines. This PspA antigen has been shown to stimulate an antibody-based immunity. In the present study, we evaluated the capacity of PspA to stimulate CD4+ T cells which are needed for the correct development of a B cell based immune response in humans. Cellular immunity to PspA was evaluated by whole-blood culture with different pneumococcal antigens, followed by flow cytometric detection of activated CD4+CD25+ T cells. T cell-mediated immune responses to recombinant PspA proteins were assessed in acute-phase and convalescent blood from adults with invasive pneumococcal disease and in blood from healthy subjects. All cases had detectable antibodies against PspA on admission. We found that invasive pneumococcal disease induced transient T cell depletion but adaptive immune responses strengthened markedly during convalescence. The increased production of both interleukin (IL)-10 and interferon (IFN)-γ during convalescence suggests that these cytokines may be involved in modulating antibody-based immunity to pneumococcal disease. We demonstrated that PspA is efficient at eliciting T cell immune responses and antibodies to PspA. This study broadens the applicability of recombinant PspA as potent pneumococcal antigen for vaccination against S. pneumoniae. PMID:16879247

Glycoconjugates reveal diversity of human neural stem cells (hNSCs) derived from human induced pluripotent stem cells (hiPSCs).

PubMed

Kandasamy, Majury; Roll, Lars; Langenstroth, Daniel; Brüstle, Oliver; Faissner, Andreas

2017-06-01

Neural stem cells (NSCs) have the ability to self-renew and to differentiate into various cell types of the central nervous system. This potential can be recapitulated by human induced pluripotent stem cells (hiPSCs) in vitro. The differentiation capacity of hiPSCs is characterized by several stages with distinct morphologies and the expression of various marker molecules. We used the monoclonal antibodies (mAbs) 487 LeX , 5750 LeX and 473HD to analyze the expression pattern of particular carbohydrate motifs as potential markers at six differentiation stages of hiPSCs. Mouse ESCs were used as a comparison. At the pluripotent stage, 487 LeX -, 5750 LeX - and 473HD-related glycans were differently expressed. Later, cells of the three germ layers in embryoid bodies (hEBs) and, even after neuralization of hEBs, subpopulations of cells were labeled with these surface antibodies. At the human rosette-stage of NSCs (hR-NSC), LeX- and 473HD-related epitopes showed antibody-specific expression patterns. We also found evidence that these surface antibodies could be used to distinguish the hR-NSCs from the hSR-NSCs stages. Characterization of hNSCs FGF-2/EGF derived from hSR-NSCs revealed that both LeX antibodies and the 473HD antibody labeled subpopulations of hNSCs FGF-2/EGF . Finally, we identified potential LeX carrier molecules that were spatiotemporally regulated in early and late stages of differentiation. Our study provides new insights into the regulation of glycoconjugates during early human stem cell development. The mAbs 487 LeX , 5750 LeX and 473HD are promising tools for identifying distinct stages during neural differentiation.

Enzymatic signal amplification for sensitive detection of intracellular antigens by flow cytometry.

PubMed

Karkmann, U; Radbruch, A; Hölzel, V; Scheffold, A

1999-11-19

Flow cytometry is the method of choice for the analysis of single cells with respect to the expression of specific antigens. Antigens can be detected with specific antibodies either on the cell surface or within the cells, after fixation and permeabilization of the cell membrane. Using conventional fluorochrome-labeled antibodies several thousand antigens are required for clear-cut separation of positive and negative cells. More sensitive reagents, e.g., magnetofluorescent liposomes conjugated to specific antibodies permit the detection of less than 200 molecules per cell but cannot be used for the detection of intracellular antigens. Here, we describe an enzymatic amplification technique (intracellular tyramine-based signal amplification, ITSA) for the sensitive cytometric analysis of intracellular cytokines by immunofluorescence. This approach results in a 10 to 15-fold improvement of the signal-to-noise ratio compared to conventional fluorochrome labeled antibodies and permits the detection of as few as 300-400 intracellular antigens per cell.

Pooled protein immunization for identification of cell surface antigens in Streptococcus sanguinis.

PubMed

Ge, Xiuchun; Kitten, Todd; Munro, Cindy L; Conrad, Daniel H; Xu, Ping

2010-07-26

Available bacterial genomes provide opportunities for screening vaccines by reverse vaccinology. Efficient identification of surface antigens is required to reduce time and animal cost in this technology. We developed an approach to identify surface antigens rapidly in Streptococcus sanguinis, a common infective endocarditis causative species. We applied bioinformatics for antigen prediction and pooled antigens for immunization. Forty-seven surface-exposed proteins including 28 lipoproteins and 19 cell wall-anchored proteins were chosen based on computer algorithms and comparative genomic analyses. Eight proteins among these candidates and 2 other proteins were pooled together to immunize rabbits. The antiserum reacted strongly with each protein and with S. sanguinis whole cells. Affinity chromatography was used to purify the antibodies to 9 of the antigen pool components. Competitive ELISA and FACS results indicated that these 9 proteins were exposed on S. sanguinis cell surfaces. The purified antibodies had demonstrable opsonic activity. The results indicate that immunization with pooled proteins, in combination with affinity purification, and comprehensive immunological assays may facilitate cell surface antigen identification to combat infectious diseases.

Pooled Protein Immunization for Identification of Cell Surface Antigens in Streptococcus sanguinis

PubMed Central

Ge, Xiuchun; Kitten, Todd; Munro, Cindy L.; Conrad, Daniel H.; Xu, Ping

2010-01-01

Background Available bacterial genomes provide opportunities for screening vaccines by reverse vaccinology. Efficient identification of surface antigens is required to reduce time and animal cost in this technology. We developed an approach to identify surface antigens rapidly in Streptococcus sanguinis, a common infective endocarditis causative species. Methods and Findings We applied bioinformatics for antigen prediction and pooled antigens for immunization. Forty-seven surface-exposed proteins including 28 lipoproteins and 19 cell wall-anchored proteins were chosen based on computer algorithms and comparative genomic analyses. Eight proteins among these candidates and 2 other proteins were pooled together to immunize rabbits. The antiserum reacted strongly with each protein and with S. sanguinis whole cells. Affinity chromatography was used to purify the antibodies to 9 of the antigen pool components. Competitive ELISA and FACS results indicated that these 9 proteins were exposed on S. sanguinis cell surfaces. The purified antibodies had demonstrable opsonic activity. Conclusions The results indicate that immunization with pooled proteins, in combination with affinity purification, and comprehensive immunological assays may facilitate cell surface antigen identification to combat infectious diseases. PMID:20668678

Linker-free conjugation and specific cell targeting of antibody functionalized iron-oxide nanoparticles

PubMed Central

Xu, Yaolin; Baiu, Dana C.; Sherwood, Jennifer A.; McElreath, Meghan R.; Qin, Ying; Lackey, Kimberly H.; Otto, Mario; Bao, Yuping

2015-01-01

Specific targeting is a key step to realize the full potential of iron oxide nanoparticles in biomedical applications, especially tumor-associated diagnosis and therapy. Here, we developed anti-GD2 antibody conjugated iron oxide nanoparticles for highly efficient neuroblastoma cell targeting. The antibody conjugation was achieved through an easy, linker-free method based on catechol reactions. The targeting efficiency and specificity of the antibody-conjugated nanoparticles to GD2-positive neuroblastoma cells were confirmed by flow cytometry, fluorescence microscopy, Prussian blue staining and transmission electron microscopy. These detailed studies indicated that the receptor-recognition capability of the antibody was fully retained after conjugation and the conjugated nanoparticles quickly attached to GD2-positive cells within four hours. Interestingly, longer treatment (12 h) led the cell membrane-bound nanoparticles to be internalized into cytosol, either by directly penetrating the cell membrane or escaping from the endosomes. Last but importantly, the uniquely designed functional surfaces of the nanoparticles allow easy conjugation of other bioactive molecules. PMID:26660881

Recognition of Naegleriae ameba surface protein epitopes by anti-human CD45 antibodies.

PubMed

Ravine, Terrence J; Polski, Jacek M; Jenkins, James

2010-04-01

Phagocytosis is a highly conserved mechanism exhibited by both free-living amebas and mammalian blood cells. Similarities demonstrated by either cell type during engulfment of the same bacterial species may imply analogous surface proteins involved in receptor-mediated endocytosis. The increased availability of anti-human leukocyte antibodies or clusters of differentiation (CD) markers used in conjunction with flow cytometric (FCM) and/or immunohistochemical (IHC) analysis provides investigators with a relatively easy method to screen different cell populations for comparable plasma membrane proteins. In this study, we incubated Naegleria and Acanthamoeba amebas with several directly conjugated anti-human leukocyte monoclonal antibodies (mAb) for similarly recognized amebic epitopes. CD marker selection was based upon a recognized role of each mAb in phagocyte activation and/or uptake of bacteria. These included CD14, CD45, and CD206. In FCM, only one CD45 antibody demonstrated strong reactivity with both Naegleria fowleri and Naegleria gruberi that was not expressed in similarly tested Acanthamoeba species. Additional testing of N. gruberi by IHC demonstrated reactivity to a different CD45 antibody. Our results suggest a possible utility of using anti-human leukocyte antibodies to screen amebic cells for similarly expressed protein epitopes. In doing so, several important items must be considered when selecting potential mAbs for testing to increase the probability of a positive result.

Blocking immunosuppression by human Tregs in vivo with antibodies targeting integrin αVβ8.

PubMed

Stockis, Julie; Liénart, Stéphanie; Colau, Didier; Collignon, Amandine; Nishimura, Stephen L; Sheppard, Dean; Coulie, Pierre G; Lucas, Sophie

2017-11-21

Human regulatory T cells (Tregs) suppress other T cells by converting the latent, inactive form of TGF-β1 into active TGF-β1. In Tregs, TGF-β1 activation requires GARP, a transmembrane protein that binds and presents latent TGF-β1 on the surface of Tregs stimulated through their T cell receptor. However, GARP is not sufficient because transduction of GARP in non-Treg T cells does not induce active TGF-β1 production. RGD-binding integrins were shown to activate TGF-β1 in several non-T cell types. Here we show that αVβ8 dimers are present on stimulated human Tregs but not in other T cells, and that antibodies against αV or β8 subunits block TGF-β1 activation in vitro. We also show that αV and β8 interact with GARP/latent TGF-β1 complexes in human Tregs. Finally, a blocking antibody against β8 inhibited immunosuppression by human Tregs in a model of xenogeneic graft-vs.-host disease induced by the transfer of human T cells in immunodeficient mice. These results show that TGF-β1 activation on the surface of human Tregs implies an interaction between the integrin αVβ8 and GARP/latent TGF-β1 complexes. Immunosuppression by human Tregs can be inhibited by antibodies against GARP or against the integrin β8 subunit. Such antibodies may prove beneficial against cancer or chronic infections.

Structural biology of antibody recognition of carbohydrate epitopes and potential uses for targeted cancer immunotherapies.

PubMed

Dingjan, Tamir; Spendlove, Ian; Durrant, Lindy G; Scott, Andrew M; Yuriev, Elizabeth; Ramsland, Paul A

2015-10-01

Monoclonal antibodies represent the most successful class of biopharmaceuticals for the treatment of cancer. Mechanisms of action of therapeutic antibodies are very diverse and reflect their ability to engage in antibody-dependent effector mechanisms, internalize to deliver cytotoxic payloads, and display direct effects on cells by lysis or by modulating the biological pathways of their target antigens. Importantly, one of the universal changes in cancer is glycosylation and carbohydrate-binding antibodies can be produced to selectively recognize tumor cells over normal tissues. A promising group of cell surface antibody targets consists of carbohydrates presented as glycolipids or glycoproteins. In this review, we outline the basic principles of antibody-based targeting of carbohydrate antigens in cancer. We also present a detailed structural view of antibody recognition and the conformational properties of a series of related tissue-blood group (Lewis) carbohydrates that are being pursued as potential targets of cancer immunotherapy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Isolation of major pancreatic cell types and long-term culture-initiating cells using novel human surface markers.

PubMed

Dorrell, Craig; Abraham, Stephanie L; Lanxon-Cookson, Kelsea M; Canaday, Pamela S; Streeter, Philip R; Grompe, Markus

2008-09-01

We have developed a novel panel of cell-surface markers for the isolation and study of all major cell types of the human pancreas. Hybridomas were selected after subtractive immunization of Balb/C mice with intact or dissociated human islets and assessed for cell-type specificity and cell-surface reactivity by immunohistochemistry and flow cytometry. Antibodies were identified by specific binding of surface antigens on islet (panendocrine or alpha-specific) and nonislet pancreatic cell subsets (exocrine and duct). These antibodies were used individually or in combination to isolate populations of alpha, beta, exocrine, or duct cells from primary human pancreas by FACS and to characterize the detailed cell composition of human islet preparations. They were also employed to show that human islet expansion cultures originated from nonendocrine cells and that insulin expression levels could be increased to up to 1% of normal islet cells by subpopulation sorting and overexpression of the transcription factors Pdx-1 and ngn3, an improvement over previous results with this culture system. These methods permit the analysis and isolation of functionally distinct pancreatic cell populations with potential for cell therapy.

The antigenic determinants on HIV p24 for CD4+ T cell inhibiting antibodies as determined by limited proteolysis, chemical modification, and mass spectrometry.

PubMed

Williams, Jason G; Tomer, Kenneth B; Hioe, Catarina E; Zolla-Pazner, Susan; Norris, Philip J

2006-11-01

In the last decade, mass spectrometry has been employed by more and more researchers for identifying the proteins in a macromolecular complex as well as for defining the surfaces of their binding interfaces. This characterization of protein-protein interfaces usually involves at least one of several different methodologies in addition to the actual mass spectrometry. For example, limited proteolysis is often used as a first step in defining regions of a protein that are protected from proteolysis when the protein of interest is part of a macromolecular complex. Other techniques used in conjunction with mass spectrometry for determining regions of a protein involved in protein-protein interactions include chemical modification, such as covalent cross-linking, acetylation of lysines, hydrogen-deuterium exchange, or other forms of modification. In this report, both limited proteolysis and chemical modification were combined with several mass spectrometric techniques in efforts to define the protein surface on the HIV core protein, p24, recognized by two different monoclonal human antibodies that were isolated from HIV+ patients. One of these antibodies, 1571, strongly inhibits the CD4+ T cell proliferative response to a known epitope (PEVIPMFSALSEGATP), while the other antibody, 241-D, does not inhibit as strongly. The epitopes for both of these antibodies were determined to be discontinuous and localized to the N-terminus of p24. Interestingly, the epitope recognized by the strongly inhibiting antibody, 1571, completely overlaps the T cell epitope PEVIPMFSALSEGATP, while the antibody 241-D binds to a region adjacent to the region of p24 recognized by the antibody 1571. These results suggest that, possibly due to epitope competition, antibodies produced during HIV infection can negatively affect CD4+ T cell-mediated immunity against the virus.

Surface-modified gold nanorods for specific cell targeting

NASA Astrophysics Data System (ADS)

Wang, Chan-Ung; Arai, Yoshie; Kim, Insun; Jang, Wonhee; Lee, Seonghyun; Hafner, Jason H.; Jeoung, Eunhee; Jung, Deokho; Kwon, Youngeun

2012-05-01

Gold nanoparticles (GNPs) have unique properties that make them highly attractive materials for developing functional reagents for various biomedical applications including photothermal therapy, targeted drug delivery, and molecular imaging. For in vivo applications, GNPs need to be prepared with very little or negligible cytotoxicitiy. Most GNPs are, however, prepared using growth-directing surfactants such as cetyl trimethylammonium bromide (CTAB), which are known to have considerable cytotoxicity. In this paper, we describe an approach to remove CTAB to a non-toxic concentration. We optimized the conditions for surface modification with methoxypolyethylene glycol thiol (mPEG), which replaced CTAB and formed a protective layer on the surface of gold nanorods (GNRs). The cytotoxicities of pristine and surface-modified GNRs were measured in primary human umbilical vein endothelial cells and human cell lines derived from hepatic carcinoma cells, embryonic kidney cells, and thyroid papillary carcinoma cells. Cytotoxicity assays revealed that treating cells with GNRs did not significantly affect cell viability except for thyroid papillary carcinoma cells. Thyroid cancer cells were more susceptible to residual CTAB, so CTAB had to be further removed by dialysis in order to use GNRs for thyroid cell targeting. PEGylated GNRs are further modified to present monoclonal antibodies that recognize a specific surface marker, Na-I symporter, for thyroid cells. Antibody-conjugated GNRs specifically targeted human thyroid cells in vitro.

77 FR 9663 - Agency Information Collection Activities; Proposed Collection; Comment Request; Request for...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-17

... specific licensed biological products: Sec. Sec. 660.6 (21 CFR 660.6) (Antibody to Hepatitis B Surface Antigen); 660.36 (21 CFR 660.36) (Reagent Red Blood Cells); and 660.46 (21 CFR 660.46) (Hepatitis B... each lot of Antibody to Hepatitis B Surface Antigen product, and Sec. 660.6(b) provides the...

The search for new antigenic targets in myasthenia gravis.

PubMed

Cossins, Judith; Belaya, Katsiaryna; Zoltowska, Katarzyna; Koneczny, Inga; Maxwell, Susan; Jacobson, Leslie; Leite, Maria Isabel; Waters, Patrick; Vincent, Angela; Beeson, David

2012-12-01

Around 80% of myasthenia gravis patients have antibodies against the acetylcholine receptor, and 0-60% of the remaining patients have antibodies against the muscle-specific tyrosine kinase, MuSK. Another recently identified antigen is low-density lipoprotein receptor-related protein 4 (Lrp4). To improve the existing assays and widen the search for new antigenic targets, we have employed cell-based assays in which candidate target proteins are expressed on the cell surface of transfected cells and probed with patient sera. These assays, combined with use of myotube cultures to explore the effects of the antibodies, enable us to begin to identify new antigenic targets and test antibody pathogenicity in vitro. © 2012 New York Academy of Sciences.

HIV-1 Vaccines Based on Antibody Identification, B Cell Ontogeny, and Epitope Structure.

PubMed

Kwong, Peter D; Mascola, John R

2018-05-15

HIV-1 vaccine development has been stymied by an inability to induce broadly reactive neutralizing antibodies to the envelope (Env) trimer, the sole viral antigen on the virion surface. Antibodies isolated from HIV-1-infected donors, however, have been shown to recognize all major exposed regions of the prefusion-closed Env trimer, and an emerging understanding of the immunological and structural characteristics of these antibodies and the epitopes they recognize is enabling new approaches to vaccine design. Antibody lineage-based design creates immunogens that activate the naive ancestor-B cell of a target antibody lineage and that mature intermediate-B cells toward effective neutralization, with proof of principle achieved with select HIV-1-neutralizing antibody lineages in human-gene knock-in mouse models. Epitope-based vaccine design involves the engineering of sites of Env vulnerability as defined by the recognition of broadly neutralizing antibodies, with cross-reactive neutralizing antibodies elicited in animal models. Both epitope-based and antibody lineage-based HIV-1 vaccine approaches are being readied for human clinical trials. Published by Elsevier Inc.

Novel Anti-CRR9/CLPTM1L Antibodies with Antitumorigenic Activity Inhibit Cell Surface Accumulation, PI3K Interaction, and Survival Signaling

PubMed Central

Puskás, László G.; Mán, Imola; Szebeni, Gabor; Tiszlavicz, László; Tsai, Susan; James, Michael A.

2016-01-01

We and others have recently shown Cisplatin Resistance-Related Protein 9 (CRR9)/Cleft Lip and Palate Transmembrane 1-Like (CLPTM1L) to affect survival and proliferation in lung and pancreatic tumor cells. Our research has indicated that CLPTM1L affects multiple survival signaling pathways in tumor cells under oncogenic, genotoxic, and microenvironmental stress. We have confirmed the association of CLPTM1L with pancreatic cancer by demonstrating overexpression of CLPTM1L in pancreatic tumors and poor survival in patients with high tumor expression of CLPTM1L. Predicting a transmembrane structure, we determined that CLPTM1L could be targeted at the plasma membrane. Herein, we describe the development of monoclonal antibodies targeting CLPTM1L. Lead antibodies inhibited surface accumulation of CLPTM1L, Akt phosphorylation, anchorage-independent growth, and chemotherapeutic resistance in lung and pancreatic tumor cells. Gemcitabine promoted a physical interaction between CLPTM1L and p110α in pancreatic tumor cells, which was inhibited by anti-CLPTM1L. In-vivo treatment with anti-CLPTM1L robustly inhibited the growth of both lung and pancreatic adenocarcinoma xenografts. The efficacy of anti-CLPTM1L correlated with specific epitopes representing important targets in human cancers, particularly those driven by KRas, for which effective targeted therapies have been elusive. This study is the first to report cell-surface exposure of the tumor survival protein CLPTM1L and inhibition of the function of surface CLPTM1L with novel, systematically developed inhibitory monoclonal antibodies establishing proof of concept of clinically practical agents inhibiting this compelling new tumor survival target in cancer. PMID:26939707

Identification of a Monocyte Receptor on Herpesvirus-Infected Endothelial Cells

NASA Astrophysics Data System (ADS)

Etingin, Orli R.; Silverstein, Roy L.; Hajjar, David P.

1991-08-01

The adhesion of circulating blood cells to vascular endothelium may be an initial step in atherosclerosis, inflammation, and wound healing. One mechanism for promoting cell-cell adhesion involves the expression of adhesion molecules on the surface of the target cell. Herpes simplex virus infection of endothelium induces arterial injury and has been implicated in the development of human atherosclerosis. We now demonstrate that HSV-infected endothelial cells express the adhesion molecule GMP140 and that this requires cell surface expression of HSV glycoprotein C and local thrombin generation. Monocyte adhesion to HSV-infected endothelial cells was completely inhibited by anti-GMP140 antibodies but not by antibodies to other adhesion molecules such as VCAM and ELAM-1. The induction of GMP140 expression on HSV-infected endothelium may be an important pathophysiological mechanism in virus-induced cell injury and inflammation.

Bovine apolipoprotein B-100 is a dominant immunogen in therapeutic cell populations cultured in fetal calf serum in mice and humans

PubMed Central

Sakamoto, Norihisa; Tsuji, Kazuhide; Muul, Linda M.; Lawler, Ann M.; Petricoin, Emanuel F.; Candotti, Fabio; Metcalf, Julia A.; Tavel, Jorge A.; Lane, H. Clifford; Urba, Walter J.; Fox, Bernard A.; Varki, Ajit; Lunney, Joan K.

2007-01-01

Recent studies have demonstrated that cell populations intended for therapeutic purposes that are cultured in heterologous animal products can acquire xenoantigens, potentially limiting their utility. In investigations of the immune response to murine embryonic stem cells, we found that a strong antibody response was generated after the second infusion. Both polyclonal and monoclonal antibody responses, derived from immunized mice, were found to be specific for bovine apolipoprotein B-100, which binds to abundant low-density lipoprotein receptors on the cell surface and is internalized. Here we show that in the majority of patients administered 3 different types of cell-based therapies using cells grown in fetal calf serum-containing media, an antibody response to bovine apolipoprotein B-100 develops after the second infusion and is the dominant specificity. The known and potential clinical effects of such antibodies are discussed. PMID:17395779

Antibody-Dependent Cell-Mediated Cytotoxicity Effector-Enhanced EphA2 Agonist Monoclonal Antibody Demonstrates Potent Activity against Human Tumors1

PubMed Central

Bruckheimer, Elizabeth M; Fazenbaker, Christine A; Gallagher, Sandra; Mulgrew, Kathy; Fuhrmann, Stacy; Coffman, Karen T; Walsh, William; Ready, Shannon; Cook, Kim; Damschroder, Melissa; Kinch, Michael; Kiener, Peter A; Woods, Rob; Gao, Changshou; Dall'Acqua, William; Wu, Herren; Coats, Steven

2009-01-01

EphA2 is a receptor tyrosine kinase that has been shown to be overexpressed in a variety of human tumor types. Previous studies demonstrated that agonist monoclonal antibodies targeting EphA2 induced the internalization and degradation of the receptor, thereby abolishing its oncogenic effects. In this study, the in vitro and in vivo antibody-dependent cell-mediated cytotoxicity (ADCC) activity of EphA2 effector-enhanced agonist monoclonal antibodies was evaluated. With tumor cell lines and healthy human peripheral blood monocytes, the EphA2 antibodies demonstrated ∼80% tumor cell killing. In a dose-dependent manner, natural killer (NK) cells were required for the in vitro ADCC activity and became activated as demonstrated by the induction of cell surface expression of CD107a. To assess the role of NK cells on antitumor efficacy in vivo, the EphA2 antibodies were evaluated in xenograft models in severe compromised immunodeficient (SCID) mice (which have functional NK cells and monocytes) and SCID nonobese diabetic (NOD) mice (which largely lack functional NK cells and monocytes). Dosing of EphA2 antibody in the SCID murine tumor model resulted in a 6.2-fold reduction in tumor volume, whereas the SCID/nonobese diabetic model showed a 1.6-fold reduction over the isotype controls. Together, these results demonstrate that the anti-EphA2 monoclonal antibodies may function through at least two mechanisms of action: EphA2 receptor activation and ADCC-mediated activity. These novel EphA2 monoclonal antibodies provide additional means by which host effector mechanisms can be activated for selective destruction of EphA2-expressing tumor cells. PMID:19484140

Novel method for in vitro depletion of T cells by monoclonal antibody-targeted photosensitization.

PubMed

Berki, T; Németh, P

1998-02-01

An immunotargeting method (called photo-immunotargeting) has been developed for selective in vitro cell destruction. The procedure combines the photosensitizing (toxic) effect of light-induced dye-molecules, e.g., hematoporphyrin (HP) and the selective binding ability of monoclonal antibodies (mAb) to cell surface molecules. The photosensitizer HP molecules were covalently attached to monoclonal antibodies (a-Thy-1) recognizing an antigen on the surface of T lymphocytes, and used for T cell destruction. To increase the selectivity of the conventional targeting methods, a physical activation step (local light irradiation) as a second degree of specificity was employed. The HP in conjugated form was sufficient to induce T cell (thymocytes, EL-4 cell line) death after irradiation at 400 nm, at tenfold lower concentration compared to the photosensitizing effect of unbound HP. The selective killing of T lymphocytes (bearing the Thy-1 antigen) in a mixed cell population was demonstrated after a treatment with the phototoxic conjugate and light irradiation. This method can be useful for selective destruction of one population (target cell) in an in vitro heterogeneous cell mixture, e.g., in bone marrow transplants for T cell depletion to avoid graft vs. host reaction.

Quantitative Analysis of Endocytic Recycling of Membrane Proteins by Monoclonal Antibody-Based Recycling Assays.

PubMed

Blagojević Zagorac, Gordana; Mahmutefendić, Hana; Maćešić, Senka; Karleuša, Ljerka; Lučin, Pero

2017-03-01

In this report, we present an analysis of several recycling protocols based on labeling of membrane proteins with specific monoclonal antibodies (mAbs). We analyzed recycling of membrane proteins that are internalized by clathrin-dependent endocytosis, represented by the transferrin receptor, and by clathrin-independent endocytosis, represented by the Major Histocompatibility Class I molecules. Cell surface membrane proteins were labeled with mAbs and recycling of mAb:protein complexes was determined by several approaches. Our study demonstrates that direct and indirect detection of recycled mAb:protein complexes at the cell surface underestimate the recycling pool, especially for clathrin-dependent membrane proteins that are rapidly reinternalized after recycling. Recycling protocols based on the capture of recycled mAb:protein complexes require the use of the Alexa Fluor 488 conjugated secondary antibodies or FITC-conjugated secondary antibodies in combination with inhibitors of endosomal acidification and degradation. Finally, protocols based on the capture of recycled proteins that are labeled with Alexa Fluor 488 conjugated primary antibodies and quenching of fluorescence by the anti-Alexa Fluor 488 displayed the same quantitative assessment of recycling as the antibody-capture protocols. J. Cell. Physiol. 232: 463-476, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

ELECTRON MICROSCOPE STUDY OF SURFACE IMMUNOGLOBULIN-BEARING HUMAN TONSIL CELLS

PubMed Central

Zucker-Franklin, Dorothea; Berney, Steven

1972-01-01

Surface immunoglobulin-bearing cells were selected from suspensions of human tonsil cells by the reverse immune cytoadherence technique. The method employed a hybrid antibody directed against Ig on lymphoid cells and against ferritin bound to sheep red blood cells (SRBC). Only 6% of the cells formed rosettes. When subjected to electron microscopy they were shown to consist of a morphologically heterogeneous population of cells. However, most cells in the center of rosettes showed ribosome-associated endoplasmic reticulum (RER) and polyribosomes. Usually these organelles were located in close proximity to membrane sites where a 400–600 A bridge was resolved between the lymphocyte and the ferritin particle on the SRBC. The bridge is postulated to consist at least in part of Ig. Only 50% of the plasma cells formed rosettes and bridges could not be resolved. The surface of the plasma cells within rosettes differed from that of plasma cells which had not reacted with ferritin-coated sheep erythrocytes. The incidence of plasma cells and γ-globulin-bearing lymphoid cells was corroborated with the help of fluorescent antibody techniques. PMID:5061976

B-cell acquisition of antigen: Sensing the surface.

PubMed

Knight, Andrew M

2015-06-01

B-cell antigen receptor (BCR) recognition and acquisition of antigen by B cells is the essential first step in the generation of effective antibody responses. As B-cell-mediated antigen presentation is also believed to play a significant role in the activation of CD4(+) Th-cell responses, considerable effort has focused on clarifying the nature of antigen/BCR interactions. Following earlier descriptions of interactions of soluble antigens with the BCR, it is now clear that B cells also recognize, physically extract and present antigens that are tethered to, or integral components of, the surfaces or extracellular matrix of other cells. In this issue of the European Journal of Immunology, Zeng et al. [Eur. J. Immunol. 2015. 45: XXXX-XXXX] examine how the physical property or "stiffness" of the surface displaying antigens to B cells influences the B-cell response. This commentary reports that antigen tethered on "less stiff" surfaces induces increased B-cell activation and antibody responses. I then infer how "sensing the surface" by B cells may represent a new component of the immune system's ability to detect "damage," and how this understanding may influence approaches to clinical therapies where immune activity is either unwanted or desired. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single-cell analysis and sorting using droplet-based microfluidics.

PubMed

Mazutis, Linas; Gilbert, John; Ung, W Lloyd; Weitz, David A; Griffiths, Andrew D; Heyman, John A

2013-05-01

We present a droplet-based microfluidics protocol for high-throughput analysis and sorting of single cells. Compartmentalization of single cells in droplets enables the analysis of proteins released from or secreted by cells, thereby overcoming one of the major limitations of traditional flow cytometry and fluorescence-activated cell sorting. As an example of this approach, we detail a binding assay for detecting antibodies secreted from single mouse hybridoma cells. Secreted antibodies are detected after only 15 min by co-compartmentalizing single mouse hybridoma cells, a fluorescent probe and single beads coated with anti-mouse IgG antibodies in 50-pl droplets. The beads capture the secreted antibodies and, when the captured antibodies bind to the probe, the fluorescence becomes localized on the beads, generating a clearly distinguishable fluorescence signal that enables droplet sorting at ∼200 Hz as well as cell enrichment. The microfluidic system described is easily adapted for screening other intracellular, cell-surface or secreted proteins and for quantifying catalytic or regulatory activities. In order to screen ∼1 million cells, the microfluidic operations require 2-6 h; the entire process, including preparation of microfluidic devices and mammalian cells, requires 5-7 d.

Single-cell analysis and sorting using droplet-based microfluidics

PubMed Central

Mazutis, Linas; Gilbert, John; Ung, W Lloyd; Weitz, David A; Griffiths, Andrew D; Heyman, John A

2014-01-01

We present a droplet-based microfluidics protocol for high-throughput analysis and sorting of single cells. compartmentalization of single cells in droplets enables the analysis of proteins released from or secreted by cells, thereby overcoming one of the major limitations of traditional flow cytometry and fluorescence-activated cell sorting. as an example of this approach, we detail a binding assay for detecting antibodies secreted from single mouse hybridoma cells. secreted antibodies are detected after only 15 min by co-compartmentalizing single mouse hybridoma cells, a fluorescent probe and single beads coated with anti-mouse IgG antibodies in 50-pl droplets. the beads capture the secreted antibodies and, when the captured antibodies bind to the probe, the fluorescence becomes localized on the beads, generating a clearly distinguishable fluorescence signal that enables droplet sorting at ~200 Hz as well as cell enrichment. the microfluidic system described is easily adapted for screening other intracellular, cell-surface or secreted proteins and for quantifying catalytic or regulatory activities. In order to screen ~1 million cells, the microfluidic operations require 2–6 h; the entire process, including preparation of microfluidic devices and mammalian cells, requires 5–7 d. PMID:23558786

Netrin-1 receptor antibodies in thymoma-associated neuromyotonia with myasthenia gravis.

PubMed

Torres-Vega, Estefanía; Mancheño, Nuria; Cebrián-Silla, Arantxa; Herranz-Pérez, Vicente; Chumillas, María J; Moris, Germán; Joubert, Bastien; Honnorat, Jérôme; Sevilla, Teresa; Vílchez, Juan J; Dalmau, Josep; Graus, Francesc; García-Verdugo, José Manuel; Bataller, Luis

2017-03-28

To identify cell-surface antibodies in patients with neuromyotonia and to describe the main clinical implications. Sera of 3 patients with thymoma-associated neuromyotonia and myasthenia gravis were used to immunoprecipitate and characterize neuronal cell-surface antigens using reported techniques. The clinical significance of antibodies against precipitated proteins was assessed with sera of 98 patients (neuromyotonia 46, myasthenia gravis 52, thymoma 42; 33 of them with overlapping syndromes) and 219 controls (other neurologic diseases, cancer, and healthy volunteers). Immunoprecipitation studies identified 3 targets, including the Netrin-1 receptors DCC (deleted in colorectal carcinoma) and UNC5A (uncoordinated-5A) as well as Caspr2 (contactin-associated protein-like 2). Cell-based assays with these antigens showed that among the indicated patients, 9 had antibodies against Netrin-1 receptors (7 with additional Caspr2 antibodies) and 5 had isolated Caspr2 antibodies. Only one of the 219 controls had isolated Caspr2 antibodies with relapsing myelitis episodes. Among patients with neuromyotonia and/or myasthenia gravis, the presence of Netrin-1 receptor or Caspr2 antibodies predicted thymoma ( p < 0.05). Coexisting Caspr2 and Netrin-1 receptor antibodies were associated with concurrent thymoma, myasthenia gravis, and neuromyotonia, often with Morvan syndrome ( p = 0.009). Expression of DCC, UNC5A, and Caspr2 proteins was demonstrated in paraffin-embedded thymoma samples (3) and normal thymus. Antibodies against Netrin-1 receptors (DCC and UNC5a) and Caspr2 often coexist and associate with thymoma in patients with neuromyotonia and myasthenia gravis. This study provides Class III evidence that antibodies against Netrin-1 receptors can identify patients with thymoma (sensitivity 21.4%, specificity 100%). © 2017 American Academy of Neurology.

Netrin-1 receptor antibodies in thymoma-associated neuromyotonia with myasthenia gravis

PubMed Central

Torres-Vega, Estefanía; Mancheño, Nuria; Cebrián-Silla, Arantxa; Herranz-Pérez, Vicente; Chumillas, María J.; Moris, Germán; Joubert, Bastien; Honnorat, Jérôme; Sevilla, Teresa; Vílchez, Juan J.; Dalmau, Josep; Graus, Francesc; García-Verdugo, José Manuel

2017-01-01

Objective: To identify cell-surface antibodies in patients with neuromyotonia and to describe the main clinical implications. Methods: Sera of 3 patients with thymoma-associated neuromyotonia and myasthenia gravis were used to immunoprecipitate and characterize neuronal cell-surface antigens using reported techniques. The clinical significance of antibodies against precipitated proteins was assessed with sera of 98 patients (neuromyotonia 46, myasthenia gravis 52, thymoma 42; 33 of them with overlapping syndromes) and 219 controls (other neurologic diseases, cancer, and healthy volunteers). Results: Immunoprecipitation studies identified 3 targets, including the Netrin-1 receptors DCC (deleted in colorectal carcinoma) and UNC5A (uncoordinated-5A) as well as Caspr2 (contactin-associated protein-like 2). Cell-based assays with these antigens showed that among the indicated patients, 9 had antibodies against Netrin-1 receptors (7 with additional Caspr2 antibodies) and 5 had isolated Caspr2 antibodies. Only one of the 219 controls had isolated Caspr2 antibodies with relapsing myelitis episodes. Among patients with neuromyotonia and/or myasthenia gravis, the presence of Netrin-1 receptor or Caspr2 antibodies predicted thymoma (p < 0.05). Coexisting Caspr2 and Netrin-1 receptor antibodies were associated with concurrent thymoma, myasthenia gravis, and neuromyotonia, often with Morvan syndrome (p = 0.009). Expression of DCC, UNC5A, and Caspr2 proteins was demonstrated in paraffin-embedded thymoma samples (3) and normal thymus. Conclusions: Antibodies against Netrin-1 receptors (DCC and UNC5a) and Caspr2 often coexist and associate with thymoma in patients with neuromyotonia and myasthenia gravis. Classification of evidence: This study provides Class III evidence that antibodies against Netrin-1 receptors can identify patients with thymoma (sensitivity 21.4%, specificity 100%). PMID:28251919

CD28 is an Inducible T Cell Surface Antigen that Transduces a Proliferative Signal in CD3(+) Mature Thymocytes

DTIC Science & Technology

1990-03-01

tion of both CD3 thymocytes and peripheral blood fashion by antibodies with specificity directed at con- T cells. This increase was accounted for by a...of mature tamined by the panning technique. Briefly. anti-CD3 antibody was T cells, whereas not directly mitogenic (23), synergizes immobilized on...thymocytes are CD28 . but cultured at a density of I x 10’/ml. When used. anti-CD3 antibody that it is found in high density only on the CD3 5h was

Peripheral neuropathies associated with antibodies directed to intracellular neural antigens.

PubMed

Antoine, J-C

2014-10-01

Antibodies directed to intracellular neural antigens have been mainly described in paraneoplastic peripheral neuropathies and mostly includes anti-Hu and anti-CV2/CRMP5 antibodies. These antibodies occur with different patterns of neuropathy. With anti-Hu antibody, the most frequent manifestation is sensory neuronopathy with frequent autonomic involvement. With anti-CV2/CRMP5 the neuropathy is more frequently sensory and motor with an axonal or mixed demyelinating and axonal electrophysiological pattern. The clinical pattern of these neuropathies is in keeping with the cellular distribution of HuD and CRMP5 in the peripheral nervous system. Although present in high titer, these antibodies are probably not directly responsible for the neuropathy. Pathological and experimental studies indicate that cytotoxic T-cells are probably the main effectors of the immune response. These disorders contrast with those in which antibodies recognize a cell surface antigen and are probably responsible for the disease. The neuronal cell death and axonal degeneration which result from T-cell mediated immunity explains why treating these disorders remains challenging. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Detection of squamous carcinoma cells using gold nanoparticles

NASA Astrophysics Data System (ADS)

Dai, Wei-Yun; Lee, Sze-tsen; Hsu, Yih-Chih

2015-03-01

The goal of this study is to use gold nanoparticle as a diagnostic agent to detect human squamous carcinoma cells. Gold nanoparticles were synthesized and the gold nanoparticle size was 34.3 ± 6.2 nm. Based on the over-expression of epidermal growth factor receptor (EGFR) biomarkers in squamous carcinoma cells, we hypothesized that EGFR could be a feasible biomarker with a target moiety for detection. We further modified polyclonal antibodies of EGFR on the surface of gold nanoparticles. We found selected squamous carcinoma cells can be selectively detected using EGFR antibody-modified gold nanoparticles via receptor-mediated endocytosis. Cell death was also examined to determine the survival status of squamous carcinoma cells with respect to gold nanoparticle treatment and EGFR polyclonal antibody modification.

Immunomicrospheres - Reagents for cell labeling and separation

NASA Technical Reports Server (NTRS)

Rembaum, A.; Dreyer, W. J.

1980-01-01

Immunomicrospheres are specially designed microscopic particles that have antibodies or similar molecules chemically bound to their surfaces. The antibody-coated microspheres react in a highly specific way with target cells, viruses, or other antigenic agents. Immunomicrospheres may be synthesized so that they incorporate compounds that are highly radioactive, intensely fluorescent, magnetic, electron opaque, highly colored, or pharmacologically active. These various types of microspheres may be coated with pure, highly specific monoclonal antibodies obtained by the new hybridoma cell cloning techniques or with conventional antibody preparations. Some of the many present and potential applications for these new reagents are (1) new types of radioimmune or immunofluorescent assays, (2) improved fluorescence microscopy, (3) separation of cells on the basis of the fluorescent, electrophoretic, or magnetic properties of bound immunomicrospheres, (4) markers for use in several types of electron or standard light microscopy, and (5) delivery of lethal compouds to specific undesirable living cells. The combination of the various new types of synthetic microspheres and the newly available homogeneous antibodies offers new opportunities in research, diagnosis, and therapy.

Isolation by cell-column chromatography of immunoglobulins specific for cell surface carbohydrates

PubMed Central

1977-01-01

A new method of affinity chromatography using glutaraldehyde-fixed cells immobilized on Sephadex beads has been used to isolate immunoglobulins (Ig's) specific for cell surface glycoproteins. Ig's that specifically bound and agglutinated the same cells as those originally fixed on the columns were isolated from nonimmune sera of various species. Periodate treatment of the cell-columns and the free cells destroyed their ability to bind the Ig's, and the binding of the Ig's to untreated cells was inhibited by monosaccharides such as D- galactose and sialic acid. The binding of antibodies directed against cell surfaces obtained by immunizing animals with the same mouse tumor cell lines used on the columns (P388 and EL4) was not inhibited by various saccharides. Surface glycoproteins obtained from the mouse tumor cells by immunoprecipitation with the column-isolated Ig's yielded specific electrophoretic patterns that differed from those obtained using Ig's from the sera of rabbits immunized with the tumor cells. The data suggest that the Ig's isolated by cell-column chromatography were directed against carbohydrates, probably those in terminal positions of the polysaccharide portions of the tumor cell surface glycoproteins. Column-isolated Ig's specific for carbohydrates were also useful in studies of cell interactions in nonmammalian systems including Dictyostelium discoideum and Saccharomyces cerevisiae. The cell-column method appears to be adaptable to the isolation of a variety of molecules in addition to antibodies. PMID:833547

New Monoclonal Antibodies to Defined Cell Surface Proteins on Human Pluripotent Stem Cells.

PubMed

O'Brien, Carmel M; Chy, Hun S; Zhou, Qi; Blumenfeld, Shiri; Lambshead, Jack W; Liu, Xiaodong; Kie, Joshua; Capaldo, Bianca D; Chung, Tung-Liang; Adams, Timothy E; Phan, Tram; Bentley, John D; McKinstry, William J; Oliva, Karen; McMurrick, Paul J; Wang, Yu-Chieh; Rossello, Fernando J; Lindeman, Geoffrey J; Chen, Di; Jarde, Thierry; Clark, Amander T; Abud, Helen E; Visvader, Jane E; Nefzger, Christian M; Polo, Jose M; Loring, Jeanne F; Laslett, Andrew L

2017-03-01

The study and application of human pluripotent stem cells (hPSCs) will be enhanced by the availability of well-characterized monoclonal antibodies (mAbs) detecting cell-surface epitopes. Here, we report generation of seven new mAbs that detect cell surface proteins present on live and fixed human ES cells (hESCs) and human iPS cells (hiPSCs), confirming our previous prediction that these proteins were present on the cell surface of hPSCs. The mAbs all show a high correlation with POU5F1 (OCT4) expression and other hPSC surface markers (TRA-160 and SSEA-4) in hPSC cultures and detect rare OCT4 positive cells in differentiated cell cultures. These mAbs are immunoreactive to cell surface protein epitopes on both primed and naive state hPSCs, providing useful research tools to investigate the cellular mechanisms underlying human pluripotency and states of cellular reprogramming. In addition, we report that subsets of the seven new mAbs are also immunoreactive to human bone marrow-derived mesenchymal stem cells (MSCs), normal human breast subsets and both normal and tumorigenic colorectal cell populations. The mAbs reported here should accelerate the investigation of the nature of pluripotency, and enable development of robust cell separation and tracing technologies to enrich or deplete for hPSCs and other human stem and somatic cell types. Stem Cells 2017;35:626-640. © 2016 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Correlation of Cell Surface Biomarker Expression Levels with Adhesion Contact Angle Measured by Lateral Microscopy.

PubMed

Walz, Jenna A; Mace, Charles R

2018-06-05

Immunophenotyping is typically achieved using flow cytometry, but any influence a biomarker may have on adhesion or surface recognition cannot be determined concurrently. In this manuscript, we demonstrate the utility of lateral microscopy for correlating cell surface biomarker expression levels with quantitative descriptions of cell morphology. With our imaging system, we observed single cells from two T cell lines and two B cell lines adhere to antibody-coated substrates and quantified this adhesion using contact angle measurements. We found that SUP-T1 and CEM CD4+ cells, both of which express similar levels of CD4, experienced average changes in contact angle that were not statistically different from one another on surfaces coated in anti-CD4. However, MAVER-1 and BJAB K20 cells, both of which express different levels of CD20, underwent average changes in contact angle that were significantly different from one another on surfaces coated in anti-CD20. Our results indicate that changes in cell contact angles on antibody-coated substrates reflect the expression levels of corresponding antigens on the surfaces of cells as determined by flow cytometry. Our lateral microscopy approach offers a more reproducible and quantitative alternative to evaluate adhesion compared to commonly used wash assays and can be extended to many additional immunophenotyping applications to identify cells of interest within heterogeneous populations.

Application of surface plasmon resonance biosensor for the detection of Candida albicans

NASA Astrophysics Data System (ADS)

Yodmongkol, Sirasa; Thaweboon, Sroisiri; Thaweboon, Boonyanit; Puttharugsa, Chokchai; Sutapun, Boonsong; Amarit, Ratthasart; Somboonkaew, Armote; Srikhirin, Toemsak

2016-02-01

In this study, surface plasmon resonance imaging (SPR imaging) was developed for the detection of Candida albicans which is a causal agent of oral infection. The detection was based on the sandwich assay. The capture antibody was covalently immobilized on the mixed self assemble monolayers (SAMs). The ratio of mixed SAMs between 11-mercaptoundecanoic acid and 3-mercaptopropanol was varied to find the optimal ratio for use as a sensor surface. The results showed that the suitable surface for C. albicans detection was SAM of carboxylic (mixed SAMs 1:0), even though mixed SAMs 1:40 had a high detection signal in comparison to mixed SAMs 1:0, but the non-specific signal was higher. The detection limit was 107 cells/ml for direct detection, and was increased to 106 cells/ml with sandwich antibody. The use of polyclonal C. albicans antibody as capture and sandwich antibody showed good selectivity against the relevant oral bacteria including Escherichia coli, Streptococcus mutan, Staphylococcus aureus, β-streptococci, and Lactobacillus casei. SPR platform in this study could detect C. albicans from the mixed microbial suspension without requirement of skillful technician. This SPR imaging biosensor could be applied for Candida identification after cultivation.

Glucocorticoids suppress calcium mobilization and phospholipid hydrolysis in anti-Ig antibody-stimulated B cells.

PubMed

Dennis, G; June, C H; Mizuguchi, J; Ohara, J; Witherspoon, K; Finkelman, F D; McMillan, V; Mond, J J

1987-10-15

Glucocorticoids have been shown to play a major role in influencing the activation of B lymphocytes. In view of our recent observation that dexamethasone exerts a marked suppressive effect on an early event in B cell activation that is stimulated by anti-Ig antibody, we investigated its activity on other stimuli that induce intracellular events similar to those produced by anti-Ig antibody. Because the intracellular events that occur after B cell stimulation with phorbol myristate acetate and the calcium ionophore A23187 appear to mimic those that occur after B cell stimulation with anti-Ig antibody, we studied whether the cellular responses elicited by these activation stimuli are affected in a similar fashion by dexamethasone. Whereas anti-Ig antibody-stimulated entry of G0 B cells to the G1 and S phase of the cell cycle was markedly suppressed by dexamethasone, phorbol myristate acetate/A23187 stimulation of these events was resistant to dexamethasone. Our finding that anti-Ig-induced cross-linking of B cell surface Ig, as measured by surface Ig capping, was not inhibited by dexamethasone suggested that corticosteroids inhibit anti-Ig-induced B cell proliferation at a step distal to membrane Ig cross-linking and proximal to phosphatidylinositol bisphosphate hydrolysis. This hypothesis is supported by experiments presented in this manuscript which demonstrate that dexamethasone inhibits anti-Ig-stimulated phosphatidylinositol bisphosphate hydrolysis. We also found that dexamethasone markedly inhibited anti-Ig antibody-stimulated increases in intracellular ionized calcium concentrations. This dexamethasone-mediated suppression is time-dependent as it is not seen when B cells are cultured with dexamethasone for less than 6 hr. Our data suggest that the immunomodulatory activity of glucocorticoids is exerted by binding to its nuclear receptor, thereby preventing the generation of second messengers required for cell activation after agonist-receptor interaction.

GPI-anchored GFP signals Ca2+ but is homogeneously distributed on the cell surface.

PubMed

Hiscox, Stephen; Hallett, Maurice B; Morgan, B Paul; van den Berg, Carmen W

2002-05-03

Glycosyl-phosphatidylinositol (GPI)-anchored proteins are unique in that they penetrate only the outer leaflet of the plasma membrane but are still able to mediate intracellular signalling events following antibody-induced ligation. Detergent solubilisation studies suggest that microdomains exist at the cell surface within which are sequestered GPI-linked proteins. Here we report the construction and expression of a fluorescent GPI anchor on the surface of CHO, EL4, and U937 cells by fusing green fluorescent protein (GFP) to the GPI-attachment site of CD59. The resultant GFP-GPI has properties comparable to that of endogenously expressed GPI-anchored molecules as shown by Triton X-114 partitioning. However, sucrose gradient floatation showed that GFP-GPI was only partially resistant to detergent solubilisation. Furthermore confocal scanning laser microscopy revealed a homogeneous distribution of GFP-GPI at the cell surface, which only became clustered following cross-linking of the GPI anchor via an anti-GFP antibody. Surprisingly, GFP-GPI signalled Ca2+ change upon cross-linking demonstrating its signalling competence. Our results suggest that the GPI-anchor itself does not confer a clustered distribution to molecules but that clustering occurs following ligation with antibody, which allows the protein to become Ca2+ signalling competent. Copyright 2002 Elsevier Science (USA).

Development of T follicular helper cells and their role in disease and immune system.

PubMed

Eivazi, Sadegh; Bagheri, Salman; Hashemzadeh, Mohammad Sadegh; Ghalavand, Majdedin; Qamsari, Elmira Safaie; Dorostkar, Ruhollah; Yasemi, Maryam

2016-12-01

The T follicular helper cells (TFH) are a subset of CD4+ T cells specialized to regulate antibody responses. The production of these cells is associated with the dendritic cells (DCs) and B cells. TFH cells help B cells form germinal centers (GC) differentiate into memory and plasma cells (antibody-secreting cells) as humoral responses. In addition, there is strong evidence that TFH cells play a pivotal role in the development of long-lived humoral immunity. Molecular factors such as transcription factors, surface receptors, cytokine and micro RNAs are involved in the formation of TFH cells. Such TFH cells are diagnosed by transcription factor (BCL-6), surface marker expression (including CXCR5, PD-1, ICOS and CD40L) and a unique cytokine production pattern (such as IL-21 and IL-6). Memory TFH cells, accompanied by memory B cells, are known to be formed during antibody responses. It is now clear that the precise control of TFH cells is critically important for both inducing the optimal affinity maturation of antibody responses and preventing self-reactivity. Exclusive controls of TFH cell function and production are essential for human health. However, it is important to note that excessive activities may lead to autoimmune diseases, while reduced activity often results in immunodeficiency. It has also been shown that TFH cells are associated with cancers such as angioimmunoblastic T-cell lymphoma (AITL), follicular T-cell lymphoma (FTCL) and nonspecific Peripheral T-cell lymphomas (PTCLs). The biology of TFH cells, including their differentiation and transcriptional regulation will be described in the present review. Some of The developments of these cells in immunodeficiency diseases, autoimmunity and cancer will also be taken into account. Copyright © 2016. Published by Elsevier Masson SAS.

Mapping the distribution of specific antibody interaction forces on individual red blood cells

NASA Astrophysics Data System (ADS)

Yeow, Natasha; Tabor, Rico F.; Garnier, Gil

2017-02-01

Current blood typing methods rely on the agglutination of red blood cells (RBCs) to macroscopically indicate a positive result. An indirect agglutination mechanism is required when blood typing with IgG forms of antibodies. To date, the interaction forces between anti-IgG and IgG antibodies have been poorly quantified, and blood group related antigens have never been quantified with the atomic force microscope (AFM). Instead, the total intensity resulting from fluorescent-tagged antibodies adsorbed on RBC has been measured to calculate an average antigen density on a series of RBCs. In this study we mapped specific antibody interaction forces on the RBC surface. AFM cantilever tips functionalized with anti-IgG were used to probe RBCs incubated with specific IgG antibodies. This work provides unique insight into antibody-antigen interactions in their native cell-bound location, and crucially, on a per-cell basis rather than an ensemble average set of properties. Force profiles obtained from the AFM directly provide not only the anti-IgG - IgG antibody interaction force, but also the spatial distribution and density of antigens over a single cell. This new understanding might be translated into the development of very selective and quantitative interactions that underpin the action of drugs in the treatment of frontier illnesses.

Investigating interactions between phospholipase B-Like 2 and antibodies during Protein A chromatography.

PubMed

Tran, Benjamin; Grosskopf, Vanessa; Wang, Xiangdan; Yang, Jihong; Walker, Don; Yu, Christopher; McDonald, Paul

2016-03-18

Purification processes for therapeutic antibodies typically exploit multiple and orthogonal chromatography steps in order to remove impurities, such as host-cell proteins. While the majority of host-cell proteins are cleared through purification processes, individual host-cell proteins such as Phospholipase B-like 2 (PLBL2) are more challenging to remove and can persist into the final purification pool even after multiple chromatography steps. With packed-bed chromatography runs using host-cell protein ELISAs and mass spectrometry analysis, we demonstrated that different therapeutic antibodies interact to varying degrees with host-cell proteins in general, and PLBL2 specifically. We then used a high-throughput Protein A chromatography method to further examine the interaction between our antibodies and PLBL2. Our results showed that the co-elution of PLBL2 during Protein A chromatography is highly dependent on the individual antibody and PLBL2 concentration in the chromatographic load. Process parameters such as antibody resin load density and pre-elution wash conditions also influence the levels of PLBL2 in the Protein A eluate. Furthermore, using surface plasmon resonance, we demonstrated that there is a preference for PLBL2 to interact with IgG4 subclass antibodies compared to IgG1 antibodies. Copyright © 2016 Elsevier B.V. All rights reserved.

3β-Hydroxysterol Δ24-Reductase on the Surface of Hepatitis C Virus-Related Hepatocellular Carcinoma Cells Can Be a Target for Molecular Targeting Therapy

PubMed Central

Saito, Makoto; Takano, Takashi; Nishimura, Tomohiro; Kohara, Michinori; Tsukiyama-Kohara, Kyoko

2015-01-01

In our previous study, we demonstrated that 3β-hydroxysterol Δ24-reductase (DHCR24) was overexpressed in hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC), and that its expression was induced by HCV. Using a monoclonal antibody against DHCR24 (2-152a MAb), we found that DHCR24 was specifically expressed on the surface of HCC cell lines. Based on these findings, we aimed to establish a novel targeting strategy using 2-152a MAb to treat HCV-related HCC. In the present study, we examined the antitumor activity of 2-152a MAb. In the presence of complement, HCC-derived HuH-7 cells were killed by treatment with 2-152a MAb, which was mediated by complement-dependent cytotoxicity (CDC). In addition, the antigen recognition domain of 2-152a MAb was responsible for the unique anti-HCV activity. These findings demonstrate the feasibility of using 2-152a MAb for antibody therapy against HCV-related HCC. In addition, surface DHCR24 on HCC cells exhibited a functional property, agonist-induced internalization. We showed that 2-152a MAb-mediated binding of a cytotoxic agent (a saponin-conjugated secondary antibody) to surface DHCR24 led to significant cytotoxicity. This suggests that surface DHCR24 on HCC cells can function as a carrier for internalization. Therefore, surface DHCR24 could be a valuable target for HCV-related HCC therapy, and 2-152a MAb appears to be useful for this targeted therapy. PMID:25875901

Efficient generation of monoclonal antibodies from single rhesus macaque antibody secreting cells.

PubMed

Meng, Weixu; Li, Leike; Xiong, Wei; Fan, Xuejun; Deng, Hui; Bett, Andrew J; Chen, Zhifeng; Tang, Aimin; Cox, Kara S; Joyce, Joseph G; Freed, Daniel C; Thoryk, Elizabeth; Fu, Tong-Ming; Casimiro, Danilo R; Zhang, Ningyan; A Vora, Kalpit; An, Zhiqiang

2015-01-01

Nonhuman primates (NHPs) are used as a preclinical model for vaccine development, and the antibody profiles to experimental vaccines in NHPs can provide critical information for both vaccine design and translation to clinical efficacy. However, an efficient protocol for generating monoclonal antibodies from single antibody secreting cells of NHPs is currently lacking. In this study we established a robust protocol for cloning immunoglobulin (IG) variable domain genes from single rhesus macaque (Macaca mulatta) antibody secreting cells. A sorting strategy was developed using a panel of molecular markers (CD3, CD19, CD20, surface IgG, intracellular IgG, CD27, Ki67 and CD38) to identify the kinetics of B cell response after vaccination. Specific primers for the rhesus macaque IG genes were designed and validated using cDNA isolated from macaque peripheral blood mononuclear cells. Cloning efficiency was averaged at 90% for variable heavy (VH) and light (VL) domains, and 78.5% of the clones (n = 335) were matched VH and VL pairs. Sequence analysis revealed that diverse IGHV subgroups (for VH) and IGKV and IGLV subgroups (for VL) were represented in the cloned antibodies. The protocol was tested in a study using an experimental dengue vaccine candidate. About 26.6% of the monoclonal antibodies cloned from the vaccinated rhesus macaques react with the dengue vaccine antigens. These results validate the protocol for cloning monoclonal antibodies in response to vaccination from single macaque antibody secreting cells, which have general applicability for determining monoclonal antibody profiles in response to other immunogens or vaccine studies of interest in NHPs.

Antibody mediated in vivo delivery of small interfering RNAs via cell-surface receptors.

PubMed

Song, Erwei; Zhu, Pengcheng; Lee, Sang-Kyung; Chowdhury, Dipanjan; Kussman, Steven; Dykxhoorn, Derek M; Feng, Yi; Palliser, Deborah; Weiner, David B; Shankar, Premlata; Marasco, Wayne A; Lieberman, Judy

2005-06-01

Delivery of small interfering RNAs (siRNAs) into cells is a key obstacle to their therapeutic application. We designed a protamine-antibody fusion protein to deliver siRNA to HIV-infected or envelope-transfected cells. The fusion protein (F105-P) was designed with the protamine coding sequence linked to the C terminus of the heavy chain Fab fragment of an HIV-1 envelope antibody. siRNAs bound to F105-P induced silencing only in cells expressing HIV-1 envelope. Additionally, siRNAs targeted against the HIV-1 capsid gene gag, inhibited HIV replication in hard-to-transfect, HIV-infected primary T cells. Intratumoral or intravenous injection of F105-P-complexed siRNAs into mice targeted HIV envelope-expressing B16 melanoma cells, but not normal tissue or envelope-negative B16 cells; injection of F105-P with siRNAs targeting c-myc, MDM2 and VEGF inhibited envelope-expressing subcutaneous B16 tumors. Furthermore, an ErbB2 single-chain antibody fused with protamine delivered siRNAs specifically into ErbB2-expressing cancer cells. This study demonstrates the potential for systemic, cell-type specific, antibody-mediated siRNA delivery.

Dendritic cells and follicular dendritic cells express a novel ligand for CD38 which influences their maturation and antibody responses

PubMed Central

Wykes, Michelle N; Beattie, Lynette; MacPherson, Gordon G; Hart, Derek N

2004-01-01

CD38 is a cell surface molecule with ADP-ribosyl cyclase activity, which is predominantly expressed on lymphoid and myeloid cells. CD38 has a significant role in B-cell function as some anti-CD38 antibodies can deliver potent growth and differentiation signals, but the ligand that delivers this signal in mice is unknown. We used a chimeric protein of mouse CD38 and human immunogobulin G (IgG) (CD38-Ig) to identify a novel ligand for murine CD38 (CD38L) on networks of follicular dendritic cells (FDCs) as well as dendritic cells (DCs) in the spleen. Flow-cytometry found that all DC subsets expressed cytoplasmic CD38L but only fresh ex vivo CD11c+ CD11b− DCs had cell surface CD38L. Anti-CD38 antibody blocked the binding of CD38-Ig to CD38L, confirming the specificity of detection. CD38-Ig immuno-precipitated ligands of 66 and 130 kDa. Functional studies found that CD38-Ig along with anti-CD40 and anti-major histocompatibility complex (MHC) class II antibody provided maturation signals to DCs in vitro. When CD38-Ig was administered in vivo with antigen, IgG2a responses were significantly reduced, suggesting that B and T cells expressing CD38 may modulate the isotype of antibodies produced through interaction with CD38L on DCs. CD38-Ig also expanded FDC networks when administered in vivo. In conclusion, this study has identified a novel ligand for CD38 which has a role in functional interactions between lymphocytes and DCs or FDCs. PMID:15500618

Dendritic cells and follicular dendritic cells express a novel ligand for CD38 which influences their maturation and antibody responses.

PubMed

Wykes, Michelle N; Beattie, Lynette; Macpherson, Gordon G; Hart, Derek N

2004-11-01

CD38 is a cell surface molecule with ADP-ribosyl cyclase activity, which is predominantly expressed on lymphoid and myeloid cells. CD38 has a significant role in B-cell function as some anti-CD38 antibodies can deliver potent growth and differentiation signals, but the ligand that delivers this signal in mice is unknown. We used a chimeric protein of mouse CD38 and human immunogobulin G (IgG) (CD38-Ig) to identify a novel ligand for murine CD38 (CD38L) on networks of follicular dendritic cells (FDCs) as well as dendritic cells (DCs) in the spleen. Flow-cytometry found that all DC subsets expressed cytoplasmic CD38L but only fresh ex vivo CD11c+ CD11b- DCs had cell surface CD38L. Anti-CD38 antibody blocked the binding of CD38-Ig to CD38L, confirming the specificity of detection. CD38-Ig immuno-precipitated ligands of 66 and 130 kDa. Functional studies found that CD38-Ig along with anti-CD40 and anti-major histocompatibility complex (MHC) class II antibody provided maturation signals to DCs in vitro. When CD38-Ig was administered in vivo with antigen, IgG2a responses were significantly reduced, suggesting that B and T cells expressing CD38 may modulate the isotype of antibodies produced through interaction with CD38L on DCs. CD38-Ig also expanded FDC networks when administered in vivo. In conclusion, this study has identified a novel ligand for CD38 which has a role in functional interactions between lymphocytes and DCs or FDCs.

Development of Antibodies Against Novel Cell Surface Proteins In Hormone Refractory Prostate Cancer. Addendum

DTIC Science & Technology

2011-07-01

marker of hormone refractory metastatic prostate cancer. Clin Cancer Res, 2005. 15: 2237- 43 . 3. Tomita K, van Bokhoven A, van Leenders GJ, Ruijter...Santa Cruz Biotechnology), vimentin, Ki-67 (DakoCytomation) and caspase-3 (Cell Signaling Technology). Flow cytometry was performed with N...transduced cells were labeled with N-cadherin–specific antibody and sorted by flow cytometry , gating for a GFP-positive, N-cadherinlow population. The

Foot-and-Mouth Disease Virus Can Induce a Specific and Rapid CD4+ T-Cell-Independent Neutralizing and Isotype Class-Switched Antibody Response in Naïve Cattle▿ †

PubMed Central

Juleff, Nicholas; Windsor, Miriam; Lefevre, Eric A.; Gubbins, Simon; Hamblin, Pip; Reid, Elizabeth; McLaughlin, Kerry; Beverley, Peter C. L.; Morrison, Ivan W.; Charleston, Bryan

2009-01-01

The role of T-lymphocyte subsets in recovery from foot-and-mouth disease virus (FMDV) infection in calves was investigated by administering subset-specific monoclonal antibodies. The depletion of circulating CD4+ or WC1+ γδ T cells was achieved for a period extending from before challenge to after resolution of viremia and peak clinical signs, whereas CD8+ cell depletion was only partial. The depletion of CD4+ cells was also confirmed by analysis of lymph node biopsy specimens 5 days postchallenge. Depletion with anti-WC1 and anti-CD8 antibodies had no effect on the kinetics of infection, clinical signs, and immune responses following FMDV infection. Three of the four CD4+ T-cell-depleted calves failed to generate an antibody response to the nonstructural polyprotein 3ABC but generated a neutralizing antibody response similar to that in the controls, including rapid isotype switching to immunoglobulin G antibody. We conclude that antibody responses to sites on the surface of the virus capsid are T cell independent, whereas those directed against the nonstructural proteins are T cell dependent. CD4 depletion was found to substantially inhibit antibody responses to the G-H peptide loop VP1135-156 on the viral capsid, indicating that responses to this particular site, which has a more mobile structure than other neutralizing sites on the virus capsid, are T cell dependent. The depletion of CD4+ T cells had no adverse effect on the magnitude or duration of clinical signs or clearance of virus from the circulation. Overall, we conclude that CD4+ T-cell-independent antibody responses play a major role in the resolution of foot-and-mouth disease in cattle. PMID:19176618

Charge heterogeneity: Basic antibody charge variants with increased binding to Fc receptors.

PubMed

Hintersteiner, Beate; Lingg, Nico; Zhang, Peiqing; Woen, Susanto; Hoi, Kong Meng; Stranner, Stefan; Wiederkum, Susanne; Mutschlechner, Oliver; Schuster, Manfred; Loibner, Hans; Jungbauer, Alois

We identified active isoforms of the chimeric anti-GD2 antibody, ch14.18, a recombinant antibody produced in Chinese hamster ovary cells, which is already used in clinical trials. 1,2,3 We separated the antibody by high resolution ion-exchange chromatography with linear pH gradient elution into acidic, main and basic charge variants on a preparative scale yielding enough material for an in-depth study of the sources and the effects of microheterogeneity. The binding affinity of the charge variants toward the antigen and various cell surface receptors was studied by Biacore. Effector functions were evaluated using cellular assays for antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. Basic charge variants showed increased binding to cell surface receptor FcγRIIIa, which plays a major role in regulating effector functions. Furthermore, increased binding of the basic fractions to the neonatal receptor was observed. As this receptor mediates the prolonged half-life of IgG in human serum, this data may well hint at an increased serum half-life of these basic variants compared to their more acidic counterparts. Different glycoform patterns, C-terminal lysine clipping and N-terminal pyroglutamate formation were identified as the main structural sources for the observed isoform pattern. Potential differences in structural stability between individual charge variant fractions by nano differential scanning calorimetry could not been detected. Our in-vitro data suggests that the connection between microheterogeneity and the biological activity of recombinant antibody therapeutics deserves more attention than commonly accepted.

Anti-LRP/LR Specific Antibody IgG1-iS18 Impedes Adhesion and Invasion of Liver Cancer Cells

PubMed Central

Chetty, Carryn; Khumalo, Thandokuhle; Da Costa Dias, Bianca; Reusch, Uwe; Knackmuss, Stefan; Little, Melvyn; Weiss, Stefan F. T.

2014-01-01

Two key events, namely adhesion and invasion, are pivotal to the occurrence of metastasis. Importantly, the 37 kDa/67 kDa laminin receptor (LRP/LR) has been implicated in enhancing these two events thus facilitating cancer progression. In the current study, the role of LRP/LR in the adhesion and invasion of liver cancer (HUH-7) and leukaemia (K562) cells was investigated. Flow cytometry revealed that the HUH-7 cells displayed significantly higher cell surface LRP/LR levels compared to the poorly-invasive breast cancer (MCF-7) control cells, whilst the K562 cells displayed significantly lower cell surface LRP/LR levels in comparison to the MCF-7 control cells. However, Western blotting and densitometric analysis revealed that all three tumorigenic cell lines did not differ significantly with regards to total LRP/LR levels. Furthermore, treatment of liver cancer cells with anti-LRP/LR specific antibody IgG1-iS18 (0.2 mg/ml) significantly reduced the adhesive potential of cells to laminin-1 and the invasive potential of cells through the ECM-like Matrigel, whilst leukaemia cells showed no significant differences in both instances. Additionally, Pearson's correlation coefficients suggested direct proportionality between cell surface LRP/LR levels and the adhesive and invasive potential of liver cancer and leukaemia cells. These findings suggest the potential use of anti-LRP/LR specific antibody IgG1-iS18 as an alternative therapeutic tool for metastatic liver cancer through impediment of the LRP/LR- laminin-1 interaction. PMID:24798101

Anti-CD30-targeted gold nanoparticles for photothermal therapy of L-428 Hodgkin’s cell

PubMed Central

Qu, Xiaochao; Yao, Cuiping; Wang, Jing; Li, Zheng; Zhang, Zhenxi

2012-01-01

Purpose Due to the efficient bioconjugation and highly photothermal effect, gold nanoparticles can stain receptor-overexpressing cancer cells through specific targeting of ligands to receptors, strongly absorb specific light and efficiently convert it into heat based on the property of surface plasmon resonance, and then induce the localized protein denaturation and cell death. Methods Two gold nanoparticle–antibody conjugates, gold-BerH2 antibody (anti-CD30 receptor) and gold-ACT1 antibody (anti-CD25-receptor), were synthesized. Gold-BerH2 conjugates can specifically bind to the surface of L-428 Hodgkin’s cells, and gold-ACT1 conjugates were used for the control. The gold nanoparticle-induced L-428 cell-killing experiments were implemented with different experimental parameters. Results At a relatively low concentration of gold and short incubation time, the influence of cytotoxicity of gold on cell viability can be overlooked. Under laser irradiation at suitable power, the high killing efficiency of gold-targeted L-428 cells was achieved, but little damage was done to nontargeted cancer cells. Conclusion Gold nanoparticle-mediated photothermal therapy provides a relatively safe therapeutic technique for cancer treatment. PMID:23269868

When No Response Is a Good Thing | Center for Cancer Research

Cancer.gov

Custom-designed therapies that target cell-surface antigens or receptors represent a promising immunological approach in cancer therapy. Antibodies that bind these targets are the starting point.  Potent toxins can then be added to them by fusing antibody fragments to powerful bacterial toxins such as Pseudomonas exotoxin (PE). This recombinant immunotoxin combines antibody

Cancer cell uptake behavior of Au nanoring and its localized surface plasmon resonance induced cell inactivation

NASA Astrophysics Data System (ADS)

Chu, Che-Kuan; Tu, Yi-Chou; Chang, Yu-Wei; Chu, Chih-Ken; Chen, Shih-Yang; Chi, Ting-Ta; Kiang, Yean-Woei; Yang, Chih-Chung

2015-02-01

Au nanorings (NRIs), which have the localized surface plasmon resonance (LSPR) wavelength around 1058 nm, either with or without linked antibodies, are applied to SAS oral cancer cells for cell inactivation through the LSPR-induced photothermal effect when they are illuminated by a laser of 1065 nm in wavelength. Different incubation times of cells with Au NRIs are considered for observing the variations of cell uptake efficiency of Au NRI and the threshold laser intensity for cell inactivation. In each case of incubation time, the cell sample is washed for evaluating the total Au NRI number per cell adsorbed and internalized by the cells based on inductively coupled plasma mass spectrometry measurement. Also, the Au NRIs remaining on cell membrane are etched with KI/I2 solution to evaluate the internalized Au NRI number per cell. The threshold laser intensities for cell inactivation before washout, after washout, and after KI/I2 etching are calibrated from the circular area sizes of inactivated cells around the illuminated laser spot center with various laser power levels. By using Au NRIs with antibodies, the internalized Au NRI number per cell increases monotonically with incubation time up to 24 h. However, the number of Au NRI remaining on cell membrane reaches a maximum at 12 h in incubation time. The cell uptake behavior of an Au NRI without antibodies is similar to that with antibodies except that the uptake NRI number is significantly smaller and the incubation time for the maximum NRI number remaining on cell membrane is delayed to 20 h. By comparing the threshold laser intensities before and after KI/I2 etching, it is found that the Au NRIs remaining on cell membrane cause more effective cancer cell inactivation, when compared with the internalized Au NRIs.

Dendritic Cell-Based Genetic Immunotherapy for Ovarian Cancer

DTIC Science & Technology

2008-12-01

transduction of dendritic cells (DCs) is inefficient because of the lack of the primary Ad receptor, CAR. CD40 is a surface marker expressed by DCs that...ligands or antibodies that can bind to the cell surface markers expressed by DCs. The tumor antigen or peptides are linked to the ligands...thus pose the risk of insertional mutagenesis and oncogenesis. The various cell- surface markers that have been exploited for targeting DCs have

A view of the E2-CD81 interface at the binding site of a neutralizing antibody against hepatitis C virus.

PubMed

Harman, Christine; Zhong, Lilin; Ma, Li; Liu, Peter; Deng, Lu; Zhao, Zhong; Yan, Hailing; Struble, Evi; Virata-Theimer, Maria Luisa; Zhang, Pei

2015-01-01

Hepatitis C virus (HCV) glycoprotein E2 is considered a major target for generating neutralizing antibodies against HCV, primarily due to its role of engaging host entry factors, such as CD81, a key cell surface protein associated with HCV entry. Based on a series of biochemical analyses in combination with molecular docking, we present a description of a potential binding interface formed between the E2 protein and CD81. The virus side of this interface includes a hydrophobic helix motif comprised of residues W(437)LAGLF(442), which encompasses the binding site of a neutralizing monoclonal antibody, mAb41. The helical conformation of this motif provides a structural framework for the positioning of residues F442 and Y443, serving as contact points for the interaction with CD81. The cell side of this interface likewise involves a surface-exposed hydrophobic helix, namely, the D-helix of CD81, which coincides with the binding site of 1D6, a monoclonal anti-CD81 antibody known to block HCV entry. Our illustration of this virus-host interface suggests an important role played by the W(437)LAGLF(442) helix of the E2 protein in the hydrophobic interaction with the D-helix of CD81, thereby facilitating our understanding of the mechanism for antibody-mediated neutralization of HCV. Characterization of the interface established between a virus and host cells can provide important information that may be used for the control of virus infections. The interface that enables hepatitis C virus (HCV) to infect human liver cells has not been well understood because of the number of cell surface proteins, factors, and conditions found to be associated with the infection process. Based on a series of biochemical analyses in combination with molecular docking, we present such an interface, consisting of two hydrophobic helical structures, from the HCV E2 surface glycoprotein and the CD81 protein, a major host cell receptor recognized by all HCV strains. Our study reveals the critical role played by hydrophobic interactions in the formation of this virus-host interface, thereby contributing to our understanding of the mechanism for antibody-mediated neutralization of HCV. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

77 FR 41408 - Agency Information Collection Activities; Submission for Office of Management and Budget Review...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-13

... protocols for specific licensed biological products: Sec. Sec. 660.6 (21 CFR 660.6) (Antibody to Hepatitis B Surface Antigen); 660.36 (21 CFR 660.36) (Reagent Red Blood Cells); and 660.46 (21 CFR 660.46) (Hepatitis... samples from each lot of Antibody to Hepatitis B Surface Antigen product, and Sec. 660.6(b) provides the...

On-Orbit, Immuno-Based, Label-Free White Blood Cell Counting System with Microelectromechanical Sensor Technology (OILWBCS-MEMS)

NASA Technical Reports Server (NTRS)

Edmonds, Jessica

2015-01-01

Aurora Flight Sciences, in partnership with Draper Laboratory, has developed a miniaturized system to count white blood cells in microgravity environments. The system uses MEMS technology to simultaneously count total white blood cells, the five white blood cell differential subgroups, and various lymphocyte subtypes. The OILWBCS-MEMS detection technology works by immobilizing an array of white blood cell-specific antibodies on small, gold-coated membranes. When blood flows across the membranes, specific cells' surface protein antigens bind to their corresponding antibodies. This binding can be measured and correlated to cell counts. In Phase I, the partners demonstrated surface chemistry sensitivity and specificity for total white blood cells and two lymphocyte subtypes. In Phase II, a functional prototype demonstrated end-to-end operation. This rugged, miniaturized device requires minimal blood sample preparation and will be useful for both space flight and terrestrial applications.

In vivo analysis of replication and immunogenicity of proviral clones of human T-lymphotropic virus type 1 with selective envelope surface-unit mutations

PubMed Central

Silverman, Lee R.; Phipps, Andrew J.; Montgomery, Andy; Fernandez, Soledad; Tsukahara, Tomonori; Ratner, Lee; Lairmore, Michael D.

2005-01-01

Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell lymphoma/leukemia (ATL). The HTLV-1 envelope gene exhibits limited variability when examined from infected individuals, but has not been tested using infectious clones of the virus in animal models. In vitro assays indicate that HTLV-1 envelope (Env) Ser75Ile, Asn95Asp, and Asn195Asp surface unit (SU) mutants are able to replicate in and immortalize lymphocytes. Herein, we examined the effects of these Env mutants in rabbits inoculated with HTLV-1 immortalized ACH.75, ACH.95, or ACH.195 cell lines (expressing full-length molecular clones with the SU mutations) or the ACH.1 cell line (expressing wild-type SU). All rabbits became infected, and the fidelity of the mutations was maintained throughout the 8-week study. However, SU point mutations resulted in decreased antibody responses to viral group-associated antigen (Gag) and Env antigens. ACH.195 rabbits had a selective decreased antibody response to SU, and one ACH.195 rabbit had an antibody response to both HTLV-1 and HTLV-2 SUs. Some mutant inoculation groups had altered proviral loads. However, peripheral-blood mononuclear cell (PBMC) proviral loads did not correlate with antibody responses. Our data are the first to demonstrate that mutations in critical determinants of HTLV-1 Env SU altered antibody responses and proviral loads, but do not prevent viral replication in vivo. PMID:16046523

Development of a new high-affinity human antibody with antitumor activity against solid and blood malignancies.

PubMed

Sioud, Mouldy; Westby, Phuong; Vasovic, Vlada; Fløisand, Yngvar; Peng, Qian

2018-04-16

mAbs have emerged as a promising strategy for the treatment of cancer. However, in several malignancies, no effective antitumor mAbs are yet available. Identifying therapeutic mAbs that recognize common tumor antigens could render the treatment widely applicable. Here, a human single-chain variable fragment (scFv) antibody library was sequentially affinity selected against a panel of human cancer cell lines and an antibody fragment (named MS5) that bound to solid and blood cancer cells was identified. The MS5 scFv was fused to the human IgG1 Fc domain to generate an antibody (MS5-Fc fusion) that induced antibody-dependent cellular cytotoxicity and phagocytosis of cancer cells by macrophages. In addition, the MS5-Fc antibody bound to primary leukemia cells and induced antibody-dependent cellular cytotoxicity. In the majority of analyzed cancer cells, the MS5-Fc antibody induced cell surface redistribution of the receptor complexes, but not internalization, thus maximizing the accessibility of the IgG1 Fc domain to immune effector cells. In vitro stability studies showed that the MS5-Fc antibody was stable after 6 d of incubation in human serum, retaining ∼60% of its initial intact form. After intravenous injections, the antibody localized into tumor tissues and inhibited the growth of 3 different human tumor xenografts (breast, lymphoma, and leukemia). These antitumor effects were associated with tumor infiltration by macrophages and NK cells. In the Ramos B-cell lymphoma xenograft model, the MS5-Fc antibody exhibited a comparable antitumor effect as rituximab, a chimeric anti-CD20 IgG1 mAb. These results indicate that human antibodies with pan-cancer abilities can be generated from phage display libraries, and that the engineered MS5-Fc antibody could be an attractive agent for further clinical investigation.-Sioud, M., Westby, P., Vasovic, V., Fløisand, Y., Peng, Q. Development of a new high-affinity human antibody with antitumor activity against solid and blood malignancies.

Intracellular distribution of TM4SF1 and internalization of TM4SF1-antibody complex in vascular endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sciuto, Tracey E.; Merley, Anne; Lin, Chi-Iou

2015-09-25

Transmembrane-4 L-six family member-1 (TM4SF1) is a small plasma membrane-associated glycoprotein that is highly and selectively expressed on the plasma membranes of tumor cells, cultured endothelial cells, and, in vivo, on tumor-associated endothelium. Immunofluorescence microscopy also demonstrated TM4SF1 in cytoplasm and, tentatively, within nuclei. With monoclonal antibody 8G4, and the finer resolution afforded by immuno-nanogold transmission electron microscopy, we now demonstrate TM4SF1 in uncoated cytoplasmic vesicles, nuclear pores and nucleoplasm. Because of its prominent surface location on tumor cells and tumor-associated endothelium, TM4SF1 has potential as a dual therapeutic target using an antibody drug conjugate (ADC) approach. For ADC to bemore » successful, antibodies reacting with cell surface antigens must be internalized for delivery of associated toxins to intracellular targets. We now report that 8G4 is efficiently taken up into cultured endothelial cells by uncoated vesicles in a dynamin-dependent, clathrin-independent manner. It is then transported along microtubules through the cytoplasm and passes through nuclear pores into the nucleus. These findings validate TM4SF1 as an attractive candidate for cancer therapy with antibody-bound toxins that have the capacity to react with either cytoplasmic or nuclear targets in tumor cells or tumor-associated vascular endothelium. - Highlights: • Anti-TM4SF1 antibody 8G4 was efficiently taken up by cultured endothelial cells. • TM4SF1–8G4 internalization is dynamin-dependent but clathrin-independent. • TM4SF1–8G4 complexes internalize along microtubules to reach the perinuclear region. • Internalized TM4SF1–8G4 complexes pass through nuclear pores into the nucleus. • TM4SF1 is an attractive candidate for ADC cancer therapy.« less

Impact of Diverse Immune Evasion Mechanisms of Cancer Cells on T Cells Engaged by EpCAM/CD3-Bispecific Antibody Construct AMG 110

PubMed Central

Deisting, Wibke; Raum, Tobias; Kufer, Peter; Baeuerle, Patrick A.; Münz, Markus

2015-01-01

Background Bispecific T cell engager (BiTE®) are single-chain bispecific antibody constructs with dual specificity for CD3 on T cells and a surface antigen on target cells. They can elicit a polyclonal cytotoxic T cell response that is not restricted by T cell receptor (TCR) specificity, and surface expression of MHC class I/peptide antigen complexes. Using human EpCAM/CD3-bispecific BiTE® antibody construct AMG 110, we here assessed to what extent surface expression of PD-L1, cytoplasmic expression of indoleamine-2,3-deoxygenase type 1, Bcl-2 and serpin PI-9, and the presence of transforming growth factor beta (TGF-β), interleukin-10 (IL-10) and adenosine in culture medium can impact redirected lysis by AMG 110-engaged T cells. Methods The seven factors, which are all involved in inhibiting T cell functions by cancer cells, were tested with human EpCAM-expressing Chinese hamster ovary (CHO) target cells at levels that in most cases exceeded those observed in a number of human cancer cell lines. Co-culture experiments were used to determine the impact of the evasion mechanisms on EC50 values and amplitude of redirected lysis by AMG 110, and on BiTE®-induced proliferation of previously resting human peripheral T cells. Findings An inhibitory effect on redirected lysis by AMG 110-engaged T cells was seen upon overexpression of serpin PI-9, Bcl-2, TGF-βand PD-L1. An inhibitory effect on induction of T cell proliferation was only seen with CHO cells overexpressing IDO. In no case, a single evasion mechanism rendered target cells completely resistant to BiTE®-induced lysis, and even various combinations could not. Conclusions Our data suggest that diverse mechanisms employed by cancer cells to fend off T cells cannot inactivate AMG 110-engaged T cells, and that inhibitory effects observed in vitro may be overcome by increased concentrations of the BiTE® antibody construct. PMID:26510188

Immunohistochemistry of the lymphoid tissues of the tammar wallaby, Macropus eugenii

PubMed Central

Old, Julie M; Deane, Elizabeth M

2002-01-01

The lymphoid tissues of the metatherian mammal, the adult tammar wallaby, Macropus eugenii, were investigated using immunohistochemical techniques. Five cross-reactive antibodies previously shown to recognize surface markers in marsupial tissues and five previously untested antibodies were used. The distribution of T-cells in the tissue beds of spleen, lymph node, thymus, gut-associated lymphoid tissue (GALT) and bronchus-associated lymphoid tissue (BALT) was documented using antibodies to CD3 and CD5. Similarly, B-cells were identified in the same tissues using anti-CD79b. Antibodies to CD8, CD31, CD79a and CD68 failed to recognize cells in these tissue beds. In general the pattern of cellular distribution identified using these antibodies was similar to that observed in other marsupial and eutherian lymphoid tissues. This study provides further information on the commonality of lymphoid tissue structure in the two major groups of extant mammals, metatherians and eutherians. PMID:12363276

Pernicious anemia and juvenile-onset diabetes mellitus in an adolescent: a case report.

PubMed

Yu, L C; Warrier, R P; Ducos, R S

1989-02-01

We report a case of a 15-year-old black boy who developed juvenile-onset pernicious anemia in association with insulin-dependent diabetes mellitus. He had both intrinsic factor and parietal cell antibodies in addition to anti-islet cell surface antibodies. The existence of pernicious anemia and diabetes mellitus in such a young child makes this an unusual case.

Expression of bovine non-classical major histocompatibility complex class 1 proteins in mouse P815 and human K562 cells

USDA-ARS?s Scientific Manuscript database

Major histocompatibility complex class I (MHC-I) proteins can be expressed as cell surface or secreted proteins. To investigate whether bovine non-classical MHC-I proteins are expressed as cell surface or secreted proteins, and to assess the reactivity pattern of monoclonal antibodies with non-class...

Recombinant immunotoxins and retargeted killer cells: employing engineered antibody fragments for tumor-specific targeting of cytotoxic effectors.

PubMed

Wels, Winfried; Biburger, Markus; Müller, Tina; Dälken, Benjamin; Giesübel, Ulrike; Tonn, Torsten; Uherek, Christoph

2004-03-01

Over the past years, monoclonal antibodies have attracted enormous interest as targeted therapeutics, and a number of such reagents are in clinical use. However, responses could not be achieved in all patients with tumors expressing high levels of the respective target antigens, suggesting that other factors such as limited recruitment of endogenous immune effector mechanisms can also influence treatment outcome. This justifies the search for alternative, potentially more effective reagents. Antibody-toxins and cytolytic effector cells genetically modified to carry antibody-based receptors on the surface, represent such tailor-made targeting vehicles with the potential of improved tumor localization and enhanced efficacy. In this way, advances in recombinant antibody technology have made it possible to circumvent problems inherent in chemical coupling of antibodies and toxins, and have allowed construction via gene fusion of recombinant molecules which combine antibody-mediated recognition of tumor cells with specific delivery of potent protein toxins of bacterial or plant origin. Likewise, recombinant antibody fragments provide the basis for the construction of chimeric antigen receptors that, upon expression in cytotoxic T lymphocytes (CTLs) or natural killer (NK) cells, link antibody-mediated recognition of tumor antigens with these effector cells' potent cytolytic activities, thereby making them promising cellular therapeutics for adoptive cancer therapy. Here, general principles for the derivation of cytotoxic proteins and effector cells with antibody-dependent tumor specificity are summarized, and current strategies to employ these molecules and cells for directed cancer therapy are discussed, focusing mainly on the tumor-associated antigens epidermal growth factor receptor (EGFR) and the closely related ErbB2 (HER2) as targets.

Detachment strength of human osteoblasts cultured on hydroxyapatite with various surface roughness. Contribution of integrin subunits.

PubMed

Kokkinos, Petros A; Koutsoukos, Petros G; Deligianni, Despina D

2012-06-01

Hydroxyapatite (HA) has been widely used as a bone substitute in dental, maxillofacial and orthopaedic surgery and as osteoconductive bone substitute or precoating of pedicle screws and cages in spine surgery. The aim of the present study was to investigate the osteoblastic adhesion strength on HA substrata with different surface topography and biochemistry (pre-adsorption of fibronectin) after blocking of specific integrin subunits with monoclonal antibodies. Stoichiometric HA was prepared by precipitation followed by ageing and characterized by SEM, EDX, powder XRD, Raman spectroscopy, TGA, and specific surface area analysis. Human bone marrow derived osteoblasts were cultured on HA disc-shaped substrata which were sintered and polished resulting in two surface roughness grades. For attachment evaluation, cells were incubated with monoclonal antibodies and seeded for 2 h on the substrata. Cell detachment strength was determined using a rotating disc device. Cell detachment strength was surface roughness, fibronectin preadsorption and intergin subunit sensitive.

Fluorogenic Cell-Based Biosensors for Monitoring Microbes

NASA Technical Reports Server (NTRS)

Curtis, Theresa; Salazar, Noe; Tabb, Joel; Chase, Chris

2010-01-01

Fluorogenic cell-based sensor systems for detecting microbes (especially pathogenic ones) and some toxins and allergens are undergoing development. These systems harness the natural signaltransduction and amplification cascades that occur in mast cells upon activation with antigens. These systems include (1) fluidic biochips for automated containment of samples, reagents, and wastes and (2) sensitive, compact fluorometers for monitoring the fluorescent responses of mast cells engineered to contain fluorescent dyes. It should be possible to observe responses within minutes of adding immune complexes. The systems have been shown to work when utilizing either immunoglobulin E (IgE) antibodies or traditionally generated rat antibodies - a promising result in that it indicates that the systems could be developed to detect many target microbes. Chimeric IgE antibodies and rat immunoglobulin G (IgG) antibodies could be genetically engineered for recognizing biological and chemical warfare agents and airborne and food-borne allergens. Genetic engineering efforts thus far have yielded (1) CD14 chimeric antibodies that recognize both Grampositive and Gram-negative bacteria and bind to the surfaces of mast cells, eliciting a degranulation response and (2) rat IgG2a antibodies that act similarly in response to low levels of canine parvovirus.

CD4 mimetics sensitize HIV-1-infected cells to ADCC.

PubMed

Richard, Jonathan; Veillette, Maxime; Brassard, Nathalie; Iyer, Shilpa S; Roger, Michel; Martin, Loïc; Pazgier, Marzena; Schön, Arne; Freire, Ernesto; Routy, Jean-Pierre; Smith, Amos B; Park, Jongwoo; Jones, David M; Courter, Joel R; Melillo, Bruno N; Kaufmann, Daniel E; Hahn, Beatrice H; Permar, Sallie R; Haynes, Barton F; Madani, Navid; Sodroski, Joseph G; Finzi, Andrés

2015-05-19

HIV-1-infected cells presenting envelope glycoproteins (Env) in the CD4-bound conformation on their surface are preferentially targeted by antibody-dependent cell-mediated cytotoxicity (ADCC). HIV-1 has evolved a sophisticated mechanism to avoid exposure of ADCC-mediating Env epitopes by down-regulating CD4 and by limiting the overall amount of Env at the cell surface. Here we report that small-molecule CD4-mimetic compounds induce the CD4-bound conformation of Env, and thereby sensitize cells infected with primary HIV-1 isolates to ADCC mediated by antibodies present in sera, cervicovaginal lavages, and breast milk from HIV-1-infected individuals. Importantly, we identified one CD4 mimetic with the capacity to sensitize endogenously infected ex vivo-amplified primary CD4 T cells to ADCC killing mediated by autologous sera and effector cells. Thus, CD4 mimetics hold the promise of therapeutic utility in preventing and controlling HIV-1 infection.

CD4 mimetics sensitize HIV-1-infected cells to ADCC

PubMed Central

Richard, Jonathan; Veillette, Maxime; Brassard, Nathalie; Iyer, Shilpa S.; Roger, Michel; Martin, Loïc; Pazgier, Marzena; Schön, Arne; Freire, Ernesto; Routy, Jean-Pierre; Smith, Amos B.; Park, Jongwoo; Jones, David M.; Courter, Joel R.; Melillo, Bruno N.; Kaufmann, Daniel E.; Hahn, Beatrice H.; Permar, Sallie R.; Haynes, Barton F.; Madani, Navid; Sodroski, Joseph G.; Finzi, Andrés

2015-01-01

HIV-1-infected cells presenting envelope glycoproteins (Env) in the CD4-bound conformation on their surface are preferentially targeted by antibody-dependent cell-mediated cytotoxicity (ADCC). HIV-1 has evolved a sophisticated mechanism to avoid exposure of ADCC-mediating Env epitopes by down-regulating CD4 and by limiting the overall amount of Env at the cell surface. Here we report that small-molecule CD4-mimetic compounds induce the CD4-bound conformation of Env, and thereby sensitize cells infected with primary HIV-1 isolates to ADCC mediated by antibodies present in sera, cervicovaginal lavages, and breast milk from HIV-1-infected individuals. Importantly, we identified one CD4 mimetic with the capacity to sensitize endogenously infected ex vivo-amplified primary CD4 T cells to ADCC killing mediated by autologous sera and effector cells. Thus, CD4 mimetics hold the promise of therapeutic utility in preventing and controlling HIV-1 infection. PMID:25941367

Detection of cell surface calreticulin as a potential cancer biomarker using near-infrared emitting gold nanoclusters

NASA Astrophysics Data System (ADS)

Subramaniyam Ramesh, Bala; Giorgakis, Emmanouil; Lopez-Davila, Victor; Kamali Dashtarzheneha, Ashkan; Loizidou, Marilena

2016-07-01

Calreticulin (CRT) is a cytoplasmic calcium-binding protein. The aim of this study was to investigate CRT presence in cancer with the use of fluorescent gold nanoclusters (AuNCs) and to explore AuNC synthesis using mercaptosuccinic acid (MSA) as a coating agent. MSA-coated AuNCs conferred well-dispersed, bio-stable, water-soluble nanoparticles with bioconjugation capacity and 800-850 nm fluorescence after broad-band excitation. Cell-viability assay revealed good AuNC tolerability. A native CRT amino-terminus corresponding peptide sequence was synthesised and used to generate rabbit site-specific antibodies. Target specificity was demonstrated with antibody blocking in colorectal and breast cancer cell models; human umbilical vein endothelial cells served as controls. We demonstrated a novel route of AuNC/MSA manufacture and CRT presence on colonic and breast cancerous cell surface. AuNCs served as fluorescent bio-probes specifically recognising surface-bound CRT. These results are promising in terms of AuNC application in cancer theranostics and CRT use as surface biomarker in human cancer.

[Autoimmune Encephalitis Associated with Malignant Tumors].

PubMed

Inuzuka, Takashi

2016-09-01

Autoimmune encephalitis consists of limbic symptoms and signs associated with antibodies against neuronal cell-surface antigens or intracellular antigens. Some cases are known to be associated with anti-channel or anti-receptor-related molecule antibodies. Whether these cases are paraneoplastic depends on the kinds of antigens that the antibodies are produced against. Other cases due to well-characterized onco-neural antibodies are almost always paraneoplastic and are generally resistant to anti-tumor therapy and/or immunotherapy. An exception is anti-Ma2 antibody-positive encephalitis associated with a testicular tumor. Antibodies for intracellular antigens are considered not to be pathogenic. Rather, the T-cell response is thought to be responsible. These antibodies are useful markers for the diagnosis of paraneoplastic disorders and in the search for underlying cancer, as neurological symptoms often precede tumor diagnosis. There is a relationship among onco-neural antibodies, clinical features, tumor types, and response to immunotherapy. Here we describe the characteristics of autoimmune encephalitis cases with antibodies against different intracellular antigens, such as Hu, Ma2, CRMP5, or amphiphysin.

A Spectrum of Monoclonal Antibodies Reactive with Human Mammary Tumor Cells

NASA Astrophysics Data System (ADS)

Colcher, D.; Horan Hand, P.; Nuti, M.; Schlom, J.

1981-05-01

Splenic lymphocytes of mice, immunized with membrane-enriched fractions of metastatic human mammary carcinoma tissues, were fused with the NS-1 non-immunoglobulin-secreting murine myeloma cell line. This resulted in the generation of hybridoma cultures secreting immunoglobulins reactive in solid-phase radioimmunoassays with extracts of metastatic mammary carcinoma cells from involved livers, but not with extracts of apparently normal human liver. As a result of further screening of immunoglobulin reactivities and double cloning of cultures, 11 monoclonal antibodies were chosen that demonstrated reactivities with human mammary tumor cells and not with apparently normal human tissues. These monoclonal antibodies could be placed into at least five major groups on the basis of their differential binding to the surface of various live human mammary tumor cells in culture, to extracts of mammary tumor tissues, or to tissue sections of mammary tumor cells studied by the immunoperoxidase technique. Whereas a spectrum of reactivities to mammary tumors was observed with the 11 monoclonal antibodies, no reactivity was observed to apparently normal cells of the following human tissues: breast, lymph node, lung, skin, testis, kidney, thymus, bone marrow, spleen, uterus, thyroid, intestine, liver, bladder, tonsils, stomach, prostate, and salivary gland. Several of the antibodies also demonstrated a ``pancarcinoma'' reactivity, showing binding to selected non-breast carcinomas. None of the monoclonal antibodies showed binding to purified ferritin or carcinoembryonic antigen. Monoclonal antibodies of all five major groups, however, demonstrated binding to human metastatic mammary carcinoma cells both in axillary lymph nodes and at distal sites.

Biotin-transfer from a trifunctional crosslinker for identification of cell surface receptors of soluble protein ligands

PubMed Central

Tremblay, Tammy-Lynn; Hill, Jennifer J.

2017-01-01

Here we describe a novel crosslinker and its application as a biotin-transfer reagent to identify cell surface receptors of soluble protein ligands on live cells. This crosslinker contains three functional groups: an aldehyde-reactive aminooxy group, a sulfhydryl, and a biotin (ASB). It is readily synthesized via a 3-step addition reaction using standard solid-phase peptide synthesis methods and commercially available intermediates, allowing access to laboratories without specialized synthetic chemistry capabilities. For the biotin-transfer method, ASB is linked to a protein ligand through the sulfhydryl group in a two-step process that allows the introduction of a disulfide bond between the ligand and the crosslinker. Incubation of the labelled ligand with oxidized live cells leads to the formation of crosslinks with aldehyde-containing glycans on the cell surface receptor. Subsequent reduction of the disulfide bond results in biotin transfer from the ligand to the cell surface receptor. Protein biotinylation that is mediated by ligand binding to its receptor is differentiated from background biotinylation events by comparison with a similarly labelled control protein using comparative proteomic mass spectrometry to quantify streptavidin-bound proteins. Using this method, we successfully identified the cell surface receptors of a peptide hormone, a monoclonal antibody, and a single-domain antibody-Fc fusion construct. PMID:28422167

Direct association of thioredoxin-1 (TRX) with macrophage migration inhibitory factor (MIF): regulatory role of TRX on MIF internalization and signaling.

PubMed

Son, Aoi; Kato, Noriko; Horibe, Tomohisa; Matsuo, Yoshiyuki; Mochizuki, Michika; Mitsui, Akira; Kawakami, Koji; Nakamura, Hajime; Yodoi, Junji

2009-10-01

Thioredoxin-1 (TRX) is a small (14 kDa) multifunctional protein with the redox-active site Cys-Gly-Pro-Cys. Macrophage migration inhibitory factor (MIF) is a 12 kDa cytokine belonging to the TRX family. Historically, when we purified TRX from the supernatant of ATL-2 cells, a 12 kDa protein was identified along with TRX, which was later proved to be MIF. Here, we show that TRX and MIF form a complex in the cell and the culture supernatant of ATL-2 cells. Using a BIAcore assay, we confirmed that TRX has a specific affinity with MIF. We also found that extracellular MIF was more effectively internalized into the ATL-2 cells expressing TRX on the cell surface, than the Jurkat T cells which do not express surface TRX. Moreover, anti-TRX antibody blocked the MIF internalization, suggesting that the cell surface TRX is involved in MIF internalization into the cells. Furthermore, anti-TRX antibody inhibited MIF-mediated enhancement of TNF-alpha production from macrophage RAW264.7 cells. These results suggest that the cell surface TRX serves as one of the MIF binding molecules or MIF receptor component and inhibits MIF-mediated inflammatory signals.

Regulatory CD4 T cells inhibit HIV-1 expression of other CD4 T cell subsets via interactions with cell surface regulatory proteins.

PubMed

Zhang, Mingce; Robinson, Tanya O; Duverger, Alexandra; Kutsch, Olaf; Heath, Sonya L; Cron, Randy Q

2018-03-01

During chronic HIV-1 infection, regulatory CD4 T cells (Tregs) frequently represent the largest subpopulation of CD4 T cell subsets, implying relative resistant to HIV-1. When HIV-1 infection of CD4 T cells was explored in vitro and ex vivo from patient samples, Tregs possessed lower levels of HIV-1 DNA and RNA in comparison with conventional effector and memory CD4 T cells. Moreover, Tregs suppressed HIV-1 expression in other CD4 T cells in an in vitro co-culture system. This suppression was mediated in part via multiple inhibitory surface proteins expressed on Tregs. Antibody blockade of CTLA-4, PD-1, and GARP on Tregs resulted in increased HIV-1 DNA integration and mRNA expression in neighboring CD4 T cells. Moreover, antibody blockade of Tregs inhibitory proteins resulted in increased HIV-1 LTR transcription in co-cultured CD4 T cells. Thus, Tregs inhibit HIV-1 infection of other CD4 T cell subsets via interactions with inhibitory cell surface proteins. Copyright © 2018 Elsevier Inc. All rights reserved.

Generation of human anti-MUC3 IgG antibodies after in vitro immunization of naive peripheral blood B-lymphocytes.

PubMed

Baritaki, S; Zafiropoulos, A; Georgopoulos, E; Souris, S; Krambovitis, E

2001-04-01

It has been demonstrated that IgG antibodies can be generated to self-antigen peptides as well as against viral antigens by an antigen-specific in vitro immunization system of resting human peripheral B-lymphocytes. Using a synthetic peptide from the consensus variable tandem-repeat region of the MUC3 mucin (TSSITTTGTTSHSTPSP) as the B cell epitope, we immunized blood donor B-lymphocytes in vitro and tested for MUC3-specific antibodies by ELISA. After the primary activation step all antibodies were IgM. At the end of the secondary immunization step we obtained 1.8% (21/1138) of the cultures with IgG-switched antibodies. In a competitive inhibition ELISA using the MUC1, MUC2, MUC3, MUC4 and PIP2 peptides, only one culture (F8.1) gave satisfactory specific inhibition. Using this antibody in fluorometric studies, it stained cells from two colon carcinoma cell lines predominantly in the cytoplasm, whereas those from a breast cancer cell line stained predominantly the cell surface. In a preliminary immunohistological evaluation with formalin-fixed sections, the antibody appeared to moderately stain colon sections, but not breast sections or lymph node. This method of in vitro immunization may be a useful tool in generating IgG antibodies specific to self-antigens and could find applications in tumour targeting and immunotherapy.

Vaccination of rhesus macaques with the anthrax vaccine adsorbed vaccine produces a serum antibody response that effectively neutralizes receptor-bound protective antigen in vitro.

PubMed

Clement, Kristin H; Rudge, Thomas L; Mayfield, Heather J; Carlton, Lena A; Hester, Arelis; Niemuth, Nancy A; Sabourin, Carol L; Brys, April M; Quinn, Conrad P

2010-11-01

Anthrax toxin (ATx) is composed of the binary exotoxins lethal toxin (LTx) and edema toxin (ETx). They have separate effector proteins (edema factor and lethal factor) but have the same binding protein, protective antigen (PA). PA is the primary immunogen in the current licensed vaccine anthrax vaccine adsorbed (AVA [BioThrax]). AVA confers protective immunity by stimulating production of ATx-neutralizing antibodies, which could block the intoxication process at several steps (binding of PA to the target cell surface, furin cleavage, toxin complex formation, and binding/translocation of ATx into the cell). To evaluate ATx neutralization by anti-AVA antibodies, we developed two low-temperature LTx neutralization activity (TNA) assays that distinguish antibody blocking before and after binding of PA to target cells (noncomplexed [NC] and receptor-bound [RB] TNA assays). These assays were used to investigate anti-PA antibody responses in AVA-vaccinated rhesus macaques (Macaca mulatta) that survived an aerosol challenge with Bacillus anthracis Ames spores. Results showed that macaque anti-AVA sera neutralized LTx in vitro, even when PA was prebound to cells. Neutralization titers in surviving versus nonsurviving animals and between prechallenge and postchallenge activities were highly correlated. These data demonstrate that AVA stimulates a myriad of antibodies that recognize multiple neutralizing epitopes and confirm that change, loss, or occlusion of epitopes after PA is processed from PA83 to PA63 at the cell surface does not significantly affect in vitro neutralizing efficacy. Furthermore, these data support the idea that the full-length PA83 monomer is an appropriate immunogen for inclusion in next-generation anthrax vaccines.

Selective Individual Primary Cell Capture Using Locally Bio-Functionalized Micropores

PubMed Central

Liu, Jie; Bombera, Radoslaw; Leroy, Loïc; Roupioz, Yoann; Baganizi, Dieudonné R.; Marche, Patrice N.; Haguet, Vincent; Mailley, Pascal; Livache, Thierry

2013-01-01

Background Solid-state micropores have been widely employed for 6 decades to recognize and size flowing unlabeled cells. However, the resistive-pulse technique presents limitations when the cells to be differentiated have overlapping dimension ranges such as B and T lymphocytes. An alternative approach would be to specifically capture cells by solid-state micropores. Here, the inner wall of 15-µm pores made in 10 µm-thick silicon membranes was covered with antibodies specific to cell surface proteins of B or T lymphocytes. The selective trapping of individual unlabeled cells in a bio-functionalized micropore makes them recognizable just using optical microscopy. Methodology/Principal Findings We locally deposited oligodeoxynucleotide (ODN) and ODN-conjugated antibody probes on the inner wall of the micropores by forming thin films of polypyrrole-ODN copolymers using contactless electro-functionalization. The trapping capabilities of the bio-functionalized micropores were validated using optical microscopy and the resistive-pulse technique by selectively capturing polystyrene microbeads coated with complementary ODN. B or T lymphocytes from a mouse splenocyte suspension were specifically immobilized on micropore walls functionalized with complementary ODN-conjugated antibodies targeting cell surface proteins. Conclusions/Significance The results showed that locally bio-functionalized micropores can isolate target cells from a suspension during their translocation throughout the pore, including among cells of similar dimensions in complex mixtures. PMID:23469221

Designing Trojan Horses | Center for Cancer Research

Cancer.gov

Waging battle against cancer cells without inflicting damage on normal tissue has long been a goal for cancer treatment. A new type of drug called immunotoxins may help make this goal a reality. Much like the Greeks used a wooden horse to get soldiers inside the gates of Troy, immunotoxins use clever genetic engineering to get a lethal toxin inside cancer cells. Each immunotoxin consists of two components an antibody and a toxin that are fused together. The custom-designed antibody acts as a homing signal, seeking out a specific target present on the surface of cancer cells. When the antibody binds its target, the whole immunotoxin is brought inside the cell. Unwittingly, the cancer cell has exposed itself to a powerful poison, a mistake that will likely condemn it to death.

Placenta-specific1 (PLAC1) is a potential target for antibody-drug conjugate-based prostate cancer immunotherapy.

PubMed

Nejadmoghaddam, Mohammad-Reza; Zarnani, Amir-Hassan; Ghahremanzadeh, Ramin; Ghods, Roya; Mahmoudian, Jafar; Yousefi, Maryam; Nazari, Mahboobeh; Ghahremani, Mohammad Hossein; Abolhasani, Maryam; Anissian, Ali; Mahmoudi, Morteza; Dinarvand, Rassoul

2017-10-17

Our recent findings strongly support the idea of PLAC1 being as a potential immunotherapeutic target in prostate cancer (PCa). Here, we have generated and evaluated an anti-placenta-specific1 (PLAC1)-based antibody drug conjugate (ADC) for targeted immunotherapy of PCa. Prostate cancer cells express considerable levels of PLAC1. The Anti-PLAC1 clone, 2H12C12, showed high reactivity with recombinant PLAC1 and selectivity recognized PLAC1 in prostate cancer cells but not in LS180 cells, the negative control. PLAC1 binding induced rapid internalization of the antibody within a few minutes which reached to about 50% after 15 min and almost completed within an hour. After SN38 conjugation to antibody, a drug-antibody ratio (DAR) of about 5.5 was achieved without apparent negative effect on antibody affinity to cell surface antigen. The ADC retained intrinsic antibody activity and showed enhanced and selective cytotoxicity with an IC50 of 62 nM which was about 15-fold lower compared to free drug. Anti-PLAC1-ADC induced apoptosis in human primary prostate cancer cells and prostate cell lines. No apparent cytotoxic effect was observed in in vivo animal safety experiments. Our newly developed anti-PLAC1-based ADCs might pave the way for a reliable, efficient, and novel immunotherapeutic modality for patients with PCa.

A novel lentiviral scFv display library for rapid optimization and selection of high affinity antibodies.

PubMed

Qudsia, Sehar; Merugu, Siva B; Mangukiya, Hitesh B; Hema, Negi; Wu, Zhenghua; Li, Dawei

2018-04-30

Antibody display libraries have become a popular technique to screen monoclonal antibodies for therapeutic purposes. An important aspect of display technology is to generate an optimization library by changing antibody affinity to antigen through mutagenesis and screening the high affinity antibody. In this study, we report a novel lentivirus display based optimization library antibody in which Agtuzumab scFv is displayed on cell membrane of HEK-293T cells. To generate an optimization library, hotspot mutagenesis was performed to achieve diverse antibody library. Based on sequence analysis of randomly selected clones, library size was estimated approximately to be 1.6 × 10 6 . Lentivirus display vector was used to display scFv antibody on cell surface and flow cytometery was performed to check the antibody affinity to antigen. Membrane bound scFv antibodies were then converted to secreted antibody through cre/loxP recombination. One of the mutant clones, M8 showed higher affinity to antigen in flow cytometery analysis. Further characterization of cellular and secreted scFv through western blot showed that antibody affinity was increased by three fold after mutagenesis. This study shows successful construction of a novel antibody library and suggests that hotspot mutagenesis could prove a useful and rapid optimization tool to generate similar libraries with various degree of antigen affinity. Copyright © 2018 Elsevier Inc. All rights reserved.

Single Cell Mass Cytometry for Analysis of Immune System Functional States

PubMed Central

Bjornson, Zach B.; Nolan, Garry P.; Fantl, Wendy J.

2013-01-01

Single cell mass cytometry facilitates high-dimensional, quantitative analysis of the effects of bioactive molecules on cell populations at single-cell resolution. Datasets are generated with antibody panels (upwards of 40) in which each antibody is conjugated to a polymer chelated with a stable metal isotope, usually in the Lanthanide series of the periodic table. Isotope labelled antibodies recognize surface markers to delineate cell types and intracellular signaling molecules to provide a measure of the network state—and thereby demarcating multiple cell state functions such as apoptosis, DNA damage and cell cycle. By measuring all these parameters simultaneously, the signaling state of an individual cell can be measured at its network state. This review will cover the basics of mass cytometry as well as outline steps already taken to allow it to stand aside traditional fluorescence based cytometry in the immunologist’s analytical arsenal in their study of immune states during infection. PMID:23999316

Discovery of cell surface vimentin targeting mAb for direct disruption of GBM tumor initiating cells.

PubMed

Noh, Hyangsoon; Yan, Jun; Hong, Sungguan; Kong, Ling-Yuan; Gabrusiewicz, Konrad; Xia, Xueqing; Heimberger, Amy B; Li, Shulin

2016-11-01

Intracellular vimentin overexpression has been associated with epithelial-mesenchymal transition, metastasis, invasion, and proliferation, but cell surface vimentin (CSV) is less understood. Furthermore, it remains unknown whether CSV can serve as a therapeutic target in CSV-expressing tumor cells. We found that CSV was present on glioblastoma multiforme (GBM) cancer stem cells and that CSV expression was associated with spheroid formation in those cells. A newly developed monoclonal antibody against CSV, 86C, specifically and significantly induced apoptosis and inhibited spheroid formation in GBM cells in vitro. The addition of 86C to GBM cells in vitro also led to rapid internalization of vimentin and decreased GBM cell viability. These findings were associated with an increase in caspase-3 activity, indicating activation of apoptosis. Finally, treatment with 86C inhibited GBM progression in vivo. In conclusion, CSV-expressing GBM cells have properties of tumor initiating cells, and targeting CSV with the monoclonal antibody 86C is a promising approach in the treatment of GBM.

B Cell and Antibody Responses in Mice Induced by a Putative Cell Surface Peptidase of Pneumocystis murina Protect against Experimental Infection

PubMed Central

Ruan, Sanbao; Cai, Yang; Ramsay, Alistair J.; Welsh, David A.; Norris, Karen; Shellito, Judd E.

2016-01-01

Rationale Pneumocystis pneumonia is a major cause of morbidity and mortality in HIV-infected subjects, cancer patients undergoing chemotherapy and solid organ transplant recipients. No vaccine is currently available. By chemical labeling coupled with proteomic approach, we have identified a putative surface protein (SPD1, Broad Institute gene accession number PNEG_01848) derived from single suspended P. murina cysts. SPD1 was expressed in an insect cell line and tested for vaccine development. Methods Mice were immunized with SPD1 plus adjuvant MF-59 by subcutaneous injection. Three weeks after the last immunization, CD4+ cells were depleted with anti-CD4 antibody GK1.5. The mice were then challenged with 2 × 105 Pneumocystis organisms. Mice were sacrificed at 4 and 6 weeks after PC challenge. Spleen/lung cells and serum were harvested. B cells and memory B cells were assessed via flow cytometry. Specific Pneumocystis IgG antibody was measured by ELISA before and after challenge. Infection burden was measured as real-time PCR for P. murina rRNA. Results Normal mice infected with Pneumocystis mounted a serum IgG antibody response to SPD1. Serum from rhesus macaques exposed to Pneumocystis showed a similar serum IgG response to purified SPD1. SPD1 immunization increased B cell and memory B cell absolute cell counts in CD4-depleted Balb/c mice post Pneumocystis challenge in spleen and lung. Immunization with SPD1 significantly increased specific Pneumocystis IgG antibody production before and after challenge. Mice immunized with SPD1 showed significantly decreased P. murina copy number compared with mice that did not receive SPD1 at 6 weeks after challenge. Conclusion Immunization with SPD1 provides protective efficacy against P. murina infection. SPD1 protection against Pneumocystis challenge is associated with enhanced memory B cell production and higher anti–Pneumocystis IgG antibody production. SPD1 is a potential vaccine candidate to prevent or treat pulmonary infection with Pneumocystis. PMID:28012778

Rapid screening and identification of dominant B cell epitopes of HBV surface antigen by quantum dot-based fluorescence polarization assay

NASA Astrophysics Data System (ADS)

Meng, Zhongji; Song, Ruihua; Chen, Yue; Zhu, Yang; Tian, Yanhui; Li, Ding; Cui, Daxiang

2013-03-01

A method for quickly screening and identifying dominant B cell epitopes was developed using hepatitis B virus (HBV) surface antigen as a target. Eleven amino acid fragments from HBV surface antigen were synthesized by 9-fluorenylmethoxy carbonyl solid-phase peptide synthesis strategy, and then CdTe quantum dots were used to label the N-terminals of all peptides. After optimizing the factors for fluorescence polarization (FP) immunoassay, the antigenicities of synthetic peptides were determined by analyzing the recognition and combination of peptides and standard antibody samples. The results of FP assays confirmed that 10 of 11 synthetic peptides have distinct antigenicities. In order to screen dominant antigenic peptides, the FP assays were carried out to investigate the antibodies against the 10 synthetic peptides of HBV surface antigen respectively in 159 samples of anti-HBV surface antigen-positive antiserum. The results showed that 3 of the 10 antigenic peptides may be immunodominant because the antibodies against them existed more widely among the samples and their antibody titers were higher than those of other peptides. Using three dominant antigenic peptides, 293 serum samples were detected for HBV infection by FP assays; the results showed that the antibody-positive ratio was 51.9% and the sensitivity and specificity were 84.3% and 98.2%, respectively. In conclusion, a quantum dot-based FP assay is a very simple, rapid, and convenient method for determining immunodominant antigenic peptides and has great potential in applications such as epitope mapping, vaccine designing, or clinical disease diagnosis in the future.

Influenza virus resistance to human neutralizing antibodies.

PubMed

Crowe, James E

2012-01-01

The human antibody repertoire has an exceptionally large capacity to recognize new or changing antigens through combinatorial and junctional diversity established at the time of V(D)J recombination and through somatic hypermutation. Influenza viruses exhibit a relentless capacity to escape the human antibody response by altering the amino acids of their surface proteins in hypervariable domains that exhibit a high level of structural plasticity. Both parties in this high-stakes game of shape shifting drive structural evolution of their functional proteins (the B cell receptor/antibody on one side and the viral hemagglutinin and neuraminidase proteins on the other) using error-prone polymerase systems. It is likely that most of the genetic mutations that occur in these systems are deleterious, resulting in the failure of the B cell or virus with mutations to propagate in the immune repertoire or viral quasispecies. A subset of mutations is tolerated in functional surface proteins that enter the B cell or virus progeny pool. In both cases, selection occurs in the population of mutated and unmutated species. In cases where the functional avidity of the B cell receptor is increased significantly, that clone may be selected for preferential expansion. In contrast, an influenza virus that "escapes" the inhibitory effect of secreted antibodies may represent a high proportion of the progeny virus in that host. The recent paper by O'Donnell et al. [C. D. O'Donnell et al., mBio 3(3):e00120-12, 2012] identifies a mechanism for antibody resistance that does not require escape from binding but rather achieves a greater efficiency in replication.

Charge heterogeneity: Basic antibody charge variants with increased binding to Fc receptors

PubMed Central

Hintersteiner, Beate; Lingg, Nico; Zhang, Peiqing; Woen, Susanto; Hoi, Kong Meng; Stranner, Stefan; Wiederkum, Susanne; Mutschlechner, Oliver; Schuster, Manfred; Loibner, Hans; Jungbauer, Alois

2016-01-01

ABSTRACT We identified active isoforms of the chimeric anti-GD2 antibody, ch14.18, a recombinant antibody produced in Chinese hamster ovary cells, which is already used in clinical trials.1,2,3 We separated the antibody by high resolution ion-exchange chromatography with linear pH gradient elution into acidic, main and basic charge variants on a preparative scale yielding enough material for an in-depth study of the sources and the effects of microheterogeneity. The binding affinity of the charge variants toward the antigen and various cell surface receptors was studied by Biacore. Effector functions were evaluated using cellular assays for antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. Basic charge variants showed increased binding to cell surface receptor FcγRIIIa, which plays a major role in regulating effector functions. Furthermore, increased binding of the basic fractions to the neonatal receptor was observed. As this receptor mediates the prolonged half-life of IgG in human serum, this data may well hint at an increased serum half-life of these basic variants compared to their more acidic counterparts. Different glycoform patterns, C-terminal lysine clipping and N-terminal pyroglutamate formation were identified as the main structural sources for the observed isoform pattern. Potential differences in structural stability between individual charge variant fractions by nano differential scanning calorimetry could not been detected. Our in-vitro data suggests that the connection between microheterogeneity and the biological activity of recombinant antibody therapeutics deserves more attention than commonly accepted. PMID:27559765

Large-scale sequence and structural comparisons of human naive and antigen-experienced antibody repertoires.

PubMed

DeKosky, Brandon J; Lungu, Oana I; Park, Daechan; Johnson, Erik L; Charab, Wissam; Chrysostomou, Constantine; Kuroda, Daisuke; Ellington, Andrew D; Ippolito, Gregory C; Gray, Jeffrey J; Georgiou, George

2016-05-10

Elucidating how antigen exposure and selection shape the human antibody repertoire is fundamental to our understanding of B-cell immunity. We sequenced the paired heavy- and light-chain variable regions (VH and VL, respectively) from large populations of single B cells combined with computational modeling of antibody structures to evaluate sequence and structural features of human antibody repertoires at unprecedented depth. Analysis of a dataset comprising 55,000 antibody clusters from CD19(+)CD20(+)CD27(-) IgM-naive B cells, >120,000 antibody clusters from CD19(+)CD20(+)CD27(+) antigen-experienced B cells, and >2,000 RosettaAntibody-predicted structural models across three healthy donors led to a number of key findings: (i) VH and VL gene sequences pair in a combinatorial fashion without detectable pairing restrictions at the population level; (ii) certain VH:VL gene pairs were significantly enriched or depleted in the antigen-experienced repertoire relative to the naive repertoire; (iii) antigen selection increased antibody paratope net charge and solvent-accessible surface area; and (iv) public heavy-chain third complementarity-determining region (CDR-H3) antibodies in the antigen-experienced repertoire showed signs of convergent paired light-chain genetic signatures, including shared light-chain third complementarity-determining region (CDR-L3) amino acid sequences and/or Vκ,λ-Jκ,λ genes. The data reported here address several longstanding questions regarding antibody repertoire selection and development and provide a benchmark for future repertoire-scale analyses of antibody responses to vaccination and disease.

BST-2 Expression Modulates Small CD4-Mimetic Sensitization of HIV-1-Infected Cells to Antibody-Dependent Cellular Cytotoxicity

PubMed Central

Prévost, Jérémie; von Bredow, Benjamin; Ding, Shilei; Brassard, Nathalie; Medjahed, Halima; Coutu, Mathieu; Melillo, Bruno; Bibollet-Ruche, Frédéric; Hahn, Beatrice H.; Kaufmann, Daniel E.; Smith, Amos B.; Sodroski, Joseph; Sauter, Daniel; Kirchhoff, Frank; Gee, Katrina; Neil, Stuart J.; Evans, David T.

2017-01-01

ABSTRACT Antibodies recognizing conserved CD4-induced (CD4i) epitopes on human immunodeficiency virus type 1 (HIV-1) Env and able to mediate antibody-dependent cellular cytotoxicity (ADCC) have been shown to be present in sera from most HIV-1-infected individuals. These antibodies preferentially recognize Env in its CD4-bound conformation. CD4 downregulation by Nef and Vpu dramatically reduces exposure of CD4i HIV-1 Env epitopes and therefore reduce the susceptibility of HIV-1-infected cells to ADCC mediated by HIV-positive (HIV+) sera. Importantly, this mechanism of immune evasion can be circumvented with small-molecule CD4 mimetics (CD4mc) that are able to transition Env into the CD4-bound conformation and sensitize HIV-1-infected cells to ADCC mediated by HIV+ sera. However, HIV-1 developed additional mechanisms to avoid ADCC, including Vpu-mediated BST-2 antagonism, which decreases the overall amount of Env present at the cell surface. Accordingly, BST-2 upregulation in response to alpha interferon (IFN-α) was shown to increase the susceptibility of HIV-1-infected cells to ADCC despite the activity of Vpu. Here we show that BST-2 upregulation by IFN-β and interleukin-27 (IL-27) also increases the surface expression of Env and thus boosts the ability of CD4mc to sensitize HIV-1-infected cells to ADCC by sera from HIV-1-infected individuals. IMPORTANCE HIV-1 evolved sophisticated strategies to conceal Env epitopes from ADCC-mediating antibodies present in HIV+ sera. Vpu-mediated BST-2 downregulation was shown to decrease ADCC responses by limiting the amount of Env present at the cell surface. This effect of Vpu was shown to be attenuated by IFN-α treatment. Here we show that in addition to IFN-α, IFN-β and IL-27 also affect Vpu-mediated BST-2 downregulation and greatly enhance ADCC responses against HIV-1-infected cells in the presence of CD4mc. These findings may inform strategies aimed at HIV prevention and eradication. PMID:28331088

Enhanced sensitivity in detection of antiviral antibody responses using biotinylation of foot-and-mouth disease virus (FMDV) capsids.

PubMed

Kenney, Mary; Waters, Ryan A; Rieder, Elizabeth; Pega, Juan; Perez-Filguera, Mariano; Golde, William T

2017-11-01

Analysis of the immune response to infection of livestock by foot-and-mouth disease virus (FMDV) is most often reported as the serum antibody response to the virus. While measurement of neutralizing antibody has been sensitive and specific, measurements of the quality of the antibody response are less robust. Determining the immunoglobulin (Ig) isotype of the serum antibody response provides a deeper understanding of the biology of the response and more sensitive methods for these assays will facilitate analyses of B cell mediated immunity. We tested the hypothesis that using the virus as the molecular probe could be achieved by adding tags to the surface of the FMDV capsid, and that would enhance sensitivity in assays for anti-FMDV antibody responses. The use of a FLAG-tagged virus in these assays failed to yield improvement whereas chemically biotinylating the virus capsid resulted in significant enhancement of the signal. Here we describe methods using biotinylated virus for measuring anti-viral antibody in serum and antibody secreting cells (ASCs) in blood that are sensitive and specific. Finally, we describe using the biotinylated virus in flow cytometry where such assays should greatly enhance the analysis of anti-virus antibody producing B cells, allowing the investigator to focus on only the FMDV specific B cells when analyzing the development of the B cell response to either infection or vaccination. Published by Elsevier B.V.

Presence of Epstein-Barr virus-infected B lymphocytes with thyrotropin receptor antibodies on their surface in Graves' disease patients and in healthy individuals.

PubMed

Nagata, Keiko; Higaki, Katsumi; Nakayama, Yuji; Miyauchi, Hiromi; Kiritani, Yui; Kanai, Kyosuke; Matsushita, Michiko; Iwasaki, Takeshi; Sugihara, Hirotsugu; Kuwamoto, Satoshi; Kato, Masako; Murakami, Ichiro; Nanba, Eiji; Kimura, Hiroshi; Hayashi, Kazuhiko

2014-05-01

Graves' disease is an autoimmune hyperthyroidism caused by thyrotropin receptor antibodies (TRAbs). Because Epstein-Barr virus (EBV) persists in B cells and is occasionally reactivated, we hypothesized that EBV contributes to TRAbs production in Graves' disease patients by stimulating the TRAbs-producing B cells. In order for EBV to stimulate antibody-producing cells, EBV must be present in those cells but that have not yet been observed. We examined whether EBV-infected (EBV(+)) B cells with TRAbs on their surface (TRAbs(+)) as membrane immunoglobulin were present in peripheral blood of Graves' disease patients. We analyzed cultured or non-cultured peripheral blood mononuclear cells (PBMCs) from 13 patients and 11 healthy controls by flow-cytometry and confocal laser microscopy, and confirmed all cultured PBMCs from 8 patients really had TRAbs(+) EBV(+) double positive cells. We unexpectedly detected TRAbs(+) cells in all healthy controls, and TRAbs(+) EBV(+) double positive cells in all cultured PBMC from eight healthy controls. The frequency of TRAbs(+) cells in cultured PBMCs was significantly higher in patients than in controls (p = 0.021). In this study, we indicated the presence of EBV-infected B lymphocytes with TRAbs on their surface, a possible player of the production of excessive TRAbs, the causative autoantibody for Graves' disease. This is a basic evidence for our hypothesis that EBV contributes to TRAbs production in Graves' disease patients. Our results further suggest that healthy controls have the potential for TRAbs production. This gives us an important insight into the pathogenesis of Graves' disease.

Presence of Epstein–Barr virus-infected B lymphocytes with thyrotropin receptor antibodies on their surface in Graves’ disease patients and in healthy individuals

PubMed Central

Nagata, Keiko; Higaki, Katsumi; Nakayama, Yuji; Miyauchi, Hiromi; Kiritani, Yui; Kanai, Kyosuke; Matsushita, Michiko; Iwasaki, Takeshi; Sugihara, Hirotsugu; Kuwamoto, Satoshi; Kato, Masako; Murakami, Ichiro; Nanba, Eiji; Kimura, Hiroshi; Hayashi, Kazuhiko

2014-01-01

Abstract Graves’ disease is an autoimmune hyperthyroidism caused by thyrotropin receptor antibodies (TRAbs). Because Epstein–Barr virus (EBV) persists in B cells and is occasionally reactivated, we hypothesized that EBV contributes to TRAbs production in Graves’ disease patients by stimulating the TRAbs-producing B cells. In order for EBV to stimulate antibody-producing cells, EBV must be present in those cells but that have not yet been observed. We examined whether EBV-infected (EBV(+)) B cells with TRAbs on their surface (TRAbs(+)) as membrane immunoglobulin were present in peripheral blood of Graves’ disease patients. We analyzed cultured or non-cultured peripheral blood mononuclear cells (PBMCs) from 13 patients and 11 healthy controls by flow-cytometry and confocal laser microscopy, and confirmed all cultured PBMCs from 8 patients really had TRAbs(+) EBV(+) double positive cells. We unexpectedly detected TRAbs(+) cells in all healthy controls, and TRAbs(+) EBV(+) double positive cells in all cultured PBMC from eight healthy controls. The frequency of TRAbs(+) cells in cultured PBMCs was significantly higher in patients than in controls (p = 0.021). In this study, we indicated the presence of EBV-infected B lymphocytes with TRAbs on their surface, a possible player of the production of excessive TRAbs, the causative autoantibody for Graves’ disease. This is a basic evidence for our hypothesis that EBV contributes to TRAbs production in Graves’ disease patients. Our results further suggest that healthy controls have the potential for TRAbs production. This gives us an important insight into the pathogenesis of Graves’ disease. PMID:24467196

Engineering antigens for in situ erythrocyte binding induces T-cell deletion.

PubMed

Kontos, Stephan; Kourtis, Iraklis C; Dane, Karen Y; Hubbell, Jeffrey A

2013-01-02

Antigens derived from apoptotic cell debris can drive clonal T-cell deletion or anergy, and antigens chemically coupled ex vivo to apoptotic cell surfaces have been shown correspondingly to induce tolerance on infusion. Reasoning that a large number of erythrocytes become apoptotic (eryptotic) and are cleared each day, we engineered two different antigen constructs to target the antigen to erythrocyte cell surfaces after i.v. injection, one using a conjugate with an erythrocyte-binding peptide and another using a fusion with an antibody fragment, both targeting the erythrocyte-specific cell surface marker glycophorin A. Here, we show that erythrocyte-binding antigen is collected much more efficiently than free antigen by splenic and hepatic immune cell populations and hepatocytes, and that it induces antigen-specific deletional responses in CD4(+) and CD8(+) T cells. We further validated T-cell deletion driven by erythrocyte-binding antigens using a transgenic islet β cell-reactive CD4(+) T-cell adoptive transfer model of autoimmune type 1 diabetes: Treatment with the peptide antigen fused to an erythrocyte-binding antibody fragment completely prevented diabetes onset induced by the activated, autoreactive CD4(+) T cells. Thus, we report a translatable modular biomolecular approach with which to engineer antigens for targeted binding to erythrocyte cell surfaces to induce antigen-specific CD4(+) and CD8(+) T-cell deletion toward exogenous antigens and autoantigens.

Cloning and expression of canine CD25 for validation of an anti-human CD25 antibody to compare T regulatory lymphocytes in healthy dogs and dogs with osteosarcoma.

PubMed

Rissetto, K C; Rindt, H; Selting, K A; Villamil, J A; Henry, C J; Reinero, C R

2010-05-15

T regulatory cells (Tregs) are a unique subset of T helper cells that serve to modify/inhibit effector cells of the immune system and thus are essential to prevent autoimmunity. Overzealous Treg activity may contribute to impaired immune responses to cancer. Tregs can be phenotypically identified by proteins expressed on the cell surface (CD4 and CD25) and inside the cell (forkhead box3 (FoxP3)), although in dogs, no anti-canine CD25 antibody exists. We hypothesized that a mouse anti-human CD25 antibody definitively recognizes the canine protein and can be used to identify Tregs in dogs. We describe cloning and transfection of the canine CD25 gene into human HeLa cells with subsequent expression of the canine protein on the cell surface detected using an anti-human CD25 antibody in a flow cytometric assay. Validation of this antibody was used to identify CD4+CD25+FoxP3+ Tregs in 39 healthy dogs and 16 dogs with osteosarcoma (OSA). Results were expressed in five different ways and showed significantly fewer %CD4+CD25+ T lymphocytes expressing FoxP3 in blood of older dogs (>/=7 years) compared with the other two age groups (<2 and 2-6 years) (p<0.001) and fewer %CD4+CD25+FoxP3+ Tregs in the tumor draining lymph nodes of OSA patients compared to the unrelated lymph node (p=0.049). However, there was no significant difference in % Tregs in the peripheral blood or lymph nodes between the control dogs and those with OSA. While the CD25 antibody can be successfully used in a flow cytometric assay to identify Tregs, this study does not support clinical utility of phenotypic recognition of Tregs in dogs with OSA. Copyright 2010 Elsevier B.V. All rights reserved.

A preclinical study comparing approaches for augmenting the immunogenicity of a heptavalent KLH-conjugate vaccine against epithelial cancers.

PubMed

Ragupathi, Govind; Koide, Fusataka; Sathyan, Natarajan; Kagan, Ella; Spassova, Maria; Bornmann, William; Gregor, Polly; Reis, Celso A; Clausen, Henrik; Danishefsky, Samuel J; Livingston, Philip O

2003-10-01

Previously using a series of monovalent vaccines, we demonstrated that the optimal method for inducing an antibody response against cancer cell-surface antigens is covalent conjugation of the antigens to keyhole limpet hemocyanin (KLH) and the use of a saponin adjuvant. We have prepared a heptavalent-KLH conjugate vaccine containing the seven epithelial cancer antigens GM2, Globo H, Lewis(y), TF(c), Tn(c), STn(c), and glycosylated MUC1. In preparation for testing this vaccine in the clinic, we tested the impact on antibody induction of administering the individual conjugates plus adjuvant compared with a mixture of the seven conjugates plus adjuvant, and of several variables thought to augment immunogenicity. These include approaches for decreasing suppressor cell activity or increasing helper T-lymphocyte activity (low dose cyclophosphamide or anti-CTLA-4 MAb), different saponin adjuvants at various doses (QS-21 and GPI-0100), and different methods of formulation (lyophilization and use of polysorbate 80). We find that: (1). Immunization with the heptavalent-KLH conjugate plus GPI-0100 vaccine induces antibodies against the seven antigens of comparable titer to those induced by the individual-KLH conjugate vaccines, high titers of antibodies against Tn (median ELISA titer IgM/IgG 320/10240), STn (640/5120), TF (320/10240), MUC1 (80/20480), and globo H (640/40); while lower titers of antibodies against Lewis(y)()(160/0) and only occasional antibodies against GM2 are induced. (2). These antibodies reacted with the purified synthetic antigens by ELISA, and with naturally expressed antigens on the cancer cell surface by FACS. (3). None of the approaches for further altering the suppressor cell/helper T-cell balance nor changes to the standard formulation by lyophilization or use of polysorbate 80 had any impact on antibody titers. (4). An optimal dose of saponin adjuvant, QS-21 (50 microg) or GPI-0100 (1000 microg), is required for optimal antibody titers. This heptavalent vaccine is sufficiently optimized for testing in the clinic.

Serum antibodies to outer membrane proteins (OMPs) of Moraxella (Branhamella) catarrhalis in patients with bronchiectasis: identification of OMP B1 as an important antigen.

PubMed Central

Sethi, S; Hill, S L; Murphy, T F

1995-01-01

Moraxella (Branhamella) catarrhalis is a common cause of lower respiratory tract infections in adults and of otitis media in children. Little is known about the human immune response to this bacterium. In this study, immunoblot assays were performed to detect serum immunoglobulin G antibodies directed at purified outer membrane of M. catarrhalis. Twelve serum samples, two each from six patients with bronchiectasis who were persistently colonized with this organism, were tested with their homologous M. catarrhalis sputum isolates. In all the sera, the most prominent and consistent antibody response was to a minor 84-kDa outer membrane protein, OMP B1. Immunoblot adsorption assays show that these antibodies recognize surface exposed epitopes on OMP B1. Further analysis of human serum antibodies eluted from the surface of intact bacterial cells shows that these surface-exposed epitopes on OMP B1 are heterogeneous among strains of M. catarrhalis. OMP B1 is therefore an important OMP antigen on the surface of M. catarrhalis for the human immune response to infection by this bacterium. PMID:7890418

Expression of full-length HER2 protein in Sf9 insect cells and its presentation on the surface of budded virus-like particles.

PubMed

Nika, Lisa; Wallner, Jakob; Palmberger, Dieter; Koczka, Krisztina; Vorauer-Uhl, Karola; Grabherr, Reingard

2017-08-01

Biomarkers of cancer are often glycosylated membrane receptor proteins present on the cellular surface. In order to develop new antibodies for cancer diagnostics or treatment, it is a main pre-requisite that these target proteins are available in a native conformation. However, membrane receptor proteins are notoriously difficult to produce due to their hydrophobic nature and complex architecture. Here, we used the baculovirus-insect cell expression system to produce budded virus-like particles (VLPs) as the scaffold for the presentation of complex membrane proteins. Since the human epidermal growth factor receptor 2 (HER2) is known to be overexpressed in a number of cancers it was chosen as model for a tumor antigen. VLPs displaying full-length HER2 on the surface were produced in Spodoptera frugiperda 9 (Sf9) insect cells and purified by sucrose gradient ultracentrifugation. The number of secreted particles was quantified by nanoparticle tracking analysis. To confirm the presence of HER2 protein on the surface, VLPs were labeled with gold-conjugated antibodies and analyzed by transmission electron microscopy. Functionality of displayed HER2 was investigated by ELISA and a newly established biolayer interferometry based technique. Detection was accomplished using the specific monoclonal antibody Herceptin and filamentous phages displaying a single-chain variable fragment of an anti-HER2 antibody. Significant stronger binding of Herceptin and anti-HER2 phages to HER2-displaying VLPs as compared to control VLPs was demonstrated. Thus, we suggest that Sf9 insect cells are highly feasible for the fast and easy production of various budded VLPs that serve as a platform for full-length membrane receptor presentation. Copyright © 2017. Published by Elsevier Inc.

SIRPA is a specific cell-surface marker for isolating cardiomyocytes derived from human pluripotent stem cells.

PubMed

Dubois, Nicole C; Craft, April M; Sharma, Parveen; Elliott, David A; Stanley, Edouard G; Elefanty, Andrew G; Gramolini, Anthony; Keller, Gordon

2011-10-23

To identify cell-surface markers specific to human cardiomyocytes, we screened cardiovascular cell populations derived from human embryonic stem cells (hESCs) against a panel of 370 known CD antibodies. This screen identified the signal-regulatory protein alpha (SIRPA) as a marker expressed specifically on cardiomyocytes derived from hESCs and human induced pluripotent stem cells (hiPSCs), and PECAM, THY1, PDGFRB and ITGA1 as markers of the nonmyocyte population. Cell sorting with an antibody against SIRPA allowed for the enrichment of cardiac precursors and cardiomyocytes from hESC/hiPSC differentiation cultures, yielding populations of up to 98% cardiac troponin T-positive cells. When plated in culture, SIRPA-positive cells were contracting and could be maintained over extended periods of time. These findings provide a simple method for isolating populations of cardiomyocytes from human pluripotent stem cell cultures, and thereby establish a readily adaptable technology for generating large numbers of enriched cardiomyocytes for therapeutic applications.

Monoclonal antibodies against GARP/TGF-β1 complexes inhibit the immunosuppressive activity of human regulatory T cells in vivo.

PubMed

Cuende, Julia; Liénart, Stéphanie; Dedobbeleer, Olivier; van der Woning, Bas; De Boeck, Gitte; Stockis, Julie; Huygens, Caroline; Colau, Didier; Somja, Joan; Delvenne, Philippe; Hannon, Muriel; Baron, Frédéric; Dumoutier, Laure; Renauld, Jean-Christophe; De Haard, Hans; Saunders, Michael; Coulie, Pierre G; Lucas, Sophie

2015-04-22

Regulatory T cells (Tregs) are essential to prevent autoimmunity, but excessive Treg function contributes to cancer progression by inhibiting antitumor immune responses. Tregs exert contact-dependent inhibition of immune cells through the production of active transforming growth factor-β1 (TGF-β1). On the Treg cell surface, TGF-β1 is in an inactive form bound to membrane protein GARP and then activated by an unknown mechanism. We demonstrate that GARP is involved in this activation mechanism. Two anti-GARP monoclonal antibodies were generated that block the production of active TGF-β1 by human Tregs. These antibodies recognize a conformational epitope that requires amino acids GARP137-139 within GARP/TGF-β1 complexes. A variety of antibodies recognizing other GARP epitopes did not block active TGF-β1 production by Tregs. In a model of xenogeneic graft-versus-host disease in NSG mice, the blocking antibodies inhibited the immunosuppressive activity of human Tregs. These antibodies may serve as therapeutic tools to boost immune responses to infection or cancer via a mechanism of action distinct from that of currently available immunomodulatory antibodies. Used alone or in combination with tumor vaccines or antibodies targeting the CTLA4 or PD1/PD-L1 pathways, blocking anti-GARP antibodies may improve the efficiency of cancer immunotherapy. Copyright © 2015, American Association for the Advancement of Science.

Identification and quantification of the rat hepatocyte asialoglycoprotein receptor.

PubMed Central

Schwartz, A L; Marshak-Rothstein, A; Rup, D; Lodish, H F

1981-01-01

The asialoglycoprotein receptor from rat liver was purified by solubilization and affinity chromatography on asialoorosomucoid-Sepharose. The preparation yielded four distinct polypeptides of Mr 40,000-120,000. We prepared a monoclonal antibody that both immunoprecipitates solubilized receptor activity and blocks the binding of galactose-terminal glycoproteins to immobilized receptor. The monoclonal antibody and a rabbit antireceptor antiserum immunoprecipitated all four polypeptide species. Peptide analysis by two-dimensional chromatography of the individual 125I-labeled species showed nearly identical patterns, which also suggested that the four polypeptides have a similar primary structure. To identify and quantitate the asialoglycoprotein receptor on the hepatocyte cell surface, intact cells were iodinated with lactoperoxidase, and the solubilized membranes were treated with antireceptor antibody. The Mr 55,000 and Mr 65,000 species were the major species found. Our results suggest that the Mr of the surface receptor is at least 55,000 and that it comprises between 1-2% of the iodinated hepatocyte surface protein. Images PMID:6267585

Novel mechanism of antibodies to hepatitis B virus in blocking viral particle release from cells.

PubMed

Neumann, Avidan U; Phillips, Sandra; Levine, Idit; Ijaz, Samreen; Dahari, Harel; Eren, Rachel; Dagan, Shlomo; Naoumov, Nikolai V

2010-09-01

Antibodies are thought to exert antiviral activities by blocking viral entry into cells and/or accelerating viral clearance from circulation. In particular, antibodies to hepatitis B virus (HBV) surface antigen (HBsAg) confer protection, by binding circulating virus. Here, we used mathematical modeling to gain information about viral dynamics during and after single or multiple infusions of a combination of two human monoclonal anti-HBs (HepeX-B) antibodies in patients with chronic hepatitis B. The antibody HBV-17 recognizes a conformational epitope, whereas antibody HBV-19 recognizes a linear epitope on the HBsAg. The kinetic profiles of the decline of serum HBV DNA and HBsAg revealed partial blocking of virion release from infected cells as a new antiviral mechanism, in addition to acceleration of HBV clearance from the circulation. We then replicated this approach in vitro, using cells secreting HBsAg, and compared the prediction of the mathematical modeling obtained from the in vivo kinetics. In vitro, HepeX-B treatment of HBsAg-producing cells showed cellular uptake of antibodies, resulting in intracellular accumulation of viral particles. Blocking of HBsAg secretion also continued after HepeX-B was removed from the cell culture supernatants. These results identify a novel antiviral mechanism of antibodies to HBsAg (anti-HBs) involving prolonged blocking of the HBV and HBsAg subviral particles release from infected cells. This may have implications in designing new therapies for patients with chronic HBV infection and may also be relevant in other viral infections.

A novel anti-GPC3 monoclonal antibody (YP7) | Center for Cancer Research

Cancer.gov

Glypican-3 (GPC3) is an emerging therapeutic target in hepatoma. A novel anti-GPC3 monoclonal antibody (YP7) has been generated through a combination of peptide immunization and high-throughput flow cytometry screening. YP7 binds cell-surface-associated GPC3 with high affinity and exhibits significant hepatoma xenograft growth inhibition in nude mice. The new antibody may have

Concise Review: Cell Surface N-Linked Glycoproteins as Potential Stem Cell Markers and Drug Targets.

PubMed

Boheler, Kenneth R; Gundry, Rebekah L

2017-01-01

Stem cells and their derivatives hold great promise to advance regenerative medicine. Critical to the progression of this field is the identification and utilization of antibody-accessible cell-surface proteins for immunophenotyping and cell sorting-techniques essential for assessment and isolation of defined cell populations with known functional and therapeutic properties. Beyond their utility for cell identification and selection, cell-surface proteins are also major targets for pharmacological intervention. Although comprehensive cell-surface protein maps are highly valuable, they have been difficult to define until recently. In this review, we discuss the application of a contemporary targeted chemoproteomic-based technique for defining the cell-surface proteomes of stem and progenitor cells. In applying this approach to pluripotent stem cells (PSCs), these studies have improved the biological understanding of these cells, led to the enhanced use and development of antibodies suitable for immunophenotyping and sorting, and contributed to the repurposing of existing drugs without the need for high-throughput screening. The utility of this latter approach was first demonstrated with human PSCs (hPSCs) through the identification of small molecules that are selectively toxic to hPSCs and have the potential for eliminating confounding and tumorigenic cells in hPSC-derived progeny destined for research and transplantation. Overall, the cutting-edge technologies reviewed here will accelerate the development of novel cell-surface protein targets for immunophenotyping, new reagents to improve the isolation of therapeutically qualified cells, and pharmacological studies to advance the treatment of intractable diseases amenable to cell-replacement therapies. Stem Cells Translational Medicine 2017;6:131-138. © 2016 The Authors Stem Cells Translational Medicine published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Neuronal surface antigen antibodies in limbic encephalitis: clinical-immunologic associations.

PubMed

Graus, F; Saiz, A; Lai, M; Bruna, J; López, F; Sabater, L; Blanco, Y; Rey, M J; Ribalta, T; Dalmau, J

2008-09-16

To report the frequency and type of antibodies against neuronal surface antigens (NSA-ab) in limbic encephalitis (LE). Analysis of clinical features, neuropathologic findings, and detection of NSA-ab using immunochemistry on rat tissue and neuronal cultures in a series of 45 patients with paraneoplastic (23) or idiopathic (22) LE. NSA-ab were identified in 29 patients (64%; 12 paraneoplastic, 17 idiopathic). Thirteen patients had voltage-gated potassium channels (VGKC)-ab, 11 novel NSA (nNSA)-ab, and 5 NMDA receptor (NMDAR)-ab. nNSA-ab did not identify a common antigen and were more frequent in paraneoplastic than idiopathic LE (39% vs 9%; p = 0.03). When compared with VGKC-ab or NMDAR-ab, the nNSA associated more frequently with intraneuronal antibodies (11% vs 73%; p = 0.001). Of 12 patients (9 nNSA-ab, 2 VGKC-ab, 1 NMDAR-ab) with paraneoplastic LE and NSA-ab, concomitant intraneuronal antibodies occurred in 9 (75%). None of these 12 patients improved with immunotherapy. The autopsy of three of them showed neuronal loss, microgliosis, and cytotoxic T cell infiltrates in the hippocampus and amygdala. These findings were compatible with a T-cell mediated neuronal damage. In contrast, 13 of 17 (76%) patients with idiopathic LE and NSA-ab (8 VGKC-ab, 4 NMDAR-ab, 1 nNSA-ab) and 1 of 5 (20%) without antibodies had clinical improvement (p = 0.04). In paraneoplastic limbic encephalitis (LE), novel antibodies against neuronal surface antigens (nNSA-ab) occur frequently, coexist with antibodies against intracellular antigens, and these cases are refractory to immunotherapy. In idiopathic LE, the likelihood of improvement is significantly higher in patients with NSA-ab than in those without antibodies.

Surface Plasmon Resonance kinetic analysis of the interaction between G-quadruplex nucleic acids and an anti-G-quadruplex monoclonal antibody.

PubMed

Lago, Sara; Nadai, Matteo; Rossetto, Monica; Richter, Sara N

2018-06-01

G-quadruplexes (G4s) are nucleic acids secondary structures formed in guanine-rich sequences. Anti-G4 antibodies represent a tool for the direct investigation of G4s in cells. Surface Plasmon Resonance (SPR) is a highly sensitive technology, suitable for assessing the affinity between biomolecules. We here aimed at improving the orientation of an anti-G4 antibody on the SPR sensor chip to optimize detection of binding antigens. SPR was employed to characterize the anti-G4 antibody interaction with G4 and non-G4 oligonucleotides. Dextran-functionalized sensor chips were used both in covalent coupling and capturing procedures. The use of two leading molecule for orienting the antibody of interest allowed to improve its activity from completely non-functional to 65% active. The specificity of the anti-G4 antobody for G4 structures could thus be assessed with high sensitivity and reliability. Optimization of the immobilization protocol for SPR biosensing, allowed us to determine the anti-G4 antibody affinity and specificity for G4 antigens with higher sensitivity with respect to other in vitro assays such as ELISA. Anti-G4 antibody specificity is a fundamental assumption for the future utilization of this kind of antibodies for monitoring G4s directly in cells. The heterogeneous orientation of amine-coupling immobilized ligands is a general problem that often leads to partial or complete inactivation of the molecules. Here we describe a new strategy for improving ligand orientation: driving it from two sides. This principle can be virtually applied to every molecule that loses its activity or is poorly immobilized after standard coupling to the SPR chip surface. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

DNA-based probes for flow cytometry analysis of endocytosis and recycling.

PubMed

Dumont, Claire; Czuba, Ewa; Chen, Moore; Villadangos, Jose A; Johnston, Angus P R; Mintern, Justine D

2017-04-01

The internalization of proteins plays a key role in cell development, cell signaling and immunity. We have previously developed a specific hybridization internalization probe (SHIP) to quantitate the internalization of proteins and particles into cells. Herein, we extend the utility of SHIP to examine both the endocytosis and recycling of surface receptors using flow cytometry. SHIP was used to monitor endocytosis of membrane-bound transferrin receptor (TFR) and its soluble ligand transferrin (TF). SHIP enabled measurements of the proportion of surface molecules internalized, the internalization kinetics and the proportion and rate of internalized molecules that recycle to the cell surface with time. Using this method, we have demonstrated the internalization and recycling of holo-TF and an antibody against the TFR behave differently. This assay therefore highlights the implications of receptor internalization and recycling, where the internalization of the receptor-antibody complex behaves differently to the receptor-ligand complex. In addition, we observe distinct internalization patterns for these molecules expressed by different subpopulations of primary cells. SHIP provides a convenient and high throughput technique for analysis of trafficking parameters for both cell surface receptors and their ligands. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The analysis with monoclonal antibodies of the heterogeneity of Ia glycoproteins on chronic lymphocytic leukemia cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Addis, J.B.; Tisch, R.; Falk, J.A.

The accessible Ia molecules on the surface of chronic lymphocytic leukemia (CLL) cells were quantitated in the cellular radioimmunoassay with saturating concentrations of monoclonal antibodies. Monoclonal antibody 21w4, like DA/2 antibody, recognizes monomorphic determinants of human Ia antigens.The amount of 21w4 or DA/2 bound to CLL cells derived from eight patients (varying from 2.6 to 13.9 x 10/sup 5/ molecules/cell) appears to be the maximum observed with the antibodies studied. Two other antibodies, 18d5 and 21r5, although also directed at nonpolymorphic Ia determinants, bind differentially to CLL cells, with the ratios of 21r5/21w4 and 18d5/21w4 varying from 0.08 to 0.90.more » Sequential immunoprecipitation studies have established that the four epitopes 18d5, 21r5, 21w4, and DA/2 were present on the same molecules. All Ia molecules express 21w4 and DA/2 epitopes, whereas only certain subsets of Ia molecules carry accessible 21r5 or 18d5 epitopes. Competitive binding studies showed that the epitopes recognized by the four monoclonal antibodies were different. Monoclonal antibodies 21r5 and 21w4 did not inhibit each other's binding. Furthermore, binding of 21w4 to CLL cells potentiated the binding of /sup 125/I-21r5 IgG to the same cells, suggesting that binding of 21w4 antibody induces a conformational change in the molecule that renders 21r5 epitopes more accessible.« less

A novel method for measuring cellular antibody uptake using imaging flow cytometry reveals distinct uptake rates for two different monoclonal antibodies targeting L1.

PubMed

Hazin, John; Moldenhauer, Gerhard; Altevogt, Peter; Brady, Nathan R

2015-08-01

Monoclonal antibodies (mAbs) have emerged as a promising tool for cancer therapy. Differing approaches utilize mAbs to either deliver a drug to the tumor cells or to modulate the host's immune system to mediate tumor kill. The rate by which a therapeutic antibody is being internalized by tumor cells is a decisive feature for choosing the appropriate treatment strategy. We herein present a novel method to effectively quantitate antibody uptake of tumor cells by using image-based flow cytometry, which combines image analysis with high throughput of sample numbers and sample size. The use of this method is established by determining uptake rate of an anti-EpCAM antibody (HEA125), from single cell measurements of plasma membrane versus internalized antibody, in conjunction with inhibitors of endocytosis. The method is then applied to two mAbs (L1-9.3, L1-OV52.24) targeting the neural cell adhesion molecule L1 (L1CAM) at two different epitopes. Based on median cell population responses, we find that mAb L1-OV52.24 is rapidly internalized by the ovarian carcinoma cell line SKOV3ip while L1 mAb 9.3 is mainly retained at the cell surface. These findings suggest the L1 mAb OV52.24 as a candidate to be further developed for drug-delivery to cancer cells, while L1-9.3 may be optimized to tag the tumor cells and stimulate immunogenic cancer cell killing. Furthermore, when analyzing cell-to-cell variability, we observed L1 mAb OV52.24 rapidly transition into a subpopulation with high-internalization capacity. In summary, this novel high-content method for measuring antibody internalization rate provides a high level of accuracy and sensitivity for cell population measurements and reveals further biologically relevant information when taking into account cellular heterogeneity. Copyright © 2015 Elsevier B.V. All rights reserved.

Induction of Caveolae in the Apical Plasma Membrane of Madin-Darby Canine Kidney Cells

PubMed Central

Verkade, Paul; Harder, Thomas; Lafont, Frank; Simons, Kai

2000-01-01

In this paper, we have analyzed the behavior of antibody cross-linked raft-associated proteins on the surface of MDCK cells. We observed that cross-linking of membrane proteins gave different results depending on whether cross-linking occurred on the apical or basolateral plasma membrane. Whereas antibody cross-linking induced the formation of large clusters on the basolateral membrane, resembling those observed on the surface of fibroblasts (Harder, T., P. Scheiffele, P. Verkade, and K. Simons. 1998. J. Cell Biol. 929–942), only small (∼100 nm) clusters formed on the apical plasma membrane. Cross-linked apical raft proteins e.g., GPI-anchored placental alkaline phosphatase (PLAP), influenza hemagglutinin, and gp114 coclustered and were internalized slowly (∼10% after 60 min). Endocytosis occurred through surface invaginations that corresponded in size to caveolae and were labeled with caveolin-1 antibodies. Upon cholesterol depletion the internalization of PLAP was completely inhibited. In contrast, when a non-raft protein, the mutant LDL receptor LDLR-CT22, was cross-linked, it was excluded from the clusters of raft proteins and was rapidly internalized via clathrin-coated pits. Since caveolae are normally present on the basolateral membrane but lacking from the apical side, our data demonstrate that antibody cross-linking induced the formation of caveolae, which slowly internalized cross-linked clusters of raft-associated proteins. PMID:10684254

A Rough Energy Landscape to Describe Surface-Linked Antibody and Antigen Bond Formation

NASA Astrophysics Data System (ADS)

Limozin, Laurent; Bongrand, Pierre; Robert, Philippe

2016-10-01

Antibodies and B cell receptors often bind their antigen at cell-cell interface while both molecular species are surface-bound, which impacts bond kinetics and function. Despite the description of complex energy landscapes for dissociation kinetics which may also result in significantly different association kinetics, surface-bound molecule (2D) association kinetics usually remain described by an on-rate due to crossing of a single free energy barrier, and few experimental works have measured association kinetics under conditions implying force and two-dimensional relative ligand-receptor motion. We use a new laminar flow chamber to measure 2D bond formation with systematic variation of the distribution of encounter durations between antigen and antibody, in a range from 0.1 to 10 ms. Under physiologically relevant forces, 2D association is 100-fold slower than 3D association as studied by surface plasmon resonance assays. Supported by brownian dynamics simulations, our results show that a minimal encounter duration is required for 2D association; an energy landscape featuring a rough initial part might be a reasonable way of accounting for this. By systematically varying the temperature of our experiments, we evaluate roughness at 2kBT, in the range of previously proposed rough parts of landscapes models during dissociation.

A Rough Energy Landscape to Describe Surface-Linked Antibody and Antigen Bond Formation

PubMed Central

Limozin, Laurent; Bongrand, Pierre; Robert, Philippe

2016-01-01

Antibodies and B cell receptors often bind their antigen at cell-cell interface while both molecular species are surface-bound, which impacts bond kinetics and function. Despite the description of complex energy landscapes for dissociation kinetics which may also result in significantly different association kinetics, surface-bound molecule (2D) association kinetics usually remain described by an on-rate due to crossing of a single free energy barrier, and few experimental works have measured association kinetics under conditions implying force and two-dimensional relative ligand-receptor motion. We use a new laminar flow chamber to measure 2D bond formation with systematic variation of the distribution of encounter durations between antigen and antibody, in a range from 0.1 to 10 ms. Under physiologically relevant forces, 2D association is 100-fold slower than 3D association as studied by surface plasmon resonance assays. Supported by brownian dynamics simulations, our results show that a minimal encounter duration is required for 2D association; an energy landscape featuring a rough initial part might be a reasonable way of accounting for this. By systematically varying the temperature of our experiments, we evaluate roughness at 2kBT, in the range of previously proposed rough parts of landscapes models during dissociation. PMID:27731375

A Rough Energy Landscape to Describe Surface-Linked Antibody and Antigen Bond Formation.

PubMed

Limozin, Laurent; Bongrand, Pierre; Robert, Philippe

2016-10-12

Antibodies and B cell receptors often bind their antigen at cell-cell interface while both molecular species are surface-bound, which impacts bond kinetics and function. Despite the description of complex energy landscapes for dissociation kinetics which may also result in significantly different association kinetics, surface-bound molecule (2D) association kinetics usually remain described by an on-rate due to crossing of a single free energy barrier, and few experimental works have measured association kinetics under conditions implying force and two-dimensional relative ligand-receptor motion. We use a new laminar flow chamber to measure 2D bond formation with systematic variation of the distribution of encounter durations between antigen and antibody, in a range from 0.1 to 10 ms. Under physiologically relevant forces, 2D association is 100-fold slower than 3D association as studied by surface plasmon resonance assays. Supported by brownian dynamics simulations, our results show that a minimal encounter duration is required for 2D association; an energy landscape featuring a rough initial part might be a reasonable way of accounting for this. By systematically varying the temperature of our experiments, we evaluate roughness at 2k B T, in the range of previously proposed rough parts of landscapes models during dissociation.

Bispecific antibodies and trispecific immunocytokines for targeting the immune system against cancer: preparing for the future.

PubMed

Fournier, Philippe; Schirrmacher, Volker

2013-02-01

Monoclonal anti-tumor antibodies (mAbs) that are clinically effective usually recruit, via their constant fragment (Fc) domain, Fc receptor (FcR)-positive accessory cells of the immune system and engage these additionally against the tumor. Since T cells are FcR negative, these important cells are not getting involved. In contrast to mAbs, bispecific antibodies (bsAbs) can be designed in such a way that they involve T cells. bsAbs are artificially designed molecules that bind simultaneously to two different antigens, one on the tumor cell, the other one on an immune effector cell such as CD3 on T cells. Such dual antibody constructs can cross-link tumor cells and T cells. Many such bsAb molecules at the surface of tumor cells can thus build a bridge to T cells and aggregate their CD3 molecules, thereby activating them for cytotoxic activity. BsAbs can also contain a third binding site, for instance a Fc domain or a cytokine that would bind to its respective cytokine receptor. The present review discusses the pros and cons for the use of the Fc fragment during the development of bsAbs using either cell-fusion or recombinant DNA technologies. The recombinant antibody technology allows the generation of very efficient bsAbs containing no Fc domain such as the bi-specific T-cell engager (BiTE). The strong antitumor activity of these molecules makes them very interesting new cancer therapeutics. Over the last decade, we have developed another concept, namely to combine bsAbs and multivalent immunocytokines with a tumor cell vaccine. The latter are patient-derived tumor cells modified by infection with a virus. The virus-Newcastle Disease Virus (NDV)-introduces, at the surface of the tumor cells, viral molecules that can serve as general anchors for the bsAbs. Our strategy aims at redirecting, in an Fc-independent fashion, activities of T cells and accessory cells against autologous tumor antigens. It creates very promising perspectives for a new generation of efficient and safe cancer therapeutics that should confer long-lasting anti-tumor immunity.

Abseq: Ultrahigh-throughput single cell protein profiling with droplet microfluidic barcoding.

PubMed

Shahi, Payam; Kim, Samuel C; Haliburton, John R; Gartner, Zev J; Abate, Adam R

2017-03-14

Proteins are the primary effectors of cellular function, including cellular metabolism, structural dynamics, and information processing. However, quantitative characterization of proteins at the single-cell level is challenging due to the tiny amount of protein available. Here, we present Abseq, a method to detect and quantitate proteins in single cells at ultrahigh throughput. Like flow and mass cytometry, Abseq uses specific antibodies to detect epitopes of interest; however, unlike these methods, antibodies are labeled with sequence tags that can be read out with microfluidic barcoding and DNA sequencing. We demonstrate this novel approach by characterizing surface proteins of different cell types at the single-cell level and distinguishing between the cells by their protein expression profiles. DNA-tagged antibodies provide multiple advantages for profiling proteins in single cells, including the ability to amplify low-abundance tags to make them detectable with sequencing, to use molecular indices for quantitative results, and essentially limitless multiplexing.

Abseq: Ultrahigh-throughput single cell protein profiling with droplet microfluidic barcoding

NASA Astrophysics Data System (ADS)

Shahi, Payam; Kim, Samuel C.; Haliburton, John R.; Gartner, Zev J.; Abate, Adam R.

2017-03-01

Proteins are the primary effectors of cellular function, including cellular metabolism, structural dynamics, and information processing. However, quantitative characterization of proteins at the single-cell level is challenging due to the tiny amount of protein available. Here, we present Abseq, a method to detect and quantitate proteins in single cells at ultrahigh throughput. Like flow and mass cytometry, Abseq uses specific antibodies to detect epitopes of interest; however, unlike these methods, antibodies are labeled with sequence tags that can be read out with microfluidic barcoding and DNA sequencing. We demonstrate this novel approach by characterizing surface proteins of different cell types at the single-cell level and distinguishing between the cells by their protein expression profiles. DNA-tagged antibodies provide multiple advantages for profiling proteins in single cells, including the ability to amplify low-abundance tags to make them detectable with sequencing, to use molecular indices for quantitative results, and essentially limitless multiplexing.

Abseq: Ultrahigh-throughput single cell protein profiling with droplet microfluidic barcoding

PubMed Central

Shahi, Payam; Kim, Samuel C.; Haliburton, John R.; Gartner, Zev J.; Abate, Adam R.

2017-01-01

Proteins are the primary effectors of cellular function, including cellular metabolism, structural dynamics, and information processing. However, quantitative characterization of proteins at the single-cell level is challenging due to the tiny amount of protein available. Here, we present Abseq, a method to detect and quantitate proteins in single cells at ultrahigh throughput. Like flow and mass cytometry, Abseq uses specific antibodies to detect epitopes of interest; however, unlike these methods, antibodies are labeled with sequence tags that can be read out with microfluidic barcoding and DNA sequencing. We demonstrate this novel approach by characterizing surface proteins of different cell types at the single-cell level and distinguishing between the cells by their protein expression profiles. DNA-tagged antibodies provide multiple advantages for profiling proteins in single cells, including the ability to amplify low-abundance tags to make them detectable with sequencing, to use molecular indices for quantitative results, and essentially limitless multiplexing. PMID:28290550

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pak, J.; Sharon, C; Satkunarajah, M

The spike (S) protein of the severe acute respiratory syndrome coronavirus (SARS-CoV) is responsible for host cell attachment and fusion of the viral and host cell membranes. Within S the receptor binding domain (RBD) mediates the interaction with angiotensin-converting enzyme 2 (ACE2), the SARS-CoV host cell receptor. Both S and the RBD are highly immunogenic and both have been found to elicit neutralizing antibodies. Reported here is the X-ray crystal structure of the RBD in complex with the Fab of a neutralizing mouse monoclonal antibody, F26G19, elicited by immunization with chemically inactivated SARS-CoV. The RBD-F26G19 Fab complex represents the firstmore » example of the structural characterization of an antibody elicited by an immune response to SARS-CoV or any fragment of it. The structure reveals that the RBD surface recognized by F26G19 overlaps significantly with the surface recognized by ACE2 and, as such, suggests that F26G19 likely neutralizes SARS-CoV by blocking the virus-host cell interaction.« less

[Adult T-cell leukemia/lymphoma associated with unusual positivity of anti-ATLA (adult T-cell leukemia-cell-associated antigen) antibodies].

PubMed

Eto, T; Okamura, H; Okamura, T; Gondo, H; Kudo, J; Shibuya, T; Harada, M; Niho, Y

1990-03-01

A 56-year-old female was admitted because of generalized lymphadenopathy. Based upon histological findings of biopsied lymph node, malignant lymphoma, diffuse large cell type was diagnosed. The surface marker analysis showed that malignant cells were positive for CD4 and CD2 but negative for CD8. Although anti-ATLA (adult T-cell leukemia associated antigen) antibody was negative with the use of a gelatin particle agglutination method (P.A.), other methods such as an indirect immunofluorescence assay (I.F.), an enzyme-linked immunosorbent assay (E.I.A.) and a Western blotting assay revealed the positivity for anti-ATLA antibody. Adult T-cell leukemia/lymphoma (ATL/L) was confirmed by the presence of monoclonal integration of HTLV-I proviral DNA in biopsied specimen. This case, showing a pattern of P.A. (-) and I.F. (+), is extremely unusual, because I.F. and P.A. show highly close correlation. Thus, it is important to employ different methods for screening of anti-ATLA antibodies in the diagnosis of ATL/L.

Development of sugar chain-binding single-chain variable fragment antibody to adult T-cell leukemia cells using glyco-nanotechnology and phage display method.

PubMed

Muchima, Kaname; Todaka, Taro; Shinchi, Hiroyuki; Sato, Ayaka; Tazoe, Arisa; Aramaki, Rikiya; Kakitsubata, Yuhei; Yokoyama, Risa; Arima, Naomichi; Baba, Masanori; Wakao, Masahiro; Ito, Yuji; Suda, Yasuo

2018-04-01

Adult T-cell leukemia (ATL) is an intractable blood cancer caused by the infection of human T-cell leukemia virus type-1, and effective medical treatment is required. It is known that the structure and expression levels of cell surface sugar chains vary depending on cell states such as inflammation and cancer. Thus, it is expected that the antibody specific for ATL cell surface sugar chain would be an effective diagnostic tool and a strong candidate for the development of an anti-ATL drug. Here, we developed a stable sugar chain-binding single-chain variable fragment antibody (scFv) that can bind to ATL cells using a fibre-type Sugar Chip and phage display method. The fiber-type Sugar Chips were prepared using O-glycans released from ATL cell lines. The scFv-displaying phages derived from human B cells (diversity: 1.04 × 108) were then screened using the fiber-type Sugar Chips, and an O-glycan-binding scFv was obtained. The flow cytometry analysis revealed that the scFv predominantly bound to ATL cell lines. The sugar chain-binding properties of the scFv was evaluated by array-type Sugar Chip immobilized with a library of synthetic glycosaminoglycan disaccharide structures. Highly sulphated disaccharide structures were found to have high affinity to scFv.

The incomplete anti-Rh antibody agglutination mechanism of trypsinized ORh+ red cells.

PubMed Central

Margni, R A; Leoni, J; Bazzurro, M

1977-01-01

The capacity for binding to trypsinized and non-trypsinized ORh+ red cells, of the IgG incomplete anti-Rh antibody and its F(ab')2 and Fc fragments has been investigated. An analysis has also been made of the capacity of non-specific human IgG, aggregated non-specific human IgG, human IgM (19S) and IgM (7S), and of fragments Fcgamma, Fcmu and Fc5mu to inhibit the agglutination of trypsinized ORh+ red cells by the IgG incomplete anti-Rh antibody. The results obtained indicate that these antibodies behave in a similar manner to that of nonprecipitating antibodies, and that the agglutination of trypsinized red cells seems to be a mixed reaction due to the interaction of an Fab fragment with its Rh antigenic determinant present in the surface of a red cell and the Fc of the same molecule with a receptor for Fc present in adjacent red cells. The trypsin treatment apparently results in the liberation of occult Fc receptors. It has also been demonstrated that in the agglutination of ORh+ red cells by IgG incomplete anti-Rh antibody in the presence of albumin, interaction must occur in some manner between the albumin and the Fc fragment since the F(ab')2 fragment does not give rise to agglutination under such conditions. Images Figure 1 PMID:415968

Distinct mobilization of leukocytes and hematopoietic stem cells by CXCR4 peptide antagonist LY2510924 and monoclonal antibody LY2624587

PubMed Central

Peng, Sheng-Bin; Van Horn, Robert D.; Yin, Tinggui; Brown, Robin M.; Roell, William C.; Obungu, Victor H.; Ruegg, Charles; Wroblewski, Victor J.; Raddad, Eyas; Stille, John R.

2017-01-01

Stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4 play a critical role in mobilization and redistribution of immune cells and hematopoietic stem cells (HSCs). We evaluated effects of two CXCR4-targeting agents, peptide antagonist LY2510924 and monoclonal antibody LY2624587, on mobilizing HSCs and white blood cells (WBCs) in humans, monkeys, and mice. Biochemical analysis showed LY2510924 peptide blocked SDF-1/CXCR4 binding in all three species; LY2624587 antibody blocked binding in human and monkey, with minimal activity in mouse. Cellular analysis showed LY2624587 antibody, but not LY2510924 peptide, down-regulated cell surface CXCR4 and induced hematological tumor cell death; both agents have been shown to inhibit SDF-1/CXCR4 interaction and downstream signaling. In animal models, LY2510924 peptide induced robust, prolonged, dose- and time-dependent WBC and HSC increases in mice and monkeys, whereas LY2624587 antibody induced only moderate, transient increases in monkeys. In clinical trials, similar pharmacodynamic effects were observed in patients with advanced cancer: LY2510924 peptide induced sustained WBC and HSC increases, while LY2624587 antibody induced only minimal, transient WBC changes. These distinct pharmacodynamic effects in two different classes of CXCR4 inhibitors are clinically important and should be carefully considered when designing combination studies with immune checkpoint inhibitors or other agents for cancer therapy. PMID:29212254

Enzymatic cleavage of uracil-containing single-stranded DNA linkers for the efficient release of affinity-selected circulating tumor cells.

PubMed

Nair, Soumya V; Witek, Małgorzata A; Jackson, Joshua M; Lindell, Maria A M; Hunsucker, Sally A; Sapp, Travis; Perry, Caroline E; Hupert, Mateusz L; Bae-Jump, Victoria; Gehrig, Paola A; Wysham, Weiya Z; Armistead, Paul M; Voorhees, Peter; Soper, Steven A

2015-02-21

We report a novel strategy to enzymatically release affinity-selected cells, such as circulating tumor cells (CTCs), from surfaces with high efficiency (∼90%) while maintaining cell viability (>85%). The strategy utilizes single-stranded DNAs that link a capture antibody to the surfaces of a CTC selection device. The DNA linkers contain a uracil residue that can be cleaved.

A33 antibody-functionalized exosomes for targeted delivery of doxorubicin against colorectal Cancer.

PubMed

Li, Yan; Gao, Yuan; Gong, Chunai; Wang, Zhuo; Xia, Qingming; Gu, Fenfen; Hu, Chuling; Zhang, Lijuan; Guo, Huiling; Gao, Shen

2018-06-20

Exosomes have emerged as a promising drug carrier with low immunogenicity, high biocompatibility and delivery efficiency. Here in, we isolated exosomes from A33-positive LIM1215 cells (A33-Exo) and loaded them with doxorubicin (Dox). Furthermore, we coated surface-carboxyl superparamagnetic iron oxide nanoparticles (US) with A33 antibodies (A33Ab-US), expecting that these A33 antibodies on the surface of the nanoparticles could bind to A33-positive exosomes and form a complex (A33Ab-US-Exo/Dox) to target A33-positive colon cancer cells. The results showed that A33Ab-US-Exo/Dox had good binding affinity and antiproliferative effect in LIM1215 cells, as shown by increased uptake of the complex. In vivo study showed that A33Ab-US-Exo/Dox had an excellent tumor targeting ability, and was able to inhibit tumor growth and prolong the survival of the mice with reduced cardiotoxicity. In summary, exosomes functionalized by targeting ligands through coating with high-density antibodies may prove to be a novel delivery system for targeted drugs against human cancers. Copyright © 2018 Elsevier Inc. All rights reserved.

A murine monoclonal antibody directed against the carboxyl-terminal domain of GRP78 suppresses melanoma growth in mice.

PubMed

de Ridder, Gustaaf G; Ray, Rupa; Pizzo, Salvatore V

2012-06-01

The HSP70 family member GRP78 is a selective tumor marker upregulated on the surface of many tumor cell types, including melanoma, where it acts as a growth factor receptor-like protein. Receptor-recognized forms of the proteinase inhibitor α2-macroglobulin (α2M*) are the best-characterized ligands for GRP78, but in melanoma and other cancer patients, autoantibodies arise against the NH2-terminal domain of GRP78 that react with tumor cell-surface GRP78. This causes the activation of signaling cascades that are proproliferative and antiapoptotic. Antibodies directed against the COOH-terminal domain of GRP78, however, upregulate p53-mediated proapoptotic signaling, leading to cell death. Here, we describe the binding characteristics, cell signaling properties, and downstream cellular effects of three novel murine monoclonal antibodies. The NH2-terminal domain-reactive antibody, N88, mimics α2M* as a ligand and drives PI 3-kinase-dependent activation of Akt and the subsequent stimulation of cellular proliferation in vitro. The COOH-terminal domain-reactive antibody, C38, acts as an antagonist of both α2M* and N88, whereas another, C107, directly induces apoptosis in vitro. In a murine B16F1 melanoma flank tumor model, we demonstrate the acceleration of tumor growth by treatment with N88, whereas C107 significantly slowed tumor growth whether administered before (P<0.005) or after (P<0.05) tumor implantation.

Tumor dormancy and cell signaling. II. Antibody as an agonist in inducing dormancy of a B cell lymphoma in SCID mice.

PubMed

Racila, E; Scheuermann, R H; Picker, L J; Yefenof, E; Tucker, T; Chang, W; Marches, R; Street, N E; Vitetta, E S; Uhr, J W

1995-04-01

Tumor dormancy can be induced in a murine B cell lymphoma (BCL1) by immunizing BALB/c mice with the tumor immunoglobulin (Ig) before tumor cell challenge. In this report, we have investigated the immunological and cellular mechanisms underlying the induction of dormancy. BCL1 tumor cells were injected into SCID mice passively immunized with antibody against different epitopes on IgM or IgD with or without idiotype (Id)-immune T lymphocytes. Results indicate that antibody to IgM is sufficient to induce a state of dormancy. Antibodies against other cell surface molecules including IgD and CD44 (Pgp1) had no effect on tumor growth. Id-immune T cells by themselves also had no effect on tumor growth in SCID mice. However, simultaneous transfer of anti-Id and Id-immune T cells enhanced both the induction and duration of the dormant state. In vitro studies indicated that antibody to IgM induced apoptosis within several hours and cell cycle arrest by 24 h. Hyper cross-linking increased apoptosis. The Fc gamma RII receptor played little or no role in the negative signaling. Antibodies that did not negatively signal in vitro did not induce dormancy in vivo. The results suggest that anti-IgM plays a decisive role in inducing tumor dormancy to BCL1 by acting as an agonist of IgM-mediated signal transduction pathways.

Phenotyping and comparing the immune cell populations of free-ranging Atlantic bottlenose dolphins (Tursiops truncatus) and dolphins under human care.

PubMed

Nouri-Shirazi, Mahyar; Bible, Brittany F; Zeng, Menghua; Tamjidi, Saba; Bossart, Gregory D

2017-03-27

Studies suggest that free-ranging bottlenose dolphins exhibit a suppressed immune system because of exposure to contaminants or microorganisms. However, due to a lack of commercially available antibodies specific to marine mammal immune cell surface markers, the research has been indecisive. The purpose of this study was to identify cross-reactive terrestrial-specific antibodies in order to assess the changes in the immune cell populations of dolphins under human care and free-ranging dolphins. The blood and PBMC fraction of blood samples from human care and free-ranging dolphins were characterized by H&E staining of cytospin slides and flow cytometry using a panel of terrestrial-specific antibodies. In this study, we show that out of 65 terrestrial-specific antibodies tested, 11 were cross-reactive and identified dolphin immune cell populations within their peripheral blood. Using these antibodies, we found significant differences in the absolute number of cells expressing specific markers within their lymphocyte and monocyte fractions. Interestingly, the peripheral blood mononuclear cell profile of free-ranging dolphins retained an additional population of cells that divided them into two groups showing a low (<27%) or high (>56%) percentage of smaller cells resembling granulocytes. We found that the cross-reactive antibodies not only identified specific changes in the immune cells of free-ranging dolphins, but also opened the possibility to investigate the causal relationship between immunosuppression and mortality seen in free-ranging dolphins.

Clostridium perfringens Iota-Toxin: Mapping of Receptor Binding and Ia Docking Domains on Ib

PubMed Central

Marvaud, Jean-Christophe; Smith, Theresa; Hale, Martha L.; Popoff, Michel R.; Smith, Leonard A.; Stiles, Bradley G.

2001-01-01

Clostridium perfringens iota-toxin is a binary toxin consisting of iota a (Ia), an ADP-ribosyltransferase that modifies actin, and iota b (Ib), which binds to a cell surface protein and translocates Ia into a target cell. Fusion proteins of recombinant Ib and truncated variants were tested for binding to Vero cells and docking with Ia via fluorescence-activated cytometry and cytotoxicity experiments. C-terminal residues (656 to 665) of Ib were critical for cell surface binding, and truncated Ib variants containing ≥200 amino acids of the C terminus were effective Ib competitors and prevented iota cytotoxicity. The N-terminal domain (residues 1 to 106) of Ib was important for Ia docking, yet this region was not an effective competitor of iota cytotoxicity. Further studies showed that Ib lacking just the N-terminal 27 residues did not facilitate Ia entry into a target cell and subsequent cytotoxicity. Five monoclonal antibodies against Ib were also tested with each truncated Ib variant for epitope and structural mapping by surface plasmon resonance and an enzyme-linked immunosorbent assay. Each antibody bound to a linear epitope within the N terminus (residues 28 to 66) or the C terminus (residues 632 to 655). Antibodies that target the C terminus neutralized in vitro cytotoxicity and delayed the lethal effects of iota-toxin in mice. PMID:11254604

Development of Epitope-Focused Tumor Vaccine to Prevent Escape from Immune Surveillance by the NKG2D Pathway

DTIC Science & Technology

2017-12-01

each group), collecting the sera at weekly intervals and measuring the antibody titers by ELISA and flow cytometry. 2 October 2016 100 percent...collected at weekly intervals and was used for measuring the antibody titers by ELISA using the full length extracellular domain of MICA as capture...antibodies that bind to MICA on tumor cell surface. A. Elisa to determine the antibody titers in mice vaccinated with MICA vaccine consisting of 50µg

Immunization with recombinantly expressed glycan antigens from Schistosoma mansoni induces glycan-specific antibodies against the parasite

PubMed Central

Prasanphanich, Nina Salinger; Luyai, Anthony E; Song, Xuezheng; Heimburg-Molinaro, Jamie; Mandalasi, Msano; Mickum, Megan; Smith, David F; Nyame, A Kwame; Cummings, Richard D

2014-01-01

Schistosomiasis caused by infection with parasitic helminths of Schistosoma spp. is a major global health problem due to inadequate treatment and lack of a vaccine. The immune response to schistosomes includes glycan antigens, which could be valuable diagnostic markers and vaccine targets. However, no precedent exists for how to design vaccines targeting eukaryotic glycoconjugates. The di- and tri-saccharide motifs LacdiNAc (GalNAcβ1,4GlcNAc; LDN) and fucosylated LacdiNAc (GalNAcβ1,4(Fucα1-3)GlcNAc; LDNF) are the basis for several important schistosome glycan antigens. They occur in monomeric form or as repeating units (poly-LDNF) and as part of a variety of different glycoconjugates. Because chemical synthesis and conjugation of such antigens is exceedingly difficult, we sought to develop a recombinant expression system for parasite glycans. We hypothesized that presentation of parasite glycans on the cell surface would induce glycan-specific antibodies. We generated Chinese hamster ovary (CHO) Lec8 cell lines expressing poly-LDN (L8-GT) and poly-LDNF (L8-GTFT) abundantly on their membrane glycoproteins. Sera from Schistosoma mansoni-infected mice were highly cross-reactive with the cells and with cell-surface N-glycans. Immunizing mice with L8-GT and L8-GTFT cells induced glycan-specific antibodies. The L8-GTFT cells induced a sustained booster response, with antibodies that bound to S. mansoni lysates and recapitulated the exquisite specificity of the anti-parasite response for particular presentations of LDNF antigen. In summary, this recombinant expression system promotes successful generation of antibodies to the glycans of S. mansoni, and it can be adapted to study the role of glycan antigens and anti-glycan immune responses in many other infections and pathologies. PMID:24727440

Light-Guided Surface Engineering for Biomedical Applications

PubMed Central

Jayagopal, Ashwath; Stone, Gregory P.; Haselton, Frederick R.

2010-01-01

Free radical species generated through fluorescence photobleaching have been reported to effectively couple a water-soluble species to surfaces containing electron-rich sites (1). In this report, we expand upon this strategy to control the patterned attachment of antibodies and peptides to surfaces for biosensing and tissue engineering applications. In the first application, we compare hydrophobic attachment and photobleaching methods to immobilize FITC-labeled anti-M13K07 bacteriophage antibodies to the SiO2 layer of a differential capacitive biosensor and to the polyester filament of a feedback-controlled filament array. On both surfaces, antibody attachment and function were superior to the previously employed hydrophobic attachment. Furthermore, a laser scanning confocal microscope could be used for automated, software-guided photoattachment chemistry. In a second application, the cell-adhesion peptide RGDS was site-specifically photocoupled to glass coated with fluorescein-conjugated poly(ethylene glycol). RGDS attachment and bioactivity were characterized by a fibroblast adhesion assay. Cell adhesion was limited to sites of RGDS photocoupling. These examples illustrate that fluorophore-based photopatterning can be achieved by both solution-phase fluorophores or surface-adhered fluorophores. The coupling preserves the bioactivity of the patterned species, is amenable to a variety of surfaces, and is readily accessible to laboratories with fluorescence imaging equipment. The flexibility offered by visible light patterning will likely have many useful applications in bioscreening and tissue engineering where the controlled placement of biomolecules and cells is critical, and should be considered as an alternative to chemical coupling methods. PMID:18314938

Hydroxychloroquine protects the annexin A5 anticoagulant shield from disruption by antiphospholipid antibodies: evidence for a novel effect for an old antimalarial drug.

PubMed

Rand, Jacob H; Wu, Xiao-Xuan; Quinn, Anthony S; Ashton, Anthony W; Chen, Pojen P; Hathcock, James J; Andree, Harry A M; Taatjes, Douglas J

2010-03-18

Annexin A5 (AnxA5) is a potent anticoagulant protein that crystallizes over phospholipid bilayers (PLBs), blocking their availability for coagulation reactions. Antiphospholipid antibodies disrupt AnxA5 binding, thereby accelerating coagulation reactions. This disruption may contribute to thrombosis and miscarriages in the antiphospholipid syndrome (APS). We investigated whether the antimalarial drug, hydroxychloroquine (HCQ), might affect this prothrombotic mechanism. Binding of AnxA5 to PLBs was measured with labeled AnxA5 and also imaged with atomic force microscopy. Immunoglobulin G levels, AnxA5, and plasma coagulation times were measured on cultured human umbilical vein endothelial cells and a syncytialized trophoblast cell line. AnxA5 anticoagulant activities of APS patient plasmas were also determined. HCQ reversed the effect of antiphospholipid antibodies on AnxA5 and restored AnxA5 binding to PLBs, an effect corroborated by atomic force microscopy. Similar reversals of antiphospholipid-induced abnormalities were measured on the surfaces of human umbilical vein endothelial cells and syncytialized trophoblast cell lines, wherein HCQ reduced the binding of antiphospholipid antibodies, increased cell-surface AnxA5 concentrations, and prolonged plasma coagulation to control levels. In addition, HCQ increased the AnxA5 anticoagulant activities of APS patient plasmas. In conclusion, HCQ reversed antiphospholipid-mediated disruptions of AnxA5 on PLBs and cultured cells, and in APS patient plasmas. These results support the concept of novel therapeutic approaches that address specific APS disease mechanisms.

EpCAM-Independent Enrichment of Circulating Tumor Cells in Metastatic Breast Cancer.

PubMed

Schneck, Helen; Gierke, Berthold; Uppenkamp, Frauke; Behrens, Bianca; Niederacher, Dieter; Stoecklein, Nikolas H; Templin, Markus F; Pawlak, Michael; Fehm, Tanja; Neubauer, Hans

2015-01-01

Circulating tumor cells (CTCs) are the potential precursors of metastatic disease. Most assays established for the enumeration of CTCs so far-including the gold standard CellSearch-rely on the expression of the cell surface marker epithelial cell adhesion molecule (EpCAM). But, these approaches may not detect CTCs that express no/low levels of EpCAM, e.g. by undergoing epithelial-to-mesenchymal transition (EMT). Here we present an enrichment strategy combining different antibodies specific for surface proteins and extracellular matrix (ECM) components to capture an EpCAMlow/neg cell line and EpCAMneg CTCs from blood samples of breast cancer patients depleted for EpCAM-positive cells. The expression of respective proteins (Trop2, CD49f, c-Met, CK8, CD44, ADAM8, CD146, TEM8, CD47) was verified by immunofluorescence on EpCAMpos (e.g. MCF7, SKBR3) and EpCAMlow/neg (MDA-MB-231) breast cancer cell lines. To test antibodies and ECM proteins (e.g. hyaluronic acid (HA), collagen I, laminin) for capturing EpCAMneg cells, the capture molecules were first spotted in a single- and multi-array format onto aldehyde-coated glass slides. Tumor cell adhesion of EpCAMpos/neg cell lines was then determined and visualized by Coomassie/MitoTracker staining. In consequence, marginal binding of EpCAMlow/neg MDA-MB-231 cells to EpCAM-antibodies could be observed. However, efficient adhesion/capturing of EpCAMlow/neg cells could be achieved via HA and immobilized antibodies against CD49f and Trop2. Optimal capture conditions were then applied to immunomagnetic beads to detect EpCAMneg CTCs from clinical samples. Captured CTCs were verified/quantified by immunofluorescence staining for anti-pan-Cytokeratin (CK)-FITC/anti-CD45 AF647/DAPI. In total, in 20 out of 29 EpCAM-depleted fractions (69%) from 25 metastatic breast cancer patients additional EpCAMneg CTCs could be identified [range of 1-24 CTCs per sample] applying Trop2, CD49f, c-Met, CK8 and/or HA magnetic enrichment. EpCAMneg dual-positive (CKpos/CD45pos) cells could be traced in 28 out of 29 samples [range 1-480]. By single-cell array-based comparative genomic hybridization we were able to demonstrate the malignant nature of one EpCAMneg subpopulation. In conclusion, we established a novel enhanced CTC enrichment strategy to capture EpCAMneg CTCs from clinical blood samples by targeting various cell surface antigens with antibody mixtures and ECM components.

High-throughput screening of hybridoma supernatants using multiplexed fluorescent cell barcoding on live cells.

PubMed

Lu, Mei; Chan, Brian M; Schow, Peter W; Chang, Wesley S; King, Chadwick T

2017-12-01

With current available assay formats using either immobilized protein (ELISA, enzyme-linked immunosorbent assay) or immunostaining of fixed cells for primary monoclonal antibody (mAb) screening, researchers often fail to identify and characterize antibodies that recognize the native conformation of cell-surface antigens. Therefore, screening using live cells has become an integral and important step contributing to the successful identification of therapeutic antibody candidates. Thus the need for developing high-throughput screening (HTS) technologies using live cells has become a major priority for therapeutic mAb discovery and development. We have developed a novel technique called Multiplexed Fluorescent Cell Barcoding (MFCB), a flow cytometry-based method based upon the Fluorescent Cell Barcoding (FCB) technique and the Luminex fluorescent bead array system, but is applicable to high-through mAb screens on live cells. Using this technique in our system, we can simultaneously identify or characterize the antibody-antigen binding of up to nine unique fluorescent labeled cell populations in the time that it would normally take to process a single population. This has significantly reduced the amount of time needed for the identification of potential lead candidates. This new technology enables investigators to conduct large-scale primary hybridoma screens using flow cytometry. This in turn has allowed us to screen antibodies more efficiently than before and streamline identification and characterization of lead molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

Modulation of thymus-leukemia antigens on mouse leukemia cells induced by IgG, but not IgM, antibody.

PubMed

Stackpole, C W

1980-04-01

Exposure of mouse leukemia cells bearing thymus-leukemia (TL) surface antigens to whole TL alloantiserum has previously been shown to desensitize the cells to subsequent lysis by guinea pig complement (C) and fresh antiserum (antigenic modulation) and to correlate with the ability of cells to escape immune destruction in mice immunized against TL antigens. Tested in vitro, IgG of TL.1,2,3,5 antiserum modulated RADA1 leukemia cells (TL.1,2,3,5) completely within 2 hours at 37 degrees C when fully sensitizing amounts were used, with normal mouse serum as a source of C3. Similar results were obtained with IgG1, IgG2a, and IgG2b fractions of TL antiserum. An IgG2a monoclonal TL.3 antibody also completely modulated TL.3 antigens and partially modulated all antigens detected with TL.1,2,3,5 antiserum. IgM anti-TL.1,2,3,5 failed to modulate RADA1 cells even after 6 hours in vitro when fully sensitizing amounts of antibody were used. An IgM monoclonal TL antibody also failed to induce modulation. Modulation did occur on cells incubated with fully sensitizing amounts of IgG and IgM TL.1,2,3,5 antibody simultaneously, and nearly all cell-bound immunoglobulins were IgG. In mice passively immunized with IgG TL antibody, RADA1 cells modulated completely within 24 hours, whereas no modulation occurred during 4 days in mice immunized with IgM antibody. However, in both instances, tumor cells grew actively, which indicated that tumor escape did not depend on achievement of a modulated state.

Inhibition of the activity of cytotoxic murine T lymphocytes by antibodies to idiotypic determinants.

PubMed Central

Rabinowitz, R; Schlesinger, M

1980-01-01

The nature of the receptors on the surface of cytotoxic T lymphocytes (CTL), which enable these cells to recognize antigens on allogeneic targets, is still a matter of controversy. In the present study various mouse alloantisera were tested for their capacity to inhibit, in the absence of complement, the cytotoxic activity of sensitized peritoneal T lymphocytes. The only antiserum which, even after heat inactivation, consistently inhibited cytotoxic T lymphocytes was an antiserum elicited in (C3H X C57B1/6)F1 mice by immunization with AKR/Cum thymus cells. The serum inhibited the cytotoxic reaction of either AKR/J or AKR/Cum CTL on EL-4 target cells but had no inhibitory activity on the cytotoxic reaction of AKR/J cells against P-815 target cells. Thus the inhibitory activity of the serum could not be attributed to antibodies against Ly-3 determinants present in the serum. This conclusion was strengthened by the finding that the inhibitory activity of the serum could be removed by absorption, not only with AKR/J thymus cells but also with AKR/J bone-marrow cells, a procedure which did not affect the titre of Ly-3 antibodies. The serum failed to exert any inhibition on cytotoxic T lymphocytes of BALB/c and C3H mice reacting against EL-4 target cells, indicating that the inhibitory activity of the antiserum did not result from contamination by antibodies against C57B1 antigenic determinants. It was concluded that the inhibitory activity of the antiserum resulted from the presence of antibodies against idiotypic determinants expressed on AKR/Cum thymus cells reacting against the hybrid hosts. It seems, therefore, that idiotypic determinants expressed on the surface of cytotoxic T lymphocytes may be directly involved in their cytotoxic activity. PMID:6155324

Nanoyeast and Other Cell Envelope Compositions for Protein Studies and Biosensor Applications

PubMed Central

2016-01-01

Rapid progress in disease biomarker discovery has increased the need for robust detection technologies. In the past several years, the designs of many immunoaffinity reagents have focused on lowering costs and improving specificity while also promoting stability. Antibody fragments (scFvs) have long been displayed on the surface of yeast and phage libraries for selection; however, the stable production of such fragments presents challenges that hamper their widespread use in diagnostics. Membrane and cell wall proteins similarly suffer from stability problems when solubilized from their native environment. Recently, cell envelope compositions that maintain membrane proteins in native or native-like lipid environment to improve their stability have been developed. This cell envelope composition approach has now been adapted toward stabilizing antibody fragments by retaining their native cell wall environment. A new class of immunoaffinity reagents has been developed that maintains antibody fragment attachment to yeast cell wall. Herein, we review recent strategies that incorporate cell wall fragments with functional scFvs, which are designed for easy production while maintaining specificity and stability when in use with simple detection platforms. These cell wall based antibody fragments are globular in structure, and heterogeneous in size, with fragments ranging from tens to hundreds of nanometers in size. These fragments appear to retain activity once immobilized onto biosensor surfaces for the specific and sensitive detection of pathogen antigens. They can be quickly and economically generated from a yeast display library and stored lyophilized, at room temperature, for up to a year with little effect on stability. This new format of scFvs provides stability, in a simple and low-cost manner toward the use of scFvs in biosensor applications. The production and “panning” of such antibody cell wall composites are also extremely facile, enabling the rapid adoption of stable and inexpensive affinity reagents for emerging infectious threats. PMID:27762541

An efficient strategy for cell-based antibody library selection using an integrated vector system.

PubMed

Yoon, Hyerim; Song, Jin Myung; Ryu, Chun Jeih; Kim, Yeon-Gu; Lee, Eun Kyo; Kang, Sunghyun; Kim, Sang Jick

2012-09-18

Cell panning of phage-displayed antibody library is a powerful tool for the development of therapeutic and imaging agents since disease-related cell surface proteins in native complex conformation can be directly targeted. Here, we employed a strategy taking advantage of an integrated vector system which allows rapid conversion of scFv-displaying phage into scFv-Fc format for efficient cell-based scFv library selection on a tetraspanin protein, CD9. A mouse scFv library constructed by using a phagemid vector, pDR-D1 was subjected to cell panning against stable CD9 transfectant, and the scFv repertoire from the enriched phage pool was directly transferred to a mammalian cassette vector, pDR-OriP-Fc1. The resulting constructs enabled transient expression of enough amounts of scFv-Fcs in HEK293E cells, and flow cytometric screening of binders for CD9 transfectant could be performed simply by using the culture supernatants. All three clones selected from the screening showed correct CD9-specificity. They could immunoprecipitate CD9 molecules out of the transfectant cell lysate and correctly stain endogenous CD9 expression on cancer cell membrane. Furthermore, competition assay with a known anti-CD9 monoclonal antibody (mAb) suggested that the binding epitopes of some of them overlap with that of the mAb which resides within the large extracellular loop of CD9. This study demonstrates that scFv-Fc from mammalian transient expression can be chosen as a reliable format for rapid screening and validation in cell-based scFv library selection, and the strategy described here will be applicable to efficient discovery of antibodies to diverse cell-surface targets.

Common tree shrews and primates share leukocyte membrane antigens.

PubMed

Palley, L S; Schlossman, S F; Letvin, N L

1984-01-01

Monoclonal antibodies reactive with human peripheral blood lymphocyte and myeloid cell surface antigens were utilized to study the phylogeny of the common tree shrew. Blood cells from the common tree shrew, but not the bat or short-tailed shrew, react with certain of these antibodies. These data strengthen the argument that the Tupaiidae are primitive primates rather than insectivores. They also indicate that this approach should be useful for further work in taxonomic systemization.

Nanovectors for Targeting and Delivery of Therapeutics to HER-2 NEU Positive Breast Cancer Cells

DTIC Science & Technology

2008-10-01

Staphylococcus aureus induces hyperadhesiveness for human monocytes and granulocytes. J.Immunol. 158 (1997) 774-782. [19] Ibrahim, A. S., Spellberg, B...antibodies (or aptamers ) attached to the first stage of the delivery vector. Markers with increased expression on the surface of tumor cells, such as...with second-stage iron oxide nanoparticles. As stated previously, HER2-conjugated iron oxide nanoparticles and VEGFR-2 antibody (or aptamer

Visualization of the membrane engineering concept: evidence for the specific orientation of electroinserted antibodies and selective binding of target analytes.

PubMed

Kokla, Anna; Blouchos, Petros; Livaniou, Evangelia; Zikos, Christos; Kakabakos, Sotiris E; Petrou, Panagiota S; Kintzios, Spyridon

2013-12-01

Membrane engineering is a generic methodology for increasing the selectivity of a cell biosensor against a target molecule, by electroinserting target-specific receptor-like molecules on the cell surface. Previous studies have elucidated the biochemical aspects of the interaction between various analytes (including viruses) and their homologous membrane-engineered cells. In the present study, purified anti-biotin antibodies from a rabbit antiserum along with in-house prepared biotinylated bovine serum albumin (BSA) were used as a model antibody-antigen pair of molecules for facilitating membrane engineering experiments. It was proven, with the aid of fluorescence microscopy, that (i) membrane-engineered cells incorporated the specific antibodies in the correct orientation and that (ii) the inserted antibodies are selectively interacting with the homologous target molecules. This is the first time the actual working concept of membrane engineering has been visualized, thus providing a final proof of the concept behind this innovative process. In addition, the fluorescence microscopy measurements were highly correlated with bioelectric measurements done with the aid of a bioelectric recognition assay. Copyright © 2013 John Wiley & Sons, Ltd.

Cancer Immunotherapy Using Virus-like Particles | NCI Technology Transfer Center | TTC

Cancer.gov

A considerable effort has been devoted to identifying and targeting specific extracellular cancer markers using antibody based therapies. However, diminished access to new cancer cell surface markers has limited the development of corresponding antibodies. NCI Technology Transfer Center is seeking to license cancer immunotherapy using virus-like particles.

The Escherichia coli Subtilase Cytotoxin A Subunit Specifically Cleaves Cell-surface GRP78 Protein and Abolishes COOH-terminal-dependent Signaling

PubMed Central

Ray, Rupa; de Ridder, Gustaaf G.; Eu, Jerry P.; Paton, Adrienne W.; Paton, James C.; Pizzo, Salvatore V.

2012-01-01

GRP78, a molecular chaperone with critical endoplasmic reticulum functions, is aberrantly expressed on the surface of cancer cells, including prostate and melanoma. Here it functions as a pro-proliferative and anti-apoptotic signaling receptor via NH2-terminal domain ligation. Auto-antibodies to this domain may appear in cancer patient serum where they are a poor prognostic indicator. Conversely, GRP78 COOH-terminal domain ligation is pro-apoptotic and anti-proliferative. There is no method to disrupt cell-surface GRP78 without compromising the total GRP78 pool, making it difficult to study cell-surface GRP78 function. We studied six cell lines representing three cancer types. One cell line per group expresses high levels of cell-surface GRP78, and the other expresses low levels (human hepatoma: Hep3B and HepG2; human prostate cancer: PC3 and 1-LN; murine melanoma: B16F0 and B16F1). We investigated the effect of Escherichia coli subtilase cytoxin catalytic subunit (SubA) on GRP78. We report that SubA specifically cleaves cell-surface GRP78 on HepG2, 1-LN, and B16F1 cells without affecting intracellular GRP78. B16F0 cells (GRP78low) have lower amounts of cleaved cell-surface GRP78. SubA has no effect on Hep3B and PC3 cells. The predicted 28-kDa GRP78 COOH-terminal fragment is released into the culture medium by SubA treatment, and COOH-terminal domain signal transduction is abrogated, whereas pro-proliferative signaling mediated through NH2-terminal domain ligation is unaffected. These experiments clarify cell-surface GRP78 topology and demonstrate that the COOH-terminal domain is necessary for pro-apoptotic signal transduction occurring upon COOH-terminal antibody ligation. SubA is a powerful tool to specifically probe the functions of cell-surface GRP78. PMID:22851173

The Escherichia coli subtilase cytotoxin A subunit specifically cleaves cell-surface GRP78 protein and abolishes COOH-terminal-dependent signaling.

PubMed

Ray, Rupa; de Ridder, Gustaaf G; Eu, Jerry P; Paton, Adrienne W; Paton, James C; Pizzo, Salvatore V

2012-09-21

GRP78, a molecular chaperone with critical endoplasmic reticulum functions, is aberrantly expressed on the surface of cancer cells, including prostate and melanoma. Here it functions as a pro-proliferative and anti-apoptotic signaling receptor via NH(2)-terminal domain ligation. Auto-antibodies to this domain may appear in cancer patient serum where they are a poor prognostic indicator. Conversely, GRP78 COOH-terminal domain ligation is pro-apoptotic and anti-proliferative. There is no method to disrupt cell-surface GRP78 without compromising the total GRP78 pool, making it difficult to study cell-surface GRP78 function. We studied six cell lines representing three cancer types. One cell line per group expresses high levels of cell-surface GRP78, and the other expresses low levels (human hepatoma: Hep3B and HepG2; human prostate cancer: PC3 and 1-LN; murine melanoma: B16F0 and B16F1). We investigated the effect of Escherichia coli subtilase cytoxin catalytic subunit (SubA) on GRP78. We report that SubA specifically cleaves cell-surface GRP78 on HepG2, 1-LN, and B16F1 cells without affecting intracellular GRP78. B16F0 cells (GRP78(low)) have lower amounts of cleaved cell-surface GRP78. SubA has no effect on Hep3B and PC3 cells. The predicted 28-kDa GRP78 COOH-terminal fragment is released into the culture medium by SubA treatment, and COOH-terminal domain signal transduction is abrogated, whereas pro-proliferative signaling mediated through NH(2)-terminal domain ligation is unaffected. These experiments clarify cell-surface GRP78 topology and demonstrate that the COOH-terminal domain is necessary for pro-apoptotic signal transduction occurring upon COOH-terminal antibody ligation. SubA is a powerful tool to specifically probe the functions of cell-surface GRP78.

Sers Imaging of Nasopharyngeal Carcinoma Markers Using an Antibody-Conjugated Gold Nanoparticles Probe

NASA Astrophysics Data System (ADS)

Li, J.-H.; Du, Y.; Feng, G.-K.; Du, Y.-B.; Zhou, Y.-Q.; Zeng, M.-S.

2017-11-01

Surface-enhanced Raman scattering (SERS) nanotags as an ultrasensitive nanoprobe is becoming popular for the detection of biomarkers. Herein, antibody-conjugated gold nanoparticles (AuNPs) were used to target LMP2A in an LMP2A-infected CNE2 cell line. SERS maps showed that the LMP2A was distributed around the cell, which was consistent with the results of immunofl uorescence staining in the previous report. This location could be due to the specific binding of the bioconjugated nanotags to the receptors on the cell surface. However, the CNE2 cell line without LMP2A-infected showed no detectable signal at 1044 cm-1. The results demonstrated the potential feasibility of AuNPs nanotags as highly sensitive probes conjugated at the subcellular level for detection and localization of cancer markers in nasopharyngeal carcinoma (NPC).

The PD-1/PD-L1 complex resembles the antigen-binding Fv domains of antibodies and T cell receptors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, David Yin-wei; Tanaka, Yoshimasa; Iwasaki, Masashi

2008-07-29

Signaling through the programmed death 1 (PD-1) inhibitory receptor upon binding its ligand, PD-L1, suppresses immune responses against autoantigens and tumors and plays an important role in the maintenance of peripheral immune tolerance. Release from PD-1 inhibitory signaling revives 'exhausted' virus-specific T cells in chronic viral infections. Here we present the crystal structure of murine PD-1 in complex with human PD-L1. PD-1 and PD-L1 interact through the conserved front and side of their Ig variable (IgV) domains, as do the IgV domains of antibodies and T cell receptors. This places the loops at the ends of the IgV domains onmore » the same side of the PD-1/PD-L1 complex, forming a surface that is similar to the antigen-binding surface of antibodies and T cell receptors. Mapping conserved residues allowed the identification of residues that are important in forming the PD-1/PD-L1 interface. Based on the structure, we show that some reported loss-of-binding mutations involve the PD-1/PD-L1 interaction but that others compromise protein folding. The PD-1/PD-L1 interaction described here may be blocked by antibodies or by designed small-molecule drugs to lower inhibitory signaling that results in a stronger immune response. The immune receptor-like loops offer a new surface for further study and potentially the design of molecules that would affect PD-1/PD-L1 complex formation and thereby modulate the immune response.« less

Large-scale sequence and structural comparisons of human naive and antigen-experienced antibody repertoires

PubMed Central

DeKosky, Brandon J.; Lungu, Oana I.; Park, Daechan; Johnson, Erik L.; Charab, Wissam; Chrysostomou, Constantine; Kuroda, Daisuke; Ellington, Andrew D.; Ippolito, Gregory C.; Gray, Jeffrey J.; Georgiou, George

2016-01-01

Elucidating how antigen exposure and selection shape the human antibody repertoire is fundamental to our understanding of B-cell immunity. We sequenced the paired heavy- and light-chain variable regions (VH and VL, respectively) from large populations of single B cells combined with computational modeling of antibody structures to evaluate sequence and structural features of human antibody repertoires at unprecedented depth. Analysis of a dataset comprising 55,000 antibody clusters from CD19+CD20+CD27− IgM-naive B cells, >120,000 antibody clusters from CD19+CD20+CD27+ antigen–experienced B cells, and >2,000 RosettaAntibody-predicted structural models across three healthy donors led to a number of key findings: (i) VH and VL gene sequences pair in a combinatorial fashion without detectable pairing restrictions at the population level; (ii) certain VH:VL gene pairs were significantly enriched or depleted in the antigen-experienced repertoire relative to the naive repertoire; (iii) antigen selection increased antibody paratope net charge and solvent-accessible surface area; and (iv) public heavy-chain third complementarity-determining region (CDR-H3) antibodies in the antigen-experienced repertoire showed signs of convergent paired light-chain genetic signatures, including shared light-chain third complementarity-determining region (CDR-L3) amino acid sequences and/or Vκ,λ–Jκ,λ genes. The data reported here address several longstanding questions regarding antibody repertoire selection and development and provide a benchmark for future repertoire-scale analyses of antibody responses to vaccination and disease. PMID:27114511

THE AP-2 CLATHRIN ADAPTOR MEDIATES ENDOCYTOSIS OF AN INHIBITORY KILLER CELL Ig-LIKE RECEPTOR (KIR) IN HUMAN NK CELLS1

PubMed Central

Purdy, Amanda K.; Alvarez-Arias, Diana A.; Oshinsky, Jennifer; James, Ashley M.; Serebriiskii, Ilya; Campbell, Kerry S.

2014-01-01

Stable surface expression of human inhibitory killer cell immunoglobulin-like receptors (KIR) is critical for controlling NK cell function and maintaining NK cell tolerance toward normal MHC-I+ cells. Our recent experiments, however, have found that antibody-bound KIR3DL1 (3DL1) readily leaves the cell surface and undergoes endocytosis to early/recycling endosomes and subsequently to late endosomes. We found that 3DL1 internalization is at least partially mediated by an interaction between the μ2 subunit of the AP-2 clathrin adaptor complex and ITIM tyrosine residues in the cytoplasmic domain of 3DL1. Disruption of the 3DL1/μ2 interaction, either by mutation of the ITIM tyrosines in 3DL1 or mutation of μ2, significantly diminished endocytosis and increased surface expression of 3DL1 in human primary NK cells and cell lines. Furthermore, we found that the 3DL1/AP-2 interaction is diminished upon antibody engagement with the receptor, as compared to untreated cells. Thus, we have identified AP-2-mediated endocytosis as a mechanism regulating the surface levels of inhibitory KIR though their ITIM domains. Based upon our results, we propose a model in which non-engaged KIR are internalized by this mechanism, whereas engagement with MHC-I ligand would diminish AP-2 binding, thereby prolonging stable receptor surface expression and promoting inhibitory function. Furthermore, this ITIM-mediated mechanism may similarly regulate the surface expression of other inhibitory immune receptors. PMID:25238755

Lipoteichoic acids are embedded in cell walls during logarithmic phase, but exposed on membrane vesicles in Lactobacillus gasseri JCM 1131T.

PubMed

Shiraishi, T; Yokota, S; Sato, Y; Ito, T; Fukiya, S; Yamamoto, S; Sato, T; Yokota, A

2018-06-15

Lipoteichoic acid (LTA) is a cell surface molecule specific to Gram-positive bacteria. How LTA localises on the cell surface is a fundamental issue in view of recognition and immunomodulation in hosts. In the present study, we examined LTA localisation using strain JCM 1131T of Lactobacillus gasseri, which is a human intestinal lactic acid bacterium, during various growth phases by immunoelectron microscopy. We first evaluated the specificity of anti-LTA monoclonal antibody clone 55 used as a probe. The glycerophosphate backbone comprising almost intact size (20 to 30 repeating units) of LTA was required for binding. The antibody did not bind to other cellular components, including wall-teichoic acid. Immunoelectron microscopy indicated that LTA was embedded in the cell wall during the logarithmic phase, and was therefore not exposed on the cell surface. Similar results were observed for Lactobacillus fermentum ATCC 9338 and Lactobacillus rhamnosus ATCC 7469T. By contrast, membrane vesicles were observed in the logarithmic phase of L. gasseri with LTA exposed on their surface. In the stationary and death phases, LTA was exposed on cell wall-free cell membrane generated by autolysis. The dramatic alternation of localisation in different growth phases and exposure on the surface of membrane vesicles should relate with complicated interaction between bacteria and host.

Reversible Opening of the Blood-Brain Barrier by Anti-Bacterial Antibodies

NASA Astrophysics Data System (ADS)

Tuomanen, Elaine I.; Prasad, Sudha M.; George, Jonathan S.; Hoepelman, Andy I. M.; Ibsen, Per; Heron, Iver; Starzyk, Ruth M.

1993-08-01

The leukocyte adhesion molecule CR3 (CD11b/CD18, Mac-1) promotes leukocyte transmigration into tissues by engaging an unknown cognate ligand on the surface of vascular endothelial cells. Filamentous hemagglutinin (FHA), an adhesin of the bacterium Bordetella pertussis, binds to CR3. We hypothesized that FHA mimics the native ligand for the CR3 integrin on endothelial cells and predicted that anti-FHA antibodies should bind to endothelial cells, interfere with leukocyte recruitment, and induce endothelial permeability. Anti-FHA monoclonal antibodies bound to cerebral microvessels in sections from human brain and upon intravenous injection into rabbits. Antibody binding correlated with the ability to recognize two polypeptides in extracts of human cerebral vessels that were also bound by CD18. In vivo, antibody binding not only interfered with transmigration of leukocytes into cerebrospinal fluid but also induced a dose-dependent reversible increase in blood-brain barrier permeability sufficient to improve delivery of intravenously administered therapeutic agents to brain parenchyma.

Electro-optical study of the exposure of Azospirillum brasilense carbohydrate epitopes.

PubMed

Guliy, Olga I; Matora, Larisa Yu; Dykman, Lev A; Staroverov, Sergey A; Burygin, Gennady L; Bunin, Viktor D; Burov, Andrei M; Ignatov, Oleg V

2015-01-01

The exposure of Azospirillum brasilense carbohydrate epitopes was investigated by electro-optical analysis of bacterial cell suspensions. To study changes in the electro-optical (EO) properties of the suspensions, we used antibodies generated to the complete lipopolysaccharide of A. brasilense type strain Sp7 and also antibodies to the smooth and rough O polysaccharides of Sp7. After 18 hr of culture growth, the EO signal of the suspension treated with antibodies to smooth O polysaccharide was approximately 20% lower than that of the suspension treated with antibodies to complete lipopolysaccharide (control). After 72 hr of culture growth, the strongest EO signal was observed for the cells treated with antibodies to rough O polysaccharide (approximately 46% greater than the control), whereas for the cells treated with antibodies to smooth O polysaccharide, it was much lower (approximately 23% of the control). These data were confirmed by electron microscopy. The results of the study may have importance for the rapid evaluation of changes in lipopolysaccharide form in microbial biotechnology, when the antigenic composition of the bacterial surface requires close control.

Mouse monoclonal antibodies against human c-Mpl and characterization for flow cytometry applications.

PubMed

Abbott, Christina; Huang, Guo; Ellison, Aaron R; Chen, Ching; Arora, Taruna; Szilvassy, Stephen J; Wei, Ping

2010-04-01

Mouse monoclonal antibodies (MAbs) against human c-Mpl, the cognate receptor for thrombopoietin (TPO), were generated using hybridoma technology and characterized by various assays to demonstrate their specificity and affinity. Two such MAbs, 1.6 and 1.75, were determined to be superior for flow cytometry studies and exhibited double-digit picomolar (pM) affinities to soluble human c-Mpl protein. Both MAbs specifically bound to cells engineered to overexpress human c-Mpl protein, immortalized human hematopoietic cell lines that express endogenous c-Mpl, primary human bone marrow and peripheral blood-derived CD34(+) cells, and purified human platelets. No binding was detected on cell lines that did not express c-Mpl. Receptor competition and siRNA knock-down studies further confirmed the specificity of antibodies 1.6 and 1.75 for human c-Mpl. In contrast to these newly generated MAbs, none of eight commercially available anti-c-Mpl antibodies tested were found to bind specifically to human c-Mpl and were thus shown to be unsuitable for flow cytometry studies. Monoclonal antibodies 1.6 and 1.75 will therefore be useful flow cytometry reagents to detect cell surface c-Mpl expression.

Antibody targeting of anaplastic lymphoma kinase induces cytotoxicity of human neuroblastoma

PubMed Central

Carpenter, EL; Haglund, EA; Mace, EM; Deng, D; Martinez, D; Wood, AC; Chow, AK; Weiser, DA; Belcastro, LT; Winter, C; Bresler, SC; Asgharzadeh, S; Seeger, RC; Zhao, H; Guo, R; Christensen, JG; Orange, JS; Pawel, BR; Lemmon, MA; Mossé, YP

2013-01-01

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase aberrantly expressed in neuroblastoma, a devastating pediatric cancer of the sympathetic nervous system. Germline and somatically acquired ALK aberrations induce increased autophosphorylation, constitutive ALK activation and increased downstream signaling. Thus, ALK is a tractable therapeutic target in neuroblastoma, likely to be susceptible to both small-molecule tyrosine kinase inhibitors and therapeutic antibodies–as has been shown for other receptor tyrosine kinases in malignancies such as breast and lung cancer. Small-molecule inhibitors of ALK are currently being studied in the clinic, but common ALK mutations in neuroblastoma appear to show de novo insensitivity, arguing that complementary therapeutic approaches must be developed. We therefore hypothesized that antibody targeting of ALK may be a relevant strategy for the majority of neuroblastoma patients likely to have ALK-positive tumors. We show here that an antagonistic ALK antibody inhibits cell growth and induces in vitro antibody-dependent cellular cytotoxicity of human neuroblastoma-derived cell lines. Cytotoxicity was induced in cell lines harboring either wild type or mutated forms of ALK. Treatment of neuroblastoma cells with the dual Met/ALK inhibitor crizotinib sensitized cells to antibody-induced growth inhibition by promoting cell surface accumulation of ALK and thus increasing the accessibility of antigen for antibody binding. These data support the concept of ALK-targeted immunotherapy as a highly promising therapeutic strategy for neuroblastomas with mutated or wild-type ALK. PMID:22266870

Built-in adjuvanticity of genetically and protein-engineered chimeric molecules for targeting of influenza A peptide epitopes.

PubMed

Kerekov, Nikola S; Ivanova, Iva I; Mihaylova, Nikolina M; Nikolova, Maria; Prechl, Jozsef; Tchorbanov, Andrey I

2014-10-01

Highly purified, subunit, or synthetic viral antigens are known to be weakly immunogenic and potentate only the antibody, rather than cell-mediated immune responses. An alternative approach for inducing protective immunity with small viral peptides would be the direct targeting of viral epitopes to the immunocompetent cells by DNA vaccines encoding antibody fragments specific to activating cell surface co-receptor molecules. Here, we are exploring as a new genetic vaccine, a DNA chimeric molecule encoding a T and B cell epitope-containing influenza A virus hemagglutinin peptide joined to sequences encoding a single-chain variable fragment antibody fragment specific for the costimulatory B cell complement receptors 1 and 2. This recombinant DNA molecule was inserted into eukaryotic expression vector and used as a naked DNA vaccine in WT and CR1/2 KO mice. The intramuscular administration of the DNA construct resulted in the in vivo expression of an immunogenic chimeric protein, which cross-links cell surface receptors on influenza-specific B cells. The DNA vaccination was followed by prime-boosting with the protein-engineered replica of the DNA construct, thus delivering an activation intracellular signal. Immunization with an expression vector containing the described construct and boosting with the protein chimera induced a strong anti-influenza cytotoxic response, modulation of cytokine profile, and a weak antibody response in Balb/c mice. The same immunization scheme did not result in generation of influenza-specific response in mice lacking the target receptor, underlining the molecular adjuvant effect of receptor targeting.

The interaction in vitro of Mycoplasma pulmonis with mouse peritoneal macrophages and L-cells.

PubMed

Jones, T C; Hirsch, J G

1971-02-01

Methods have been devised for establishing infection in vitro of mouse macrophages and fibroblasts with Mycoplasma pulmonis. The mycoplasmas attached to the cells and under appropriate cultural conditions grew into a lawn of microorganisms covering most of the cell surface. The mycoplasmas grew abundantly on fibroblasts cultured in minimal essential medium containing 20% fetal calf serum; supplementation of this medium with heart infusion broth was necessary to obtain similar growth on macrophages. The infection of these cells appeared to be essentially an extracellular process; only rarely were partially degraded mycoplasmas seen with phagocytic vacuoles. The addition to heavily infected macrophage cultures of low concentrations of anti-mycoplasma antibody stimulated rapid, massive phagocytosis of the surface microorganisms. In sharp contrast, the same antiserum had no discernable effect on the mycoplasma-fibroblast relationship. The antibody effect in the macrophage system was apparently a direct opsonic one rather than an indirect result of microbial killing, since the mycoplasmas in macrophage or fibroblast cultures incorporated labelled thymidine into DNA after the addition of antiserum to the medium. The phagocytic event and the subsequent fate of the mycoplasmas were studied in detail after the addition of antibody to the macrophage cultures. Phase-contrast cinemicrophotography revealed membrane ruffles surrounding the surface mycoplasmas and disappearance from view of the organisms; 10-30 min later translucent grapelike clusters were seen in large phagocytic vacuoles. On electronmicroscopic study the surface mycoplasmas were surrounded by pincers-like projections of the macrophage. Numerous mycoplasmas were seen in phagocytic vacuoles; in the early minutes after the addition of antibody the intracellular mycoplasmas appeared normal, but within 2 hr they appeared partially degraded with a central electron-lucent area and electron-opaque deposits at the microbial cell margin. 24 hr after the addition of antiserum, digestion of the mycoplasmas was nearly complete; the cells appeared normal except for large residual bodies composed of amorphous moderately dense material and increased lipid deposits. Degradation of mycoplasmas within macrophages was also studied using infected cultures in which the mycoplasmas, but not the macrophages, had incorporated tritiated thymidine into DNA. The appearance of large amounts of acid-soluble radiolabel after phagocytosis stimulated by antibody confirmed the degradation of the intracellular mycoplasmas.

Anti‐CD22 and anti‐CD79b antibody‐drug conjugates preferentially target proliferating B cells

PubMed Central

Fuh, Franklin K; Looney, Caroline; Li, Dongwei; Poon, Kirsten A; Dere, Randall C; Danilenko, Dimitry M; McBride, Jacqueline; Reed, Chae; Chung, Shan; Zheng, Bing; Mathews, William Rodney; Polson, Andrew; Williams, Marna

2017-01-01

Background and Purpose CD22 and CD79b are cell‐surface receptors expressed on B‐cell‐derived malignancies such as non‐Hodgkin's lymphoma (NHL). An anti‐mitotic agent, monomethyl auristatin E, was conjugated to anti‐CD22 and anti‐CD79b antibodies to develop target‐specific therapies for NHL. The mechanism of action (MOA) and pharmacological and pharmacokinetic (PK) profiles of these antibody‐drug conjugates (ADCs) were investigated in cynomolgus monkeys. Experimental Approach Animals were administered anti‐CD22 or anti‐CD79b ADCs, respective unconjugated antibodies or vehicle. Pharmacodynamic effects on total and proliferating B cells and serum PK were then assessed. Antibody‐dependent cellular cytotoxicity (ADCC) and complement‐dependent cytotoxicity (CDC) of the ADCs were evaluated in vitro. Key Results Depletion of B cells was observed after administration of either ADC or the respective unconjugated antibodies. An extended duration of depletion was observed in animals administered ADCs. Similarly, preferential depletion of proliferating B cells in blood and germinal centre B cells in spleen were only observed in animals administered ADCs. Serum PK profiles of ADCs and respective unconjugated antibodies were comparable. In vitro, anti‐human CD22 and anti‐human CD79b antibodies showed no or only moderate ADCC activity, respectively; neither antibody had CDC activity. Conclusions and Implications The findings support the proposed MOA: initial depletion of total B cells by antibody‐mediated opsonization, followed by preferential, sustained depletion of proliferating B cells by the auristatin conjugate due to its anti‐mitotic action. Delivering potent anti‐mitotic agents to B cells via the specificity of monoclonal antibodies provides a means to eliminate pathogenic B cells in NHL with improved risk–benefit profiles over traditional chemotherapeutics. PMID:28009435

Isolation of recombinant antibodies directed against surface proteins of Clostridium difficile.

PubMed

Shirvan, Ali Nazari; Aitken, Robert

2016-01-01

Clostridium difficile has emerged as an increasingly important nosocomial pathogen and the prime causative agent of antibiotic-associated diarrhoea and pseudomembranous colitis in humans. In addition to toxins A and B, immunological studies using antisera from patients infected with C. difficile have shown that a number of other bacterial factors contribute to the pathogenesis, including surface proteins, which are responsible for adhesion, motility and other interactions with the human host. In this study, various clostridial targets, including FliC, FliD and cell wall protein 66, were expressed and purified. Phage antibody display yielded a large panel of specific recombinant antibodies, which were expressed, purified and characterised. Reactions of the recombinant antibodies with their targets were detected by enzyme-linked immunosorbent assay; and Western blotting suggested that linear rather than conformational epitopes were recognised. Binding of the recombinant antibodies to surface-layer proteins and their components showed strain specificity, with good recognition of proteins from C. difficile 630. However, no reaction was observed for strain R20291-a representative of the 027 ribotype. Binding of the recombinant antibodies to C. difficile M120 extracts indicated that a component of a surface-layer protein of this strain might possess immunoglobulin-binding activities. The recombinant antibodies against FliC and FliD proteins were able to inhibit bacterial motility. Copyright © 2016. Published by Elsevier Editora Ltda.

Principles of antibody-mediated TNF receptor activation

PubMed Central

Wajant, H

2015-01-01

From the beginning of research on receptors of the tumor necrosis factor (TNF) receptor superfamily (TNFRSF), agonistic antibodies have been used to stimulate TNFRSF receptors in vitro and in vivo. Indeed, CD95, one of the first cloned TNFRSF receptors, was solely identified as the target of cell death-inducing antibodies. Early on, it became evident from in vitro studies that valency and Fcγ receptor (FcγR) binding of antibodies targeting TNFRSF receptors can be of crucial relevance for agonistic activity. TNFRSF receptor-specific antibodies of the IgM subclass and secondary cross-linked or aggregation prone dimeric antibodies typically display superior agonistic activity compared with dimeric antibodies. Likewise, anchoring of antibodies to cell surface-expressed FcγRs potentiate their ability to trigger TNFRSF receptor signaling. However, only recently has the relevance of oligomerization and FcγR binding for the in vivo activity of antibody-induced TNFRSF receptor activation been straightforwardly demonstrated in vivo. This review discusses the crucial role of oligomerization and/or FcγR binding for antibody-mediated TNFRSF receptor stimulation in light of current models of TNFRSF receptor activation and especially the overwhelming relevance of these issues for the rational development of therapeutic TNFRSF receptor-targeting antibodies. PMID:26292758

Human IgG1 antibodies antagonizing activating receptor NKG2D on natural killer cells

PubMed Central

Steigerwald, Jutta; Raum, Tobias; Pflanz, Stefan; Cierpka, Ronny; Mangold, Susanne; Rau, Doris; Hoffmann, Patrick; Kvesic, Majk; Zube, Christina; Linnerbauer, Stefanie; Lumsden, John; Sriskandarajah, Mirnaalini; Kufer, Peter; Baeuerle, Patrick A

2009-01-01

NKG2D is a surface receptor expressed on NK cells but also on CD8+ T cells, γδ T cells, and auto-reactive CD4+/CD28− T cells of patients with rheumatoid arthritis. Various studies suggested that NKG2D plays a critical role in autoimmune diseases, e.g., in diabetes, celiac disease and rheumatoid arthritis (RA), rendering the activating receptor a potential target for antibody-based therapies. Here, we describe the generation and characteristics of a panel of human, high-affinity anti-NKG2D IgG1 monoclonal antibodies (mAbs) derived by phage display. The lead molecule mAb E4 bound with an affinity (KD) of 2.7 ± 1.4 × 10−11 M to soluble and membrane-bound human NKG2D, and cross-reacted with NKG2D from cynomolgus macaque, indicating potential suitability for studies in a relevant primate model. MAb E4 potently antagonized the cytolytic activity of NKL cells against BaF/3-MICA cells expressing NKG2D ligand, and blocked the NKG2D ligand-induced secretion of TNFα, IFNγ and GM-CSF, as well as surface expression of CRTAM by NK cells cultured on immobilized MICA or ULBP-1 ligands. The antibody did not show a detectable loss of binding to NKG2D after seven days in human serum at 37°C, and resisted thermal inactivation up to 70°C. Based on these results, anti-human NKG2D mAb E4 provides an ideal candidate for development of a novel therapeutic agent antagonizing a key receptor of NK and cytotoxic T cells with implications in autoimmune diseases. PMID:20061825

Biofunctionalization of silica-coated magnetic particles mediated by a peptide

NASA Astrophysics Data System (ADS)

Care, Andrew; Chi, Fei; Bergquist, Peter L.; Sunna, Anwar

2014-08-01

A linker peptide sequence with affinity to silica-containing materials was fused to Streptococcus protein G', an antibody-binding protein. This recombinant fusion protein, linker-protein G (LPG) was produced in E. coli and exhibited strong affinity to silica-coated magnetic particles and was able to bind to them at different pHs, indicating a true pH-independent binding. LPG was used as an anchorage point for the oriented immobilization of antibodies onto the surface of the particles. These particle-bound "LPG-Antibody complexes" mediated the binding and recovery of different cell types (e.g., human stem cells, Legionella, Cryptosporidium and Giardia), enabling their rapid and simple visualization and identification. This strategy was used also for the efficient capture of Cryptosporidium oocysts from water samples. These results demonstrate that LPG can mediate the direct biofunctionalization of silica-coated magnetic particles without the need for complex surface chemical modification.

Binding of a neutralizing antibody to dengue virus alters the arrangement of surface glycoproteins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lok, Shee-Mei; Kostyuchenko, Victor; Nybakken, Grant E.

The monoclonal antibody 1A1D-2 has been shown to strongly neutralize dengue virus serotypes 1, 2 and 3, primarily by inhibiting attachment to host cells. A crystal structure of its antigen binding fragment (Fab) complexed with domain III of the viral envelope glycoprotein, E, showed that the epitope would be partially occluded in the known structure of the mature dengue virus. Nevertheless, antibody could bind to the virus at 37 degrees C, suggesting that the virus is in dynamic motion making hidden epitopes briefly available. A cryo-electron microscope image reconstruction of the virus:Fab complex showed large changes in the organization ofmore » the E protein that exposed the epitopes on two of the three E molecules in each of the 60 icosahedral asymmetric units of the virus. The changes in the structure of the viral surface are presumably responsible for inhibiting attachment to cells.« less

Energy of adhesion of human T cells to adsorption layers of monoclonal antibodies measured by a film trapping technique.

PubMed Central

Ivanov, I B; Hadjiiski, A; Denkov, N D; Gurkov, T D; Kralchevsky, P A; Koyasu, S

1998-01-01

A novel method for studying the interaction of biological cells with interfaces (e.g., adsorption monolayers of antibodies) is developed. The method is called the film trapping technique because the cell is trapped within an aqueous film of equilibrium thickness smaller than the cell diameter. A liquid film of uneven thickness is formed around the trapped cell. When observed in reflected monochromatic light, this film exhibits an interference pattern of concentric bright and dark fringes. From the radii of the fringes one can restore the shape of interfaces and the cell. Furthermore, one can calculate the adhesive energy between the cell membrane and the aqueous film surface (which is covered by a layer of adsorbed proteins and/or specific ligands), as well as the disjoining pressure, representing the force of interaction per unit area of the latter film. The method is applied to two human T cell lines: Jurkat and its T cell receptor negative (TCR-) derivative. The interaction of these cells with monolayers of three different monoclonal antibodies adsorbed at a water-air interface is studied. The results show that the adhesive energy is considerable (above 0.5 mJ/m2) when the adsorption monolayer contains antibodies acting as specific ligands for the receptors expressed on the cell surface. In contrast, the adhesive energy is close to zero in the absence of such a specific ligand-receptor interaction. In principle, the method can be applied to the study of the interaction of a variety of biological cells (B cells, natural killer cells, red blood cells, etc.) with adsorption monolayers of various biologically active molecules. In particular, film trapping provides a tool for the gentle micromanipulation of cells and for monitoring of processes (say the activation of a T lymphocyte) occurring at the single-cell level. PMID:9649417

Regulation of T-lymphocyte motility, adhesion and de-adhesion by a cell surface mechanism directed by low density lipoprotein receptor-related protein 1 and endogenous thrombospondin-1.

PubMed

Talme, Toomas; Bergdahl, Eva; Sundqvist, Karl-Gösta

2014-06-01

T lymphocytes are highly motile and constantly reposition themselves between a free-floating vascular state, transient adhesion and migration in tissues. The regulation behind this unique dynamic behaviour remains unclear. Here we show that T cells have a cell surface mechanism for integrated regulation of motility and adhesion and that integrin ligands and CXCL12/SDF-1 influence motility and adhesion through this mechanism. Targeting cell surface-expressed low-density lipoprotein receptor-related protein 1 (LRP1) with an antibody, or blocking transport of LRP1 to the cell surface, perturbed the cell surface distribution of endogenous thrombospondin-1 (TSP-1) while inhibiting motility and potentiating cytoplasmic spreading on intercellular adhesion molecule 1 (ICAM-1) and fibronectin. Integrin ligands and CXCL12 stimulated motility and enhanced cell surface expression of LRP1, intact TSP-1 and a 130,000 MW TSP-1 fragment while preventing formation of a de-adhesion-coupled 110 000 MW TSP-1 fragment. The appearance of the 130 000 MW TSP-1 fragment was inhibited by the antibody that targeted LRP1 expression, inhibited motility and enhanced spreading. The TSP-1 binding site in the LRP1-associated protein, calreticulin, stimulated adhesion to ICAM-1 through intact TSP-1 and CD47. Shear flow enhanced cell surface expression of intact TSP-1. Hence, chemokines and integrin ligands up-regulate a dominant motogenic pathway through LRP1 and TSP-1 cleavage and activate an associated adhesion pathway through the LRP1-calreticulin complex, intact TSP-1 and CD47. This regulation of T-cell motility and adhesion makes pro-adhesive stimuli favour motile responses, which may explain why T cells prioritize movement before permanent adhesion.

Higher cytotoxicity of divalent antibody-toxins than monovalent antibody-toxins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Won, JaeSeon; Nam, PilWon; Lee, YongChan

2009-04-24

Recombinant antibody-toxins are constructed via the fusion of a 'carcinoma-specific' antibody fragment to a toxin. Due to the high affinity and high selectivity of the antibody fragments, antibody-toxins can bind to surface antigens on cancer cells and kill them without harming normal cells [L.H. Pai, J.K. Batra, D.J. FitzGerald, M.C. Willingham, I. Pastan, Anti-tumor activities of immunotoxins made of monoclonal antibody B3 and various forms of Pseudomonas exotoxin, Proc. Natl. Acad. Sci. USA 88 (1991) 3358-3362]. In this study, we constructed the antibody-toxin, Fab-SWn-PE38, with SWn (n = 3, 6, 9) sequences containing n-time repeated (G{sub 4}S) between the Fabmore » fragment and PE38 (38 kDa truncated form of Pseudomonas exotoxin A). The SWn sequence also harbored one cysteine residue that could form a disulfide bridge between two Fab-SWn-PE38 monomers. We assessed the cytotoxicity of the monovalent (Fab-SWn-PE38), and divalent ([Fab-SWn-PE38]{sub 2}) antibody-toxins. The cytotoxicity of the dimer against the CRL1739 cell line was approximately 18.8-fold higher than that of the monomer on the ng/ml scale, which was approximately 37.6-fold higher on the pM scale. These results strongly indicate that divalency provides higher cytotoxicity for an antibody-toxin.« less

Observations on the antibody-dependent cytotoxic cell by scanning electron microscopy.

PubMed Central

Inglis, J R; Penhale, W J; Farmer, A; Irvine, W J; Williams, A E

1975-01-01

The cytotoxic effect of human peripheral blood leucocytes on antibody-coated sheep erythrocyte monolayers has been investigated using scanning electron microscopy. Only a small proportion of leucocytes were found to adhere to the monolayers. A progressive destruction was observed beginning as small plaque-like areas of erythrocyte clearing which later became confluent. Three distinct cell types were found to be associated with the areas of lysis. No destruction was observed in control monolayers incubated for a similar period in the absence of either antibody of leucocytes. Surface changes in the erthrocytes adjacent to the leucocytes suggest that mechanical factors may be involved in erythrocyte lysis in this system. It is concluded that more than one leucocyte type may damage antibody-coated erythrocytes, possibly by a mechanism involving attachment to and mechanical disruption of the red cell membrane. Images FIG. 5 FIG. 2 FIG. 3 FIG. 1 FIG. 2 FIG. 4 PMID:1191386

Protection of Mice from Fatal Measles Encephalitis by Vaccination with Vaccinia Virus Recombinants Encoding Either the Hemagglutinin or the Fusion Protein

NASA Astrophysics Data System (ADS)

Drillien, Robert; Spehner, Daniele; Kirn, Andre; Giraudon, Pascale; Buckland, Robin; Wild, Fabian; Lecocq, Jean-Pierre

1988-02-01

Vaccinia virus recombinants encoding the hemagglutinin or fusion protein of measles virus have been constructed. Infection of cell cultures with the recombinants led to the synthesis of authentic measles proteins as judged by their electrophoretic mobility, recognition by antibodies, glycosylation, proteolytic cleavage, and presentation on the cell surface. Mice vaccinated with a single dose of the recombinant encoding the hemagglutinin protein developed antibodies capable of both inhibiting hemagglutination activity and neutralizing measles virus, whereas animals vaccinated with the recombinant encoding the fusion protein developed measles neutralizing antibodies. Mice vaccinated with either of the recombinants resisted a normally lethal intracerebral inoculation of a cell-associated measles virus subacute sclerosing panencephalitis strain.

Modulation of sickle cell crisis by naturally occurring band 3 specific antibodies -- a malaria link.

PubMed

Kennedy, James Randall

2002-05-01

This paper's focus is prevention of sickle cell adhesion resulting from the erythrocyte's prematurely denatured hemoglobin. This denatured hemoglobin causes a molecule called band 3 to cluster on the erythrocyte's surface and adhere to the CD36 molecule located on the microvascular endothelium. Natural antibodies recognize these clusters on senescent erythrocytes and prevent their endothelial adhesion and target them for reticuloendothelial elimination. Band 3 is also displayed on the erythrocytes of individuals with falciparum malaria and the vaso-occlusive pathology in these patients is prevented in individuals with sickle trait. The hypothesis is that prematurely denatured sickle hemoglobin results in an up regulation of natural antibodies which control erythrocyte adhesion in both malaria and sickle cell disease.

Hematopoietic organs of Manduca sexta and hemocyte lineages.

PubMed

Nardi, James B; Pilas, Barbara; Ujhelyi, Elizabeth; Garsha, Karl; Kanost, Michael R

2003-10-01

Cells of the moth immune system are derived from organs that loosely envelop the four wing imaginal discs. The immune response in these insects is believed to depend on the activities of two main classes of hemocytes: plasmatocytes and granular cells. The fates of cells that arise from these hematopoietic organs have been followed by immunolabeling with plasmatocyte-specific and granular-cell-specific antibodies. Cells within each hematopoietic organ differ in their coherence and in their expression of two plasmatocyte-specific surface proteins, integrin and neuroglian. Within an organ there is no overlap in the expression of these two surface proteins; neuroglian is found on the surfaces of the coherent cells while integrin is expressed on cells that are losing coherence, rounding up, and dispersing. A granular-cell-specific marker for the protein lacunin labels the basal lamina that delimits each organ but only a small number of granular cells that lie on or near the periphery of the hematopoietic organ. When organs are cultured in the absence of hemolymph, all cells derived from hematopoietic organs turn out to immunolabel with the plasmatocyte-specific antibody MS13. The circulating plasmatocytes derived from hematopoietic organs have higher ploidy levels than the granular cells and represent a separate lineage of hemocytes.

Developmental localization and the role of hydroxyproline rich glycoproteins during somatic embryogenesis of banana (Musa spp. AAA)

PubMed Central

2011-01-01

Background Hydroxyproline rich glycoproteins (HRGPs) are implicated to have a role in many aspects of plant growth and development but there is limited knowledge about their localization and function during somatic embryogenesis of higher plants. In this study, the localization and function of hydroxyproline rich glycoproteins in embryogenic cells (ECs) and somatic embryos of banana were investigated by using immunobloting and immunocytochemistry with monoclonal JIM11 and JIM20 antibodies as well as by treatment with 3,4-dehydro-L-proline (3,4-DHP, an inhibitor of extensin biosynthesis), and by immunomodulation with the JIM11 antibody. Results Immunofluorescence labelling of JIM11 and JIM20 hydroxyproline rich glycoprotein epitopes was relatively weak in non-embryogenic cells (NECs), mainly on the edge of small cell aggregates. On the other hand, hydroxyproline rich glycoprotein epitopes were found to be enriched in early embryogenic cells as well as in various developmental stages of somatic embryos. Embryogenic cells (ECs), proembryos and globular embryos showed strong labelling of hydroxyproline rich glycoprotein epitopes, especially in their cell walls and outer surface layer, so-called extracellular matrix (ECM). This hydroxyproline rich glycoprotein signal at embryo surfaces decreased and/or fully disappeared during later developmental stages (e.g. pear-shaped and cotyledonary stages) of embryos. In these later developmental embryogenic stages, however, new prominent hydroxyproline rich glycoprotein labelling appeared in tri-cellular junctions among parenchymatic cells inside these embryos. Overall immunofluorescence labelling of late stage embryos with JIM20 antibody was weaker than that of JIM11. Western blot analysis supported the above immunolocalization data. The treatment with 3,4-DHP inhibited the development of embryogenic cells and decreased the rate of embryo germination. Embryo-like structures, which developed after 3,4-DHP treatment showed aberrant non-compact epidermis with discontinuous ECM at the outer surface as well as much less immunolabelling with the JIM11 antibody. This treatment also decreased the plant regeneration capacity in embryogenic banana cultures. Finally, immunomodulation of surface hydroxyproline rich glycoproteins by co-culture of embryos with the JIM11 antibody resulted in a much lower germination capacity of these embryos. Conclusions These results suggest that hydroxyproline rich glycoproteins play an important developmental role, especially in the process of regeneration and germination of embryos during plant regeneration via somatic embryogenesis. Proper content and localization of hydroxyproline rich glycoproteins seem to be essential for the formation and regeneration of banana somatic embryos. PMID:21349190

Differential recognition of P. falciparum VAR2CSA domains by naturally acquired antibodies in pregnant women from a malaria endemic area.

PubMed

Brolin, Kim J M; Persson, Kristina E M; Wahlgren, Mats; Rogerson, Stephen J; Chen, Qijun

2010-02-16

Plasmodium falciparum infected red blood cells (iRBC) express variant surface antigens (VSA) of which VAR2CSA is involved in placental sequestration and causes pregnancy-associated malaria (PAM). Primigravidae are most susceptible to PAM whereas antibodies associated with protection are often present at higher levels in multigravid women. However, HIV co-infection with malaria has been shown to alter this parity-dependent acquisition of immunity, with more severe symptoms as well as more malaria episodes in HIV positive women versus HIV negative women of a similar parity. Using VAR2CSA DBL-domains expressed on the surface of CHO-745 cells we quantified levels of DBL-domain specific IgG in sera from pregnant Malawian women by flow cytometry. Dissociations constants of DBL5epsilon specific antibodies were determined using a surface plasmon resonance technique, as an indication of antibody affinities. VAR2CSA DBL5epsilon was recognized in a gender and parity-dependent manner with anti-DBL5epsilon IgG correlating significantly with IgG levels to VSA-PAM on the iRBC surface. HIV positive women had lower levels of anti-DBL5epsilon IgG than HIV negative women of similar parity. In primigravidae, antibodies in HIV positive women also showed significantly lower affinity to VAR2CSA DBL5epsilon. Pregnant women from a malaria-endemic area had increased levels of anti-DBL5epsilon IgG by parity, indicating this domain of VAR2CSA to be a promising vaccine candidate against PAM. However, it is important to consider co-infection with HIV, as this seems to change the properties of antibody response against malaria. Understanding the characteristics of antibody response against VAR2CSA is undoubtedly imperative in order to design a functional and efficient vaccine against PAM.

IMMUNOREACTIONS INVOLVING PLATELETS

PubMed Central

Shulman, N. Raphael

1958-01-01

A steric and kinetic model for the sequence and mechanism of reactions leading to formation of a complex from an antibody, a haptene (quinidine), and a cell membrane (platelets), and to fixation of complement by the complex was deduced from the effects of varying the initial concentration of each component of the complex on the amount of complement fixed, from kinetic aspects of the sequential reactions, and from other chemical and physical properties of the various components involved. Theoretical results calculated using equations based on the model, which were derived by Dr. Terrell L. Hill, were similar in all respects to experimental results. Results of this study were consistent with the possibilities that the protein moiety of a haptenic antigen involved in development of an antibody which attaches to a cell is not necessarily a component of the cell, and that the cell reacts with the antibody by virtue of having a surface favorable for non-specific adsorption of certain haptene-antibody complexes. PMID:13525578

Selective Blockade of Human Natural Killer Cells by a Monoclonal Antibody

NASA Astrophysics Data System (ADS)

Newman, Walter

1982-06-01

A murine monoclonal antibody, 13.1, which blocks human natural killer (NK) cell-mediated lysis, has been developed. Hybridoma 13.1 was derived by fusion of NS-1 cells with spleen cells from mice immunized with an enriched population of NK cells. Supernatants of growing hybridomas were screened for their ability to block NK cell-mediated lysis of K562 targets. Antibody 13.1 is an IgG1 with a single light chain type and it does not fix complement. The 13.1 antigen is expressed on all peripheral blood mononuclear cells, with an antigen density approximately 1/30th that of HLA antigen heavy chain. Pretreatment and washing experiments revealed that inhibition of cytotoxicity occurred at the effector cell level only. Significant blocking was achieved with nanogram quantities of antibody and was not due to toxic effects on NK cells. Likewise, controls with other antibodies of the same subclass demonstrated that blocking was not a consequence of mere binding to NK cells. When a panel of 17 NK cell-susceptible targets was tested, the lysis of only 5 of these was blocked, namely K562, HL-60, KG-1, Daudi, and HEL, a human erythroleukemic cell line. The lysis of 12 human B cell and T cell line targets was not inhibited. In addition to the demonstration that the 13.1 antigen is a crucial cell surface structure involved in NK lysis, a heterogeneity of target cell recognition has been revealed that argues for the proposition that individual NK cells have multiple recognitive capabilities.

CELL SEPARATION ON ANTIGEN-COATED COLUMNS

PubMed Central

Wigzell, Hans; Andersson, Birger

1969-01-01

Glass and plastic bead columns coated with antigenic protein molecules were used as an immunological filter for cell populations containing immune cells of relevant specificity. A selective elimination of these immune cells from the passing cell suspension was regularly noted and it approached, in some experiments, complete abolition of the specific immune reactivity of the filtered cell population. This specific retention of immune cells by antigenic columns could be selectively blocked by the presence of free antigen molecules in the medium during filtration. The results obtained support the concept of a cell-associated antigen-specific receptor being present on the outer surface of immune cells, displaying the same antigen-binding specificity as the potential product of the cell, the humoral antibody. Using the present bead column system, results were obtained indicating that this receptor was an active product of the immune cells and not any passively adsorbed, cytophilic antibody. Antigenic bead columns may very well constitute a tool for the production in vitro of cell populations being specifically deprived of immune reactivity and allow detailed analysis of the characteristics of the cell-associated antibody of immune cells. PMID:5782770

Tuning B cell responses to antigens by cell polarity and membrane trafficking.

PubMed

Del Valle Batalla, Felipe; Lennon-Dumenil, Ana-María; Yuseff, María-Isabel

2018-06-20

The capacity of B lymphocytes to produce specific antibodies, particularly broadly neutralizing antibodies that provide immunity to viral pathogens has positioned them as valuable therapeutic targets for immunomodulation. To become competent as antibody secreting cells, B cells undergo a series of activation steps, which are triggered by the recognition of antigens frequently displayed on the surface of other presenting cells. Such antigens elicit the formation of an immune synapse (IS), where local cytoskeleton rearrangements coupled to mechanical forces and membrane trafficking orchestrate the extraction and processing of antigens in B cells. In this review, we discuss the molecular mechanisms that regulate polarized membrane trafficking and mechanical properties of the immune synapse, as well as the potential extracellular cues from the environment, which may impact the ability of B cells to sense and acquire antigens at the immune synapse. An integrated view of the diverse cellular mechanisms that shape the immune synapse will provide a better understanding on how B cells are efficiently activated. Copyright © 2018 Elsevier Ltd. All rights reserved.

Human recombinant Fab fragment from combinatorial libraries of a B-cell lymphoma patient recognizes core protein of chondroitin sulphate proteoglycan 4.

PubMed

Egami, Yoko; Narushima, Yuta; Ohshima, Motohiro; Yoshida, Akira; Yoneta, Naruki; Masaki, Yasufumi; Itoh, Kunihiko

2018-01-01

CD antigens are well known as therapeutic targets of B-cell lymphoma. To isolate therapeutic antibodies that recognize novel targets other than CD antigens, we constructed a phage display combinatorial antibody Fab library from bone marrow lymphocytes of B-cell lymphoma patient. To eliminate antibodies reactive with known B-cell lymphoma antigen, non-hematopoietic and patient's sera reactive HeLaS3 cells was selected as a target of whole cell panning. Five rounds of panning against live HeLaS3 cells retrieved single Fab clone, termed AHSA (Antibody to HeLa Surface Antigen). Using phage display random peptide library, LSYLEP was identified as an epitope sequence of AHSA. LC-MS/MS analysis of AHSA-precipitated HeLaS3 cell lysates detected several fragments corresponding to the sequence of chondroitin sulphate proteoglycan 4 (CSPG4) core protein. Since LSYLEP sequence was at the position of 313-318 of CSPG4, we considered that CSPG4 was AHSA-associated antigen. Double staining of CSPG4-postive MDA-MB-435S cells with AHSA and anti-CSPG4 rabbit antibody showed identical staining position, and reduced AHSA reactivity was observed in CSPG4-siRNA treated MDA-MB-435S cells. In conclusion, we retrieved a human Fab from antibody library of B-cell lymphoma patient, and identified CSPG4 as a recognizing antigen. AHSA may have potential benefits for development of CSPG4-targeting theranostics for B-cell lymphoma. © The Authors 2017. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

Receptor for advanced glycation end products (RAGE) functions as receptor for specific sulfated glycosaminoglycans, and anti-RAGE antibody or sulfated glycosaminoglycans delivered in vivo inhibit pulmonary metastasis of tumor cells.

PubMed

Mizumoto, Shuji; Takahashi, Jun; Sugahara, Kazuyuki

2012-06-01

Altered expression of chondroitin sulfate (CS) and heparan sulfate (HS) at the surfaces of tumor cells plays a key role in malignant transformation and tumor metastasis. Previously we demonstrated that a Lewis lung carcinoma (LLC)-derived tumor cell line with high metastatic potential had a higher proportion of E-disaccharide units, GlcUA-GalNAc(4,6-O-disulfate), in CS chains than low metastatic LLC cells and that such CS chains are involved in the metastatic process. The metastasis was markedly inhibited by the pre-administration of CS-E from squid cartilage rich in E units or by preincubation with a phage display antibody specific for CS-E. However, the molecular mechanism of the inhibition remains to be investigated. In this study the receptor molecule for CS chains containing E-disaccharides expressed on LLC cells was revealed to be receptor for advanced glycation end products (RAGE), which is a member of the immunoglobulin superfamily predominantly expressed in the lung. Interestingly, RAGE bound strongly to not only E-disaccharide, but also HS-expressing LLC cells. Furthermore, the colonization of the lungs by LLC cells was effectively inhibited by the blocking of CS or HS chains at the tumor cell surface with an anti-RAGE antibody through intravenous injections in a dose-dependent manner. These results provide the clear evidence that RAGE is at least one of the critical receptors for CS and HS chains expressed at the tumor cell surface and involved in experimental lung metastasis and that CS/HS and RAGE are potential molecular targets in the treatment of pulmonary metastasis.

Antibodies against CD20 or B-Cell Receptor Induce Similar Transcription Patterns in Human Lymphoma Cell Lines

PubMed Central

Franke, Andreas; Niederfellner, Gerhard J.; Klein, Christian; Burtscher, Helmut

2011-01-01

Background CD20 is a cell surface protein exclusively expressed on B cells. It is a clinically validated target for Non-Hodgkin's lymphomas (NHL) and autoimmune diseases. The B cell receptor (BCR) plays an important role for development and proliferation of pre-B and B cells. Physical interaction of CD20 with BCR and components of the BCR signaling cascade has been reported but the consequences are not fully understood. Methodology In this study we employed antibodies against CD20 and against the BCR to trigger the respective signaling. These antibodies induced very similar expression patterns of up- and down-regulated genes in NHL cell lines indicating that CD20 may play a role in BCR signaling and vice versa. Two of the genes that were rapidly and transiently induced by both stimuli are CCL3 and CCL4. 4 hours after stimulation the concentration of these chemokines in culture medium reaches a maximum. Spleen tyrosine kinase Syk is a cytoplasmic tyrosine kinase and a key component of BCR signaling. Both siRNA mediated silencing of Syk and inhibition by selective small molecule inhibitors impaired CCL3/CCL4 protein induction after treatment with either anti-CD20 or anti-BCR antibodies. Conclusion Our results suggest that treatment with anti-CD20 antibodies triggers at least partially a BCR activation-like response in NHL cell lines. PMID:21364752

Identification of a novel mechanism of action of bovine IgG antibodies specific for Staphylococcus aureus.

PubMed

Furukawa, Mutsumi; Yoneyama, Hiroshi; Hata, Eiji; Iwano, Hidetomo; Higuchi, Hidetoshi; Ando, Tasuke; Sato, Mika; Hayashi, Tomohito; Kiku, Yoshio; Nagasawa, Yuya; Niimi, Kanae; Usami, Katsuki; Ito, Kumiko; Watanabe, Kouichi; Nochi, Tomonori; Aso, Hisashi

2018-02-26

Staphylococcus aureus is a major pathogen that causes subclinical mastitis associated with huge economic losses to the dairy industry. A few vaccines for bovine mastitis are available, and they are expected to induce the production of S. aureus-specific antibodies that prevent bacterial adherence to host cells or promote opsonization by phagocytes. However, the efficacy of such vaccines are still under debate; therefore, further research focusing on improving the current vaccines by seeking additional mechanisms of action is required to reduce economic losses due to mastitis in the dairy industry. Here, we generated S. aureus-specific bovine IgG antibodies (anti-S. aureus) that directly inhibited bacterial growth in vitro. Inhibition depended on specificity for anti-S. aureus, not the interaction between Protein A and the fragment crystallizable region of the IgG antibodies or bacterial agglutination. An in vitro culture study using S. aureus strain JE2 and its deletion mutant JE2ΔSrtA, which lacks the gene encoding sortase A, revealed that the effect of anti-S. aureus was sortase-A-independent. Sortase A is involved in the synthesis of cell-wall-associated proteins. Thus, other surface molecules, such as membrane proteins, cell surface polysaccharides, or both, may trigger the inhibition of bacterial growth by anti-S. aureus. Together, our findings contribute insights into developing new strategies to further improve the available mastitis vaccine by designing a novel antigen on the surface of S. aureus to induce inhibitory signals that prevent bacterial growth.

Rebmab200, a humanized monoclonal antibody targeting the sodium phosphate transporter NaPi2b displays strong immune mediated cytotoxicity against cancer: a novel reagent for targeted antibody therapy of cancer.

PubMed

Lopes dos Santos, Mariana; Yeda, Fernanda Perez; Tsuruta, Lilian Rumi; Horta, Bruno Brasil; Pimenta, Alécio A; Degaki, Theri Leica; Soares, Ibere C; Tuma, Maria Carolina; Okamoto, Oswaldo Keith; Alves, Venancio A F; Old, Lloyd J; Ritter, Gerd; Moro, Ana Maria

2013-01-01

NaPi2b, a sodium-dependent phosphate transporter, is highly expressed in ovarian carcinomas and is recognized by the murine monoclonal antibody MX35. The antibody had shown excellent targeting to ovarian cancer in several early phase clinical trials but being murine the antibody's full therapeutic potential could not be explored. To overcome this impediment we developed a humanized antibody version named Rebmab200, expressed in human PER.C6® cells and cloned by limiting dilution. In order to select a clone with high therapeutic potential clones were characterized using a series of physicochemical assays, flow cytometry, real-time surface plasmon resonance, glycosylation analyses, immunohistochemistry, antibody-dependent cell-mediated cytotoxicity, complement-dependent-cytotoxicity assays and quantitative PCR. Comparative analyses of Rebmab200 and MX35 monoclonal antibodies demonstrated that the two antibodies had similar specificity for NaPi2b by flow cytometry with a panel of 30 cell lines and maintained similar kinetic parameters. Robust and high producer cell clones potentially suitable for use in manufacturing were obtained. Rebmab200 antibodies were assessed by immunohistochemistry using a large panel of tissues including human carcinomas of ovarian, lung, kidney and breast origin. An assessment of its binding towards 33 normal human organs was performed as well. Rebmab200 showed selected strong reactivity with the tested tumor types but little or no reactivity with the normal tissues tested confirming its potential for targeted therapeutics strategies. The remarkable cytotoxicity shown by Rebmab200 in OVCAR-3 cells is a significant addition to the traits of stability and productivity displayed by the top clones of Rebmab200. Antibody-dependent cell-mediated toxicity functionality was confirmed in repeated assays using cancer cell lines derived from ovary, kidney and lung as targets. To explore use of this antibody in clinical trials, GMP production of Rebmab200 has been initiated. As the next step of development, Phase I clinical trials are now planned for translation of Rebmab200 into the clinic.

Rebmab200, a Humanized Monoclonal Antibody Targeting the Sodium Phosphate Transporter NaPi2b Displays Strong Immune Mediated Cytotoxicity against Cancer: A Novel Reagent for Targeted Antibody Therapy of Cancer

PubMed Central

dos Santos, Mariana Lopes; Yeda, Fernanda Perez; Tsuruta, Lilian Rumi; Horta, Bruno Brasil; Pimenta, Alécio A.; Degaki, Theri Leica; Soares, Ibere C.; Tuma, Maria Carolina; Okamoto, Oswaldo Keith; Alves, Venancio A. F.; Ritter, Gerd; Moro, Ana Maria

2013-01-01

NaPi2b, a sodium-dependent phosphate transporter, is highly expressed in ovarian carcinomas and is recognized by the murine monoclonal antibody MX35. The antibody had shown excellent targeting to ovarian cancer in several early phase clinical trials but being murine the antibody's full therapeutic potential could not be explored. To overcome this impediment we developed a humanized antibody version named Rebmab200, expressed in human PER.C6® cells and cloned by limiting dilution. In order to select a clone with high therapeutic potential clones were characterized using a series of physicochemical assays, flow cytometry, real-time surface plasmon resonance, glycosylation analyses, immunohistochemistry, antibody-dependent cell-mediated cytotoxicity, complement-dependent-cytotoxicity assays and quantitative PCR. Comparative analyses of Rebmab200 and MX35 monoclonal antibodies demonstrated that the two antibodies had similar specificity for NaPi2b by flow cytometry with a panel of 30 cell lines and maintained similar kinetic parameters. Robust and high producer cell clones potentially suitable for use in manufacturing were obtained. Rebmab200 antibodies were assessed by immunohistochemistry using a large panel of tissues including human carcinomas of ovarian, lung, kidney and breast origin. An assessment of its binding towards 33 normal human organs was performed as well. Rebmab200 showed selected strong reactivity with the tested tumor types but little or no reactivity with the normal tissues tested confirming its potential for targeted therapeutics strategies. The remarkable cytotoxicity shown by Rebmab200 in OVCAR-3 cells is a significant addition to the traits of stability and productivity displayed by the top clones of Rebmab200. Antibody-dependent cell-mediated toxicity functionality was confirmed in repeated assays using cancer cell lines derived from ovary, kidney and lung as targets. To explore use of this antibody in clinical trials, GMP production of Rebmab200 has been initiated. As the next step of development, Phase I clinical trials are now planned for translation of Rebmab200 into the clinic. PMID:23936189

Toward low-cost affinity reagents: lyophilized yeast-scFv probes specific for pathogen antigens.

PubMed

Gray, Sean A; Weigel, Kris M; Ali, Ibne K M; Lakey, Annie A; Capalungan, Jeremy; Domingo, Gonzalo J; Cangelosi, Gerard A

2012-01-01

The generation of affinity reagents, usually monoclonal antibodies, remains a critical bottleneck in biomedical research and diagnostic test development. Recombinant antibody-like proteins such as scFv have yet to replace traditional monoclonal antibodies in antigen detection applications, in large part because of poor performance of scFv in solution. To address this limitation, we have developed assays that use whole yeast cells expressing scFv on their surfaces (yeast-scFv) in place of soluble purified scFv or traditional monoclonal antibodies. In this study, a nonimmune library of human scFv displayed on the surfaces of yeast cells was screened for clones that bind to recombinant cyst proteins of Entamoeba histolytica, an enteric pathogen of humans. Selected yeast-scFv clones were stabilized by lyophilization and used in detection assay formats in which the yeast-scFv served as solid support-bound monoclonal antibodies. Specific binding of antigen to the yeast-scFv was detected by staining with rabbit polyclonal antibodies. In flow cytometry-based assays, lyophilized yeast-scFv reagents retained full binding activity and specificity for their cognate antigens after 4 weeks of storage at room temperature in the absence of desiccants or stabilizers. Because flow cytometry is not available to all potential assay users, an immunofluorescence assay was also developed that detects antigen with similar sensitivity and specificity. Antigen-specific whole-cell yeast-scFv reagents can be selected from nonimmune libraries in 2-3 weeks, produced in vast quantities, and packaged in lyophilized form for extended shelf life. Lyophilized yeast-scFv show promise as low cost, renewable alternatives to monoclonal antibodies for diagnosis and research.

Presence of MUC4 in human milk and at the luminal surfaces of blood vessels.

PubMed

Zhang, Jin; Perez, Aymee; Yasin, Mohammad; Soto, Pedro; Rong, Min; Theodoropoulos, George; Carothers Carraway, Coralie A; Carraway, Kermit L

2005-07-01

MUC4 is a heterodimeric membrane mucin, composed of a mucin subunit ASGP-1 (MUC4alpha) and a transmembrane subunit ASGP-2 (MUC4beta), which has been implicated in the protection of epithelial cell surfaces. Surprisingly, development and characterization of a new monoclonal antibody (mAb), called 1G8, against ASGP-2 demonstrated by immunohistochemistry the presence of MUC4 at the luminal surfaces of blood vessels of both normal tissues and tumors. Muc4 was detected with 1G8 and other Muc4 antibodies in blood vessels from humans, rats and mice. This expression of MUC4 in endothelial cells was confirmed by immunoblotting with 1G8 in human umbilical vein endothelial cells (HUVECs), human iliac artery endothelial cells (HIAECs), and human microvascular endothelial cells (HMVECs). MUC4 could be observed on HUVECs grown on either plastic or Matrigel. Finally, MUC4 expression in the three types of endothelial cell lines was confirmed by reverse transcription-polymerase chain reaction (RT-PCR). These results provide, to our knowledge, the first demonstration of a member of the MUC gene family and membrane mucin in blood vessels. As a luminal surface component, the MUC4 is situated to contribute to the non-adhesive luminal surface and to act as an intrinsic protection and survival factor. (c) 2004 Wiley-Liss, Inc.

Modular synthesis of N-glycans and arrays for the hetero-ligand binding analysis of HIV antibodies

NASA Astrophysics Data System (ADS)

Shivatare, Sachin S.; Chang, Shih-Huang; Tsai, Tsung-I.; Tseng, Susan Yu; Shivatare, Vidya S.; Lin, Yih-Shyan; Cheng, Yang-Yu; Ren, Chien-Tai; Lee, Chang-Chun David; Pawar, Sujeet; Tsai, Charng-Sheng; Shih, Hao-Wei; Zeng, Yi-Fang; Liang, Chi-Hui; Kwong, Peter D.; Burton, Dennis R.; Wu, Chung-Yi; Wong, Chi-Huey

2016-04-01

A new class of broadly neutralizing antibodies (bNAbs) from HIV donors has been reported to target the glycans on gp120—a glycoprotein found on the surface of the virus envelope—thus renewing hope of developing carbohydrate-based HIV vaccines. However, the version of gp120 used in previous studies was not from human T cells and so the glycosylation pattern could be somewhat different to that found in the native system. Moreover, some antibodies recognized two different glycans simultaneously and this cannot be detected with the commonly used glycan microarrays on glass slides. Here, we have developed a glycan microarray on an aluminium-oxide-coated glass slide containing a diverse set of glycans, including homo- and mixed N-glycans (high-mannose, hybrid and complex types) that were prepared by modular chemo-enzymatic methods to detect the presence of hetero-glycan binding behaviours. This new approach allows rapid screening and identification of optimal glycans recognized by neutralizing antibodies, and could speed up the development of HIV-1 vaccines targeting cell surface glycans.

Heterogeneity of clonogenic cells in acute myeloblastic leukemia.

PubMed Central

Sabbath, K D; Ball, E D; Larcom, P; Davis, R B; Griffin, J D

1985-01-01

The expression of differentiation-associated surface antigens by the clonogenic leukemic cells from 20 patients with acute myeloblastic leukemia (AML) was studied with a panel of seven cytotoxic monoclonal antibodies (anti-Ia, -MY9, -PM-81, -AML-2-23, -Mol, -Mo2, and -MY3). The surface antigen phenotypes of the clonogenic cells were compared with the phenotypes of the whole leukemic cell population, and with the phenotypes of normal hematopoietic progenitor cells. In each case the clonogenic leukemic cells were found within a distinct subpopulation that was less "differentiated" than the total cell population. Clonogenic leukemic cells from different patients could be divided into three phenotype groups. In the first group (7 of 20 cases), the clonogenic cells expressed surface antigens characteristic of the normal multipotent colony-forming cell (Ia, MY9). These cases tended to have "undifferentiated" (FAB M1) morphology, and the total cell population generally lacked expression of "late" monocyte antigens such as MY3 and Mo2. A second group (seven cases) of clonogenic cells expressed surface antigens characteristic of an "early" (day 14) colony-forming unit granulocyte-monocyte (CFU-GM), and a third group (six cases) was characteristic of a "late" (day 7) CFU-GM. The cases in these latter two groups tended to have myelomonocytic (FAB M4) morphology and to express monocyte surface antigens. These results suggest that the clonogenic cells are a distinct subpopulation in all cases of AML, and may be derived from normal hematopoietic progenitor cells at multiple points in the differentiation pathway. The results further support the possibility that selected monoclonal antibodies have the potential to purge leukemic clonogenic cells from bone marrow in some AML patients without eliminating critical normal progenitor cells. PMID:3855866

Heterogeneity of clonogenic cells in acute myeloblastic leukemia.

PubMed

Sabbath, K D; Ball, E D; Larcom, P; Davis, R B; Griffin, J D

1985-02-01

The expression of differentiation-associated surface antigens by the clonogenic leukemic cells from 20 patients with acute myeloblastic leukemia (AML) was studied with a panel of seven cytotoxic monoclonal antibodies (anti-Ia, -MY9, -PM-81, -AML-2-23, -Mol, -Mo2, and -MY3). The surface antigen phenotypes of the clonogenic cells were compared with the phenotypes of the whole leukemic cell population, and with the phenotypes of normal hematopoietic progenitor cells. In each case the clonogenic leukemic cells were found within a distinct subpopulation that was less "differentiated" than the total cell population. Clonogenic leukemic cells from different patients could be divided into three phenotype groups. In the first group (7 of 20 cases), the clonogenic cells expressed surface antigens characteristic of the normal multipotent colony-forming cell (Ia, MY9). These cases tended to have "undifferentiated" (FAB M1) morphology, and the total cell population generally lacked expression of "late" monocyte antigens such as MY3 and Mo2. A second group (seven cases) of clonogenic cells expressed surface antigens characteristic of an "early" (day 14) colony-forming unit granulocyte-monocyte (CFU-GM), and a third group (six cases) was characteristic of a "late" (day 7) CFU-GM. The cases in these latter two groups tended to have myelomonocytic (FAB M4) morphology and to express monocyte surface antigens. These results suggest that the clonogenic cells are a distinct subpopulation in all cases of AML, and may be derived from normal hematopoietic progenitor cells at multiple points in the differentiation pathway. The results further support the possibility that selected monoclonal antibodies have the potential to purge leukemic clonogenic cells from bone marrow in some AML patients without eliminating critical normal progenitor cells.

Preparation of miniantibodies to Azospirillum brasilense Sp245 surface antigens and their use for bacterial detection.

PubMed

Dykman, Lev A; Staroverov, Sergei A; Guliy, Olga I; Ignatov, Oleg V; Fomin, Alexander S; Vidyasheva, Irina V; Karavaeva, Olga A; Bunin, Viktor D; Burygin, Gennady L

2012-01-01

This article reports the first preparation of miniantibodies to Azospirillum brasilense Sp245 surface antigens by using a combinatorial phage library of sheep antibodies. The prepared phage antibodies were used for the first time for lipopolysaccharide and flagellin detection by dot assay, electro-optical analysis of cell suspensions, and transmission electron microscopy. Interaction of A. brasilense Sp245 with antilipopolysaccharide and antiflagellin phage-displayed miniantibodies caused the magnitude of the electro-optical signal to change considerably. The electro-optical results were in good agreement with the electron microscopic data. This is the first reported possibility of employing phage-displayed miniantibodies in bacterial detection aided by electro-optical analysis of cell suspensions.

Evaluation of different micro/nanobeads used as amplifiers in QCM immunosensor for more sensitive detection of E. coli O157:H7.

PubMed

Jiang, Xuesong; Wang, Ronghui; Wang, Yun; Su, Xiaoli; Ying, Yibin; Wang, Jianping; Li, Yanbin

2011-11-15

Micro/nanobeads with different materials (magnetic, silica and polymer) and different sizes (diameters from 30nm to 970nm) were investigated for their use as amplifiers in a quartz crystal microbalance (QCM) immunosensor for more sensitive detection of Escherichia coli O157:H7. The micro/nanobeads were conjugated with anti-E. coli antibodies. E. coli O157:H7 cells were first captured by the first antibody immobilized on the electrode surface, and then micro/nanobeads labeled secondary antibodies attached to the cells, and finally the complexes of antibody-E. coli-antibody modified beads were formed. The results showed that antibody-labeled beads lead to signal amplification in both the change in frequency (ΔF) and the change in resistance (ΔR). Since the penetration depth of the oscillation-induced shear-waves for a ∼8MHz crystal is limited to 200nm, the interpretation of how the signal is amplified by the adsorbed particles was represented in terms of the coupled-oscillator theory. The amplification is not sensed in terms of increase in mass on the sensor surface. Amplification is sensed as a change in bacterial resonance frequency when the spheres adsorb to the bacteria. The change in the values of ΔF caused by different micro/nanobeads (amplifiers) attaching on target bacterial cells is indicative of the ratio between the resonance frequency of the absorbed bacterial-particle complex (ω(s)), and the resonance frequency of the crystal (ω). Copyright © 2011 Elsevier B.V. All rights reserved.

Tumours can act as adjuvants for humoral immunity

PubMed Central

Brown, D M; Fisher, T L; Wei, C; Frelinger, J G; Lord, E M

2001-01-01

Tumour cells transfected with cDNAs encoding non-self proteins were used to investigate the ability of the immune system to respond to immunogenic antigens expressed by tumours. Secreted, intracellular and surface proteins were used as model antigens, as these reflect the potential forms of tumour antigens. Syngeneic BALB/c mice injected with viable line 1 lung carcinoma or EMT6 mammary tumour cells secreting ovalbumin (OVA) or prostate-specific antigen (PSA) produced very high immunoglobulin G (IgG) antibody titres, equivalent to those of mice injected with protein in Freund's complete adjuvant (FCA). Secretion of the antigens was not necessary as tumour cells expressing a cell-surface antigen (HER-2/Neu) or an intracellular antigen – green fluorescence protein (GFP) – also generated high-titre antigen-specific IgG antibodies. In interleukin-4 (IL-4)-deficient mice, both IgG1 and IgG2a were produced in response to OVA administered in FCA, whereas in response to tumour-produced antigen, the antibodies switched from predominantly IgG1 to IgG2a, indicating that the mechanisms responsible for antibody induction differed between these forms of immunization. In contrast to the line 1 and EMT6 tumours, which are of BALB/c origin, OVA- or PSA-producing B16 melanoma cells, which are of C57BL/6 origin, failed to elicit antibody production. This was not the result of strain differences, as a similar finding was observed when the tumours were grown in (BALB/c × C57BL/6)F1 mice, but appeared to be caused by intrinsic differences in the tumours. Furthermore, co-injection of both B16/OVA and line 1 tumours resulted in production of anti-OVA antibody, indicating that B16 tumours were not immunosuppressive, but instead line 1 tumours appear to exert an adjuvant effect. PMID:11328383

Electron microscopy localization and characterization of functionalized composite organic-inorganic SERS nanoparticles on leukemia cells.

PubMed

Koh, Ai Leen; Shachaf, Catherine M; Elchuri, Sailaja; Nolan, Garry P; Sinclair, Robert

2008-12-01

We demonstrate the use of electron microscopy as a powerful characterization tool to identify and locate antibody-conjugated composite organic-inorganic nanoparticle (COINs) surface enhanced Raman scattering (SERS) nanoparticles on cells. U937 leukemia cells labeled with antibody CD54-conjugated COINs were characterized in their native, hydrated state using wet scanning electron microscopy (SEM) and in their dehydrated state using high-resolution SEM. In both cases, the backscattered electron (BSE) detector was used to detect and identify the silver constituents in COINs due to its high sensitivity to atomic number variations within a specimen. The imaging and analytical capabilities in the SEM were further complemented by higher resolution transmission electron microscopy (TEM) images and scanning Auger electron spectroscopy (AES) data to give reliable and high-resolution information about nanoparticles and their binding to cell surface antigens.

Electron Microscopy Localization and Characterization of Functionalized Composite Organic-Inorganic SERS Nanoparticles on Leukemia Cells

PubMed Central

Koh, Ai Leen; Shachaf, Catherine M.; Elchuri, Sailaja; Nolan, Garry P.; Sinclair, Robert

2008-01-01

We demonstrate the use of electron microscopy as a powerful characterization tool to identify and locate antibody-conjugated composite organic-inorganic (COINs) surface enhanced Raman scattering (SERS) nanoparticles on cells. U937 leukemia cells labeled with antibody CD54-conjugated COINs were characterized in their native, hydrated state using wet Scanning Electron Microscopy (SEM) and in their dehydrated state using high-resolution SEM. In both cases, the backscattered electron detector (BSE) was used to detect and identify the silver constituents in COINs due to its high sensitivity to atomic number variations within a specimen. The imaging and analytical capabilities in the SEM were further complemented by higher resolution Transmission Electron Microscope (TEM) images and Scanning Auger Electron Spectroscopy (AES) data to give reliable and high-resolution information about nanoparticles and their binding to cell surface antigens. PMID:18995965

Antibody-mediated targeting of replication-competent retroviral vectors.

PubMed

Tai, Chien-Kuo; Logg, Christopher R; Park, Jinha M; Anderson, W French; Press, Michael F; Kasahara, Noriyuki

2003-05-20

Replication-competent murine leukemia virus (MLV) vectors can be engineered to achieve high efficiency gene transfer to solid tumors in vivo and tumor-restricted replication, however their safety can be further enhanced by redirecting tropism of the virus envelope. We have therefore tested the targeting capability and replicative stability of ecotropic and amphotropic replication-competent retrovirus (RCR) vectors containing two tandem repeats from the immunoglobulin G-binding domain of Staphylococcal protein A inserted into the proline-rich "hinge" region of the envelope, which enables modular use of antibodies of various specificities for vector targeting. The modified envelopes were efficiently expressed and incorporated into virions, were capable of capturing monoclonal anti-HER2 antibodies, and mediated efficient binding of the virus-antibody complex to HER2-positive target cells. While infectivity was markedly reduced by pseudotyping with targeted envelopes alone, coexpression of wild-type envelope rescued efficient cellular entry. Both ecotropic and amphotropic RCR vector/anti-HER2 antibody complexes achieved significant enhancement of transduction on murine target cells overexpressing HER2, which could be competed by preincubation with excess free antibodies. Interestingly, HER2-expressing human breast cancer cells did not show enhancement of transduction despite efficient antibody-mediated cell surface binding, suggesting that target cell-specific parameters markedly affect the efficiency of post-binding entry processes. Serial replication of targeted vectors resulted in selection of Z domain deletion variants, but reduction of the overall size of the vector genome enhanced its stability. Application of antibody-mediated targeting to the initial localization of replication-competent virus vectors to tumor sites will thus require optimized target selection and vector design.

Ebola virus-like particles produced in insect cells exhibit dendritic cell stimulating activity and induce neutralizing antibodies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye Ling; Lin Jianguo; Sun Yuliang

2006-08-01

Recombinant baculoviruses (rBV) expressing Ebola virus VP40 (rBV-VP40) or GP (rBV-GP) proteins were generated. Infection of Sf9 insect cells by rBV-VP40 led to assembly and budding of filamentous particles from the cell surface as shown by electron microscopy. Ebola virus-like particles (VLPs) were produced by coinfection of Sf9 cells with rBV-VP40 and rBV-GP, and incorporation of Ebola GP into VLPs was demonstrated by SDS-PAGE and Western blot analysis. Recombinant baculovirus infection of insect cells yielded high levels of VLPs, which were shown to stimulate cytokine secretion from human dendritic cells similar to VLPs produced in mammalian cells. The immunogenicity ofmore » Ebola VLPs produced in insect cells was evaluated by immunization of mice. Analysis of antibody responses showed that most of the GP-specific antibodies were of the IgG2a subtype, while no significant level of IgG1 subtype antibodies specific for GP was induced, indicating the induction of a Th1-biased immune response. Furthermore, sera from Ebola VLP immunized mice were able to block infection by Ebola GP pseudotyped HIV virus in a single round infection assay, indicating that a neutralizing antibody against the Ebola GP protein was induced. These results show that production of Ebola VLPs in insect cells using recombinant baculoviruses represents a promising approach for vaccine development against Ebola virus infection.« less

Production and characterization of murine monoclonal antibody against synthetic peptide of CD34.

PubMed

Maleki, Leili Aghebati; Majidi, Jafar; Baradaran, Behzad; Abdolalizadeh, Jalal; Akbari, Aliakbar Movassaghpour

2013-01-01

The treatment of hematologic malignancies and immunodeficiency diseases are offered by hematopoietic stem cells (HSCs) as a unique self-renewal and differentiation source which most commonly is selected by CD34 surface marker for HSC. The purpose of this study was to develop and characterize monoclonal antibody against CD34 antigen for detection of hematopoietic stem cells. Balb/c mice were immunized with two synthetic peptides of CD34 and Spleen cells were fused with SP2/0.Fused cells were grown in hypoxanthine, aminopterine and thymidine (HAT) selective medium and cloned by limiting dilution. Large scale of monoclonal antibodies was produced by mouse ascites production of mAb (in vivo) method. Monoclonal antibody was purified by chromatography. Then reactivity of these antibodies was evaluated in different immunological assays including ELISA, immunofluorescence (IF), western blot (WB) and flowcytometry. In this study, between five positive clone wells, two clones were chosen for limiting dilution. Limiting dilution product was one monoclone (3-D5 monoclone) with absorbance about 2. Isotype of this mAb was identified as IgG1 class with Kappa (κ) light chain. This antibody is highly specific and functional in biomedical applications such as ELISA, flowcytometry, immunofluorescence, and western blot assays.

Isolation of Human Colon Stem Cells Using Surface Expression of PTK7.

PubMed

Jung, Peter; Sommer, Christian; Barriga, Francisco M; Buczacki, Simon J; Hernando-Momblona, Xavier; Sevillano, Marta; Duran-Frigola, Miquel; Aloy, Patrick; Selbach, Matthias; Winton, Douglas J; Batlle, Eduard

2015-12-08

Insertion of reporter cassettes into the Lgr5 locus has enabled the characterization of mouse intestinal stem cells (ISCs). However, low cell surface abundance of LGR5 protein and lack of high-affinity anti-LGR5 antibodies represent a roadblock to efficiently isolate human colonic stem cells (hCoSCs). We set out to identify stem cell markers that would allow for purification of hCoSCs. In an unbiased approach, membrane-enriched protein fractions derived from in vitro human colonic organoids were analyzed by quantitative mass spectrometry. Protein tyrosine pseudokinase PTK7 specified a cell population within human colonic organoids characterized by highest self-renewal and re-seeding capacity. Antibodies recognizing the extracellular domain of PTK7 allowed us to isolate and expand hCoSCs directly from patient-derived mucosa samples. Human PTK7+ cells display features of canonical Lgr5+ ISCs and include a fraction of cells that undergo differentiation toward enteroendocrine lineage that resemble crypt label retaining cells (LRCs). Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Growth inhibition of tumor cells in vitro by using monoclonal antibodies against gonadotropin-releasing hormone receptor.

PubMed

Lee, Gregory; Ge, Bixia

2010-07-01

As the continuation of a previous study, synthetic peptides corresponding to the extracellular domains of human gonadotropin-releasing hormone (GnRH) receptor were used to generate additional monoclonal antibodies which were further characterized biochemically and immunologically. Among those identified to recognize GnRH receptor, monoclonal antibodies designated as GHR-103, GHR-106 and GHR-114 were found to exhibit high affinity (Kd < or = 1 x 10(-8) M) and specificity to GnRH receptor as judged by the whole cell binding immunoassay and Western blot assay. Both anti-GnRH receptor monoclonal antibodies and GnRH were shown to compete for the same binding site of GnRH receptor on the surface of cultured cancer cells. Growth inhibitions of cancer cells cultured in vitro were demonstrated by cellular apoptosis experiments (TUNEL and MTT assays) under different conditions of treatment with GHR-106 monoclonal antibody or GnRH analogs. It was generally observed that both GnRH I and GHR-106 effectively induce the apoptosis of cultured cancer cells as determined by TUNEL and MTT assays. Consistently, suppressions of gene expressions at mRNA levels were demonstrated with several ribosomal proteins (P0, P1, P2 and L37), when cancer cells were incubated with GnRH or GHR-106. The widespread expressions of GnRH receptor in almost all of the studied human cancer cell lines were also demonstrated by RT-PCR and Western blot assay, as well as indirect immunofluorescence assay with either of these monoclonal antibodies as the primary antibody. In view of the longer half life of antibodies as compared to that of GnRH or its analogs, anti-GnRH receptor monoclonal antibodies in humanized forms could function as GnRH analogs and serve as an ideal candidate of anti-cancer drugs for therapeutic treatments of various cancers in humans as well as for fertility regulations.

Novel BAFF-Receptor Antibody to Natively Folded Recombinant Protein Eliminates Drug-Resistant Human B-cell Malignancies In Vivo.

PubMed

Qin, Hong; Wei, Guowei; Sakamaki, Ippei; Dong, Zhenyuan; Cheng, Wesley A; Smith, D Lynne; Wen, Feng; Sun, Han; Kim, Kunhwa; Cha, Soungchul; Bover, Laura; Neelapu, Sattva S; Kwak, Larry W

2018-03-01

Purpose: mAbs such as anti-CD20 rituximab are proven therapies in B-cell malignancies, yet many patients develop resistance. Novel therapies against alternative targets are needed to circumvent resistance mechanisms. We sought to generate mAbs against human B-cell-activating factor receptor (BAFF-R/TNFRSF13C), which has not yet been targeted successfully for cancer therapy. Experimental Design: Novel mAbs were generated against BAFF-R, expressed as a natively folded cell surface immunogen on mouse fibroblast cells. Chimeric BAFF-R mAbs were developed and assessed for in vitro and in vivo monotherapy cytotoxicity. The chimeric mAbs were tested against human B-cell tumor lines, primary patient samples, and drug-resistant tumors. Results: Chimeric antibodies bound with high affinity to multiple human malignant B-cell lines and induced potent antibody-dependent cellular cytotoxicity (ADCC) against multiple subtypes of human lymphoma and leukemia, including primary tumors from patients who had relapsed after anti-CD20 therapy. Chimeric antibodies also induced ADCC against ibrutinib-resistant and rituximab-insensitive CD20-deficient variant lymphomas, respectively. Importantly, they demonstrated remarkable in vivo growth inhibition of drug-resistant tumor models in immunodeficient mice. Conclusions: Our method generated novel anti-BAFF-R antibody therapeutics with remarkable single-agent antitumor effects. We propose that these antibodies represent an effective new strategy for targeting and treating drug-resistant B-cell malignancies and warrant further development. Clin Cancer Res; 24(5); 1114-23. ©2017 AACR . ©2017 American Association for Cancer Research.

Monoclonal antibodies directed against surface molecules of multicell spheroids

NASA Technical Reports Server (NTRS)

Martinez, Andrew O.

1994-01-01

The objective of this project is to generate a library of monoclonial antibodies (MAbs) directed against surface molecules of tumor and transformed cells grown as multicell spheroids (MCS). These MCS are highly organized, 3-dimensional multicellular structures which exhibit many characteristics of in vivo organized tissues which are not found in conventional monolayer or suspension culture. In brief, MCS combine the relevance or organized tissues with in vitro methodology making the MCS a good model system to study the interactions of mammalian cells, and thereby provide a functional assay for surface adhesion molecules. This project also involves investigations of cell-cell interactions in a gravity-based environment. It will provide an important base of scientific information for future comparative studies on the effects of hypergravity and simulated microgravity environments on cell-cell interactions. This project also has the potential to yield important materials (e.g. cellular products) which may be useful for the diagnosis and/or treatment of certain human diseases. Moreover, this project supports the training of one undergraduate and one graduate student; thus, it will also assist in developing a pool of future scientists with research experience in gravitational biology research.

3D Plasma Nanotextured® Polymeric Surfaces for Protein or Antibody Arrays, and Biomolecule and Cell Patterning.

PubMed

Tsougeni, Katerina; Ellinas, Kosmas; Koukouvinos, George; Petrou, Panagiota S; Tserepi, Angeliki; Kakabakos, Sotirios E; Gogolides, Evangelos

2018-01-01

Plasma micro-nanotexturing is a generic technology for topographical and chemical modification of surfaces and their implementation in microfluidics and microarrays. Nanotextured surfaces with desirable chemical functionality (and wetting behavior) have shown excellent biomolecule immobilization and cell adhesion. Specifically, nanotextured hydrophilic areas show (a) strong binding of biomolecules and (b) strong adhesion of cells, while nanotextured superhydrophobic areas show null adsorption of (a) proteins and (b) cells. Here we describe the protocols for (a) biomolecule adsorption control on nanotextured surfaces for microarray fabrication and (b) cell adhesion on such surfaces. 3D plasma nanotextured® substrates are commercialized through Nanoplasmas private company, a spin-off of the National Centre for Scientific Research Demokritos.

Molecular Chaperone BiP Interacts with Borna Disease Virus Glycoprotein at the Cell Surface▿ †

PubMed Central

Honda, Tomoyuki; Horie, Masayuki; Daito, Takuji; Ikuta, Kazuyoshi; Tomonaga, Keizo

2009-01-01

Borna disease virus (BDV) is characterized by highly neurotropic infection. BDV enters its target cells using virus surface glycoprotein (G), but the cellular molecules mediating this process remain to be elucidated. We demonstrate here that the N-terminal product of G, GP1, interacts with the 78-kDa chaperone protein BiP. BiP was found at the surface of BDV-permissive cells, and anti-BiP antibody reduced BDV infection as well as GP1 binding to the cell surface. We also reveal that BiP localizes at the synapse of neurons. These results indicate that BiP may participate in the cell surface association of BDV. PMID:19776128

Cross-reactivity between the immunodominant determinant of the antigen I component of Streptococcus sobrinus SpaA protein and surface antigens from other members of the Streptococcus mutans group.

PubMed

Goldschmidt, R M; Curtiss, R

1990-07-01

Most members of the Streptococcus mutans group of microorganisms specify a major cell surface-associated protein, SpaA, that is defined by its antigenic properties. The region of the spaA gene from Streptococcus sobrinus 6715 encoding the immunodominant determinant of the major antigenic component (antigen I) of the SpaA protein has recently been characterized. This study examined whether recognition of the immunodominant determinant is independent of the immunized animal host and whether antibodies elicited by the immunodominant determinant cross-react with cell surface proteins from S. mutans of various serotypes. Mouse and rabbit antisera to the undenatured SpaA protein reacted similarly both with the immunodominant determinant and with other antigenic structures of the protein in Western immunoblots with SpaA polypeptides that were specified by spaA gene fragments expressed in recombinant Escherichia coli. This suggests that the antibody responses of inbred and outbred animals were similar. Furthermore, antibodies raised against both the S. sobrinus SpaA immunodominant determinant expressed by recombinant E. coli and the purified protein from S. sobrinus displayed similar strain specificities and protein band profiles towards cells surface proteins from S. mutans of various serotypes in immunodot and Western blot analyses, respectively. This suggests that for S. sobrinus serotype g, the immune response against the SpaA protein is governed by the immunodominant determinant of antigen I. In addition, it indicates that the SpaA protein domain containing the immunodominant determinant overlaps the domain conferring cross-reactivity to cell surface proteins of S. mutans of various serotypes.

Suppression of allo-human leucocyte antigen (HLA) antibodies secreted by B memory cells in vitro: intravenous immunoglobulin (IVIg) versus a monoclonal anti-HLA-E IgG that mimics HLA-I reactivities of IVIg.

PubMed

Zhu, D; Ravindranath, M H; Terasaki, P I; Miyazaki, T; Pham, T; Jucaud, V

2014-08-01

B memory cells remain in circulation and secrete alloantibodies without antigen exposure > 20 years after alloimmunization postpartum or by transplantation. These long-lived B cells are resistant to cytostatic drugs. Therapeutically, intravenous immunoglobulin (IVIg) is administered to reduce allo-human leucocyte antigen (HLA) antibodies pre- and post-transplantation, but the mechanism of reduction remains unclear. Recently, we reported that IVIg reacts with several HLA-I alleles and the HLA reactivity of IVIg is lost after its HLA-E reactivity is adsorbed out. Therefore, we have generated an anti-HLA-E monoclonal antibody that mimics the HLA-reactivity of IVIg to investigate whether this antibody suppresses IgG secretion, as does IVIg. B cells were purified from the blood of a woman in whose blood the B memory cells remained without antigen exposure > 20 years after postpartum alloimmunization. The B cells were stimulated with cytokines using a well-defined culture system. The anti-HLA-E monoclonal antibody (mAb) significantly suppressed the allo-HLA class-II IgG produced by the B cells, and that this suppression was far superior to that by IVIg. These findings were confirmed with HLA-I antibody secreted by the immortalized B cell line, developed from the blood of another alloimmunized woman. The binding affinity of the anti-HLA-E mAb for peptide sequences shared (i.e. shared epitopes) between HLA-E and other β2-microglobulin-free HLA heavy chains (open conformers) on the cell surface of B cells may act as a ligand and signal suppression of IgG production of activated B memory cells. We propose that anti-HLA-E monoclonal antibody may also be useful to suppress allo-HLA IgG production in vivo. © 2014 British Society for Immunology.

Movement disorders in paraneoplastic and autoimmune disease

PubMed Central

Panzer, Jessica; Dalmau, Josep

2013-01-01

Purpose of review The most relevant advances in immune-mediated movement disorders are described, with emphasis on the clinical–immunological associations, novel antigens, and treatment. Recent findings Many movement disorders previously considered idiopathic or degenerative are now recognized as immune-mediated. Some disorders are paraneoplastic, such as anti-CRMP5-associated chorea, anti-Ma2 hypokinesis and rigidity, anti-Yo cerebellar ataxia and tremor, and anti-Hu ataxia and pesudoathetosis. Other disorders such as Sydenham's chorea, or chorea related to systemic lupus erythematosus and antiphospholipid syndrome occur in association with multiple antibodies, are not paraneoplastic, and are triggered by molecular mimicry or unknown mechanisms. Recent studies have revealed a new category of disorders that can be paraneoplastic or not, and associate with antibodies against cell-surface or synaptic proteins. They include anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis, which may cause dyskinesias, chorea, ballismus or dystonia (NMDAR antibodies), the spectrum of Stiff-person syndrome/muscle rigidity (glutamic acid decarboxylase, amphiphysin, GABAA-receptor-associated protein, or glycine receptor antibodies), neuromyotonia (Caspr2 antibodies), and opsoclonus–myoclonus–ataxia (unknown antigens). Summary Neurologists should be aware that many movement disorders are immune-mediated. Recognition of these disorders is important because it may lead to the diagnosis of an occult cancer, and a substantial number of patients, mainly those with antibodies to cell-surface or synaptic proteins, respond to immunotherapy. PMID:21577108

Fungus-mediated biological synthesis of gold nanoparticles: potential in detection of liver cancer

PubMed Central

Chauhan, Arun; Zubair, Swaleha; Tufail, Saba; Sherwani, Asif; Sajid, Mohammad; Raman, Suri C; Azam, Amir; Owais, Mohammad

2011-01-01

Background Nanomaterials are considered to be the pre-eminent component of the rapidly advancing field of nanotechnology. However, developments in the biologically inspired synthesis of nanoparticles are still in their infancy and consequently attracting the attention of material scientists throughout the world. Keeping in mind the fact that microorganism-assisted synthesis of nanoparticles is a safe and economically viable prospect, in the current study we report Candida albicans-mediated biological synthesis of gold nanoparticles. Methods and results Transmission electron microscopy, atomic force microscopy, and various spectrophotometric analyses were performed to characterize the gold nanoparticles. The morphology of the synthesized gold particles depended on the abundance of C. albicans cytosolic extract. Transmission electron microscopy, nanophox particle analysis, and atomic force microscopy revealed the size of spherical gold nanoparticles to be in the range of 20–40 nm and nonspherical gold particles were found to be 60–80 nm. We also evaluated the potential of biogenic gold nanoparticles to probe liver cancer cells by conjugating them with liver cancer cell surface-specific antibodies. The antibody-conjugated gold particles were found to bind specifically to the surface antigens of the cancer cells. Conclusion The antibody-conjugated gold particles synthesized in this study could successfully differentiate normal cell populations from cancerous cells. PMID:22072868

Enhanced ADCC Activity of Affinity Maturated and Fc-Engineered Mini-Antibodies Directed against the AML Stem Cell Antigen CD96

PubMed Central

Kellner, Christian; Bräutigam, Joachim; Staudinger, Matthias; Schub, Natalie; Peipp, Matthias; Gramatzki, Martin; Humpe, Andreas

2012-01-01

CD96, a cell surface antigen recently described to be preferentially expressed on acute myeloid leukemia (AML) leukemic stem cells (LSC) may represent an interesting target structure for the development of antibody-based therapeutic approaches. The v-regions from the CD96-specific hybridoma TH-111 were isolated and used to generate a CD96-specific single chain fragment of the variable regions (scFv). An affinity maturated variant resulting in 4-fold enhanced CD96-binding was generated by random mutagenesis and stringent selection using phage display. The affinity maturated scFv CD96-S32F was used to generate bivalent mini-antibodies by genetically fusing an IgG1 wild type Fc region or a variant with enhanced CD16a binding. Antibody dependent cell-mediated cytotoxicity (ADCC) experiments revealed that Fc engineering was essential to trigger significant effector cell-mediated lysis when the wild type scFv was used. The mini-antibody variant generated by fusing the affinity-maturated scFv with the optimized Fc variant demonstrated the highest ADCC activity (2.3-fold enhancement in efficacy). In conclusion, our data provide proof of concept that CD96 could serve as a target structure for effector cell-mediated lysis and demonstrate that both enhancing affinity for CD96 and for CD16a resulted in mini-antibodies with the highest cytolytic potential. PMID:22879978

Establishment of a cell model for screening antibody drugs against rheumatoid arthritis with ADCC and CDC.

PubMed

Yan, Li; Hu, Rui; Tu, Song; Cheng, Wen-Jun; Zheng, Qiong; Wang, Jun-Wen; Kan, Wu-Sheng; Ren, Yi-Jun

2015-01-01

TNFα played a dominant role in the development and progression of rheumatoid arthritis (RA). Clinical trials proved the efficacies of anti-TNFα agents for curing RA. However, most researchers were concentrating on their abilities of neutralizing TNFα, the potencies of different anti-TNFα agents varied a lot due to the antibody-dependent cell-mediated cytotoxicity (ADCC) or complement dependent cytotoxicity (CDC). For better understanding and differentiating the potentiality of various candidate anti-TNF reagents at the stage of new drug research and development, present study established a cell model expressing the transmembrane TNFα for usage in in vitro ADCC or CDC assay, meanwhile, the assay protocol described here could provide guidelines for screening macromolecular antibody drugs. A stable cell subline bearing transmembrane TNFα was first established by conventional transfection method, the expression of transmembrane TNFα was approved by flow cytometer, and the performance of the stable subline in ADCC and CDC assay was evaluated, using human peripheral blood mononuclear cells as effector cells, and Adalimumab as the anti-TNFα reagent. The stable cell subline demonstrated high level of surface expression of transmembrane TNFα, and Adalimumab exerted both ADCC and CDC effects on this cell model. In conclusion, the stable cell line we established in present research could be used in ADCC or CDC assay for screening antibody drugs, which would provide in-depth understanding of the potencies of candidate antibody drugs in addition to the traditional TNFα neutralizing assay.

Inhibition of memory consolidation by antibodies against cell adhesion molecules after active avoidance conditioning in zebrafish.

PubMed

Pradel, G; Schachner, M; Schmidt, R

1999-05-01

Cell adhesion molecules are expected to play an important role in long-term storage of information in the central nervous system. Several of these glycoproteins, such as NCAM, L1, and the ependymins, express the HNK-1 carbohydrate structure, which is known to be involved in cell-cell and cell-matrix interactions. To investigate the contribution of the HNK-1 epitope and the secretory glycoproteins ependymins to memory formation in zebrafish (Brachydanio rerio), we developed an active avoidance conditioning paradigm. Zebrafish were trained in a shuttle-box to cross a hurdle, to avoid mild electric shocks following a conditioning light signal. One hour after acquisition of the task, zebrafish were injected intracerebroventricularly with monoclonal antibodies against the HNK-1 epitope or polyclonal antibodies against ependymins. Control fish received immunoglobulins G (IgGs) from nonimmune rat serum or the monoclonal antibody C183 against an unrelated cell-surface protein of the cyprinid brain. Two days later, injected zebrafish were tested for recall, and for quantitative evaluation a retention score (RS), ranging from 1.0 for immediate recall to 0.0, indicating no saving, was calculated. The average RS of anti-HNK-1-injected fish (RS = 0.30) and anti-ependymin-injected fish (0.24) were significantly different from the RS of uninjected fish (0.77), of controls injected with nonimmune serum IgGs (0.68), of C183-injected controls (0.78), and of overtrained fish injected with anti-HNK-1 antibodies (0.81). Anti-HNK-1 and anti-ependymin antibodies were characterized by Western blot analyses of subcellular brain fractions and immunohistochemical staining of the zebrafish optic tectum. Our data suggest that the antibodies influence cell recognition events at synaptic membranes and/or associated intracellular signaling cascades, and thereby block memory consolidation.

Felix Hoppe-Seyler Lecture 1997. Protective antibody responses against viruses.

PubMed

Zinkernagel, R M

1997-08-01

Neutralizing antibody responses against the acute cytopathic vesicular stomatitis virus (VSV) have been studied in mice to evaluate their general characteristics including specificity, self-/non-self discrimination and memory. IgM responses are generated very early, by day 3 to 4, in a T helper cell-independent fashion and without VSV having polyclonal activating capacities. The order of the glycoprotein tips on the virus envelope (multiple, 8-10 nm distance, paracrystalline) exhibiting the neutralizing determinants are key to this prompt response. These paracrystalline identical multimeric antigens are characteristic of infectious agents and are always reacted against by B cells. Self-antigens that are accessible to B cells in the intact host are either monomeric in serum or mobile multimers on cell surfaces; these configurations need contact dependent or contact independent T help, respectively. Because T help is tolerant against self-antigens, no anti-self B cell responses are usually induced against monomeric self-antigens. If collagen or DNA (rigid multimeric self-antigens) become accessible, however, they may become targets of auto-antibody responses. The antibody repertoire against VSV is partially contained in the germline and partially is generated by somatic mutation; they seem not to undergo affinity-maturation. In any case protection against lethal infection is dependent upon strictly T helper cell dependent IgG generated by day 6 to 7 and reaches a protective level of about 1-10 micrograms/ml. Interesting affinity/avidity and onrate above a minimal threshold are of no apparent advantage for protection in vivo. Maintenance of these antibody levels by antigen depots, and not the presence of memory B cells alone, is key to providing protective immunological memory. Collectively these data suggest that studying biologically important protective antibody responses may modify some of the parameters that have been defined by studying hapten specific antibody responses.

Differential localization of ErbB2 in different tissues of the rat female reproductive tract: implications for the use of specific antibodies for ErbB2 analysis.

PubMed

Idris, N; Carothers Carraway, C A; Carraway, K L

2001-11-01

ErbB2 has been implicated in numerous functions, including normal and aberrant development of a variety of tissues. Although no soluble ligand has been identified for ErbB2, we have recently shown that ASGP-2, the transmembrane subunit of the cell surface glycoprotein Muc4 (also called sialomucin complex, SMC), can act as an intramembrane ligand for ErbB2 and modulate its activity. Muc4/SMC is abundantly expressed at the apical surface of most epithelia of the rat female reproductive tract. Since Muc4/SMC can interact with ErbB2 when they are expressed in the same cell and membrane, we investigated whether these two proteins are co-expressed and co-localized in tissues of the female reproductive tract. Using an anti-ErbB2 antibody from Dako, we found moderate staining at the basolateral surface of the oviduct and also around the cell membrane of the most superficial and medial layers of the stratified epithelia of the vagina. In contrast, Neomarkers neu Ab1 antibody intensely stained the apical surface of the epithelium of the oviduct and the medial and basal layers of the stratified epithelia of the vagina, substantially overlapping the distribution of Muc4/SMC. Furthermore, Muc4/SMC and ErbB2 association in different tissues of the female reproductive tract was demonstrated by co-immunoprecipitation analysis. Interestingly, phosphorylated ErbB2 detected by anti-phospho-ErbB2 is primarily present at the apical surface of the oviduct. Thus, our results show that differentially localized forms of ErbB2 are recognized by different antibodies and raise interesting questions about the nature of the different forms of ErbB2, the mechanism for differential localization, and possible functions of ErbB2 in the female reproductive tract. They also raise a cautionary note about the use of different ErbB2 antibodies for expression and localization studies. Copyright 2001 Wiley-Liss, Inc.

Nonviral RNA transfection to transiently modify T cells with chimeric antigen receptors for adoptive therapy.

PubMed

Riet, Tobias; Holzinger, Astrid; Dörrie, Jan; Schaft, Niels; Schuler, Gerold; Abken, Hinrich

2013-01-01

Redirecting T cells with a chimeric antigen receptor (CAR) of predefined specificity showed remarkable efficacy in the adoptive therapy trials of malignant diseases. The CAR consists of a single chain fragment of variable region (scFv) antibody targeting domain covalently linked to the CD3ζ signalling domain of the T cell receptor complex to mediate T cell activation upon antigen engagement. By using an antibody-derived targeting domain a CAR can potentially redirect T cells towards any target expressed on the cell surface as long as a binding domain is available. Antibody-mediated targeting moreover circumvents MHC restriction of the targeted antigen, thereby broadening the potential of applicability of adoptive T cell therapy. While T cells were so far genetically modified by viral transduction, transient modification with a CAR by RNA transfection gained increasing interest during the last years. This chapter focuses on methods to modify human T cells from peripheral blood with a CAR by electroporation of in vitro transcribed RNA and to test modified T cells for function for use in adoptive immunotherapy.

Generation of a Highly Reactive Chicken-Derived Single-Chain Variable Fragment against Fusarium verticillioides by Phage Display

PubMed Central

Hu, Zu-Quan; Liu, Jin-Long; Li, He-Ping; Xing, Shu; Xue, Sheng; Zhang, Jing-Bo; Wang, Jian-Hua; Nölke, Greta; Liao, Yu-Cai

2012-01-01

Fusarium verticillioides is the primary causal agent of Fusarium ear and kernel rot in maize, producing fumonisin mycotoxins that are toxic to humans and domestic animals. Rapid detection and monitoring of fumonisin-producing fungi are pivotally important for the prevention of mycotoxins from entering into food/feed products. Chicken-derived single-chain variable fragments (scFvs) against cell wall-bound proteins from F. verticillioides were isolated from an immunocompetent phage display library. Comparative phage enzyme-linked immunosorbant assays (ELISAs) and sequencing analyses identified four different scFv antibodies with high sensitivity. Soluble antibody ELISAs identified two highly sensitive scFv antibodies, FvCA3 and FvCA4, with the latter being slightly more sensitive. Three-dimensional modeling revealed that the FvCA4 may hold a better overall structure with CDRH3, CDRL1 and CDRL3 centered in the core region of antibody surface compared with that of other scFvs. Immunofluorescence labeling revealed that the binding of FvCA4 antibody was localized to the cell walls of conidiospores and hyphae of F. verticillioides, confirming the specificity of this antibody for a surface target. This scFv antibody was able to detect the fungal mycelium as low as 10−2 μg/mL and contaminating mycelium at a quantity of 10−2 mg/g maize. This is the first report that scFv antibodies derived from phage display have a wide application for rapid and accurate detection and monitoring of fumonisin-producing pathogens in agricultural samples. PMID:22837678

Blocking pulmonary ICAM-1 expression ameliorates lung injury in established diet-induced pancreatitis.

PubMed

Lundberg, A H; Fukatsu, K; Gaber, L; Callicutt, S; Kotb, M; Wilcox, H; Kudsk, K; Gaber, A O

2001-02-01

To determine whether blocking the cell surface expression of intracellular adhesion molecules (ICAM-1) in established severe acute pancreatitis (AP) would ameliorate pulmonary injury. Lung injury in AP is in part mediated by infiltrating leukocytes, which are directed to lung tissue by ICAM-l. The authors' laboratory has previously demonstrated that AP results in overproduction of inflammatory cytokines, upregulation of pulmonary ICAM-1 expression, and a concomitant infiltration of neutrophils, which results in lung injury. Young female mice were fed a choline-deficient/ethionine-supplemented diet to induce AP and were treated with a blocking dose of monoclonal antibody specific to the ICAM-1 receptor. Antibody treatment was administered at 72, 96, and 120 hours after beginning the diet, and all animals were killed at 144 hours. The degree of pancreatitis was evaluated by serum biochemical and tumor necrosis factor alpha levels as well as histology. The dual radiolabeled monoclonal antibody method was used to quantitate ICAM-1 cell surface expression in pulmonary tissue. Lung injury was assessed histologically and by determining lung microvascular permeability by measuring accumulated 125I-radiolabeled albumin. Pulmonary neutrophil sequestration was determined by the myeloperoxidase assay. All mice developed severe AP, and pancreatic injury was equally severe in both treated and untreated groups. Pulmonary ICAM-1 expression was significantly upregulated in animals with AP compared with controls. Treatment with a blocking dose of anti-ICAM-1 antibody after the induction of AP resulted in inhibited ICAM-1 cell surface expression to near control levels. Compared to untreated animals with AP, mice treated with anti-ICAM-1 mice had significantly reduced histologic lung injury and neutrophil sequestration, and a decreased microvascular permeability by more than twofold. These results demonstrate for the first time that treatment targeting the cell surface expression of ICAM-1 after the induction of AP ameliorates pulmonary injury, even in the face of severe pancreatic disease.

Binding of antibodies to the extractable nuclear antigens SS-A/Ro and SS-B/La is induced on the surface of human keratinocytes by ultraviolet light (UVL): Implications for the pathogenesis of photosensitive cutaneous lupus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furukawa, F.; Kashihara-Sawami, M.; Lyons, M.B.

1990-01-01

Autoantibodies to the non-histone nucleoprotein antigens SS-A/Ro, SS-B/La, and RNP are highly associated with photosensitive cutaneous lupus erythematosus (LE). In order to better understand the potential mechanisms of ultraviolet (UV) light on photosensitivity in patients with cutaneous LE, we designed immunopathologic in vitro and in vivo experiments to evaluate the effects of UV on the binding of such autoantibodies to the surface of human keratinocytes, one major target of immunologic damage in photosensitive LE. Short-term 2% paraformaldehyde fixation of suspensions of cultured human keratinocytes previously incubated with monospecific antiserum probes enabled the detection of ENA expression on the cell surfacemore » by flow-cytometry analysis. UVB light (280-320 nm) induced the binding of monospecific antibody probes for SS-A/Ro and SS-B/La on keratinocytes in a dose-dependent pattern with maximal induction observed at the dose of 200 mJ/cm2 UVB. Binding of SS-A/Ro, SS-B/La, and RNP antibody was augmented strongly, but binding of anti-Sm was very weak. In contrast, UVA (320-400 nm) light had no effect on the induction of binding of these antibody probes. Identical results were seen by standard immunofluorescence techniques. Hydroxyurea-treated keratinocytes showed similar induction of those antigens by UVB irradiation, which suggested that ENA expression on cultured keratinocytes by UVB were cell-cycle independent. Tunicamycin, an inhibitor of glycosylation of proteins, reduced UVB light effect on the SS-A/Ro and SS-B/La antigen's expression. These in vitro FACS analyses revealed that ENA augmentation on the keratinocyte cell surface was dose dependent, UVB dependent, glycosylation dependent, and cell-cycle independent. In vivo ENA augmentation on the keratinocyte surface was examined in suction blister epidermal roofs.« less

Noninvasive in vivo multispectral optoacoustic imaging of apoptosis in triple negative breast cancer using indocyanine green conjugated phosphatidylserine monoclonal antibody

NASA Astrophysics Data System (ADS)

Kannadorai, Ravi Kumar; Udumala, Sunil Kumar; Sidney, Yu Wing Kwong

2016-12-01

Noninvasive and nonradioactive imaging modality to track and image apoptosis during chemotherapy of triple negative breast cancer is much needed for an effective treatment plan. Phosphatidylserine (PS) is a biomarker transiently exposed on the outer surface of the cells during apoptosis. Its externalization occurs within a few hours of an apoptotic stimulus by a chemotherapy drug and leads to presentation of millions of phospholipid molecules per apoptotic cell on the cell surface. This makes PS an abundant and accessible target for apoptosis imaging. In the current work, we show that PS monoclonal antibody tagged with indocyanine green (ICG) can help to track and image apoptosis using multispectral optoacoustic tomography in vivo. When compared to saline control, the doxorubicin treated group showed a significant increase in uptake of ICG-PS monoclonal antibody in triple negative breast tumor xenografted in NCr nude female mice. Day 5 posttreatment had the highest optoacoustic signal in the tumor region, indicating maximum apoptosis and the tumor subsequently shrank. Since multispectral optoacoustic imaging does not involve the use of radioactivity, the longer the circulatory time of the PS antibody can be exploited to monitor apoptosis over a period of time without multiple injections of commonly used imaging probes such as Tc-99m Annexin V or F-18 ML10. The proposed apoptosis imaging technique involving multispectral optoacoustic tomography, monoclonal antibody, and near-infrared absorbing fluorescent marker can be an effective tool for imaging apoptosis and treatment planning.

A Bivalent, Chimeric Rabies Virus Expressing Simian Immunodeficiency Virus Envelope Induces Multifunctional Antibody Responses.

PubMed

Dunkel, Amber; Shen, Shixue; LaBranche, Celia C; Montefiori, David; McGettigan, James P

2015-11-01

We previously showed that a matrix (M) gene-deleted rabies virus (RABV)-based vaccine (RABV-ΔM) is highly immunogenic and induces potent B cell responses in the context of RABV infection. We speculated that RABV-ΔM expressing HIV proteins would also induce potent B cell responses against HIV antigens. As a prerequisite to future studies in nonhuman primates, we completed immunogenicity studies in mice to confirm the ability of RABV-ΔM to induce polyfunctional B cell responses in the context of HIV. To that end, the envelope protein from the mac239 strain of SIV (SIVmac239Env) was cloned into RABV-ΔM, resulting in RABV-ΔM-Env. Infectious virus was recovered following standard methods and propagated on baby hamster kidney cells stably expressing RABV M [>10(7) focus forming units (ffu)/ml]. Western blot analysis of cell lysates or of purified virions confirmed Env expression on the surface of infected cells and within virus particles, respectively. Positive neutralization activity against a neutralization-sensitive SIV strain and to a lesser extent against a neutralization-resistant SIV strain was detected in mice after a single intramuscular inoculation with RABV-ΔM-Env. The quality, but not quantity, of the antibody response was enhanced via boosting with recombinant gp130 or RABV-ΔM-Env as measured by an increase in antibody avidity and a skewing toward a Th1-type antibody response. We also show that an intradermal inoculation induces higher antibodies than an intramuscular or intranasal inoculation. An intradermal inoculation of RABV-ΔM-Env followed by a boost inoculation with recombinant gp130 produced anti-SIV antibodies with neutralizing and nonneutralizing antibody (nNAb) effector functions. Together, RABV-ΔM-Env induces B cells to secrete antibodies against SIV with the potential to clear both "free" and cell-associated virus. Strategies capable of eliciting both NAbs as well as nNAbs might help to improve the efficacy of HIV-1 vaccines.

Nucleolin inhibits Fas ligand binding and suppresses Fas-mediated apoptosis in vivo via a surface nucleolin-Fas complex.

PubMed

Wise, Jillian F; Berkova, Zuzana; Mathur, Rohit; Zhu, Haifeng; Braun, Frank K; Tao, Rong-Hua; Sabichi, Anita L; Ao, Xue; Maeng, Hoyoung; Samaniego, Felipe

2013-06-06

Resistance to Fas-mediated apoptosis is associated with poor cancer outcomes and chemoresistance. To elucidate potential mechanisms of defective Fas signaling, we screened primary lymphoma cell extracts for Fas-associated proteins that would have the potential to regulate Fas signaling. An activation-resistant Fas complex selectively included nucleolin. We confirmed the presence of nucleolin-Fas complexes in B-cell lymphoma cells and primary tissues, and the absence of such complexes in B-lymphocytes from healthy donors. RNA-binding domain 4 and the glycine/arginine-rich domain of nucleolin were essential for its association with Fas. Nucleolin colocalized with Fas on the surface of B-cell lymphoma cells. Nucleolin knockdown sensitized BJAB cells to Fas ligand (FasL)-induced and Fas agonistic antibody-induced apoptosis through enhanced binding, suggesting that nucleolin blocks the FasL-Fas interaction. Mice transfected with nucleolin were protected from the lethal effects of agonistic anti-mouse Fas antibody (Jo2) and had lower rates of hepatocyte apoptosis, compared with vector and a non-Fas-binding mutant of nucleolin. Our results show that cell surface nucleolin binds Fas, inhibits ligand binding, and thus prevents induction of Fas-mediated apoptosis in B-cell lymphomas and may serve as a new therapeutic target.

Nucleolin inhibits Fas ligand binding and suppresses Fas-mediated apoptosis in vivo via a surface nucleolin-Fas complex

PubMed Central

Wise, Jillian F.; Berkova, Zuzana; Mathur, Rohit; Zhu, Haifeng; Braun, Frank K.; Tao, Rong-Hua; Sabichi, Anita L.; Ao, Xue; Maeng, Hoyoung

2013-01-01

Resistance to Fas-mediated apoptosis is associated with poor cancer outcomes and chemoresistance. To elucidate potential mechanisms of defective Fas signaling, we screened primary lymphoma cell extracts for Fas-associated proteins that would have the potential to regulate Fas signaling. An activation-resistant Fas complex selectively included nucleolin. We confirmed the presence of nucleolin-Fas complexes in B-cell lymphoma cells and primary tissues, and the absence of such complexes in B-lymphocytes from healthy donors. RNA-binding domain 4 and the glycine/arginine-rich domain of nucleolin were essential for its association with Fas. Nucleolin colocalized with Fas on the surface of B-cell lymphoma cells. Nucleolin knockdown sensitized BJAB cells to Fas ligand (FasL)-induced and Fas agonistic antibody-induced apoptosis through enhanced binding, suggesting that nucleolin blocks the FasL–Fas interaction. Mice transfected with nucleolin were protected from the lethal effects of agonistic anti-mouse Fas antibody (Jo2) and had lower rates of hepatocyte apoptosis, compared with vector and a non-Fas-binding mutant of nucleolin. Our results show that cell surface nucleolin binds Fas, inhibits ligand binding, and thus prevents induction of Fas-mediated apoptosis in B-cell lymphomas and may serve as a new therapeutic target. PMID:23599269

Kinetics of antigen binding to arrays of antibodies in different sized spots

NASA Technical Reports Server (NTRS)

Sapsford, K. E.; Liron, Z.; Shubin, Y. S.; Ligler, F. S.

2001-01-01

A fluorescence-based array biosensor has been developed which can measure the binding kinetics of an antigen to an immobilized antibody in real time. A patterned array of antibodies immobilized on the surface of a planar waveguide was used to capture a Cy5-labeled antigen present in a solution that was continuously flowed over the surface. The CCD image of the waveguide was monitored continuously for 25 min. The resulting exponential rise in fluorescence signal was determined by image analysis software and fitted to a reaction-limited kinetics model, giving a kf of 3.6 x 10(5) M(-1) s(-1). Different spot sizes were then patterned on the surface of the waveguide using either a PDMS flow cell or laser exposure, producing width sizes ranging from 80 to 1145 microm. It was demonstrated that under flow conditions, the reduction of spot size did not alter the association rate of the antigen with immobilized antibody; however, as the spot width decreased to < 200 nm, the signal intensity also decreased.

B-lymphoma cells escape rituximab-triggered elimination by NK cells through increased HLA class I expression.

PubMed

Borgerding, Andrea; Hasenkamp, Justin; Engelke, Michael; Burkhart, Nina; Trümper, Lorenz; Wienands, Jürgen; Glass, Bertram

2010-03-01

Antibody-dependent cellular cytotoxicity (ADCC) by natural killer (NK) cells is a major effector mechanism of the monoclonal anti-CD20 antibody rituximab in eliminating B-cell lymphomas. Resistance to this treatment occurs, although CD20 antigen is expressed on the tumor cells. A model of ADCC was established by stimulating human bulk NK cells and inhibitory killer immunoglobulin receptor (KIR)-defined NK cells from human leukocyte antigen (HLA)-typed donors. NK-cell activation was triggered via stimulation of the Fc receptor with immunoglobulin G aggregates, rituximab-labeled HLA-defined CD20-positive B-lymphoblast cell lines or CD20-positive B-lymphoma cell lines. The effect of KIR ligation by anti-KIR antibodies and HLA, the HLA expression density and rituximab concentrations on the efficacy of ADCC were analyzed in granzyme B ELISPOT measuring NK-cell activation and fluorescein-activated cell sorting cytotoxicity assay. HLA, but not CD20 expression density correlated with NK-cell activity against rituximab-labeled targets. ADCC was increased or decreased following HLA shielding or KIR activation by anti-KIR antibodies, respectively. Herein we show that rituximab-induced ADCC is attenuated upon ligation of KIR by HLA molecules expressed on human B-lymphoma target cells. Moreover, anti-KIR antibodies do not only block KIR/HLA interactions, but display agonistic effects at the KIR, which has to be considered for therapeutical applications. KIR activation and HLA expression density are critical determinants for the efficacy of rituximab treatment. An explanation for the failure of rituximab treatment may be the protection of the tumor cells from ADCC by inhibiting NK-cell function with their surface HLA. Copyright 2010 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.

Antibody Against Integrin Lymphocyte Function-Associated Antigen 1 Inhibits HIV Type 1 Infection in Primary Cells Through Caspase-8-Mediated Apoptosis

PubMed Central

Walker, Tiffany N.; Cimakasky, Lisa M.; Coleman, Ebony M.; Madison, M. Nia

2013-01-01

Abstract HIV-1 infection induces formation of a virological synapse wherein CD4, chemokine receptors, and cell-adhesion molecules such as lymphocyte function-associated antigen 1 (LFA-1) form localized domains on the cell surface. Studies show that LFA-1 on the surface of HIV-1 particles retains its adhesion function and enhances virus attachment to susceptible cells by binding its counterreceptor intercellular adhesion molecule 1 (ICAM-1). This virus–cell interaction augments virus infectivity by facilitating binding and entry events. In this study, we demonstrate that inhibition of the LFA-1/ICAM-1 interaction by a monoclonal antibody leads to decreased virus production and spread in association with increased apoptosis of HIV-infected primary T cells. The data indicate that the LFA-1/ICAM-1 interaction may limit apoptosis in HIV-1-infected T cells. This phenomenon appears similar to anoikis wherein epithelial cells are protected from apoptosis conferred by ligand-bound integrins. These results have implications for further understanding HIV pathogenesis and replication in peripheral compartments and lymphoid organs. PMID:22697794

Breaking the color barrier - a multi-selective antibody reporter offers innovative strategies of fluorescence detection.

PubMed

Gallo, Eugenio; Jarvik, Jonathan W

2017-08-01

A novel bi-partite fluorescence platform exploits the high affinity and selectivity of antibody scaffolds to capture and activate small-molecule fluorogens. In this report, we investigated the property of multi-selectivity activation by a single antibody against diverse cyanine family fluorogens. Our fluorescence screen identified three cell-impermeant fluorogens, each with unique emission spectra (blue, green and red) and nanomolar affinities. Most importantly, as a protein fusion tag to G-protein-coupled receptors, the antibody biosensor retained full activity - displaying bright fluorogen signals with minimal background on live cells. Because fluorogen-activating antibodies interact with their target ligands via non-covalent interactions, we were able to perform advanced multi-color detection strategies on live cells, previously difficult or impossible with conventional reporters. We found that by fine-tuning the concentrations of the different color fluorogen molecules in solution, a user may interchange the fluorescence signal (onset versus offset), execute real-time signal exchange via fluorogen competition, measure multi-channel fluorescence via co-labeling, and assess real-time cell surface receptor traffic via pulse-chase experiments. Thus, here we inform of an innovative reporter technology based on tri-color signal that allows user-defined fluorescence tuning in live-cell applications. © 2017. Published by The Company of Biologists Ltd.

Antibody-Mediated Inhibition of Ricin Toxin Retrograde Transport

PubMed Central

Yermakova, Anastasiya; Klokk, Tove Irene; Cole, Richard; Sandvig, Kirsten; Mantis, Nicholas J.

2014-01-01

ABSTRACT Ricin is a member of the ubiquitous family of plant and bacterial AB toxins that gain entry into the cytosol of host cells through receptor-mediated endocytosis and retrograde traffic through the trans-Golgi network (TGN) and endoplasmic reticulum (ER). While a few ricin toxin-specific neutralizing monoclonal antibodies (MAbs) have been identified, the mechanisms by which these antibodies prevent toxin-induced cell death are largely unknown. Using immunofluorescence confocal microscopy and a TGN-specific sulfation assay, we demonstrate that 24B11, a MAb against ricin’s binding subunit (RTB), associates with ricin in solution or when prebound to cell surfaces and then markedly enhances toxin uptake into host cells. Following endocytosis, however, toxin-antibody complexes failed to reach the TGN; instead, they were shunted to Rab7-positive late endosomes and LAMP-1-positive lysosomes. Monovalent 24B11 Fab fragments also interfered with toxin retrograde transport, indicating that neither cross-linking of membrane glycoproteins/glycolipids nor the recently identified intracellular Fc receptor is required to derail ricin en route to the TGN. Identification of the mechanism(s) by which antibodies like 24B11 neutralize ricin will advance our fundamental understanding of protein trafficking in mammalian cells and may lead to the discovery of new classes of toxin inhibitors and therapeutics for biodefense and emerging infectious diseases. PMID:24713323

A cell sorter with modified bamboo charcoal for the efficient selection of specific antibody-producing hybridomas.

PubMed

Lin, Chien-Chen; Ni, Mei-Hui; Chang, Yu-Chung; Yeh, Hsiu-Lun; Lin, Feng-Huei

2010-11-01

Monoclonal antibodies (mAbs) have been proven useful in research and clinical applications. However, the generation of mAbs by conventional hybridoma technology is time-, cost- and labor-consuming. Here we developed a simplified procedure for efficient generation and selection of antibody-producing hybridomas within 1 h, using a particular cell sorter design, a cytoflow reactor-based cell sorter (CBCS) which consists mainly of the "cytoflow reactor" that comprises two components, a reaction chamber and a glass tubing for air and medium exchange by gravity, and the "sorting material", human EGFR-conjugated bamboo charcoal, for specific B-cell enrichment. The high surface area and porous structure of bamboo charcoal greatly increased cell density and protein production. Moreover, from Raman, FT-IR spectroscopy and IFA analysis, the carboxylation and immobilization of bamboo charcoal can be introduced easily by nitric acid treatment and conjugated handily with human EGFR using EDC/NHS. Other evidences, such as IFA, showed that the specific hybridomas generated in this study could secrete specific anti-human EGFR antibodies. Our design allows the production of mAbs while avoiding time-consuming steps, such as large numbers of limiting dilutions and screening assays, and demonstrates that the CBCS could be a powerful tool for monoclonal antibody production. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Nanostructure and force spectroscopy analysis of human peripheral blood CD4+ T cells using atomic force microscopy.

PubMed

Hu, Mingqian; Wang, Jiongkun; Cai, Jiye; Wu, Yangzhe; Wang, Xiaoping

2008-09-12

To date, nanoscale imaging of the morphological changes and adhesion force of CD4(+) T cells during in vitro activation remains largely unreported. In this study, we used atomic force microscopy (AFM) to study the morphological changes and specific binding forces in resting and activated human peripheral blood CD4(+) T cells. The AFM images revealed that the volume of activated CD4(+) T cells increased and the ultrastructure of these cells also became complex. Using a functionalized AFM tip, the strength of the specific binding force of the CD4 antigen-antibody interaction was found to be approximately three times that of the unspecific force. The adhesion forces were not randomly distributed over the surface of a single activated CD4(+) T cell, indicated that the CD4 molecules concentrated into nanodomains. The magnitude of the adhesion force of the CD4 antigen-antibody interaction did not change markedly with the activation time. Multiple bonds involved in the CD4 antigen-antibody interaction were measured at different activation times. These results suggest that the adhesion force involved in the CD4 antigen-antibody interaction is highly selective and of high affinity.

Host Immune Response to Influenza A Virus Infection.

PubMed

Chen, Xiaoyong; Liu, Shasha; Goraya, Mohsan Ullah; Maarouf, Mohamed; Huang, Shile; Chen, Ji-Long

2018-01-01

Influenza A viruses (IAVs) are contagious pathogens responsible for severe respiratory infection in humans and animals worldwide. Upon detection of IAV infection, host immune system aims to defend against and clear the viral infection. Innate immune system is comprised of physical barriers (mucus and collectins), various phagocytic cells, group of cytokines, interferons (IFNs), and IFN-stimulated genes, which provide first line of defense against IAV infection. The adaptive immunity is mediated by B cells and T cells, characterized with antigen-specific memory cells, capturing and neutralizing the pathogen. The humoral immune response functions through hemagglutinin-specific circulating antibodies to neutralize IAV. In addition, antibodies can bind to the surface of infected cells and induce antibody-dependent cell-mediated cytotoxicity or complement activation. Although there are neutralizing antibodies against the virus, cellular immunity also plays a crucial role in the fight against IAVs. On the other hand, IAVs have developed multiple strategies to escape from host immune surveillance for successful replication. In this review, we discuss how immune system, especially innate immune system and critical molecules are involved in the antiviral defense against IAVs. In addition, we highlight how IAVs antagonize different immune responses to achieve a successful infection.

Immunocytochemical localization of muscarinic, adrenergic and AT1 receptors.

PubMed

Schulze, W; Fu, M L

1996-01-01

By indirect immunofluorescence and post-embedding EM gold technique, the localization of alpha 1-adrenergic, M2-muscarinic and angiotensin II receptor-I (AT1) were determinated. With antipeptide antibodies directed against the second extracellular loops of all three receptors, these receptors were found to be localized at the sarcolemma of adult rat cardiomyocytes and at the surface membranes of cultivated neonatal heart cells. Additionally, M2 receptors were localized along T-tubule membranes of both rat and human adult cardiomyocytes. alpha 1-Adrenergic receptors were found intracellular near the surface of atrial granules (ANF-granules). By using M2 and alpha 1-adrenergic receptor antibodies the strongest fluorescence was found in the right atrium of the rat. Besides the localization in cardiomyocytes, AT1 receptors were also localized in outer plasma membranes and the endoplasmic reticulum of fibroblasts, and the surface of smooth muscle cells of the major arteries and veins. Likewise, the muscarinic M2 receptors were found along the outer membranes of endothelial cells from capillaries and endocardium.

Monoclonal antibodies directed against surface molecules of multicell spheroids

NASA Technical Reports Server (NTRS)

Martinez, Andrew O.

1994-01-01

The objective of this project is to generate a library of monoclonal antibodies (MAbs) directed against surface molecules of tumor and transformed cells grown as multicell spheroids (MCS). These MCS are highly organized, 3-dimensional multicellular structures which exhibit many characteristics of in vivo organized tissues not found in conventional monolayer or suspension culture. Therefore MCS make better in vitro model systems to study the interactions of mammalian cells, and provide a functional assay for surface adhesion molecules. This project also involves investigations of cell-cell interactions in a gravity-based environment. It will provide a base of scientific information necessary to expand the focus of the project in future years to microgravity and hypergravity-based environments. This project also has the potential to yield important materials (e.g., cellular products) which may prove useful in the diagnosis and/or treatment of certain human diseases. Moreover, this project supports the training of both undergraduate and graduate students; thus, it will assist in developing a pool of future scientists with research experience in an area (gravitational biology) of interest to NASA.

A novel multiplex bead-based platform highlights the diversity of extracellular vesicles

PubMed Central

Koliha, Nina; Wiencek, Yvonne; Heider, Ute; Jüngst, Christian; Kladt, Nikolay; Krauthäuser, Susanne; Johnston, Ian C. D.; Bosio, Andreas; Schauss, Astrid; Wild, Stefan

2016-01-01

The surface protein composition of extracellular vesicles (EVs) is related to the originating cell and may play a role in vesicle function. Knowledge of the protein content of individual EVs is still limited because of the technical challenges to analyse small vesicles. Here, we introduce a novel multiplex bead-based platform to investigate up to 39 different surface markers in one sample. The combination of capture antibody beads with fluorescently labelled detection antibodies allows the analysis of EVs that carry surface markers recognized by both antibodies. This new method enables an easy screening of surface markers on populations of EVs. By combining different capture and detection antibodies, additional information on relative expression levels and potential vesicle subpopulations is gained. We also established a protocol to visualize individual EVs by stimulated emission depletion (STED) microscopy. Thereby, markers on single EVs can be detected by fluorophore-conjugated antibodies. We used the multiplex platform and STED microscopy to show for the first time that NK cell–derived EVs and platelet-derived EVs are devoid of CD9 or CD81, respectively, and that EVs isolated from activated B cells comprise different EV subpopulations. We speculate that, according to our STED data, tetraspanins might not be homogenously distributed but may mostly appear as clusters on EV subpopulations. Finally, we demonstrate that EV mixtures can be separated by magnetic beads and analysed subsequently with the multiplex platform. Both the multiplex bead-based platform and STED microscopy revealed subpopulations of EVs that have been indistinguishable by most analysis tools used so far. We expect that an in-depth view on EV heterogeneity will contribute to our understanding of different EVs and functions. PMID:26901056

Immunotherapy of cancer: from monoclonal to oligoclonal cocktails of anti‐cancer antibodies: IUPHAR Review 18

PubMed Central

Carvalho, Silvia; Levi‐Schaffer, Francesca; Sela, Michael

2016-01-01

Antibody‐based therapy of cancer employs monoclonal antibodies (mAbs) specific to soluble ligands, membrane antigens of T‐lymphocytes or proteins located at the surface of cancer cells. The latter mAbs are often combined with cytotoxic regimens, because they block survival of residual fractions of tumours that evade therapy‐induced cell death. Antibodies, along with kinase inhibitors, have become in the last decade the mainstay of oncological pharmacology. However, partial and transient responses, as well as emergence of tumour resistance, currently limit clinical application of mAbs. To overcome these hurdles, oligoclonal antibody mixtures are being tested in animal models and in clinical trials. The first homo‐combination of two mAbs, each engaging a distinct site of HER2, an oncogenic receptor tyrosine kinase (RTK), has been approved for treatment of breast cancer. Likewise, a hetero‐combination of antibodies to two distinct T‐cell antigens, PD1 and CTLA4, has been approved for treatment of melanoma. In a similar vein, additive or synergistic anti‐tumour effects observed in animal models have prompted clinical testing of hetero‐combinations of antibodies simultaneously engaging distinct RTKs. We discuss the promise of antibody cocktails reminiscent of currently used mixtures of chemotherapeutics and highlight mechanisms potentially underlying their enhanced clinical efficacy. PMID:26833433

High Epstein-Barr Virus Load and Genomic Diversity Are Associated with Generation of gp350-Specific Neutralizing Antibodies following Acute Infectious Mononucleosis

PubMed Central

Weiss, Eric R.; Alter, Galit; Ogembo, Javier Gordon; Henderson, Jennifer L.; Tabak, Barbara; Bakiş, Yasin; Somasundaran, Mohan; Garber, Manuel; Selin, Liisa

2016-01-01

ABSTRACT The Epstein-Barr virus (EBV) gp350 glycoprotein interacts with the cellular receptor to mediate viral entry and is thought to be the major target for neutralizing antibodies. To better understand the role of EBV-specific antibodies in the control of viral replication and the evolution of sequence diversity, we measured EBV gp350-specific antibody responses and sequenced the gp350 gene in samples obtained from individuals experiencing primary EBV infection (acute infectious mononucleosis [AIM]) and again 6 months later (during convalescence [CONV]). EBV gp350-specific IgG was detected in the sera of 17 (71%) of 24 individuals at the time of AIM and all 24 (100%) individuals during CONV; binding antibody titers increased from AIM through CONV, reaching levels equivalent to those in age-matched, chronically infected individuals. Antibody-dependent cell-mediated phagocytosis (ADCP) was rarely detected during AIM (4 of 24 individuals; 17%) but was commonly detected during CONV (19 of 24 individuals; 79%). The majority (83%) of samples taken during AIM neutralized infection of primary B cells; all samples obtained at 6 months postdiagnosis neutralized EBV infection of cultured and primary target cells. Deep sequencing revealed interpatient gp350 sequence variation but conservation of the CR2-binding site. The levels of gp350-specific neutralizing activity directly correlated with higher peripheral blood EBV DNA levels during AIM and a greater evolution of diversity in gp350 nucleotide sequences from AIM to CONV. In summary, we conclude that the viral load and EBV gp350 diversity during early infection are associated with the development of neutralizing antibody responses following AIM. IMPORTANCE Antibodies against viral surface proteins can blunt the spread of viral infection by coating viral particles, mediating uptake by immune cells, or blocking interaction with host cell receptors, making them a desirable component of a sterilizing vaccine. The EBV surface protein gp350 is a major target for antibodies. We report the detection of EBV gp350-specific antibodies capable of neutralizing EBV infection in vitro. The majority of gp350-directed vaccines focus on glycoproteins from lab-adapted strains, which may poorly reflect primary viral envelope diversity. We report some of the first primary gp350 sequences, noting that the gp350 host receptor binding site is remarkably stable across patients and time. However, changes in overall gene diversity were detectable during infection. Patients with higher peripheral blood viral loads in primary infection and greater changes in viral diversity generated more efficient antibodies. Our findings provide insight into the generation of functional antibodies, necessary for vaccine development. PMID:27733645

High Epstein-Barr Virus Load and Genomic Diversity Are Associated with Generation of gp350-Specific Neutralizing Antibodies following Acute Infectious Mononucleosis.

PubMed

Weiss, Eric R; Alter, Galit; Ogembo, Javier Gordon; Henderson, Jennifer L; Tabak, Barbara; Bakiş, Yasin; Somasundaran, Mohan; Garber, Manuel; Selin, Liisa; Luzuriaga, Katherine

2017-01-01

The Epstein-Barr virus (EBV) gp350 glycoprotein interacts with the cellular receptor to mediate viral entry and is thought to be the major target for neutralizing antibodies. To better understand the role of EBV-specific antibodies in the control of viral replication and the evolution of sequence diversity, we measured EBV gp350-specific antibody responses and sequenced the gp350 gene in samples obtained from individuals experiencing primary EBV infection (acute infectious mononucleosis [AIM]) and again 6 months later (during convalescence [CONV]). EBV gp350-specific IgG was detected in the sera of 17 (71%) of 24 individuals at the time of AIM and all 24 (100%) individuals during CONV; binding antibody titers increased from AIM through CONV, reaching levels equivalent to those in age-matched, chronically infected individuals. Antibody-dependent cell-mediated phagocytosis (ADCP) was rarely detected during AIM (4 of 24 individuals; 17%) but was commonly detected during CONV (19 of 24 individuals; 79%). The majority (83%) of samples taken during AIM neutralized infection of primary B cells; all samples obtained at 6 months postdiagnosis neutralized EBV infection of cultured and primary target cells. Deep sequencing revealed interpatient gp350 sequence variation but conservation of the CR2-binding site. The levels of gp350-specific neutralizing activity directly correlated with higher peripheral blood EBV DNA levels during AIM and a greater evolution of diversity in gp350 nucleotide sequences from AIM to CONV. In summary, we conclude that the viral load and EBV gp350 diversity during early infection are associated with the development of neutralizing antibody responses following AIM. Antibodies against viral surface proteins can blunt the spread of viral infection by coating viral particles, mediating uptake by immune cells, or blocking interaction with host cell receptors, making them a desirable component of a sterilizing vaccine. The EBV surface protein gp350 is a major target for antibodies. We report the detection of EBV gp350-specific antibodies capable of neutralizing EBV infection in vitro The majority of gp350-directed vaccines focus on glycoproteins from lab-adapted strains, which may poorly reflect primary viral envelope diversity. We report some of the first primary gp350 sequences, noting that the gp350 host receptor binding site is remarkably stable across patients and time. However, changes in overall gene diversity were detectable during infection. Patients with higher peripheral blood viral loads in primary infection and greater changes in viral diversity generated more efficient antibodies. Our findings provide insight into the generation of functional antibodies, necessary for vaccine development. Copyright © 2016 American Society for Microbiology.

Neem leaf glycoprotein enhances carcinoembryonic antigen presentation of dendritic cells to T and B cells for induction of anti-tumor immunity by allowing generation of immune effector/memory response.

PubMed

Sarkar, Koustav; Goswami, Shyamal; Roy, Soumyabrata; Mallick, Atanu; Chakraborty, Krishnendu; Bose, Anamika; Baral, Rathindranath

2010-08-01

Vaccination with neem leaf glycoprotein matured carcinoembryonic antigen (CEA) pulsed dendritic cells (DCs) enhances antigen-specific humoral and cellular immunity against CEA and restricts the growth of CEA(+) murine tumors. NLGP helps better CEA uptake, processing and presentation to T/B cells. This vaccination (DCNLGPCEA) elicits mitogen induced and CEA specific T cell proliferation, IFN gamma secretion and induces specific cytotoxic reactions to CEA(+) colon tumor cells. In addition to T cell response, DCNLGPCEA vaccine generates anti-CEA antibody response, which is principally IgG2a in nature. This antibody participates in cytotoxicity of CEA(+) cells in antibody-dependent manner. This strong anti-CEA cellular and humoral immunity protects mice from tumor development and these mice remained tumor free following second tumor inoculation, indicating generation of effector memory response. Evaluation of underlying mechanism suggests vaccination generates strong CEA specific CTL and antibody response that can completely prevent the tumor growth following adoptive transfer. In support, significant upregulation of CD44 on the surface of lymphocytes from DCNLGPCEA immunized mice was noticed with a substantial reduction in L-selectin (CD62L). (c) 2010 Elsevier B.V. All rights reserved.

Surface Molecules Released by Trypanosoma cruzi Metacyclic Forms Downregulate Host Cell Invasion

PubMed Central

Clemente, Tatiana Mordente; Cortez, Cristian; Novaes, Antônio da Silva; Yoshida, Nobuko

2016-01-01

Background The question whether metacylic trypomastigote (MT) forms of different T. cruzi strains differentially release surface molecules, and how they affect host cell invasion, remains to be fully clarified. We addressed that question using T. cruzi strains that differ widely in the ability to invade cells. Methodology/Principal Findings Metacyclic forms were incubated at 37°C for 1 h in complete D10 medium or in nutrient-deprived PBS containing Ca2+ and Mg2+ (PBS++). The conditioned medium (CM), collected after parasite centrifugation, was used for cell invasion assays and Western blot analysis, using monoclonal antibodies directed to gp82 and gp90, the MT surface molecules that promote and negatively regulate invasion, respectively. CM of poorly invasive G strain (G-CM) contained high amounts of gp90 and gp82, either in vesicles or as soluble molecules. CM of highly invasive CL strain (CL-CM) contained gp90 and gp82 at very low levels. HeLa cells were incubated for 1 h with CL strain MT in D10, in absence or in the presence of G-CM or CL-CM. Parasite invasion was significantly inhibited by G-CM, but not by CL-CM. As G strain MT invasion rate in D10 is very low, assays with this strain were performed in PBS++, which induces invasion-promoting lysosome-spreading. G-CM, but not CL-CM, significantly inhibited G strain internalization, effect that was counteracted by preincubating G-CM with an anti-gp90 monoclonal antibody or anti-gp82 polyclonal antibody that do not recognize live MT. G strain CM generated in PBS++ contained much lower amounts of gp90 and gp82 as compared to CM produced in D10, and exhibited lower inhibitory effect on host cell invasion. Conclusion/Significance Our data suggest that the surface molecules spontaneously released by MT impair parasite-host cell interaction, gp82 presumably competing with the molecule expressed on MT surface for the host cell receptor, and gp90 further contributing to down modulate invasion. PMID:27483135

Anti-B-Cell Therapies in Autoimmune Neurological Diseases: Rationale and Efficacy Trials.

PubMed

Alexopoulos, Harry; Biba, Angie; Dalakas, Marinos C

2016-01-01

B cells have an ever-increasing role in the etiopathology of a number of autoimmune neurological disorders, acting as antibody-producing cells and, most importantly, as sensors, coordinators, and regulators of the immune response. B cells, among other functions, regulate the T-cell activation process through their participation in antigen presentation and production of cytokines. The availability of monoclonal antibodies or fusion proteins against B-cell surface molecules or B-cell trophic factors bestows a rational approach for treating autoimmune neurological disorders, even when T cells are the main effector cells. This review summarizes basic aspects of B-cell biology, discusses the role(s) of B cells in neurological autoimmunity, and presents anti-B-cell drugs that are either currently on the market or are expected to be available in the near future for treating neurological autoimmune disorders.

Unexpected cross-reactivity of anti-cathepsin B antibodies leads to uncertainties regarding the mechanism of action of anti-CD20 monoclonal antibody GA101.

PubMed

Chien, Wei Wen; Niogret, Charlène; Jugé, Romain; Lionnard, Loïc; Cornut-Thibaut, Aurélie; Kucharczak, Jérôme; Savina, Ariel; Salles, Gilles; Aouacheria, Abdel

2017-04-01

GA101, also known as obinutuzumab or Gazyva (Gazyvaro), is a glycoengineered type II humanized antibody that targets the CD20 antigen expressed at the surface of B-cells. This novel anti-CD20 antibody is currently assessed in clinical trials with promising results as a single agent or as part of therapeutic combinations for the treatment of B-cell malignancies. Detailed understanding of the mechanisms of GA101-induced cell death is needed to get insight into possible resistance mechanisms occurring in patients. Although multiple in vitro and in vivo mechanisms have been suggested to describe the effects of GA101 on B-cells, currently available data are ambiguous. The aim of our study was to clarify the cellular mechanisms involved in GA101-induced cell death in vitro, and more particularly the respective roles played by lysosomal and mitochondrial membrane permeabilization. Our results confirm previous reports suggesting that GA101 triggers homotypic adhesion and caspase-independent cell death, two processes that are dependent on actin remodeling and involve the production of reactive oxygen species. With respect to lysosomal membrane permeabilization (LMP), our data suggest that lack of specificity of available antibodies directed against cathepsin B may have confounded previously published results, possibly challenging current LMP-driven model of GA101 action mode. Copyright © 2017 Elsevier Ltd. All rights reserved.

Localized gene delivery using antibody tethered adenovirus from polyurethane heart valve cusps and intra-aortic implants.

PubMed

Stachelek, S J; Song, C; Alferiev, I; Defelice, S; Cui, X; Connolly, J M; Bianco, R W; Levy, R J

2004-01-01

The present study investigated a novel approach for gene therapy of heart valve disease and vascular disorders. We formulated and characterized implantable polyurethane films that could also function as gene delivery systems through the surface attachment of replication defective adenoviruses using an anti-adenovirus antibody tethering mechanism. Our hypothesis was that we could achieve site-specific gene delivery to cells interacting with these polyurethane implants, and thereby demonstrate the potential for intravascular devices that could also function as gene delivery platforms for therapeutic vectors. Previous research by our group has demonstrated that polyurethane elastomers can be derivatized post-polymerization through a series of chemical reactions activating the hard segment amide groups with alkyl bromine residues, which can enable a wide variety of subsequent chemical modifications. Furthermore, prior research by our group investigating gene delivery intravascular stents has shown that collagen-coated balloon expandable stents can be configured with anti-adenovirus antibodies via thiol-based chemistry, and can then tether adenoviral vectors at doses that lead to high levels of localized arterial neointima expression, but with virtually no distal spread of vector. Thus, we sought to create two-device configurations for our investigations building on this previous research. (1) Polyurethane films coated with Type I collagen were thiol activated to permit covalent attachment of anti-adenovirus antibodies to enable gene delivery via vector tethering. (2) We also formulated polyurethane films with direct covalent attachment of anti-adenovirus antibodies to polyurethane hard segments derivatized with alkyl-thiol groups, thereby also enabling tethering of replication-defective adenoviruses. Both formulations demonstrated highly localized and efficient transduction in cell culture studies with rat arterial smooth muscle cells. In vivo experiments with collagen-coated polyurethane films investigated an abdominal aorta implant model in pigs using a button configuration that simulated the blood contacting environment of a vascular graft. One week explants of the collagen-coated polyurethane films demonstrated 14.3+/-2.5% of neointimal cells on the surface of the implant transduced with green fluorescent protein - adenovirus (AdGFP) vector loadings of 1 x 10(8) PFU. PCR studies demonstrated no detectable vector DNA in blood or distal organs. Similarly, polyurethane films with direct attachment of antivector antibodies to the surface were used in sheep pulmonary valve leaflet replacement studies, simulating the blood contacting environment of a prosthetic heart valve cusp. Polyurethane films with antibody tethered AdGFP vector (10(8) PFU) demonstrated 25.1+/-5.7% of attached cells transduced in these 1 week studies, with no detectable vector DNA in blood or distal organs. In vivo GFP expression was confirmed with immunohistochemistry. It is concluded that site-specific intravascular delivery of adenoviral vectors for gene therapy can be achieved with polyurethane implants utilizing the antivector antibody tethering mechanism.

Immune complexes formed following the binding of anti-platelet factor 4 (CXCL4) antibodies to CXCL4 stimulate human neutrophil activation and cell adhesion.

PubMed

Xiao, Zhihua; Visentin, Gian P; Dayananda, Kannayakanahalli M; Neelamegham, Sriram

2008-08-15

We tested the possibility that immune complexes formed following platelet factor 4 (PF4/CXCL4) binding to anti-PF4 antibody can stimulate neutrophil activation, similar to previous reports with platelets. Monoclonal Abs against PF4 and IgG from a heparin-induced thrombocytopenia (HIT) patient were applied. We observed that although PF4 or anti-PF4 antibody alone did not alter neutrophil function, costimulation with both reagents resulted in approximately 3-fold increase in cell surface Mac-1 expression, enhanced cell adhesion via L-selectin and CD18 integrins, and degranulation of secondary and tertiary granules. The level of Mac-1 up-regulation peaked at an intermediate PF4 dose, suggesting that functional response varies with antigen-antibody stoichiometry. PF4 binding to neutrophils was blocked by chondroitinase ABC. Cell activation was inhibited by both chondroitinase ABC and anti-CD32/FcgammaRII blocking mAb, IV.3. Confocal microscopy demonstrated that immune complexes colocalize with CD32a. Studies with HIT IgG demonstrated that neutrophils could be activated in the absence of exogenous heparin. These data, together, show that leukocyte surface chondroitin sulfates promote neutrophil activation by enhancing immune-complex binding to CD32a. Studies with recombinant PF4 suggest a role for arginine 49 in stabilizing PF4-chondroitin binding. Neutrophils activated via this mechanism may contribute to thrombosis and inflammation in patients mounting an immune response to PF4-heparin.

Role of PTPase LAR in EGF Receptor in the Mammary Gland

DTIC Science & Technology

2003-06-01

saturating amounts of E-cadherin antibody (HECD-1) also led to a rapid and pronounced loss of cellular LAR. In contrast, mimicking cell surface E-cadherin...associates with LAR and is a substrate in vitro. With the saturating amounts of E-cadherin antibody (HECD-1) also led implication that LAR may play a role in...leucocyte common antigen-related cipitating antibody was pre-bound to Protein G-Sepharose beads phosphatase (LAR) associates with the N-terminus of fl

Combination of two insulin-like growth factor-I receptor inhibitory antibodies targeting distinct epitopes leads to an enhanced antitumor response.

PubMed

Dong, Jianying; Demarest, Stephen J; Sereno, Arlene; Tamraz, Susan; Langley, Emma; Doern, Adam; Snipas, Tracey; Perron, Keli; Joseph, Ingrid; Glaser, Scott M; Ho, Steffan N; Reff, Mitchell E; Hariharan, Kandasamy

2010-09-01

The insulin-like growth factor-I receptor (IGF-IR) is a cell surface receptor tyrosine kinase that mediates cell survival signaling and supports tumor progression in multiple tumor types. We identified a spectrum of inhibitory IGF-IR antibodies with diverse binding epitopes and ligand-blocking properties. By binding distinct inhibitory epitopes, two of these antibodies, BIIB4 and BIIB5, block both IGF-I and IGF-II binding to IGF-IR using competitive and allosteric mechanisms, respectively. Here, we explored the inhibitory effects of combining BIIB4 and BIIB5. In biochemical assays, the combination of BIIB4 and BIIB5 improved both the potency and extent of IGF-I and IGF-II blockade compared with either antibody alone. In tumor cells, the combination of BIIB4 and BIIB5 accelerated IGF-IR downregulation and more efficiently inhibited IGF-IR activation as well as downstream signaling, particularly AKT phosphorylation. In several carcinoma cell lines, the antibody combination more effectively inhibited ligand-driven cell growth than either BIIB4 or BIIB5 alone. Notably, the enhanced tumor growth-inhibitory activity of the BIIB4 and BIIB5 combination was much more pronounced at high ligand concentrations, where the individual antibodies exhibited substantially reduced activity. Compared with single antibodies, the BIIB4 and BIIB5 combination also significantly further enhanced the antitumor activity of the epidermal growth factor receptor inhibitor erlotinib and the mTOR inhibitor rapamycin. Moreover, in osteosarcoma and hepatocellular carcinoma xenograft models, the BIIB4 and BIIB5 combination significantly reduced tumor growth to a greater degree than each single antibody. Taken together, our results suggest that targeting multiple distinct inhibitory epitopes on IGF-IR may be a more effective strategy of affecting the IGF-IR pathway in cancer.

MUC1-Targeted Cancer Cell Photothermal Ablation Using Bioinspired Gold Nanorods.

PubMed

Zelasko-Leon, Daria C; Fuentes, Christina M; Messersmith, Phillip B

2015-01-01

Recent studies have highlighted the overexpression of mucin 1 (MUC1) in various epithelial carcinomas and its role in tumorigenesis. These mucins present a novel targeting opportunity for nanoparticle-mediated photothermal cancer treatments due to their unique antenna-like extracellular extension. In this study, MUC1 antibodies and albumin were immobilized onto the surface of gold nanorods using a "primer" of polydopamine (PD), a molecular mimic of catechol- and amine-rich mussel adhesive proteins. PD forms an adhesive platform for the deposition of albumin and MUC1 antibodies, achieving a surface that is stable, bioinert and biofunctional. Two-photon luminescence confocal and darkfield scattering imaging revealed targeting of MUC1-BSA-PD-NRs to MUC1+ MCF-7 breast cancer and SCC-15 squamous cell carcinoma cells lines. Treated cells were exposed to a laser encompassing the near-infrared AuNR longitudinal surface plasmon and assessed for photothermal ablation. MUC1-BSA-PD-NRs substantially decreased cell viability in photoirradiated MCF-7 cell lines vs. MUC1- MDA-MB-231 breast cancer cells (p < 0.005). Agents exhibited no cytotoxicity in the absence of photothermal treatment. The facile nature of the coating method, combined with targeting and photoablation efficacy, are attractive features of these candidate cancer nanotherapeutics.

Absence of Activation-induced Cytidine Deaminase, a Regulator of Class Switch Recombination and Hypermutation in B Cells, Suppresses Aorta Allograft Vasculopathy in Mice.

PubMed

Nakanishi, Tomonori; Xu, Xiaoyan; Wynn, Carmen; Yamada, Toshiko; Pan, Fan; Erickson, Laurie; Teo, Haeman; Nakagawa, Terry; Masunaga, Taro; Abe, Jumpei; Akamatsu, Masahiko; Tamura, Kouichi; Jiang, Hongsi

2015-08-01

Antibody-mediated rejection is caused in part by increasing circulation/production of donor-specific antibody (DSA). Activation-induced cytidine deaminase (AID) is a key regulator of class switch recombination and somatic hypermutation of immunoglobulin in B cells, yet its role in antibody-mediated transplant rejection remains unclear. We show here that AID deficiency in mice enables suppression of allograft vasculopathy (AV) after aorta transplantation, a DSA-mediated process. Splenocytes from C57BL/6 J (B6) AID(−/−) mice were used for determining in vitro proliferation responses, alloreactivity, cell surface marker expression, and antibody production. BALB/c mouse aortas were transplanted into B6 AID(−/−) mice with or without FK506 treatment. Blood and aorta grafts were harvested on day 30 after transplantation and were subjected to DSA, histological, and immunohistological analyses. The AID(−/−) splenocytes were comparable to wild type splenocytes in proliferation responses, alloreactivity, and expression of cell surface markers in vitro. However, they completely failed to produce immunoglobulin G, although they were not impaired in immunoglobulin M production relative to controls. Furthermore, BALB/c aorta grafts from B6 AID(−/−) recipient mice on day 30 after transplantation showed reduced signs of AV compared to the grafts from B6 wild type recipient mice which had severe vascular intimal hyperplasia, interstitial fibrosis, and inflammation. Treatment with FK506 produced a synergistic effect in the grafts from AID(−/−) recipients with further reduction of intimal hyperplasia and fibrosis scores. The AID deficiency inhibits DSA-mediated AV after aorta transplantation in mice. We propose that AID could be a novel molecular target for controlling antibody-mediated rejection in organ transplantation.

Aptamer-Based Methods for Detection of Circulating Tumor Cells and Their Potential for Personalized Diagnostics.

PubMed

Zamay, Anna S; Zamay, Galina S; Kolovskaya, Olga S; Zamay, Tatiana N; Berezovski, Maxim V

2017-01-01

Cancer diagnostics and treatment monitoring rely on sensing and counting of rare cells such as cancer circulating tumor cells (CTCs) in blood. Many analytical techniques have been developed to reliably detect and quantify CTCs using unique physical shape and size of tumor cells and/or distinctive patterns of cell surface biomarkers. Main problems of CTC bioanalysis are in the small number of cells that are present in the circulation and heterogeneity of CTCs. In this chapter, we describe recent progress towards the selection and application of synthetic DNA or RNA aptamers to capture and detect CTCs in blood. Antibody-based approaches for cell isolation and purification are limited because of an antibody's negative effect on cell viability and purity. Aptamers transform cell isolation technology, because they bind and release cells on-demand. The unique feature of anti-CTC aptamers is that the aptamers are selected for cell surface biomarkers in their native state, and conformation without previous knowledge of their biomarkers. Once aptamers are produced, they can be used to identify CTC biomarkers using mass spectrometry. The biomarkers and corresponding aptamers can be exploited to improve cancer diagnostics and therapies .

Single-domain antibodies that compete with the natural ligand fibroblast growth factor block the internalization of the fibroblast growth factor receptor 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veggiani, Gianluca; Ossolengo, Giuseppe; Aliprandi, Marisa

2011-05-20

Highlights: {yields} Recombinant antibodies for FGFR1 were isolated from a llama naive library in VHH format. {yields} These antibodies compete with the natural ligand FGF-2 for the same epitope on FGFR1. {yields} The antibody competition inhibits the FGF-2-dependent internalization of FGFR1. -- Abstract: Single-domain antibodies in VHH format specific for fibroblast growth factor receptor 1 (FGFR1) were isolated from a phage-display llama naive library. In particular, phage elution in the presence of the natural receptor ligand fibroblast growth factor (FGF) allowed for the identification of recombinant antibodies that compete with FGF for the same region on the receptor surface. Thesemore » antibodies posses a relatively low affinity for FGFR1 and were never identified when unspecific elution conditions favoring highly affine binders were applied to panning procedures. Two populations of competitive antibodies were identified that labeled specifically the receptor-expressing cells in immunofluorescence and recognize distinct epitopes. Antibodies from both populations effectively prevented FGF-dependent internalization and nuclear accumulation of the receptor in cultured cells. This achievement indicates that these antibodies have a capacity to modulate the receptor physiology and, therefore, constitute powerful reagents for basic research and a potential lead for therapeutic applications.« less

ERAP1 reduces accumulation of aberrant and disulfide-linked forms of HLA-B27 on the cell surface.

PubMed

Tran, Tri M; Hong, Sohee; Edwan, Jehad H; Colbert, Robert A

2016-06-01

Endoplasmic reticulum (ER) aminopeptidase 1 (ERAP1) variants contribute to the risk of ankylosing spondylitis in HLA-B27 positive individuals, implying a disease-related interaction between these gene products. The aim of this study was to determine whether reduced ERAP1 expression would alter the cell surface expression of HLA-B27 and the formation of aberrant disulfide-linked forms that have been implicated in the pathogenesis of spondyloarthritis. ERAP1 expression was knocked down in monocytic U937 cells expressing HLA-B27 and endogenous HLA class I. The effect of ERAP1 knockdown on the accumulation HLA-B alleles (B18, B51, and B27) was assessed using immunoprecipitation, isoelectric focusing, and immunoblotting, as well as flow cytometry with antibodies specific for different forms of HLA-B27. Cell surface expression of aberrant disulfide-linked HLA-B27 dimers was assessed by immunoprecipitation and electrophoresis on non-reducing polyacrylamide gels. ERAP1 knockdown increased the accumulation of HLA-B27 on the cell surface including disulfide-linked dimers, but had no effect on levels of HLA-B18 or -B51. Antibodies with unique specificity for HLA-B27 confirmed increased cell surface expression of complexes shown previously to contain long peptides. IFN-γ treatment resulted in striking increases in the expression of disulfide-linked HLA-B27 heavy chains, even in cells with normal ERAP1 expression. Our results suggest that normal levels of ERAP1 reduce the accumulation of aberrant and disulfide-linked forms of HLA-B27 in monocytes, and thus help to maintain the integrity of cell surface HLA-B27 complexes. Published by Elsevier Ltd.

ERAP1 Reduces Accumulation of Aberrant and Disulfide-Linked Forms of HLA-B27 on the Cell Surface

PubMed Central

Tran, Tri; Hong, Sohee; Edwan, Jehad; Colbert, Robert A.

2016-01-01

Objective Endoplasmic reticulum (ER) aminopeptidase 1 (ERAP1) variants contribute to the risk of ankylosing spondylitis in HLA-B27 positive individuals, implying a disease-related interaction between these gene products. The aim of this study was to determine whether reduced ERAP1 expression would alter the cell surface expression of HLA-B27 and the formation of aberrant disulfide-linked forms that have been implicated in the pathogenesis of spondyloarthritis. Methods ERAP1 expression was knocked down in monocytic U937 cells expressing HLA-B27 and endogenous HLA class I. The effect of ERAP1 knockdown on the accumulation HLA-B alleles (B18, B51, and B27) was assessed using immunoprecipitation, isoelectric focusing, and immunoblotting, as well as flow cytometry with antibodies specific for different forms of HLA-B27. Cell surface expression of aberrant disulfide-linked HLA-B27 dimers was assessed by immunoprecipitation and electrophoresis on non-reducing polyacrylamide gels. Results ERAP1 knockdown increased the accumulation of HLA-B27 on the cell surface including disulfide-linked dimers, but had no effect on levels of HLA-B18 or -B51. Antibodies with unique specificity for HLA-B27 confirmed increased cell surface expression of complexes shown previously to contain long peptides. IFN-γ treatment resulted in striking increases in the expression of disulfide-linked HLA-B27 heavy chains, even in cells with normal ERAP1 expression. Conclusions Our results suggest that normal levels of ERAP1 reduce the accumulation of aberrant and disulfide-linked forms of HLA-B27 in monocytes, and thus help to maintain the integrity of cell surface HLA-B27 complexes. PMID:27107845

Comparison of detection methods for cell surface globotriaosylceramide.

PubMed

Kim, Minji; Binnington, Beth; Sakac, Darinka; Fernandes, Kimberly R; Shi, Sheryl P; Lingwood, Clifford A; Branch, Donald R

2011-08-31

The cell surface-expressed glycosphingolipid (GSL), globotriaosylceramide (Gb(3)), is becoming increasingly important and is widely studied in the areas of verotoxin (VT)-mediated cytotoxicity, human immunodeficiency virus (HIV) infection, immunology and cancer. However, despite its diverse roles and implications, an optimized detection method for cell surface Gb(3) has not been determined. GSLs are differentially organized in the plasma membrane which can affect their availability for protein binding. To examine various detection methods for cell surface Gb(3), we compared four reagents for use in flow cytometry analysis. A natural ligand (VT1B) and three different monoclonal antibodies (mAbs) were optimized and tested on various human cell lines for Gb(3) detection. A differential detection pattern of cell surface Gb(3) expression, which was influenced by the choice of reagent, was observed. Two mAb were found to be suboptimal. However, two other methods were found to be useful as defined by their high percentage of positivity and mean fluorescence intensity (MFI) values. Rat IgM anti-Gb(3) mAb (clone 38-13) using phycoerythrin-conjugated secondary antibody was found to be the most specific detection method while the use of VT1B conjugated to Alexa488 fluorochrome was found to be the most sensitive; showing a rare crossreactivity only when Gb(4) expression was highly elevated. The findings of this study demonstrate the variability in detection of Gb(3) depending on the reagent and cell target used and emphasize the importance of selecting an optimal methodology in studies for the detection of cell surface expression of Gb(3). Copyright © 2011 Elsevier B.V. All rights reserved.

B cell recognition of the conserved HIV-1 co-receptor binding site is altered by endogenous primate CD4.

PubMed

Forsell, Mattias N E; Dey, Barna; Mörner, Andreas; Svehla, Krisha; O'dell, Sijy; Högerkorp, Carl-Magnus; Voss, Gerald; Thorstensson, Rigmor; Shaw, George M; Mascola, John R; Karlsson Hedestam, Gunilla B; Wyatt, Richard T

2008-10-03

The surface HIV-1 exterior envelope glycoprotein, gp120, binds to CD4 on the target cell surface to induce the co-receptor binding site on gp120 as the initial step in the entry process. The binding site is comprised of a highly conserved region on the gp120 core, as well as elements of the third variable region (V3). Antibodies against the co-receptor binding site are abundantly elicited during natural infection of humans, but the mechanism of elicitation has remained undefined. In this study, we investigate the requirements for elicitation of co-receptor binding site antibodies by inoculating rabbits, monkeys and human-CD4 transgenic (huCD4) rabbits with envelope glycoprotein (Env) trimers possessing high affinity for primate CD4. A cross-species comparison of the antibody responses showed that similar HIV-1 neutralization breadth was elicited by Env trimers in monkeys relative to wild-type (WT) rabbits. In contrast, antibodies against the co-receptor site on gp120 were elicited only in monkeys and huCD4 rabbits, but not in the WT rabbits. This was supported by the detection of high-titer co-receptor antibodies in all sera from a set derived from human volunteers inoculated with recombinant gp120. These findings strongly suggest that complexes between Env and (high-affinity) primate CD4 formed in vivo are responsible for the elicitation of the co-receptor-site-directed antibodies. They also imply that the naïve B cell receptor repertoire does not recognize the gp120 co-receptor site in the absence of CD4 and illustrate that conformational stabilization, imparted by primary receptor interaction, can alter the immunogenicity of a type 1 viral membrane protein.

Antibody specific epitope prediction-emergence of a new paradigm.

PubMed

Sela-Culang, Inbal; Ofran, Yanay; Peters, Bjoern

2015-04-01

The development of accurate tools for predicting B-cell epitopes is important but difficult. Traditional methods have examined which regions in an antigen are likely binding sites of an antibody. However, it is becoming increasingly clear that most antigen surface residues will be able to bind one or more of the myriad of possible antibodies. In recent years, new approaches have emerged for predicting an epitope for a specific antibody, utilizing information encoded in antibody sequence or structure. Applying such antibody-specific predictions to groups of antibodies in combination with easily obtainable experimental data improves the performance of epitope predictions. We expect that further advances of such tools will be possible with the integration of immunoglobulin repertoire sequencing data. Copyright © 2015 Elsevier B.V. All rights reserved.

Human Anti-Lipopolysaccharid (LPS) antibodies against Legionella with high species specificity.

PubMed

Kuhn, Philipp; Thiem, Stefanie; Steinert, Michael; Purvis, Duncan; Lugmayr, Veronika; Treutlein, Ulrich; Plobner, Lutz; Leiser, Robert-Matthias; Hust, Michael; Dübel, Stefan

2017-07-19

Legionella are Gram-negative bacteria that are ubiquitously present in natural and man-made water reservoirs. When humans inhale aerosolized water contaminated with Legionella, alveolar macrophages can be infected, which may lead to a life-threatening pneumonia called Legionnaires' disease. Due to the universal distribution of Legionella in water and their potential threat to human health, the Legionella concentration in water for human use must be strictly monitored, which is difficult since the standard detection still relies on lengthy cultivation and analysis of bacterial morphology. In this study, an antibody against L. pneumophila has been generated from the naïve human HAL antibody libraries by phage-display for the first time. The panning was performed on whole bacterial cells in order to select antibodies that bind specifically to the cell surface of untreated Legionella. The bacterial cell wall component lipopolysaccharide (LPS) was identified as the target structure. Specific binding to the important pathogenic L. pneumophila strains Corby, Philadelphia-1 and Knoxville was observed, while no binding was detected to seven members of the families Enterobacteriaceae, Pseudomonadaceae or Clostridiaceae. Production of this antibody in the recombinant scFv-Fc format using either a murine or a human Fc part allowed the set-up of a sandwich-ELISA for detection of Legionella cells. The scFv-Fc construct proved to be very stable, even when stored for several weeks at elevated temperatures. A sensitivity limit of 4,000 cells was achieved. The scFv-Fc antibody pair was integrated on a biosensor, demonstrating the specific and fast detection of L. pneumophila on a portable device. With this system, 10,000 Legionella cells were detected within 35 min. Combined with a water filtration/concentration system, this antibody may be developed into a promising reagent for rapid on-site Legionella monitoring.

Binding diversity of antibodies against external and internal epitopes of the multidrug resistance gene product P-glycoprotein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehne, G.; De Angelis, P.; Clausen, O.P.F.

1995-07-01

P-glycoprotein (Pgp) is a trans-membraneous protein that is associated with multidrug resistance (MDR) in human cancer, including hepatocellular carcinomas and leukemia. There is no consensus regarding methods of choice for analysis of Pgp expression, and development of reliable analytical methods is now essential. We have studied the Pgp expression in human hepatoma and leukemia cell lines using flow cytometry. The aim of the study was to compare binding properties of anti-Pgp antibodies reacting with surface (MRK16, UIC2) and cytoplasmic (C219, JSB-1) epitopes to assess which antibody performed best with respect to fluorescence discrimination. By histogram subtraction the fractions of resistantmore » human hepatoma cells positive for Pgp were 99% (MRK16), 97% (UIC2), 77% (USB-1), and 51% (C219), demonstrating variations in antibody reactivity. The resolution in detecting decreasing levels of Pgp in hepatoma cells was superior for the externally binding antibodies, showing that there is a correlation between antibody reactivity and fluorescence discrimination. Similar results were obtained for parental and resistant KG1a human leukemia cell lines. The Pgp epitopes remained reactive to the anti-Pgp MAbs after methanol fixation and cryopreservation. By dual parameter flow cytometry it was shown that Pgp expression in viable cells may be assessed together with uptake of epirubicin, which was low in cells expressing high levels of Pgp and vice versa. In conclusion, all tested antibodies proved useful for flow cytometric detection of high levels of Pgp, but the externally binding ones were superior in detection of low and variable levels of Pgp. 36 refs., 8 figs., 1 tab.« less

Ratio of Circulating IFNγ (+) "Th17 Cells" in Memory Th Cells Is Inversely Correlated with the Titer of Anti-CCP Antibodies in Early-Onset Rheumatoid Arthritis Patients Based on Flow Cytometry Methods of the Human Immunology Project.

PubMed

Kotake, Shigeru; Nanke, Yuki; Yago, Toru; Kawamoto, Manabu; Kobashigawa, Tsuyoshi; Yamanaka, Hisashi

2016-01-01

Rheumatoid arthritis (RA) is a systemic autoimmune disease with chronic joint inflammation characterized by activated T cells. IL-17 and Th17 cells play important roles in the pathogenesis of RA. Recently, plasticity in helper T cells has been demonstrated; Th17 cells can convert to Th1 cells. However, it remains to be elucidated whether this conversion occurs in the early phase of RA. Here, we validated the methods of the Human Immunology Project using only the cell-surface marker through measuring the actual expression of IL-17 and IFNγ. We also evaluated the expression of CD161 in human Th17 cells. We then tried to identify Th17 cells, IL-17(+)Th17 cells, and IFNγ (+)Th17 cells in the peripheral blood of early-onset RA patients using the standardized method of the Human Immunology Project. Our findings validated the method and the expression of CD161. The ratio of IFNγ (+)Th17 cells in memory T cells was inversely correlated to the titers of anti-CCP antibodies in the early-onset RA patients. These findings suggest that Th17 cells play important roles in the early phase of RA and that anti-IL-17 antibodies should be administered to patients with early phase RA, especially those with high titers of CCP antibodies.

Dual orientation of the outer membrane lipoprotein P6 of nontypeable haemophilus influenzae.

PubMed

Michel, Lea Vacca; Snyder, Joy; Schmidt, Rachel; Milillo, Jennifer; Grimaldi, Kyle; Kalmeta, Breanna; Khan, M Nadeem; Sharma, Sharad; Wright, Leslie Kate; Pichichero, Michael E

2013-07-01

The majority of outer membrane (OM) lipoproteins in Gram-negative bacteria are tethered to the membrane via an attached lipid moiety and oriented facing in toward the periplasmic space; a few lipoproteins have been shown to be surface exposed. The outer membrane lipoprotein P6 from the Gram-negative pathogenic bacterium nontypeable Haemophilus influenzae (NTHi) is surface exposed and a leading vaccine candidate for prevention of NTHi infections. However, we recently found that P6 is not a transmembrane protein as previously thought (L. V. Michel, B. Kalmeta, M. McCreary, J. Snyder, P. Craig, M. E. Pichichero, Vaccine 29:1624-1627, 2011). Here we pursued studies to show that P6 has a dual orientation, existing infrequently as surface exposed and predominantly as internally oriented toward the periplasmic space. Flow cytometry using three monoclonal antibodies with specificity for P6 showed surface staining of whole NTHi cells. Confocal microscopy imaging confirmed that antibodies targeted surface-exposed P6 of intact NTHi cells and not internal P6 in membrane-compromised or dead cells. Western blots of two wild-type NTHi strains and a mutant NTHi strain that does not express P6 showed that P6 antibodies do not detect a promiscuous epitope on NTHi. Depletion of targets to nonlipidated P6 significantly decreased bactericidal activity of human serum. Protease digestion of surface-exposed P6 demonstrated that P6 is predominantly internally localized in a manner similar to its homologue Pal in Escherichia coli. We conclude that P6 of NTHi is likely inserted into the OM in two distinct orientations, with the predominant orientation facing in toward the periplasm.

Verification of immune response optimality through cybernetic modeling.

PubMed

Batt, B C; Kompala, D S

1990-02-09

An immune response cascade that is T cell independent begins with the stimulation of virgin lymphocytes by antigen to differentiate into large lymphocytes. These immune cells can either replicate themselves or differentiate into plasma cells or memory cells. Plasma cells produce antibody at a specific rate up to two orders of magnitude greater than large lymphocytes. However, plasma cells have short life-spans and cannot replicate. Memory cells produce only surface antibody, but in the event of a subsequent infection by the same antigen, memory cells revert rapidly to large lymphocytes. Immunologic memory is maintained throughout the organism's lifetime. Many immunologists believe that the optimal response strategy calls for large lymphocytes to replicate first, then differentiate into plasma cells and when the antigen has been nearly eliminated, they form memory cells. A mathematical model incorporating the concept of cybernetics has been developed to study the optimality of the immune response. Derived from the matching law of microeconomics, cybernetic variables control the allocation of large lymphocytes to maximize the instantaneous antibody production rate at any time during the response in order to most efficiently inactivate the antigen. A mouse is selected as the model organism and bacteria as the replicating antigen. In addition to verifying the optimal switching strategy, results showing how the immune response is affected by antigen growth rate, initial antigen concentration, and the number of antibodies required to eliminate an antigen are included.

Reduced Potency and Incomplete Neutralization of Broadly Neutralizing Antibodies against Cell-to-Cell Transmission of HIV-1 with Transmitted Founder Envs.

PubMed

Li, Hongru; Zony, Chati; Chen, Ping; Chen, Benjamin K

2017-05-01

Broadly neutralizing antibodies (bNAbs) have been isolated from HIV-1 patients and can potently block infection of a wide spectrum of HIV-1 subtypes. These antibodies define common epitopes shared by many viral isolates. While bNAbs potently antagonize infection with cell-free virus, inhibition of HIV-1 transmission from infected to uninfected CD4 + T cells through virological synapses (VS) has been found to require greater amounts of antibody. In this study, we examined two well-studied molecular clones and two transmitted/founder (T/F) clones for their sensitivities to a panel of bNAbs in cell-free and cell-to-cell infection assays. We observed resistance of cell-to-cell transmission to antibody neutralization that was reflected not only by reductions of antibody potency but also by decreases in maximum neutralization capacity relative to the levels seen with cell-free infections. BNAbs targeting different epitopes exhibited incomplete neutralization against cell-associated virus with T/F Envs, which was not observed with the cell-free form of the same virus. We further identified the membrane-proximal internal tyrosine-based sorting motif as a determinant that can affect the incomplete neutralization of these T/F clones in cell-to-cell infection. These findings indicate that the signal that affects surface expression and/or internalization of Env from the plasma membrane can modulate the presentation of neutralizing epitopes on infected cells. These results highlight that a fraction of virus can escape from high concentrations of antibody through cell-to-cell infection while remaining sensitive to neutralization in cell-free infection. The ability to fully inhibit cell-to-cell transmission may represent an important consideration in the development of antibodies for treatment or prophylaxis. IMPORTANCE In recent years, isolation of new-generation HIV-1 bNAbs has invigorated HIV vaccine research. These bNAbs display remarkable potency and breadth of coverage against cell-free virus; however, they exhibit a diminished ability to block HIV-1 cell-to-cell transmission. The mechanism(s) by which HIV-1 resists neutralization when transmitting through VS remains uncertain. We examined a panel of bNAbs for their ability to neutralize HIV-1 T/F viruses in cell-to-cell infection assays. We found that some antibodies exhibit not only reduced potency but also decreased maximum neutralization capacity or in vitro efficacy against cell-to-cell infection of HIV-1 with T/F Envs compared to cell-free infection of the same virus. We further identified the membrane-proximal internal tyrosine-based sorting motif YXXL as a determinant that can affect the incomplete neutralization phenotype of these T/F clones. When the maximum neutralization capacity falls short of 100%, this can have a major impact on the ability of antibodies to halt viral replication. Copyright © 2017 American Society for Microbiology.

Different Regions of the Malaria Merozoite Surface Protein 1 of Plasmodium chabaudi Elicit Distinct T-Cell and Antibody Isotype Responses

PubMed Central

Quin, Stuart J.; Langhorne, Jean

2001-01-01

In this study we have investigated the antibody and CD4 T-cell responses to the well-characterized malaria vaccine candidate MSP-1 during the course of a primary Plasmodium chabaudi chabaudi (AS) infection. Specific antibody responses can be detected within the first week of infection, and CD4 T cells can be detected after 3 weeks of infection. The magnitude of the CD4 T-cell response elicited during a primary infection depended upon the region of MSP-1. In general, the highest precursor frequencies were obtained when a recombinant MSP-1 fragment corresponding to amino acids 900 to 1507 was used as the antigen in vitro. By contrast, proliferative and cytokine responses against amino acids 1508 to 1766 containing the C-terminal 21-kDa region of the molecule were low. The characteristic interleukin 4 (IL-4) switch that occurs in the CD4 T-cell population after an acute blood stage P. c. chabaudi infection was only consistently observed in the response to the amino acid 900 to 1507 MSP1 fragment. A lower frequency of IL-4-producing cells was seen in response to other regions. Although the magnitudes of the immunoglobulin G antibody responses to the different regions of MSP-1 were similar, the isotype composition of each response was distinct, and there was no obvious relationship with the type of T helper cells generated. Interestingly, a relatively high antibody response to the C-terminal region of MSP-1 was observed, suggesting that T-cell epitopes outside of this region may provide the necessary cognate help for specific antibody production. PMID:11254580

Antibodies against multiple merozoite surface antigens of the human malaria parasite Plasmodium falciparum inhibit parasite maturation and red blood cell invasion.

PubMed

Woehlbier, Ute; Epp, Christian; Hackett, Fiona; Blackman, Michael J; Bujard, Hermann

2010-03-18

Plasmodium falciparum merozoites expose at their surface a large protein complex, which is composed of fragments of merozoite surface protein 1 (MSP-1; called MSP-183, MSP-130, MSP-138, and MSP-142) plus associated processing products of MSP-6 and MSP-7. During erythrocyte invasion this complex, as well as an integral membrane protein called apical membrane antigen-1 (AMA-1), is shed from the parasite surface following specific proteolysis. Components of the MSP-1/6/7 complex and AMA-1 are presently under development as malaria vaccines. The specificities and effects of antibodies directed against MSP-1, MSP-6, MSP-7 on the growth of blood stage parasites were studied using ELISA and the pLDH-assay. To understand the mode of action of these antibodies, their effects on processing of MSP-1 and AMA-1 on the surface of merozoites were investigated. Antibodies targeting epitopes located throughout the MSP-1/6/7 complex interfere with shedding of MSP-1, and as a consequence prevent erythrocyte invasion. Antibodies targeting the MSP-1/6/7 complex have no effect on the processing and shedding of AMA-1 and, similarly, antibodies blocking the shedding of AMA-1 do not affect cleavage of MSP-1, suggesting completely independent functions of these proteins during invasion. Furthermore, some epitopes, although eliciting highly inhibitory antibodies, are only poorly recognized by the immune system when presented in the structural context of the intact antigen. The findings reported provide further support for the development of vaccines based on MSP-1/6/7 and AMA-1, which would possibly include a combination of these antigens.

AFM, CLSM and EIS characterization of the immobilization of antibodies on indium-tin oxide electrode and their capture of Legionella pneumophila.

PubMed

Souiri, Mina; Blel, Nesrine; Sboui, Dejla; Mhamdi, Lotfi; Epalle, Thibaut; Mzoughi, Ridha; Riffard, Serge; Othmane, Ali

2014-01-01

The microscopic surface molecular structures and properties of monoclonal anti-Legionella pneumophila antibodies on an indium-tin oxide (ITO) electrode surface were studied to elaborate an electrochemical immunosensor for Legionella pneumophila detection. A monoclonal anti-Legionella pneumophila antibody (MAb) has been immobilized onto an ITO electrode via covalent chemical bonds between antibodies amino-group and the ring of (3-Glycidoxypropyl) trimethoxysilane (GPTMS). The functionalization of the immunosensor was characterized by atomic force microscopy (AFM), water contact angle measurement, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in the presence of [Fe(CN)₆](3-/4-) as a redox probe. Specific binding of Legionella pneumophila sgp 1 cells onto the antibody-modified ITO electrode was shown by confocal laser scanning microscopy (CLSM) imaging and EIS. AFM images evidenced the dense and relatively homogeneous morphology on the ITO surface. The formation of the complex epoxysilane-antibodies acting as barriers for the electron transfer between the electrode surface and the redox species in the solution induced a significant increase in the charge transfer resistance (Rct) compared to all the electric elements. A linear relationship between the change in charge transfer resistance (ΔRct=Rct after immunoreactions - Rct control) and the logarithmic concentration value of L. pneumophila was observed in the range of 5 × 10(1)-5 × 10(4) CFU mL(-1) with a limit of detection 5 × 10(1)CFU mL(-1). The present study has demonstrated the successful deposition of an anti-L. pneumophila antibodies on an indium-tin oxide surface, opening its subsequent use as immuno-captor for the specific detection of L. pneumophila in environmental samples. © 2013 Elsevier B.V. All rights reserved.

HIV blocking antibodies following immunisation with chimaeric peptides coding a short N-terminal sequence of the CCR5 receptor.

PubMed

Chain, Benjamin M; Noursadeghi, Mahdad; Gardener, Michelle; Tsang, Jhen; Wright, Edward

2008-10-23

The chemokine receptor CCR5 is required for cellular entry by many strains of HIV, and provides a potential target for molecules, including antibodies, designed to block HIV transmission. This study investigates a novel approach to stimulate antibodies to CCR5. Rabbits were immunised with chimaeric peptides which encode a short fragment of the N-terminal sequence of CCR5, as well as an unrelated T cell epitope from Tetanus toxoid. Immunisation with these chimaeric peptides generates a strong antibody response which is highly focused on the N-terminal CCR5 sequence. The antibody to the chimaeric peptide containing an N-terminal methionine also recognises the full length CCR5 receptor on the cell surface, albeit at higher concentrations. Further comparison of binding to intact CCR5 with binding to CCR5 peptide suggest that the receptor specific antibody generated represents a very small fragment of the total anti-peptide antibody. These findings are consistent with the hypothesis that the N-terminal peptide in the context of the intact receptor has a different structure to that of the synthetic peptide. Finally, the antibody was able to block HIV infection of macrophages in vitro. Thus results of this study suggest that N-terminal fragments of CCR5 may provide potential immunogens with which to generate blocking antibodies to this receptor, while avoiding the dangers of including T cell auto-epitopes.

HIV blocking antibodies following immunisation with chimaeric peptides coding a short N-terminal sequence of the CCR5 receptor

PubMed Central

Chain, Benjamin M.; Noursadeghi, Mahdad; Gardener, Michelle; Tsang, Jhen; Wright, Edward

2008-01-01

The chemokine receptor CCR5 is required for cellular entry by many strains of HIV, and provides a potential target for molecules, including antibodies, designed to block HIV transmission. This study investigates a novel approach to stimulate antibodies to CCR5. Rabbits were immunised with chimaeric peptides which encode a short fragment of the N-terminal sequence of CCR5, as well as an unrelated T cell epitope from Tetanus toxoid. Immunisation with these chimaeric peptides generates a strong antibody response which is highly focused on the N-terminal CCR5 sequence. The antibody to the chimaeric peptide containing an N-terminal methionine also recognises the full length CCR5 receptor on the cell surface, albeit at higher concentrations. Further comparison of binding to intact CCR5 with binding to CCR5 peptide suggest that the receptor specific antibody generated represents a very small fragment of the total anti-peptide antibody. These findings are consistent with the hypothesis that the N-terminal peptide in the context of the intact receptor has a different structure to that of the synthetic peptide. Finally, the antibody was able to block HIV infection of macrophages in vitro. Thus results of this study suggest that N-terminal fragments of CCR5 may provide potential immunogens with which to generate blocking antibodies to this receptor, while avoiding the dangers of including T cell auto-epitopes. PMID:18765264

The Bordetella Adenylate Cyclase Repeat-in-Toxin (RTX) Domain Is Immunodominant and Elicits Neutralizing Antibodies*

PubMed Central

Wang, Xianzhe; Maynard, Jennifer A.

2015-01-01

The adenylate cyclase toxin (ACT) is a multifunctional virulence factor secreted by Bordetella species. Upon interaction of its C-terminal hemolysin moiety with the cell surface receptor αMβ2 integrin, the N-terminal cyclase domain translocates into the host cell cytosol where it rapidly generates supraphysiological cAMP concentrations, which inhibit host cell anti-bacterial activities. Although ACT has been shown to induce protective immunity in mice, it is not included in any current acellular pertussis vaccines due to protein stability issues and a poor understanding of its role as a protective antigen. Here, we aimed to determine whether any single domain could recapitulate the antibody responses induced by the holo-toxin and to characterize the dominant neutralizing antibody response. We first immunized mice with ACT and screened antibody phage display libraries for binding to purified ACT. The vast majority of unique antibodies identified bound the C-terminal repeat-in-toxin (RTX) domain. Representative antibodies binding two nonoverlapping, neutralizing epitopes in the RTX domain prevented ACT association with J774A.1 macrophages and soluble αMβ2 integrin, suggesting that these antibodies inhibit the ACT-receptor interaction. Sera from mice immunized with the RTX domain showed similar neutralizing activity as ACT-immunized mice, indicating that this domain induced an antibody response similar to that induced by ACT. These data demonstrate that RTX can elicit neutralizing antibodies and suggest it may present an alternative to ACT. PMID:25505186

Isolation of HIV-1-Neutralizing Mucosal Monoclonal Antibodies from Human Colostrum

PubMed Central

Friedman, James; Alam, S. Munir; Shen, Xiaoying; Xia, Shi-Mao; Stewart, Shelley; Anasti, Kara; Pollara, Justin; Fouda, Genevieve G.; Yang, Guang; Kelsoe, Garnett; Ferrari, Guido; Tomaras, Georgia D.; Haynes, Barton F.; Liao, Hua-Xin

2012-01-01

Background Generation of potent anti-HIV antibody responses in mucosal compartments is a potential requirement of a transmission-blocking HIV vaccine. HIV-specific, functional antibody responses are present in breast milk, and these mucosal antibody responses may play a role in protection of the majority of HIV-exposed, breastfeeding infants. Therefore, characterization of HIV-specific antibodies produced by B cells in milk could guide the development of vaccines that elicit protective mucosal antibody responses. Methods We isolated B cells from colostrum of an HIV-infected lactating woman with a detectable neutralization response in milk and recombinantly produced and characterized the resulting HIV-1 Envelope (Env)-specific monoclonal antibodies (mAbs). Results The identified HIV-1 Env-specific colostrum mAbs, CH07 and CH08, represent two of the first mucosally-derived anti-HIV antibodies yet to be reported. Colostrum mAb CH07 is a highly-autoreactive, weakly-neutralizing gp140-specific mAb that binds to linear epitopes in the gp120 C5 region and gp41 fusion domain. In contrast, colostrum mAb CH08 is a nonpolyreactive CD4-inducible (CD4i) gp120-specific mAb with moderate breadth of neutralization. Conclusions These novel HIV-neutralizing mAbs isolated from a mucosal compartment provide insight into the ability of mucosal B cell populations to produce functional anti-HIV antibodies that may contribute to protection against virus acquisition at mucosal surfaces. PMID:22624058

Monoclonal Antibody Binding to a Surface-Exposed Epitope on Cowdria ruminantium That Is Conserved among Eight Strains

PubMed Central

Shompole, Sankale; Rurangirwa, Fred R.; Wambugu, Anderson; Sitienei, John; Mwangi, Duncan M.; Musoke, Anthony J.; Mahan, Suman; Wells, Clive W.; McGuire, Travis C.

2000-01-01

Monoclonal antibodies (MAb) binding to Cowdria ruminantium elementary bodies (EB) were identified by enzyme-linked immunosorbent assay, and surface binding of one MAb (446.15) to intact EB was determined by immunofluorescence, immunogold labeling, and transmission electron microscopy. MAb 446.15 bound an antigen of approximately 43 kDa in immunoblots of eight geographically distinct strains. The MAb did not react with Ehrlichia canis antigens or uninfected bovine endothelial cell lysate and may be useful in diagnostic assays and vaccine development. PMID:11063511

Combined use of anti-ErbB monoclonal antibodies and erlotinib enhances antibody-dependent cellular cytotoxicity of wild-type erlotinib-sensitive NSCLC cell lines

PubMed Central

2012-01-01

Background The epidermal growth factor receptor (EGFR) is an established target for anti-cancer treatment in different tumour types. Two different strategies have been explored to inhibit this pivotal molecule in epithelial cancer development: small molecules TKIs and monoclonal antibodies. ErbB/HER-targeting by monoclonal antibodies such as cetuximab and trastuzumab or tyrosine-kinase inhibitors as gefitinib or erlotinib has been proven effective in the treatment of advanced NSCLC. Results In this study we explored the potential of combining either erlotinib with cetuximab or trastuzumab to improve the efficacy of EGFR targeted therapy in EGFR wild-type NSCLC cell lines. Erlotinib treatment was observed to increase EGFR and/or HER2 expression at the plasma membrane level only in NSCLC cell lines sensitive to the drug inducing protein stabilization. The combined treatment had marginal effect on cell proliferation but markedly increased antibody-dependent, NK mediated, cytotoxicity in vitro. Moreover, in the Calu-3 xenograft model, the combination significantly inhibited tumour growth when compared with erlotinib and cetuximab alone. Conclusion Our results indicate that erlotinib increases surface expression of EGFR and/or HER2 only in EGFR-TKI sensitive NSCLC cell lines and, in turns, leads to increased susceptibility to ADCC both in vitro and in a xenograft models. The combination of erlotinib with monoclonal antibodies represents a potential strategy to improve the treatment of wild-type EGFR NSCLC patients sensitive to erlotinib. PMID:23234355

Exocytosis of vacuolar apical compartment (VAC): a cell-cell contact controlled mechanism for the establishment of the apical plasma membrane domain in epithelial cells

PubMed Central

1988-01-01

The vacuolar apical compartment (VAC) is an organelle found in Madin- Darby canine kidney (MDCK) cells with incomplete intercellular contacts by incubation in 5 microM Ca++ and in cells without contacts (single cells in subconfluent culture); characteristically, it displays apical biochemical markers and microvilli and excludes basolateral markers (Vega-Salas, D. E., P. J. I. Salas, and E. Rodriguez-Boulan. 1987. J. Cell Biol. 104:1249-1259). The apical surface of cells kept under these culture conditions is immature, with reduced numbers of microvilli and decreased levels of an apical biochemical marker (184 kD), which is, however, still highly polarized (Vega-Salas, D. E., P. J. I. Salas, D. Gundersen, and E. Rodriguez-Boulan. 1987. J. Cell Biol. 104:905-916). We describe here the morphological stages of VAC exocytosis which ultimately lead to the establishment of a differentiated apical domain. Addition of 1.8 mM Ca++ to monolayers developed in 5 microM Ca++ causes the rapid (20-40 min) fusion of VACs with the plasma membrane and their accessibility to external antibodies, as demonstrated by immunofluorescence, immunoperoxidase EM, and RIA with antibodies against the 184-kD apical plasma membrane marker. Exocytosis occurs towards areas of cell-cell contact in the developing lateral surface where they form intercellular pockets; fusion images are always observed immediately adjacent to the incomplete junctional bands detected by the ZO-1 antibody (Stevenson, B. R., J. D. Siliciano, M. S. Mooseker, and D. A. Goodenough. 1986. J. Cell Biol. 103:755-766). Blocks of newly incorporated VAC microvilli and 184-kD protein progressively move from intercellular ("primitive" lateral) spaces towards the microvilli-poor free cell surface. The definitive lateral domain is sealed behind these blocks by the growing tight junctional fence. These results demonstrate a fundamental role of cell-cell contact-mediated VAC exocytosis in the establishment of epithelial surface polarity. Because isolated stages (intercellular pockets) of the stereotyped sequence of events triggered by the establishment of intercellular contacts in MDCK cells have been reported during normal differentiation of intestine epithelium (Colony, P. C., and M. R. Neutra. 1983. Dev. Biol. 97:349-363), we speculate that the mechanism we describe here plays an important role in the establishment of epithelial cell polarity in vivo. PMID:3053735

The antiangiogenic activity of cleaved high molecular weight kininogen is mediated through binding to endothelial cell tropomyosin

PubMed Central

Zhang, Jing-Chuan; Doñate, Fernando; Qi, Xiaoping; Ziats, Nicholas P.; Juarez, Jose C.; Mazar, Andrew P.; Pang, Yuan-Ping; McCrae, Keith R.

2002-01-01

Conformationally altered proteins and protein fragments derived from the extracellular matrix and hemostatic system may function as naturally occurring angiogenesis inhibitors. One example of such a protein is cleaved high molecular weight kininogen (HKa). HKa inhibits angiogenesis by inducing apoptosis of proliferating endothelial cells, effects mediated largely by HKa domain 5. However, the mechanisms underlying the antiangiogenic activity of HKa have not been characterized, and its binding site on proliferating endothelial cells has not been defined. Here, we report that the induction of endothelial cell apoptosis by HKa, as well as the antiangiogenic activity of HKa in the chick chorioallantoic membrane, was inhibited completely by antitropomyosin monoclonal antibody TM-311. TM-311 also blocked the high-affinity Zn2+-dependent binding of HKa to both purified tropomyosin and proliferating endothelial cells. Confocal microscopic analysis of endothelial cells stained with monoclonal antibody TM-311, as well as biotin labeling of cell surface proteins on intact endothelial cells, revealed that tropomyosin exposure was enhanced on the surface of proliferating cells. These studies demonstrate that the antiangiogenic effects of HKa depend on high-affinity binding to endothelial cell tropomyosin. PMID:12196635

Co-receptor Binding Site Antibodies Enable CD4-Mimetics to Expose Conserved Anti-cluster A ADCC Epitopes on HIV-1 Envelope Glycoproteins.

PubMed

Richard, Jonathan; Pacheco, Beatriz; Gohain, Neelakshi; Veillette, Maxime; Ding, Shilei; Alsahafi, Nirmin; Tolbert, William D; Prévost, Jérémie; Chapleau, Jean-Philippe; Coutu, Mathieu; Jia, Manxue; Brassard, Nathalie; Park, Jongwoo; Courter, Joel R; Melillo, Bruno; Martin, Loïc; Tremblay, Cécile; Hahn, Beatrice H; Kaufmann, Daniel E; Wu, Xueling; Smith, Amos B; Sodroski, Joseph; Pazgier, Marzena; Finzi, Andrés

2016-10-01

Human immunodeficiency virus type 1 (HIV-1) has evolved a sophisticated strategy to conceal conserved epitopes of its envelope glycoproteins (Env) recognized by antibody-dependent cellular cytotoxicity (ADCC)-mediating antibodies. These antibodies, which are present in the sera of most HIV-1-infected individuals, preferentially recognize Env in its CD4-bound conformation. Accordingly, recent studies showed that small CD4-mimetics (CD4mc) able to "push" Env into this conformation sensitize HIV-1-infected cells to ADCC mediated by HIV+ sera. Here we test whether CD4mc also expose epitopes recognized by anti-cluster A monoclonal antibodies such as A32, thought to be responsible for the majority of ADCC activity present in HIV+ sera and linked to decreased HIV-1 transmission in the RV144 trial. We made the surprising observation that CD4mc are unable to enhance recognition of HIV-1-infected cells by this family of antibodies in the absence of antibodies such as 17b, which binds a highly conserved CD4-induced epitope overlapping the co-receptor binding site (CoRBS). Our results indicate that CD4mc initially open the trimeric Env enough to allow the binding of CoRBS antibodies but not anti-cluster A antibodies. CoRBS antibody binding further opens the trimeric Env, allowing anti-cluster A antibody interaction and sensitization of infected cells to ADCC. Therefore, ADCC responses mediated by cluster A antibodies in HIV-positive sera involve a sequential opening of the Env trimer on the surface of HIV-1-infected cells. The understanding of the conformational changes required to expose these vulnerable Env epitopes might be important in the design of new strategies aimed at fighting HIV-1. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Ratio of Circulating IFNγ + “Th17 Cells” in Memory Th Cells Is Inversely Correlated with the Titer of Anti-CCP Antibodies in Early-Onset Rheumatoid Arthritis Patients Based on Flow Cytometry Methods of the Human Immunology Project

PubMed Central

Kotake, Shigeru; Nanke, Yuki; Yago, Toru; Kawamoto, Manabu; Kobashigawa, Tsuyoshi; Yamanaka, Hisashi

2016-01-01

Rheumatoid arthritis (RA) is a systemic autoimmune disease with chronic joint inflammation characterized by activated T cells. IL-17 and Th17 cells play important roles in the pathogenesis of RA. Recently, plasticity in helper T cells has been demonstrated; Th17 cells can convert to Th1 cells. However, it remains to be elucidated whether this conversion occurs in the early phase of RA. Here, we validated the methods of the Human Immunology Project using only the cell-surface marker through measuring the actual expression of IL-17 and IFNγ. We also evaluated the expression of CD161 in human Th17 cells. We then tried to identify Th17 cells, IL-17+Th17 cells, and IFNγ +Th17 cells in the peripheral blood of early-onset RA patients using the standardized method of the Human Immunology Project. Our findings validated the method and the expression of CD161. The ratio of IFNγ +Th17 cells in memory T cells was inversely correlated to the titers of anti-CCP antibodies in the early-onset RA patients. These findings suggest that Th17 cells play important roles in the early phase of RA and that anti-IL-17 antibodies should be administered to patients with early phase RA, especially those with high titers of CCP antibodies. PMID:27294146

Phenotypic and functional characterization of T cells from patients with myasthenia gravis.

PubMed Central

Mokhtarian, F; Pino, M; Ofosu-Appiah, W; Grob, D

1990-01-01

A study of cell surface phenotypes of PBL of myasthenia gravis (MG) patients showed that their T cells had a significantly higher percentage of 4B4+ T cells (the helper/inducer subset) than age- and sex-matched controls. The PBL of MG patients proliferated significantly higher than those of normal subjects (NS) in response to the purified alpha chain of the acetylcholine receptor (AChR). Anti-AChR antibody was present in sera of 88% of MG and none of the NS. The PBL B cells from MG only, when cultured with autologous T cells and stimulated with either pokeweed mitogen (69%), or AChR-alpha chain (38%), secreted antibody to AChR-alpha chain, whereas T and B cells alone secreted no antibody. T cells from PBL of MG patients were more readily cloned than T cells of NS, by limiting dilution, in the presence of recombinant IL-2 and in the absence of AChR-alpha chain. About 50% of T cell clones from MG patients, compared to none from NS, proliferated to AChR-alpha chain. This response was HLA-DR restricted. MG T cell clones did not display significant cytotoxic activity, as compared to control T cell clones. Our results indicate that in MG, 4B4+ regulatory T cells play their role in the pathogenesis of MG, not by cytotoxicity, but more likely by their ability to stimulate specific antibody production by B cells. Images PMID:1979338

Cross-specificity of protective human antibodies against Klebsiella pneumoniae LPS O-antigen.

PubMed

Rollenske, Tim; Szijarto, Valeria; Lukasiewicz, Jolanta; Guachalla, Luis M; Stojkovic, Katarina; Hartl, Katharina; Stulik, Lukas; Kocher, Simone; Lasitschka, Felix; Al-Saeedi, Mohammed; Schröder-Braunstein, Jutta; von Frankenberg, Moritz; Gaebelein, Gereon; Hoffmann, Peter; Klein, Sabrina; Heeg, Klaus; Nagy, Eszter; Nagy, Gabor; Wardemann, Hedda

2018-06-01

Humoral immune responses to microbial polysaccharide surface antigens can prevent bacterial infection but are typically strain specific and fail to mediate broad protection against different serotypes. Here we describe a panel of affinity-matured monoclonal human antibodies from peripheral blood immunoglobulin M-positive (IgM + ) and IgA + memory B cells and clonally related intestinal plasmablasts, directed against the lipopolysaccharide (LPS) O-antigen of Klebsiella pneumoniae, an opportunistic pathogen and major cause of antibiotic-resistant nosocomial infections. The antibodies showed distinct patterns of in vivo cross-specificity and protection against different clinically relevant K. pneumoniae serotypes. However, cross-specificity was not limited to K. pneumoniae, as K. pneumoniae-specific antibodies recognized diverse intestinal microbes and neutralized not only K. pneumoniae LPS but also non-K. pneumoniae LPS. Our data suggest that the recognition of minimal glycan epitopes abundantly expressed on microbial surfaces might serve as an efficient humoral immunological mechanism to control invading pathogens and the large diversity of the human microbiota with a limited set of cross-specific antibodies.

A Heterodimer of a VHH (Variable Domains of Camelid Heavy Chain-only) Antibody That Inhibits Anthrax Toxin Cell Binding Linked to a VHH Antibody That Blocks Oligomer Formation Is Highly Protective in an Anthrax Spore Challenge Model*

PubMed Central

Moayeri, Mahtab; Leysath, Clinton E.; Tremblay, Jacqueline M.; Vrentas, Catherine; Crown, Devorah; Leppla, Stephen H.; Shoemaker, Charles B.

2015-01-01

Anthrax disease is caused by a toxin consisting of protective antigen (PA), lethal factor, and edema factor. Antibodies against PA have been shown to be protective against the disease. Variable domains of camelid heavy chain-only antibodies (VHHs) with affinity for PA were obtained from immunized alpacas and screened for anthrax neutralizing activity in macrophage toxicity assays. Two classes of neutralizing VHHs were identified recognizing distinct, non-overlapping epitopes. One class recognizes domain 4 of PA at a well characterized neutralizing site through which PA binds to its cellular receptor. A second neutralizing VHH (JKH-C7) recognizes a novel epitope. This antibody inhibits conversion of the PA oligomer from “pre-pore” to its SDS and heat-resistant “pore” conformation while not preventing cleavage of full-length 83-kDa PA (PA83) by cell surface proteases to its oligomer-competent 63-kDa form (PA63). The antibody prevents endocytosis of the cell surface-generated PA63 subunit but not preformed PA63 oligomers formed in solution. JKH-C7 and the receptor-blocking VHH class (JIK-B8) were expressed as a heterodimeric VHH-based neutralizing agent (VNA2-PA). This VNA displayed improved neutralizing potency in cell assays and protected mice from anthrax toxin challenge with much better efficacy than the separate component VHHs. The VNA protected virtually all mice when separately administered at a 1:1 ratio to toxin and protected mice against Bacillus anthracis spore infection. Thus, our studies show the potential of VNAs as anthrax therapeutics. Due to their simple and stable nature, VNAs should be amenable to genetic delivery or administration via respiratory routes. PMID:25564615

A heterodimer of a VHH (variable domains of camelid heavy chain-only) antibody that inhibits anthrax toxin cell binding linked to a VHH antibody that blocks oligomer formation is highly protective in an anthrax spore challenge model.

PubMed

Moayeri, Mahtab; Leysath, Clinton E; Tremblay, Jacqueline M; Vrentas, Catherine; Crown, Devorah; Leppla, Stephen H; Shoemaker, Charles B

2015-03-06

Anthrax disease is caused by a toxin consisting of protective antigen (PA), lethal factor, and edema factor. Antibodies against PA have been shown to be protective against the disease. Variable domains of camelid heavy chain-only antibodies (VHHs) with affinity for PA were obtained from immunized alpacas and screened for anthrax neutralizing activity in macrophage toxicity assays. Two classes of neutralizing VHHs were identified recognizing distinct, non-overlapping epitopes. One class recognizes domain 4 of PA at a well characterized neutralizing site through which PA binds to its cellular receptor. A second neutralizing VHH (JKH-C7) recognizes a novel epitope. This antibody inhibits conversion of the PA oligomer from "pre-pore" to its SDS and heat-resistant "pore" conformation while not preventing cleavage of full-length 83-kDa PA (PA83) by cell surface proteases to its oligomer-competent 63-kDa form (PA63). The antibody prevents endocytosis of the cell surface-generated PA63 subunit but not preformed PA63 oligomers formed in solution. JKH-C7 and the receptor-blocking VHH class (JIK-B8) were expressed as a heterodimeric VHH-based neutralizing agent (VNA2-PA). This VNA displayed improved neutralizing potency in cell assays and protected mice from anthrax toxin challenge with much better efficacy than the separate component VHHs. The VNA protected virtually all mice when separately administered at a 1:1 ratio to toxin and protected mice against Bacillus anthracis spore infection. Thus, our studies show the potential of VNAs as anthrax therapeutics. Due to their simple and stable nature, VNAs should be amenable to genetic delivery or administration via respiratory routes. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

[Monoclonal antibodies in diagnosis of acute leukemias].

PubMed

Krawczyńska, A; Robak, T

1996-01-01

Immunophenotyping has become an essential component for the study of acute myeloblastic (AML) and lymphoblastic (ALL) leukaemias. The recent development of highly specific monoclonal antibodies (Mc Ab) to differentiation antigens (CD) of haematopoetic cells have made it readily available to clinical laboratories in most major hospitals. Immunophenotyping complements standard morphology by providing information on lineage, stage of differentiation and clonality. In addition some of the flow cytometry findings have independent prognostic significance. Monoclonal antibodies useful in defining lineage (B-cell versus T-cell) and stages of differentiation of ALL. It can be also used in identifying characteristic feature of AML and aiding in lineage determination in acute leukaemias that are morphologically undifferentiated. Surface immunophenotyping is especially helpful for recognizing mixed lineage acute leukaemia and diagnosing certain rare entities such as erythroleukaemia (M6), acute megakaryocytic leukaemia (M7) and minimally differentiation acute myeloid leukaemia.

Renewable Surface Fluorescence Sandwich Immunoassay Biosensor for Rapid Sensitive Botulinum Toxin Detection in an Automated Fluidic Format

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grate, Jay W.; Warner, Marvin G.; Ozanich, Richard M.

2009-03-05

A renewable surface biosensor for rapid detection of botulinum toxin is described based on fluidic automation of a fluorescence sandwich immunoassay, using a recombinant fragment of the toxin heavy chain as a structurally valid simulant. Monoclonal antibodies AR4 and RAZ1 bind to separate epitopes of both this fragment and the holotoxin. The AR4 antibody was covalently bound to Sepharose beads and used as the capture antibody. A rotating rod flow cell was used to capture these beads delivered as a suspension by the sequential injection flow system, creating a 3.6 microliter column. After perfusing the bead column with sample andmore » washing away the matrix, the column was perfused with Alexa 647 dye-labeled RAZ1 antibody as the reporter. Optical fibers coupled to the rotating rod flow cell at a 90 degree angle to one another delivered excitation light from a HeNe laser and collected fluorescent emission light for detection. After each measurement, the used sepharose beads are released and replaced with fresh beads. In a rapid screening approach to sample analysis, the toxin simulant was detected to concentrations of 10 pM in less than 20 minutes.« less

Immunological relationships between glucosyltransferases from Streptococcus mutans serotypes.

PubMed

Kuramitsu, H; Ingersoll, L

1976-09-01

Partially purified glycosyltransferase enzymes for Streptococcus mutans GS-5 (serotype c) have been utilized to prepare antibodies directed against the soluble glucan-synthesizing activity, GTF-B, and the insoluble-soluble glucan synthetic activity, GTF-A. Anti-GTF-A inhibited insoluble glucan formation catalyzed by the extracellular enzymes from strains GS-5 and FA-1 (serotype b) to a much greater extent than that of strains HS-6 (serotype a) or OMZ-176 (serotype d). This antibody fraction also inhibited both the cell-associated glucosyltransferase activities as well as the sucrose-mediated adherence of cells to glass surfaces by strains GS-5 and FA-1 but not that of strains HS-6 and OMZ-176. Anti-GTF-B inhibited soluble glucan formation catalyzed by the extracellular enzymes of strains GS-5 but not that of strain HS-6, FA-1, or OMZ-176. However, this antibody fraction did not strongly inhibit either the cell-associated glycosyltransferase activity or cellular adherence of any of the four strains. These results with body antibody fractions were also correlated with the ability of the antibodies to agglutinate the cells and form precipitin bands after immunodiffusion with the extracellular enzymes. Antibody prepared against the homogeneous soluble glucan-synthesizing enzyme demonstrated similar effects to the anti-GTF-B fraction. These results are discussed in terms of the antigenic relationships existing between the glucosyltransferases from different serotypes of S. mutans.

Trichinella spiralis: killing of newborn larvae by lung cells.

PubMed

Falduto, Guido H; Vila, Cecilia C; Saracino, María P; Calcagno, Marcela A; Venturiello, Stella M

2015-02-01

The migratory stage of Trichinella spiralis, the newborn larva (NBL), travels along the pulmonary microvascular system on its way to the skeletal muscle cells. The present work studies the capability of lung cells to kill NBL. For this purpose, in vitro cytotoxicity assays were performed using NBL, lung cell suspensions from Wistar rats, rat anti-NBL surface sera, and fresh serum as complement source. The cytotoxic activity of lung cells from rats infected on day 6 p.i. was compared with that from noninfected rats. Two and 20 h-old NBL (NBL2 and NBL20) were used as they had shown to exhibit different surface antigens altering their biological activity. Sera antibodies were analyzed by indirect immunofluorescence assay, and cell populations used in each assay were characterized by histological staining. The role of IgE in the cytotoxic attack against NBL was analyzed using heated serum. The FcεRI expression on cell suspensions was examined by flow cytometry. Results showed that lung cells were capable of killing NBL by antibody-dependent cell-mediated cytotoxicity (ADCC). Lung cells from infected animals yielded the highest mortality percentages of NBL, with NBL20 being the most susceptible to such attack. IgE yielded a critical role in the cytotoxic attack. Regarding the analysis of cell suspensions, cells from infected rats showed an increase in the percentage of eosinophils, neutrophils, and the number of cells expressing the FcεRI receptor. We conclude that lung cells are capable of killing NBL in the presence of specific antibodies, supporting the idea that the lung is one of the sites where the NBL death occurs due to ADCC.

The Neonatal Fc Receptor (FcRn) Enhances Human Immunodeficiency Virus Type 1 (HIV-1) Transcytosis across Epithelial Cells

PubMed Central

Gupta, Sandeep; Gach, Johannes S.; Becerra, Juan C.; Phan, Tran B.; Pudney, Jeffrey; Moldoveanu, Zina; Joseph, Sarah B.; Landucci, Gary; Supnet, Medalyn Jude; Ping, Li-Hua; Corti, Davide; Moldt, Brian; Hel, Zdenek; Lanzavecchia, Antonio; Ruprecht, Ruth M.; Burton, Dennis R.; Mestecky, Jiri; Anderson, Deborah J.; Forthal, Donald N.

2013-01-01

The mechanisms by which human immunodeficiency virus type 1 (HIV-1) crosses mucosal surfaces to establish infection are unknown. Acidic genital secretions of HIV-1-infected women contain HIV-1 likely coated by antibody. We found that the combination of acidic pH and Env-specific IgG, including that from cervicovaginal and seminal fluids of HIV-1-infected individuals, augmented transcytosis across epithelial cells as much as 20-fold compared with Env-specific IgG at neutral pH or non-specific IgG at either pH. Enhanced transcytosis was observed with clinical HIV-1 isolates, including transmitted/founder strains, and was eliminated in Fc neonatal receptor (FcRn)-knockdown epithelial cells. Non-neutralizing antibodies allowed similar or less transcytosis than neutralizing antibodies. However, the ratio of total:infectious virus was higher for neutralizing antibodies, indicating that they allowed transcytosis while blocking infectivity of transcytosed virus. Immunocytochemistry revealed abundant FcRn expression in columnar epithelia lining the human endocervix and penile urethra. Acidity and Env-specific IgG enhance transcytosis of virus across epithelial cells via FcRn and could facilitate translocation of virus to susceptible target cells following sexual exposure. PMID:24278022

[Limbic encephalitis with antibodies against intracellular antigens].

PubMed

Morita, Akihiko; Kamei, Satoshi

2010-04-01

Limbic encephalitis is a paraneoplastic syndrome that is often associated with small cell lung cancer (SCLC), breast cancer, testicular tumors, teratoma, Hodgkin's lymphoma and thymoma. The common clinical manifestations of limbic encephalitis are subacute onset, cognitive dysfunction, seizures and psychiatric symptoms. Paraneoplastic neurological disorders are considered to occur because of cytotoxic T cell responses and antibodies against target neuronal proteins that are usually expressed by an underlying tumor. The main intracellular antigens related to limbic encephalitis are Hu, Ma2, and less frequently CV2/CRMP5 and amphiphysin. The anti-Hu antibody, which is involved in cerebellar degeneration and extensive or multifocal encephalomyelitis such as limbic encephalitis is closely associated with a history of smoking and SCLC. The anti-Ma2 antibody is associated with encephalitis of the limbic system, hypothalamus and brain-stem. For this reason, some patients with limbic encephalitis have sleep disorders (including REM sleep abnormalities), severe hypokinesis and gaze palsy in addition to limbic dysfunction. In men aged less than 50 years, anti-Ma2 antibody encephalitis is almost always associated with testicular germ-cell tumors that are occasionally difficult to detect. In older men and women, the most common tumors are non-SCLC and breast cancer. Limbic encephalitis associated with cell-surface antigens (e.g., voltage-gated potassium channels, NMDA receptors) is mediated by antibodies and often improves after a reduction in the antibody titer and after tumor resection. Patients with antibodies against intracellular antigens, except for those with anti-Ma2 antibodies and testicular tumors, are less responsive. Early diagnosis and treatment with immunotherapy, tumor resection or both are important for improving or stabilizing the condition of limbic encephalitis.

Complement-Mediated Enhancement of Monocyte Adhesion to Endothelial Cells by HLA Antibodies, and Blockade by a Specific Inhibitor of the Classical Complement Cascade, TNT003

PubMed Central

Valenzuela, Nicole M.; Thomas, Kimberly A.; Mulder, Arend; Parry, Graham C.; Panicker, Sandip; Reed, Elaine F.

2017-01-01

Background Antibody-mediated rejection (AMR) of most solid organs is characterized by evidence of complement activation and/or intragraft macrophages (C4d + and CD68+ biopsies). We previously demonstrated that crosslinking of HLA I by antibodies triggered endothelial activation and monocyte adhesion. We hypothesized that activation of the classical complement pathway at the endothelial cell surface by HLA antibodies would enhance monocyte adhesion through soluble split product generation, in parallel with direct endothelial activation downstream of HLA signaling. Methods Primary human aortic endothelial cells (HAEC) were stimulated with HLA class I antibodies in the presence of intact human serum complement. C3a and C5a generation, endothelial P-selectin expression, and adhesion of human primary and immortalized monocytes (Mono Mac 6) were measured. Alternatively, HAEC or monocytes were directly stimulated with purified C3a or C5a. Classical complement activation was inhibited by pretreatment of complement with an anti-C1s antibody (TNT003). Results Treatment of HAEC with HLA antibody and human complement increased the formation of C3a and C5a. Monocyte recruitment by human HLA antibodies was enhanced in the presence of intact human serum complement or purified C3a or C5a. Specific inhibition of the classical complement pathway using TNT003 or C1q-depleted serum significantly reduced adhesion of monocytes in the presence of human complement. Conclusions Despite persistent endothelial viability in the presence of HLA antibodies and complement, upstream complement anaphylatoxin production exacerbates endothelial exocytosis and leukocyte recruitment. Upstream inhibition of classical complement may be therapeutic to dampen mononuclear cell recruitment and endothelial activation characteristic of microvascular inflammation during AMR. PMID:28640789

Heterotypic binding between neuronal membrane vesicles and glial cells is mediated by a specific cell adhesion molecule

PubMed Central

1984-01-01

By means of a multistage quantitative assay, we have identified a new kind of cell adhesion molecule (CAM) on neuronal cells of the chick embryo that is involved in their adhesion to glial cells. The assay used to identify the binding component (which we name neuron-glia CAM or Ng-CAM) was designed to distinguish between homotypic binding (e.g., neuron to neuron) and heterotypic binding (e.g., neuron to glia). This distinction was essential because a single neuron might simultaneously carry different CAMs separately mediating each of these interactions. The adhesion of neuronal cells to glial cells in vitro was previously found to be inhibited by Fab' fragments prepared from antisera against neuronal membranes but not by Fab' fragments against N-CAM, the neural cell adhesion molecule. This suggested that neuron-glia adhesion is mediated by specific cell surface molecules different from previously isolated CAMs . To verify that this was the case, neuronal membrane vesicles were labeled internally with 6-carboxyfluorescein and externally with 125I-labeled antibodies to N-CAM to block their homotypic binding. Labeled vesicles bound to glial cells but not to fibroblasts during a 30-min incubation period. The specific binding of the neuronal vesicles to glial cells was measured by fluorescence microscopy and gamma spectroscopy of the 125I label. Binding increased with increasing concentrations of both glial cells and neuronal vesicles. Fab' fragments prepared from anti-neuronal membrane sera that inhibited binding between neurons and glial cells were also found to inhibit neuronal vesicle binding to glial cells. The inhibitory activity of the Fab' fragments was depleted by preincubation with neuronal cells but not with glial cells. Trypsin treatment of neuronal membrane vesicles released material that neutralized Fab' fragment inhibition; after chromatography, neutralizing activity was enriched 50- fold. This fraction was injected into mice to produce monoclonal antibodies; an antibody was obtained that interacted with neurons, inhibited binding of neuronal membrane vesicles to glial cells, and recognized an Mr = 135,000 band in immunoblots of embryonic chick brain membranes. These results suggest that this molecule is present on the surfaces of neurons and that it directly or indirectly mediates adhesion between neurons and glial cells. Because the monoclonal antibody as well as the original polyspecific antibodies that were active in the assay did not bind to glial cells, we infer that neuron- glial interaction is heterophilic, i.e., it occurs between Ng-CAM on neurons and an as yet unidentified CAM present on glial cells. PMID:6725397

Active Immunizations with Peptide-DC Vaccines and Passive Transfer with Antibodies Protect Neutropenic Mice against Disseminated Candidiasis

PubMed Central

Xin, Hong

2015-01-01

We previously report that peptide-pulsed dendritic cell (DC) vaccination, which targeting two peptides (Fba and Met6) expressed on the cell surface of Candida albicans, can induce high degree of protection against disseminated candidiasis in immunocompetent mice. Passive transfer of immune sera from the peptide immunized mice or peptide-related monoclonal antibodies demonstrated that protection was medicated by peptide-specific antibodies. In this study the efficacy of active and passive immunization against disseminated candidiasis was tested in mice with cyclophosphamide-induced neutropenia. Peptide-DC vaccines were given to mice prior to induction of neutropenia. We show active immunization with either Fba or Met6 peptide-DC vaccine significantly improved the survival and reduced the fungal burden of disseminated candidiasis in those immunocompromised mice. Importantly, we show that administration of two protective monoclonal antibodies also protect neutropenic mice against the disease, implying possibility of developing a successful passive immunotherapy strategy to treat the disease and protect against disseminated candidiasis. The results of this study are crucial as they address the fundamental questions as to whether the synthetic peptide vaccine induced immunity protects the host during a neutropenic episode. We anticipate that this peptide-vaccine study will serve as the foundation of future investigations into new peptide vaccines comprised of cell surface peptides from other medically important Candida species, as well as other fungi. PMID:26620842

Switch from hapten-specific immunoglobulin M to immunoglobulin D secretion in a hybrid mouse cell line.

PubMed Central

Neuberger, M S; Rajewsky, K

1981-01-01

From a hybrid mouse cell line (B1-8) that secreted an IgM, lambda 1 anti-(4-hydroxy-3-nitrophenyl)acetyl antibody but that had no detectable surface IgM, selection for a variant with lambda 1 chains on the surface resulted in the isolation of a line that had switched from mu to delta expression. The surface and secreted Igs of this line were typed as IgD with two monoclonal antibodies, and the parental IgM and variant IgD molecules carried the same variable regions as judged by hapten-binding and idiotypic analysis. The surface and secreted delta chains of the IgD variant have apparent molecular weights of 64,000 and 61,000, respectively. However, the unglycosylated secreted delta polypeptide chain has a molecular weight of only 44,000. The secreted IgD exists predominantly in the delta 2 lambda A2 form, does not contain J protein, is relatively stable in serum, and does not fix complement. Images PMID:6940132

Development of Novel Monoclonal Antibodies that Define Differentiation Stages of Human Stromal (Mesenchymal) Stem Cells

PubMed Central

Andersen, Ditte C.; Kortesidis, Angela; Zannettino, Andrew C.W.; Kratchmarova, Irina; Chen, Li; Jensen, Ole N.; Teisner, Børge; Gronthos, Stan; Jensen, Charlotte H.; Kassem, Moustapha

2011-01-01

Human mesenchymal stem cells (hMSC) are currently being introduced for cell therapy, yet, antibodies specific for native and differentiated MSCs are required for their identification prior to clinical use. Herein, high quality antibodies against MSC surface proteins were developed by immunizing mice with hMSC, and by using a panel of subsequent screening methods. Flow cytometry analysis revealed that 83.5, 1.1, and 8.5% of primary cultures of hMSC were double positive for STRO-1 and either of DJ 3, 9, and 18, respectively. However, none of the three DJ antibodies allowed enrichment of clonogenic hMSC from BMMNCs as single reagents. Using mass-spectrometric analysis, we identified the antigen recognised by DJ3 as CD44, whereas DJ9 and DJ18 recognized HLA-DRB1 and Collagen VI, respectively. The identified proteins were highly expressed throughout in vitro osteogenic- and adipogenic differentiation. Interestingly, undifferentiated cells revealed a sole cytoplasmic distribution pattern of Collagen VI, which however changed to an extracellular matrix appearance upon osteogenic- and adipogenic differentiation. In relation to this, we found that STRO-1+/-/Collagen VI- sorted hMSC contained fewer differentiated alkaline phosphatase + cells compared to STRO-1+/-/Collagen VI+ hMSC, suggesting that Collagen VI on the cell membrane exclusively defines differentiated MSCs. In conclusion, we have generated a panel of high quality antibodies to be used for characterization of MSCs, and in addition our results may suggest that the DJ18 generated antibody against Collagen VI can be used for negative selection of cultured undifferentiated MSCs. PMID:21614487

Uninfected Bystander Cells Impact the Measurement of HIV-Specific Antibody-Dependent Cellular Cytotoxicity Responses

PubMed Central

Richard, Jonathan; Prévost, Jérémie; Baxter, Amy E.; Ding, Shilei; Medjahed, Halima; Delgado, Gloria G.; Brassard, Nathalie; Stürzel, Christina M.; Kirchhoff, Frank; Hahn, Beatrice H.; Parsons, Matthew S.; Kaufmann, Daniel E.; Evans, David T.

2018-01-01

ABSTRACT The conformation of the HIV-1 envelope glycoprotein (Env) substantially impacts antibody recognition and antibody-dependent cellular cytotoxicity (ADCC) responses. In the absence of the CD4 receptor at the cell surface, primary Envs sample a “closed” conformation that occludes CD4-induced (CD4i) epitopes. The virus controls CD4 expression through the actions of Nef and Vpu accessory proteins, thus protecting infected cells from ADCC responses. However, gp120 shed from infected cells can bind to CD4 present on uninfected bystander cells, sensitizing them to ADCC mediated by CD4i antibodies (Abs). Therefore, we hypothesized that these bystander cells could impact the interpretation of ADCC measurements. To investigate this, we evaluated the ability of antibodies to CD4i epitopes and broadly neutralizing Abs (bNAbs) to mediate ADCC measured by five ADCC assays commonly used in the field. Our results indicate that the uninfected bystander cells coated with gp120 are efficiently recognized by the CD4i ligands but not the bNabs. Consequently, the uninfected bystander cells substantially affect in vitro measurements made with ADCC assays that fail to identify responses against infected versus uninfected cells. Moreover, using an mRNA flow technique that detects productively infected cells, we found that the vast majority of HIV-1-infected cells in in vitro cultures or ex vivo samples from HIV-1-infected individuals are CD4 negative and therefore do not expose significant levels of CD4i epitopes. Altogether, our results indicate that ADCC assays unable to differentiate responses against infected versus uninfected cells overestimate responses mediated by CD4i ligands. PMID:29559570

Recombinant antibodies and their use in biosensors.

PubMed

Zeng, Xiangqun; Shen, Zhihong; Mernaugh, Ray

2012-04-01

Inexpensive, noninvasive immunoassays can be used to quickly detect disease in humans. Immunoassay sensitivity and specificity are decidedly dependent upon high-affinity, antigen-specific antibodies. Antibodies are produced biologically. As such, antibody quality and suitability for use in immunoassays cannot be readily determined or controlled by human intervention. However, the process through which high-quality antibodies can be obtained has been shortened and streamlined by use of genetic engineering and recombinant antibody techniques. Antibodies that traditionally take several months or more to produce when animals are used can now be developed in a few weeks as recombinant antibodies produced in bacteria, yeast, or other cell types. Typically most immunoassays use two or more antibodies or antibody fragments to detect antigens that are indicators of disease. However, a label-free biosensor, for example, a quartz-crystal microbalance (QCM) needs one antibody only. As such, the cost and time needed to design and develop an immunoassay can be substantially reduced if recombinant antibodies and biosensors are used rather than traditional antibody and assay (e.g. enzyme-linked immunosorbant assay, ELISA) methods. Unlike traditional antibodies, recombinant antibodies can be genetically engineered to self-assemble on biosensor surfaces, at high density, and correctly oriented to enhance antigen-binding activity and to increase assay sensitivity, specificity, and stability. Additionally, biosensor surface chemistry and physical and electronic properties can be modified to further increase immunoassay performance above and beyond that obtained by use of traditional methods. This review describes some of the techniques investigators have used to develop highly specific and sensitive, recombinant antibody-based biosensors for detection of antigens in simple or complex biological samples.

The Effects of Size, Shape, and Surface Functional Group of Gold Nanostructures on Their Adsorption and Internalization by Cells

PubMed Central

Cho, Eun Chul; Au, Leslie; Zhang, Qiang; Xia, Younan

2010-01-01

In this study, we examined the effects of size, shape, and surface chemistry of gold nanostructures on their uptake (including both adsorption and internalization) by SK-BR-3 breast cancer cells. We used both spherical and cubic Au nanostructures (nanospheres and nanocages, respectively) of two different sizes, and their surface was modified with poly(ethylene glycol) (PEG), antibody anti-HER2, or poly(allyamine hydrochloride) (PAA). Our results showed that the size of the Au nanostructures influenced their uptake by the cells in a similar way regardless of the surface chemistry, while the shape dependency could vary depending on the surface functional group. In addition, the cells preferred to take up the Au nanostructures covered by different surface groups in the following order: PAA>> anti-HER2> PEG. The fraction of Au nanostructures attached to the cell surface was also dependent on the aforementioned parameters. PMID:20029850

Enhanced Neutralization Potency of Botulinum Neurotoxin Antibodies Using a Red Blood Cell-Targeting Fusion Protein

PubMed Central

Adekar, Sharad P.; Segan, Andrew T.; Chen, Cindy; Bermudez, Rodney; Elias, M. D.; Selling, Bernard H.; Kapadnis, B. P.; Simpson, Lance L.; Simon, Paul M.; Dessain, Scott K.

2011-01-01

Botulinum neurotoxin (BoNT) potently inhibits cholinergic signaling at the neuromuscular junction. The ideal countermeasures for BoNT exposure are monoclonal antibodies or BoNT antisera, which form BoNT-containing immune complexes that are rapidly cleared from the general circulation. Clearance of opsonized toxins may involve complement receptor-mediated immunoadherence to red blood cells (RBC) in primates or to platelets in rodents. Methods of enhancing immunoadherence of BoNT-specific antibodies may increase their potency in vivo. We designed a novel fusion protein (FP) to link biotinylated molecules to glycophorin A (GPA) on the RBC surface. The FP consists of an scFv specific for murine GPA fused to streptavidin. FP:mAb:BoNT complexes bound specifically to the RBC surface in vitro. In a mouse model of BoNT neutralization, the FP increased the potency of single and double antibody combinations in BoNT neutralization. A combination of two antibodies with the FP gave complete neutralization of 5,000 LD50 BoNT in mice. Neutralization in vivo was dependent on biotinylation of both antibodies and correlated with a reduction of plasma BoNT levels. In a post-exposure model of intoxication, FP:mAb complexes gave complete protection from a lethal BoNT/A1 dose when administered within 2 hours of toxin exposure. In a pre-exposure prophylaxis model, mice were fully protected for 72 hours following administration of the FP:mAb complex. These results demonstrate that RBC-targeted immunoadherence through the FP is a potent enhancer of BoNT neutralization by antibodies in vivo. PMID:21399689

Identification of a major sialoprotein in the glycocalyx of human visceral glomerular epithelial cells.

PubMed Central

Kerjaschki, D; Poczewski, H; Dekan, G; Horvat, R; Balzar, E; Kraft, N; Atkins, R C

1986-01-01

Glomerular visceral epithelial cells are endowed with a sialic acid-rich surface coat (the "glomerular epithelial polyanion"), which in rat tissue contains the sialoprotein podocalyxin. We have identified a major membrane sialoprotein in human glomeruli that is similar to rat podocalyxin in its sialic acid-dependent binding of wheat germ agglutinin and in its localization on the surface of glomerular epithelial and endothelial cells, as shown by immunoelectron microscopy, using the monoclonal antibody PHM5. Differences in the sialoproteins of the two species are indicated by the discrepancy of their apparent molecular weights in sodium dodecyl sulfate gels, by the lack of cross reactivity of their specific antibodies, and by the lack of homology of their proteolytic peptide maps. It is therefore possible that the human glomerular sialoprotein and rat podocalyxin are evolutionarily distinct, but have similar functions. Images PMID:3533998

Construction of a hepatitis B virus neutralizing chimeric monoclonal antibody recognizing escape mutants of the viral surface antigen (HBsAg).

PubMed

Golsaz-Shirazi, Forough; Amiri, Mohammad Mehdi; Farid, Samira; Bahadori, Motahareh; Bohne, Felix; Altstetter, Sebastian; Wolff, Lisa; Kazemi, Tohid; Khoshnoodi, Jalal; Hojjat-Farsangi, Mohammad; Chudy, Michael; Jeddi-Tehrani, Mahmood; Protzer, Ulrike; Shokri, Fazel

2017-08-01

Hepatitis B virus (HBV) infection is a global burden on the health-care system and is considered as the tenth leading cause of death in the world. Over 248 million patients are currently suffering from chronic HBV infection worldwide and annual mortality rate of this infection is 686000. The "a" determinant is a hydrophilic region present in all antigenic subtypes of hepatitis B surface antigen (HBsAg), and antibodies against this region can neutralize the virus and are protective against all subtypes. We have recently generated a murine anti-HBs monoclonal antibody (4G4), which can neutralize HBV infection in HepaRG cells and recognize most of the escape mutant forms of HBsAg. Here, we describe the production and characterization of the chimeric human-murine antibody 4G4 (c-4G4). Variable region genes of heavy and light chains of the m-4G4 were cloned and fused to constant regions of human kappa and IgG1 by splice overlap extension (SOE) PCR. The chimeric antibody was expressed in Chinese Hamster Ovary (CHO)-K1 cells and purified from culture supernatant. Competition ELISA proved that both antibodies bind the same epitope within HBsAg. Antigen-binding studies using ELISA and Western blot showed that c-4G4 has retained the affinity and specificity of the parental murine antibody, and displayed a similar pattern of reactivity to 13 escape mutant forms of HBsAg. Both, the parental and c-4G4 showed a comparably high HBV neutralization capacity in cell culture even at the lowest concentration (0.6μg/ml). Due to the ability of c-4G4 to recognize most of the sub-genotypes and escape mutants of HBsAg, this antibody either alone or in combination with other anti-HBs antibodies could be considered as a potent alternative for Hepatitis B immune globulin (HBIG) as an HBV infection prophylactic or for passive immunotherapy against HBV infection. Copyright © 2017 Elsevier B.V. All rights reserved.

Functionality of Immunoglobulin G and Immunoglobulin M Antibody Physisorbed on Cellulosic Films

PubMed Central

Huang, Ziwei; Raghuwanshi, Vikram Singh; Garnier, Gil

2017-01-01

The functionality and aging mechanism of antibodies physisorbed onto cellulosic films was investigated. Blood grouping antibodies immunoglobulin G (IgG) and immunoglobulin M (IgM) were adsorbed onto smooth cellulose acetate (CAF) and regenerated cellulose (RCF) films. Cellulose films and adsorbed IgG layers were characterized at the air and liquid interface by X-ray and neutron reflectivity (NR), respectively. Cellulose film 208 Å thick (in air) swell to 386 Å once equilibrated in water. IgG adsorbs from solution onto cellulose as a partial layer 62 Å thick. IgG and IgM antibodies were adsorbed onto cellulose and cellulose acetate films, air dried, and aged at room temperature for periods up to 20 days. Antibody functionality and surface hydrophobicity were measured everyday with the size of red blood cell (RBC) agglutinates (using RBC specific to IgG/IgM) and the water droplet contact angle, respectively. The functionality of the aged IgG/IgM decreases faster if physisorbed on cellulose than on cellulose acetate and correlates to surface hydrophobicity. IgG physisorbed on RCF or CAF age better and remain functional longer than physisorbed IgM. We found a correlation between antibody stability and hydrogen bond formation ability of the system, evaluated from antibody carbonyl concentration and cellulosic surface hydroxyl concentration. Antibody physisorbs on cellulose by weak dipole forces and hydrogen bonds. Strong hydrogen bonding contributes to the physisorption of antibody on cellulose into a non-functional configuration in which the molecule relaxes by rotation of hydophobic groups toward the air interface. PMID:28770196

T Cell Epitope Regions of the P. falciparum MSP1-33 Critically Influence Immune Responses and In Vitro Efficacy of MSP1-42 Vaccines

PubMed Central

Pusic, Kae M.; Hashimoto, Caryn N.; Lehrer, Axel; Aniya, Charmaine; Clements, David E.; Hui, George S.

2011-01-01

The C-terminal 42 kDa fragments of the P. falciparum Merozoite Surface Protein 1, MSP1-42 is a leading malaria vaccine candidate. MSP1-33, the N-terminal processed fragment of MSP1-42, is rich in T cell epitopes and it is hypothesized that they enhance antibody response toward MSP1-19. Here, we gave in vivo evidence that T cell epitope regions of MSP1-33 provide functional help in inducing anti-MSP1-19 antibodies. Eleven truncated MSP1-33 segments were expressed in tandem with MSP1-19, and immunogenicity was evaluated in Swiss Webster mice and New Zealand White rabbits. Analyses of anti-MSP1-19 antibody responses revealed striking differences in these segments' helper function despite that they all possess T cell epitopes. Only a few fragments induced a generalized response (100%) in outbred mice. These were comparable to or surpassed the responses observed with the full length MSP1-42. In rabbits, only a subset of truncated antigens induced potent parasite growth inhibitory antibodies. Notably, two constructs were more efficacious than MSP1-42, with one containing only conserved T cell epitopes. Moreover, another T cell epitope region induced high titers of non-inhibitory antibodies and they interfered with the inhibitory activities of anti-MSP1-42 antibodies. In mice, this region also induced a skewed TH2 cellular response. This is the first demonstration that T cell epitope regions of MSP1-33 positively or negatively influenced antibody responses. Differential recognition of these regions by humans may play critical roles in vaccine induced and/or natural immunity to MSP1-42. This study provides the rational basis to re-engineer more efficacious MSP1-42 vaccines by selective inclusion and exclusion of MSP1-33 specific T cell epitopes. PMID:21931852

Dissemination of bovine leukemia virus-infected cells from a newly infected sheep lymph node.

PubMed

Fulton, B E; Portella, M; Radke, K

2006-08-01

To investigate the early establishment of bovine leukemia virus (BLV) infection, we injected BLV-infected or mock-infected allogeneic cells into the shoulder of sheep in which an efferent lymphatic duct of the draining prescapular lymph node had been cannulated. Rare mononuclear cells acting as centers of BLV infection in culture were present within 4 to 6 days in efferent lymph and within 6 to 10 days in blood. Soon after BLV injection, immunoglobulin M+ (IgM+) and CD8+ cells increased in efferent lymph and oscillated reciprocally in frequency. CD8+ blasts increased on days 4 to 6, when infectious centers increased 100-fold in lymph. On days 6 and 7, both lymph and blood were enriched with CD8+ cells that were labeled late on day 5 with an intravenous pulse of 5-bromo-2'-deoxyuridine (BrdU). Lymph, but not blood, was enriched with BrdU+ B cells on day 7. Capsid-specific antibodies became detectable in efferent lymph on days 6 to 8 and surface glycoprotein-specific antibodies on day 9, preceding their detection in serum by 9 to 14 days. Systemic dissemination of BLV-infected cells was thus accompanied by an increase in proliferating CD8+ cells and the onset of BLV-specific antibodies in lymph. Infectious centers reached maximum frequencies of 0.2% in lymph by days 11 to 13, and then their frequencies increased by 5- to 40-fold in blood cells, suggesting that many infected blood cells do not recirculate back into lymph. Beginning on days 10 to 13, a subpopulation of B cells having high levels of surface IgM increased sharply in peripheral blood. Such cells were not present in lymph. After a day 16 pulse of BrdU, recently proliferated cells that stained intensely for surface IgM appeared in blood within 15 h. Predominantly B lymphocytes contained the viral capsid protein when lymph and blood cells were cultured briefly to allow BLV expression. However, both early in lymph and later in blood, BrdU+ B cells greatly exceeded productively infected cells, indicating that new BLV infections stimulate proliferation of two different populations of B cells.

Surface decoration of red blood cells with maleimidophenyl-polyethylene glycol facilitated by thiolation with iminothiolane: an approach to mask A, B, and D antigens to generate universal red blood cells.

PubMed

Nacharaju, Parimala; Boctor, Fouad N; Manjula, Belur N; Acharya, Seetharama A

2005-03-01

The surface decoration of red blood cells (RBCs) by polyethylene glycol (PEG) chains has been an approach developed to camouflage the blood group antigens from their antibodies. A PEGylation protocol, however, that can mask the antigens appropriately to inhibit the agglutination of RBCs with the respective antibodies is not available so far. A new approach for PEGylation of RBC membrane proteins has been designed with thiolation-mediated maleimide chemistry. The accessibility of the surface lysine residues of membrane proteins to bulky PEG reagents was increased by linking an extension arm carrying a thiol group. RBCs have been PEGylated by thiolation-mediated chemistry with maleimidophenyl-PEG (Mal-Phe-PEG) reagents of different chain lengths. Mal-Phe-PEG-5000 chains alone masked the most important antigens of the Rh system (C, c, E, e, and D) from their antibodies. The masking of the A and B antigens needed a combination of Mal-Phe-PEG-5000 and Mal-Phe-PEG-20000 chains to inhibit the agglutination of RBCs completely with anti-A or anti-B. Thiolation-mediated PEGylation of RBCs with Mal-Phe-PEG-5000 and Mal-Phe-PEG-20000 converts Group A Rh(D)+ and B Rh(D)+ RBCs into RBCs with serologic behavior comparable to Group O Rh(D)- RBCs that are considered as universal RBCs for transfusion.

Expression of bovine non-classical major histocompatibility complex class I proteins in mouse P815 and human K562 cells.

PubMed

Parasar, Parveen; Wilhelm, Amanda; Rutigliano, Heloisa M; Thomas, Aaron J; Teng, Lihong; Shi, Bi; Davis, William C; Suarez, Carlos E; New, Daniel D; White, Kenneth L; Davies, Christopher J

2016-08-01

Major histocompatibility complex class I (MHC-I) proteins can be expressed as cell surface or secreted proteins. To investigate whether bovine non-classical MHC-I proteins are expressed as cell surface or secreted proteins, and to assess the reactivity pattern of monoclonal antibodies with non-classical MHC-I isoforms, we expressed the MHC proteins in murine P815 and human K562 (MHC-I deficient) cells. Following antibiotic selection, stably transfected cell lines were stained with H1A or W6/32 antibodies to detect expression of the MHC-I proteins by flow cytometry. Two non-classical proteins (BoLA-NC1*00501 and BoLA-NC3*00101) were expressed on the cell surface in both cell lines. Surprisingly, the BoLA-NC4*00201 protein was expressed on the cell membrane of human K562 but not mouse P815 cells. Two non-classical proteins (BoLA-NC1*00401, which lacks a transmembrane domain, and BoLA-NC2*00102) did not exhibit cell surface expression. Nevertheless, Western blot analyses demonstrated expression of the MHC-I heavy chain in all transfected cell lines. Ammonium-sulfate precipitation of proteins from culture supernatants showed that BoLA-NC1*00401 was secreted and that all surface expressed proteins where shed from the cell membrane by the transfected cells. Interestingly, the surface expressed MHC-I proteins were present in culture supernatants at a much higher concentration than BoLA-NC1*00401. This comprehensive study shows that bovine non-classical MHC-I proteins BoLA-NC1*00501, BoLA-NC3*00101, and BoLA-NC4*00201 are expressed as surface isoforms with the latter reaching the cell membrane only in K562 cells. Furthermore, it demonstrated that BoLA-NC1*00401 is a secreted isoform and that significant quantities of membrane associated MHC-I proteins can be shed from the cell membrane. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Translocalized IgA mediates neutralization and stimulates innate immunity inside infected cells

PubMed Central

Bidgood, Susanna R.; Tam, Jerry C. H.; McEwan, William A.; Mallery, Donna L.; James, Leo C.

2014-01-01

IgA is the most prevalent antibody type on mucosal surfaces and the second most prevalent antibody in circulation, yet its role in immune defense is not fully understood. Here we show that IgA is carried inside cells during virus infection, where it activates intracellular virus neutralization and innate immune signaling. Cytosolic IgA–virion complexes colocalize with the high-affinity antibody receptor tripartite motif-containing protein 21 (TRIM21) and are positive for lysine-48 ubiquitin chains. IgA neutralizes adenovirus infection in a TRIM21- and proteasome-dependent manner in both human and mouse cells. Translocated IgA also potently activates NF-κB signaling pathways in cells expressing TRIM21, whereas viral infection in the absence of antibody or TRIM21 is undetected. TRIM21 recognizes an epitope in IgG Fc that is not conserved in IgA; however, fluorescence anisotropy experiments demonstrate that direct binding to IgA is maintained. We use molecular modeling to show that TRIM21 forms a nonspecific hydrophobic seal around a β-loop structure that is present in IgG, IgM, and IgA, explaining how TRIM21 achieves such remarkable broad antibody specificity. The findings demonstrate that the antiviral protection afforded by IgA extends to the intracellular cytosolic environment. PMID:25169018

Translocalized IgA mediates neutralization and stimulates innate immunity inside infected cells.

PubMed

Bidgood, Susanna R; Tam, Jerry C H; McEwan, William A; Mallery, Donna L; James, Leo C

2014-09-16

IgA is the most prevalent antibody type on mucosal surfaces and the second most prevalent antibody in circulation, yet its role in immune defense is not fully understood. Here we show that IgA is carried inside cells during virus infection, where it activates intracellular virus neutralization and innate immune signaling. Cytosolic IgA-virion complexes colocalize with the high-affinity antibody receptor tripartite motif-containing protein 21 (TRIM21) and are positive for lysine-48 ubiquitin chains. IgA neutralizes adenovirus infection in a TRIM21- and proteasome-dependent manner in both human and mouse cells. Translocated IgA also potently activates NF-κB signaling pathways in cells expressing TRIM21, whereas viral infection in the absence of antibody or TRIM21 is undetected. TRIM21 recognizes an epitope in IgG Fc that is not conserved in IgA; however, fluorescence anisotropy experiments demonstrate that direct binding to IgA is maintained. We use molecular modeling to show that TRIM21 forms a nonspecific hydrophobic seal around a β-loop structure that is present in IgG, IgM, and IgA, explaining how TRIM21 achieves such remarkable broad antibody specificity. The findings demonstrate that the antiviral protection afforded by IgA extends to the intracellular cytosolic environment.

Paraneoplastic syndromes and autoimmune encephalitis

PubMed Central

Rosenfeld, Myrna R.; Titulaer, Maarten J.

2012-01-01

Summary We review novel findings in paraneoplastic syndromes including the Lambert-Eaton myasthenic syndrome, and then focus on the novel disorders associated with antibodies against cell surface antigens, discussing the importance and caveats of antibody testing, and providing an algorithm for interpretation of results. In anti-NMDAR encephalitis 2 novel findings include the recognition of a characteristic EEG pattern (“extreme delta brush”) in 30% of patients and the demonstration of a fronto-temporo-occipital gradient of glucose metabolism that correlates with disease activity. In limbic encephalitis, antibodies to GABA(B) receptor are the most frequently detected in patients with small-cell lung cancer who are anti-Hu negative, and antibodies to mGluR5 distinctively associate with Hodgkin lymphoma (Ophelia syndrome). We also address the syndromes associated with “VGKC-complex antibodies,” a problematic term that groups well-characterized immune-mediated disorders (LGI1, Caspr2) with others that lack syndrome specificity, are less responsive to treatment, and for which the target antigens are unknown. PMID:23634368

Role of framework mutations and antibody flexibility in the evolution of broadly neutralizing antibodies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ovchinnikov, Victor; Louveau, Joy E.; Barton, John P.

Eliciting antibodies that are cross reactive with surface proteins of diverse strains of highly mutable pathogens (e.g., HIV, influenza) could be key for developing effective universal vaccines. Mutations in the framework regions of such broadly neutralizing antibodies (bnAbs) have been reported to play a role in determining their properties. We used molecular dynamics simulations and models of affinity maturation to study specific bnAbs against HIV. Our results suggest that there are different classes of evolutionary lineages for the bnAbs. If germline B cells that initiate affinity maturation have high affinity for the conserved residues of the targeted epitope, framework mutationsmore » increase antibody rigidity as affinity maturation progresses to evolve bnAbs. If the germline B cells exhibit weak/moderate affinity for conserved residues, an initial increase in flexibility via framework mutations may be required for the evolution of bnAbs. Subsequent mutations that increase rigidity result in highly potent bnAbs. Implications of our results for immunogen design are discussed.« less

Role of framework mutations and antibody flexibility in the evolution of broadly neutralizing antibodies

DOE PAGES

Ovchinnikov, Victor; Louveau, Joy E.; Barton, John P.; ...

2018-02-14

Eliciting antibodies that are cross reactive with surface proteins of diverse strains of highly mutable pathogens (e.g., HIV, influenza) could be key for developing effective universal vaccines. Mutations in the framework regions of such broadly neutralizing antibodies (bnAbs) have been reported to play a role in determining their properties. We used molecular dynamics simulations and models of affinity maturation to study specific bnAbs against HIV. Our results suggest that there are different classes of evolutionary lineages for the bnAbs. If germline B cells that initiate affinity maturation have high affinity for the conserved residues of the targeted epitope, framework mutationsmore » increase antibody rigidity as affinity maturation progresses to evolve bnAbs. If the germline B cells exhibit weak/moderate affinity for conserved residues, an initial increase in flexibility via framework mutations may be required for the evolution of bnAbs. Subsequent mutations that increase rigidity result in highly potent bnAbs. Implications of our results for immunogen design are discussed.« less

Role of framework mutations and antibody flexibility in the evolution of broadly neutralizing antibodies

PubMed Central

2018-01-01

Eliciting antibodies that are cross reactive with surface proteins of diverse strains of highly mutable pathogens (e.g., HIV, influenza) could be key for developing effective universal vaccines. Mutations in the framework regions of such broadly neutralizing antibodies (bnAbs) have been reported to play a role in determining their properties. We used molecular dynamics simulations and models of affinity maturation to study specific bnAbs against HIV. Our results suggest that there are different classes of evolutionary lineages for the bnAbs. If germline B cells that initiate affinity maturation have high affinity for the conserved residues of the targeted epitope, framework mutations increase antibody rigidity as affinity maturation progresses to evolve bnAbs. If the germline B cells exhibit weak/moderate affinity for conserved residues, an initial increase in flexibility via framework mutations may be required for the evolution of bnAbs. Subsequent mutations that increase rigidity result in highly potent bnAbs. Implications of our results for immunogen design are discussed. PMID:29442996

Specific Uptake of Lipid-Antibody-Functionalized LbL Microcarriers by Cells.

PubMed

Göse, Martin; Scheffler, Kira; Reibetanz, Uta

2016-11-14

The modular construction of Layer-by-Layer biopolymer microcarriers facilitates a highly specific design of drug delivery systems. A supported lipid bilayer (SLB) contributes to biocompatibility and protection of sensitive active agents. The addition of a lipid anchor equipped with PEG (shielding from opsonins) and biotin (attachment of exchangeable outer functional molecules) enhances the microcarrier functionality even more. However, a homogeneously assembled supported lipid bilayer is a prerequisite for a specific binding of functional components. Our investigations show that a tightly packed SLB improves the efficiency of functional components attached to the microcarrier's surface, as illustrated with specific antibodies in cellular application. Only a low quantity of antibodies is needed to obtain improved cellular uptake rates independent from cell type as compared to an antibody-functionalized loosely packed lipid bilayer or directly assembled antibody onto the multilayer. A fast disassembly of the lipid bilayer within endolysosomes exposing the underlying drug delivering multilayer structure demonstrates the suitability of LbL-microcarriers as a multifunctional drug delivery system.

Uninfected Bystander Cells Impact the Measurement of HIV-Specific Antibody-Dependent Cellular Cytotoxicity Responses.

PubMed

Richard, Jonathan; Prévost, Jérémie; Baxter, Amy E; von Bredow, Benjamin; Ding, Shilei; Medjahed, Halima; Delgado, Gloria G; Brassard, Nathalie; Stürzel, Christina M; Kirchhoff, Frank; Hahn, Beatrice H; Parsons, Matthew S; Kaufmann, Daniel E; Evans, David T; Finzi, Andrés

2018-03-20

The conformation of the HIV-1 envelope glycoprotein (Env) substantially impacts antibody recognition and antibody-dependent cellular cytotoxicity (ADCC) responses. In the absence of the CD4 receptor at the cell surface, primary Envs sample a "closed" conformation that occludes CD4-induced (CD4i) epitopes. The virus controls CD4 expression through the actions of Nef and Vpu accessory proteins, thus protecting infected cells from ADCC responses. However, gp120 shed from infected cells can bind to CD4 present on uninfected bystander cells, sensitizing them to ADCC mediated by CD4i antibodies (Abs). Therefore, we hypothesized that these bystander cells could impact the interpretation of ADCC measurements. To investigate this, we evaluated the ability of antibodies to CD4i epitopes and broadly neutralizing Abs (bNAbs) to mediate ADCC measured by five ADCC assays commonly used in the field. Our results indicate that the uninfected bystander cells coated with gp120 are efficiently recognized by the CD4i ligands but not the bNabs. Consequently, the uninfected bystander cells substantially affect in vitro measurements made with ADCC assays that fail to identify responses against infected versus uninfected cells. Moreover, using an mRNA flow technique that detects productively infected cells, we found that the vast majority of HIV-1-infected cells in in vitro cultures or ex vivo samples from HIV-1-infected individuals are CD4 negative and therefore do not expose significant levels of CD4i epitopes. Altogether, our results indicate that ADCC assays unable to differentiate responses against infected versus uninfected cells overestimate responses mediated by CD4i ligands. IMPORTANCE Emerging evidence supports a role for antibody-dependent cellular cytotoxicity (ADCC) in protection against HIV-1 transmission and disease progression. However, there are conflicting reports regarding the ability of nonneutralizing antibodies targeting CD4-inducible (CD4i) Env epitopes to mediate ADCC. Here, we performed a side-by-side comparison of different methods currently being used in the field to measure ADCC responses to HIV-1. We found that assays which are unable to differentiate virus-infected from uninfected cells greatly overestimate ADCC responses mediated by antibodies to CD4i epitopes and underestimate responses mediated by broadly neutralizing antibodies (bNAbs). Our results strongly argue for the use of assays that measure ADCC against HIV-1-infected cells expressing physiologically relevant conformations of Env to evaluate correlates of protection in vaccine trials. Copyright © 2018 Richard et al.

Translation and assembly of HLA-DR antigens in Xenopus oocytes injected with mRNA from a human B-cell line.

PubMed Central

Long, E O; Gross, N; Wake, C T; Mach, J P; Carrel, S; Accolla, R; Mach, B

1982-01-01

HLA-DR antigens are polymorphic cell surface glycoproteins, expressed primarily in B lymphocytes and macrophages, which are thought to play an important role in the immune response. Two polypeptide chains, alpha and beta, are associated at the cell surface, and a third chain associates with alpha and beta intracellularly. RNA isolated from the human B-cell line Raji was injected in Xenopus laevis oocytes. Immunoprecipitates of translation products with several monoclonal antibodies revealed the presence of HLA-DR antigens similar to those synthesized in Raji cells. One monoclonal antibody was able to bind the beta chain after dissociation of the three polypeptide chains with detergent. The presence of all three chains was confirmed by two-dimensional gel electrophoresis. The glycosylation pattern of the three chains was identical to that observed in vivo, as evidenced in studies using tunicamycin, an inhibitor of N-linked glycosylation. The presence of alpha chains assembled with beta chains in equimolar ratio was further demonstrated by amino-terminal sequencing. An RNA fraction enriched for the three mRNAs, encoding alpha, beta, and intracellular chains, was isolated. This translation-assembly system and the availability of monoclonal antibodies make it possible to assay for mRNA encoding specific molecules among the multiple human Ia-like antigens. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. PMID:6821356

Evidence for idiotypic- and antiidiotypic B-B cellular interaction with the use of cloned antiidiotypic B cell line.

PubMed

Bitoh, S; Fujimoto, S; Yamamoto, H

1990-03-15

Immunization of BALB/c mice with MOPC104E myeloma protein induces antiidiotypic B lymphocytes that have Id-specific enhancing activity on antibody production. The B-B cell interaction was restricted to both Igh and class II MHC. However, anti-Thy-1 and C-treated splenic B cells were maintained for more than 1 y in a mixture of Con A-stimulated splenocyte culture supernatant and synthetic medium. In applying the long term culture method, we have established a cloned B cell line named B19-1d, B19-1d cells are specific to MOPC104E or J558 cross-reactive Id and they express surface mu, lambda but no Ly-1. B19-1d do not spontaneously secrete Ig but produce them upon stimulation with bacterial LPS. The effect of B19-1d cell line on idiotypic antibody production was tested. Addition of only 10 to 100 B19-1d cells into dextran-immune B cell culture greatly enhanced the Id+ antidextran antibody responses. On the contrary, the antidextran antibody production was suppressed by the higher doses of B19-1d cells. The effective cooperation between dextran-immune B cells and B19-1d cloned B cells was restricted to class II MHC. The role of idiotypic- and antiidiotypic B-B cell interaction in immune regulation and repertoire generation was suggested.

Video Views and Reviews

ERIC Educational Resources Information Center

Watters, Christopher

2003-01-01

Neutrophils are white blood cells specialized for scavenging cellular debris and consuming infectious microorganisms in a process called "phagocytosis." What seems to make neutrophils especially voracious is the presence of antibodies (or opsonins) coating the surface of foreign cells. Recently, Dewitt and Hallett (2002) examined the role of…

Autonomous molecular cascades for evaluation of cell surfaces

NASA Astrophysics Data System (ADS)

Rudchenko, Maria; Taylor, Steven; Pallavi, Payal; Dechkovskaia, Alesia; Khan, Safana; Butler, Vincent P., Jr.; Rudchenko, Sergei; Stojanovic, Milan N.

2013-08-01

Molecular automata are mixtures of molecules that undergo precisely defined structural changes in response to sequential interactions with inputs. Previously studied nucleic acid-based automata include game-playing molecular devices (MAYA automata) and finite-state automata for the analysis of nucleic acids, with the latter inspiring circuits for the analysis of RNA species inside cells. Here, we describe automata based on strand-displacement cascades directed by antibodies that can analyse cells by using their surface markers as inputs. The final output of a molecular automaton that successfully completes its analysis is the presence of a unique molecular tag on the cell surface of a specific subpopulation of lymphocytes within human blood cells.

Effective combination treatment of GD2-expressing neuroblastoma and Ewing's sarcoma using anti-GD2 ch14.18/CHO antibody with Vγ9Vδ2+ γδT cells.

PubMed

Fisher, Jonathan P H; Flutter, Barry; Wesemann, Florian; Frosch, Jennifer; Rossig, Claudia; Gustafsson, Kenth; Anderson, John

Gamma delta T lymphocytes (γδT cells) have pleiotropic properties including innate cytotoxicity, which make them attractive effectors for cancer immunotherapy. Combination treatment with zoledronic acid and IL-2 can activate and expand the most common subset of blood γδT, which express the Vγ9Vδ2 T cell receptor (TCR) (Vδ2 T cells). Vγ9Vδ2 T cells are equipped for antibody-dependent cell-mediated cytotoxicity (ADCC) through expression of the low-affinity FcγR CD16. GD2 is a highly ranked tumor associated antigen for immunotherapy due to bright expression on the cell surface, absent expression on normal tissues and availability of therapeutic antibodies with known efficacy in neuroblastoma. To explore the hypothesis that zoledronic acid, IL-2 and anti-GD2 antibodies will synergize in a therapeutic combination, we evaluated in vitro cytotoxicity and tumor growth inhibition in the GD2 expressing cancers neuroblastoma and Ewing's sarcoma. Vδ2 T cells exert ADCC against GD2-expressing Ewing's sarcoma and neuroblastoma cell lines, an effect which correlates with the brightness of GD2 expression. In an immunodeficient mouse model of small established GD2-expressing Ewing's sarcoma or neuroblastoma tumors, the combination of adoptively transferred Vδ2+ T cells, expanded in vitro with zoledronic acid and IL-2, with anti-GD2 antibody ch14.18/CHO, and with systemic zoledronic acid, significantly suppressed tumor growth compared to antibody or γδT cell-free controls. Combination treatment using ch14.18/CHO, zoledronic acid and IL-2 is more effective than their use in isolation. The already-established safety profiles of these agents make testing of the combination in GD2 positive cancers such as neuroblastoma or Ewing's sarcoma both rational and feasible.

Effective combination treatment of GD2-expressing neuroblastoma and Ewing's sarcoma using anti-GD2 ch14.18/CHO antibody with Vγ9Vδ2+ γδT cells

PubMed Central

Fisher, Jonathan P H; Flutter, Barry; Wesemann, Florian; Frosch, Jennifer; Rossig, Claudia; Gustafsson, Kenth; Anderson, John

2016-01-01

Gamma delta T lymphocytes (γδT cells) have pleiotropic properties including innate cytotoxicity, which make them attractive effectors for cancer immunotherapy. Combination treatment with zoledronic acid and IL-2 can activate and expand the most common subset of blood γδT, which express the Vγ9Vδ2 T cell receptor (TCR) (Vδ2 T cells). Vγ9Vδ2 T cells are equipped for antibody-dependent cell-mediated cytotoxicity (ADCC) through expression of the low-affinity FcγR CD16. GD2 is a highly ranked tumor associated antigen for immunotherapy due to bright expression on the cell surface, absent expression on normal tissues and availability of therapeutic antibodies with known efficacy in neuroblastoma. To explore the hypothesis that zoledronic acid, IL-2 and anti-GD2 antibodies will synergize in a therapeutic combination, we evaluated in vitro cytotoxicity and tumor growth inhibition in the GD2 expressing cancers neuroblastoma and Ewing's sarcoma. Vδ2 T cells exert ADCC against GD2-expressing Ewing's sarcoma and neuroblastoma cell lines, an effect which correlates with the brightness of GD2 expression. In an immunodeficient mouse model of small established GD2-expressing Ewing's sarcoma or neuroblastoma tumors, the combination of adoptively transferred Vδ2+ T cells, expanded in vitro with zoledronic acid and IL-2, with anti-GD2 antibody ch14.18/CHO, and with systemic zoledronic acid, significantly suppressed tumor growth compared to antibody or γδT cell-free controls. Combination treatment using ch14.18/CHO, zoledronic acid and IL-2 is more effective than their use in isolation. The already-established safety profiles of these agents make testing of the combination in GD2 positive cancers such as neuroblastoma or Ewing's sarcoma both rational and feasible. PMID:26942051

Influence of IgG Subclass on Human Antimannan Antibody-Mediated Resistance to Hematogenously Disseminated Candidiasis in Mice

PubMed Central

Nishiya, Casey T.; Boxx, Gayle M.; Robison, Kerry; Itatani, Carol; Kozel, Thomas R.

2015-01-01

Candida albicans is a yeast-like pathogen and can cause life-threatening systemic candidiasis. Its cell surface is enriched with mannan that is resistant to complement activation. Previously, we developed the recombinant human IgG1 antimannan antibody M1g1. M1g1 was found to promote complement activation and phagocytosis and protect mice from systemic candidiasis. Here, we evaluate the influence of IgG subclass on antimannan antibody-mediated protection. Three IgG subclass variants of M1g1 were constructed: M1g2, M1g3, and M1g4. The IgG subclass identity for each variant was confirmed with DNA sequence and subclass-specific antibodies. These variants contain identical M1 Fabs and exhibited similar binding affinities for C. albicans yeast and purified mannan. Yeast cells and hyphae recovered from the kidney of antibody-treated mice with systemic candidiasis showed uniform binding of each variant, indicating constitutive expression of the M1 epitope and antibody opsonization in the kidney. All variants promoted deposition of both murine and human C3 onto the yeast cell surface, with M1g4 showing delayed activation, as determined by flow cytometry and immunofluorescence microscopy. M1g4-mediated complement activation was found to be associated with its M1 Fab that activates the alternative pathway in an Fc-independent manner. Treatment with each subclass variant extended the survival of mice with systemic candidiasis (P < 0.001). However, treatment with M1g1, M1g3, or M1g4, but not with M1g2, also reduced the kidney fungal burden (P < 0.001). Thus, the role of human antimannan antibody in host resistance to systemic candidiasis is influenced by its IgG subclass. PMID:26573736

Nano-particle enhanced impedimetric biosensor for detedtion of foodborne pathogens

NASA Astrophysics Data System (ADS)

Kim, G.; Om, A. S.; Mun, J. H.

2007-03-01

Recent outbreaks of foodborne illness have been increased the need for rapid and sensitive methods for detection of these pathogens. Conventional methods for pathogens detection and identification involve prolonged multiple enrichment steps. Even though some immunological rapid assays are available, these assays still need enrichment steps result in delayed detection. Biosensors have shown great potential for rapid detection of foodborne pathogens. They are capable of direct monitoring the antigen-antibody reactions in real time. Among the biosensors, impedimetric biosensors have been widely adapted as an analysis tool for the study of various biological binding reactions because of their high sensitivity and reagentless operation. In this study a nanoparticle-enhanced impedimetric biosensor for Salmonella enteritidis detection was developed which detected impedance changes caused by the attachment of the cells to the anti-Salmonella antibodies immobilized on interdigitated gold electrodes. Successive immobilization of neutravidin followed by anti-Salmonella antibodies was performed to the sensing area to create a biological detection surface. To enhance the impedance responses generated by antigen-antibody reactions, anti-Salmonella antibody conjugated nanoparticles were introduced on the sensing area. Using a portable impedance analyzer, the impedance across the interdigital electrodes was measured after the series of antigen-antibody bindings. Bacteria cells present in solution attached to capture antibodies and became tethered to the sensor surface. Attached bacteria cells changed the dielectric constant of the media between the electrodes thereby causing a change in measured impedance. Optimum input frequency was determined by analyzing frequency characteristics of the biosensor over ranges of applied frequencies from 10 Hz to 400 Hz. At 100 Hz of input frequency, the biosensor was most sensitive to the changes of the bacteria concentration and this frequency was used for the detection experiments. The biosensor was able to detect 106 CFU/mL in phosphate buffered saline (PBS) with a detection time of 3 minutes. Additional use of nanoparticles significantly enhanced the detection performance. By using the nanoparticles the biosensor could detect 104 CFU/mL of Salmonella enteritidis in PBS and 105 CFU/mL of cells in milk.

Cosmos: 1989 immunology studies

NASA Technical Reports Server (NTRS)

Sonnenfeld, Gerald

1991-01-01

The effects of flight on Cosmos mission 2044 on leukocyte subset distribution and the sensitivity of bone marrow cells to colony stimulating factor-GM were determined. A parallel study with antiorthostatic suspension was also carried out. The study involved repetition and expansion of studies performed on Cosmos 1887. Spleen and bone marrow cells were obtained from flown, vivarium control, synchronous control, and suspended rats. The cells were stained with a series of monoclonal antibodies directed against rat leukocyte cell surface antigens. Control cells were stained with a monoclonal antibody directed against an irrelevant species or were unstained. Cells were then analyzed for fluorescence using a FACSCAN flow cytometer. Bone marrow cells were placed in culture with GM-CSF in McCoy's 5a medium and incubated for 5 days. Cultures were then evaluated for the number of colonies of 50 cells or greater.

Purification of HBsAg produced by the human hepatoma cell line PLC/PRE/5 by affinity chromatography using monoclonal antibodies and application for ELISA diagnostic.

PubMed

Merten, O W; Reiter, S; Scheirer, W; Katinger, H

1983-01-01

The human cell line PLC/PRF/5 (5) was used for the production of hepatitis B surface antigen subtype ad (HBsAg ad) and purified by affinity chromatography (AC) with monoclonal antibodies (mAb). mAb to HBsAg from mouse ascites have been purified by Protein A - AC prior coupling to AH-Sepharose 4B (Pharmacia). The combined procedure of ammonium-sulphate-precipitation of HBsAg from culture supernatants and immunosorbent-AC leads to approx. 700-fold purification. ELISA results using the mAb and the HBsAg for diagnostics of human serum, positive for anti-HBsAg-antibodies correlate with the RIA (AUSAB, Abbott).

Cerebral distribution of immunoconjugate after treatment for neoplastic meningitis using an intrathecal radiolabeled monoclonal antibody

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benjamin, J.C.; Moss, T.; Moseley, R.P.

1989-08-01

A detailed autopsy and autoradiographic study was performed after the death of a patient undergoing intrathecal, antibody-guided irradiation for carcinomatous meningitis. The results demonstrated tumor cells infiltrating the surface meninges and a severe astrocytic reaction associated with oedema in the periventricular and brain stem subpial white matter. This was not seen in cortical or other gray matter structures. Autoradiographic examination correlated well, demonstrating isotope within the oedematous areas of the white matter in addition to the expected concentration in the leptomeningeal layers. These findings are discussed in the context of antibody binding to tumor tissue and the possible benefits conferredmore » in the treatment of infiltrating tumor cells.« less

Nanostructure and force spectroscopy analysis of human peripheral blood CD4{sup +} T cells using atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu Mingqian; Wang Jiongkun; Cai Jiye

2008-09-12

To date, nanoscale imaging of the morphological changes and adhesion force of CD4{sup +} T cells during in vitro activation remains largely unreported. In this study, we used atomic force microscopy (AFM) to study the morphological changes and specific binding forces in resting and activated human peripheral blood CD4{sup +} T cells. The AFM images revealed that the volume of activated CD4{sup +} T cells increased and the ultrastructure of these cells also became complex. Using a functionalized AFM tip, the strength of the specific binding force of the CD4 antigen-antibody interaction was found to be approximately three times thatmore » of the unspecific force. The adhesion forces were not randomly distributed over the surface of a single activated CD4{sup +} T cell, indicated that the CD4 molecules concentrated into nanodomains. The magnitude of the adhesion force of the CD4 antigen-antibody interaction did not change markedly with the activation time. Multiple bonds involved in the CD4 antigen-antibody interaction were measured at different activation times. These results suggest that the adhesion force involved in the CD4 antigen-antibody interaction is highly selective and of high affinity.« less

Detection of LGI1 and CASPR2 antibodies with a commercial cell-based assay in patients with very high VGKC-complex antibody levels.

PubMed

Yeo, T; Chen, Z; Chai, J Y H; Tan, K

2017-07-15

The presence of VGKC-complex antibodies, without LGI1/CASPR2 antibodies, as a standalone marker for neurological autoimmunity remains controversial. Additionally, the lack of an unequivocal VGKC-complex antibody cut-off level defining neurological autoimmunity makes it important to test for monospecific antibodies. We aim to determine the performance characteristics of a commercial assay (Euroimmun, Lübeck, Germany) for LGI1/CASPR2 antibody detection in patients with very high VGKC-complex antibody levels and report their clinico-serological associations. We identified 8 patients in our cohort with the highest VGKC-complex antibody levels (median 2663.5pM, range 933-6730pM) with VGKC-complex antibody related syndromes (Group A). Two other groups were identified; 1 group with suspected neuronal surface antibody syndromes and negative for VGKC-complex antibodies (Group B, n=8), and another group with cerebellar ataxia and negative for onconeuronal antibodies (Group C, n=8). Seven out of 8 patients (87.5%) in Group A had LGI1 and/or CASPR2 antibodies. One Group B patient had LGI1 antibodies but was negative on re-testing with a live cell assay. No Group C patients had monospecific antibodies. Inter-rater reliability was high; combining Groups A and B patients, the kappa statistic was 0.87 and 1.0 for LGI1 and CASPR2 antibodies respectively. We demonstrated that a high proportion of patients with very high VGKC-complex antibody levels and relevant clinical syndromes have LGI1 and/or CASPR2 antibodies detected by the commercial assay. Our findings lend support to the use of the assay for rapid and reliable detection of LGI1 and CASPR2 antibodies. Copyright © 2017 Elsevier B.V. All rights reserved.

Transient partial permeabilization with saponin enables cellular barcoding prior to surface marker staining1

PubMed Central

Behbehani, Gregory K.; Thom, Colin; Zunder, Eli R.; Finck, Rachel; Gaudilliere, Brice; Fragiadakis, Gabriela K.; Fantl, Wendy J.; Nolan, Garry P.

2015-01-01

Fluorescent cellular barcoding and mass-tag cellular barcoding are cytometric methods that enable high sample throughput, minimize inter-sample variation, and reduce reagent consumption. Previously employed barcoding protocols require that barcoding be performed after surface marker staining, complicating combining the technique with measurement of alcohol-sensitive surface epitopes. This report describes a method of barcoding fixed cells after a transient partial permeabilization with 0.02% saponin that results in efficient and consistent barcode staining with fluorescent or mass-tagged reagents while preserving surface marker staining. This approach simplifies barcoding protocols and allows direct comparison of surface marker staining of multiple samples without concern for variations in the antibody cocktail volume, antigen-antibody ratio, or machine sensitivity. Using this protocol, cellular barcoding can be used to reliably detect subtle differences in surface marker expression. PMID:25274027

Characterisation of a monoclonal antibody detecting Atlantic salmon endothelial and red blood cells, and its association with the infectious salmon anaemia virus cell receptor.

PubMed

Aamelfot, Maria; Weli, Simon C; Dale, Ole B; Koppang, Erling O; Falk, Knut

2013-05-01

Endothelial cells (ECs) line the luminal surfaces of the cardiovascular system and play an important role in cardiovascular functions such as regulation of haemostasis and vasomotor tone. A number of fish and mammalian viruses target these cells in the course of their infection. Infectious salmon anaemia virus (ISAV) attacks ECs and red blood cells (RBCs) of farmed Atlantic salmon (Salmo salar L.), producing the severe disease of infectious salmon anaemia (ISA). The investigation of ISA has up to now been hampered by the lack of a functional marker for ECs in Atlantic salmon in situ. In this study, we report the characterisation and use of a novel monoclonal antibody (MAb) detecting Atlantic salmon ECs (e.g. vessel endothelium, endocardial cells and scavenger ECs) and RBCs. The antibody can be used with immunohistochemistry, IFAT and on Western blots. It appears that the epitope recognised by the antibody is associated with the ISAV cellular receptor. Besides being a tool to identify ECs in situ, it could be useful in further studies of the pathogenicity of ISA. Finally, the detection of an epitope shared by ECs and RBCs agrees with recent findings that these cells share a common origin, thus the MAb can potentially be used to study the ontogeny of these cells in Atlantic salmon. © 2013 Anatomical Society.

Antibody-drug conjugate targeting CD46 eliminates multiple myeloma cells.

PubMed

Sherbenou, Daniel W; Aftab, Blake T; Su, Yang; Behrens, Christopher R; Wiita, Arun; Logan, Aaron C; Acosta-Alvear, Diego; Hann, Byron C; Walter, Peter; Shuman, Marc A; Wu, Xiaobo; Atkinson, John P; Wolf, Jeffrey L; Martin, Thomas G; Liu, Bin

2016-12-01

Multiple myeloma is incurable by standard approaches because of inevitable relapse and development of treatment resistance in all patients. In our prior work, we identified a panel of macropinocytosing human monoclonal antibodies against CD46, a negative regulator of the innate immune system, and constructed antibody-drug conjugates (ADCs). In this report, we show that an anti-CD46 ADC (CD46-ADC) potently inhibited proliferation in myeloma cell lines with little effect on normal cells. CD46-ADC also potently eliminated myeloma growth in orthometastatic xenograft models. In primary myeloma cells derived from bone marrow aspirates, CD46-ADC induced apoptosis and cell death, but did not affect the viability of nontumor mononuclear cells. It is of clinical interest that the CD46 gene resides on chromosome 1q, which undergoes genomic amplification in the majority of relapsed myeloma patients. We found that the cell surface expression level of CD46 was markedly higher in patient myeloma cells with 1q gain than in those with normal 1q copy number. Thus, genomic amplification of CD46 may serve as a surrogate for target amplification that could allow patient stratification for tailored CD46-targeted therapy. Overall, these findings indicate that CD46 is a promising target for antibody-based treatment of multiple myeloma, especially in patients with gain of chromosome 1q.

Homogeneous plate based antibody internalization assay using pH sensor fluorescent dye.

PubMed

Nath, Nidhi; Godat, Becky; Zimprich, Chad; Dwight, Stephen J; Corona, Cesear; McDougall, Mark; Urh, Marjeta

2016-04-01

Receptor-mediated antibody internalization is a key mechanism underlying several anti-cancer antibody therapeutics. Delivering highly toxic drugs to cancer cells, as in the case of antibody drug conjugates (ADCs), efficient removal of surface receptors from cancer cells and changing the pharmacokinetics profile of the antibody drugs are some of key ways that internalization impacts the therapeutic efficacy of the antibodies. Over the years, several techniques have been used to study antibody internalization including radiolabels, fluorescent microscopy, flow cytometry and cellular toxicity assays. While these methods allow analysis of internalization, they have limitations including a multistep process and limited throughput and are generally endpoint assays. Here, we present a new homogeneous method that enables time and concentration dependent measurements of antibody internalization. The method uses a new hydrophilic and bright pH sensor dye (pHAb dye), which is not fluorescent at neutral pH but becomes highly fluorescent at acidic pH. For receptor mediated antibody internalization studies, antibodies against receptors are conjugated with the pHAb dye and incubated with the cells expressing the receptors. Upon binding to the receptor, the dyes conjugated to the antibody are not fluorescent because of the neutral pH of the media, but upon internalization and trafficking into endosomal and lysosomal vesicles the pH drops and dyes become fluorescent. The enabling attributes of the pHAb dyes are the hydrophilic nature to minimize antibody aggregation and bright fluorescence at acidic pH which allows development of simple plate based assays using a fluorescent reader. Using two different therapeutic antibodies--Trastuzumab (anti-HER2) and Cetuximab (anti-EGFR)--we show labeling with pHAb dye using amine and thiol chemistries and impact of chemistry and dye to antibody ration on internalization. We finally present two new approaches using the pHAb dye, which will be beneficial for screening a large number of antibody samples during early monoclonal development phase. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Fn3 proteins engineered to recognize tumor biomarker mesothelin internalize upon binding

PubMed Central

Sirois, Allison R.; Deny, Daniela A.; Baierl, Samantha R.; George, Katia S.

2018-01-01

Mesothelin is a cell surface protein that is overexpressed in numerous cancers, including breast, ovarian, lung, liver, and pancreatic tumors. Aberrant expression of mesothelin has been shown to promote tumor progression and metastasis through interaction with established tumor biomarker CA125. Therefore, molecules that specifically bind to mesothelin have potential therapeutic and diagnostic applications. However, no mesothelin-targeting molecules are currently approved for routine clinical use. While antibodies that target mesothelin are in development, some clinical applications may require a targeting molecule with an alternative protein fold. For example, non-antibody proteins are more suitable for molecular imaging and may facilitate diverse chemical conjugation strategies to create drug delivery complexes. In this work, we engineered variants of the fibronectin type III domain (Fn3) non-antibody protein scaffold to bind to mesothelin with high affinity, using directed evolution and yeast surface display. Lead engineered Fn3 variants were solubly produced and purified from bacterial culture at high yield. Upon specific binding to mesothelin on human cancer cell lines, the engineered Fn3 proteins internalized and co-localized to early endosomes. To our knowledge, this is the first report of non-antibody proteins engineered to bind mesothelin. The results validate that non-antibody proteins can be engineered to bind to tumor biomarker mesothelin, and encourage the continued development of engineered variants for applications such as targeted diagnostics and therapeutics. PMID:29738555

Enhanced activation of human T cell clones specific for virus-like particles expressing the HIV V3 loop in the presence of HIV V3 loop-specific polyclonal antibodies

PubMed Central

Peifang, S.; Pira, G. L.; Fenoglio, D.; Harris, S.; Costa, M. G.; Venturino, V.; Dessì, V.; Layton, G.; Laman, J.; Huisman, J. G.; Manca, F.

1994-01-01

Recombinant virus-like particles (VLP), formed by the yeast Ty p1 protein, carrying the HIV gp120 V3 loop on their surface (V3-VLP) have been tested in vitro for immunogenicity and antigenicity by using VLP p1-specific human CD4+ T cell lines and clones. VLP-specific human T cell lines and clones were generated from normal individuals, indicating that VLP-specific precursor cells present in the peripheral lymphocyte pool can be induced to expand clonally upon antigen challenge in vitro, in the absence of previous immunization. It was also shown that V3-specific polyclonal antibodies enhance V3-VLP-induced activation of VLP-specific T cell clones. Antibody-dependent potentiation has been shown previously in other antigen systems, and it depends on enhanced uptake of complexed antigen by Fc receptor-positive antigen-presenting cells. Since in this case antigen is internalized by presenting cells as a complex, it can be inferred that a similar event of antibody-mediated antigen uptake can take place with V3-specific B cells, resulting in presentation by the B cells of T helper epitopes derived from processing of the VLP p1 moiety. This suggests that T helper cells specific for the carrier VLP p1 protein can be activated to provide help to V3-specific B cells in the presence of the appropriate antigen construct. PMID:7915974

Paper diagnostic for instantaneous blood typing.

PubMed

Khan, Mohidus Samad; Thouas, George; Shen, Wei; Whyte, Gordon; Garnier, Gil

2010-05-15

Agglutinated blood transports differently onto paper than stable blood with well dispersed red cells. This difference was investigated to develop instantaneous blood typing tests using specific antibody-antigen interactions to trigger blood agglutination. Two series of experiments were performed. The first related the level of agglutination and the fluidic properties of blood on its transport in paper. Blood samples were mixed at different ratios with specific and nonspecific antibodies; a droplet of each mixture was deposited onto a filter paper strip, and the kinetics of wicking and red cell separation were measured. Agglutinated blood phase separated, with the red blood cells (RBC) forming a distinct spot upon contact with paper while the plasma wicked; in contrast, stable blood suspensions wicked uniformly. The second study analyzed the wicking and the chromatographic separation of droplets of blood deposited onto paper strips pretreated with specific and nonspecific antibodies. Drastic differences in transport occurred. Blood agglutinated by interaction with one of its specific antibodies phase separated, causing a chromatographic separation. The red cells wicked very little while the plasma wicked at a faster rate than the original blood sample. Blood agglutination and wicking in paper followed the concepts of colloids chemistry. The immunoglobin M antibodies agglutinated the red blood cells by polymer bridging, upon selective adsorption on the specific antigen at their surface. The transport kinetics was viscosity controlled, with the viscosity of red cells drastically increasing upon blood agglutination. Three arm prototypes were investigated for single-step blood typing.

A novel micro-emulsion and micelle assembling method to prepare DEC205 monoclonal antibody coupled cationic nanoliposomes for simulating exosomes to target dendritic cells.

PubMed

Li, Kexin; Chang, Shasha; Wang, Zhongyan; Zhao, Xiuli; Chen, Dawei

2015-08-01

Cationic biomimetic exosomes were prepared using a novel micro-emulsion and micelle assembling method by introducing DEC205 monoclonal antibody as specific ligand to target dendritic cells (DCs). The Box-Behnken experimental design was applied for optimization of nanoliposomes (NLip) and DEC205 monoclonal antibody was then conjugated on the surface of NLip (DEC205-NLip). NLip and DEC205-NLip respectively had an average size of 62.7 ± 6.33 nm and 81.64 ± 4.25 nm, zeta potential of +30.5 ± 2.3 mV and +19.8 ± 1.8 mV and encapsulation efficiency of 91.02 ± 3.1% and 93.10 ± 2.2%. In addition, the toxicity studies confirmed DEC205 monoclonal antibody could significantly reduce the cytotoxicity of the cationic lipid against DCs. And the cellular uptake experiment evaluated the significant targeting effect of the DEC205 monoclonal antibody on DC cells. In conclusion, the novel method presented here to prepare biomimetic exosomes was an efficient approach to develop antigen carriers for specific DCs targeting. Copyright © 2015 Elsevier B.V. All rights reserved.

Generation of a Canine Anti-EGFR (ErbB-1) Antibody for Passive Immunotherapy in Dog Cancer Patients

PubMed Central

Wang, Wei; Weichselbaumer, Marlene; Matz, Miroslawa; Mader, Alexander; Steinfellner, Willibald; Meitz, Sarah; Mechtcheriakova, Diana; Sobanov, Yuri; Willmann, Michael; Stockner, Thomas; Spillner, Edzard; Kunert, Renate; Jensen-Jarolim, Erika

2014-01-01

Passive immunotherapy with monoclonal antibodies represents a cornerstone of human anticancer therapies, but has not been established in veterinary medicine yet. As the tumor-associated antigen EGFR (ErbB-1) is highly conserved between humans and dogs, and considering the effectiveness of the anti-EGFR antibody cetuximab in human clinical oncology, we present here a “caninized” version of this antibody, can225IgG, for comparative oncology studies. Variable region genes of 225, the murine precursor of cetuximab, were fused with canine constant heavy gamma and kappa chain genes, respectively, and transfected into Chinese hamster ovary (CHO) DUKX-B11 cells. Of note, 480 clones were screened and the best clones were selected according to productivity and highest specificity in EGFR-coated ELISA. Upon purification with Protein G, the recombinant cetuximab-like canine IgG was tested for integrity, correct assembly, and functionality. Specific binding to the surface of EGFR-overexpressing cells was assessed by flow cytometry and immunofluorescence; moreover, binding to canine mammary tissue was demonstrated by immunohistochemistry. In cell viability and proliferation assays, incubation with can225IgG led to significant tumor cell growth inhibition. Moreover, this antibody mediated significant tumor cell killing via phagocytosis in vitro. We thus present here, for the first time, the generation of a canine IgG antibody and its hypothetical structure. On the basis of its cetuximab-like binding site, on the one hand, and the expression of a 91% homologous EGFR molecule in canine cancer, on the other hand, this antibody may be a promising research compound to establish passive immunotherapy in dog patients with cancer. PMID:24755200

Myeloma-Derived Light Chain Paired with a Diagnostic Monoclonal Antibody Hinders Immunoassay Performance.

PubMed

Tu, Bailin; Tieman, Bryan; Moore, Jeffrey; Pan, You; Muerhoff, A Scott

2017-06-01

Monoclonal antibodies are widely used as the capture and detection reagents in diagnostic immunoassays. In the past, myeloma fusion partners expressing endogenous heavy and/or light chains were often used to generate hybridoma cell lines. As a result, mixed populations of antibodies were produced that can cause inaccurate test results, poor antibody stability, and significant lot-to-lot variability. We describe one such scenario where the P3U1 (P3X63Ag8U.1) myeloma fusion partner was used in the generation of a hybridoma producing protein induced vitamin K absence/antagonist-II (PIVKA II) antibody. The hybridoma produces three subpopulations of immunoglobulin as determined by ion exchange (IEx) chromatography that exhibit varying degrees of immunoreactivity (0%, 50%, or 100%) to the target antigen as determined by Surface Plasmon Resonance. To produce an antibody with the highest possible sensitivity and specificity, the antigen-specific heavy and light chain variable domains (VH and VL) were cloned from the hybridoma and tethered to murine IgG1 and kappa scaffolds. The resulting recombinant antibody was expressed in Chinese hamster ovary cells and is compatible for use in a diagnostic immunoassay.

Selection of Single Domain Antibodies from Immune Libraries Displayed on the Surface of E. coli Cells with Two β-Domains of Opposite Topologies

PubMed Central

Martínez-Arteaga, Rocio; Ruano-Gallego, David; Fraile, Sofía; Margolles, Yago; Teira, Xema; Gutierrez, Carlos; Bodelón, Gustavo; Fernández, Luis Ángel

2013-01-01

Screening of antibody (Ab) libraries by direct display on the surface of E. coli cells is hampered by the presence of the outer membrane (OM). In this work we demonstrate that the native β-domains of EhaA autotransporter and intimin, two proteins from enterohemorrhagic E. coli O157:H7 (EHEC) with opposite topologies in the OM, are effective systems for the display of immune libraries of single domain Abs (sdAbs) from camelids (nanobodies or VHH) on the surface of E. coli K-12 cells and for the selection of high affinity sdAbs using magnetic cell sorting (MACS). We analyzed the capacity of EhaA and intimin β-domains to display individual sdAbs and sdAb libraries obtained after immunization with the extracellular domain of the translocated intimin receptor from EHEC (TirMEHEC). We demonstrated that both systems displayed functional sdAbs on the surface of E. coli cells with little proteolysis and cellular toxicity, although E. coli cells displaying sdAbs with the β-domain of intimin showed higher antigen-binding capacity. Both E. coli display libraries were screened for TirMEHEC binding clones by MACS. High affinity binders were selected by both display systems, although more efficiently with the intimin β-domain. The specificity of the selected clones against TirMEHEC was demonstrated by flow cytometry of E. coli cells, along with ELISA and surface plasmon resonance with purified sdAbs. Finally, we employed the E. coli cell display systems to provide an estimation of the affinity of the selected sdAb by flow cytometry analysis under equilibrium conditions. PMID:24086454

Avidin-conjugated calcium phosphate nanoparticles as a modular targeting system for the attachment of biotinylated molecules in vitro and in vivo.

PubMed

van der Meer, Selina Beatrice; Knuschke, Torben; Frede, Annika; Schulze, Nina; Westendorf, Astrid M; Epple, Matthias

2017-07-15

Avidin was covalently conjugated to the surface of calcium phosphate nanoparticles, coated with a thin silica shell and terminated by sulfhydryl groups (diameter of the solid core about 50nm), with a bifunctional crosslinker connecting the amino groups of avidin to the sulfhydryl group on the nanoparticle surface. This led to a versatile nanoparticle system where all kinds of biotinylated (bio-)molecules can be easily attached to the surface by the non-covalent avidin-biotin-complex formation. It also permits the attachment of different biomolecules on the same nanoparticle (heteroavidity), creating a modular system for specific applications in medicine and biology. The variability of the binding to the nanoparticle surface of the was demonstrated with various biotinylated molecules, i.e. fluorescent dyes and antibodies. The accessibility of the conjugated avidin was demonstrated by a fluorescence-quenching assay. About 2.6 binding sites for biotin were accessible on each avidin tetramer. Together with a number of about 240 avidin tetramer units per nanoparticle, this offers about 600 binding sites for biotin on each nanoparticle. The uptake of fluorescently labelled avidin-conjugated calcium phosphate nanoparticles by HeLa cells showed the co-localization of fluorescent avidin and fluorescent biotin, indicating the stability of the complex under cell culture conditions. CD11c-antibody functionalized nanoparticles specifically targeted antigen-presenting immune cells (dendritic cells; DCs) in vitro and in vivo (mice) with high efficiency. Calcium phosphate nanoparticles have turned out to be very useful transporters for biomolecules into cells, both in vitro and in vivo. However, their covalent surface functionalization with antibodies, fluorescent dyes, or proteins requires a separate chemical synthesis for each kind of surface molecule. We have therefore developed avidin-terminated calcium phosphate nanoparticles to which all kinds of biotinylated molecules can be easily attached, also as a mixture of two or more molecules. This non-covalent bond is stable both in cell culture and after injection into mice in vivo. Thus, we have created a highly versatile system for many applications, from the delivery of biomolecules over the targeting of cells and tissue to in vivo imaging. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Antibody to human α-fetoprotein inhibits cell growth of human hepatocellular carcinoma cells by resuscitating the PTEN molecule: in vitro experiments.

PubMed

Ohkawa, Kiyoshi; Asakura, Tadashi; Tsukada, Yutaka; Matsuura, Tomokazu

2017-06-01

It has been proposed that α-fetoprotein (AFP) is a new member of the intracellular signaling molecule family of the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway via interaction with the phosphatase and tensin homolog (PTEN). In this study, the effects of anti-human AFP antibody on the functions of PTEN were examined using an AFP-producing human hepatoma cell line. The antibody caused significant inhibition of cell growth, compared to a normal IgG control, with the accumulation of intracellular immune complexes followed by significant reduction of cytosolic functional AFP. Decrease in the amount of AKT phosphorylated on serine (S) 473 indicated that PI3K/AKT signaling was suppressed in the cells. S380-phosphorylated PTEN increased markedly by the second day after antibody treatment, with slight but significant increase in the PTEN protein level. Since phosphorylation at S380 is critical for PTEN stability, the increase in S380-phosphorylated PTEN indicated maintenance of the number of PTEN molecules and the related potential to control PI3K/AKT signaling. p53 protein (P53) significantly, but slightly increased during antibody treatment, because PTEN expression increased the stability and function of P53 via both molecular interactions. P53 phosphorylated at S20 or at S392 dramatically increased, suggesting an increase in the stability, accumulation and activation of P53. Glucose transporter 1 (GLUT1) increased immediately after antibody treatment, pointing to a deficiency of glucose in the cells. Immunofluorescence cytology revealed that antibody-treatment re-distributed GLUT1 molecules throughout the cytoplasm with a reduction of their patchy localization on the cell surface. This suggested that translocation of GLUT1 depends on the PI3K/AKT pathway, in particular on PTEN expression. Antibody therapy targeted at AFP-producing tumor cells showed an inhibitory effect on the PI3K/AKT pathway via the liberation, restoration and functional stabilization of PTEN. PTEN simultaneously induced both P53 activation and intracellular translocation of GLUT1, since these are closely associated with PTEN.

Novel Epstein-Barr virus-like particles incorporating gH/gL-EBNA1 or gB-LMP2 induce high neutralizing antibody titers and EBV-specific T-cell responses in immunized mice.

PubMed

Perez, Elizabeth M; Foley, Joslyn; Tison, Timelia; Silva, Rute; Ogembo, Javier Gordon

2017-03-21

Previous Epstein-Barr virus (EBV) prophylactic vaccines based on the major surface glycoprotein gp350/220 as an immunogen have failed to block viral infection in humans, suggesting a need to target other viral envelope glycoproteins. In this study, we reasoned that incorporating gH/gL or gB, critical glycoproteins for viral fusion and entry, on the surface of a virus-like particle (VLP) would be more immunogenic than gp350/220 for generating effective neutralizing antibodies to prevent viral infection of both epithelial and B cell lines. To boost the humoral response and trigger cell-mediated immunity, EBV nuclear antigen 1 (EBNA1) and latent membrane protein 2 (LMP2), intracellular latency proteins expressed in all EBV-infected cells, were also included as critical components of the polyvalent EBV VLP. gH/gL-EBNA1 and gB-LMP2 VLPs were efficiently produced in Chinese hamster ovary cells, an FDA-approved vehicle for mass-production of biologics. Immunization with gH/gL-EBNA1 and gB-LMP2 VLPs without adjuvant generated both high neutralizing antibody titers in vitro and EBV-specific T-cell responses in BALB/c mice. These data demonstrate that will be invaluable not only in preventing EBV infection, but importantly, in preventing and treating the 200,000 cases of EBV-associated cancers that occur globally every year.

Mechanistic understanding of the cysteine capping modifications of antibodies enables selective chemical engineering in live mammalian cells.

PubMed

Zhong, Xiaotian; He, Tao; Prashad, Amar S; Wang, Wenge; Cohen, Justin; Ferguson, Darren; Tam, Amy S; Sousa, Eric; Lin, Laura; Tchistiakova, Lioudmila; Gatto, Scott; D'Antona, Aaron; Luan, Yen-Tung; Ma, Weijun; Zollner, Richard; Zhou, Jing; Arve, Bo; Somers, Will; Kriz, Ronald

2017-04-20

Protein modifications by intricate cellular machineries often redesign the structure and function of existing proteins to impact biological networks. Disulfide bond formation between cysteine (Cys) pairs is one of the most common modifications found in extracellularly-destined proteins, key to maintaining protein structure. Unpaired surface cysteines on secreted mammalian proteins are also frequently found disulfide-bonded with free Cys or glutathione (GSH) in circulation or culture, the mechanism for which remains unknown. Here we report that these so-called Cys-capping modifications take place outside mammalian cells, not in the endoplasmic reticulum (ER) where oxidoreductase-mediated protein disulfide formation occurs. Unpaired surface cysteines of extracellularly-arrived proteins such as antibodies are uncapped upon secretion before undergoing disulfide exchange with cystine or oxidized GSH in culture medium. This observation has led to a feasible way to selectively modify the nucleophilic thiol side-chain of cell-surface or extracellular proteins in live mammalian cells, by applying electrophiles with a chemical handle directly into culture medium. These findings provide potentially an effective approach for improving therapeutic conjugates and probing biological systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Hacking into the granuloma: could antibody antibiotic conjugates be developed for TB?

PubMed

Ekins, Sean

2014-12-01

Alternatives to small molecule or vaccine approaches to treating tuberculosis are rarely discussed. Attacking Mycobacterium tuberculosis in the granuloma represents a challenge. It is proposed that the conjugation of small molecules onto a monoclonal antibody that recognizes macrophage or lymphocytes cell surface receptors, might be a way to target the bacteria in the granuloma. This antibody drug conjugate approach is currently being used in 2 FDA approved targeted cancer therapies. The pros and cons of this proposal for further research are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Rapid detection of Bacillus anthracis using monoclonal antibody functionalized QCM sensor.

PubMed

Hao, Rongzhang; Wang, Dianbing; Zhang, Xian'en; Zuo, Guomin; Wei, Hongping; Yang, Ruifu; Zhang, Zhiping; Cheng, Zhenxing; Guo, Yongchao; Cui, Zongqiang; Zhou, Yafeng

2009-01-01

Since the anthrax spore bioterrorism attacks in America in 2001, the early detection of Bacillus anthracis spores and vegetative cells has gained significant interest. At present, many polyclonal antibody-based quartz crystal microbalance (QCM) sensors have been developed to detect B. anthracis simulates. To achieve a simultaneous rapid detection of B. anthracis spores and vegetative cells, this paper presents a biosensor that utilizes an anti-B. anthracis monoclonal antibody designated to 8G3 (mAb 8G3, IgG) functionalized QCM sensor. Having compared four kinds of antibody immobilizations on Au surface, an optimized mAb 8G3 was immobilized onto the Au electrode with protein A on a mixed self-assembled monolayer (SAM) of 11-mercaptoundecanoic acid (11-MUA) and 6-mercaptohexan-1-ol (6-MHO) as adhesive layer. The detection of B. anthracis was investigated under three conditions: dip-and-dry, static addition and flow through procedure. The results indicated that the sensor yielded a distinct response to B. anthracis spores or vegetative cells but had no significant response to Bacillus thuringiensis species. The functionalized sensor recognized B. anthracis spores and vegetative cells specifically from its homophylic ones, and the limit of detection (LOD) reached 10(3)CFU or spores/ml of B. anthracis in less than 30 min. Cyclic voltammogram (CV) and scanning electronic microscopy (SEM) were performed to characterize the surface of the sensor in variable steps during the modification and after the detection. The mAb functionalized QCM biosensor will be helpful in the fabrication of a similar biosensor that may be available in anti-bioterrorism in the future.

Immune complexes formed following the binding of anti–platelet factor 4 (CXCL4) antibodies to CXCL4 stimulate human neutrophil activation and cell adhesion

PubMed Central

Xiao, Zhihua; Visentin, Gian P.; Dayananda, Kannayakanahalli M.

2008-01-01

We tested the possibility that immune complexes formed following platelet factor 4 (PF4/CXCL4) binding to anti-PF4 antibody can stimulate neutrophil activation, similar to previous reports with platelets. Monoclonal Abs against PF4 and IgG from a heparin-induced thrombocytopenia (HIT) patient were applied. We observed that although PF4 or anti-PF4 antibody alone did not alter neutrophil function, costimulation with both reagents resulted in approximately 3-fold increase in cell surface Mac-1 expression, enhanced cell adhesion via L-selectin and CD18 integrins, and degranulation of secondary and tertiary granules. The level of Mac-1 up-regulation peaked at an intermediate PF4 dose, suggesting that functional response varies with antigen-antibody stoichiometry. PF4 binding to neutrophils was blocked by chondroitinase ABC. Cell activation was inhibited by both chondroitinase ABC and anti-CD32/FcγRII blocking mAb, IV.3. Confocal microscopy demonstrated that immune complexes colocalize with CD32a. Studies with HIT IgG demonstrated that neutrophils could be activated in the absence of exogenous heparin. These data, together, show that leukocyte surface chondroitin sulfates promote neutrophil activation by enhancing immune-complex binding to CD32a. Studies with recombinant PF4 suggest a role for arginine 49 in stabilizing PF4-chondroitin binding. Neutrophils activated via this mechanism may contribute to thrombosis and inflammation in patients mounting an immune response to PF4-heparin. PMID:18539895

A Cancer‐reactive Human Monoclonal Antibody Derived from a Colonic Cancer Patient Treated with Local Immunotherapy

PubMed Central

Yagyu, Toshio; Monden, Takushi; Baba, Masashi; Tamaki, Yasuhiro; Takeda, Tsutomu; Kobayashi, Tetsuro; Shimano, Takashi; Tsuji, Yoshiyuki; Matsushita, Hirohisa; Osawa, Hisao; Murakami, Hiroki; Mori, Takesada

1993-01-01

A human monoclonal antibody, YJ‐37 (IgM) was generated through the fusion of human B lymphoblastoid cell line HO‐323 with the regional lymph node lymphocytes from a colonic cancer patient who was treated with a local immunotherapy. This antibody was purified and conjugated with biotin, after which direct immunohistochemical staining was performed. The results revealed that YJ‐37 selectively reacted with colonic cancer (7/19), gastric cancer (3/6), endometrial cancer (1/2) and colonic adenoma (7/13), but not with normal epithelia. Membrane immunofluorescence and FACS analysis also showed that YJ‐37 bound to tumor cell surfaces. Furthermore, the chemical structure of the antigen defined by YJ‐37 was analyzed by means of thin‐layer chromatography immunostaining and ELISA. The results indicated that YJ‐37 reacted with sialylated lacto‐series carbohydrate chains, which have been reported to accumulate in cancer cells. PMID:8449830

Limitations of a localized surface plasmon resonance sensor on Salmonella detection

USDA-ARS?s Scientific Manuscript database

We have designed a localized surface plasmon resonance (LSPR) biosensor to perform the whole cell detection of Salmonella using gold nanoparticls fabricated by oblique angle deposition technique. The LSPR sensor showed a plasmon peak shift due to the Salmonella antigen and anti-Salmonella antibody r...

Neuronal antibodies in pediatric epilepsy: Clinical features and long-term outcomes of a historical cohort not treated with immunotherapy.

PubMed

Wright, Sukhvir; Geerts, Ada T; Jol-van der Zijde, Cornelia Maria; Jacobson, Leslie; Lang, Bethan; Waters, Patrick; van Tol, Maarten J D; Stroink, Hans; Neuteboom, Rinze F; Brouwer, Oebele F; Vincent, Angela

2016-05-01

In autoimmune encephalitis the etiologic role of neuronal cell-surface antibodies is clear; patients diagnosed and treated early have better outcomes. Neuronal antibodies have also been described in patients with pediatric epilepsy without encephalitis. The aim was to assess whether antibody presence had any effect on long-term outcomes in these patients. Patients (n = 178) were recruited between 1988 and 1992 as part of the prospective Dutch Study of Epilepsy in Childhood; none received immunotherapy. Healthy age-matched bone-marrow donors served as controls (n = 112). All sera were tested for serum N-methyl-d-aspartate receptor (NMDAR), alpha amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor, leucine rich glioma inactivated 1, contactin associated protein like 2 (CASPR2), contactin-2, glutamic acid decarboxylase, and voltage gated potassium channel (VGKC)-complex antibodies by standard techniques. No cerebrospinal fluid (CSF) samples were available. Results were correlated with clinical data collected over 15 years. Seventeen patients (9.5%) were positive for VGKC complex (n = 3), NMDAR (n = 7), CASPR2 (n = 4), and contactin-2 (n = 3), compared to three (3/112; 2.6%) healthy controls (VGKC complex [n = 1], NMDAR [n = 2]; p = 0.03; Fisher's exact test). Titers were relatively low (≤1:100 for cell-surface antibodies), but 8 (47%) of the 17 positive samples bound to the surface of live hippocampal neurons consistent with a potential pathogenic antibody. Preexisting cognitive impairment was more frequent in antibody-positive patients (9/17 vs. 33/161; p = 0.01). Fourteen antibody-positive patients were treated with standard antiepileptic drugs (AEDs); three (17%) became intractable but this was not different from the 16 (10%) of 161 antibody-negative patients. In 96 patients with available follow-up samples at 6 and/or 12 months, 6 of 7 positive antibodies had disappeared and, conversely, antibodies had appeared for the first time in a further 7 patients. Neuronal antibodies were found at low levels in 9.5% of patients with new-onset pediatric epilepsy but did not necessarily persist over time, and the development of antibodies de novo in later samples suggests they could be due to a secondary response to neuronal damage or inflammation. Moreover, as the response to standard AEDs and the long-term outcome did not differ from those of antibody-negative pediatric patients, these findings suggest that routine neuronal antibody testing is unlikely to be helpful in pediatric epilepsy. However, the higher incidence of preexisting cognitive problems in the antibody-positive group, the CASPR2 and contactin-2 antibodies in 7 of 17 patients, and the binding of 8 of 17 of serum samples to live hippocampal neurons suggest that neuronal antibodies, even if secondary, could contribute to the comorbidities of pediatric epilepsy. © 2016 The Authors. Epilepsia published by Wiley Periodicals, Inc. on behalf of International League Against Epilepsy.

Immune response and histology of humoral rejection in kidney transplantation.

PubMed

González-Molina, Miguel; Ruiz-Esteban, Pedro; Caballero, Abelardo; Burgos, Dolores; Cabello, Mercedes; Leon, Miriam; Fuentes, Laura; Hernandez, Domingo

2016-01-01

The adaptive immune response forms the basis of allograft rejection. Its weapons are direct cellular cytotoxicity, identified from the beginning of organ transplantation, and/or antibodies, limited to hyperacute rejection by preformed antibodies and not as an allogenic response. This resulted in allogenic response being thought for decades to have just a cellular origin. But the experimental studies by Gorer demonstrating tissue damage in allografts due to antibodies secreted by B lymphocytes activated against polymorphic molecules were disregarded. The special coexistence of binding and unbinding between antibodies and antigens of the endothelial cell membranes has been the cause of the delay in demonstrating the humoral allogenic response. The endothelium, the target tissue of antibodies, has a high turnover, and antigen-antibody binding is non-covalent. If endothelial cells are attacked by the humoral response, immunoglobulins are rapidly removed from their surface by shedding and/or internalization, as well as degrading the components of the complement system by the action of MCP, DAF and CD59. Thus, the presence of complement proteins in the membrane of endothelial cells is transient. In fact, the acute form of antibody-mediated rejection was not demonstrated until C4d complement fragment deposition was identified, which is the only component that binds covalently to endothelial cells. This review examines the relationship between humoral immune response and the types of acute and chronic histological lesion shown on biopsy of the transplanted organ. Copyright © 2016 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.

Amino-Terminal β-Amyloid Antibody Blocks β-Amyloid-Mediated Inhibition of the High-Affinity Choline Transporter CHT.

PubMed

Cuddy, Leah K; Seah, Claudia; Pasternak, Stephen H; Rylett, R Jane

2017-01-01

Alzheimer's disease (AD) is a common age-related neurodegenerative disorder that is characterized by progressive cognitive decline. The deficits in cognition and attentional processing that are observed clinically in AD are linked to impaired function of cholinergic neurons that release the neurotransmitter acetylcholine (ACh). The high-affinity choline transporter (CHT) is present at the presynaptic cholinergic nerve terminal and is responsible for the reuptake of choline produced by hydrolysis of ACh following its release. Disruption of CHT function leads to decreased choline uptake and ACh synthesis, leading to impaired cholinergic neurotransmission. We report here that cell-derived β-amyloid peptides (Aβ) decrease choline uptake activity and cell surface CHT protein levels in SH-SY5Y neural cells. Moreover, we make the novel observation that the amount of CHT protein localizing to early endosomes and lysosomes is decreased significantly in cells that have been treated with cell culture medium that contains Aβ peptides released from neural cells. The Aβ-mediated loss of CHT proteins from lysosomes is prevented by blocking lysosomal degradation of CHT with the lysosome inhibitor bafilomycin A1 (BafA 1 ). BafA 1 also attenuated the Aβ-mediated decrease in CHT cell surface expression. Interestingly, however, lysosome inhibition did not block the effect of Aβ on CHT activity. Importantly, neutralizing Aβ using an anti-Aβ antibody directed at the N-terminal amino acids 1-16 of Aβ, but not by an antibody directed at the mid-region amino acids 22-35 of Aβ, attenuates the effect of Aβ on CHT activity and trafficking. This indicates that a specific N-terminal Aβ epitope, or specific conformation of soluble Aβ, may impair CHT activity. Therefore, Aβ immunotherapy may be a more effective therapeutic strategy for slowing the progression of cognitive decline in AD than therapies designed to promote CHT cell surface levels.

Construction of carbon nanotube based nanoarchitectures for selective impedimetric detection of cancer cells in whole blood.

PubMed

Liu, Yang; Zhu, Fanjiao; Dan, Wangxia; Fu, Yu; Liu, Shaoqin

2014-10-21

A carbon nanotube (CNT) based nanoarchitecture is developed for rapid, sensitive and specific detection of cancer cells by using real time electrical impedance sensing. The sensor is constructed with carbon nanotube (CNT) multilayers and EpCAM (epithelial cell adhesion molecule) antibodies, which are assembled on an indium tin oxide (ITO) electrode surface. The binding of tumor cells to EpCAM antibodies causes increase of the electron-transfer resistance. The electrochemical impedance of the prepared biosensors is linear with the logarithm of concentration of the liver cancer cell line (HepG2) within the concentration range of 10 to 10(5) cells per mL. The detection limit for HepG2 cells is 5 cells per mL. The proposed impedimetric sensing devices allow for sensitive and specific detection of cancer cells in whole-blood samples without any sample pretreatment steps.

B Cells Are Multifunctional Players in Multiple Sclerosis Pathogenesis: Insights from Therapeutic Interventions

PubMed Central

Claes, Nele; Fraussen, Judith; Stinissen, Piet; Hupperts, Raymond; Somers, Veerle

2015-01-01

Multiple sclerosis (MS) is a severe disease of the central nervous system (CNS) characterized by autoimmune inflammation and neurodegeneration. Historically, damage to the CNS was thought to be mediated predominantly by activated pro-inflammatory T cells. B cell involvement in the pathogenesis of MS was solely attributed to autoantibody production. The first clues for the involvement of antibody-independent B cell functions in MS pathology came from positive results in clinical trials of the B cell-depleting treatment rituximab in patients with relapsing-remitting (RR) MS. The survival of antibody-secreting plasma cells and decrease in T cell numbers indicated the importance of other B cell functions in MS such as antigen presentation, costimulation, and cytokine production. Rituximab provided us with an example of how clinical trials can lead to new research opportunities concerning B cell biology. Moreover, analysis of the antibody-independent B cell functions in MS has gained interest since these trials. Limited information is present on the effects of current immunomodulatory therapies on B cell functions, although effects of both first-line (interferon, glatiramer acetate, dimethyl fumarate, and teriflunomide), second-line (fingolimod, natalizumab), and even third-line (monoclonal antibody therapies) treatments on B cell subtype distribution, expression of functional surface markers, and secretion of different cytokines by B cells have been studied to some extent. In this review, we summarize the effects of different MS-related treatments on B cell functions that have been described up to now in order to find new research opportunities and contribute to the understanding of the pathogenesis of MS. PMID:26734009

Regulated internalization of caveolae

PubMed Central

1994-01-01

Caveolae are specialized invaginations of the plasma membrane which have been proposed to play a role in diverse cellular processes such as endocytosis and signal transduction. We have developed an assay to determine the fraction of internal versus plasma membrane caveolae. The GPI-anchored protein, alkaline phosphatase, was clustered in caveolae after antibody-induced crosslinking at low temperature and then, after various treatments, the relative amount of alkaline phosphatase on the cell surface was determined. Using this assay we were able to show a time- and temperature-dependent decrease in cell-surface alkaline phosphatase activity which was dependent on antibody-induced clustering. The decrease in cell surface alkaline phosphatase activity was greatly accelerated by the phosphatase inhibitor, okadaic acid, but not by a protein kinase C activator. Internalization of clustered alkaline phosphatase in the presence or absence of okadaic acid was blocked by cytochalasin D and by the kinase inhibitor staurosporine. Electron microscopy confirmed that okadaic acid induced removal of caveolae from the cell surface. In the presence of hypertonic medium this was followed by the redistribution of groups of caveolae to the center of the cell close to the microtubule-organizing center. This process was reversible, blocked by cytochalasin D, and the centralization of the caveolar clusters was shown to be dependent on an intact microtubule network. Although the exact mechanism of internalization remains unknown, the results show that caveolae are dynamic structures which can be internalized into the cell. This process may be regulated by kinase activity and require an intact actin network. PMID:7962085

Signalling through NK1.1 triggers NK cells to die but induces NK T cells to produce interleukin-4.

PubMed

Asea, A; Stein-Streilein, J

1998-02-01

In vivo inoculation of specific antibody is an accepted protocol for elimination of specific cell populations. Except for anti-CD3 and anti-CD4, it is not known if the depleted cells are eliminated by signalling through the target molecule or through a more non-specific mechanism. C57BL/6 mice were inoculated with anti-natural killer (NK1.1) monoclonal antibody (mAb). Thereafter spleen cells were harvested, stained for both surface and intracellular markers, and analysed by flow cytometry. As early as 2 hr post inoculation, NK cells were signalled to become apoptotic while signalling through the NK1.1 molecule activated NK1.1+ T-cell receptor (TCR)+ (NK T) cells to increase in number, and produce interleukin-4 (IL-4). Anti NK1.1 mAb was less efficient at signalling apoptosis in NK cells when NK T-cell deficient [beta 2-microglobulin beta 2m-deficient] mice were used compared with wild type mice. Efficient apoptotic signalling was restored when beta 2m-deficient mice were reconstituted with NK T cells. NK-specific antibody best signals the apoptotic process in susceptible NK cells when resistant NK T cells are present, activated, and secrete IL-4.

Bispecific small molecule-antibody conjugate targeting prostate cancer.

PubMed

Kim, Chan Hyuk; Axup, Jun Y; Lawson, Brian R; Yun, Hwayoung; Tardif, Virginie; Choi, Sei Hyun; Zhou, Quan; Dubrovska, Anna; Biroc, Sandra L; Marsden, Robin; Pinstaff, Jason; Smider, Vaughn V; Schultz, Peter G

2013-10-29

Bispecific antibodies, which simultaneously target CD3 on T cells and tumor-associated antigens to recruit cytotoxic T cells to cancer cells, are a promising new approach to the treatment of hormone-refractory prostate cancer. Here we report a site-specific, semisynthetic method for the production of bispecific antibody-like therapeutics in which a derivative of the prostate-specific membrane antigen-binding small molecule DUPA was selectively conjugated to a mutant αCD3 Fab containing the unnatural amino acid, p-acetylphenylalanine, at a defined site. Homogeneous conjugates were generated in excellent yields and had good solubility. The efficacy of the conjugate was optimized by modifying the linker structure, relative binding orientation, and stoichiometry of the ligand. The optimized conjugate showed potent and selective in vitro activity (EC50 ~ 100 pM), good serum half-life, and potent in vivo activity in prophylactic and treatment xenograft mouse models. This semisynthetic approach is likely to be applicable to the generation of additional bispecific agents using drug-like ligands selective for other cell-surface receptors.

Generation of monoclonal antibodies specific for cell surface molecules expressed on early mouse endoderm.

PubMed

Gadue, Paul; Gouon-Evans, Valerie; Cheng, Xin; Wandzioch, Ewa; Zaret, Kenneth S; Grompe, Markus; Streeter, Philip R; Keller, Gordon M

2009-09-01

The development of functional cell populations such as hepatocytes and pancreatic beta cells from embryonic stem cell (ESC) is dependent on the efficient induction of definitive endoderm early in the differentiation process. To monitor definitive endoderm formation in mouse ESC differentiation cultures in a quantitative fashion, we generated a reporter cell line that expresses human CD25 from the Foxa3 locus and human CD4 from the Foxa2 locus. Induction of these reporter ESCs with high concentrations of activin A led to the development of a CD25-Foxa3+CD4-Foxa2+ population within 4-5 days of culture. Isolation and characterization of this population showed that it consists predominantly of definitive endoderm that is able to undergo hepatic specification under the appropriate conditions. To develop reagents that can be used for studies on endoderm development from unmanipulated ESCs, from induced pluripotent stem cells, and from the mouse embryo, we generated monoclonal antibodies against the CD25-Foxa3+CD4-Foxa2+ population. With this approach, we identified two antibodies that react specifically with endoderm from ESC cultures and from the early embryo. The specificity of these antibodies enables one to quantitatively monitor endoderm development in ESC differentiation cultures, to study endoderm formation in the embryo, and to isolate pure populations of culture- or embryo-derived endodermal cells.

Fatal winter dysentery with severe anemia in an adult cow.

PubMed

Natsuaki, Sumiko; Goto, Keiichi; Nakamura, Kikuyasu; Yamada, Manabu; Ueo, Hiroshi; Komori, Toshihiro; Shirakawa, Hitomi; Uchinuno, Yukinori

2007-09-01

An adult dairy cow fatally affected with winter dysentery was investigated pathologically and virologically. The cow had severe anemia and diarrhea with massive blood. Pathologically, the loss of surface epithelial cells and necrosis of crypt epithelial cells in the large intestine were observed. Bovine coronavirus (BCV) antigen was observed in necrotic crypt epithelial cells of the large intestine. Virus particles were found in the necrotic epithelial cells of the large intestine. Virologically, BCV was isolated from the feces of the dead cow. The dead cow had no serum antibody against BCV although the co-habitants did. These suggest that severe infection of BCV in the cow without the BCV antibody accompanied by severe hemorrhagic anemia resulted in the cow's death.

Structural analysis of B-cell epitopes in antibody:protein complexes

PubMed Central

Kringelum, Jens Vindahl; Nielsen, Morten; Padkjær, Søren Berg; Lund, Ole

2012-01-01

The binding of antigens to antibodies is one of the key events in an immune response against foreign molecules and is a critical element of several biomedical applications including vaccines and immunotherapeutics. For development of such applications, the identification of antibody binding sites (B-cell epitopes) is essential. However experimental epitope mapping is highly cost-intensive and computer-aided methods do in general have moderate performance. One major reason for this moderate performance is an incomplete understanding of what characterizes an epitope. To fill this gap, we here developed a novel framework for comparing and superimposing B-cell epitopes and applied it on a dataset of 107 non-similar antigen:antibody structures extracted from the PDB database. With the presented framework, we were able to describe the general B-cell epitope as a flat, oblong, oval shaped volume consisting of predominantly hydrophobic amino acids in the center flanked by charged residues. The average epitope was found to be made up of ~15 residues with one linear stretch of 5 or more residues constituting more than half of the epitope size. Furthermore, the epitope area is predominantly constrained to a plane above the antibody tip, in which the epitope is orientated in a −30 to 60 degree angle relative to the light to heavy chain antibody direction. Contrary to previously findings, we did not find a significant deviation between the amino acid composition in epitopes and the composition of equally exposed parts of the antigen surface. Our results, in combination with previously findings, give a detailed picture of the B-cell epitope that may be used in development of improved B-cell prediction methods. PMID:22784991

Regression of devil facial tumour disease following immunotherapy in immunised Tasmanian devils

PubMed Central

Tovar, Cesar; Pye, Ruth J.; Kreiss, Alexandre; Cheng, Yuanyuan; Brown, Gabriella K.; Darby, Jocelyn; Malley, Roslyn C.; Siddle, Hannah V. T.; Skjødt, Karsten; Kaufman, Jim; Silva, Anabel; Baz Morelli, Adriana; Papenfuss, Anthony T.; Corcoran, Lynn M.; Murphy, James M.; Pearse, Martin J.; Belov, Katherine; Lyons, A. Bruce; Woods, Gregory M.

2017-01-01

Devil facial tumour disease (DFTD) is a transmissible cancer devastating the Tasmanian devil (Sarcophilus harrisii) population. The cancer cell is the ‘infectious’ agent transmitted as an allograft by biting. Animals usually die within a few months with no evidence of antibody or immune cell responses against the DFTD allograft. This lack of anti-tumour immunity is attributed to an absence of cell surface major histocompatibility complex (MHC)-I molecule expression. While the endangerment of the devil population precludes experimentation on large experimental groups, those examined in our study indicated that immunisation and immunotherapy with DFTD cells expressing surface MHC-I corresponded with effective anti-tumour responses. Tumour engraftment did not occur in one of the five immunised Tasmanian devils, and regression followed therapy of experimentally induced DFTD tumours in three Tasmanian devils. Regression correlated with immune cell infiltration and antibody responses against DFTD cells. These data support the concept that immunisation of devils with DFTD cancer cells can successfully induce humoral responses against DFTD and trigger immune-mediated regression of established tumours. Our findings support the feasibility of a protective DFTD vaccine and ultimately the preservation of the species. PMID:28276463

Cloning and Characterization of the Mouse Hepatitis Virus Receptor

DTIC Science & Technology

1991-02-11

materials. Viruses may also adhere to cell surfaces non-specifically through electrostatic interactions (Tardieu et al., 1982). Virus particles might be... viruses can utilize more than one type of receptor and that specific virus receptors may be present in low numbers on the cell surface or may be labile...known example of this type of interaction is the enhancement of virus infection by antibodies, which has been demonstrated for several viruses

Analysis of peroxidase-negative acute unclassifiable leukemias by monoclonal antibodies. 1. Acute myelogenous leukemia and acute myelomonocytic leukemia.

PubMed

Imamura, N; Tanaka, R; Kajihara, H; Kuramoto, A

1988-11-01

In this study, pretreatment peripheral and/or bone marrow blasts from 12 patients with acute unclassifiable leukemia (AUL) expressing the myeloid-related cell-surface antigen (CD 11) were isolated for further analysis. Despite a lack of myeloperoxidase (MPO) activity, 1 patient's blasts contained cytoplasmic Auer rods. The circulating blasts from another patient expressed MPO while maintaining the same surface phenotype during 20 months of clinical follow-up. In addition, the blasts from 3 cases demonstrated both myelomonocytic and monocyte-specific surface antigens, whereas the remaining 9 cases completely lacked any monocyte-specific antigen detectable by monoclonal antibodies, Mo2, My4 and Leu M3 (CD 14). The first case eventually was diagnosed as acute myelomonocytic leukemia and the second as acute myelogenous leukemia by means of immunophenotypic analysis using flow cytometry (FACS IV). In addition, the presence of MPO protein was identified in the cytoplasm of blast cells from 5 patients with AUL by means of a cytoplasmic immunofluorescence test using a monoclonal antibody (MA1). Our study indicates that non-T, non-B AUL expressing OKM1 (CD 11) antigens include acute leukemias which are unequivocally identifiable as being of either myeloid or myelomonocytic origin. However, further investigations, including immunophenotypic and cytoplasmic analysis, ultrastructural cytochemistry and gene analysis with molecular probes (tests applicable to normal myeloid cells), are necessary in order to determine the actual origin of blasts and to recognize the differentiation stages of the various types of leukemic cells from patients with undifferentiated forms of leukemia.

Biochemical properties of a keratan sulphate/chondroitin sulphate proteoglycan expressed in primate pluripotent stem cells*

PubMed Central

Cooper, Susan; Bennett, William; Andrade, Jessica; Reubinoff, Benjamin E; Thomson, James; Pera, Martin F

2002-01-01

We previously identified a pericellular matrix keratan sulphate/chondroitin sulphate proteoglycan present on the surface of human embryonal carcinoma stem cells, cells whose differentiation mimics early development. Antibodies reactive with various epitopes on this molecule define a cluster of differentiation markers for primate pluripotent stem cells. We describe the purification of a form of this molecule which is secreted or shed into the culture medium. Biochemical analysis of the secreted form of this molecule shows that the monomeric form, whilst containing keratan sulphate, resembles mucins in its structure and its modification with O-linked carbohydrate. Immunofluorescence and immunoblotting data show that monkey and human pluripotent stem cells react with antibodies directed against epitopes on either carbohydrate side chains or the protein core of the molecule. PMID:12033730

Real-time quantification of antibody-short interfering RNA conjugate in serum by antigen capture reverse transcription-polymerase chain reaction.

PubMed

Tan, Martha; Vernes, Jean-Michel; Chan, Joyce; Cuellar, Trinna L; Asundi, Aarati; Nelson, Christopher; Yip, Victor; Shen, Ben; Vandlen, Richard; Siebel, Christian; Meng, Y Gloria

2012-11-15

Short interfering RNA (siRNA) has therapeutic potential. However, efficient delivery is a formidable task. To facilitate delivery of siRNA into cells, we covalently conjugated siRNA to antibodies that bind to cell surface proteins and internalize. Understanding how these antibody-siRNA conjugates function in vivo requires pharmacokinetic analysis. Thus, we developed a simple real-time antigen capture reverse transcription-polymerase chain reaction (RT-PCR) assay to detect intact antibody-siRNA conjugates. Biotinylated antigen bound to streptavidin-coated PCR tubes was used to capture antibody-siRNA conjugate. The captured antibody-siRNA conjugate was then reverse-transcribed in the same tube, avoiding a sample transfer step. This reproducible assay had a wide standard curve range of 0.029 to 480ng/ml and could detect as low as 0.58ng/ml antibody-siRNA conjugates in mouse serum. The presence of unconjugated antibody that could be generated from siRNA degradation in vivo did not affect the assay as long as the total antibody concentration in the antigen capture step did not exceed 480ng/ml. Using this assay, we observed a more rapid decrease in serum antibody-siRNA conjugate concentrations than the total antibody concentrations in mice dosed with antibody-siRNA conjugates, suggesting loss of siRNA from the antibody. This assay is useful for optimizing antibody-siRNA and likely aptamer-siRNA conjugates to improve pharmacokinetics and aid siRNA delivery. Copyright © 2012 Elsevier Inc. All rights reserved.

Effects of spaceflight on levels and activity of immune cells

NASA Technical Reports Server (NTRS)

Sonnenfeld, Gerald; Berry, Wallace D.; Mandel, Adrian D.; Konstantinova, Irena V.; Taylor, Gerald R.

1990-01-01

Experiments were carried out on cells from rats that had been flown on Soviet Biosputnik Cosmos 1887 to explore the effects of speceflight on immune responses. Rat bone marrow cells were examined for their response to colony stimulating factor-M. Rat spleen and bone marrow cells were stained with antibodies directed against cell surface antigenic markers. The results of the studies indicate that bone marrow cells from flown rats showed a decreased response to colony stimulating factor. There was a higher percentage of spleen cells from flown rats staining positively for pan-T-cell, suppressor-T-cell, and interleukin-2 receptor cell surface antigens. A small increase in the percentage of cells staining positively for helper-T-cell antigens was also noted. In addition, a higher percentage of cells that appeared to be part of the myelogenous population of bone marrow cells from flown rats stained positively for surface immunoglobulin.

Role of the urokinase plasminogen activator receptor in mediating impaired efferocytosis of anti-SSA/Ro-bound apoptotic cardiocytes: Implications in the pathogenesis of congenital heart block.

PubMed

Briassouli, Paraskevi; Komissarova, Elena V; Clancy, Robert M; Buyon, Jill P

2010-08-06

Binding of maternal anti-Ro/La antibodies to cognate antigen expressed on apoptotic cardiocytes decreases clearance by healthy cardiocytes, which may contribute to the development of autoimmune associated congenital heart block and fatal cardiomyopathy. Given recent evidence implicating the urokinase plasminogen activator receptor (uPAR) as a "don't eat me" signal during efferocytosis, experiments addressed whether surface bound anti-Ro antibodies inhibit apoptotic cell removal via an effect on the expression/function of the urokinase-type plasminogen activator protease uPA/uPAR system. As assessed by flow cytometry and confocal microscopy, uPAR colocalizes and interacts with Ro60 on the surface of apoptotic human fetal cardiocytes. Blocking of uPAR enhances phagocytosis of apoptotic cardiocytes by healthy cardiocytes and reverses the anti-Ro60-dependent impaired clearance of apoptotic cardiocytes. Binding of anti-Ro60 antibodies to apoptotic cardiocytes results in increased uPAR expression, as well as enhanced uPA activity. The binding of anti-Ro60 did not alter other surface molecules involved in cell recognition (calreticulin, CD31, or CD47). These data suggest that increased uPAR expression and uPA activity induced by anti-Ro60 binding to the apoptotic fetal cardiocyte provide a molecular basis by which these antibodies inhibit efferocytosis and ultimately lead to scar of the fetal conduction system and working myocardium.

Impact of antibody subclass and disulfide isoform differences on the biological activity of CD200R and βklotho agonist antibodies.

PubMed

Grujic, Ognjen; Stevens, Jennitte; Chou, Robert Y-T; Weiszmann, Jennifer V; Sekirov, Laura; Thomson, Christy; Badh, Anita; Grauer, Stephanie; Chan, Brian; Graham, Kevin; Manchulenko, Kathy; Dillon, Thomas M; Li, Yang; Foltz, Ian N

2017-05-13

Agonism of cell surface receptors by monoclonal antibodies is dependent not only on its ability to bind the target, but also to deliver a biological signal through receptors to the cell. Immunoglobulin G2 antibodies (IgG2s) are made up of a mixture of distinct isoforms (IgG2-A, -B and A/B), which differ by the disulfide connectivity at the hinge region. When evaluating panels of agonistic antibodies against CD200 receptor (CD200R) or βklotho receptor (βklotho), we noticed striking activity differences of IgG1 or IgG2 antibodies with the same variable domains. For the CD200R antibody, the IgG2 antibody demonstrated higher activity than the IgG1 or IgG4 antibody. More significantly, for βklotho, agonist antibodies with higher biological activity as either IgG2 or IgG1 were identified. In both cases, ion exchange chromatography was able to isolate the bioactivity to the IgG2-B isoform from the IgG2 parental mixture. The subclass-related increase in agonist activity was not correlated with antibody aggregation or binding affinity, but was driven by enhanced avidity for the CD200R antibody. These results add to the growing body of evidence that show that conformational differences in the antibody hinge region can have a dramatic impact on the antibody activity and must be considered when screening and engineering therapeutic antibody candidates. The results also demonstrate that the IgG1 (IgG2-A like) or the IgG2-B form may provide the most active form of agonist antibodies for different antibodies and targets. Copyright © 2017 Elsevier Inc. All rights reserved.

Species specificity, surface exposure, protein expression, immunogenicity, and participation in biofilm formation of Porphyromonas gingivalis HmuY

PubMed Central

2010-01-01

Background Porphyromonas gingivalis is a major etiological agent of chronic periodontitis. The aim of this study was to examine the species specificity, surface exposure, protein expression, immunogenicity, and participation in biofilm formation of the P. gingivalis heme-binding protein HmuY. Results HmuY is a unique protein of P. gingivalis since only low amino-acid sequence homology has been found to proteins encoded in other species. It is exposed on the cell surface and highly abundant in the outer membrane of the cell, in outer-membrane vesicles, and is released into culture medium in a soluble form. The protein is produced constitutively at low levels in bacteria grown under high-iron/heme conditions and at higher levels in bacteria growing under the low-iron/heme conditions typical of dental plaque. HmuY is immunogenic and elicits high IgG antibody titers in rabbits. It is also engaged in homotypic biofilm formation by P. gingivalis. Anti-HmuY antibodies exhibit inhibitory activity against P. gingivalis growth and biofilm formation. Conclusions Here it is demonstrated that HmuY may play a significant role not only in heme acquisition, but also in biofilm accumulation on abiotic surfaces. The data also suggest that HmuY, as a surface-exposed protein, would be available for recognition by the immune response during chronic periodontitis and the production of anti-HmuY antibodies may inhibit biofilm formation. PMID:20438645

mAb C19 targets a novel surface marker for the isolation of human cardiac progenitor cells from human heart tissue and differentiated hESCs.

PubMed

Leung, Hau Wan; Moerkamp, Asja T; Padmanabhan, Jayanthi; Ng, Sze-Wai; Goumans, Marie-José; Choo, Andre

2015-05-01

Cardiac progenitor cells (CPCs) have been isolated from adult and developing hearts using an anti-mouse Sca-1 antibody. However, the absence of a human Sca-1 homologue has hampered the clinical application of the CPCs. Therefore, we generated novel monoclonal antibodies (mAbs) specifically raised against surface markers expressed by resident human CPCs. Here, we explored the suitability of one of these mAbs, mAb C19, for the identification, isolation and characterization of CPCs from fetal heart tissue and differentiating cultures of human embryonic stem cells (hESCs). Using whole-cell immunization, mAbs were raised against Sca-1+ CPCs and screened for reactivity to various CPC lines by flow cytometry. mAb C19 was found to be specific for Sca-1+ CPCs, with high cell surface binding capabilities. mAb C19 stained small stem-like cells in cardiac tissue sections. Moreover, during differentiation of hESCs towards cardiomyocytes, a transient population of cells with mAb C19 reactivity was identified and isolated using magnetic-activated cell sorting. Their cell fate was tracked and found to improve cardiomyocyte purity from hESC-derived cultures. mAb C19+ CPCs, from both hESC differentiation and fetal heart tissues, were maintained and expanded in culture, while retaining their CPC-like characteristics and their ability to further differentiate into cardiomyocytes by stimulation with TGFβ1. Finally, gene expression profiling of these mAb C19+ CPCs suggested a highly angiogenic nature, which was further validated by cell-based angiogenesis assays. mAb C19 is a new surface marker for the isolation of multipotent CPCs from both human heart tissues and differentiating hESCs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Surface heat shock protein 90 serves as a potential receptor for calcium oxalate crystal on apical membrane of renal tubular epithelial cells.

PubMed

Fong-Ngern, Kedsarin; Sueksakit, Kanyarat; Thongboonkerd, Visith

2016-07-01

Adhesion of calcium oxalate monohydrate (COM) crystals on renal tubular epithelial cells is a crucial step in kidney stone formation. Finding potential crystal receptors on the apical membrane of the cells may lead to a novel approach to prevent kidney stone disease. Our previous study identified a large number of crystal-binding proteins on the apical membrane of MDCK cells. However, their functional role as potential crystal receptors had not been validated. The present study aimed to address the potential role of heat shock protein 90 (HSP90) as a COM crystal receptor. The apical membrane was isolated from polarized MDCK cells by the peeling method and recovered proteins were incubated with COM crystals. Western blot analysis confirmed the presence of HSP90 in the apical membrane and the crystal-bound fraction. Immunofluorescence staining without permeabilization and laser-scanning confocal microscopy confirmed the surface HSP90 expression on the apical membrane of the intact cells. Crystal adhesion assay showed that blocking surface HSP90 by specific anti-HSP90 antibody and knockdown of HSP90 by small interfering RNA (siRNA) dramatically reduced crystal binding on the apical surface of MDCK cells (by approximately 1/2 and 2/3, respectively). Additionally, crystal internalization assay revealed the presence of HSP90 on the membrane of endocytic vesicle containing the internalized COM crystal. Moreover, pretreatment of MDCK cells with anti-HSP90 antibody significantly reduced crystal internalization (by approximately 1/3). Taken together, our data indicate that HSP90 serves as a potential receptor for COM crystals on the apical membrane of renal tubular epithelial cells and is involved in endocytosis/internalization of the crystals into the cells.

Structure of an HIV gp120 envelope glycoprotein in complex with the CD4 receptor and a neutralizing human antibody

PubMed Central

Kwong, Peter D.; Wyatt, Richard; Robinson, James; Sweet, Raymond W.; Sodroski, Joseph; Hendrickson, Wayne A.

2017-01-01

The entry of human immunodeficiency virus (HIV) into cells requires the sequential interaction of the viral exterior envelope glycoprotein, gp120, with the CD4 glycoprotein and a chemokine receptor on the cell surface. These interactions initiate a fusion of the viral and cellular membranes. Although gpl20 can elicit virus-neutralizing antibodies, HIV eludes the immune system. We have solved the X-ray crystal structure at 2.5 Å resolution of an HIV-1 gp120 core complexed with a two-domain fragment of human CD4 and an antigen-binding fragment of a neutralizing antibody that blocks chemokine-receptor binding. The structure reveals a cavity-laden CD4-gp120 interface, a conserved binding site for the chemokine receptor, evidence for a conformational change upon CD4 binding, the nature of a CD4-induced antibody epitope, and specific mechanisms for immune evasion. Our results provide a framework for understanding the complex biology of HIV entry into cells and should guide efforts to intervene. PMID:9641677

Histochemical in situ identification of bovine embryonic blood cells reveals differences to the adult haematopoietic system and suggests a close relationship between haematopoietic stem cells and primordial germ cells.

PubMed

Kritzenberger, Michaela; Wrobel, Karl-Heinz

2004-04-01

Cryostat sections of bovine embryos of exactly known age (obtained from artificial insemination), ranging from 32 to 60 days post-insemination, were treated with a wide range of antibodies directed against cell surface antigens or lineage-specific factors in order to demonstrate different types of fetal blood cells and their precursors. An antibody specific to bovine c-kit (bk-1) stained not only presumptive haematopoietic stem cells in the dorsal aorta and the embryonic liver, but also a subpopulation of putative primordial germ cells in the gonadal anlage, the latter being further characterised by a positive labelling with the lectins STA, WFA and WGA and a histochemical reaction for alkaline phosphatase. The antibody against CD 45, commonly regarded as a pan-leukocyte marker, reacted in the bovine embryo with different types of blood cells, as well as with presumptive vasculogenetic cells and a subpopulation of putative primordial germ cells. CD 61 immunoreaction proved to be a useful tool for demonstrating megakaryocytopoiesis in the embryonic liver, in addition to the lumen of blood vessels and the mesonephros. Staining with BM-2 was restricted to a single population of medium-sized, round to oval cells, forming small groups within the parenchymal strands of the liver. Characterised furthermore by a U-shaped nucleus, this BM-2-positive cell type apparently represents a developmental stage in the granulopoietic lineage. B-lymphocytopoiesis in the bovine liver was detected with antibodies directed against WC-4 and IgM, but not until day 58 post-insemination. Using antibodies to CD 14, no positive results could be obtained in embryonic tissues, although anti-CD 14-positive macrophages were easily recognised in lymph nodes of adult bovines. The antibody against CD 68, however, identified two populations of primitive macrophages in our samples. One population was located in parenchymal strands of the embryonic liver, probably acting as nursing cells for haematopoietic foci, and the other was observed intravasally in the sinusoids of the liver, most probably representing primitive Kupffer cells.

Identification of a Supramolecular Functional Architecture of Streptococcus mutans Adhesin P1 on the Bacterial Cell Surface*

PubMed Central

Heim, Kyle P.; Sullan, Ruby May A.; Crowley, Paula J.; El-Kirat-Chatel, Sofiane; Beaussart, Audrey; Tang, Wenxing; Besingi, Richard; Dufrene, Yves F.; Brady, L. Jeannine

2015-01-01

P1 (antigen I/II) is a sucrose-independent adhesin of Streptococcus mutans whose functional architecture on the cell surface is not fully understood. S. mutans cells subjected to mechanical extraction were significantly diminished in adherence to immobilized salivary agglutinin but remained immunoreactive and were readily aggregated by fluid-phase salivary agglutinin. Bacterial adherence was restored by incubation of postextracted cells with P1 fragments that contain each of the two known adhesive domains. In contrast to untreated cells, glutaraldehyde-treated bacteria gained reactivity with anti-C-terminal monoclonal antibodies (mAbs), whereas epitopes recognized by mAbs against other portions of the molecule were masked. Surface plasmon resonance experiments demonstrated the ability of apical and C-terminal fragments of P1 to interact. Binding of several different anti-P1 mAbs to unfixed cells triggered release of a C-terminal fragment from the bacterial surface, suggesting a novel mechanism of action of certain adherence-inhibiting antibodies. We also used atomic force microscopy-based single molecule force spectroscopy with tips bearing various mAbs to elucidate the spatial organization and orientation of P1 on living bacteria. The similar rupture lengths detected using mAbs against the head and C-terminal regions, which are widely separated in the tertiary structure, suggest a higher order architecture in which these domains are in close proximity on the cell surface. Taken together, our results suggest a supramolecular organization in which additional P1 polypeptides, including the C-terminal segment originally identified as antigen II, associate with covalently attached P1 to form the functional adhesive layer. PMID:25666624

Identification of a supramolecular functional architecture of Streptococcus mutans adhesin P1 on the bacterial cell surface.

PubMed

Heim, Kyle P; Sullan, Ruby May A; Crowley, Paula J; El-Kirat-Chatel, Sofiane; Beaussart, Audrey; Tang, Wenxing; Besingi, Richard; Dufrene, Yves F; Brady, L Jeannine

2015-04-03

P1 (antigen I/II) is a sucrose-independent adhesin of Streptococcus mutans whose functional architecture on the cell surface is not fully understood. S. mutans cells subjected to mechanical extraction were significantly diminished in adherence to immobilized salivary agglutinin but remained immunoreactive and were readily aggregated by fluid-phase salivary agglutinin. Bacterial adherence was restored by incubation of postextracted cells with P1 fragments that contain each of the two known adhesive domains. In contrast to untreated cells, glutaraldehyde-treated bacteria gained reactivity with anti-C-terminal monoclonal antibodies (mAbs), whereas epitopes recognized by mAbs against other portions of the molecule were masked. Surface plasmon resonance experiments demonstrated the ability of apical and C-terminal fragments of P1 to interact. Binding of several different anti-P1 mAbs to unfixed cells triggered release of a C-terminal fragment from the bacterial surface, suggesting a novel mechanism of action of certain adherence-inhibiting antibodies. We also used atomic force microscopy-based single molecule force spectroscopy with tips bearing various mAbs to elucidate the spatial organization and orientation of P1 on living bacteria. The similar rupture lengths detected using mAbs against the head and C-terminal regions, which are widely separated in the tertiary structure, suggest a higher order architecture in which these domains are in close proximity on the cell surface. Taken together, our results suggest a supramolecular organization in which additional P1 polypeptides, including the C-terminal segment originally identified as antigen II, associate with covalently attached P1 to form the functional adhesive layer. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

A direct immunoassay for detecting diatoms in groundwater as an indicator of the direct influence of surface water

USGS Publications Warehouse

Walker, C.E.; Schrock, R.M.; Reilly, T.J.; Baehr, A.L.

2005-01-01

Groundwater under the direct influence of surface water (GWUDISW) is of concern in communities where growing public demand on groundwater resources has resulted in increased withdrawals and hydraulic stress near surface water bodies. Under these conditions, contaminants such as methyl-tert butyl ether (MTBE) and biological materials have been detected in domestic wells. Other contaminants and pathogens associated with surface water are not routinely tested for in groundwater-supplied systems. To address the need for methods to easily identify potentially vulnerable supplies, a direct immunoassay for the quantitative detection of diatoms in raw water samples was developed as a measure of surface water influence on groundwater. Cell wall preparations from Nitzschia palea Ku??tzing, a freshwater diatom found throughout North America, were used to produce a polyclonal antibody that was applied in a direct enzyme-linked immunosorbent assay (ELISA) developed to detect the presence of N. palea cell wall components. The direct immunoassay allows detection at 500 cells L-1, a level similar to diatom concentrations observed in samples of groundwater collected near the test site. This investigation was the first attempt to utilize an ELISA as an indicator of surface water influence on groundwater. Further research is needed to develop more specific diatom-based monoclonal antibodies, determine cross-reactivity, and optimize sample processing and ELISA procedures for development of a standardized method. ?? Springer 2005.

A direct immunoassay for detecting diatoms in groundwater as an indicator of the direct influence of surface water

USGS Publications Warehouse

Walker, C.E.; Schrock, R.M.; Reilly, T.J.; Baehr, A.L.

2005-01-01

Groundwater under the direct influence of surface water (GWUDISW) is of concern in communities where growing public demand on groundwater resources has resulted in increased withdrawals and hydraulic stress near surface water bodies. Under these conditions, contaminants such as methyl-tert butyl ether (MTBE) and biological materials have been detected in domestic wells. Other contaminants and pathogens associated with surface water are not routinely tested for in groundwater-supplied systems. To address the need for methods to easily identify potentially vulnerable supplies, a direct immunoassay for the quantitative detection of diatoms in raw water samples was developed as a measure of surface water influence on groundwater. Cell wall preparations from Nitzschia palea Kützing, a freshwater diatom found throughout North America, were used to produce a polyclonal antibody that was applied in a direct enzyme-linked immunosorbent assay (ELISA) developed to detect the presence of N. palea cell wall components. The direct immunoassay allows detection at 500 cells L−1, a level similar to diatom concentrations observed in samples of groundwater collected near the test site. This investigation was the first attempt to utilize an ELISA as an indicator of surface water influence on groundwater. Further research is needed to develop more specific diatom-based monoclonal antibodies, determine cross-reactivity, and optimize sample processing and ELISA procedures for development of a standardized method.