Science.gov

Sample records for leukocyte fc gamma

  1. Altered polymorphonuclear leukocyte Fc gamma R expression contributes to decreased candicidal activity during intraabdominal sepsis

    SciTech Connect

    Simms, H.H.; D'Amico, R.; Monfils, P.; Burchard, K.W. )

    1991-03-01

    We investigated the effects of untreated intraabdominal sepsis on polymorphonuclear leukocyte (PMN) candicidal activity. Two groups of swine were studied. Group I (n=6) underwent sham laparotomy, group II (n=7) underwent cecal ligation and incision. Untreated intraabdominal sepsis resulted in a progressive decrease in PMN candicidal activity. Concomitant rosetting and phagocytosis assays demonstrated a decrease in both the attachment and phagocytosis of Candida albicans opsonized with both normal and septic swine serum by PMNs in group II. Iodine 125-labeled swine immunoglobulin G (IgG) and fluorescein isothioalanate (FITC)-labeled swine IgG were used to investigate Fc gamma receptor ligand interactions. Scatchard analyses demonstrated a progressive decline in both the binding affinity constant and number of IgG molecules bound per PMN. Stimulation of the oxidative burst markedly reduced 125I-labeled IgG binding in both group I and group II, with a greater decrement being seen in animals with intraabdominal sepsis. Further, in group II, PMN recycling of the Fc gamma receptor to the cell surface after generation of the oxidative burst was reduced by postoperative day 4. Binding of monoclonal antibodies to Fc gamma receptor II, but not Fc gamma receptor I/III markedly reduced intracellular candicidal activity. Immunofluorescence studies revealed a homogeneous pattern of FITC-IgG uptake by nearly all group I PMNs, whereas by postoperative day 8 a substantial number of PMNs from group II failed to internalize the FITC-IgG. These studies suggest that untreated intraabdominal sepsis reduces PMN candicidal activity and that this is due, in part, to altered PMN Fc gamma receptor ligand interactions.

  2. Fc gamma R-dependent mitogen-activated protein kinase activation in leukocytes: a common signal transduction event necessary for expression of TNF-alpha and early activation genes

    PubMed Central

    1996-01-01

    Cross-linking the receptors for the Fc domain of IgG (Fc gamma R) on leukocytes induces activation of protein tyrosine kinases. The intermediary molecules that transduce to the nucleus the signals leading to induction of the diverse biological responses mediated by these receptors are not clearly identified. We have investigated whether mitogen-activated protein kinases (MAPK) are involved in transmembrane signaling via the three Fc gamma R present on monocytic, polymorphonuclear, and natural killer (NK) cells. Our results indicate that occupancy of Fc gamma RI and Fc gamma RII on the monocytic cell line THP-I and on polymorphonuclear leukocytes (PMN) induces, transiently and with fast kinetics, MAPK phosphorylation, as indicated by decreased electrophoretic mobility in sodium dodecyl sulfate- polyacrylamide gel electrophoresis, and increased amounts of the proteins in antiphosphotyrosine antibody immunoprecipitates. This, associated with increased enzymatic activity, also occurs upon stimulation of the transmembrane isoform of CD16 (Fc gamma RIIIA) in NK cells and in a T cell line expressing transfected Fc gamma RIIIA alpha ligand-binding chain in association with zeta, but not upon stimulation of the glycosil-phosphatidylinositol-anchored Fc gamma RIIIB on PMN. Using the specific MAP kinase kinase inhibitor-PD 098059, we show that activation of MAPK is necessary for the Fc gamma R-dependent induction of c-fos and tumor necrosis factor alpha mRNA expression in monocytes and NK cells. These results underscore the role of MAPK as signal- transducing molecules controlling the expression of different genes relevant to leukocyte biology upon Fc gamma R stimulation. PMID:9064320

  3. Interferon enhances the expression of Fc gamma receptors.

    PubMed

    Fridman, W H; Gresser, I; Bandu, M T; Aguet, M; Neauport-Sautes, C

    1980-05-01

    Murine T2D4 cells derived from a T cell hybrid line were incubated with partially purified or electrophoretically pure mouse interferon and tested for the expression of Fc gamma R as assessed by a) counting the number of cells forming rosettes with IgG-sensitized sheep erythrocytes, and b) incubating the cells with heat-aggregated rabbit IgG and then determining either the number of cells stained with fluorescein conjugated goat anti-rabbit IgG or the extent of labeling by using radioactive iodinated staphylococcus protein A. Although interferon induced a rapid increase in Fc gamma R expression on the Fc gamma R-positive T2D4 cells, it did not induce either Fc gamma R on the Fc gamma R negative BW5147 cells or Fc gamma R on either cell line. Human leukocyte interferon enhanced the expression of Fc gamma R on human Burkitt cells (Daudi) but did not affect the expression of Fc gamma R on mouse cells. We suggest that interferon may influence several effector functions of the immune system by modulating Fc receptor expression. PMID:6154103

  4. Fc gamma receptor IIIb enhances Fc gamma receptor IIa function in an oxidant-dependent and allele-sensitive manner.

    PubMed Central

    Salmon, J E; Millard, S S; Brogle, N L; Kimberly, R P

    1995-01-01

    Two classes of receptors for IgG, Fc gamma RIIa and Fc gamma RIIIb, both of which exist in two allelic forms, are expressed on human neutrophils. Neutrophils from normal donors, homozygous for the different allelic phenotypes of Fc gamma RIIIb, have significantly different levels of Fc gamma receptor-mediated phagocytosis of IgG-opsonized erythrocytes (EA). However, the observation that Fc gamma RIIIb mediates phagocytosis of specific mAb-targeted erythrocytes poorly suggests that this receptor may influence EA internalization by Fc gamma RIIa in an allele-sensitive fashion. Donors homozygous for the NA1 allele of Fc gamma RIIIb showed greater activation of Fc gamma RIIa after Fc gamma RIIIb cross-linking than donors homozygous for the NA2 allele of Fc gamma RIIIb. This increase in receptor-specific internalization reflects both an increase in ligand binding by Fc gamma RIIa and an increase in internalization efficiency of targets bound. Activation of Fc gamma RIIa by Fc gamma RIIIb is transferable by supernatants from activated cells and is blocked by inhibitors of reactive oxygen species and the H2O2-myeloperoxidase-chloride system and by serine protease inhibitors. Thus, cross-linking of Fc gamma RIIIb, which leads to neutrophil degranulation and the generation of reactive oxygen intermediates, in turn alters Fc gamma RIIa avidity and efficiency. These oxidant-mediated changes in Fc gamma RIIa function provide a novel mechanism for receptors to collaborate in both an autocrine and paracrine fashion. The allele sensitivity of these effects suggests that Fc gamma receptor polymorphisms may be inherited disease susceptibility factors in host defense against infection and in the development of autoimmunity. Images PMID:7769129

  5. Structural recognition and functional activation of Fc[gamma]R by innate pentraxins

    SciTech Connect

    Lu, Jinghua; Marnell, Lorraine L.; Marjon, Kristopher D.; Mold, Carolyn; Du Clos, Terry W.; Sun, Peter D.

    2009-10-05

    Pentraxins are a family of ancient innate immune mediators conserved throughout evolution. The classical pentraxins include serum amyloid P component (SAP) and C-reactive protein, which are two of the acute-phase proteins synthesized in response to infection. Both recognize microbial pathogens and activate the classical complement pathway through C1q. More recently, members of the pentraxin family were found to interact with cell-surface Fc{gamma} receptors (Fc{gamma}R) and activate leukocyte-mediated phagocytosis. Here we describe the structural mechanism for pentraxin's binding to Fc{gamma}R and its functional activation of Fc{gamma}R-mediated phagocytosis and cytokine secretion. The complex structure between human SAP and Fc{gamma}RIIa reveals a diagonally bound receptor on each SAP pentamer with both D1 and D2 domains of the receptor contacting the ridge helices from two SAP subunits. The 1:1 stoichiometry between SAP and Fc{gamma}RIIa infers the requirement for multivalent pathogen binding for receptor aggregation. Mutational and binding studies show that pentraxins are diverse in their binding specificity for Fc{gamma}R isoforms but conserved in their recognition structure. The shared binding site for SAP and IgG results in competition for Fc{gamma}R binding and the inhibition of immune-complex-mediated phagocytosis by soluble pentraxins. These results establish antibody-like functions for pentraxins in the Fc{gamma}R pathway, suggest an evolutionary overlap between the innate and adaptive immune systems, and have new therapeutic implications for autoimmune diseases.

  6. Novel Fc gamma receptor I family gene products in human mononuclear cells.

    PubMed Central

    Porges, A J; Redecha, P B; Doebele, R; Pan, L C; Salmon, J E; Kimberly, R P

    1992-01-01

    Unlike the human Fc gamma RII and Fc gamma RIII families, which exhibit considerable diversity at both the nucleic acid and protein levels, the human Fc gamma RI family has only a single recognized product expressed as a 70-kD cell surface receptor with high affinity for monomeric IgG (hFc gamma RIa1). Using both polymerase chain reaction-based amplification and Northern hybridization, we document multiple interferon-gamma-inducible hFc gamma RI RNA transcripts in human mononuclear cells and neutrophils. The sequences of two of these Fc gamma RI related transcripts indicate that they are alternatively spliced products of a second Fc gamma RI family gene, termed Fc gamma RIB. The cDNA derived from the larger of these transcripts, termed hFc gamma RIb1, encodes a surface molecule that is not recognized by Fc gamma RI specific monoclonal antibodies when transfected into COS-7 cells. Unlike the interferon-gamma-inducible hFc gamma RIA gene product, hFc gamma RIb1 does not bind monomeric IgG with high affinity. However, both hFc gamma RIa1 and hFc gamma RIb1 do bind aggregated human IgG. Previously unrecognized diversity within the hFc gamma RI family includes an interferon-gamma-inducible, putative low affinity Fc gamma receptor that may play an important role in the mechanism by which Fc gamma receptors participate in the humoral immune response. Images PMID:1430234

  7. Expression and characterization of a truncated murine Fc gamma receptor

    PubMed Central

    1988-01-01

    We have isolated a recombinant secreted Fc gamma R beta molecule by deletion of the transmembrane and cytoplasmic domains encoding sequence from a Fc gamma R beta 1 cDNA clone, and insertion of the truncated cDNA into a eukaryotic expression vector, pcEXV-3. To express and amplify the production of the truncated Fc gamma R beta molecule, we transfected the truncated cDNA plasmid into a dihydrofolate reductase- minus CHO cell line along with a dhfr minigene, and amplified the gene products with methotrexate. The resulting cell line secretes 2-3 micrograms/ml/24 h of truncated Fc gamma R beta, which can be readily purified by affinity chromatography on IgG-Sepharose. The truncated Fc gamma R beta has a Mr of 31-33,000 on SDS-PAGE and is glycosylated. N- glycosidase F cleavage reduces the Mr to 19,000, consistent with the size of the truncated product, 176 amino acid residues. There are two disulfide bonds in the protein. Binding of immune complexes formed between DNP20BSA and anti-DNP mAbs reveals better binding of IgG1 aggregates than that of IgG2b and IgG2a aggregates. The binding of the immune complexes was somewhat better at more acidic pH, in contrast to previous experiments with binding of purified Fc gamma R to immune complex-coated beads. We were surprised to observe that the truncated Fc gamma R beta did not react with the anti-Fc gamma R mAb 6B7C. Previous work had shown that 6B7C reacts with Fc gamma R on immunoblots, fails to bind to the surface of resting B cells and peritoneal macrophages, but does bind to macrophage cell lines and LPS- stimulated B cells. We show, by binding of mAb 6B7C to a peptide conjugate, that the 6B7C epitope lies within residues 169-183 of the intact Fc gamma R beta, which is just outside the plasma membrane. The availability of the truncated Fc gamma R beta in microgram quantities should facilitate further analysis of structure and function of these receptors. PMID:2450951

  8. Enhanced expression of Fc receptors on neutrophils from calves with leukocyte adhesion deficiency.

    PubMed

    Nagahata, H; Higuchi, H; Nochi, H; Tamoto, K; Noda, H; Kociba, G J

    1995-01-01

    The expression of Fc receptors for immunoglobulin G(IgG) and concanavalin A (con A)-binding receptors, luminol-dependent chemiluminescent (LDCL) responses, and the effect of anti-bovine IgG on LDCL responses were evaluated in neutrophils from Holstein calves with leukocyte adhesion deficiency (BLAD). Neutrophils from affected calves showed a 2.1- to 2.5-fold increase in Fc receptor expression compared with those of control calves by flow cytometric analysis. Con A-binding activities of neutrophils from affected calves were similar to those of control calves. Neutrophils from a calf with BLAD, when stimulated with zymosan opsonized with bovine serum (OPZ), heat-aggregated bovine IgG (Agg-bovine IgG), sheep red blood cells (SRBC) sensitized with anti-SRBC antibody (SRBC-anti-SRBC Ab), or con A had LDCL responses of 36 (P < 0.05), 77, 126 and 119% of peak LDCL values of controls, respectively. The NBT-reducing value of neutrophils from a calf with BLAD when stimulated with Agg-bovine IgG after pretreatment with anti-bovine IgG was 116.5% of the values of neutrophils from control calves, but the difference was not significant. The LDCL responses of neutrophils from a control calf and a calf with BLAD stimulated with OPZ were inhibited markedly by pre-incubation with anti-bovine IgG antiserum at concentrations ranging from 1.25 to 20 or 40 micrograms/ml. Although an increase in Fc receptor expression on neutrophils from calves with BLAD was observed, the LDCL responses stimulated with SRBC-anti-SRBC Ab and NBT-reducing activity stimulated with Agg-bovine IgG after pretreatment with anti-bovine IgG did not correlate significantly with the increased Fc receptor expression. These results support that neutrophil functions mediated by the Fc receptors are associated synergistically with the presence of the complement receptor type 3 (CR3)(CD11b/CD18). PMID:8577284

  9. N-Formyl-Methionyl-Leucyl-Phenylalanine Inhibits both Gamma Interferon- and Interleukin-10-Induced Expression of FcγRI on Human Monocytes

    PubMed Central

    Beigier-Bompadre, Macarena; Barrionuevo, Paula; Alves-Rosa, Fernanda; Rubel, Carolina J.; Palermo, Marina S.; Isturiz, Martín A.

    2001-01-01

    Three different classes of receptors for the Fc portion of immunoglobulin G (FcγRs), FcγRI, FcγRII, and FcγRIII, have been identified on human leukocytes. One of them, FcγRI, is a high-affinity receptor capable of induction of functions that include phagocytosis, respiratory burst, antibody-dependent cell-mediated cytotoxicity (ADCC), and secretion of cytokines. This receptor is expressed on mononuclear phagocytes, and this expression is regulated by cytokines and hormones such as gamma interferon (IFN-γ), IFN-β, interleukin-10 (IL-10), and glucocorticoids. We have recently demonstrated that the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) is capable of inducing a time-dependent downregulation of both FcγRIIIB and FcγRII in human neutrophils, altering FcγR-dependent functions. Considering the biological relevance of the regulation of FcγRI, we investigated the effect of FMLP on the overexpression of FcγRI induced by both IFN-γ and IL-10 on human monocytes. We demonstrate that FMLP significantly abrogated IFN-γ- and IL-10-induced FcγRI expression, although its basal level of expression was not altered. However, other IFN-γ-mediated effects such as the overexpression of the major histocompatibility complex class II antigens and the enhancement of lipopolysaccharide-induced secretion of tumor necrosis factor alpha were not affected by FMLP treatment. The formyl peptide completely inhibited the IFN-γ- and IL-10-induced enhancement of ADCC and phagocytosis carried out by adherent cells. The inhibitory effect of FMLP on FcγRI upregulation could exert an important regulatory effect during the evolution of bacterial infections. PMID:11238229

  10. An alternative Fc gamma-receptor ligand: potential role in T-cell development.

    PubMed Central

    Sandor, M; Galon, J; Takacs, L; Tatsumi, Y; Mueller, A L; Sautes, C; Lynch, R G

    1994-01-01

    Fetal pre-T cells express low-affinity receptors for IgG (Fc gamma R) at a developmental stage prior to the rearrangement and expression of immunoglobulin genes. The present studies investigated the possible functional significance of Fc gamma R on fetal pre-T cells. Between 13 and 17 days of fetal development a subpopulation of T-cell receptor-, Thy-1+ thymocytes express for gamma R. The same cells contain mRNA for several forms of Fc gamma R (Fc gamma RII beta 1, beta 2, and Fc gamma RIII). Concurrently, a Pgp-1-, Thy-1-, surface-immunoglobulin- fetal thymic cell binds recombinant soluble Fc gamma R. In principle this cell can interact with the pre-T cells through this counter-receptor. To test this possibility anti-Fc gamma RII/III antibody (2.4G2) was injected into pregnant mice and then into their offspring for 6 wk postpartum. The injected antibody induced a slight increase in the proportion of CD4 or CD8 single-positive, alpha/beta T cells in the thymus. However, in fetal thymic cultures in the presence of 2.4G2 or the recombinant soluble Fc gamma R there was an accelerated differentiation of thymocytes to single-positive, CD3-bright, heat-stable antigen-dull, alpha/beta T cells. These experiments show that Fc gamma Rs are present on pre-T cells during early fetal thymic development, and that a non-IgG ligand of the Fc gamma R is expressed concurrently on Thy- fetal thymocytes. Furthermore, the presumed interaction of Fc gamma R and the alternative ligand(s) influences T-cell development. IgG binding could be an adapted function of Fc gamma Rs, and, as shown for many members of the Ig super family, these receptors may have originally served as cell-cell recognition/interaction molecules required for hematopoietic development. Images Fig. 2 PMID:7809135

  11. Phosphatidylinositol-3 kinase activation induced upon Fc gamma RIIIA- ligand interaction

    PubMed Central

    1994-01-01

    Induced activation of protein tyrosine kinase(s) is a central event in signal transduction mediated via the low affinity receptor for IgG (Fc gamma RIIIA, CD16) in natural killer (NK) cells. Tyrosine phosphorylation may affect the function of several protein directly, or indirectly by inducing their association with other tyrosine phosphorylated proteins. Here, we report that Fc gamma RIII stimulation induces activation of phosphatidylinositol (PI)-3 kinase in NK cells. Phosphotyrosine immunoprecipitates from Fc gamma RIII-stimulated NK cells contain PI-kinase activity and PI-3 kinase can be directly precipitated from them. Conversely, a series of tyrosine-phosphorylated proteins is coprecipitated with PI-3 kinase from the stimulated, but not from control cells. Analogous results obtained using Jurkat T cells expressing transfected Fc gamma RIIIA alpha ligand binding chain in association with gamma 2 or zeta 2 homodimers indicate that both complexes transduce this effect, although the Fc gamma RIIIA-zeta 2 complexes do so with greater efficiency. Accumulation of phosphoinositide D3 phosphorylated products in stimulated cells confirms PI-3 kinase activation, indicating the participation of this enzyme in Fc gamma RIIIA-mediated signal transduction. PMID:8294866

  12. Structural Basis for Fc[gamma]RIIa Recognition of Human IgG and Formation of Inflammatory Signaling Complexes

    SciTech Connect

    Ramsland, Paul A.; Farrugia, William; Bradford, Tessa M.; Sardjono, Caroline Tan; Esparon, Sandra; Trist, Halina M.; Powell, Maree S.; Tan, Peck Szee; Cendron, Angela C.; Wines, Bruce D.; Scott, Andrew M.; Hogarth, P. Mark

    2011-09-20

    The interaction of Abs with their specific FcRs is of primary importance in host immune effector systems involved in infection and inflammation, and are the target for immune evasion by pathogens. Fc{gamma}RIIa is a unique and the most widespread activating FcR in humans that through avid binding of immune complexes potently triggers inflammation. Polymorphisms of Fc{gamma}RIIa (high responder/low responder [HR/LR]) are linked to susceptibility to infections, autoimmune diseases, and the efficacy of therapeutic Abs. In this article, we define the three-dimensional structure of the complex between the HR (arginine, R134) allele of Fc{gamma}RIIa (Fc{gamma}RIIa-HR) and the Fc region of a humanized IgG1 Ab, hu3S193. The structure suggests how the HR/LR polymorphism may influence Fc{gamma}RIIa interactions with different IgG subclasses and glycoforms. In addition, mutagenesis defined the basis of the epitopes detected by FcR blocking mAbs specific for Fc{gamma}RIIa (IV.3), Fc{gamma}RIIb (X63-21), and a pan Fc{gamma}RII Ab (8.7). The epitopes detected by these Abs are distinct, but all overlap with residues defined by crystallography to contact IgG. Finally, crystal structures of LR (histidine, H134) allele of Fc{gamma}RIIa and Fc{gamma}RIIa-HR reveal two distinct receptor dimers that may represent quaternary states on the cell surface. A model is presented whereby a dimer of Fc{gamma}RIIa-HR binds Ag-Ab complexes in an arrangement that possibly occurs on the cell membrane as part of a larger signaling assembly.

  13. Effect of Low Dose Gamma Irradiation together with Lipid A on Human Leukocytes Activities In Vitro

    NASA Astrophysics Data System (ADS)

    Belyakova, E.; Dubnickova, M.; Boreyko, A.

    2010-01-01

    The influence of gamma irradiation and of Lipid A from Escherichia coli on phagocytosis, lyzosyme and peroxidase activities of human leukocytes, in vitro was investigated. Leukocytes samples were irradiated with 1 and 5 Gy, respectively. The number of irradiated leukocytes was decreased in the irradiated samples. Only samples with additive Lipid A were not damaged by irradiation. The Lipid A had positive influence on biological activities of the irradiated leukocytes.

  14. Complement component C3b and immunoglobulin Fc receptors on neutrophils from calves with leukocyte adhesion deficiency.

    PubMed

    Worku, M; Paape, M J; Di Carlo, A; Kehrli, M E; Marquardt, W W

    1995-04-01

    Receptors for opsonins, such as complement component C3b (CR1) and immunoglobulins, Fc receptors, interact with adhesion glycoproteins in mediating immune functions. Defects in expression of the adhesion glycoproteins CD11/CD18 results in severely hampered in vitro and in vivo adherence-related functions of leukocytes. Little is known regarding the effect of leukocyte adhesion deficiency (LAD) on ligand binding and receptor expression. We investigated the binding and expression of CR1 and Fc receptors by bovine neutrophils isolated from dairy calves suffering from LAD, compared with clinically normal (hereafter referred to as normal) age-matched calves. Neutrophils were also assayed for endogenously bound IgG and IgM and for exogenous binding of C3b, IgG1, IgG2, IgM, and aggregated IgG (aIgG), using flow cytometry. Luminol-enhanced chemiluminescence (CL) production in response to IgG2 opsonized zymosan was studied, and specific inhibition of CL was used to determine the specificity of IgG2 binding. Activation of protein kinase C with phorbol myristate acetate was used to determine the effect of cellular activation on expression of CR1. A greater percentage of neutrophils from normal calves bound C3b than did neutrophils from LAD-affected calves. Receptor expression was similar. Activation with phorbol myristate acetate resulted in increased expression of CR1 on neutrophils from normal and LAD-affected calves, but expression was almost twofold greater on neutrophils from normal calves. There was no difference between LAD-affected and normal calves in percentage of neutrophils that bound endogenous IgG and IgM. A greater percentage of neutrophils from normal calves bound exogenous IgM than did neutrophils from LAD-affected calves.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7785817

  15. Localization of Fc gamma receptors and complement receptors CR1 on human peripheral nerve fibres by immunoelectron microscopy.

    PubMed

    Vedeler, C A; Nilsen, R; Matre, R

    1989-06-01

    The localization of receptors for the Fc part of IgG (Fc gamma R) and for the complement C3b/C4b components (CR1) on human peripheral nerve fibres was investigated by indirect immunoperoxidase staining of frozen nerve sections with monoclonal antibodies. Transmission electron microscopy revealed that Fc gamma R and CR1 are localized to the entire surface membrane and inner membrane (axolemma) of the Schwann cell. Myelin and axons were not stained. The presence of Fc gamma R and CR1 in human Schwann cells adds further evidence for the immunocompetence of these cells.

  16. Ligation of Fc gamma receptor IIB inhibits antibody-dependent enhancement of dengue virus infection.

    PubMed

    Chan, Kuan Rong; Zhang, Summer Li-Xin; Tan, Hwee Cheng; Chan, Ying Kai; Chow, Angelia; Lim, Angeline Pei Chiew; Vasudevan, Subhash G; Hanson, Brendon J; Ooi, Eng Eong

    2011-07-26

    The interaction of antibodies, dengue virus (DENV), and monocytes can result in either immunity or enhanced virus infection. These opposing outcomes of dengue antibodies have hampered dengue vaccine development. Recent studies have shown that antibodies neutralize DENV by either preventing virus attachment to cellular receptors or inhibiting viral fusion intracellularly. However, whether the antibody blocks attachment or fusion, the resulting immune complexes are expected to be phagocytosed by Fc gamma receptor (FcγR)-bearing cells and cleared from circulation. This suggests that only antibodies that are able to block fusion intracellularly would be able to neutralize DENV upon FcγR-mediated uptake by monocytes whereas other antibodies would have resulted in enhancement of DENV replication. Using convalescent sera from dengue patients, we observed that neutralization of the homologous serotypes occurred despite FcγR-mediated uptake. However, FcγR-mediated uptake appeared to be inhibited when neutralized heterologous DENV serotypes were used instead. We demonstrate that this inhibition occurred through the formation of viral aggregates by antibodies in a concentration-dependent manner. Aggregation of viruses enabled antibodies to cross-link the inhibitory FcγRIIB, which is expressed at low levels but which inhibits FcγR-mediated phagocytosis and hence prevents antibody-dependent enhancement of DENV infection in monocytes. PMID:21746897

  17. Organization of the human T cell receptor [zeta]/[eta] gene and its genetic linkage to the Fc[gamma]RII-Fc[gamma]RIII gene cluster

    SciTech Connect

    Jensen, J.P.; Hou, D.; Taylor, A. ); Dean, M. ); Ramsburg, M. ); Weissman, A.W. DCBDC/National Cancer Institute National Institute of Health, Bethesda, MD )

    1992-04-15

    The [zeta]-subunit is the most recently characterized stoichiometric human TCR component. In this study the authors describe the molecular organization of the human [zeta]-gene. The [zeta] transcript is generated as the spliced product of eight exons that are separated by distances of 0.7 kb to more than 8 kb. Ribonuclease protection studies revealed multiple transcription initiation sites distributed over a range of approximately 115 bases. A variable number tandem repeat restriction fragment polymorphism contained within the structural gene has allowed for the localization of [zeta] within the human genome. Additionally, a restriction fragment polymorphism within the Fc[gamma]RII-Fc[gamma]RIII gene cluster has allowed for its localization on the map of human chromosome 1q and for the establishment of its linkage to the [zeta]-gene locus. A region that is highly homologous on a nucleotide level with the [eta]-exon of the murine [zeta]-gene is localized to the 3[prime] region of the human [zeta]-gene. Surprisingly, translation of this region into protein results in a structure that is markedly divergent from its murine counterpart. This finding has important implications regarding the potential role of [eta] in T cell function. 60 refs., 7 figs., 1 tab.

  18. Leukocyte immunoglobulin-like receptor B4 regulates key signalling molecules involved in FcγRI-mediated clathrin-dependent endocytosis and phagocytosis

    PubMed Central

    Park, Mijeong; Raftery, Mark J.; Thomas, Paul S.; Geczy, Carolyn L.; Bryant, Katherine; Tedla, Nicodemus

    2016-01-01

    FcγRI cross-linking on monocytes may trigger clathrin-mediated endocytosis, likely through interaction of multiple intracellular molecules that are controlled by phosphorylation and dephosphorylation events. However, the identity of phospho-proteins and their regulation are unknown. We proposed the leukocyte immunoglobulin-like receptor B4 (LILRB4) that inhibits FcγRI-mediated cytokine production via Tyr dephosphorylation of multiple kinases, may also regulate endocytosis/phagocytosis through similar mechanisms. FcγRI and/or LILRB4 were antibody-ligated on THP-1 cells, lysates immunoprecipitated using anti-pTyr antibody and peptides sequenced by mass spectrometry. Mascot Search identified 25 Tyr phosphorylated peptides with high confidence. Ingenuity Pathway Analysis revealed that the most significantly affected pathways were clathrin-mediated endocytosis and Fc-receptor dependent phagocytosis. Tyr phosphorylation of key candidate proteins in these pathways included common γ-chain of the Fc receptors, Syk, clathrin, E3 ubiquitin protein ligase Cbl, hepatocyte growth factor-regulated tyrosine kinase substrate, tripartite motif-containing 21 and heat shock protein 70. Importantly, co-ligation of LILRB4 with FcγRI caused significant dephosphorylation of these proteins and was associated with suppression of Fc receptor-dependent uptake of antibody-opsonised bacterial particles, indicating that LILRB4. These results suggest that Tyr phosphorylation may be critical in FcγRI-dependent endocytosis/phagocytosis that may be regulated by LILRB4 by triggering dephosphorylation of key signalling proteins. PMID:27725776

  19. Crosslinking of surface antibodies and Fc sub. gamma. receptors: Theory and application

    SciTech Connect

    Wofsy, C.; Goldstein, B. Los Alamos National Lab., NM )

    1991-03-15

    In an immune response, the crosslinking of surface immunoglobulin (sIg) on B cells by multiply-bound ligand activates a range of cell responses, culminating in the production of antibody-secreting cells. However, when the crosslinking agent is itself an antibody, B cell activation is inhibited. Solution antibody (IgG) can bind simultaneously to sIg and to another cell surface receptor, Fc{sub {gamma}}R, co-crosslinking' the distinct receptors. Experiments point to co-crosslinking as the inhibitory signal. It is not clear how co-crosslinking inhibits B cell stimulation. The authors construct and analyze a mathematical model aimed at clarifying the nature and mechanisms of action of the separate cell signals controlling B cell responses to antibodies. Basophils and mast cells respond to the crosslinking of cell surface antibody by releasing histamine. Like B cells, basophils also express FC{sub {gamma}}R. They use their model to analyze new data on the effect of antibody-induced co-crosslinking of the two types of receptor on this family of cells. Predictions of the model indicate that an observed difference between the response patterns induced by antibodies and by antibody fragments that cannot bind to FC{sub {gamma}}R can be explained if co-crosslinking is neither inhibitory nor stimulatory in this system.

  20. Imaging and measuring the biophysical properties of Fc gamma receptors on single macrophages using atomic force microscopy

    SciTech Connect

    Li, Mi; Liu, Lianqing; Xi, Ning; Wang, Yuechao; Xiao, Xiubin; Zhang, Weijing

    2013-09-06

    Highlights: •Nanoscale cellular ultra-structures of macrophages were observed. •The binding affinities of FcγRs were measured directly on macrophages. •The nanoscale distributions of FcγRs were mapped on macrophages. -- Abstract: Fc gamma receptors (FcγR), widely expressed on effector cells (e.g., NK cells, macrophages), play an important role in clinical cancer immunotherapy. The binding of FcγRs to the Fc portions of antibodies that are attached to the target cells can activate the antibody-dependent cell-mediated cytotoxicity (ADCC) killing mechanism which leads to the lysis of target cells. In this work, we used atomic force microscopy (AFM) to observe the cellular ultra-structures and measure the biophysical properties (affinity and distribution) of FcγRs on single macrophages in aqueous environments. AFM imaging was used to obtain the topographies of macrophages, revealing the nanoscale cellular fine structures. For molecular interaction recognition, antibody molecules were attached onto AFM tips via a heterobifunctional polyethylene glycol (PEG) crosslinker. With AFM single-molecule force spectroscopy, the binding affinities of FcγRs were quantitatively measured on single macrophages. Adhesion force mapping method was used to localize the FcγRs, revealing the nanoscale distribution of FcγRs on local areas of macrophages. The experimental results can improve our understanding of FcγRs on macrophages; the established approach will facilitate further research on physiological activities involved in antibody-based immunotherapy.

  1. The Fc receptor gamma-chain and the tyrosine kinase Syk are essential for activation of mouse platelets by collagen.

    PubMed Central

    Poole, A; Gibbins, J M; Turner, M; van Vugt, M J; van de Winkel, J G; Saito, T; Tybulewicz, V L; Watson, S P

    1997-01-01

    Activation of mouse platelets by collagen is associated with tyrosine phosphorylation of multiple proteins including the Fc receptor gamma-chain, the tyrosine kinase Syk and phospholipase Cgamma2, suggesting that collagen signals in a manner similar to that of immune receptors. This hypothesis has been tested using platelets from mice lacking the Fc receptor gamma-chain or Syk. Tyrosine phosphorylation of Syk and phospholipase Cgamma2 by collagen stimulation is absent in mice lacking the Fc receptor gamma-chain. Tyrosine phosphorylation of phospholipase Cgamma2 by collagen stimulation is also absent in mice platelets which lack Syk, although phosphorylation of the Fc receptor gamma-chain is maintained. In contrast, tyrosine phosphorylation of platelet proteins by the G protein-coupled receptor agonist thrombin is maintained in mouse platelets deficient in Fc receptor gamma-chain or Syk. The absence of Fc receptor gamma-chain or Syk is accompanied by a loss of secretion and aggregation responses in collagen- but not thrombin-stimulated platelets. These observations provide the first direct evidence of an essential role for the immunoreceptor tyrosine-based activation motif (ITAM) in signalling by a non-immune receptor stimulus. PMID:9171347

  2. Role of Fc Gamma Receptors in Triggering Host Cell Activation and Cytokine Release by Borrelia burgdorferi

    PubMed Central

    Talkington, Jeffrey; Nickell, Steven P.

    2001-01-01

    Borrelia burgdorferi, the spirochetal bacterium that causes human Lyme disease, encodes numerous lipoproteins which have the capacity to trigger the release of proinflammatory cytokines from a variety of host cell types, and it is generally believed that these cytokines contribute to the disease process in vivo. We previously reported that low-passage-number infectious B. burgdorferi spirochetes express a novel lipidation-independent activity which induces secretion of the proinflammatory cytokine tumor necrosis factor alpha (TNF-α) by the mouse MC/9 mast cell line. Using RNase protection assays, we determined that mast cells exposed in vitro to low-passage-number, but not high-passage-number, B. burgdorferi spirochetes show increased expression of additional mRNAs representing several chemokines, including macrophage-inflammatory protein 1α (MIP-1α), MIP-1β, and TCA3, as well as the proinflammatory cytokine interleukin-6. Furthermore, mast cell TNF-α secretion can be inhibited by the phosphatidylinositol 3-kinase inhibitor wortmannin and also by preincubation with purified mouse immunoglobulin G1 (IgG1) and IgG2a, but not mouse IgG3, and by a mouse Fc gamma receptor II and III (FcγRII/III)-specific rat monoclonal antibody, suggesting the likely involvement of host FcγRIII in B. burgdorferi-mediated signaling. A role for passively adsorbed rabbit or bovine IgG or serum components in B. burgdorferi-mediated FcγR signaling was excluded in control experiments. These studies confirm that low-passage-number B. burgdorferi spirochetes express a novel activity which upregulates the expression of a variety of host cell chemokine and cytokine genes, and they also establish a novel antibody-independent role for FcγRs in transduction of activation signals by bacterial products. PMID:11119532

  3. Contribution of PIP-5 kinase I{alpha} to raft-based Fc{gamma}RIIA signaling

    SciTech Connect

    Szymanska, Ewelina; Korzeniowski, Marek; Raynal, Patrick; Sobota, Andrzej; Kwiatkowska, Katarzyna

    2009-04-01

    Receptor Fc{gamma}IIA (Fc{gamma}RIIA) associates with plasma membrane rafts upon activation to trigger signaling cascades leading to actin polymerization. We examined whether compartmentalization of PI(4,5)P{sub 2} and PI(4,5)P{sub 2}-synthesizing PIP5-kinase I{alpha} to rafts contributes to Fc{gamma}RIIA signaling. A fraction of PIP5-kinase I{alpha} was detected in raft-originating detergent-resistant membranes (DRM) isolated from U937 monocytes and other cells. The DRM of U937 monocytes contained also a major fraction of PI(4,5)P{sub 2}. PIP5-kinase I{alpha} bound PI(4,5)P{sub 2}, and depletion of the lipid displaced PIP5-kinase I{alpha} from the DRM. Activation of Fc{gamma}RIIA in BHK transfectants led to recruitment of the kinase to the plasma membrane and enrichment of DRM in PI(4,5)P{sub 2}. Immunofluorescence studies revealed that in resting cells the kinase was associated with the plasma membrane, cytoplasmic vesicles and the nucleus. After Fc{gamma}RIIA activation, PIP5-kinase I{alpha} and PI(4,5)P{sub 2} co-localized transiently with the activated receptor at distinct cellular locations. Immunoelectron microscopy studies revealed that PIP5-kinase I{alpha} and PI(4,5)P{sub 2} were present at the edges of electron-dense assemblies containing activated Fc{gamma}RIIA in their core. The data suggest that activation of Fc{gamma}RIIA leads to membrane rafts coalescing into signaling platforms containing PIP5-kinase I{alpha} and PI(4,5)P{sub 2}.

  4. Short communication: Fc gamma receptors IIa and IIIa genetic polymorphisms do not predict HIV-1 disease progression in Kenyan women.

    PubMed

    Weis, Julie F; McClelland, R Scott; Jaoko, Walter; Mandaliya, Kishor N; Overbaugh, Julie; Graham, Susan M

    2015-03-01

    Genetic polymorphisms of the Fc gamma receptors (FcγR) IIa and IIIa have been implicated in the rate of HIV-1 disease progression, but results are inconsistent. We aimed to determine the association between these polymorphisms and disease progression in a cohort of HIV-1 seroconverters from Mombasa, Kenya. Neither FcγRIIa nor FcγRIIIa genotypes were predictive of set point viral load, viral load increase, CD4 decline, or HIV-1 disease progression (time to CD4 count <200 cells/mm(3), death, or treatment initiation). Our results suggest that FcγR polymorphisms might not be an important indicator of viral control and disease progression in this population.

  5. Age-dependent alterations of Fc gamma receptor-mediated effector functions of human polymorphonuclear leucocytes.

    PubMed Central

    Fülöp, T; Fóris, G; Wórum, I; Leövey, A

    1985-01-01

    Changes in the effector functions in polymorphonuclear leucocytes (PMNL), harvested from blood of young and aged healthy subjects of both sexes, were studied. FC gamma-receptor (Fc gamma R)-mediated incorporation of IgG coated 51Cr-HRBC significantly increased in the aged male group, while the phagocytosis of pre-opsonized fungi (Saccharomyces cerevisiae and Candida albicans) was independent of both the age and sex. However, the intracellular killing capacity of neutrophils obtained from aged male subjects significantly decreased toward 51Cr-labelled c. albicans. The antibody-dependent cellular cytotoxicity (ADCC) was also impaired with ageing in both sexes. The age-dependent decrease in the effector functions of PMNL may be explained, among others, by the fact that during yeast cell incorporation the increased cAMP level does not return to the basic level in the old group. On the other hand, the cGMP level which increased in PMNL of aged subjects does not show any progressive increase as in the young subjects, but remains unchanged. The oxidative metabolism producing free radicals being necessary for the effective intracellular killing and ADCC diminished in PMNL of aged subjects of both sexes. The above findings indicate that the adaptation of cyclic nucleotide system and the oxidative burst to the cell activation becomes impaired with ageing. PMID:2994926

  6. Attenuated atherosclerotic lesions in apoe-fc gamma-chain-deficient hyperlipidemic mouse model is associated with inhibition of Th17 cells and promotion of regulatory T cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Though the presence of antioxidized low-density lipoprotein IgG is well documented in clinical and animal studies, the role for Fc gamma Rs to the progression of atherosclerosis has not been studied in detail. In the current study, we investigated the role for activating Fc gamma R in the progressio...

  7. Mapping the functional topography of Fc gamma with monoclonal antibodies: localization of epitopes interacting with the binding sites of Fc receptor on human K cells.

    PubMed

    Sármay, G; Jefferis, R; Klein, E; Benczur, M; Gergely, J

    1985-10-01

    A panel of monoclonal antibodies (mAb) specific for the C gamma 2, C gamma 3 or inter C gamma 2/C gamma 3 domain epitopes was tested for inhibition of antibody-dependent cellular cytotoxicity (ADCC) specific for anti-D IgG-coated erythrocytes. Significant inhibition of ADCC was demonstrable for some antibodies having specificity for C gamma 2 or C gamma 3 domain epitopes, while others gave no inhibition. Fab fragments of a representative C gamma 2-specific antibody (A55) and C gamma 3-specific antibody (x3a8) retained their inhibitory capacity in lymphocyte-mediated ADCC, but only A55 Fab inhibited monocyte-mediated lysis. Furthermore, the Fab portion of A55 completely abolished the complement-dependent enhancement of ADCC mediated by concanavalin A-stimulated cells, while x3a8 Fab had no effect in this system. On the other hand, x3a8 Fab inhibited the binding of anti-D IgG-sensitized erythrocytes to lymphocytes while A55 Fab did not influence this latter interaction. The results suggest that C gamma 2 domain-FcR interaction is essential for the triggering of lytic process both in lymphocyte and in monocyte-mediated ADCC, while C gamma 3 domain has no role in the latter but is responsible for the appropriate contact between effector lymphocytes and target cells. A site in the region of Lys274 appears to be critical for triggering of both lymphocyte and monocyte-mediated ADCC.

  8. Localization of Fc gamma receptors in the human central nervous system.

    PubMed

    Nyland, H; Nilsen, R

    1982-08-01

    Immune complexes of horseradish peroxidase (HRP) and rabbit IgG antibodies to HRP were used to study the Fc gamma receptors in the human central nervous system (CNS). The peroxidase activity was demonstrated with 3,3'-diaminobenzidine tetrahydrochloride and H2O2. The majority of the pia and arachnoid cells of the leptomeninges, the stroma cells of the arachnoid granulations and the adventitial cells in the perivascular spaces of the nervous tissue were stained. The villi of the choroid plexus were also stained. By electron microscopy the reaction products were localized to the plasma membranes of the stroma cells and at the basal aspects of the epithelial cells in the choroid villi. In addition, reaction product was demonstrated on pericytes of some of the brain capillaries. The immune complexes did not bind to the brain parenchyma.

  9. Identification of three FcR-positive T cell subsets (T gamma, T mu and T gamma mu) in the cerebrospinal fluid of multiple sclerosis patients.

    PubMed Central

    Merrill, J E; Biberfeld, G; Landin, S; Sidén, A; Norrby, E

    1980-01-01

    Proportions of T cells and T cell subsets, as identified by their Fc receptors (FcR) for IgM and IgG (Tmu and T gamma), were determined in the peripheral blood lymphocyte (PBL) and cerebrospinal fluid (CSF) lymphocyte populations in patients with multiple sclerosis (MS). On average, MS patients had 79% total T cells (62% of which were T gamma, 66% Tmu) in CSF lymphocytes compared to 66% total T cells (30% T gamma, 63% Tmu) in PBL. Normal age- and sex-matched controls PBL had 74% total T cells (20% T gamma, 54% Tmu). By direct observation using an indirect immunofluorescence assay, 41% of the CSF T gamma cells in MS patients bore receptors for IgM; these cells were designated T gamma mu and, according to the double-marker analysis, did not seem to correlate with disease stage. In MS PBL, 20% of T gamma cells were T gamma mu compared to 9% in the control PBL T gamma population. Thus, MS patients had a higher proportion of total T cells, T gamma cells and T gamma mu cells in their CSF than in their peripheral blood and than those populations found in normal control blood. The significance of this T gamma mu population for the continuing disease state in MS is discussed. PMID:6970641

  10. A single amino acid in the second Ig-like domain of the human Fc gamma receptor II is critical for human IgG2 binding.

    PubMed

    Warmerdam, P A; van de Winkel, J G; Vlug, A; Westerdaal, N A; Capel, P J

    1991-08-15

    The low-affinity human Fc gamma RIIa is encoded by a single gene with allelic variation, defined by low-responder and high-responder alleles (LR and HR). The HR Fc gamma RIIa transcript interacts strongly with murine (m) IgG1 complexes, in contrast to the LR Fc gamma RIIa. Furthermore, the transcripts can be discriminated by mAb 41H16, which recognizes an epitope expressed on the HR Fc gamma RIIa molecule. We report that this receptor is also polymorphic in its reactivity with human (h) IgG2. Binding studies using well-defined hIgG dimers revealed that LR Fc gamma RIIa molecules can efficiently bind hIgG2, in contrast to HR Fc gamma RIIa. Previous work of others showed one amino acid difference between the allelic forms of Fc gamma RII. We, however, found a second amino acid difference between both allelic forms. In this study, hybrid Fc gamma RIIa molecules were constructed to determine the epitope for mAb 41H16 and the binding domain for mIgG1 and hIgG2 complexes. Our data point to the importance of the amino acid at position 131, located in the second Ig-like domain of Fc gamma RIIa. When an arginine residue is present at amino acid position 131, the receptor is recognized by mAb 41H16. Furthermore, the receptor can bind mIgG1-sensitized indicator E, but binds hIgG2 dimers only weakly. When a histidine residue is present at this amino acid position, hIgG2 dimers do bind efficiently to Fc gamma RII, whereas mIgG1-sensitized E and mAb 41H16 exhibit a strongly diminished binding.

  11. Syk interacts with tyrosine-phosphorylated proteins in human platelets activated by collagen and cross-linking of the Fc gamma-IIA receptor.

    PubMed Central

    Yanaga, F; Poole, A; Asselin, J; Blake, R; Schieven, G L; Clark, E A; Law, C L; Watson, S P

    1995-01-01

    Activation of human platelets by cross-linking of the platelet low-affinity IgG receptor, the Fc gamma receptor IIA (Fc gamma-RIIA), or by collagen is associated with rapid phosphorylation on tyrosine of the non-receptor tyrosine kinase syk. Phosphorylation is still observed, albeit sometimes reduced, in the presence of a combination of a protein kinase C inhibitor, Ro 31-8220, and the intracellular calcium chelator, BAPTA-AM, demonstrating independence from phosphoinositide-specific phospholipase C (PLC) activity. In contrast, the combination of Ro 31-8220 and BAPTA-AM completely inhibits phosphorylation of syk in thrombin-stimulated platelets. Phosphorylation of syk increases its autophosphorylation activity measured in a kinase assay performed on syk immunoprecipitates. Fc gamma-RIIA also undergoes phosphorylation in syk immunoprecipitates from platelets activated by cross-linking of Fc gamma-RIIA but not by collagen, suggesting that it associates with the kinase. Consistent with this, tyrosine-phosphorylated Fc gamma-RIIA is precipitated by a glutathione S-transferase (GST) fusion protein containing the tandem src homology (SH2) domains of syk from Fc gamma-RIIA- but not collagen-activated cells. Two uncharacterized tyrosine-phosphorylated proteins of 40 and 65 kDa are uniquely precipitated by a GST fusion protein containing the tandem syk-SH2 domains in collagen-stimulated platelets. A peptide based on the antigen recognition activation motif (ARAM) of Fc gamma-RIIA, and phosphorylated on the two tyrosine residues found within this region, selectively binds syk from lysates of resting platelets; this interaction is not seen with a non-phosphorylated peptide. Kinase assays on Fc gamma-RIIA immunoprecipitates reveal the constitutive association of an unidentified kinase activity in resting cells which phosphorylates a 67 kDa protein. Syk is not detected in Fc gamma-RIIA immunoprecipitates from resting cells but associates with the receptor following activation

  12. Identification of residues within the extracellular domain 1 of bovine Fc gamma 2R essential for binding bovine IgG2.

    PubMed

    Morton, H C; Howard, C J; Storset, A K; Brandtzaeg, P

    2001-12-21

    Neutrophils and monocytes in cattle express a novel class of immunoglobulin Fc receptor, specific for bovine IgG2 (bIgG2), termed bFc gamma 2R. In cows, the ability of neutrophils to kill immunoglobulin-opsonized microorganisms appears to depend largely on this subclass, whose interaction with bFc gamma 2R initiates the killing process. bFc gamma 2R is a transmembrane glycoprotein consisting of two extracellular immunoglobulin-like domains, followed by a 19-amino acid membrane-spanning region and a short cytoplasmic tail. Although related to other mammalian Fc gamma Rs, bFc gamma 2R belongs to a novel gene family that includes the human killer cell inhibitory receptor and Fc alpha RI (CD89) proteins. We have shown previously (Morton, H. C., van Zandbergen, G., van Kooten, C., Howard, C. J., van de Winkel, J. G., and Brandtzaeg, P. (1999) J. Exp. Med. 189, 1715-1722) that like these proteins (and unlike other Fc gamma Rs), bFc gamma 2R binds bIgG2 via the membrane-distal extracellular domain 1 (EC1). In this present study, we introduced mutations into the predicted loop regions of the EC1 domain and assayed the resulting bFc gamma 2R mutants for their ability to bind bIgG2. Our results indicated that the bIgG2 binding site lies within the predicted F-G loop region of the EC1 domain. Furthermore, single amino acid mutational analysis of this region identified Phe-82 and Trp-87 as being critical for bIgG2 binding.

  13. Combined Effects of Gamma Radiation and High Dietary Iron on Peripheral Leukocyte Distribution and Function

    NASA Technical Reports Server (NTRS)

    Crucian, Brian E.; Morgan, Jennifer L. L.; Quiriarte, Heather A.; Sams, Clarence F.; Smith, Scott M.; Zwart, Sara R.

    2012-01-01

    Both radiation and increased iron stores can independently increase oxidative damage, resulting in protein, lipid and DNA oxidation. Oxidative stress increases the risk of many health problems including cancer, cataracts, and heart disease. This study, a subset of a larger interdisciplinary investigation of the combined effect of iron overload on sensitivity to radiation injury, monitored immune parameters in the peripheral blood of rats subjected to gamma radiation, high dietary iron or both. Specific immune measures consisted of: (1) peripheral leukocyte distribution, (2) plasma cytokine levels and (3) cytokine production profiles following whole blood mitogenic stimulation

  14. Preferential expression of human Fc gamma RIIIPMN (CD16) in paroxysmal nocturnal hemoglobinuria. Discordant expression of glycosyl phosphatidylinositol-linked proteins.

    PubMed Central

    Edberg, J C; Salmon, J E; Whitlow, M; Kimberly, R P

    1991-01-01

    The isoform of Fc gamma RIII (CD16) expressed on PMN has a GPI membrane anchor, and in paroxysmal nocturnal hemoglobinuria (PNH) there is a deficiency in Fc gamma RIII expression on PMN. Contrary to expectation, however, CD16 expression is preserved (albeit at reduced levels) in all affected PNH PMN that completely lack the GPI-anchored proteins DAF (CD55) and CD59. Fc gamma RIII negative PMN are not observed in any of the six PNH patients examined in this study. Analysis of the molecular weight of both glycosylated and deglycosylated Fc gamma RIII from PMN with reduced Fc gamma RIII expression indicates no variations in size relative to normal donor Fc gamma RIIIPMN. Indeed, the Fc gamma RIII expressed at intermediate levels is phosphatidylinositol-specific phospholipase C (PI-PLC)-sensitive. Thus, there is no evidence suggestive of expression of a transmembrane isoform and all data indicate that Fc gamma RIIIPMN on affected cells in PNH is a GPI-linked isoform. With Fc gamma RIIIPMN expression preserved at reduced levels on affected cells in PNH, PMN from PNH patients retain the capacity to internalize the Fc gamma RIIIPMN-specific probe E-ConA (at reduced levels) as well as IgG-opsonized erythrocytes. Reduced expression of GPI-anchored molecules on PNH PMN is not restricted to Fc gamma RIIIPMN since intermediate levels of CD59 were observed in the PNH PMN that were decay-accelerating factor (DAF)-negative and Fc gamma RIIIPMN intermediate. In addition, discordant expression of GPI-linked molecules in individual cells is not restricted to PMN since DAF+/CD14- monocytes were observed in one PNH patient. These data suggest that, when analyzed on an individual cell level, the GPI anchor defect in PNH is not absolute and must involve either a hierarchy of access of different protein molecules to available GPI anchors, distinct anchor biochemistries for the different proteins, or differential regulation of protein-anchor assembly. Images PMID:1702101

  15. Association of a coding polymorphism in Fc gamma receptor 2A and graft survival in re-transplant candidates.

    PubMed

    Arnold, Marie-Luise; Fuernrohr, Barbara G; Weiß, Katrin M; Harre, Ulrike; Wiesener, Michael S; Spriewald, Bernd M

    2015-10-01

    The family of Fc gamma receptors (FcγRs) is involved in mediating immunological effector functions. FcγRs are differentially expressed on immune cells and can act either activating or inhibitory, with FcγR2A belonging to the first group. The polymorphism H131R (rs1801274) in FCGR2A has been associated with acute rejection and can shift the overall balance between activating and inhibitory FcγRs. Anti-HLA allo-antibodies in transplant recipients have been identified as risk factor for organ survival after transplantation. In this study we genotyped FCGR2A H131R in 200 patients who had undergone kidney transplantation and experienced loss of graft function. FCGR2A polymorphism was related to graft survival and anti-HLA antibodies. Graft survival was calculated as the time interval between transplantation and return to chronic dialysis after transplantation. The gene frequency of FCGR2A R/R131 was found significantly more often in patients with earlier (⩽60months) compared to patients with later (>60months) graft failure. Overall patients homozygous for R/R131 had a significantly shorter graft survival, compared to H/H131 or H/R131 which is even more pronounced, when anti-HLA antibodies were present. These data suggest, that FCGR2A polymorphisms constitute a risk factor for graft loss following kidney transplantation and that this effect is related to anti-HLA antibodies. PMID:26429312

  16. Fluorescence-based RT PCR analysis: determination of the ratio of soluble to membrane-bound forms of Fc gamma RIIA transcripts in hematopoietic cell lines.

    PubMed

    Keller, M A; Cassel, D L; Rappaport, E F; McKenzie, S E; Schwartz, E; Surrey, S

    1993-08-01

    We have developed a fluorescence-based RT PCR assay for determination of the ratio of two alternatively spliced transcripts in different cell types. Fluorescence detection, by an automated DNA sequencer, allows enhanced sensitivity and ease of data processing. PCR products are fluorescently tagged using a dye-labeled oligonucleotide primer during the PCR reaction. Assay conditions were first defined so that fluorescence intensity of the PCR products was linear with respect to input RNA and exponential relative to PCR cycle number. Sensitivity and reproducibility of detection were evaluated with serial dilutions of RT PCR reactions. We have applied this assay to an analysis of the lineage-specific expression of two human Fc gamma RIIA transcripts, Fc gamma RIIa1 and Fc gamma RIIa2, in different hematopoietic cell lines. Previously, we noted that when standard RT PCR conditions are used with primers that bracket the TM exon, the pattern of expression of these transcripts as assessed by ethidium bromide staining of agarose gels varied in different hematopoietic cell lineages. Using the fluorescence-based RT PCR method, we now confirm our previous findings and quantitate transcript ratios (Fc gamma RIIa2/Fc gamma RIIa1) in several hematopoietic cell lines. The ratio varies from 0.70 (41% Fc gamma RIIa2) in the erythroleukemic cell line HEL, to 0.14 (12% Fc gamma RIIa2) in the monocytic cell line U937, to 0.07 (6% Fc gamma RIIa2) in the multipotential cell line K562. This fluorescent RT PCR method provides a general approach to quantitating mRNA levels and ratios of PCR products in other gene systems.

  17. Functional co-localization of monocytic aminopeptidase N/CD13 with the Fc{gamma} receptors CD32 and CD64

    SciTech Connect

    Riemann, Dagmar; Wulfaenger, Jens

    2005-06-17

    Information about the function of aminopeptidase N/CD13 on monocytes is limited. In order to gain more insight into its interaction with other proteins, we have identified molecules that co-localize with the membrane ectoenzyme at the cell surface of monocytes. Using laser scanning and electron microscopy as well as fluorescence resonance energy transfer (FRET) measured by flow cytometry we show that monocytic CD13 co-localized with the Fc{gamma} receptor II/CD32 after Fc receptor ligation by a CD32-specific antibody. FRET was also observed between CD13 and the Fc{gamma} receptor I/CD64, but not with the myeloid marker CD33 representing a member of the sialoadhesin family. Our results imply a novel functional role of CD13 and Fc{gamma} receptors as members of a multimeric receptor complex. Further studies have to be done to elucidate common signaling pathways of these molecules.

  18. Fc gamma receptor IIb on target B cells promotes rituximab internalization and reduces clinical efficacy.

    PubMed

    Lim, Sean H; Vaughan, Andrew T; Ashton-Key, Margaret; Williams, Emily L; Dixon, Sandra V; Chan, H T Claude; Beers, Stephen A; French, Ruth R; Cox, Kerry L; Davies, Andrew J; Potter, Kathleen N; Mockridge, C Ian; Oscier, David G; Johnson, Peter W M; Cragg, Mark S; Glennie, Martin J

    2011-09-01

    The anti-CD20 mAb rituximab is central to the treatment of B-cell malignancies, but resistance remains a significant problem. We recently reported that resistance could be explained, in part, by internalization of rituximab (type I anti-CD20) from the surface of certain B-cell malignancies, thus limiting engagement of natural effectors and increasing mAb consumption. Internalization of rituximab was most evident in chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL), but the extent of internalization was heterogeneous within each disease. Here, we show that the inhibitory FcγRIIb on target B cells promotes this process and is largely responsible for the observed heterogeneity across a range of B-cell malignancies. Internalization correlated strongly with FcγRIIb expression on normal and malignant B cells, and resulted in reduced macrophage phagocytosis of mAb-coated targets. Furthermore, transfection of FcγRIIb into FcγRIIb negative Ramos cells increased internalization of rituximab in a dose-dependent manner. Target-cell FcγRIIb promoted rituximab internalization in a cis fashion and was independent of FcγRIIb on neighboring cells. It became phosphorylated and internalized along with CD20:anti-CD20 complexes before lysosomal degradation. In MCL patients, high FcγRIIb expression predicted less durable responses after rituximab-containing regimens. Therefore, target-cell FcγRIIb provides a potential biomarker of response to type I anti-CD20 mAb.

  19. Signal transduction by the CD2 antigen in T cells and natural killer cells: requirement for expression of a functional T cell receptor or binding of antibody Fc to the Fc receptor, Fc gamma RIIIA (CD16).

    PubMed

    Spruyt, L L; Glennie, M J; Beyers, A D; Williams, A F

    1991-12-01

    Crosslinking of CD2 antigen on T lymphocytes and natural killer (NK) cells leads to a rise in cytoplasmic-free Ca2+ concentration ([Ca2+]i). However, CD2 seems unlikely to interact directly with the second messenger pathways since signaling via CD2 is poor in T cells that lack the T cell receptor (TCR) and is absent in L cells or insect cells that express CD2. In contrast, NK cells that are also TCR- can be triggered via CD2, but it is unclear as to whether the CD16 Fc receptor (FcR) may facilitate this effect. The CD16 transmembrane molecule is expressed in a complex with the zeta homodimer or the zeta/gamma heterodimer and these dimers are also associated with the TCR complex. Thus, it seemed that zeta chains may provide the link between signaling on NK cells and T cells. This could be tested on TCR- cells since when CD16 is transfected into T cells it is expressed in a complex with TCR zeta homodimer or the zeta/gamma heterodimer. At first, potentiation of CD2 signaling was seen on TCR- Jurkat cells expressing CD16, but this was found to be dependent on trace levels (1%) of IgG in F(ab')2 antibody preparations. With pure F(ab')2, the effect was lost. Signaling on a rat NK cell line was also re-examined with F(ab')2 antibodies that had no IgG contamination, and again no signal transduction via CD2 was seen. We thus conclude that there is no clear evidence for potent signaling via CD2 on cells that lack a TCR complex and that TCR zeta chain expressed at the cell surface is not sufficient to potentiate signaling via CD2 as measured by an increase in [Ca2+]i.

  20. Signal transduction by the CD2 antigen in T cells and natural killer cells: requirement for expression of a functional T cell receptor or binding of antibody Fc to the Fc receptor, Fc gamma RIIIA (CD16)

    PubMed Central

    1991-01-01

    Crosslinking of CD2 antigen on T lymphocytes and natural killer (NK) cells leads to a rise in cytoplasmic-free Ca2+ concentration ([Ca2+]i). However, CD2 seems unlikely to interact directly with the second messenger pathways since signaling via CD2 is poor in T cells that lack the T cell receptor (TCR) and is absent in L cells or insect cells that express CD2. In contrast, NK cells that are also TCR- can be triggered via CD2, but it is unclear as to whether the CD16 Fc receptor (FcR) may facilitate this effect. The CD16 transmembrane molecule is expressed in a complex with the zeta homodimer or the zeta/gamma heterodimer and these dimers are also associated with the TCR complex. Thus, it seemed that zeta chains may provide the link between signaling on NK cells and T cells. This could be tested on TCR- cells since when CD16 is transfected into T cells it is expressed in a complex with TCR zeta homodimer or the zeta/gamma heterodimer. At first, potentiation of CD2 signaling was seen on TCR- Jurkat cells expressing CD16, but this was found to be dependent on trace levels (1%) of IgG in F(ab')2 antibody preparations. With pure F(ab')2, the effect was lost. Signaling on a rat NK cell line was also re-examined with F(ab')2 antibodies that had no IgG contamination, and again no signal transduction via CD2 was seen. We thus conclude that there is no clear evidence for potent signaling via CD2 on cells that lack a TCR complex and that TCR zeta chain expressed at the cell surface is not sufficient to potentiate signaling via CD2 as measured by an increase in [Ca2+]i. PMID:1683892

  1. Fc Gamma Receptor 3A Polymorphism and Risk for HIV-Associated Cryptococcal Disease

    PubMed Central

    Rohatgi, Soma; Gohil, Shruti; Kuniholm, Mark H.; Schultz, Hannah; Dufaud, Chad; Armour, Kathryn L.; Badri, Sheila; Mailliard, Robbie B.; Pirofski, Liise-anne

    2013-01-01

    ABSTRACT Cryptococcus neoformans is one of the most common causes of fungal disease in HIV-infected persons, but not all of those who are infected develop cryptococcal disease (CD). Although CD4+ T cell deficiency is a risk factor for HIV-associated CD, polymorphisms of phagocytic Fc gamma receptors (FCGRs) have been linked to CD risk in HIV-uninfected persons. To investigate associations between FCGR2A 131 H/R and FCGR3A 158 F/V polymorphisms and CD risk in HIV-infected persons, we performed PCR-based genotyping on banked samples from 164 men enrolled in the Multicenter AIDS Cohort Study (MACS): 55 who were HIV infected and developed CD and a matched control group of 54 who were HIV infected and 55 who were HIV uninfected. Using additive and allelic statistical models for analysis, the high-affinity FCGR3A 158V allele was significantly associated with CD status after adjusting for race/ethnicity (odds ratio [OR], 2.1; P = 0.005), as was the FCGR3A 158 VV homozygous genotype after adjusting for race/ethnicity, rate of CD4+ T cell decline, and nadir CD4+ T cell count (OR, 21; P = 0.005). No associations between CD and FCGR2A 131 H/R polymorphism were identified. In binding studies, human IgG (hIgG)-C. neoformans complexes exhibited more binding to CHO-K1 cells expressing FCGR3A 158V than to those expressing FCGR3A 158F, and in cytotoxicity assays, natural killer (NK) cells expressing FCGR3A 158V induced more C. neoformans-infected monocyte cytotoxicity than those expressing FCGR3A 158F. Together, these results show an association between the FCGR3A 158V allele and risk for HIV-associated CD and suggest that this polymorphism could promote C. neoformans pathogenesis via increased binding of C. neoformans immune complexes, resulting in increased phagocyte cargo and/or immune activation. PMID:23982074

  2. Immunoglobulin Fc gamma receptor promotes immunoglobulin uptake, immunoglobulin-mediated calcium increase, and neurotransmitter release in motor neurons

    NASA Technical Reports Server (NTRS)

    Mohamed, Habib A.; Mosier, Dennis R.; Zou, Ling L.; Siklos, Laszlo; Alexianu, Maria E.; Engelhardt, Jozsef I.; Beers, David R.; Le, Wei-dong; Appel, Stanley H.

    2002-01-01

    Receptors for the Fc portion of immunoglobulin G (IgG; FcgammaRs) facilitate IgG uptake by effector cells as well as cellular responses initiated by IgG binding. In earlier studies, we demonstrated that amyotrophic lateral sclerosis (ALS) patient IgG can be taken up by motor neuron terminals and transported retrogradely to the cell body and can alter the function of neuromuscular synapses, such as increasing intracellular calcium and spontaneous transmitter release from motor axon terminals after passive transfer. In the present study, we examined whether FcgammaR-mediated processes can contribute to these effects of ALS patient immunoglobulins. F(ab')(2) fragments (which lack the Fc portion) of ALS patient IgG were not taken up by motor axon terminals and were not retrogradely transported. Furthermore, in a genetically modified mouse lacking the gamma subunit of the FcR, the uptake of whole ALS IgG and its ability to enhance intracellular calcium and acetylcholine release were markedly attenuated. These data suggest that FcgammaRs appear to participate in IgG uptake into motor neurons as well as IgG-mediated increases in intracellular calcium and acetylcholine release from motor axon terminals. Copyright 2002 Wiley-Liss, Inc.

  3. Opsonin-independent ligation of Fc gamma receptors. The 3G8-bearing receptors on neutrophils mediate the phagocytosis of concanavalin A- treated erythrocytes and nonopsonized Escherichia coli

    PubMed Central

    1987-01-01

    We report that phagocytosis by human neutrophils of Con A-treated erythrocytes (E-Con A) and nonopsonized Escherichia coli with mannose- binding adhesions is mediated by the Fc gamma receptor bearing the 3G8 epitope. Modulation of Fc receptors by pretreating with aggregated-IgG or with 3G8 anti-Fc gamma receptor mAb markedly inhibited internalization of E-Con A and E. coli without altering their cell surface attachment. Phagocytosis of these probes was specifically blocked by alpha-methylmannoside and D-mannose and not by other monosaccharides. Thus, recognition of E-Con A and E. coli by the Fc receptor is dependent upon the mannose-specific interaction with lectin or lectin-like adhesions. These data demonstrate that ligands other than the classical IgG opsonins can bind to classical immune receptors for IgG through lectin-carbohydrate interactions. PMID:2445895

  4. Lipid rafts facilitate the interaction of PECAM-1 with the glycoprotein VI-FcR gamma-chain complex in human platelets.

    PubMed

    Lee, Fiona A; van Lier, Marjolijn; Relou, Ingrid A M; Foley, Loraine; Akkerman, Jan-Willem N; Heijnen, Harry F G; Farndale, Richard W

    2006-12-22

    Glycoprotein (GP) VI, the main signaling receptor for collagen on platelets, is expressed in complex with the FcR gamma-chain. The latter contains an immunoreceptor tyrosine-based activation motif, which becomes phosphorylated, initiating a signaling cascade leading to the rapid activation and aggregation of platelets. Previous studies have shown that signaling by immunoreceptor tyrosine-based activation motif-containing receptors is counteracted by signals from receptors with immunoreceptor tyrosine-based inhibitory motifs. Here we show, by immunoprecipitation, that the GPVI-FcR gamma-chain complex associates with the immunoreceptor tyrosine-based inhibitory motif-containing receptor, PECAM-1. In platelets stimulated with collagen-related peptide (CRP-XL), tyrosine phosphorylation of PECAM-1 precedes that of the FcR gamma-chain, implying direct regulation of the former. The GPVI-FcR gamma-chain complex and PECAM-1 were present in both lipid raft and soluble fractions in human platelets; this distribution was unaltered by activation with CRP-XL. Their association occurred in lipid rafts and was lost after lipid raft depletion using methyl-beta-cyclodextrin. We propose that lipid raft clustering facilitates the interaction of PECAM-1 with the GPVI-FcR gamma-chain complex, leading to the down-regulation of the latter. PMID:17068334

  5. Fc Gamma Receptor Signaling in Mast Cells Links Microbial Stimulation to Mucosal Immune Inflammation in the Intestine

    PubMed Central

    Chen, Xiao; Feng, Bai-Sui; Zheng, Peng-Yuan; Liao, Xue-Qing; Chong, Jasmine; Tang, Shang-Guo; Yang, Ping-Chang

    2008-01-01

    Microbes and microbial products are closely associated with the pathogenesis of inflammatory bowel disease (IBD); however, the mechanisms behind this connection remain unclear. It has been previously reported that flagellin-specific antibodies are increased in IBD patient sera. As mastocytosis is one of the pathological features of IBD, we hypothesized that flagellin-specific immune responses might activate mast cells that then contribute to the initiation and maintenance of intestinal inflammation. Thirty-two colonic biopsy samples were collected from IBD patients. A flagellin/flagellin-specific IgG/Fc gamma receptor I complex was identified on biopsied mast cells using both immunohistochemistry and co-immunoprecipitation experiments; this complex was shown to co-localize on the surfaces of mast cells in the colonic mucosa of patients with IBD. In addition, an ex vivo study showed flagellin-IgG was able to bind to human mast cells. These cells were found to be sensitized to flagellin-specific IgG; re-exposure to flagellin induced the mast cells to release inflammatory mediators. An animal model of IBD was then used to examine flagellin-specific immune responses in the intestine. Mice could be sensitized to flagellin, and repeated challenges with flagellin induced an IBD-like T helper 1 pattern of intestinal inflammation that could be inhibited by pretreatment with anti-Fc gamma receptor I antibodies. Therefore, flagellin-specific immune responses activate mast cells in the intestine and play important roles in the pathogenesis of intestinal immune inflammation. PMID:18974296

  6. Protein kinase activity associated with Fc. gamma. /sub 2a/ receptor of a murine macrophage like cell line, P388D/sub 1/

    SciTech Connect

    Hirata, Y.; Suzuki, T.

    1987-12-15

    The properties of protein kinase activity associated with Fc receptor specific for IgG/sub 2a/(Fc..gamma../sub 2a/R) of a murine macrophage like cell line, P388D/sub 1/, were investigated. IgG/sub 2a/-binding protein isolated from the detergent lysate of P388D/sub 1/ cells by affinity chromatography of IgG-Sepharose was found to contain four distinct proteins of M/sub r/ 50,000, 43,000, 37,000, and 17,000, which could be autophosphorylated upon incubation with (..gamma..-/sup 32/P)ATP. The autophosphorylation of Fc..gamma../sub 2a/ receptor complex ceased when exogenous phosphate acceptors (casein or histone) were added in the reaction mixture. Phosphorylation of casein catalyzed by Fc..gamma../sub 2a/ receptor complex was dependent on casein concentration, increased with time or temperature, was dependent on the concentration of ATP and Mg/sup 2 +/, and was maximum at pH near 8. Casein phosphorylation was significantly inhibited by a high concentration of Mn/sup 2 +/ or KCl or by a small amount of heparin and was enhanced about 2-fold by protamine. Casein kinase activity associated with Fc..gamma../sub 2a/ receptor used ATP as substrate with an apparent K/sub m/ of 2 ..mu..M as well as GTP with an apparent K/sub m/ of 10 ..mu..M. Prior heating (60/sup 0/C for 15 min) or treatment with protease (trypsin or Pronase) of Fc..gamma../sub 2a/ receptor complex almost totally abolished casein kinase activity. Thin-layer chromatography of a partial acid hydrolysate of the phosphorylated casein showed that the site of phosphorylation is at a seryl residue. These results suggest that Fc..gamma../sub 2//sub a/ receptor forms a molecule complex with protein kinase, whose characteristics resemble those of type II casein kinase but are different from those of cyclic nucleotide dependent protein kinase or from those of C protein kinase.

  7. Impact of Fc gamma-receptor polymorphisms on the response to rituximab treatment in children and adolescents with mature B cell lymphoma/leukemia.

    PubMed

    Burkhardt, Birgit; Yavuz, Deniz; Zimmermann, Martin; Schieferstein, Jutta; Kabickova, Edita; Attarbaschi, Andishe; Lisfeld, Jasmin; Reiter, Alfred; Makarova, Olga; Worch, Jennifer; Bonn, Bettina R; Damm-Welk, Christine

    2016-09-01

    Recent studies in adult lymphoma patients have indicated a correlation between polymorphisms of Fc gamma-receptors (FcγRs, encoded by the respective FCGR genes) and the response to rituximab treatment. In vitro, cells expressing FcγRIIIa-158V mediate antibody-dependent cellular cytotoxicity (ADCC) more efficiently than cells expressing FcγRIIIa-158F. The impact of the FCGR2A-131HR polymorphism is unclear. In this study, the FCGR polymorphisms FCGR3A-158VF and FCGR2A-131HR were analyzed in pediatric patients with mature aggressive B cell non-Hodgkin lymphoma/leukemia (B-NHL). Pediatric patients received a single dose of rituximab monotherapy. Response was evaluated on day 5 followed by standard chemotherapy for B-NHL. Among 105 evaluable patients, a response to rituximab was observed in 21 % of those homozygous for FcγRIIa-131RR (5/24) compared to 48 % of patients who were HH and HR FcγRIIa-131 allele carriers (18/34 and 21/47, respectively; p = 0.044). Among patients with the FCGR3A-158 polymorphism, those homozygous for the FF genotype had a significantly favorable rituximab response rate of 59 % (22/37) compared to 32 % in patients who were FcγRIIIa-158VV and FcγRIIIa-VF allele carriers (2/9 and 20/59, respectively; p = 0.022). A stringent phase II response evaluation of children and adolescents with B-NHL after one dose of rituximab monotherapy showed a significant association between the rituximab response rate and FCGR polymorphisms. These findings support the hypothesis that FCGR polymorphisms represent patient-specific parameters that influence the response to rituximab. PMID:27376362

  8. Increased expression of CCL18, CCL19, and CCL17 by dendritic cells from patients with rheumatoid arthritis, and regulation by Fc gamma receptors

    PubMed Central

    Radstake, T; van der Voort, R; ten, B; de Waal, Malefijt M; Looman, M; Figdor, C; van den Berg, W B; Barrera, P; Adema, G

    2005-01-01

    Background: Dendritic cells (DC) have a role in the regulation of immunity and tolerance, attracting inflammatory cells by the production of various chemokines (CK). Fc gamma receptors (FcγR) may be involved in regulation of the DC function. Objective: To assess the expression of CK by immature (iDC) and mature DC (mDC) and its regulation by FcγR in patients with RA and healthy donors (HC). Methods: Expression of CK by DC from patients with RA and from HC was determined by real time quantitative PCR and ELISA. DC were derived from monocytes following standardised protocols. To study the potential regulation by FcγR, iDC were stimulated with immune complexes (IC) during lipopolysaccharide (LPS) induced maturation. The presence of CK was studied in synovial tissue from patients with RA, osteoarthritis, and healthy subjects by RT-PCR and immunohistochemistry. Results: iDC from patients with RA had markedly increased mRNA levels of the CK CCL18 and CXCL8. Upon maturation with LPS, expression of CCL18, CCL19, CXCL8, CCL3, and CCL17 increased dramatically, reaching significantly higher levels in patients with RA. Monocytes failed to express these CK, except for CXCL8 and CCL3. IC-mediated triggering of the FcγR on DC from patients with highly active RA down regulated all CK, whereas the reverse was seen when DC from patients with low disease activity and healthy donors were stimulated. CCL18 was significantly increased in RA synovial tissue. Conclusion: Increased CK expression by DC was found in patients with RA. This expression is partly regulated by FcγR triggering and results in an inhibitory DC subtype in RA upon FcγR-mediated triggering. PMID:15331393

  9. Intraperitoneal Immunization with Cry1Ac Protoxin from Bacillus thuringiensis Provokes Upregulation of Fc-Gamma-II/and Fc-Gamma-III Receptors Associated with IgG in the Intestinal Epithelium of Mice.

    PubMed

    Moreno-Fierros, L; Verdín-Terán, S L; García-Hernández, A L

    2015-07-01

    In humans, intestinal epithelial FcRn is expressed throughout life and mediates the bidirectional transport of IgG, but in mice, it is markedly expressed in neonatal intestine. In adults, its expression is only faintly upregulated after intestinal IgG induction such as that elicited by i.p. immunization with Cry1Ac protoxin (pCry1Ac) Bacillus thuringiensis. This led us to suggest that additional Fcγ receptors (Fcγ-R) may be participating in epithelial IgG uptake. So, first we determined whether CD16/32 [an epitope shared by Fcγ-RII (CD32) and Fcγ-RIII (CD16)] was expressed in the intestinal epithelia of mice. Using confocal microscopy and flow cytometry, we detected co-localization of IgG and CD16/32 in epithelial cells, whose frequency was increased by immunization with pCry1Ac. Western blot and cross-immunoprecipitation results with anti-CD16/32 and IgG antibodies in epithelial cell extracts suggested that epithelial cells bear both Fcγ-RII and Fcγ-RIII and contained IgG associated with Fcγ-RII/RIII. Using anti-CD32 and anti-CD16 antibodies, we confirmed by Western blot, confocal microscopy and flow cytometry that both Fcγ-RII and Fcγ-RIII were expressed and suggested that upregulation occurred upon immunization in intestinal epithelia. Finally, we examined the in vitro effect of anti-CD16/32, anti-CD16 and anti-CD32 antibodies on IgG uptake and transport by intestinal epithelial cells and found that it was partially reduced. Although further studies are still required, our results suggest that Fcγ-RII and Fcγ-RIII might participate in the uptake and/or transport of IgG through the intestinal epithelia of adult mice. PMID:25904149

  10. Evaluation of the Combined Effects of Gamma Radiation and High Dietary Iron on Peripheral Leukocyte Distribution and Function

    NASA Technical Reports Server (NTRS)

    Crucian, Brian E.; Morgan, Jennifer L. L.; Quiriarte, Heather A.; Sams, Clarence F.; Smith, Scott M.; Zwart, Sara R.

    2011-01-01

    NASA is concerned with the health risks to astronauts, particularly those risks related to radiation exposure. Both radiation and increased iron stores can independently increase oxidative damage, resulting in protein, lipid and DNA oxidation. Oxidative stress increases the risk of many health problems including cancer, cataracts, and heart disease. This study, a subset of a larger interdisciplinary investigation of the combined effect of iron overload on sensitivity to radiation injury, monitored immune parameters in the peripheral blood of rats subjected to gamma radiation, high dietary iron or both. Specific immune measures consisted of (A) peripheral leukocyte distribution; (B) plasma cytokine levels; (C) cytokine production profiles following whole blood stimulation of either T cells or monocytes.

  11. RSV neutralization by palivizumab, but not by monoclonal antibodies targeting other epitopes, is augmented by Fc gamma receptors.

    PubMed

    van Mechelen, Lenny; Luytjes, Willem; de Haan, Cornelis A M; Wicht, Oliver

    2016-08-01

    Palivizumab efficiently blocks respiratory syncytial virus (RSV) infection in vitro. However, virus neutralization assays generally omit Fc region-mediated effects. We investigated the neutralization activity of RSV-specific monoclonal antibodies on cells with Fc receptors. Subneutralizing concentrations of antibodies resulted in antibody-dependent enhancement of RSV infection in monocytic cells. Contrary to antibodies targeting other epitopes, the neutralization by palivizumab was augmented in cells with Fc receptors. This unrecognized characteristic of palivizumab may be relevant for its performance in vivo.

  12. RSV neutralization by palivizumab, but not by monoclonal antibodies targeting other epitopes, is augmented by Fc gamma receptors.

    PubMed

    van Mechelen, Lenny; Luytjes, Willem; de Haan, Cornelis A M; Wicht, Oliver

    2016-08-01

    Palivizumab efficiently blocks respiratory syncytial virus (RSV) infection in vitro. However, virus neutralization assays generally omit Fc region-mediated effects. We investigated the neutralization activity of RSV-specific monoclonal antibodies on cells with Fc receptors. Subneutralizing concentrations of antibodies resulted in antibody-dependent enhancement of RSV infection in monocytic cells. Contrary to antibodies targeting other epitopes, the neutralization by palivizumab was augmented in cells with Fc receptors. This unrecognized characteristic of palivizumab may be relevant for its performance in vivo. PMID:27185625

  13. Subclass specificity of the Fc receptor for human IgG on K562.

    PubMed

    Chiofalo, M S; Teti, G; Goust, J M; Trifiletti, R; La Via, M F

    1988-07-01

    The erythroleukemic cell line K562 bears a 40-kDa Fc receptor (Fc gamma RII) serologically related to and with a similar molecular weight as the Fc gamma R present on a broad range of leukocytes. The human IgG subclass specificity of the Fc gamma R on K562 was investigated using IgG aggregates of defined size, obtained from purified human myeloma proteins. The monoclonal antibody IV.3, which reacts with the Fc gamma RII present on various cell types, totally prevented binding of 125I-IgG2 trimers to K562. Experiments with radiolabeled IgG2 trimers showed that K562 cells bound a mean of 156,764 +/- 9895 molecules per cell with an association constant (Ka) of 1.8 +/- 0.7 X 10(8) M-1. Similar results were obtained with IgG3 oligomers. IgG3 and IgG2 trimers were about two- to threefold more effective in inhibiting binding of 125I-IgG2 trimers to K562 than IgG1 and IgG4 trimers. These results were confirmed by inhibition experiments using IgG monomers. The subclass specificity of the Fc gamma RII on K562 (i.e., IgG2 = IgG3 greater than IgG1 = IgG4) is quite distinct from the one reported for the Fc gamma RI and III of human cells (i.e., IgG1 = IgG3 greater than IgG4 and IgG2). PMID:2968843

  14. Deregulated Fcγ receptor expression in patients with CIDP

    PubMed Central

    Quast, Isaak; Cueni, Flavio; Nimmerjahn, Falk; Tackenberg, Björn

    2015-01-01

    Objective: To evaluate the expression of activating and inhibitory Fc-gamma receptors (FcγRs) before and during clinically effective therapy with IV immunoglobulin (IVIg) in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). Methods: Peripheral blood leukocyte subsets, including classical CD14highCD16− and nonclassical inflammatory CD14lowCD16+ monocytes as well as naive CD19+CD27− and memory CD19+CD27+ B cells, were obtained at baseline and monitored at 2 and 4–8 weeks after initiation of IVIg therapy. Results: Compared with healthy donors matched by age and sex, patients with CIDP showed increased expression levels of the activating high-affinity FcγR1 on CD14highCD16− (p < 0.001) and CD14lowCD16+ monocytes (p < 0.001). Expression of the activating low-affinity FcγRIIA was increased on CD14lowCD16+ monocytes (p = 0.023). Conversely, expression of the inhibitory FcγRIIB was reduced on naive (p = 0.009) and memory (p = 0.002) B cells as well as on CD14highCD16− monocytes (p = 0.046). Clinically effective IVIg therapy partially restored deregulated FcγR expression on B cell subsets and monocytes. Conclusions: The FcγR regulatory system is disturbed in patients with CIDP. Balancing activating vs inhibitory FcγR expression might provide a clinical benefit for patients with CIDP. PMID:26380354

  15. Fc gamma receptor type III (CD16) is included in the zeta NK receptor complex expressed by human natural killer cells.

    PubMed Central

    Anderson, P; Caligiuri, M; O'Brien, C; Manley, T; Ritz, J; Schlossman, S F

    1990-01-01

    We recently reported that CD3- natural killer (NK) cells express the zeta chain of the T-cell receptor complex (zeta NK) in association with higher molecular weight structures whose expression differs between individual NK cell clones. Because NK cell cytolytic activity is known to be triggered by perturbation of the type III Fc gamma receptor (CD16), we sought to determine whether this activating molecule is included in the zeta NK molecular complex. Biochemical evidence for a physical association between CD16 and zeta NK was obtained by comparing immunoprecipitates formed using monoclonal antibodies reactive with each of these molecules by SDS/polyacrylamide gel electrophoresis, immunoblotting, and peptide mapping. In both clonal and polyclonal populations of CD3- NK cells, CD16 and zeta NK specifically associated with one another. Functional evidence for a specific association between CD16 and zeta NK in intact cells was obtained by demonstrating a coordinate down-modulation of both of these molecules induced by either phorbol 12-myristate 13-acetate or monoclonal antibodies reactive with CD16. Our results suggest that Fc gamma receptor type III (CD16) is included in the zeta NK complex and that this complex is likely to play an important role in NK cell activation. Images PMID:2138330

  16. Inhibition of th17 cells and promotion of tregs in fc gamma chain-deficient mice contributes to the attenuated atherosclerotic lesions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The presence of anti-oxLDL IgG is well documented in clinical and animal studies. However, the role for Fc Rs to the progression of atherosclerosis has not been studied in detail. In the present study, we investigated the role for activating Fc R in the progression of atherosclerosis using apoE-Fc -...

  17. IFN-gamma and prostaglandin E2 inhibit IL-4-induced expression of Fc epsilon R2/CD23 on B lymphocytes through different mechanisms without altering binding of IL-4 to its receptor

    SciTech Connect

    Galizzi, J.P.; Cabrillat, H.; Rousset, F.; Menetrier, C.; de Vries, J.E.; Banchereau, J.

    1988-09-15

    Human rIL-4 specifically induces the expression of the low affinity receptor for IgE (Fc epsilon R2/CD23) on normal B cells and on the Burkitt lymphoma cell line Jijoye. IL-4 does not induce the generation of the second messenger cAMP in Jijoye cells. PGE2 (at 10(-7) M) was found to inhibit by 50% the IL-4 mediated Fc epsilon R2/CD23 induction on Jijoye cells. The PGE2 half maximum inhibitory concentration (1 nM) was comparable to that inducing a half maximal increase of intracellular cAMP (4nM PGE2). 8-bromo-cAMP (10(-3) M), forskolin (10(-5) M), and cholera toxin (100 ng/ml), which increase intracellular cAMP levels, also inhibited by 40 to 80% the IL-4 induced Fc epsilon R2/CD23 expression on Jijoye cells. PGE2 8-bromo-cAMP, forskolin, and cholera toxin also inhibited the IL-4-induced Fc epsilon R2/CD23 expression on normal B lymphocytes. Taken together these data suggest that PGE2 inhibits the IL-4 induced Fc epsilon R2/CD23 through an increase of intracellular cAMP. In contrast, IFN-gamma, which strongly inhibits IL-4-mediated Fc epsilon R2/CD23 expression on Jijoye cells, did not increase intracellular cAMP levels and thus probably acts through another mechanism. IFN-gamma and PGE2 did not inhibit binding of IL-4 to its receptor. It could be excluded that IFN-gamma and PGE2 were acting via an alteration/desensitization of the IL-4R inasmuch as 24 h pre-incubation of Jijoye cells with these agents affected neither the affinity of 125I-IL-4 for its receptor (Kd = 0.8 to 1.5 x 10(-10) M) nor the maximal number of binding sites per Jijoye cells (Bmax = 390 to 550). Furthermore, IFN-gamma and PGE2 did not affect the internalization and degradation of 125I-IL-4. These data demonstrate that PGE2 and IFN-gamma inhibit the IL-4-mediated induction of Fc epsilon R2/CD23 on B lymphocytes via different mechanisms that do not alter the interaction of IL-4 with its receptor.

  18. Susceptibility to dengue hemorrhagic fever in vietnam: evidence of an association with variation in the vitamin d receptor and Fc gamma receptor IIa genes.

    PubMed

    Loke, Hsin; Bethell, Delia; Phuong, Cao Xuan Thanh; Day, Nick; White, Nicholas; Farrar, Jeremy; Hill, Adrian

    2002-07-01

    Dengue is an increasingly important cause of morbidity and mortality in the tropics, with more than a billion people at risk each year. Immunologic enhancement is thought to contribute to disease pathogenesis. Only a very small proportion of infected individuals develop life-threatening dengue hemorrhagic fever (DHF). In a large case-control study with 400 DHF patients and 300 matched controls, we have assessed five polymorphic non-HLA host genetic factors that might influence susceptibility to DHF. The less frequent t allele of a variant at position 352 of the vitamin D receptor (VDR) gene was associated with resistance to severe dengue (P = 0.03). Homozygotes for the arginine variant at position 131 of the Fc gammaRIIA gene, who have less capacity to opsonize IgG2 antibodies, may also be protected from DHF (one-tailed P = 0.03). No associations were found with polymorphisms in the mannose binding lectin, interleukin-1 (IL-4), and IL-1 receptor antagonist genes. Further studies to confirm these associations are warranted.

  19. The extended hinge region of IgG3 is not required for high phagocytic capacity mediated by Fc gamma receptors, but the heavy chains must be disulfide bonded.

    PubMed

    Aase, A; Sandlie, I; Norderhaug, L; Brekke, O H; Michaelsen, T E

    1993-07-01

    Fc gamma receptor (Fc gamma R) phagocytosis and respiratory burst were induced by chimeric mouse-human anti-(4-hydroxy-5-iodo-3-nitrophenyl) acetyl IgG3 antibodies with mutations in hinge and/or in CH1 region. IgG3 mutants with different hinge length ranging from 47 to 0 amino acids, an IgG3 molecule with an artificial hinge of just one cysteine residue (HM-1), and two hybrid IgG3 molecules with IgG4 hinge or IgG4 CH1-hinge were tested. Using the monocytic cell line U937 as effector cells, the mutated IgG3 molecules were very similar, revealing high activity, while the IgG3/IgG4 hybrids revealed a slightly reduced activity. However, the hingeless (0-h) mutant was negative, except after interferon-gamma stimulation when it became slightly positive. Interestingly, HM-1 was as active as the IgG3 mutants. With polymorphonuclear leucocytes (PMN) as effector cells we obtained some day-to-day variations, but all the IgG3 mutants were highly active, with the two shortest hinge mutants somewhat less active. The IgG3/IgG4 hybrid molecules revealed an intermediate activity, while IgG4 wild-type and the 0-h mutant were negative. However, the HM-1 molecule revealed an activity similar to that of the IgG3 mutants. The phagocytic activity of U937 was inhibited by monomeric IgG, indicating the importance of Fc gamma RI. In contrast, with PMN both blockage of Fc gamma RII and cleavage of Fc gamma RIII were required to significantly reduce the phagocytosis and respiratory burst, thus showing that both receptors contribute to the effect. These results demonstrate that the extended IgG3 hinge region is not necessary for a high phagocytic activity and that the major structural importance of the hinge is to connect the two heavy chains in this region.

  20. Effects of prostaglandin E{sub 2} on the subcellular localization of Epac-1 and Rap1 proteins during Fc{gamma}-receptor-mediated phagocytosis in alveolar macrophages

    SciTech Connect

    Brock, Thomas G.; Serezani, Carlos H.; Carstens, Jennifer K.; Peters-Golden, Marc; Aronoff, David M.

    2008-01-15

    Recent studies have demonstrated a central role for the exchange protein activated by cAMP (Epac) in the inhibition of Fc{gamma}-receptor-mediated phagocytosis and bacterial killing by prostaglandin E{sub 2} (PGE{sub 2}) in macrophages. However, the subcellular localization of Epac, and its primary target Rap1, has yet to be determined in primary macrophages. Therefore, we used immunofluorescent techniques and phagosome isolation to localize Epac-1 and Rap1 in alveolar macrophages. Epac-1 was predominantly expressed on punctate and tubular membranes throughout the cell body; on the plasma membrane; and co-localized with microtubule organizing centers (MTOCs). Rap1 was abundant on punctate membranes, less abundant on plasma membrane, and also found on MTOCs. Following PGE{sub 2} treatment, Epac-1, but not Rap1, accumulated on the nuclear envelope and disappeared from MTOCs. By immunofluorescent microscopy, both Epac-1 and Rap1 were seen to associate with phagosomes containing IgG-opsonized beads, but this association appeared weak, as we failed to observe such interactions in phagosomes isolated from cells at various time points after bead ingestion. Strikingly, however, Epac-1, but not Rap1, appeared to accumulate on maturing phagosomes, but only after PGE{sub 2} treatment (or treatment with a selective Epac-1 agonist). This association was confirmed in isolated phagosome preparations. The changes in Epac-1 localization were too slow to account for the inhibitory effects of PGE{sub 2} on phagocytosis. However, the appearance of Epac-1 on late phagosomes following PGE{sub 2} treatment might be important for suppressing H{sub 2}O{sub 2} production and inhibiting the killing of intraphagosomal pathogens. The absence of Rap1 on late phagosomes suggests that the effect of Epac-1 might not require Rap1.

  1. Regulation of macrophage Fc receptor expression and phagocytosis by histidine-rich glycoprotein.

    PubMed Central

    Chang, N S; Leu, R W; Rummage, J A; Anderson, J K; Mole, J E

    1992-01-01

    Regulation of macrophage Fc receptor (Fc gamma R)-mediated phagocytic function by histidine-rich glycoprotein (HRG) was investigated. Pretreatment of oil-elicited inflammatory mouse peritoneal macrophages with HRG for 1-3 hr increased their Fc gamma R-mediated binding and phagocytosis of IgG-opsonized sheep erythrocyte conjugates (EA). A significant reduction of Fc gamma R-dependent EA binding and phagocytosis occurred after pretreatment of macrophages with HRG for more than 8 hr. These results indicate that HRG is capable of modulating Fc gamma R expression in a biphasic fashion, which directly affects the overall efficiency of phagocytosis. HRG differentially regulated the functions of Fc gamma R subclasses. For example, HRG reduced the efficiency of Fc gamma RII (Fc gamma 2b/gamma 1R)-dependent phagocytosis of erythrocytes conjugated with monoclonal IgG2b or IgG1 by macrophages pretreated with HRG for 24 hr. However, when similar studies were performed using erythrocytes coated with monoclonal IgG2a, HRG was less effective in inhibiting Fc gamma RI (Fc gamma 2aR)-dependent phagocytosis. As an HRG-binding glycosaminoglycan, heparin failed to block the regulatory function of HRG on macrophages. Similarly, interferon-gamma (IFN-gamma) was not capable of blocking the functional activity of HRG. These studies suggest that HRG regulates macrophage function via a novel pathway different from that of heparin or IFN-gamma. PMID:1493926

  2. A chimeric antibody with dual Fc regions (bisFabFc) prepared by manipulations at the IgG hinge.

    PubMed

    Stevenson, G T; Pindar, A; Slade, C J

    1989-03-01

    A new chimeric antibody for therapeutic use in human cancer is described. First the derivative FabFc was prepared by linking Fab' gamma from monoclonal antibody to Fc gamma from human normal IgG1. The bismaleimide linking agent forms a thioether bond with an SH group released by reduction of SS bonds in the hinge of each constituent. It follows that one of the original two SS bonds in the Fc hinge still has both its S atoms free, and this bond is reformed by thiol-disulphide interchange. The lone free SH in the Fc hinge can now be used to join two FabFc molecules through a similar bismaleimide linker to yield bisFabFc. As regards antibody activity against target cells, bisFabFc can be univalent, bivalent, or bispecific. Its juxtaposed dual Fc regions are designed to promote cooperative binding of effectors, and bisFabFc is indeed notably more powerful than its parent FabFc molecules in promoting complement lysis and antibody-dependent cellular cytotoxicity. However it is not possible at present to distinguish the separate contributions of Fc architecture, antibody affinity and other factors towards this improvement. In the present state of development a variety of FabFc against a given neoplasm may be prepared in high yield from mouse IgG1 and IgG2a antibodies, and when convenient dimerized to bisFabFc in any combination of specificities.

  3. Registration of 'FC1028', 'FC1037, 'FC1038' and, 'FC1036' multigerm sugarbeet germplasm with multiple disease resistances

    Technology Transfer Automated Retrieval System (TEKTRAN)

    FC1028’, ‘FC1036’, ‘FC1037’, and ‘FC1038’ (PI 665053, PI 665054, PI 665055, PI 665056) sugarbeet germplasms (Beta vulgaris L.) were released from 20111027, 09-FC1036, 20111025, and 04-FC1038 seed lots, respectively, and tested under the designations 04-FC1028; 05-, 06-, 07-, 08-, 09-FC1036; 04-FC10...

  4. Fc gamma receptor IIa-H131R polymorphism and malaria susceptibility in sympatric ethnic groups, Fulani and Dogon of Mali.

    PubMed

    Maiga, B; Dolo, A; Touré, O; Dara, V; Tapily, A; Campino, S; Sepulveda, N; Corran, P; Rockett, K; Clark, T G; Blomberg, M Troye; Doumbo, O K

    2014-01-01

    It has been previously shown that there are some interethnic differences in susceptibility to malaria between two sympatric ethnic groups of Mali, the Fulani and the Dogon. The lower susceptibility to Plasmodium falciparum malaria seen in the Fulani has not been fully explained by genetic polymorphisms previously known to be associated with malaria resistance, including haemoglobin S (HbS), haemoglobin C (HbC), alpha-thalassaemia and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Given the observed differences in the distribution of FcγRIIa allotypes among different ethnic groups and with malaria susceptibility that have been reported, we analysed the rs1801274-R131H polymorphism in the FcγRIIa gene in a study of Dogon and Fulani in Mali (n = 939). We confirm that the Fulani have less parasite densities, less parasite prevalence, more spleen enlargement and higher levels of total IgG antibodies (anti-CSP, anti-AMA1, anti-MSP1 and anti-MSP2) and more total IgE (P < 0.05) compared with the Dogon ethnic group. Furthermore, the Fulani exhibit higher frequencies of the blood group O (56.5%) compared with the Dogon (43.5%) (P < 0.001). With regard to the FcγRIIa polymorphism and allele frequency, the Fulani group have a higher frequency of the H allele (Fulani 0.474, Dogon 0.341, P < 0.0001), which was associated with greater total IgE production (P = 0.004). Our findings show that the FcγRIIa polymorphism might have an implication in the relative protection seen in the Fulani tribe, with confirmatory studies required in other malaria endemic settings.

  5. Fc gamma Receptor IIa-H131R Polymorphism and Malaria Susceptibility in Sympatric Ethnic Groups, Fulani and Dogon of Mali

    PubMed Central

    Maiga, B; Dolo, A; Touré, O; Dara, V; Tapily, A; Campino, S; Sepulveda, N; Corran, P; Rockett, K; Clark, T G; Troye Blomberg, M; Doumbo, O K

    2014-01-01

    It has been previously shown that there are some interethnic differences in susceptibility to malaria between two sympatric ethnic groups of Mali, the Fulani and the Dogon. The lower susceptibility to Plasmodium falciparum malaria seen in the Fulani has not been fully explained by genetic polymorphisms previously known to be associated with malaria resistance, including haemoglobin S (HbS), haemoglobin C (HbC), alpha-thalassaemia and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Given the observed differences in the distribution of FcγRIIa allotypes among different ethnic groups and with malaria susceptibility that have been reported, we analysed the rs1801274-R131H polymorphism in the FcγRIIa gene in a study of Dogon and Fulani in Mali (n = 939). We confirm that the Fulani have less parasite densities, less parasite prevalence, more spleen enlargement and higher levels of total IgG antibodies (anti-CSP, anti-AMA1, anti-MSP1 and anti-MSP2) and more total IgE (P < 0.05) compared with the Dogon ethnic group. Furthermore, the Fulani exhibit higher frequencies of the blood group O (56.5%) compared with the Dogon (43.5%) (P < 0.001). With regard to the FcγRIIa polymorphism and allele frequency, the Fulani group have a higher frequency of the H allele (Fulani 0.474, Dogon 0.341, P < 0.0001), which was associated with greater total IgE production (P = 0.004). Our findings show that the FcγRIIa polymorphism might have an implication in the relative protection seen in the Fulani tribe, with confirmatory studies required in other malaria endemic settings. PMID:24117665

  6. Swine leukocyte antigen-DQ expression and its regulation by interferon-gamma at the maternal-fetal interface in pigs.

    PubMed

    Kim, Mingoo; Seo, Heewon; Choi, Yohan; Shim, Jangsoo; Bazer, Fuller W; Ka, Hakhyun

    2012-02-01

    Successful pregnancy requires an appropriate intrauterine immune response to the conceptus, which is a semiallograft within the uterus. We reported that swine leukocyte antigen-DQA (SLA-DQA), a major histocompatibility complex (MHC) class II gene, is expressed in the uterine endometrium at the time of conceptus implantation in pigs. Because MHC molecules play critical roles in the immune system, SLA-DQ was hypothesized to be involved in immune regulation during pregnancy. Therefore, we examined expression of SLA-DQ in uterine endometrial tissues obtained during the estrous cycle and pregnancy. SLA-DQA and SLA-DQB mRNAs were detected as 1.3-kb and 1.2-kb bands, respectively. Real-time RT-PCR analysis indicated that SLA-DQA and SLA-DQB mRNA expression was affected by day and pregnancy status, with the highest expression on Day 15 of pregnancy. SLA-DQ was localized primarily to subepithelial stromal cells and endothelial cells of the uterus. Using endometrial explant cultures from Day 12 of the estrous cycle, we determined that expression of SLA-DQA and SLA-DQB mRNAs increased in response to interferon-gamma (IFNG), which is produced by pig conceptus trophectoderm between Days 14 and 18 of pregnancy. The abundance of SLA-DQ protein was less in endometria from gilts with conceptuses resulting from somatic cell nuclear transfer compared with endometria from gilts with conceptuses resulting from natural mating. These results support our hypothesis that SLA-DQ is expressed in response to IFNG from the conceptus, and likely regulates immune response at the maternal-fetal interface to support the maintenance of pregnancy in pigs.

  7. Registration of FC1018, FC1019, FC1020, and FC1022, Sugarbeet Multigerm Pollinator Germplasms with Disease Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    FC1018’, ‘FC1019’, ‘FC1020’, and ‘FC1022’ (PI 658059, PI 658060, PI 658061, PI 658062, respectively) sugarbeet germplasm (Beta vulgaris L.) were released in 2009 from 05-FC1018, 05-FC1019, 07-/08-FC1020 and 05-FC101022 seed lots, respectively, and tested under those designations. They were develo...

  8. T cell receptor complexes containing Fc epsilon RI gamma homodimers in lieu of CD3 zeta and CD3 eta components: a novel isoform expressed on large granular lymphocytes

    PubMed Central

    1992-01-01

    CD3 zeta and CD3 eta form disulfide-linked homo- or heterodimers important in targeting partially assembled Ti alpha-beta/CD3 gamma delta epsilon T cell receptor (TCR) complexes to the cell surface and transducing stimulatory signals after antigen recognition. Here we identify a new TCR isoform expressed on splenic CD2+, CD3/Ti alpha- beta+, CD4-, CD8-, CD16+, NK1.1+ mouse large granular lymphocytes (LGL), which are devoid of CD3 zeta and CD3 eta proteins. The TCRs of this subset contain homodimers of the gamma subunit of the high affinity receptor for IgE (Fc epsilon RI gamma) in lieu of CD3 zeta and/or CD3 eta proteins. The LGL display natural killer-like activity and are cytotoxic for B cell hybridomas producing anti-CD3 epsilon and anti-CD16 monoclonal antibodies, demonstrating the signaling capacity of both TCR and CD16 in this cell type. These findings provide evidence for an additional level of complexity of TCR signal transduction isoforms in naturally occurring T cell subsets. PMID:1530959

  9. The leukocytes.

    PubMed

    Zinkl, J G

    1981-05-01

    Dogs and cats respond to many diseases by changes in leukocyte numbers. Infectious diseases often cause leukocytosis due to neutrophilia. Left shift may accompany the leukocytosis, indicating that the marrow is mounting a response to the disease. Left shift also indicates that the marrow has fallen somewhat behind the needs of the animal. Degenerative left shift is considered a poor sign. Lymphopenia and eosinopenia also are found in infectious diseases. Lymphocytosis may occur during the recovery or if the disease becomes chronic. The nature and duration of the infection determine the magnitude of the monocyte response. It is erroneous to consider a disease chronic based only upon monocytosis. Trauma, autoimmunity, or any disease with significant tissue destruction can evoke a monocyte response. Leukopenias are relatively common in cats and are found with moderate frequency in dogs. Drugs, viral diseases (such as FeLV, feline enteritis, parvovirus), ehrlichiosis, and hereditary conditions may cause panleukopenias or single leukopenias. Occasionally leukocyte examination provides evidence of a specific etiology (such as with ehrlichiosis). Sometimes changes occur which, although not specific for a disease, may provide a strong evidence of a particular disease (such as in salmon poisoning). Leukocyte evaluation should include not only total count and differential count (with calculation of absolute numbers of the different cells) but also morphologic examination of the cells by qualified people. In many practices the only qualified person is the veterinarian.

  10. Structure of FcγRI in complex with Fc reveals the importance of glycan recognition for high-affinity IgG binding.

    PubMed

    Lu, Jinghua; Chu, Jonathan; Zou, Zhongcheng; Hamacher, Nels B; Rixon, Mark W; Sun, Peter D

    2015-01-20

    Fc gamma receptor I (FcγRI) contributes to protective immunity against bacterial infections, but exacerbates certain autoimmune diseases. The sole high-affinity IgG receptor, FcγRI plays a significant role in immunotherapy. To elucidate the molecular mechanism of its high-affinity IgG binding, we determined the crystal structure of the extracellular domains of human FcγRI in complex with the Fc domain of human IgG1. FcγRI binds to the Fc in a similar mode as the low-affinity FcγRII and FcγRIII receptors. In addition to many conserved contacts, FcγRI forms additional hydrogen bonds and salt bridges with the lower hinge region of Fc. Unique to the high-affinity receptor-Fc complex, however, is the conformation of the receptor D2 domain FG loop, which enables a charged KHR motif to interact with proximal carbohydrate units of the Fc glycans. Both the length and the charge of the FcγRI FG loop are well conserved among mammalian species. Ala and Glu mutations of the FG loop KHR residues showed significant contributions of His-174 and Arg-175 to antibody binding, and the loss of the FG loop-glycan interaction resulted in an ∼ 20- to 30-fold decrease in FcγRI affinity to all three subclasses of IgGs. Furthermore, deglycosylation of IgG1 resulted in a 40-fold loss in FcγRI binding, demonstrating involvement of the receptor FG loop in glycan recognition. These results highlight a unique glycan recognition in FcγRI function and open potential therapeutic avenues based on antibody glycan engineering or small molecular glycan mimics to target FcγRI for certain autoimmune diseases.

  11. Prevention of corticosteroid-induced suppression of human polymorphonuclear leukocyte-induced damage of Aspergillus fumigatus hyphae by granulocyte colony-stimulating factor and gamma interferon.

    PubMed Central

    Roilides, E; Uhlig, K; Venzon, D; Pizzo, P A; Walsh, T J

    1993-01-01

    Neutrophils (PMNs) are a critical line of defense against Aspergillus fumigatus infection. Increased frequency of invasive aspergillosis has been observed in patients receiving corticosteroids, suggesting a deleterious effect of these compounds on PMN antifungal function. To investigate this hypothesis and to determine the potential preventive utility of granulocyte colony-stimulating factor (G-CSF) and gamma interferon (IFN-gamma), the effects of hydrocortisone (HCS) and dexamethasone (DXS) on PMN-induced damage of Aspergillus fumigatus hyphae were studied with or without pretreatment of PMNs with G-CSF and IFN-gamma. PMNs treated with HCS (> or = 3,000 microM) or DXS (> or = 10 microM) during a 2-h colorimetric tetrazolium metabolic assay (using methylthiotetrazolium) showed suppressed percentage of hyphal damage (P < 0.02). In addition, both HCS (> or = 30 microM) and DXS (> or = 1 microM) significantly suppressed oxidative burst measured as superoxide anion release by PMNs in response to opsonized and nonopsonized hyphae as well as to N-formylmethionyl leucyl phenylalanine. Pretreatment of PMNs with G-CSF (4,000 U/ml) and/or IFN-gamma (100 and 1,000 U/ml) for 90 min prevented the suppression of hyphal damage that occurred in the presence of HCS (3,000 microM; P < 0.01) or DXS (10 microM; P < or = 0.001). G-CSF (4,000 U/ml) and IFN-gamma (100 U/ml) combined had an additive effect on increasing the antifungal activity of HCS-treated but not of DXS-treated PMNs compared with IFN-gamma alone (P = 0.015). Thus, these findings reveal that corticosteroids impair PMN function in response to A. fumigatus and that G-CSF and IFN-gamma prevent this impairment. PMID:7691757

  12. Simultaneous Targeting of FcγRs and FcαRI Enhances Tumor Cell Killing.

    PubMed

    Brandsma, Arianne M; Ten Broeke, Toine; Nederend, Maaike; Meulenbroek, Laura A P M; van Tetering, Geert; Meyer, Saskia; Jansen, J H Marco; Beltrán Buitrago, M Alejandra; Nagelkerke, Sietse Q; Németh, István; Ubink, Ruud; Rouwendal, Gerard; Lohse, Stefan; Valerius, Thomas; Leusen, Jeanette H W; Boross, Peter

    2015-12-01

    Efficacy of anticancer monoclonal antibodies (mAb) is limited by the exhaustion of effector mechanisms. IgG mAbs mediate cellular effector functions through FcγRs expressed on effector cells. IgA mAbs can also induce efficient tumor killing both in vitro and in vivo. IgA mAbs recruit FcαRI-expressing effector cells and therefore initiate different effector mechanisms in vivo compared with IgG. Here, we studied killing of tumor cells coexpressing EGFR and HER2 by the IgG mAbs cetuximab and trastuzumab and their IgA variants. In the presence of a heterogeneous population of effector cells (leukocytes), the combination of IgG and IgA mAbs to two different tumor targets (EGFR and HER2) led to enhanced cytotoxicity compared with each isotype alone. Combination of two IgGs or two IgAs or IgG and IgA against the same target did not enhance cytotoxicity. Increased cytotoxicity relied on the presence of both the peripheral blood mononuclear cell and the polymorphonuclear (PMN) fraction. Purified natural killer cells were only cytotoxic with IgG, whereas cytotoxicity induced by PMNs was strong with IgA and poor with IgG. Monocytes, which coexpress FcγRs and FcαRI, also displayed increased cytotoxicity by the combination of IgG and IgA in an overnight killing assay. Coinjection of cetuximab and IgA2-HER2 resulted in increased antitumor effects compared with either mAb alone in a xenograft model with A431-luc2-HER2 cells. Thus, the combination of IgG and IgA isotypes optimally mobilizes cellular effectors for cytotoxicity, representing a promising novel strategy to improve mAb therapy. PMID:26407589

  13. MHC class I-related neonatal Fc receptor for IgG is functionally expressed in monocytes, intestinal macrophages, and dendritic cells.

    PubMed

    Zhu, X; Meng, G; Dickinson, B L; Li, X; Mizoguchi, E; Miao, L; Wang, Y; Robert, C; Wu, B; Smith, P D; Lencer, W I; Blumberg, R S

    2001-03-01

    The neonatal Fc receptor (FcRn) for IgG, an MHC class I-related molecule, functions to transport IgG across polarized epithelial cells and protect IgG from degradation. However, little is known about whether FcRn is functionally expressed in immune cells. We show here that FcRn mRNA was identifiable in human monocytes, macrophages, and dendritic cells. FcRn heavy chain was detectable as a 45-kDa protein in monocytic U937 and THP-1 cells and in purified human intestinal macrophages, peripheral blood monocytes, and dendritic cells by Western blot analysis. FcRn colocalized in vivo with macrosialin (CD68) and Ncl-Macro, two macrophage markers, in the lamina propria of human small intestine. The heavy chain of FcRn was associated with the beta(2)-microglobulin (beta(2)m) light chain in U937 and THP-1 cells. FcRn bound human IgG at pH 6.0, but not at pH 7.5. This binding could be inhibited by human IgG Fc, but not Fab. FcRn could be detected on the cell surface of activated, but not resting, THP-1 cells. Furthermore, FcRn was uniformly present intracellularly in all blood monocytes and intestinal macrophages. FcRn was detectable on the cell surface of a significant fraction of monocytes at lower levels and on a small subset of tissue macrophages that expressed high levels of FcRn on the cell surface. These data show that FcRn is functionally expressed and its cellular distribution is regulated in monocytes, macrophages, and dendritic cells, suggesting that it may confer novel IgG binding functions upon these cell types relative to typical Fc gamma Rs: Fc gamma RI, Fc gamma RII, and Fc gamma RIII.

  14. Automated leukocyte recognition using fuzzy divergence.

    PubMed

    Ghosh, Madhumala; Das, Devkumar; Chakraborty, Chandan; Ray, Ajoy K

    2010-10-01

    This paper aims at introducing an automated approach to leukocyte recognition using fuzzy divergence and modified thresholding techniques. The recognition is done through the segmentation of nuclei where Gamma, Gaussian and Cauchy type of fuzzy membership functions are studied for the image pixels. It is in fact found that Cauchy leads better segmentation as compared to others. In addition, image thresholding is modified for better recognition. Results are studied and discussed.

  15. Targeting Sindbis virus-based vectors to Fc receptor-positive cell types

    SciTech Connect

    Klimstra, William B.; Williams, Jacqueline C.; Ryman, Kate D.; Heidner, Hans W. . E-mail: hans.heidner@utsa.edu

    2005-07-20

    Some viruses display enhanced infection for Fc receptor (FcR)-positive cell types when complexed with virus-specific immunoglobulin (Ig). This process has been termed antibody-dependent enhancement of viral infection (ADE). We reasoned that the mechanism of ADE could be exploited and adapted to target alphavirus-based vectors to FcR-positive cell types. Towards this goal, recombinant Sindbis viruses were constructed that express 1 to 4 immunoglobulin-binding domains of protein L (PpL) as N-terminal extensions of the E2 glycoprotein. PpL is a bacterial protein that binds the variable region of antibody kappa light chains from a range of mammalian species. The recombinant viruses incorporated PpL/E2 fusion proteins into the virion structure and recapitulated the species-specific Ig-binding phenotypes of native PpL. Virions reacted with non-immune serum or purified IgG displayed enhanced binding and ADE for several species-matched FcR-positive murine and human cell lines. ADE required virus expression of a functional PpL Ig-binding domain, and appeared to be Fc{gamma}R-mediated. Specifically, ADE did not occur with Fc{gamma}R-negative cells, did not require active complement proteins, and did not occur on Fc{gamma}R-positive murine cell lines when virions were bound by murine IgG-derived F(ab'){sub 2} fragments.

  16. Fc receptors and their influence on efficacy of therapeutic antibodies for treatment of viral diseases

    PubMed Central

    Chan, Kuan Rong; Ong, Eugenia Z; Mok, Darren ZL; Ooi, Eng Eong

    2015-01-01

    The lack of vaccines against several important viral diseases necessitates the development of therapeutics to save lives and control epidemics. In recent years, therapeutic antibodies have received considerable attention due to their good safety profiles and clinical success when used against viruses such as respiratory syncytial virus, Ebola virus and Hendra virus. The binding affinity of these antibodies can directly impact their therapeutic efficacy. However, we and others have also demonstrated that the subtype of Fc-gamma receptors (FcγRs) engaged influences the stoichiometric requirement for virus neutralization. Hence, the development of therapeutic antibodies against infectious diseases should consider the FcγRs engaged and Fc-effector functions involved. This review highlights the current state of knowledge about FcγRs and FcγR effector functions involved in virus neutralization, with emphasis on factors that can affect FcγR engagement. A better understanding of Fc-FcγR interactions during virus neutralization will allow development of therapeutic antibodies that are efficacious and can be administered with minimal side effects. PMID:26466016

  17. Engineered antibody Fc variant with selectively enhanced FcγRIIb binding over both FcγRIIa(R131) and FcγRIIa(H131).

    PubMed

    Mimoto, F; Katada, H; Kadono, S; Igawa, T; Kuramochi, T; Muraoka, M; Wada, Y; Haraya, K; Miyazaki, T; Hattori, K

    2013-10-01

    Engaging inhibitory FcγRIIb by Fc region has been recently reported to be an attractive approach for improving the efficacy of antibody therapeutics. However, the previously reported S267E/L328F variant with enhanced binding affinity to FcγRIIb, also enhances binding affinity to FcγRIIa(R131) allotype to a similar degree because FcγRIIb and FcγRIIa(R131) are structurally similar. In this study, we applied comprehensive mutagenesis and structure-guided design based on the crystal structure of the Fc/FcγRIIb complex to identify a novel Fc variant with selectively enhanced FcγRIIb binding over both FcγRIIa(R131) and FcγRIIa(H131). This novel variant has more than 200-fold stronger binding affinity to FcγRIIb than wild-type IgG1, while binding affinity to FcγRIIa(R131) and FcγRIIa(H131) is comparable with or lower than wild-type IgG1. This selectivity was achieved by conformational change of the C(H)2 domain by mutating Pro to Asp at position 238. Fc variant with increased binding to both FcγRIIb and FcγRIIa induced platelet aggregation and activation in an immune complex form in vitro while our novel variant did not. When applied to agonistic anti-CD137 IgG1 antibody, our variant greatly enhanced the agonistic activity. Thus, the selective enhancement of FcγRIIb binding achieved by our Fc variant provides a novel tool for improving the efficacy of antibody therapeutics.

  18. Engineered antibody Fc variant with selectively enhanced FcγRIIb binding over both FcγRIIaR131 and FcγRIIaH131

    PubMed Central

    Mimoto, F.; Katada, H.; Kadono, S.; Igawa, T.; Kuramochi, T.; Muraoka, M.; Wada, Y.; Haraya, K.; Miyazaki, T.; Hattori, K.

    2013-01-01

    Engaging inhibitory FcγRIIb by Fc region has been recently reported to be an attractive approach for improving the efficacy of antibody therapeutics. However, the previously reported S267E/L328F variant with enhanced binding affinity to FcγRIIb, also enhances binding affinity to FcγRIIaR131 allotype to a similar degree because FcγRIIb and FcγRIIaR131 are structurally similar. In this study, we applied comprehensive mutagenesis and structure-guided design based on the crystal structure of the Fc/FcγRIIb complex to identify a novel Fc variant with selectively enhanced FcγRIIb binding over both FcγRIIaR131 and FcγRIIaH131. This novel variant has more than 200-fold stronger binding affinity to FcγRIIb than wild-type IgG1, while binding affinity to FcγRIIaR131 and FcγRIIaH131 is comparable with or lower than wild-type IgG1. This selectivity was achieved by conformational change of the CH2 domain by mutating Pro to Asp at position 238. Fc variant with increased binding to both FcγRIIb and FcγRIIa induced platelet aggregation and activation in an immune complex form in vitro while our novel variant did not. When applied to agonistic anti-CD137 IgG1 antibody, our variant greatly enhanced the agonistic activity. Thus, the selective enhancement of FcγRIIb binding achieved by our Fc variant provides a novel tool for improving the efficacy of antibody therapeutics. PMID:23744091

  19. Expression and gene transcript of Fc receptors for IgG, HLA class II antigens and Langerhans cells in human cervico-vaginal epithelium.

    PubMed Central

    Hussain, L A; Kelly, C G; Fellowes, R; Hecht, E M; Wilson, J; Chapman, M; Lehner, T

    1992-01-01

    The mechanism of transmission of HIV from the male to the female genital tract or in the reverse order is not clear. CD4 glycoprotein is the receptor for HIV and Langerhans cells and the related dendritic cells could play a role in the initial transmission of HIV. Fc receptors (FcR) for IgG might be involved in antibody-mediated binding of HIV. We carried out an immunohistological study of normal human cervical and vaginal epithelia for the presence of CD4 glycoprotein, Langerhans cells and FcR to IgG. CD4+ glycoprotein was not found in the vaginal or cervical epithelium, with the exception of a few endocervical epithelial cells. A small number of CD4+ mononuclear cells were found in the endocervical epithelium of a third of the specimens but a large number of CD4+ cells was found in the submucosa of most of the cervical and vaginal specimens. Langerhans cells expressing CD4, HLA class II, Fc gamma R2 and Fc gamma R3 were detected in most vaginal, ectocervical and transformation zone epithelia and in 9/14 endocervical tissues. Fc gamma R3 was detected in about two-thirds of the columnar endocervical epithelium and the transformation zone. A smaller number of specimens expressed Fc gamma R2 in these epithelia, but Fc gamma R1 was not detected. We then demonstrated mRNA for Fc gamma R3 in the columnar endocervical epithelial cells and transformation zone by in situ hybridization, using a CD16-RNA probe. Fc gamma R3 and Fc gamma R2 gene transcripts were also found in fetal cervical tissue by applying the polymerase chain reaction to amplify portions of the Fc gamma R3 and Fc gamma R2 coding sequences in cDNA prepared from fetal RNA. HLA-DR was found in the endocervical cells, transformation zone and in Langerhans cells of all specimens. The presence of Langerhans cells, Fc gamma receptors and HLA class II antigen offers three potential mechanisms for cervico-vaginal HIV transmission: (i) direct HIV infection of Langerhans cells, (ii) binding of HIV antibody complexes

  20. Inhibition of protein phosphorylation by synthetic peptides from the Fc region of human IgG during the mixed lymphocyte response

    SciTech Connect

    McClurg, M.R.; Hahn, G.S.; Plummer, J.M.

    1986-03-01

    Certain synthetic peptides derived from the Fc region of human IgG suppressed protein, RNA, and DNA synthesis during mixed lymphocyte reactions. Responder mononuclear cells were incubated with medium or agents that alter phosphorylation of cellular proteins before immunomodulatory Fc peptides and stimulator cells were added. Incubating cells with trifluoperazine which inhibits calcium binding to calmodulin and inhibits protein kinase C (PKC) increased inhibition of the MLR induced by Fc peptides. Conversely, incubating cells with dubutyryl cyclic AMP (DBcAMP), calmodulin, 1,2-diolein, or phorbol myristate acetate (PMA) abolished inhibition of the MLR induced by Fc peptides. Inhibition of the MLR by Fc ..gamma.. peptides was not affected when DBcAMP or PMA was added after peptide addition. The PKC activity of cell homogenates was decreased by 69% when Fc..gamma.. peptides were present during the MLR. The in vitro phosphorylation of histone Hl by partially purified PKC from lymphocytes was inhibited 74% in the presence of Fc..gamma.. peptides. These results indicate that suppression of the MLR induced by Fc..gamma.. peptides is dependent on inhibition of protein phosphorylation by kinases including protein kinase C. The inhibition of phosphorylation may be related to the ability of Fc..gamma.. peptides to reverse animal models of autoimmune disease.

  1. Differential Use of Human Neutrophil Fcγ Receptors for Inducing Neutrophil Extracellular Trap Formation

    PubMed Central

    Alemán, Omar Rafael; Mora, Nancy; Cortes-Vieyra, Ricarda; Uribe-Querol, Eileen; Rosales, Carlos

    2016-01-01

    Neutrophils (PMN) are the most abundant leukocytes in the blood. PMN migrate from the circulation to sites of infection, where they are responsible for antimicrobial functions. PMN use phagocytosis, degranulation, and formation of neutrophil extracellular traps (NETs) to kill microbes. NETs are fibers composed of chromatin and neutrophil-granule proteins. Several pathogens, including bacteria, fungi, and parasites, and also some pharmacological stimuli such as phorbol 12-myristate 13-acetate (PMA) are efficient inducers of NETs. Antigen-antibody complexes are also capable of inducing NET formation. However the particular Fcγ receptor involved in triggering this function is a matter of controversy. In order to provide some insight into what Fcγ receptor is responsible for NET formation, each of the two human Fcγ receptors was stimulated individually by specific monoclonal antibodies and NET formation was evaluated. FcγRIIa cross-linking did not promote NET formation. Cross-linking other receptors such as integrins also did not promote NET formation. In contrast FcγRIIIb cross-linking induced NET formation similarly to PMA stimulation. NET formation was dependent on NADPH-oxidase, PKC, and ERK activation. These data show that cross-linking FcγRIIIb is responsible for NET formation by the human neutrophil. PMID:27034964

  2. Towards a computational model of leukocyte adhesion cascade: Leukocyte rolling

    NASA Astrophysics Data System (ADS)

    Khismatullin, Damir

    2005-11-01

    Recruitment of leukocytes into sites of acute and chronic inflammation is a vital component of the innate immune response in humans and plays an important role in cardiovascular diseases, such as ischemia-reperfusion injury and atherosclerosis. Leukocytes extravasate into the inflamed tissue through a multi-step process called "leukocyte adhesion cascade", which involves initial contact of a leukocyte with activated endothelium (tethering), leukocyte rolling, firm adhesion, and transendothelial migration. Recently we developed a fully three-dimensional CFD model of receptor-mediated leukocyte adhesion to endothelium in a parallel-plate flow chamber. The model treats the leukocyte as a viscoelastic cell with the nucleus located in the intracellular space and cylindrical microvilli distributed over the cell membrane. Leukocyte-endothelial adhesion is assumed to be mediated by adhesion molecules expressed on the tips of cell microvilli and on endothelium. We show that the model can predict both shape changes and velocities of rolling leukocytes under physiological flow conditions. Results of this study also indicate that viscosity of the cytoplasm is a critical parameter of leukocyte adhesion, affecting the cell's ability to roll on endothelium. This work is supported by NIH Grant HL- 57446 and NCSA Grant BCS040006 and utilized the NCSA IBM p690.

  3. Analyzing antibody-Fc-receptor interactions.

    PubMed

    Nimmerjahn, Falk; Ravetch, Jeffrey V

    2008-01-01

    Cellular receptors for immunoglobulins (Fc-receptors; FcR) are central mediators of antibody-triggered effector functions. Immune complex (IC) binding to FcRs results in a variety of reactions such as the release of inflammatory mediators, antibody dependent cellular cytotoxicity (ADCC) and phagocytosis of ICs. Analyzing antibody-FcR (Ab-FcR) interactions in vitro is essential to determine the effector mechanisms, binding characteristics and affinity parameters that will impact and predict antibody activity in vivo. The methods described in this chapter include the generation of ICs and soluble FcR variants, as well as ELISA and FACS-based assays to study Ab-FcR interactions.

  4. [Oxygen Leukocyte Larceny].

    PubMed

    Pinto da Costa, Miguel; Pimenta Coelho, Henrique

    2016-05-01

    The authors present a case of a 60-year-old male patient, previously diagnosed with B-cell chronic lymphocytic leukemia, who was admitted to the Emergency Room with dyspnea. The initial evaluation revealed severe anemia (Hgb = 5.0 g/dL) with hyperleukocytosis (800.000/µL), nearly all of the cells being mature lymphocytes, a normal chest X-ray and a low arterial oxygen saturation (89%; pulse oximetry). After red blood cell transfusion, Hgb values rose (9.0 g/dL) and there was a complete reversion of the dyspnea. Yet, subsequent arterial blood gas analysis, without the administration of supplemental oxygen, systematically revealed very low oxygen saturation values (~ 46%), which was inconsistent with the patientâs clinical state and his pulse oximetry values (~ 87%), and these values were not corrected by the administration of oxygen via non-rebreather mask. The investigation performed allowed to establish the diagnosis of oxygen leukocyte larceny, a phenomenon which conceals the true oxygen saturation due to peripheral consumption by leukocytes. PMID:27649020

  5. [Oxygen Leukocyte Larceny].

    PubMed

    Pinto da Costa, Miguel; Pimenta Coelho, Henrique

    2016-05-01

    The authors present a case of a 60-year-old male patient, previously diagnosed with B-cell chronic lymphocytic leukemia, who was admitted to the Emergency Room with dyspnea. The initial evaluation revealed severe anemia (Hgb = 5.0 g/dL) with hyperleukocytosis (800.000/µL), nearly all of the cells being mature lymphocytes, a normal chest X-ray and a low arterial oxygen saturation (89%; pulse oximetry). After red blood cell transfusion, Hgb values rose (9.0 g/dL) and there was a complete reversion of the dyspnea. Yet, subsequent arterial blood gas analysis, without the administration of supplemental oxygen, systematically revealed very low oxygen saturation values (~ 46%), which was inconsistent with the patientâs clinical state and his pulse oximetry values (~ 87%), and these values were not corrected by the administration of oxygen via non-rebreather mask. The investigation performed allowed to establish the diagnosis of oxygen leukocyte larceny, a phenomenon which conceals the true oxygen saturation due to peripheral consumption by leukocytes.

  6. Fc Engineering of Human IgG1 for Altered Binding to the Neonatal Fc Receptor Affects Fc Effector Functions.

    PubMed

    Grevys, Algirdas; Bern, Malin; Foss, Stian; Bratlie, Diane Bryant; Moen, Anders; Gunnarsen, Kristin Støen; Aase, Audun; Michaelsen, Terje Einar; Sandlie, Inger; Andersen, Jan Terje

    2015-06-01

    Engineering of the constant Fc part of monoclonal human IgG1 (hIgG1) Abs is an approach to improve effector functions and clinical efficacy of next-generation IgG1-based therapeutics. A main focus in such development is tailoring of in vivo half-life and transport properties by engineering the pH-dependent interaction between IgG and the neonatal Fc receptor (FcRn), as FcRn is the main homeostatic regulator of hIgG1 half-life. However, whether such engineering affects binding to other Fc-binding molecules, such as the classical FcγRs and complement factor C1q, has not been studied in detail. These effector molecules bind to IgG1 in the lower hinge-CH2 region, structurally distant from the binding site for FcRn at the CH2-CH3 elbow region. However, alterations of the structural composition of the Fc may have long-distance effects. Indeed, in this study we show that Fc engineering of hIgG1 for altered binding to FcRn also influences binding to both the classical FcγRs and complement factor C1q, which ultimately results in alterations of cellular mechanisms such as Ab-dependent cell-mediated cytotoxicity, Ab-dependent cellular phagocytosis, and Ab-dependent complement-mediated cell lysis. Thus, engineering of the FcRn-IgG1 interaction may greatly influence effector functions, which has implications for the therapeutic efficacy and use of Fc-engineered hIgG1 variants.

  7. Fc Engineering of Human IgG1 for Altered Binding to the Neonatal Fc Receptor Affects Fc Effector Functions

    PubMed Central

    Grevys, Algirdas; Bern, Malin; Foss, Stian; Bratlie, Diane Bryant; Moen, Anders; Gunnarsen, Kristin Støen; Aase, Audun; Michaelsen, Terje Einar; Sandlie, Inger

    2015-01-01

    Engineering of the constant Fc part of monoclonal human IgG1 (hIgG1) Abs is an approach to improve effector functions and clinical efficacy of next-generation IgG1-based therapeutics. A main focus in such development is tailoring of in vivo half-life and transport properties by engineering the pH-dependent interaction between IgG and the neonatal Fc receptor (FcRn), as FcRn is the main homeostatic regulator of hIgG1 half-life. However, whether such engineering affects binding to other Fc-binding molecules, such as the classical FcγRs and complement factor C1q, has not been studied in detail. These effector molecules bind to IgG1 in the lower hinge–CH2 region, structurally distant from the binding site for FcRn at the CH2–CH3 elbow region. However, alterations of the structural composition of the Fc may have long-distance effects. Indeed, in this study we show that Fc engineering of hIgG1 for altered binding to FcRn also influences binding to both the classical FcγRs and complement factor C1q, which ultimately results in alterations of cellular mechanisms such as Ab-dependent cell-mediated cytotoxicity, Ab-dependent cellular phagocytosis, and Ab-dependent complement-mediated cell lysis. Thus, engineering of the FcRn–IgG1 interaction may greatly influence effector functions, which has implications for the therapeutic efficacy and use of Fc-engineered hIgG1 variants. PMID:25904551

  8. Cryopreservation of Human Mucosal Leukocytes

    PubMed Central

    Shu, Zhiquan; Levy, Claire N.; Ferre, April L.; Hartig, Heather; Fang, Cifeng; Lentz, Gretchen; Fialkow, Michael; Kirby, Anna C.; Adams Waldorf, Kristina M.; Veazey, Ronald S.; Germann, Anja; von Briesen, Hagen; McElrath, M. Juliana; Dezzutti, Charlene S.; Sinclair, Elizabeth; Baker, Chris A. R.; Shacklett, Barbara L.; Gao, Dayong; Hladik, Florian

    2016-01-01

    Background Understanding how leukocytes in the cervicovaginal and colorectal mucosae respond to pathogens, and how medical interventions affect these responses, is important for developing better tools to prevent HIV and other sexually transmitted infections. An effective cryopreservation protocol for these cells following their isolation will make studying them more feasible. Methods and Findings To find an optimal cryopreservation protocol for mucosal mononuclear leukocytes, we compared cryopreservation media and procedures using human vaginal leukocytes and confirmed our results with endocervical and colorectal leukocytes. Specifically, we measured the recovery of viable vaginal T cells and macrophages after cryopreservation with different cryopreservation media and handling procedures. We found several cryopreservation media that led to recoveries above 75%. Limiting the number and volume of washes increased the fraction of cells recovered by 10–15%, possibly due to the small cell numbers in mucosal samples. We confirmed that our cryopreservation protocol also works well for both endocervical and colorectal leukocytes. Cryopreserved leukocytes had slightly increased cytokine responses to antigenic stimulation relative to the same cells tested fresh. Additionally, we tested whether it is better to cryopreserve endocervical cells on the cytobrush or in suspension. Conclusions Leukocytes from cervicovaginal and colorectal tissues can be cryopreserved with good recovery of functional, viable cells using several different cryopreservation media. The number and volume of washes has an experimentally meaningful effect on the percentage of cells recovered. We provide a detailed, step-by-step protocol with best practices for cryopreservation of mucosal leukocytes. PMID:27232996

  9. Effect of protein aggregates on characterization of FcRn binding of Fc-fusion therapeutics.

    PubMed

    Bajardi-Taccioli, Adriana; Blum, Andrew; Xu, Chongfeng; Sosic, Zoran; Bergelson, Svetlana; Feschenko, Marina

    2015-10-01

    Recycling of antibodies and Fc containing therapeutic proteins by the neonatal Fc receptor (FcRn) is known to prolong their persistence in the bloodstream. Fusion of Fc fragment of IgG1 to other proteins is one of the strategies to improve their pharmacokinetic properties. Accurate measurement of Fc-FcRn binding provides information about the strength of this interaction, which in most cases correlates with serum half-life of the protein. It can also offer insight into functional integrity of Fc region. We investigated FcRn binding activity of a large set of Fc-fusion samples after thermal stress by the method based on AlphaScreen technology. An unexpected significant increase in FcR binding was found to correlate with formation of aggregates in these samples. Monomer purified from a thermally-stressed sample had normal FcRn binding, confirming that its Fc portion was intact. Experiments with aggregates spiked into a sample with low initial aggregation level, demonstrated strong correlation between the level of aggregates and FcRn binding. This correlation varied significantly in different methods. By introducing modifications to the assay format we were able to minimize the effects of aggregated species on FcRn binding, which should prevent masking functional changes of Fc-fusion protein. Biolayer interferometry (BLI) was used as an alternative method to measure FcRn binding. Both optimized AlphaScreen- and BLI-based assays were sensitive to structural changes in Fc portion of the molecule, such as oxidation of methionines 252 and 428, and therefore suitable for characterization of FcRn binding.

  10. Targeting the neonatal fc receptor for antigen delivery using engineered fc fragments.

    PubMed

    Mi, Wentao; Wanjie, Sylvia; Lo, Su-Tang; Gan, Zhuo; Pickl-Herk, Beatrix; Ober, Raimund J; Ward, E Sally

    2008-12-01

    The development of approaches for Ag delivery to the appropriate subcellular compartments of APCs and the optimization of Ag persistence are both of central relevance for the induction of protective immunity or tolerance. The expression of the neonatal Fc receptor, FcRn, in APCs and its localization to the endosomal system suggest that it might serve as a target for Ag delivery using engineered Fc fragment-epitope fusions. The impact of FcRn binding characteristics of an Fc fragment on in vivo persistence allows this property to also be modulated. We have therefore generated recombinant Fc (mouse IgG1-derived) fusions containing the N-terminal epitope of myelin basic protein that is associated with experimental autoimmune encephalomyelitis in H-2(u) mice. The Fc fragments have distinct binding properties for FcRn that result in differences in intracellular trafficking and in vivo half-lives, allowing the impact of these characteristics on CD4(+) T cell responses to be evaluated. To dissect the relative roles of FcRn and the "classical" FcgammaRs in Ag delivery, analogous aglycosylated Fc-MBP fusions have been generated. We show that engineered Fc fragments with increased affinities for FcRn at pH 6.0-7.4 are more effective in delivering Ag to FcRn-expressing APCs in vitro relative to their lower affinity counterparts. However, higher affinity of the FcRn-Fc interaction at near neutral pH results in decreased in vivo persistence. The trade-off between improved FcRn targeting efficiency and lower half-life becomes apparent during analyses of T cell proliferative responses in mice, particularly when Fc-MBP fusions with both FcRn and FcgammaR binding activity are used.

  11. Antibody Fc: Linking Adaptive and Innate Immunity

    PubMed Central

    Reichert, Janice M.

    2014-01-01

    Antibody Fc: Linking Adaptive and Innate Immunity, edited by Margaret E. Ackerman and Falk Nimmerjahn and published by Academic Press, provides a highly detailed examination of the involvement of the antibody Fc in mechanisms critical to both innate and adaptive immune responses. Despite a recent increase in format diversity, most marketed antibodies are full-length IgG molecules and the majority of the commercial clinical pipeline of antibody therapeutics is composed of Fc-containing IgG molecules, which underscores the importance of understanding how the Fc domain affects biological responses. The book is divided into six sections that include a total of 20 chapters. In order of their appearance, the sections provide extensive coverage of effector mechanisms, effector cells, Fc receptors, variability of the Fc domain, genetic associations, and evolving areas.

  12. 21 CFR 866.5530 - Immunoglobulin G (Fc fragment specific) immunological test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Immunoglobulin G (Fc fragment specific) immunological test system. 866.5530 Section 866.5530 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... abnormalities, e.g., gamma heavy chain disease. (b) Classification. Class I (general controls). The device...

  13. 21 CFR 866.5530 - Immunoglobulin G (Fc fragment specific) immunological test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Immunoglobulin G (Fc fragment specific) immunological test system. 866.5530 Section 866.5530 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... abnormalities, e.g., gamma heavy chain disease. (b) Classification. Class I (general controls). The device...

  14. 21 CFR 866.5530 - Immunoglobulin G (Fc fragment specific) immunological test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Immunoglobulin G (Fc fragment specific) immunological test system. 866.5530 Section 866.5530 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... abnormalities, e.g., gamma heavy chain disease. (b) Classification. Class I (general controls). The device...

  15. 21 CFR 866.5530 - Immunoglobulin G (Fc fragment specific) immunological test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Immunoglobulin G (Fc fragment specific) immunological test system. 866.5530 Section 866.5530 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... abnormalities, e.g., gamma heavy chain disease. (b) Classification. Class I (general controls). The device...

  16. HAL/S-FC compiler system specifications

    NASA Technical Reports Server (NTRS)

    1976-01-01

    This document specifies the informational interfaces within the HAL/S-FC compiler, and between the compiler and the external environment. This Compiler System Specification is for the HAL/S-FC compiler and its associated run time facilities which implement the full HAL/S language. The HAL/S-FC compiler is designed to operate stand-alone on any compatible IBM 360/370 computer and within the Software Development Laboratory (SDL) at NASA/JSC, Houston, Texas.

  17. Khatyrka, a new <fc>CV>3 find from the Koryak Mountains, Eastern Russia

    NASA Astrophysics Data System (ADS)

    MacPherson, Glenn J.; Andronicos, Christopher L.; Bindi, Luca; Distler, Vadim V.; Eddy, Michael P.; Eiler, John M.; Guan, Yunbin; Hollister, Lincoln S.; Kostin, Alexander; Kryachko, Valery; Steinhardt, William M.; Yudovskaya, Marina; Steinhardt, Paul J.

    2013-08-01

    A new meteorite find, named Khatyrka, was recovered from eastern Siberia as a result of a search for naturally occurring quasicrystals. The meteorite occurs as clastic grains within postglacial clay-rich layers along the banks of a small stream in the Koryak Mountains, Chukotka Autonomous Okrug of far eastern Russia. Some of the grains are clearly chondritic and contain Type <fc>IA> porphyritic olivine chondrules enclosed in matrices that have the characteristic platy olivine texture, matrix olivine composition, and mineralogy (olivine, pentlandite, nickel-rich iron-nickel metal, nepheline, and calcic pyroxene [diopside-hedenbergite solid solution]) of oxidized-subgroup <fc>CV>3 chondrites. A few grains are fine-grained spinel-rich calcium-aluminum-rich inclusions with mineral oxygen isotopic compositions again typical of such objects in <fc>CV>3 chondrites. The chondritic and <fc>CAI> grains contain small fragments of metallic copper-aluminum-iron alloys that include the quasicrystalline phase icosahedrite. One grain is an achondritic intergrowth of Cu-Al metal alloys and forsteritic olivine ± diopsidic pyroxene, both of which have meteoritic (<fc>CV>3-like) oxygen isotopic compositions. Finally, some grains consist almost entirely of metallic alloys of aluminum + copper ± iron. The Cu-Al-Fe metal alloys and the alloy-bearing achondrite clast are interpreted to be an accretionary component of what otherwise is a fairly normal <fc>CV>3 (oxidized) chondrite. This association of <fc>CV>3 chondritic grains with metallic copper-aluminum alloys makes Khatyrka a unique meteorite, perhaps best described as a complex <fc>CV>3 (ox) breccia.

  18. Novel asymmetrically engineered antibody Fc variant with superior FcγR binding affinity and specificity compared with afucosylated Fc variant

    PubMed Central

    Mimoto, Futa; Igawa, Tomoyuki; Kuramochi, Taichi; Katada, Hitoshi; Kadono, Shojiro; Kamikawa, Takayuki; Shida-Kawazoe, Meiri; Hattori, Kunihiro

    2013-01-01

    Fc engineering is a promising approach to enhance the antitumor efficacy of monoclonal antibodies (mAbs) through antibody-dependent cell-mediated cytotoxicity (ADCC). Glyco- and protein-Fc engineering have been employed to enhance FcγR binding and ADCC activity of mAbs; the drawbacks of previous approaches lie in their binding affinity to both FcγRIIIa allotypes, the ratio of activating FcγR binding to inhibitory FcγR binding (A/I ratio) or the melting temperature (TM) of the CH2 domain. To date, no engineered Fc variant has been reported that satisfies all these points. Herein, we present a novel Fc engineering approach that introduces different substitutions in each Fc domain asymmetrically, conferring optimal binding affinity to FcγR and specificity to the activating FcγR without impairing the stability. We successfully designed an asymmetric Fc variant with the highest binding affinity for both FcγRIIIa allotypes and the highest A/I ratio compared with previously reported symmetrically engineered Fc variants, and superior or at least comparable in vitro ADCC activity compared with afucosylated Fc variants. In addition, the asymmetric Fc engineering approach offered higher stability by minimizing the use of substitutions that reduce the TM of the CH2 domain compared with the symmetric approach. These results demonstrate that the asymmetric Fc engineering platform provides best-in-class effector function for therapeutic antibodies against tumor antigens. PMID:23406628

  19. Engineering of Immunoglobulin Fc Heterodimers Using Yeast Surface-Displayed Combinatorial Fc Library Screening

    PubMed Central

    Choi, Hye-Ji; Kim, Ye-Jin; Choi, Dong-Ki; Kim, Yong-Sung

    2015-01-01

    Immunoglobulin Fc heterodimers, which are useful scaffolds for the generation of bispecific antibodies, have been mostly generated through structure-based rational design methods that introduce asymmetric mutations into the CH3 homodimeric interface to favor heterodimeric Fc formation. Here, we report an approach to generate heterodimeric Fc variants through directed evolution combined with yeast surface display. We developed a combinatorial heterodimeric Fc library display system by mating two haploid yeast cell lines, one haploid cell line displayed an Fc chain library (displayed FcCH3A) with mutations in one CH3 domain (CH3A) on the yeast cell surface, and the other cell line secreted an Fc chain library (secreted FcCH3B) with mutations in the other CH3 domain (CH3B). In the mated cells, secreted FcCH3B is displayed on the cell surface through heterodimerization with the displayed FcCH3A, the detection of which enabled us to screen the library for heterodimeric Fc variants. We constructed combinatorial heterodimeric Fc libraries with simultaneous mutations in the homodimer-favoring electrostatic interaction pairs K370-E357/S364 or D399-K392/K409 at the CH3 domain interface. High-throughput screening of the libraries using flow cytometry yielded heterodimeric Fc variants with heterodimer-favoring CH3 domain interface mutation pairs, some of them showed high heterodimerization yields (~80–90%) with previously unidentified CH3 domain interface mutation pairs, such as hydrogen bonds and cation-π interactions. Our study provides a new approach for engineering Fc heterodimers that could be used to engineer other heterodimeric protein-protein interactions through directed evolution combined with yeast surface display. PMID:26675656

  20. Engineering of Immunoglobulin Fc Heterodimers Using Yeast Surface-Displayed Combinatorial Fc Library Screening.

    PubMed

    Choi, Hye-Ji; Kim, Ye-Jin; Choi, Dong-Ki; Kim, Yong-Sung

    2015-01-01

    Immunoglobulin Fc heterodimers, which are useful scaffolds for the generation of bispecific antibodies, have been mostly generated through structure-based rational design methods that introduce asymmetric mutations into the CH3 homodimeric interface to favor heterodimeric Fc formation. Here, we report an approach to generate heterodimeric Fc variants through directed evolution combined with yeast surface display. We developed a combinatorial heterodimeric Fc library display system by mating two haploid yeast cell lines, one haploid cell line displayed an Fc chain library (displayed FcCH3A) with mutations in one CH3 domain (CH3A) on the yeast cell surface, and the other cell line secreted an Fc chain library (secreted FcCH3B) with mutations in the other CH3 domain (CH3B). In the mated cells, secreted FcCH3B is displayed on the cell surface through heterodimerization with the displayed FcCH3A, the detection of which enabled us to screen the library for heterodimeric Fc variants. We constructed combinatorial heterodimeric Fc libraries with simultaneous mutations in the homodimer-favoring electrostatic interaction pairs K370-E357/S364 or D399-K392/K409 at the CH3 domain interface. High-throughput screening of the libraries using flow cytometry yielded heterodimeric Fc variants with heterodimer-favoring CH3 domain interface mutation pairs, some of them showed high heterodimerization yields (~80-90%) with previously unidentified CH3 domain interface mutation pairs, such as hydrogen bonds and cation-π interactions. Our study provides a new approach for engineering Fc heterodimers that could be used to engineer other heterodimeric protein-protein interactions through directed evolution combined with yeast surface display. PMID:26675656

  1. Phenotyping of Leukocytes and Leukocyte-Derived Extracellular Vesicles.

    PubMed

    Pugholm, Lotte Hatting; Bæk, Rikke; Søndergaard, Evo Kristina Lindersson; Revenfeld, Anne Louise Schacht; Jørgensen, Malene Møller; Varming, Kim

    2016-01-01

    Extracellular vesicles (EVs) have a demonstrated involvement in modulating the immune system. It has been proposed that EVs could be used as biomarkers for detection of inflammatory and immunological disorders. Consequently, it is of great interest to investigate EVs in more detail with focus on immunological markers. In this study, five major leukocyte subpopulations and the corresponding leukocyte-derived EVs were phenotyped with focus on selected immunological lineage-specific markers and selected vesicle-related markers. The leukocyte-derived EVs displayed phenotypic differences in the 34 markers investigated. The majority of the lineage-specific markers used for identification of the parent cell types could not be detected on EVs released from monocultures of the associated cell types. In contrast, the vesicular presentation of CD9, CD63, and CD81 correlated to the cell surface expression of these markers, however, with few exceptions. Furthermore, the cellular expression of CD9, CD63, and CD81 varied between leukocytes present in whole blood and cultured leukocytes. In summary, these data demonstrate that the cellular and vesicular presentation of selected lineage-specific and vesicle-related markers may differ, supporting the accumulating observations that sorting of molecular cargo into EVs is tightly controlled.

  2. The neonatal Fc receptor, FcRn, as a target for drug delivery and therapy

    PubMed Central

    Sockolosky, Jonathan T.; Szoka, Francis C.

    2015-01-01

    Immunoglobulin G (IgG)-based drugs are arguably the most successful class of protein therapeutics due in part to their remarkably long blood circulation. This arises from IgG interaction with the neonatal Fc receptor, FcRn. FcRn is the central regulator of IgG and albumin homeostasis throughout life and is increasingly being recognized as an important player in autoimmune disease, mucosal immunity, and tumor immune surveillance. Various engineering approaches that hijack or disrupt the FcRn-mediated transport pathway have been devised to develop long-lasting and non-invasive protein therapeutics, protein subunit vaccines, and therapeutics for treatment of autoimmune and infectious disease. In this review, we highlight the diverse biological functions of FcRn, emerging therapeutic opportunities, as well as the associated challenges of targeting FcRn for drug delivery and disease therapy. PMID:25703189

  3. Generation of memory CD4+, CD8+, CD45RO+ and CD16- lymphocytes activated with IL-2, INF-gamma, and TNF-alpha with specific cytotoxicity against autologous cervical cancer cells in a mixed leukocyte-tumour cell culture.

    PubMed

    Rangel, R; Rocha, L; Ramirez, J L; Ibarra, M J; Solorza, G; Monroy, A; Ramirez, M A; Herrera, A; Weiss-Steider, B

    1995-01-01

    Cytotoxic T lymphocytes (CTL) specific against autologous human cervical cancer cells were generated in vitro from peripheral blood leukocytes (PBL) from four patients with non-keratinized epidermoid carcinoma. For this purpose, these patients' PBL were co-cultured for 28 days either with IL-2 or a mixture of IL-2, IFN-gamma and TNF-alpha in the presence of autologous tumour cells (ATC). Our results showed that these CTL were highly cytotoxic for ATC, weakly cytotoxic for heterologous cervical cancer tumour cells, and not cytotoxic for carcinoma cell lines, normal cervix cells nor autologous PBL. Proliferation and cytotoxicity against ATC were greater when the PBL were activated with the three cytokines. These CTL had a CD4:CD8 ratio of 1:1, were CD16- and CD45RO+ and their killing activity was inhibited by antibodies against CD3, CD8 and MHC-class I but not by antibodies against CD4, CD16 or HLA-class II. The possibility of generating specific CTL in long term cultures for cervical cancer therapy is also discussed.

  4. Importance of the Side Chain at Position 296 of Antibody Fc in Interactions with FcγRIIIa and Other Fcγ Receptors.

    PubMed

    Isoda, Yuya; Yagi, Hirokazu; Satoh, Tadashi; Shibata-Koyama, Mami; Masuda, Kazuhiro; Satoh, Mitsuo; Kato, Koichi; Iida, Shigeru

    2015-01-01

    Antibody-dependent cellular cytotoxicity (ADCC) is an important effector function determining the clinical efficacy of therapeutic antibodies. Core fucose removal from N-glycans on the Fc portion of immunoglobulin G (IgG) improves the binding affinity for Fcγ receptor IIIa (FcγRIIIa) and dramatically enhances ADCC. Our previous structural analyses revealed that Tyr-296 of IgG1-Fc plays a critical role in the interaction with FcγRIIIa, particularly in the enhanced FcγRIIIa binding of nonfucosylated IgG1. However, the importance of the Tyr-296 residue in the antibody in the interaction with various Fcγ receptors has not yet been elucidated. To further clarify the biological importance of this residue, we established comprehensive Tyr-296 mutants as fucosylated and nonfucosylated anti-CD20 IgG1s rituximab variants and examined their binding to recombinant soluble human Fcγ receptors: shFcγRI, shFcγRIIa, shFcγRIIIa, and shFcγRIIIb. Some of the mutations affected the binding of antibody to not only shFcγRIIIa but also shFcγRIIa and shFcγRIIIb, suggesting that the Tyr-296 residue in the antibody was also involved in interactions with FcγRIIa and FcγRIIIb. For FcγRIIIa binding, almost all Tyr-296 variants showed lower binding affinities than the wild-type antibody, irrespective of their core fucosylation, particularly in Y296K and Y296P. Notably, only the Y296W mutant showed improved binding to FcγRIIIa. The 3.00 Å-resolution crystal structure of the nonfucosylated Y296W mutant in complex with shFcγRIIIa harboring two N-glycans revealed that the Tyr-to-Trp substitution increased the number of potential contact atoms in the complex, thus improving the binding of the antibody to shFcγRIIIa. The nonfucosylated Y296W mutant retained high ADCC activity, relative to the nonfucosylated wild-type IgG1, and showed greater binding affinity for FcγRIIa. Our data may improve our understanding of the biological importance of human IgG1-Fc Tyr-296 in interactions

  5. Importance of the Side Chain at Position 296 of Antibody Fc in Interactions with FcγRIIIa and Other Fcγ Receptors

    PubMed Central

    Isoda, Yuya; Yagi, Hirokazu; Satoh, Tadashi; Shibata-Koyama, Mami; Masuda, Kazuhiro; Satoh, Mitsuo; Kato, Koichi; Iida, Shigeru

    2015-01-01

    Antibody-dependent cellular cytotoxicity (ADCC) is an important effector function determining the clinical efficacy of therapeutic antibodies. Core fucose removal from N-glycans on the Fc portion of immunoglobulin G (IgG) improves the binding affinity for Fcγ receptor IIIa (FcγRIIIa) and dramatically enhances ADCC. Our previous structural analyses revealed that Tyr–296 of IgG1-Fc plays a critical role in the interaction with FcγRIIIa, particularly in the enhanced FcγRIIIa binding of nonfucosylated IgG1. However, the importance of the Tyr–296 residue in the antibody in the interaction with various Fcγ receptors has not yet been elucidated. To further clarify the biological importance of this residue, we established comprehensive Tyr–296 mutants as fucosylated and nonfucosylated anti-CD20 IgG1s rituximab variants and examined their binding to recombinant soluble human Fcγ receptors: shFcγRI, shFcγRIIa, shFcγRIIIa, and shFcγRIIIb. Some of the mutations affected the binding of antibody to not only shFcγRIIIa but also shFcγRIIa and shFcγRIIIb, suggesting that the Tyr–296 residue in the antibody was also involved in interactions with FcγRIIa and FcγRIIIb. For FcγRIIIa binding, almost all Tyr–296 variants showed lower binding affinities than the wild-type antibody, irrespective of their core fucosylation, particularly in Y296K and Y296P. Notably, only the Y296W mutant showed improved binding to FcγRIIIa. The 3.00 Å-resolution crystal structure of the nonfucosylated Y296W mutant in complex with shFcγRIIIa harboring two N-glycans revealed that the Tyr-to-Trp substitution increased the number of potential contact atoms in the complex, thus improving the binding of the antibody to shFcγRIIIa. The nonfucosylated Y296W mutant retained high ADCC activity, relative to the nonfucosylated wild-type IgG1, and showed greater binding affinity for FcγRIIa. Our data may improve our understanding of the biological importance of human IgG1-Fc Tyr–296 in

  6. Importance of the Side Chain at Position 296 of Antibody Fc in Interactions with FcγRIIIa and Other Fcγ Receptors.

    PubMed

    Isoda, Yuya; Yagi, Hirokazu; Satoh, Tadashi; Shibata-Koyama, Mami; Masuda, Kazuhiro; Satoh, Mitsuo; Kato, Koichi; Iida, Shigeru

    2015-01-01

    Antibody-dependent cellular cytotoxicity (ADCC) is an important effector function determining the clinical efficacy of therapeutic antibodies. Core fucose removal from N-glycans on the Fc portion of immunoglobulin G (IgG) improves the binding affinity for Fcγ receptor IIIa (FcγRIIIa) and dramatically enhances ADCC. Our previous structural analyses revealed that Tyr-296 of IgG1-Fc plays a critical role in the interaction with FcγRIIIa, particularly in the enhanced FcγRIIIa binding of nonfucosylated IgG1. However, the importance of the Tyr-296 residue in the antibody in the interaction with various Fcγ receptors has not yet been elucidated. To further clarify the biological importance of this residue, we established comprehensive Tyr-296 mutants as fucosylated and nonfucosylated anti-CD20 IgG1s rituximab variants and examined their binding to recombinant soluble human Fcγ receptors: shFcγRI, shFcγRIIa, shFcγRIIIa, and shFcγRIIIb. Some of the mutations affected the binding of antibody to not only shFcγRIIIa but also shFcγRIIa and shFcγRIIIb, suggesting that the Tyr-296 residue in the antibody was also involved in interactions with FcγRIIa and FcγRIIIb. For FcγRIIIa binding, almost all Tyr-296 variants showed lower binding affinities than the wild-type antibody, irrespective of their core fucosylation, particularly in Y296K and Y296P. Notably, only the Y296W mutant showed improved binding to FcγRIIIa. The 3.00 Å-resolution crystal structure of the nonfucosylated Y296W mutant in complex with shFcγRIIIa harboring two N-glycans revealed that the Tyr-to-Trp substitution increased the number of potential contact atoms in the complex, thus improving the binding of the antibody to shFcγRIIIa. The nonfucosylated Y296W mutant retained high ADCC activity, relative to the nonfucosylated wild-type IgG1, and showed greater binding affinity for FcγRIIa. Our data may improve our understanding of the biological importance of human IgG1-Fc Tyr-296 in interactions

  7. Detection of CFTR protein in human leukocytes by flow cytometry.

    PubMed

    Johansson, Jan; Vezzalini, Marzia; Verzè, Genny; Caldrer, Sara; Bolognin, Silvia; Buffelli, Mario; Bellisola, Giuseppe; Tridello, Gloria; Assael, Baroukh Maurice; Melotti, Paola; Sorio, Claudio

    2014-07-01

    Leukocytes have previously been shown to express detectable levels of the protein cystic fibrosis transmembrane conductance regulator (CFTR). This study aims to evaluate the application of flow cytometric (FC) analysis to detect CFTR expression, and changes thereof, in these cells. Aliquots (200 μL) of peripheral whole blood from 12 healthy control volunteers (CTRLs), 12 carriers of a CFTR mutation (CFC), and 40 patients with cystic fibrosis (CF) carrying various combinations of CFTR mutations were incubated with specific fluorescent probes recognizing CFTR protein expressed on the plasma membrane of leukocytes. FC was applied to analyze CFTR expression in monocytes, lymphocytes, and polymorphonuclear (PMN) cells. CFTR protein was detected in monocytes and lymphocytes, whereas inconclusive results were obtained from the analysis of PMN cells. Mean fluorescence intensity (MFI) ratio value and %CFTR-positive cells above a selected threshold were the two parameters selected to quantify CFTR expression in cells. Lowest variability and the highest reproducibility were obtained when analyzing monocytes. ANOVA results indicated that both parameters were able to discriminate monocytes of healthy controls and CF individuals according to CFTR mutation classes with high accuracy. Significantly increased MFI ratio values were recorded in CFTR-defective cells that were also able to improve CFTR function after ex vivo treatment with PTC124 (Ataluren), an investigative drug designed to permit the ribosome to read through nonsense CFTR mutations. The method described is minimally invasive and may be used in the monitoring of responses to drugs whose efficacy can depend on increased CFTR protein expression levels. © 2014 International Society for Advancement of Cytometry.

  8. Downmodulation of Vaccine-Induced Immunity and Protection against the Intracellular Bacterium Francisella tularensis by the Inhibitory Receptor FcγRIIB

    PubMed Central

    Franz, Brian J.; Li, Ying; Bitsaktsis, Constantine; Iglesias, Bibiana V.; Pham, Giang; Sunagar, Raju; Kumar, Sudeep; Gosselin, Edmund J.

    2015-01-01

    Fc gamma receptor IIB (FcγRIIB) is the only Fc gamma receptor (FcγR) which negatively regulates the immune response, when engaged by antigen- (Ag-) antibody (Ab) complexes. Thus, the generation of Ag-specific IgG in response to infection or immunization has the potential to downmodulate immune protection against infection. Therefore, we sought to determine the impact of FcγRIIB on immune protection against Francisella tularensis (Ft), a Category A biothreat agent. We utilized inactivated Ft (iFt) as an immunogen. Naïve and iFt-immunized FcγRIIB knockout (KO) or wildtype (WT) mice were challenged with Ft-live vaccine strain (LVS). While no significant difference in survival between naïve FcγRIIB KO versus WT mice was observed, iFt-immunized FcγRIIB KO mice were significantly better protected than iFt-immunized WT mice. Ft-specific IgA in serum and bronchial alveolar lavage, as well as IFN-γ, IL-10, and TNF-α production by splenocytes harvested from iFt-immunized FcγRIIB KO, were also significantly elevated. In addition, iFt-immunized FcγRIIB KO mice exhibited a reduction in proinflammatory cytokine levels in vivo at 5 days after challenge, which correlates with increased survival following Ft-LVS challenge in published studies. Thus, these studies demonstrate for the first time the ability of FcγRIIB to regulate vaccine-induced IgA production and downmodulate immunity and protection. The immune mechanisms behind the above observations and their potential impact on vaccine development are discussed. PMID:25961064

  9. Novel asymmetrically engineered antibody Fc variant with superior FcγR binding affinity and specificity compared with afucosylated Fc variant.

    PubMed

    Mimoto, Futa; Igawa, Tomoyuki; Kuramochi, Taichi; Katada, Hitoshi; Kadono, Shojiro; Kamikawa, Takayuki; Shida-Kawazoe, Meiri; Hattori, Kunihiro

    2013-01-01

    Fc engineering is a promising approach to enhance the antitumor efficacy of monoclonal antibodies (mAbs) through antibody-dependent cell-mediated cytotoxicity (ADCC). Glyco- and protein-Fc engineering have been employed to enhance FcγR binding and ADCC activity of mAbs; the drawbacks of previous approaches lie in their binding affinity to both FcγRIIIa allotypes, the ratio of activating FcγR binding to inhibitory FcγR binding (A/I ratio) or the melting temperature (T(M)) of the C(H)2 domain. To date, no engineered Fc variant has been reported that satisfies all these points. Herein, we present a novel Fc engineering approach that introduces different substitutions in each Fc domain asymmetrically, conferring optimal binding affinity to FcγR and specificity to the activating FcγR without impairing the stability. We successfully designed an asymmetric Fc variant with the highest binding affinity for both FcγRIIIa allotypes and the highest A/I ratio compared with previously reported symmetrically engineered Fc variants, and superior or at least comparable in vitro ADCC activity compared with afucosylated Fc variants. In addition, the asymmetric Fc engineering approach offered higher stability by minimizing the use of substitutions that reduce the T(M) of the C(H)2 domain compared with the symmetric approach. These results demonstrate that the asymmetric Fc engineering platform provides best-in-class effector function for therapeutic antibodies against tumor antigens.

  10. Integrated profiling of Furanocoumarins (FC) in Grapefruit hybrids toward selection of low FC varieties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Furanocoumarins (FC) are a class of organic chemical components in grapefruits and other diet plants. Some of them in grapefruit juice can induce potentially adverse interactions with human drugs and in that patients may be advised to avoid the fruit and juice. To develop low FC grapefruit cultivars...

  11. Fc-fusion proteins and FcRn: structural insights for longer-lasting and more effective therapeutics

    PubMed Central

    Rath, Timo; Baker, Kristi; Dumont, Jennifer A.; Peters, Robert T.; Jiang, Haiyan; Qiao, Shuo-Wang; Lencer, Wayne I.; Pierce, Glenn F.; Blumberg, Richard S.

    2016-01-01

    Nearly 350 IgG-based therapeutics are approved for clinical use or are under development for many diseases lacking adequate treatment options. These include molecularly engineered biologicals comprising the IgG Fc-domain fused to various effector molecules (so-called Fc-fusion proteins) that confer the advantages of IgG, including binding to the neonatal Fc receptor (FcRn) to facilitate in vivo stability, and the therapeutic benefit of the specific effector functions. Advances in IgG structure-function relationships and an understanding of FcRn biology have provided therapeutic opportunities for previously unapproachable diseases. This article discusses approved Fc-fusion therapeutics, novel Fc-fusion proteins and FcRn-dependent delivery approaches in development, and how engineering of the FcRn–Fc interaction can generate longer-lasting and more effective therapeutics. PMID:24156398

  12. The long elusive IgM Fc receptor, FcμR.

    PubMed

    Kubagawa, Hiromi; Oka, Satoshi; Kubagawa, Yoshiki; Torii, Ikuko; Takayama, Eiji; Kang, Dong-Won; Jones, Dewitt; Nishida, Naonori; Miyawaki, Toshio; Bertoli, Luigi F; Sanders, Sheila K; Honjo, Kazuhito

    2014-07-01

    IgM exists as both a monomer on the surface of B cells and a pentamer secreted by plasma cells. Both pre-immune "natural" and antigen-induced "immune" IgM antibodies are important for protective immunity and for immune regulation of autoimmune processes by recognizing pathogens and self-antigens. Effector proteins interacting with the Fc portion of IgM, such as complement and complement receptors, have thus far been proposed but fail to fully account for the IgM-mediated protection and regulation. A major reason for this deficit in our understanding of IgM function seems to be lack of data on a long elusive Fc receptor for IgM (FcμR). We have recently identified a bona fide FcμR in both humans and mice. In this article we briefly review what we have learned so far about FcμR.

  13. Chemoenzymatic Synthesis and Fcγ Receptor Binding of Homogeneous Glycoforms of Antibody Fc Domain. Presence of a Bisecting Sugar Moiety Enhances the Affinity of Fc to FcγIIIa Receptor

    PubMed Central

    Zou, Guozhang; Ochiai, Hirofumi; Huang, Wei; Yang, Qiang; Li, Cishan; Wang, Lai-Xi

    2011-01-01

    Structurally well-defined IgG-Fc glycoforms are highly demanded for understanding the effects of glycosylation on antibody’s effector functions. We report in this paper chemoenzymatic synthesis and Fcγ receptor binding of an array of homogeneous IgG-Fc glycoforms. The chemoenzymatic approach consists of the chemical synthesis of defined N-glycan oxazolines as donor substratess, the expression of the Fc domain in a CHO cell line in the presence of an α-mannosidase inhibitor kifunensine, and an endoglycosidase-catalyzed glycosylation of the deglycosylated Fc domain (GlcNAc-Fc homodimer) with the synthetic glycan oxazolines. The enzyme from Arthrobacter protophormiae (Endo-A) was found to be remarkably efficient to take various modified N-glycan core oxazolines, including the bisecting sugar-containing derivatives, for Fc glycosylation remodeling, resulting in the formation of the corresponding homogeneous Fc glycoforms. Nevertheless, neither Endo-A, nor the Mucor hiemalis endoglycosidase mutants (EndoM-N175A and EndoM-N175Q), was able to transfer full-length complex-type N-glycan to the Fc domain, implicating the limitations of these two enzymes in Fc glycosylation remodeling. SPR binding studies with the synthetic IgG-Fc glycoforms unambiguously proved that the presence of a bisecting GlcNAc moiety could significantly enhance the binding of Fc to FcγRIIIa, the activating Fcγ receptor, independent of Fc core-fucosylation. Interestingly, the Fc glycoforms carrying an unusual bisecting sugar moiety such as a mannose or a LacNAc moiety also demonstrated enhanced affinity to FcγRIIIa. On the orther hand, the presence of a bisecting GlcNAc or core fucosylation had little effect on the affinity of Fc to the inhibitory Fcγ receptor, FcγRIIb. Our experimental data also showed that the α-linked mannose residues in the pentasaccharide Man3GlcNAc2 core was essential to maintain a high-affinity of Fc to both FcγRIIIa and FcγRIIb. The synthetic homogeneous Fc

  14. Chemoenzymatic synthesis and Fcγ receptor binding of homogeneous glycoforms of antibody Fc domain. Presence of a bisecting sugar moiety enhances the affinity of Fc to FcγIIIa receptor.

    PubMed

    Zou, Guozhang; Ochiai, Hirofumi; Huang, Wei; Yang, Qiang; Li, Cishan; Wang, Lai-Xi

    2011-11-23

    Structurally well-defined IgG-Fc glycoforms are highly demanded for understanding the effects of glycosylation on an antibody's effector functions. We report in this paper chemoenzymatic synthesis and Fcγ receptor binding of an array of homogeneous IgG-Fc glycoforms. The chemoenzymatic approach consists of the chemical synthesis of defined N-glycan oxazolines as donor substrates, the expression of the Fc domain in a CHO cell line in the presence of an α-mannosidase inhibitor kifunensine, and an endoglycosidase-catalyzed glycosylation of the deglycosylated Fc domain (GlcNAc-Fc homodimer) with the synthetic glycan oxazolines. The enzyme from Arthrobacter protophormiae (Endo-A) was found to be remarkably efficient to take various modified N-glycan core oxazolines, including the bisecting sugar-containing derivatives, for Fc glycosylation remodeling, resulting in the formation of the corresponding homogeneous Fc glycoforms. Nevertheless, neither Endo-A nor the Mucor hiemalis endoglycosidase mutants (EndoM-N175A and EndoM-N175Q) were able to transfer full-length complex-type N-glycan to the Fc domain, implicating the limitations of these two enzymes in Fc glycosylation remodeling. Surface plasmon resonance (SPR) binding studies with the synthetic IgG-Fc glycoforms unambiguously proved that the presence of a bisecting GlcNAc moiety could significantly enhance the binding of Fc to FcγRIIIa, the activating Fcγ receptor, independent of Fc core-fucosylation. Interestingly, the Fc glycoforms carrying an unusual bisecting sugar moiety such as a mannose or a LacNAc moiety also demonstrated enhanced affinity to FcγRIIIa. On the orther hand, the presence of a bisecting GlcNAc or core-fucosylation had little effect on the affinity of Fc to the inhibitory Fcγ receptor, FcγRIIb. Our experimental data also showed that the α-linked mannose residues in the pentasaccharide Man3GlcNAc2 core was essential to maintain a high affinity of Fc to both FcγRIIIa and FcγRIIb. The

  15. Broadly Neutralizing Hemagglutinin Stalk-Specific Antibodies Induce Potent Phagocytosis of Immune Complexes by Neutrophils in an Fc-Dependent Manner

    PubMed Central

    Mullarkey, Caitlin E.; Bailey, Mark J.; Golubeva, Diana A.; Tan, Gene S.; Nachbagauer, Raffael; He, Wenqian; Novakowski, Kyle E.; Bowdish, Dawn M.; Miller, Matthew S.

    2016-01-01

    ABSTRACT Broadly neutralizing antibodies that recognize the conserved hemagglutinin (HA) stalk have emerged as exciting new biotherapeutic tools to combat seasonal and pandemic influenza viruses. Our general understanding of the mechanisms by which stalk-specific antibodies achieve protection is rapidly evolving. It has recently been demonstrated that broadly neutralizing HA stalk-specific IgG antibodies require Fc-Fcγ receptor (FcγR) interactions for optimal protection in vivo. Here we examine the neutrophil effector functions induced by stalk-specific antibodies. As the most abundant subset of blood leukocytes, neutrophils represent a critical innate effector cell population and serve an instrumental role in orchestrating downstream adaptive responses to influenza virus infection. Yet, the interplay of HA stalk-specific IgG, Fc-FcγR engagement, and neutrophils has remained largely uncharacterized. Using an in vitro assay to detect the production of reactive oxygen species (ROS), we show that human and mouse monoclonal HA stalk-specific IgG antibodies are able to induce the production of ROS by neutrophils, while HA head-specific antibodies do not. Furthermore, our results indicate that the production of ROS is dependent on Fc receptor (FcR) engagement and phagocytosis. We went on to assess the ability of monoclonal HA stalk-specific IgA antibodies to induce ROS. Consistent with our findings for monoclonal IgGs, only HA stalk-specific IgA antibodies elicited ROS production by neutrophils. This induction is dependent on the engagement of FcαR1. Taken together, our findings describe a novel FcR-dependent effector function induced by HA stalk-specific IgG and IgA antibodies, and importantly, our studies shed light on the mechanisms by which HA stalk-specific antibodies achieve protection. PMID:27703076

  16. Structural Insights into Neonatal Fc Receptor-based Recycling Mechanisms

    PubMed Central

    Oganesyan, Vaheh; Damschroder, Melissa M.; Cook, Kimberly E.; Li, Qing; Gao, Changshou; Wu, Herren; Dall'Acqua, William F.

    2014-01-01

    We report the three-dimensional structure of human neonatal Fc receptor (FcRn) bound concurrently to its two known ligands. More particularly, we solved the crystal structure of the complex between human FcRn, wild-type human serum albumin (HSA), and a human Fc engineered for improved pharmacokinetics properties (Fc-YTE). The crystal structure of human FcRn bound to wild-type HSA alone is also presented. HSA domain III exhibits an extensive interface of contact with FcRn, whereas domain I plays a lesser role. A molecular explanation for the HSA recycling mechanism is provided with the identification of FcRn His161 as the only potential direct contributor to the corresponding pH-dependent process. At last, this study also allows an accurate structural definition of residues considered for decades as important to the human IgG/FcRn interaction and reveals Fc His310 as a significant contributor to pH-dependent binding. Finally, we explain various structural mechanisms by which several Fc mutations (including YTE) result in increased human IgG binding to FcRn. Our study provides an unprecedented relevant understanding of the molecular basis of human Fc interaction with human FcRn. PMID:24469444

  17. Leukocyte integrins: role in leukocyte recruitment and as therapeutic targets in inflammatory disease.

    PubMed

    Mitroulis, Ioannis; Alexaki, Vasileia I; Kourtzelis, Ioannis; Ziogas, Athanassios; Hajishengallis, George; Chavakis, Triantafyllos

    2015-03-01

    Infection or sterile inflammation triggers site-specific attraction of leukocytes. Leukocyte recruitment is a process comprising several steps orchestrated by adhesion molecules, chemokines, cytokines and endogenous regulatory molecules. Distinct adhesive interactions between endothelial cells and leukocytes and signaling mechanisms contribute to the temporal and spatial fine-tuning of the leukocyte adhesion cascade. Central players in the leukocyte adhesion cascade include the leukocyte adhesion receptors of the β2-integrin family, such as the αLβ2 and αMβ2 integrins, or of the β1-integrin family, such as the α4β1-integrin. Given the central involvement of leukocyte recruitment in different inflammatory and autoimmune diseases, the leukocyte adhesion cascade in general, and leukocyte integrins in particular, represent key therapeutic targets. In this context, the present review focuses on the role of leukocyte integrins in the leukocyte adhesion cascade. Experimental evidence that has implicated leukocyte integrins as targets in animal models of inflammatory disorders, such as experimental autoimmune encephalomyelitis, psoriasis, inflammatory bone loss and inflammatory bowel disease as well as preclinical and clinical therapeutic applications of antibodies that target leukocyte integrins in various inflammatory disorders are presented. Finally, we review recent findings on endogenous inhibitors that modify leukocyte integrin function, which could emerge as promising therapeutic targets.

  18. Alloantibody Generation and Effector Function Following Sensitization to Human Leukocyte Antigen

    PubMed Central

    Hickey, Michelle J.; Valenzuela, Nicole M.; Reed, Elaine F.

    2016-01-01

    Allorecognition is the activation of the adaptive immune system to foreign human leukocyte antigen (HLA) resulting in the generation of alloantibodies. Due to a high polymorphism, foreign HLA is recognized by the immune system following transplant, transfusion, or pregnancy resulting in the formation of the germinal center and the generation of long-lived alloantibody-producing memory B cells. Alloantibodies recognize antigenic epitopes displayed by the HLA molecule on the transplanted allograft and contribute to graft damage through multiple mechanisms, including (1) activation of the complement cascade resulting in the formation of the MAC complex and inflammatory anaphylatoxins, (2) transduction of intracellular signals leading to cytoskeletal rearrangement, growth, and proliferation of graft vasculature, and (3) immune cell infiltration into the allograft via FcγR interactions with the FC portion of the antibody. This review focuses on the generation of HLA alloantibody, routes of sensitization, alloantibody specificity, and mechanisms of antibody-mediated graft damage. PMID:26870045

  19. Weak protein interactions and pH- and temperature-dependent aggregation of human Fc1

    PubMed Central

    Wu, Haixia; Truncali, Kristopher; Ritchie, Julie; Kroe-Barrett, Rachel; Singh, Sanjaya; Robinson, Anne S; Roberts, Christopher J

    2015-01-01

    The Fc (fragment crystallizable) is a common structural region in immunoglobulin gamma (IgG) proteins, IgG-based multi-specific platforms, and Fc-fusion platform technologies. Changes in conformational stability, protein-protein interactions, and aggregation of NS0-produced human Fc1 were quantified experimentally as a function of pH (4 to 6) and temperature (30 to 77°C), using a combination of differential scanning calorimetry, laser light scattering, size-exclusion chromatography, and capillary electrophoresis. The Fc1 was O-glycosylated at position 3 (threonine), and confirmed to correspond to the intact IgG1 by comparison with Fc1 produced by cleavage of the parent IgG1. Changing the pH caused large effects for thermal unfolding transitions, but it caused surprisingly smaller effects for electrostatic protein-protein interactions. The aggregation behavior was qualitatively similar across different solution conditions, with soluble dimers and larger oligomers formed in most cases. Aggregation rates spanned approximately 5 orders of magnitude and could be divided into 2 regimes: (i) Arrhenius, unfolding-limited aggregation at temperatures near or above the midpoint-unfolding temperature of the CH2 domain; (ii) a non-Arrhenius regime at lower temperatures, presumably as a result of the temperature dependence of the unfolding enthalpy for the CH2 domain. The non-Arrhenius regime was most pronounced for lower temperatures. Together with the weak protein-protein repulsions, these highlight challenges that are expected for maintaining long-term stability of biotechnology products that are based on human Fc constructs. PMID:26267255

  20. Neutrophils Interact with Adenovirus Vectors via Fc Receptors and Complement Receptor 1

    PubMed Central

    Cotter, Matthew J.; Zaiss, Anne K.; Muruve, Daniel A.

    2005-01-01

    Neutrophils are effectors of the innate immune response to adenovirus vectors. Following the systemic administration of Cy2-labeled AdLuc in mice, flow cytometry and PCR analysis of liver leukocytes revealed that 25% of recruited neutrophils interacted with adenovirus vectors. In vitro, flow cytometry of human neutrophils incubated with Cy2-labeled AdLuc also demonstrated a significant interaction with adenovirus vectors. Fluorescence and electron microscopy confirmed vector internalization by neutrophils. The AdLuc-neutrophil interaction reduced vector transduction efficiency by more than 50% in coincubation assays in epithelium-derived cells. Adenovirus vector uptake by neutrophils occurred independently of coxsackievirus adenovirus receptor (CAR) and capsid RGD motifs, since neutrophils do not express CAR and uptake of the RGD-deleted vector AdL.PB* was similar to that of AdLuc. Furthermore, both AdLuc and AdL.PB* activated neutrophils and induced similar degrees of L-selectin shedding. Neutrophil uptake of AdLuc was dependent on the presence of complement and antibodies, since the interaction between AdLuc and neutrophils was significantly reduced when they were incubated in immunoglobulin G-depleted or heat-inactivated human serum. Blocking of complement receptor 1 (CD35) but not complement receptor 3 (CD11b/CD18) significantly reduced neutrophil uptake of AdLuc. Blocking of FcγRI (CD64), FcγRII (CD32), and FcγRIII (CD16) individually or together also reduced neutrophil uptake of AdLuc, although less than blocking of CD35 alone. Combined CR1 and Fc receptor blockade synergistically inhibited neutrophil-AdLuc interactions close to baseline. These results demonstrate opsonin-dependent adenovirus vector interactions with neutrophils and their corresponding receptors. PMID:16282462

  1. Functional characteristics of enhanced Fc receptor expression of beta 2 integrin-deficient bovine mononuclear phagocytes.

    PubMed

    Nagahata, H; Higuchi, H; Goji, N; Noda, H; Kuwabara, M

    1996-01-01

    Fc receptor expression, cytoplasmic Ca2+ signaling, chemiluminescent (CL) response, and electron spin resonance (ESR) combined with spin trapping of blood mononuclear phagocytes from control heifers and a heifer with leukocyte adhesion deficiency (LAD) were evaluated to elucidate the relationships between complement receptor type 3 (CR3) and Fc receptor expression and their functional responses. The mean fluorescence intensity of fluorescein isothiocyanate (FITC)-conjugated anti-bovine IgG bound to mononuclear phagocytes from the heifer with LAD was 1.8-fold higher than that of control heifers. The mean increments of cytoplasmic Ca2+ concentrations of mononuclear phagocytes from the heifer with LAD stimulated with OPZ, Agg-IgG, and PMA were 39.4 (P < 0.05), 118, and 71.6% compared with those of control heifers. A 1.27-fold increase in the CL response relative to control heifers was detected when mononuclear phagocytes from the heifer with LAD were stimulated with Agg-IgG. The OPZ-induced CL response of mononuclear phagocytes from the heifer with LAD was significantly (P < 0.05) decreased, whereas the PMA-induced CL response was similar to that of control heifers. The ESR spectrum of mononuclear phagocytes from the heifer with LAD was increased when stimulated with Agg-IgG, and was impaired when stimulated by OPZ compared with that of control heifers. The ESR spectrum of mononuclear phagocytes stimulated with PMA was similar in control heifers and the heifer with LAD. Fc receptors on mononuclear phagocytes from the heifer with LAD were enhanced, and their cytoplasmic Ca2+ signaling, CL response, and ESR-spin trapping when stimulated with Agg-IgG and OPZ appeared to be associated with enhanced Fc receptors. PMID:8805104

  2. CD44 Antibody Inhibition of Macrophage Phagocytosis Targets Fcγ Receptor- and Complement Receptor 3-Dependent Mechanisms.

    PubMed

    Amash, Alaa; Wang, Lin; Wang, Yawen; Bhakta, Varsha; Fairn, Gregory D; Hou, Ming; Peng, Jun; Sheffield, William P; Lazarus, Alan H

    2016-04-15

    Targeting CD44, a major leukocyte adhesion molecule, using specific Abs has been shown beneficial in several models of autoimmune and inflammatory diseases. The mechanisms contributing to the anti-inflammatory effects of CD44 Abs, however, remain poorly understood. Phagocytosis is a key component of immune system function and can play a pivotal role in autoimmune states where CD44 Abs have shown to be effective. In this study, we show that the well-known anti-inflammatory CD44 Ab IM7 can inhibit murine macrophage phagocytosis of RBCs. We assessed three selected macrophage phagocytic receptor systems: Fcγ receptors (FcγRs), complement receptor 3 (CR3), and dectin-1. Treatment of macrophages with IM7 resulted in significant inhibition of FcγR-mediated phagocytosis of IgG-opsonized RBCs. The inhibition of FcγR-mediated phagocytosis was at an early stage in the phagocytic process involving both inhibition of the binding of the target RBC to the macrophages and postbinding events. This CD44 Ab also inhibited CR3-mediated phagocytosis of C3bi-opsonized RBCs, but it did not affect the phagocytosis of zymosan particles, known to be mediated by the C-type lectin dectin-1. Other CD44 Abs known to have less broad anti-inflammatory activity, including KM114, KM81, and KM201, did not inhibit FcγR-mediated phagocytosis of RBCs. Taken together, these findings demonstrate selective inhibition of FcγR and CR3-mediated phagocytosis by IM7 and suggest that this broadly anti-inflammatory CD44 Ab inhibits these selected macrophage phagocytic pathways. The understanding of the immune-regulatory effects of CD44 Abs is important in the development and optimization of therapeutic strategies for the potential treatment of autoimmune conditions.

  3. CD44 Antibody Inhibition of Macrophage Phagocytosis Targets Fcγ Receptor- and Complement Receptor 3-Dependent Mechanisms.

    PubMed

    Amash, Alaa; Wang, Lin; Wang, Yawen; Bhakta, Varsha; Fairn, Gregory D; Hou, Ming; Peng, Jun; Sheffield, William P; Lazarus, Alan H

    2016-04-15

    Targeting CD44, a major leukocyte adhesion molecule, using specific Abs has been shown beneficial in several models of autoimmune and inflammatory diseases. The mechanisms contributing to the anti-inflammatory effects of CD44 Abs, however, remain poorly understood. Phagocytosis is a key component of immune system function and can play a pivotal role in autoimmune states where CD44 Abs have shown to be effective. In this study, we show that the well-known anti-inflammatory CD44 Ab IM7 can inhibit murine macrophage phagocytosis of RBCs. We assessed three selected macrophage phagocytic receptor systems: Fcγ receptors (FcγRs), complement receptor 3 (CR3), and dectin-1. Treatment of macrophages with IM7 resulted in significant inhibition of FcγR-mediated phagocytosis of IgG-opsonized RBCs. The inhibition of FcγR-mediated phagocytosis was at an early stage in the phagocytic process involving both inhibition of the binding of the target RBC to the macrophages and postbinding events. This CD44 Ab also inhibited CR3-mediated phagocytosis of C3bi-opsonized RBCs, but it did not affect the phagocytosis of zymosan particles, known to be mediated by the C-type lectin dectin-1. Other CD44 Abs known to have less broad anti-inflammatory activity, including KM114, KM81, and KM201, did not inhibit FcγR-mediated phagocytosis of RBCs. Taken together, these findings demonstrate selective inhibition of FcγR and CR3-mediated phagocytosis by IM7 and suggest that this broadly anti-inflammatory CD44 Ab inhibits these selected macrophage phagocytic pathways. The understanding of the immune-regulatory effects of CD44 Abs is important in the development and optimization of therapeutic strategies for the potential treatment of autoimmune conditions. PMID:26944929

  4. Leukocyte chemoattractant receptors in human disease pathogenesis.

    PubMed

    Zabel, Brian A; Rott, Alena; Butcher, Eugene C

    2015-01-01

    Combinations of leukocyte attractant ligands and cognate heptahelical receptors specify the systemic recruitment of circulating cells by triggering integrin-dependent adhesion to endothelial cells, supporting extravasation, and directing specific intratissue localization via gradient-driven chemotaxis. Chemoattractant receptors also control leukocyte egress from lymphoid organs and peripheral tissues. In this article, we summarize the fundamental mechanics of leukocyte trafficking, from the evolution of multistep models of leukocyte recruitment and navigation to the regulation of chemoattractant availability and function by atypical heptahelical receptors. To provide a more complete picture of the migratory circuits involved in leukocyte trafficking, we integrate a number of nonchemokine chemoattractant receptors into our discussion. Leukocyte chemoattractant receptors play key roles in the pathogenesis of autoimmune diseases, allergy, inflammatory disorders, and cancer. We review recent advances in our understanding of chemoattractant receptors in disease pathogenesis, with a focus on genome-wide association studies in humans and the translational implications of mechanistic studies in animal disease models.

  5. Gamma-gamma colliders

    SciTech Connect

    Kim, K.J.; Sessler, A.

    1996-06-01

    Gamma-gamma colliders make intense beams of gamma rays and have them collide so as to make elementary particles. The authors show, in this article, that constructing a gamma-gamma collider as an add-on to an electron-positron linear collider is possible with present technology and that it does not require much additional cost. Furthermore, they show that the resulting capability is very interesting from a particle physics point of view. An overview of a linear collider, with a second interaction region devoted to {gamma}{gamma} collisions is shown.

  6. Fc receptor-mediated phagocytosis, superoxide production and calcium signaling of beta 2 integrin-deficient bovine neutrophils.

    PubMed

    Nagahata, H; Sawada, C; Higuchi, H; Teraoka, H; Yamaguchi, M

    1997-01-01

    Fc receptor for immunoglobulin G-mediated phagocytosis, superoxide production and intracellular calcium ([Ca2+]i) signaling of complement receptor type 3 (CR3)-deficient neutrophils from a heifer with leukocyte adhesion deficiency (BLAD) were compared to those of control heifers. The mean phagocytic activity of IgG-coated yeasts and aggregated bovine IgG (Agg-IgG)-induced superoxide production of CR3-deficient neutrophils were 10% and 77.9%, respectively, of those of control neutrophils. The [Ca2+]i signals in CR3-deficient neutrophils stimulated with Agg-IgG or concanavalin A were different with mean peak [Ca2+]i concentrations of 78% and 41.9%, respectively, of those of control neutrophils. These findings suggest that Fc receptor-mediated neutrophil functions are closely dependent on the presence of CR3 (CD11b/CD18) on the neutrophil cell surfaces. PMID:9343828

  7. Kinetics of leukocyte sequestration in the lungs of acutely septic primates: A study using sup 111 In-labeled autologous leukocytes

    SciTech Connect

    Hangen, D.H.; Segall, G.M.; Harney, E.W.; Stevens, J.H.; McDougall, I.R.; Raffin, T.A. )

    1990-03-01

    To further clarify the role of leukocytes in the pathogenesis of ARDS, we studied the localization and kinetics of leukocyte migration using 111In-labeled autologous white cell scans ({sup 111}In wbc scans) in four primates made acutely septic with infusions of Escherichia coli. Whole body images were obtained with a gamma camera and were acquired on computer every 15 min beginning immediately after the E. coli infusion. Simultaneous measurements of C5a and peripheral blood leukocyte count were also obtained. Within 5 min of initiating sepsis, three major events occurred: complement activation as measured by the production of C5a, a profound fall in peripheral leukocyte count, and a significant increase in the sequestration of leukocytes in the lungs. The pulmonary sequestration reached a peak at 15 min with a mean of 152% of baseline activity. This sequestration consisted of a population that was predominantly neutrophils. Damage to the pulmonary capillary endothelium was demonstrated by an increase in extravascular lung water. The results support a role for neutrophils and complement as mediators in the pathogenesis of ARDS.

  8. The leukocyte response to fluid stress

    PubMed Central

    Moazzam, Fariborz; DeLano, Frank A.; Zweifach, Benjamin W.; Schmid-Schönbein, Geert W.

    1997-01-01

    Leukocyte migration from a hemopoietic pool across marrow endothelium requires active pseudopod formation and adhesion. Leukocytes rarely show pseudopod formation while in circulation. At question then is the mechanism that serves to minimize leukocyte pseudopod formation in the circulation. We tested the hypothesis that fluid shear stress acts to prevent pseudopod formation. When individual human leukocytes (neutrophils, monocytes) spreading on glass surfaces in vitro were subjected to fluid shear stress (≈1 dyn/cm2), an instantaneous retraction of pseudopods was observed. Removal of the fluid shear stress in turn led to the return of pseudopod projection and cell spreading. When steady shear stress was prolonged over several minutes, leukocyte swelling occurs together with an enhanced random motion of cytoplasmic granules and a reduction of cytoplasmic stiffness. The response to shear stress could be suppressed by K+ channel blockers and chelation of external Ca2+. In rat mesentery microvessels after occlusion, circulating leukocytes project pseudopods in free suspension or when attached to the endothelium, even though immediately after occlusion only few pseudopods were present. When flow was restored, pseudopods on adhering leukocytes were retracted and then the cells began to roll and detach from the endothelium. In conclusion, plasma shear stress in the circulation serves to reduce pseudopod projection and adhesion of circulating leukocytes and vice versa reduction of shear stress leads to pseudopod projection and spreading of leukocytes on the endothelium. PMID:9144238

  9. Transepithelial Transport of Fc -Targeted Nanoparticles by the Neonatal Fc Receptor for Oral Delivery

    PubMed Central

    Pridgen, Eric M.; Alexis, Frank; Kuo, Timothy T.; Levy-Nissenbaum, Etgar; Karnik, Rohit; Blumberg, Richard S.; Langer, Robert; Farokhzad, Omid C.

    2014-01-01

    Nanoparticles are poised to have a tremendous impact on the treatment of many diseases, but their broad application is limited because currently they can only be administered by parenteral methods. Oral administration of nanoparticles is preferred but remains a challenge because transport across the intestinal epithelium is limited. Here, we show that nanoparticles targeted to the neonatal Fc receptor (FcRn), which is known to mediate the transport of IgG antibodies across epithelial barriers, are efficiently transported across the intestinal epithelium using both in vitro and in vivo models. In mice, orally administered FcRn-targeted nanoparticles crossed the intestinal epithelium and reached systemic circulation with a mean absorption efficiency of 13.7%*h compared with only 1.2%*h for non-targeted nanoparticles. In addition, targeted nanoparticles containing insulin as a model nanoparticle-based therapy for diabetes were orally administered at a clinically relevant insulin dose of 1.1 U/kg and elicited a prolonged hypoglycemic response in wild-type mice. This effect was abolished in FcRn knockout mice, indicating the enhanced nanoparticle transport was due specifically to FcRn. FcRn-targeted nanoparticles may have a major impact on the treatment of many diseases by enabling drugs currently limited by low bioavailability to be efficiently delivered though oral administration. PMID:24285486

  10. Transforming Growth Factor-β-Activated Kinase 1 Is Required for Human FcγRIIIb-Induced Neutrophil Extracellular Trap Formation.

    PubMed

    Alemán, Omar Rafael; Mora, Nancy; Cortes-Vieyra, Ricarda; Uribe-Querol, Eileen; Rosales, Carlos

    2016-01-01

    Neutrophils (PMNs) are the most abundant leukocytes in the blood. PMN migrates from the circulation to sites of infection where they are responsible for antimicrobial functions. PMN uses phagocytosis, degranulation, and formation of neutrophil extracellular traps (NETs) to kill microbes. Several stimuli, including bacteria, fungi, and parasites, and some pharmacological compounds, such as Phorbol 12-myristate 13-acetate (PMA), are efficient inducers of NETs. Antigen-antibody complexes are also capable of inducing NET formation. Recently, it was reported that FcγRIIIb cross-linking induced NET formation similarly to PMA stimulation. Direct cross-linking of FcγRIIA or integrins did not promote NET formation. FcγRIIIb-induced NET formation presented different kinetics from PMA-induced NET formation, suggesting differences in signaling. Because FcγRIIIb also induces a strong activation of extracellular signal-regulated kinase (ERK) and nuclear factor Elk-1, and the transforming growth factor-β-activated kinase 1 (TAK1) has recently been implicated in ERK signaling, in the present report, we explored the role of TAK1 in the signaling pathway activated by FcγRIIIb leading to NET formation. FcγRIIIb was stimulated by specific monoclonal antibodies, and NET formation was evaluated in the presence or absence of pharmacological inhibitors. The antibiotic LL Z1640-2, a selective inhibitor of TAK1 prevented FcγRIIIb-induced, but not PMA-induced NET formation. Both PMA and FcγRIIIb cross-linking induced phosphorylation of ERK. But, LL Z1640-2 only inhibited the FcγRIIIb-mediated activation of ERK. Also, only FcγRIIIb, similarly to transforming growth factor-β-induced TAK1 phosphorylation. A MEK (ERK kinase)-specific inhibitor was able to prevent ERK phosphorylation induced by both PMA and FcγRIIIb. These data show for the first time that FcγRIIIb cross-linking activates TAK1, and that this kinase is required for triggering the MEK/ERK signaling pathway to NETosis

  11. Transforming Growth Factor-β-Activated Kinase 1 Is Required for Human FcγRIIIb-Induced Neutrophil Extracellular Trap Formation

    PubMed Central

    Alemán, Omar Rafael; Mora, Nancy; Cortes-Vieyra, Ricarda; Uribe-Querol, Eileen; Rosales, Carlos

    2016-01-01

    Neutrophils (PMNs) are the most abundant leukocytes in the blood. PMN migrates from the circulation to sites of infection where they are responsible for antimicrobial functions. PMN uses phagocytosis, degranulation, and formation of neutrophil extracellular traps (NETs) to kill microbes. Several stimuli, including bacteria, fungi, and parasites, and some pharmacological compounds, such as Phorbol 12-myristate 13-acetate (PMA), are efficient inducers of NETs. Antigen–antibody complexes are also capable of inducing NET formation. Recently, it was reported that FcγRIIIb cross-linking induced NET formation similarly to PMA stimulation. Direct cross-linking of FcγRIIA or integrins did not promote NET formation. FcγRIIIb-induced NET formation presented different kinetics from PMA-induced NET formation, suggesting differences in signaling. Because FcγRIIIb also induces a strong activation of extracellular signal-regulated kinase (ERK) and nuclear factor Elk-1, and the transforming growth factor-β-activated kinase 1 (TAK1) has recently been implicated in ERK signaling, in the present report, we explored the role of TAK1 in the signaling pathway activated by FcγRIIIb leading to NET formation. FcγRIIIb was stimulated by specific monoclonal antibodies, and NET formation was evaluated in the presence or absence of pharmacological inhibitors. The antibiotic LL Z1640-2, a selective inhibitor of TAK1 prevented FcγRIIIb-induced, but not PMA-induced NET formation. Both PMA and FcγRIIIb cross-linking induced phosphorylation of ERK. But, LL Z1640-2 only inhibited the FcγRIIIb-mediated activation of ERK. Also, only FcγRIIIb, similarly to transforming growth factor-β-induced TAK1 phosphorylation. A MEK (ERK kinase)-specific inhibitor was able to prevent ERK phosphorylation induced by both PMA and FcγRIIIb. These data show for the first time that FcγRIIIb cross-linking activates TAK1, and that this kinase is required for triggering the MEK/ERK signaling pathway to

  12. Long-term carcinogenicity bioassays on three chlorofluorocarbons (trichlorofluoromethane, FC11; dichlorodifluoromethane, FC12; chlorodifluoromethane, FC22) administered by inhalation to Sprague-Dawley rats and Swiss mice

    SciTech Connect

    Maltoni, C.; Lefemine, G.; Tovoli, D.; Perino, G.

    1988-01-01

    Three propellant chlorofluorocarbons, namely trichlorofluoromethane (FC11), dichlorodifluoromethane (FC12), and chlorodifluoromethane (FC22) were administered by inhalation at a concentration of 5000, 1000 and 0 ppm, 4 hours daily, 5 days weekly, for 104 and 78 weeks, to rats and mice, respectively. The animals were kept under observation until spontaneous death. Under the experimental conditions, all three compounds failed to show any carcinogenic effects.

  13. Long-term carcinogenicity bioassays on three chlorofluorocarbons (trichlorofluoromethane, FC11; dichlorodifluoromethane, FC12; chlorodifluoromethane, FC22) administered by inhalation to Sprague-Dawley rats and Swiss mice.

    PubMed

    Maltoni, C; Lefemine, G; Tovoli, D; Perino, G

    1988-01-01

    Three propellant chlorofluorocarbons, namely trichlorofluoromethane (FC11), dichlorodifluoromethane (FC12), and chlorodifluoromethane (FC22) were administered by inhalation at a concentration of 5000, 1000 and 0 ppm, 4 hours daily, 5 days weekly, for 104 and 78 weeks, to rats and mice, respectively. The animals were kept under observation until spontaneous death. Under the experimental conditions, all three compounds failed to show any carcinogenic effects.

  14. Characterization of the rabbit neonatal Fc receptor (FcRn) and analyzing the immunophenotype of the transgenic rabbits that overexpresses FcRn.

    PubMed

    Catunda Lemos, Ana Paula; Cervenak, Judit; Bender, Balázs; Hoffmann, Orsolya Ivett; Baranyi, Mária; Kerekes, Andrea; Farkas, Anita; Bosze, Zsuzsanna; Hiripi, László; Kacskovics, Imre

    2012-01-01

    The neonatal Fc receptor (FcRn) regulates IgG and albumin homeostasis, mediates maternal IgG transport, takes an active role in phagocytosis, and delivers antigen for presentation. We have previously shown that overexpression of FcRn in transgenic mice significantly improves the humoral immune response. Because rabbits are an important source of polyclonal and monoclonal antibodies, adaptation of our FcRn overexpression technology in this species would bring significant advantages. We cloned the full length cDNA of the rabbit FcRn alpha-chain and found that it is similar to its orthologous analyzed so far. The rabbit FcRn - IgG contact residues are highly conserved, and based on this we predicted pH dependent interaction, which we confirmed by analyzing the pH dependent binding of FcRn to rabbit IgG using yolk sac lysates of rabbit fetuses by Western blot. Using immunohistochemistry, we detected strong FcRn staining in the endodermal cells of the rabbit yolk sac membrane, while the placental trophoblast cells and amnion showed no FcRn staining. Then, using BAC transgenesis we generated transgenic rabbits carrying and overexpressing a 110 kb rabbit genomic fragment encoding the FcRn. These transgenic rabbits--having one extra copy of the FcRn when hemizygous and two extra copies when homozygous--showed improved IgG protection and an augmented humoral immune response when immunized with a variety of different antigens. Our results in these transgenic rabbits demonstrate an increased immune response, similar to what we described in mice, indicating that FcRn overexpression brings significant advantages for the production of polyclonal and monoclonal antibodies.

  15. Long-term carcinogenicity bioassays on three chlorofluorocarbons (trichlorofluoromethane, FC11; dichlorodifluoromethane, FC12; chlorodifluoromethane, FC22) administered by inhalation to Sprague-Dawley rats and Swiss mice.

    PubMed

    Maltoni, C; Lefemine, G; Tovoli, D; Perino, G

    1988-01-01

    Three propellant chlorofluorocarbons, namely trichlorofluoromethane (FC11), dichlorodifluoromethane (FC12), and chlorodifluoromethane (FC22) were administered by inhalation at a concentration of 5000, 1000 and 0 ppm, 4 hours daily, 5 days weekly, for 104 and 78 weeks, to rats and mice, respectively. The animals were kept under observation until spontaneous death. Under the experimental conditions, all three compounds failed to show any carcinogenic effects. PMID:3389660

  16. The multifaceted role of PIP2 in leukocyte biology.

    PubMed

    Tuosto, Loretta; Capuano, Cristina; Muscolini, Michela; Santoni, Angela; Galandrini, Ricciarda

    2015-12-01

    Phosphatidylinositol 4,5-bisphosphate (PIP2) represents about 1 % of plasma membrane phospholipids and behaves as a pleiotropic regulator of a striking number of fundamental cellular processes. In recent years, an increasing body of literature has highlighted an essential role of PIP2 in multiple aspects of leukocyte biology. In this emerging picture, PIP2 is envisaged as a signalling intermediate itself and as a membrane-bound regulator and a scaffold of proteins with specific PIP2 binding domains. Indeed PIP2 plays a key role in several functions. These include directional migration in neutrophils, integrin-dependent adhesion in T lymphocytes, phagocytosis in macrophages, lysosomes secretion and trafficking at immune synapse in cytolytic effectors and secretory cells, calcium signals and gene transcription in B lymphocytes, natural killer cells and mast cells. The coordination of these different aspects relies on the spatio-temporal organisation of distinct PIP2 pools, generated by the main PIP2 generating enzyme, phosphatidylinositol 4-phosphate 5-kinase (PIP5K). Three different isoforms of PIP5K, named α, β and γ, and different splice variants have been described in leukocyte populations. The isoform-specific coupling of specific isoforms of PIP5K to different families of activating receptors, including integrins, Fc receptors, toll-like receptors and chemokine receptors, is starting to be reported. Furthermore, PIP2 is turned over by multiple metabolising enzymes including phospholipase C (PLC) γ and phosphatidylinositol 3-kinase (PI3K) which, along with Rho family small G proteins, is widely involved in strategic functions within the immune system. The interplay between PIP2, lipid-modifying enzymes and small G protein-regulated signals is also discussed.

  17. Glycobiology of leukocyte trafficking in inflammation.

    PubMed

    Wright, Rachael D; Cooper, Dianne

    2014-12-01

    To fulfill their potential, leukocytes must be able to exit the vasculature and reach the site of inflammation within the tissue. This process of leukocyte extravasation is a tightly regulated sequence of events that is governed by a host of cell adhesion molecules, cytokines, chemokines and lipid mediators. Of major importance to this process and the function of many of the proteins and lipids involved is the posttranslational modification of these moieties by glycosylation. The glycosylation process is coordinated by multiple enzymes that add and remove saccharides to/from glycan structures on proteins and lipids, resulting in a unique molecular signature that affords specificity to the molecules involved in leukocyte recruitment. This review will discuss how glycosylation impacts the function of these key molecules involved in the recruitment of leukocytes during inflammation and the function of specific lectins (carbohydrate-binding proteins) that have a role in leukocyte trafficking.

  18. Coefficient of thermal expansion of Fluorinert FC-86

    SciTech Connect

    Pane, A.J.

    1982-05-01

    The cubical coefficient of thermal expansion (CTE) pf Fluorinert Fluid, FC-86 was measured before and after degassing. The CTE for the FC-86 before degassing is: ..beta.. = 9.282 x 10/sup -6/T + 1.6115 x 10/sup -3/ with T = -30 to + 75/sup 0/C. The CTE for the FC-86 (degassed) is: ..beta.. = 6.133 x 10/sup -6/T + 1.7643 x 10/sup -3/ with T = -30 to + 75/sup 0/C. Measurements were also made of the pressures required to prevent cavitation in the degassed FC-86 and in FC-86 containing 2.4 volume percent of air. At 71.0/sup 0/C the cavitational pressure of degassed FC-86 is 1285 torr and at 73.8/sup 0/C the cavitational pressure of the FC-86 containing 2.4 volume percent of air is 1229 torr.

  19. NFκB induces overexpression of bovine FcRn

    PubMed Central

    Cervenak, Judit; Doleschall, Márton; Bender, Balázs; Mayer, Balázs; Schneider, Zita; Doleschall, Zoltán; Zhao, Yaofeng; Bősze, Zsuzsanna; Hammarström, Lennart; Oster, Wolfgang; Kacskovics, Imre

    2013-01-01

    Among the many functions of the neonatal Fc receptor (FcRn) for IgG, it binds to IgG-opsonized antigen complexes and propagates their traffic into lysosomes where antigen processing occurs. We previously reported that transgenic (Tg) mice and rabbits that carry multiple copies and overexpress FcRn have augmented humoral immune responses. Nuclear factor-kappa B (NFκB) is a critical molecule in the signaling cascade in the immune response. NFκB induces human FcRn expression and our previous in silico analysis suggested NFκB binding sites in the promoter region of the bovine (b) FcRn α-chain gene (FCGRT). Here, we report the identification of three NFκB transcription binding sites in the promoter region of this gene using luciferase reporter gene technology, electromobility shift assay and supershift analysis. Stimulation of primary bovine endothelial cells with the Toll-like receptor-4 ligand lipopolysaccharide (LPS), which mediates its effect via NFκB, resulted in rapid upregulation of the bFcRn expression and a control gene, bovine E-selectin. This rapid bFcRn gene induction was also observed in the spleen of bFcRn Tg mice treated with intraperitoneally injected LPS, analyzed by northern blot analysis. Finally, NFκB-mediated bFcRn upregulation was confirmed at the protein level in macrophages isolated from the bFcRn Tg mice using flow cytometry with a newly developed FcRn specific monoclonal antibody that does not cross-react with the mouse FcRn. We conclude that NFκB regulates bFcRn expression and thus optimizes its functions, e.g., in the professional antigen presenting cells, and contributes to the much augmented humoral immune response in the bFcRn Tg mice. PMID:24492342

  20. Complement and immunoglobulins stimulate superoxide production by human leukocytes independently of phagocytosis.

    PubMed Central

    Goldstein, I M; Roos, D; Kaplan, H B; Weissmann, G

    1975-01-01

    Human peripheral blood polymorphonuclear leukocytes, when exposed to appropriate stimuli, generate significant amounts of superoxide anion (O-.2), a highly reactive molecule which is possibly involved in bacterial killing. Since the subcellular localization and mechanism of activation of O-.2 generating systems are unknown, we have investigated superoxide dismutase-inhibitable cytochrome c reduction (attributable to O-.2) by, and lysosomal enzyme release from, normal polymorphonuclear leukocytes and cells rendered incapable of ingesting particles by treatment with cytochalasin B. Neither phagocytosis nor lysosomal degranulation were prerequisites for enhanced O-.2 generation. Cytochalasin B-treated cells exposed to (a) serum-treated zymosan, a C3b receptor stimulus; (b) heat aggregated human IgG, an Fc receptor stimulus; and (c) the complement component, C5a, generated enhanced amounts of O-.2 in a time and concentration-dependent fashion. These cells also responded by releasing lysosomal enzymes, but there was no correlation between the ability of any immune reactant to provoke enzyme release and its ability to stimulate O-.2 generation. The three stimuli also enhanced O-.2 generation by normal (untreated) polymorphonuclear leukocytes, but only serum-treated zymosan and aggregated IgG were capable of provoking lysosomal enzyme release from normal cells. Untreated zymosan and native IgG neither stimulated O-.2 production nor provoked lysomal enzyme release. Since enhanced O-.2 production was stimulated by immune reactants in the absence of phagocytosis, the O-.2 generating system is very likely associated with the external plasma membrane of the polymorphonuclear leukocyte. Leukocyte membrane receptors for complement and immunoglobulins may therefore not only serve in particle recognition but also may initiate biochemical events which accompany phagocytosis and killing. PMID:171281

  1. Kinetics of the appearance of Fc epsilon RI-bearing cells in interleukin-3-dependent mouse bone marrow cultures: correlation with histamine content and mast cell maturation.

    PubMed

    Rottem, M; Barbieri, S; Kinet, J P; Metcalfe, D D

    1992-02-15

    While it is known that mast cells arise from pluripotential hematopoietic cells and express their mature phenotypes in tissues, the sequence of events in maturation is incompletely understood. To study early mast cells, we sorted cells from interleukin-3 (IL-3)-dependent mouse bone marrow cultures on the basis of Fc epsilon RI and examined their morphology, histamine content, and growth characteristics. Flow cytometric analysis and sort showed that the Fc epsilon RI-bearing (Fc epsilon RI+) cells increased from 0% on day 0 to 90% by day 21 and that the total number of Fc epsilon RI+ cells increased from 0 at the start of culture to 3.75 x 10(5) cells by day 21 from an initial population of 1 x 10(5) cells. The dissociation rate of 125I-labeled IgE from early cultured cells resembled the dissociation rate of mouse IgE from mature murine mast cells. Mean fluorescence intensity increased over time, reflecting an increase in IgE receptor density. Fc epsilon RI+ cells were also positive for Fc gamma RII/III. Morphologic studies showed gradual acquisition of metachromatic granules in the Fc epsilon RI+ cells, which was paralleled by an increase in histamine content. Sorted Fc epsilon RI+ cells, when placed in liquid suspension culture, gave rise to pure mast cell populations. Fc epsilon RI+ cells sorted at day 3 and cultured in agarose with IL-3 gave rise to 4,800 small and 150 medium-size mast cell colony-forming units per 10(6) cells, while Fc epsilon RI- cells gave rise to 23 medium-size and 49 large mast cell colony-forming units per 10(6) cells. Fc epsilon RI+ cells grown in granulocyte-macrophage colony-stimulating factor (CSF) or macrophage-CSF did not give rise to colony-forming units. These results show that Fc epsilon RI+ cells have proliferative potential, but that there also is a population of mast cell progenitor cells that have not yet expressed Fc epsilon RI, and such individual progenitor cells have greater potential for proliferation than cells that

  2. Enhanced FcRn-dependent transepithelial delivery of IgG by Fc-engineering and polymerization.

    PubMed

    Foss, Stian; Grevys, Algirdas; Sand, Kine Marita Knudsen; Bern, Malin; Blundell, Pat; Michaelsen, Terje E; Pleass, Richard J; Sandlie, Inger; Andersen, Jan Terje

    2016-02-10

    Monoclonal IgG antibodies (Abs) are used extensively in the clinic to treat cancer and autoimmune diseases. In addition, therapeutic proteins are genetically fused to the constant Fc part of IgG. In both cases, the Fc secures a long serum half-life and favourable pharmacokinetics due to its pH-dependent interaction with the neonatal Fc receptor (FcRn). FcRn also mediates transport of intact IgG across polarized epithelial barriers, a pathway that is attractive for delivery of Fc-containing therapeutics. So far, no study has thoroughly compared side-by-side how IgG and different Fc-fusion formats are transported across human polarizing epithelial cells. Here, we used an in vitro cellular transport assay based on the human polarizing epithelial cell line (T84) in which both IgG1 and Fc-fusions were transported in an FcRn-dependent manner. Furthermore, we found that the efficacy of transport was dependent on the format. We demonstrate that transepithelial delivery could be enhanced by Fc-engineering for improved FcRn binding as well as by Fc-polymerization. In both cases, transport was driven by pH-dependent binding kinetics and the pH at the luminal side. Hence, efficient transcellular delivery of IgG-based drugs across human epithelial cells requires optimal pH-dependent FcRn binding that can be manipulated by avidity and Fc-engineering, factors that should inspire the design of future therapeutics targeted for transmucosal delivery. PMID:26718855

  3. The role of leukocytes in thrombosis.

    PubMed

    Swystun, Laura L; Liaw, Patricia C

    2016-08-11

    In recent years, the traditional view of the hemostatic system as being regulated by a coagulation factor cascade coupled with platelet activation has been increasingly challenged by new evidence that activation of the immune system strongly influences blood coagulation and pathological thrombus formation. Leukocytes can be induced to express tissue factor and release proinflammatory and procoagulant molecules such as granular enzymes, cytokines, and damage-associated molecular patterns. These mediators can influence all aspects of thrombus formation, including platelet activation and adhesion, and activation of the intrinsic and extrinsic coagulation pathways. Leukocyte-released procoagulant mediators increase systemic thrombogenicity, and leukocytes are actively recruited to the site of thrombus formation through interactions with platelets and endothelial cell adhesion molecules. Additionally, phagocytic leukocytes are involved in fibrinolysis and thrombus resolution, and can regulate clearance of platelets and coagulation factors. Dysregulated activation of leukocyte innate immune functions thus plays a role in pathological thrombus formation. Modulation of the interactions between leukocytes or leukocyte-derived procoagulant materials and the traditional hemostatic system is an attractive target for the development of novel antithrombotic strategies. PMID:27354721

  4. Mouse and human FcR effector functions.

    PubMed

    Bruhns, Pierre; Jönsson, Friederike

    2015-11-01

    Mouse and human FcRs have been a major focus of attention not only of the scientific community, through the cloning and characterization of novel receptors, and of the medical community, through the identification of polymorphisms and linkage to disease but also of the pharmaceutical community, through the identification of FcRs as targets for therapy or engineering of Fc domains for the generation of enhanced therapeutic antibodies. The availability of knockout mouse lines for every single mouse FcR, of multiple or cell-specific--'à la carte'--FcR knockouts and the increasing generation of hFcR transgenics enable powerful in vivo approaches for the study of mouse and human FcR biology. This review will present the landscape of the current FcR family, their effector functions and the in vivo models at hand to study them. These in vivo models were recently instrumental in re-defining the properties and effector functions of FcRs that had been overlooked or discarded from previous analyses. A particular focus will be made on the (mis)concepts on the role of high-affinity IgG receptors in vivo and on results from antibody engineering to enhance or abrogate antibody effector functions mediated by FcRs. PMID:26497511

  5. Fcγ Receptors and Ligands and Cardiovascular Disease

    PubMed Central

    Tanigaki, Keiji; Sundgren, Nathan; Khera, Amit; Vongpatanasin, Wanpen; Mineo, Chieko; Shaul, Philip W.

    2015-01-01

    Fcγ receptors (FcγR) classically modulate intracellular signaling upon binding of the Fc region of IgG in immune response cells. How FcγR and their ligands impact cardiovascular health and disease has recently been interrogated in both preclinical and clinical studies. The stimulation of activating FcγR in endothelial cells, vascular smooth muscle cells and monocytes/macrophages causes a variety of cellular responses that may contribute to vascular disease pathogenesis. Stimulation of the lone inhibitory FγcR, FcγRIIB, also has adverse consequences in endothelial cells, antagonizing NO production and reparative mechanisms. In preclinical disease models, activating FcγR promote atherosclerosis whereas FcγRIIB is protective, and activating FcγR also enhance thrombotic and non-thrombotic vascular occlusion. The FcγR ligand C-reactive protein (CRP) has undergone intense study. Although in rodents CRP does not impact atherosclerosis, it causes hypertension and insulin resistance and worsens myocardial infarction. Massive data has accumulated indicating an association between increases in circulating CRP and coronary heart disease in humans. However, Mendelian randomization studies reveal that CRP is not likely a disease mediator. CRP genetics and hypertension warrants further investigation. Studies to date of genetic variants of activating FcγR are insufficient to implicate the receptors in coronary heart disease pathogenesis in humans. However, a link between FcγRIIB and human hypertension may be emerging. Further knowledge of the vascular biology of FcγR and their ligands will potentially enhance our understanding of cardiovascular disorders, particularly in patients whose greater predisposition for disease is not explained by traditional risk factors, such as individuals with autoimmune disorders. PMID:25593280

  6. [Investigation on bovine leukocyte adhesion deficiency].

    PubMed

    Ma, Jin-Zhu; Cui, Yu-Dong; Zhu, Zhan-Bo; Cao, Hong-Wei; Piao, Fan-Ze

    2006-10-01

    Bovine leukocyte adhesion deficiency (BLAD) is autosomal recessive disease. The pathogeny of BLAD is genic mutation of CD18-integrins on the leukocyte. In order to know the carrier and occurrence of bovine leukocyte adhesion deficiency (BLAD) among cows age from one to six years old in China, 1,000 cows were investigated by means of amplifying a CD18 gene fragment via reverse transcriptase-PCR followed by restriction digestion with Taq I. Results showed that 19 cows were BLAD carriers, indicating that the BLAD carrier rate was 1.9 percent. In addition, one cow was found to have BLAD. PMID:17035180

  7. Leukocyte Activation in Obese Patients

    PubMed Central

    Minervino, Daniele; Gumiero, Daniela; Nicolazzi, Maria Anna; Carnicelli, Annamaria; Fuorlo, Mariella; Guidone, Caterina; Di Gennaro, Leonardo; Fattorossi, Andrea; Mingrone, Geltrude; Landolfi, Raffaele

    2015-01-01

    Abstract The rising prevalence of obesity is a major global health problem. In severe obesity, bariatric surgery (BS) allows to obtain a significant weight loss and comorbidities improvement, among them one of the factors is the thrombotic risk. In this observational study, we measured indices of leukocyte activation in severely obese patients as markers of increased thrombotic risk in relation with serum markers of inflammation before and after BS. Frequency of polymorphonuclear neutrophil-platelet (PLT) and monocyte (MONO)-PLT aggregates as well as of tissue factor (TF) expressing MONOs was measured in the peripheral blood of 58 consecutive obese patients and 30 healthy controls. In 31 of the 58 obese patients, data obtained at the enrollment were compared with those obtained at 3, 6, and 12 months after BS. Compared with healthy controls, obese patients showed a higher frequency of polymorphonuclear leukocyte (PMNL)-PLT aggregates (7.47 ± 2.45 [6.82–8.11]% vs 5.85 ± 1.89 [5.14–6.55]%, P = 0.001), MONO-PLT aggregates (12.31 ± 7.33 [10.38–14.24]% vs 8.14 ± 2.22 [7.31–8.97]%, P < 0.001), and TF expressing MONOs (4.01 ± 2.11 [3.45–4.56]% vs 2.64 ± 1.65 [2.02–3.25]%, P = 0.002). PMNL-PLT and MONO-PLT aggregate frequency was positively correlated with TF expressing MONOs (R2 = 0.260, P = 0.049 and R2 = 0.318, P = 0.015, respectively). BS was performed in 31 patients and induced a significant reduction of the body mass index, and waist and hip circumferences. These effects were associated with a significant decrease of PMNL-PLT aggregates at 12 months (7.58 ± 2.27 [6.75–8.42]% vs 4.47 ± 1.11 [3.93–5.01]%, P < 0.001), and a reduction of TF expressing MONOs at 6 (3.82 ± 2.04 [3.07–4.57]% vs 1.60 ± 1.69 [0.30–2.90]%, P = 0.008) and 12 months (3.82 ± 2.04 [3.07–4.57]% vs 1.71 ± 0.54 [1.45–1.97]%, P = 0.001) after BS. These data suggest that leukocyte

  8. Comparison of In-111-MERC leukocytes with In-111-Oxine leukocytes for abscess detection

    SciTech Connect

    Intenzo, C.M.; Desai, A.G.; Thakur, M.L.; Park, C.H.

    1985-05-01

    This study was done to compare the clinical results of generally accepted Indium-111-oxine (oxine) labeled leukocytes with a relatively newer Indium-111-2-Mercaptopyridine-N-oxide (Merc) labeled leukocytes for the detection of occult abscesses. Of the 74 patients suspected of harboring an occult abscess, autologous leukocytes of 34 patients were labeled with oxine while in 40 patients Merc labeled leukocytes were used. Whole body imaging was performed at 24 hours. Interpretation of the scans was done without the knowledge of the leukocyte label (i.e. oxine vs Merc). The diagnosis was confirmed in each case by either subsequent clinical course, radiographic correlation (CT, US, etc.), surgery pathology, or autopsy. The results presented in this paper indicate that there is no significant difference between the Merc and oxine labeled leukocytes for abscess detection. The ease of labeling and potential availability of Merc as a kit is an advantage.

  9. Fc fusion as a platform technology: potential for modulating immunogenicity.

    PubMed

    Levin, Ditza; Golding, Basil; Strome, Scott E; Sauna, Zuben E

    2015-01-01

    The platform technology of fragment crystallizable (Fc) fusion, in which the Fc region of an antibody is genetically linked to an active protein drug, is among the most successful of a new generation of bioengineering strategies. Immunogenicity is a critical safety concern in the development of any protein therapeutic. While the therapeutic goal of generating Fc-fusion proteins has been to extend half-life, there is a critical mass of literature from immunology indicating that appropriate design of the Fc component has the potential to engage the immune system for product-specific outcomes. In the context of Fc-fusion therapeutics, a review of progress in understanding Fc biology suggests the prospect of engineering products that have an extended half-life and are able to modulate the immune system.

  10. Harnessing Fc receptor biology in the design of therapeutic antibodies.

    PubMed

    Sondermann, Peter; Szymkowski, David E

    2016-06-01

    The antibody Fc domain engages the small family of Fc receptors, expressed on cells of the immune system and beyond, to stimulate a rich diversity of positive and negative cell-mediated effector functions. The emergence of monoclonal antibodies for the treatment of various pathologic conditions has provided additional insights into Fc receptor biology, and has suggested new strategies to exploit Fc receptor interactions to create improved therapeutics. While most therapeutic IgGs approved to date have retained a native IgG Fc domain, the knowledge gained over the last decades has provided the opportunity to design tailored and more efficacious immunotherapies exhibiting fewer side effects and longer half-life. This review summarizes recent advances made in the design of biologics that modulate or exploit Fc receptor-IgG interactions, and describes innovative drugs currently under investigation in clinical trials that have been precisely tuned to achieve a desired therapeutic effect. PMID:27038127

  11. Fc fusion as a platform technology: potential for modulating immunogenicity.

    PubMed

    Levin, Ditza; Golding, Basil; Strome, Scott E; Sauna, Zuben E

    2015-01-01

    The platform technology of fragment crystallizable (Fc) fusion, in which the Fc region of an antibody is genetically linked to an active protein drug, is among the most successful of a new generation of bioengineering strategies. Immunogenicity is a critical safety concern in the development of any protein therapeutic. While the therapeutic goal of generating Fc-fusion proteins has been to extend half-life, there is a critical mass of literature from immunology indicating that appropriate design of the Fc component has the potential to engage the immune system for product-specific outcomes. In the context of Fc-fusion therapeutics, a review of progress in understanding Fc biology suggests the prospect of engineering products that have an extended half-life and are able to modulate the immune system. PMID:25488117

  12. FC vehicle hybridisation: an affordable solution for an energy-efficient FC powered drive train

    NASA Astrophysics Data System (ADS)

    Pede, G.; Iacobazzi, A.; Passerini, S.; Bobbio, A.; Botto, G.

    Fuel cells (FCs) have potential as clean and efficient energy sources for automotive applications without sacrifice in performance or driving range. However, the complete FC system must operate as efficiently as possible over the range of driving conditions that may be encountered while maintaining a low cost. To achieve this target, a storage unit can be introduced in the FC system to reduce the size of the fuel cell that is the most expensive component. This "hybrid" concept would not only reduce the drive train total cost but it also allow the recover of the braking energy and the operation at the voltage-current point of maximum efficiency for the FC system. Pro-and-cons of the "full-power" versus the "hybrid" configuration are shown in this work. The "Hybridisation rate" or "Hybridisation degree", a parameter expressed by the relationship between two installed powers, the generation power and the traction power, is also introduced and it is demonstrated that for each category of hybrid vehicles there is an optimal value of hybridisation degree. The storage systems considered are based on high power batteries or ultra capacitors (UCs) or a combination of them. A preliminary design of a sport utility vehicle (SUV) using a combined storage system and a FC energy source (called Triple Hybrid), is proposed. Finally, the experience of the Italian industry in this field is also reviewed.

  13. Metabolomics profiling reveals novel markers for leukocyte telomere length

    PubMed Central

    Zierer, Jonas; Kastenmüller, Gabi; Suhre, Karsten; Gieger, Christian; Codd, Veryan; Tsai, Pei-Chien; Bell, Jordana; Peters, Annette; Strauch, Konstantin; Schulz, Holger; Weidinger, Stephan; Mohney, Robert P.; Samani, Nilesh J.; Spector, Tim; Mangino, Massimo; Menni, Cristina

    2016-01-01

    Leukocyte telomere length (LTL) is considered one of the most predictive markers of biological aging. The aim of this study was to identify novel pathways regulating LTL using a metabolomics approach. To this end, we tested associations between 280 blood metabolites and LTL in 3511 females from TwinsUK and replicated our results in the KORA cohort. We furthermore tested significant metabolites for associations with several aging-related phenotypes, gene expression markers and epigenetic markers to investigate potential underlying pathways. Five metabolites were associated with LTL: Two lysolipids, 1-stearoylglycerophosphoinositol (P=1.6×10−5) and 1-palmitoylglycerophosphoinositol (P=1.6×10−5), were found to be negatively associated with LTL and positively associated with phospholipase A2 expression levels suggesting an involvement of fatty acid metabolism and particularly membrane composition in biological aging. Moreover, two gamma-glutamyl amino acids, gamma-glutamyltyrosine (P=2.5×10−6) and gamma-glutamylphenylalanine (P=1.7×10−5), were negatively correlated with LTL. Both are products of the glutathione cycle and markers for increased oxidative stress. Metabolites were also correlated with functional measures of aging, i.e. higher blood pressure and HDL cholesterol levels and poorer lung, liver and kidney function. Our results suggest an involvement of altered fatty acid metabolism and increased oxidative stress in human biological aging, reflected by LTL and age-related phenotypes of vital organ systems. PMID:26797767

  14. In Vivo Mechanisms Involved in Enhanced Protection Utilizing an Fc Receptor-Targeted Mucosal Vaccine Platform in a Bacterial Vaccine and Challenge Model

    PubMed Central

    Babadjanova, Zulfia; Gosselin, Edmund J.

    2014-01-01

    Targeting antigens (Ag) to Fcγ receptors (FcγR) intranasally (i.n.) enhances immunogenicity and protection against intracellular and extracellular pathogens. Specifically, we have demonstrated that targeting fixed (inactivated) Francisella tularensis (iFT) organisms to FcR in mice i.n., with MAb-iFT immune complexes, enhances F. tularensis-specific immune responses and protection against F. tularensis challenge. Furthermore, traditional adjuvant is not required. In addition, we have demonstrated that the increased immunogenicity following the targeting of iFT to FcR is due, in part, to enhanced dendritic cell (DC) maturation, enhanced internalization, and processing and presentation of iFT by DCs, as well as neonatal FcR (FcRn)-enhanced trafficking of iFT from the nasal passage to the nasal mucosa-associated lymphoid tissue (NALT). Using this immunization and challenge model, we expanded on these studies to identify specific in vivo immune responses impacted and enhanced by FcR targeting of iFT i.n. Specifically, the results of this study demonstrate for the first time that targeting iFT to FcR increases the frequency of activated DCs within the lungs of MAb-iFT-immunized mice subsequent to F. tularensis LVS challenge. In addition, the frequency and number of gamma interferon (IFN-γ)-secreting effector memory (EM) CD4+ T cells elicited by F. tularensis infection (postimmunization) is increased in an interleukin 12 (IL-12)-dependent manner. In summary, these studies build significantly upon previously published work utilizing this vaccine platform. We have identified a number of additional mechanisms by which this novel, adjuvant-independent, FcR-targeted mucosal vaccine approach enhances immunity and protection against infection, while further validating its potential as a universal vaccine platform against mucosal pathogens. PMID:25312957

  15. Indium-111 autologous leukocyte imaging in pancreatitis

    SciTech Connect

    Anderson, J.R.; Spence, R.A.; Laird, J.D.; Ferguson, W.R.; Kennedy, T.L.

    1986-03-01

    Thirty-nine patients with acute pancreatitis have been assessed using a prognostic factor grading system, abdominal ultrasound, and autologous leukocyte imaging. Both prognostic factor grading and leukocyte imaging can accurately assess the severity of the disease early in its course. All patients with a negative indium-labeled leukocyte image recovered without sequelae, whereas five of the 12 patients with a positive image developed complications, including two deaths. Abdominal ultrasound is of no value in assessing severity, but is a useful method of detecting those patients with gallstone-associated disease. In patients with suspected abscess formation following acute pancreatitis, indium leukocyte imaging does not differentiate between fat necrosis and abscess formation. In this situation, computerized tomography should be carried out before laparotomy is undertaken.

  16. Leukocyte filtration in lung transplantation.

    PubMed

    Kurusz, Mark; Roach, John D; Vertrees, Roger A; Girouard, Mark K; Lick, Scott D

    2002-05-01

    Controlled reperfusion of the transplanted lung has been used in nine consecutive patients to decrease manifestations of lung reperfusion injury. An extracorporeal circuit containing a roller pump, heat exchanger and leukodepleting filter is primed with substrate-enhanced reperfusion solution mixed with approximately 2000 ml of the patient's blood. This solution is slowly recirculated to remove leukocytes prior to reperfusion. When the pulmonary anastomoses are completed, the pulmonary artery is cannulated through the untied anastomosis using a catheter containing a pressure lumen for measurement of infusion pressure. An atrial clamp is left in place on the patient's native atrial cuff to decrease the risk of systemic air embolism during the brief period of reperfusion from the extracorporeal reservoir. During reperfusion, the water bath to the heat exchanger is kept at 35 degrees C and the flow rate for reperfusion solution is between 150 and 200 m/min, keeping the pulmonary artery pressure <14 mmHg. Eight of nine patients were ventilated on 40% inspired oxygen within a few hours of operation and 7/9 were extubated on or before postoperative day 1. Six of nine patients are long-term survivors.

  17. Leukocyte filtration in lung transplantation.

    PubMed

    Kurusz, Mark; Roach, John D; Vertrees, Roger A; Girouard, Mark K; Lick, Scott D

    2002-05-01

    Controlled reperfusion of the transplanted lung has been used in nine consecutive patients to decrease manifestations of lung reperfusion injury. An extracorporeal circuit containing a roller pump, heat exchanger and leukodepleting filter is primed with substrate-enhanced reperfusion solution mixed with approximately 2000 ml of the patient's blood. This solution is slowly recirculated to remove leukocytes prior to reperfusion. When the pulmonary anastomoses are completed, the pulmonary artery is cannulated through the untied anastomosis using a catheter containing a pressure lumen for measurement of infusion pressure. An atrial clamp is left in place on the patient's native atrial cuff to decrease the risk of systemic air embolism during the brief period of reperfusion from the extracorporeal reservoir. During reperfusion, the water bath to the heat exchanger is kept at 35 degrees C and the flow rate for reperfusion solution is between 150 and 200 m/min, keeping the pulmonary artery pressure <14 mmHg. Eight of nine patients were ventilated on 40% inspired oxygen within a few hours of operation and 7/9 were extubated on or before postoperative day 1. Six of nine patients are long-term survivors. PMID:12009087

  18. The multiple faces of leukocyte interstitial migration

    PubMed Central

    Lämmermann, Tim; Germain, Ronald N.

    2014-01-01

    Spatiotemporal control of leukocyte dynamics within tissues is critical for successful innate and adaptive immune responses. Homeostatic trafficking and coordinated infiltration into and within sites of inflammation and infection rely on signaling in response to extracellular cues that in turn controls a variety of intracellular protein networks regulating leukocyte motility, migration, chemotaxis, positioning, and cell–cell interaction. In contrast to mesenchymal cells, leukocytes migrate in an amoeboid fashion by rapid cycles of actin polymerization and actomyosin contraction, and their migration in tissues is generally referred to as low adhesive and nonproteolytic. The interplay of actin network expansion, contraction, and adhesion shapes the exact mode of amoeboid migration, and in this review, we explore how leukocyte subsets potentially harness the same basic biomechanical mechanisms in a cell-type-specific manner. Most of our detailed understanding of these processes derives from in vitro migration studies in three-dimensional gels and confined spaces that mimic geometrical aspects of physiological tissues. We summarize these in vitro results and then critically compare them to data from intravital imaging of leukocyte interstitial migration in mouse tissues. We outline the technical challenges of obtaining conclusive mechanistic results from intravital studies, discuss leukocyte migration strategies in vivo, and present examples of mode switching during physiological interstitial migration. These findings are also placed in the context of leukocyte migration defects in primary immunodeficiencies. This overview of both in vitro and in vivo studies highlights recent progress in understanding the molecular and biophysical mechanisms that shape robust leukocyte migration responses in physiologically complex and heterogeneous environments. PMID:24573488

  19. Human antibody-Fc receptor interactions illuminated by crystal structures.

    PubMed

    Woof, Jenny M; Burton, Dennis R

    2004-02-01

    Immunoglobulins couple the recognition of invading pathogens with the triggering of potent effector mechanisms for pathogen elimination. Different immunoglobulin classes trigger different effector mechanisms through interaction of immunoglobulin Fc regions with specific Fc receptors (FcRs) on immune cells. Here, we review the structural information that is emerging on three human immunoglobulin classes and their FcRs. New insights are provided, including an understanding of the antibody conformational adjustments that are required to bring effector cell and target cell membranes sufficiently close for efficient killing and signal transduction to occur. The results might also open up new possibilities for the design of therapeutic antibodies.

  20. Dual role for Fcγ receptors in host defense and disease in Borrelia burgdorferi-infected mice

    PubMed Central

    Belperron, Alexia A.; Liu, Nengyin; Booth, Carmen J.; Bockenstedt, Linda K.

    2014-01-01

    Arthritis in mice infected with the Lyme disease spirochete, Borrelia burgdorferi, results from the influx of innate immune cells responding to the pathogen in the joint and is influenced in part by mouse genetics. Production of inflammatory cytokines by innate immune cells in vitro is largely mediated by Toll-like receptor (TLR) interaction with Borrelia lipoproteins, yet surprisingly mice deficient in TLR2 or the TLR signaling molecule MyD88 still develop arthritis comparable to that seen in wild type mice after B. burgdorferi infection. These findings suggest that other, MyD88-independent inflammatory pathways can contribute to arthritis expression. Clearance of B. burgdorferi is dependent on the production of specific antibody and phagocytosis of the organism. As Fc receptors (FcγR) are important for IgG-mediated clearance of immune complexes and opsonized particles by phagocytes, we examined the role that FcγR play in host defense and disease in B. burgdorferi-infected mice. B. burgdorferi-infected mice deficient in the Fc receptor common gamma chain (FcεRγ−/− mice) harbored ~10 fold more spirochetes than similarly infected wild type mice, and this was associated with a transient increase in arthritis severity. While the elevated pathogen burdens seen in B. burgdorferi-infected MyD88−/− mice were not affected by concomitant deficiency in FcγR, arthritis was reduced in FcεRγ−/−MyD88−/− mice in comparison to wild type or single knockout mice. Gene expression analysis from infected joints demonstrated that absence of both MyD88 and FcγR lowers mRNA levels of proteins involved in inflammation, including Cxcl1 (KC), Xcr1 (Gpr5), IL-1beta, and C reactive protein. Taken together, our results demonstrate a role for FcγR-mediated immunity in limiting pathogen burden and arthritis in mice during the acute phase of B. burgdorferi infection, and further suggest that this pathway contributes to the arthritis that develops in B. burgdorferi

  1. Leukocyte chemoattractant activity of diacylglycerol

    SciTech Connect

    Wright, T.M.; Hoffman, R.D.; Nishijima, J.; Shin, H.S.

    1986-03-05

    Phosphatidylinositol breakdown with the generation of 1,2-diacylglycerol (1,2-DG) and inositol phosphates occurs in response to receptor mediated stimulation of lymphocytes and polymorphonuclear neutrophils (PMN). In the authors attempt to demonstrate the direct role of 1,2-DG in cell migration, they have found 1,2 dioctanoyl glycerol (1,2-C8DG) to be a chemoattractant for 6C3HED, a mouse thymic lymphoma, and human peripheral blood PMN's. The chemoattractant activity for both cell types was observed at concentrations from 0.5 to 10mM in an under agarose assay. The maximum effect of 1,2-C8DG on 6C3HED cells was similar to that of 1mM lysophosphatidylcholine and the maximum effect of 1,2-C8DG on PMN's was similar to that of 10/sup -7/M f-met-leu-phe. Other 1,2-DG's with acyl chains ranging from 6 to 18 carbons in length and 1-oleoyl-2-acetyl-glycerol were also chemoattractants for 6C3HED, although their activities were less than 1,2-C8DG. In addition, phorbol myristate acetate (PMA), another activator of protein kinase C, was a chemoattractant for 6C3HED and human PMN's. PMA was more potent than 1,2-C8DG for both 6C3HED and PMN's with chemoattractant activity in the range of 30nM to 1..mu..M. These studies support the direct role of 1,2-DG in the transduction of chemotactic stimuli in leukocytes and further suggest that the formation of diacylglycerol represents a common step in the migratory responses of lymphoid and myeloid cells.

  2. Leukocyte Recruitment and Ischemic Brain Injury

    PubMed Central

    Yilmaz, Gokhan

    2010-01-01

    Leukocytes are recruited into the cerebral microcirculation following an ischemic insult. The leukocyte–endothelial cell adhesion manifested within a few hours after ischemia (followed by reperfusion, I/R) largely reflects an infiltration of neutrophils, while other leukocyte populations appear to dominate the adhesive interactions with the vessel wall at 24 h of reperfusion. The influx of rolling and adherent leukocytes is accompanied by the recruitment of adherent platelets, which likely enhances the cytotoxic potential of the leukocytes to which they are attached. The recruitment of leukocytes and platelets in the postischemic brain is mediated by specific adhesion glycoproteins expressed by the activated blood cells and on cerebral microvascular endothelial cells. This process is also modulated by different signaling pathways (e.g., CD40/CD40L, Notch) and cytokines (e.g., RANTES) that are activated/released following I/R. Some of the known risk factors for cardiovascular disease, including hypercholesterolemia and obesity appear to exacerbate the leukocyte and platelet recruitment elicited by brain I/R. Although lymphocyte–endothelial cell and –platelet interactions in the postischemic cerebral microcirculation have not been evaluated to date, recent evidence in experimental animals implicate both CD4+ and CD8+ T-lymphocytes in the cerebral microvascular dysfunction, inflammation, and tissue injury associated with brain I/R. Evidence implicating regulatory T-cells as cerebroprotective modulators of the inflammatory and tissue injury responses to brain I/R support a continued focus on leukocytes as a target for therapeutic intervention in ischemic stroke. PMID:19579016

  3. Acoustic nonlinearity in fluorinert FC-43

    SciTech Connect

    Pantea, Cristian; Sinha, Dipen N; Osterhoudt, Curtis F; Mombourquette, Paul C

    2009-01-01

    Fluorinert FC-43 nonlinearity was investigated using two approaches: (i) a finite amplitude method with harmonic production; and (ii) a nonlinear frequency mixing in the fluid with consequent beam profile measurement of the difference frequency. The finite amplitude method provides information on the coefficient of nonlinearity, {beta}, through the amplitudes of the fundamental and the second harmonic, at a certain transmitter-receiver distance. A calibrated hydrophone was used as a receiver, in order to obtain direct pressure measurements of the acoustic waves in the fluid. The role of transmitter-receiver distance in {beta} determination is investigated. In the second approach, a single transducer is used to provide two high-frequency beams. The collinear high-frequency beams mix nonlinearly in the fluid resulting in a difference frequency beam and higher order harmonics of the primaries. The difference frequency beam profite is investigated at lengths beyond the mixing distance. The experimental data are compured with the KZK theory.

  4. Polymeric human Fc-fusion proteins with modified effector functions

    NASA Astrophysics Data System (ADS)

    Mekhaiel, David N. A.; Czajkowsky, Daniel M.; Andersen, Jan Terje; Shi, Jianguo; El-Faham, Marwa; Doenhoff, Michael; McIntosh, Richard S.; Sandlie, Inger; He, Jianfeng; Hu, Jun; Shao, Zhifeng; Pleass, Richard J.

    2011-10-01

    The success of Fc-fusion bio-therapeutics has spurred the development of other Fc-fusion products for treating and/or vaccinating against a range of diseases. We describe a method to modulate their function by converting them into well-defined stable polymers. This strategy resulted in cylindrical hexameric structures revealed by tapping mode atomic force microscopy (AFM). Polymeric Fc-fusions were significantly less immunogenic than their dimeric or monomeric counterparts, a result partly owing to their reduced ability to interact with critical Fc-receptors. However, in the absence of the fusion partner, polymeric IgG1-Fc molecules were capable of binding selectively to FcγRs, with significantly increased affinity owing to their increased valency, suggesting that these reagents may prove of immediate utility in the development of well-defined replacements for intravenous immunoglobulin (IVIG) therapy. Overall, these findings establish an effective IgG Fc-fusion based polymeric platform with which the therapeutic and vaccination applications of Fc-fusion immune-complexes can now be explored.

  5. Enhancing Antibody Fc Heterodimer Formation through Electrostatic Steering Effects

    PubMed Central

    Gunasekaran, Kannan; Pentony, Martin; Shen, Min; Garrett, Logan; Forte, Carla; Woodward, Anne; Ng, Soo Bin; Born, Teresa; Retter, Marc; Manchulenko, Kathy; Sweet, Heather; Foltz, Ian N.; Wittekind, Michael; Yan, Wei

    2010-01-01

    Naturally occurring IgG antibodies are bivalent and monospecific. Bispecific antibodies having binding specificities for two different antigens can be produced using recombinant technologies and are projected to have broad clinical applications. However, co-expression of multiple light and heavy chains often leads to contaminants and pose purification challenges. In this work, we have modified the CH3 domain interface of the antibody Fc region with selected mutations so that the engineered Fc proteins preferentially form heterodimers. These novel mutations create altered charge polarity across the Fc dimer interface such that coexpression of electrostatically matched Fc chains support favorable attractive interactions thereby promoting desired Fc heterodimer formation, whereas unfavorable repulsive charge interactions suppress unwanted Fc homodimer formation. This new Fc heterodimer format was used to produce bispecific single chain antibody fusions and monovalent IgGs with minimal homodimer contaminants. The strategy proposed here demonstrates the feasibility of robust production of novel Fc-based heterodimeric molecules and hence broadens the scope of bispecific molecules for therapeutic applications. PMID:20400508

  6. Antibody-Fc receptor interactions in protection against intracellular pathogens.

    PubMed

    Joller, Nicole; Weber, Stefan S; Oxenius, Annette

    2011-04-01

    Intracellular pathogen-specific antibodies (Abs) can contribute to host protection by a number of different mechanisms. Ab opsonization of pathogens residing outside a host cell can prevent infection of target cells either via neutralization of the critical surface epitopes required for host cell entry, complement-mediated degradation, or via subsequent intracellular degradation. In the case of intracellular localization, Abs can bind to infected cells and thus mark them for destruction by Fc receptor (FcR)-bearing effector cells. This review focuses on the protective role of Abs against intracellular bacteria and parasites involving FcR interactions that modulate the intracellular trafficking of the pathogen, the ability of FcRs to interfere with the establishment of an intracellular replicative niche and the involvement of FcRs to modulate pathogen-specific T-cell responses. PMID:21413006

  7. Fc glycans of therapeutic antibodies as critical quality attributes

    PubMed Central

    Reusch, Dietmar; Tejada, Max L

    2015-01-01

    Critical quality attributes (CQA) are physical, chemical, biological or microbiological properties or characteristics that must be within an appropriate limit, range or distribution to ensure the desired product quality, safety and efficacy. For monoclonal antibody therapeutics that rely on fraction crystalizable (Fc)-mediated effector function for their clinical activity, the terminal sugars of Fc glycans have been shown to be critical for safety or efficacy. Different glycosylation variants have also been shown to influence the pharmacodynamic and pharmacokinetic behavior while other Fc glycan structural elements may be involved in adverse immune reactions. This review focuses on the role of Fc glycans as CQAs. Fc glycan information from the published literature is summarized and evaluated for impact on patient safety, immunogenicity, bioactivity and pharmacodynamics/pharmacokinetics. PMID:26263923

  8. Antibody-Fc receptor interactions in protection against intracellular pathogens.

    PubMed

    Joller, Nicole; Weber, Stefan S; Oxenius, Annette

    2011-04-01

    Intracellular pathogen-specific antibodies (Abs) can contribute to host protection by a number of different mechanisms. Ab opsonization of pathogens residing outside a host cell can prevent infection of target cells either via neutralization of the critical surface epitopes required for host cell entry, complement-mediated degradation, or via subsequent intracellular degradation. In the case of intracellular localization, Abs can bind to infected cells and thus mark them for destruction by Fc receptor (FcR)-bearing effector cells. This review focuses on the protective role of Abs against intracellular bacteria and parasites involving FcR interactions that modulate the intracellular trafficking of the pathogen, the ability of FcRs to interfere with the establishment of an intracellular replicative niche and the involvement of FcRs to modulate pathogen-specific T-cell responses.

  9. Engineered antibody Fc variants with enhanced effector function

    NASA Astrophysics Data System (ADS)

    Lazar, Greg A.; Dang, Wei; Karki, Sher; Vafa, Omid; Peng, Judy S.; Hyun, Linus; Chan, Cheryl; Chung, Helen S.; Eivazi, Araz; Yoder, Sean C.; Vielmetter, Jost; Carmichael, David F.; Hayes, Robert J.; Dahiyat, Bassil I.

    2006-03-01

    Antibody-dependent cell-mediated cytotoxicity, a key effector function for the clinical efficacy of monoclonal antibodies, is mediated primarily through a set of closely related Fc receptors with both activating and inhibitory activities. By using computational design algorithms and high-throughput screening, we have engineered a series of Fc variants with optimized Fc receptor affinity and specificity. The designed variants display >2 orders of magnitude enhancement of in vitro effector function, enable efficacy against cells expressing low levels of target antigen, and result in increased cytotoxicity in an in vivo preclinical model. Our engineered Fc regions offer a means for improving the next generation of therapeutic antibodies and have the potential to broaden the diversity of antigens that can be targeted for antibody-based tumor therapy. antibody-dependent cell-mediated cytotoxicity | FcR | protein engineering | cancer

  10. Halloysite Nanotube Coatings Suppress Leukocyte Spreading.

    PubMed

    Hughes, Andrew D; Marsh, Graham; Waugh, Richard E; Foster, David G; King, Michael R

    2015-12-22

    The nanoscale topography of adhesive surfaces is known to be an important factor governing cellular behavior. Previous work has shown that surface coatings composed of halloysite nanotubes enhance the adhesion, and therefore capture of, rare target cells such as circulating tumor cells. Here we demonstrate a unique feature of these coatings in their ability to reduce the adhesion of leukocytes and prevent leukocyte spreading. Surfaces were prepared with coatings of halloysite nanotubes and functionalized for leukocyte adhesion with E-selectin, and the dilution of nanotube concentration revealed a threshold concentration below which cell spreading became comparable to smooth surfaces. Evaluation of surface roughness characteristics determined that the average distance between discrete surface features correlated with adhesion metrics, with a separation distance of ∼2 μm identified as the critical threshold. Computational modeling of the interaction of leukocytes with halloysite nanotube-coated surfaces of varying concentrations demonstrates that the geometry of the cell surface and adhesive counter-surface produces a significantly diminished effective contact area compared to a leukocyte interacting with a smooth surface.

  11. Crucial role for the LSP1-myosin1e bimolecular complex in the regulation of Fcγ receptor-driven phagocytosis.

    PubMed

    Maxeiner, Sebastian; Shi, Nian; Schalla, Carmen; Aydin, Guelcan; Hoss, Mareike; Vogel, Simon; Zenke, Martin; Sechi, Antonio S

    2015-05-01

    Actin cytoskeleton remodeling is fundamental for Fcγ receptor-driven phagocytosis. In this study, we find that the leukocyte-specific protein 1 (LSP1) localizes to nascent phagocytic cups during Fcγ receptor-mediated phagocytosis, where it displays the same spatial and temporal distribution as the actin cytoskeleton. Down-regulation of LSP1 severely reduces the phagocytic activity of macrophages, clearly demonstrating a crucial role for this protein in Fcγ receptor-mediated phagocytosis. We also find that LSP1 binds to the class I molecular motor myosin1e. LSP1 interacts with the SH3 domain of myosin1e, and the localization and dynamics of both proteins in nascent phagocytic cups mirror those of actin. Furthermore, inhibition of LSP1-myosin1e and LSP1-actin interactions profoundly impairs pseudopodial formation around opsonized targets and their subsequent internalization. Thus the LSP1-myosin1e bimolecular complex plays a pivotal role in the regulation of actin cytoskeleton remodeling during Fcγ receptor-driven phagocytosis.

  12. Leukocytes Crossing the Endothelium: A Matter of Communication.

    PubMed

    Timmerman, Ilse; Daniel, Anna E; Kroon, Jeffrey; van Buul, Jaap D

    2016-01-01

    Leukocytes cross the endothelial vessel wall in a process called transendothelial migration (TEM). The purpose of leukocyte TEM is to clear the causing agents of inflammation in underlying tissues, for example, bacteria and viruses. During TEM, endothelial cells initiate signals that attract and guide leukocytes to sites of tissue damage. Leukocytes react by attaching to these sites and signal their readiness to move back to endothelial cells. Endothelial cells in turn respond by facilitating the passage of leukocytes while retaining overall integrity. In this review, we present recent findings in the field and we have endeavored to synthesize a coherent picture of the intricate interplay between endothelial cells and leukocytes during TEM.

  13. Characterization of the ligand binding site of the bovine IgA Fc receptor (bFc alpha R).

    PubMed

    Morton, H Craig; Pleass, Richard J; Woof, Jenny M; Brandtzaeg, Per

    2004-12-24

    Recently, we identified a bovine IgA Fc receptor (bFc alpha R), which shows high homology to the human myeloid Fc alpha R, CD89. IgA binding has previously been shown to depend on several specific residues located in the B-C and F-G loops of the membrane-distal extracellular domain 1 of CD89. To compare the ligand binding properties of these two Fc alpha Rs, we have mapped the IgA binding site of bFc alpha R. We show that, in common with CD89, Tyr-35 in the B-C loop is essential for IgA binding. However, in contrast to earlier observations on CD89, mutation of residues in the F-G loop did not significantly inhibit IgA binding.

  14. Osteomyelitis: diagnosis with In-111-labeled leukocytes

    SciTech Connect

    Schauwecker, D.S.

    1989-04-01

    In a retrospective review, 485 patients with suspected osteomyelitis were studied. Of these, 453 patients were studied with both bone and indium-111 leukocyte scanning (173 sequentially and 280 simultaneously). The ability to determine that the infection was in bone rather than in adjacent soft tissue was greater with simultaneous bone scan and In-111 leukocyte studies than with sequential studies. The locations of suspected osteomyelitis were divided into central (containing active bone marrow), peripheral (hands and feet), and middle (between central and peripheral). Specificity remained high (about 90%) regardless of the location. Overall sensitivity was significantly lower in the central location than in the peripheral or middle location. Determination of whether the In-111 leukocyte activity was in bone or adjacent soft tissue was also more difficult when the infection was in the central location. For acute osteomyelitis, sensitivity was high regardless of the location. For chronic osteomyelitis, sensitivity was lower in the central location.

  15. Intravascular leukocyte migration through platelet thrombi: directing leukocytes to sites of vascular injury.

    PubMed

    Ghasemzadeh, Mehran; Hosseini, Ehteramolsadat

    2015-06-01

    Leukocytes recruitment to thrombi supports an intimate cellular interaction leading to the enhancement of pro-coagulant functions and pro-inflammatory responses at site of vascular injury. Recent observations of neutrophil extracellular traps (NETs) formation and its mutual reactions with platelet thrombi adds more clinical interest to the growing body of knowledge in the field of platelet-leukocyte cross-talk. However, having considered thrombus as a barrier between leukocytes and injured endothelium, the full inflammatory roles of these cells during thrombosis is still ill defined. The most recent observation of neutrophils migration into the thrombi is a phenomenon that highlights the inflammatory functions of leukocytes at the site of injury. It has been hypothesised that leukocytes migration might be associated with the conveyance of highly reactive pro-inflammatory and/or pro-coagulant mediators to sites of vascular injury. In addition, the evidence of neutrophils migration into arterial thrombi following traumatic and ischaemia-reperfusion injury highlights the already described role of these cells in atherosclerosis. Regardless of the mechanisms behind leukocyte migration, whether these migrated cells benefit normal homeostasis by their involvement in wound healing and vascular rebuilding or they increase unwilling inflammatory responses, could be of interest for future researches that provide new insight into biological importance of leukocyte recruitment to thrombi.

  16. Computational modeling of the Fc αRI receptor binding in the Fc α domain of the human antibody IgA: Normal Modes Analysis (NMA) study

    NASA Astrophysics Data System (ADS)

    Jayasinghe, Manori; Posgai, Monica; Tonddast-Navaei, Sam; Ibrahim, George; Stan, George; Herr, Andrew; George Stan Group Collaboration; Herr's Group Team

    2014-03-01

    Fc αRI receptor binding in the Fc α domain of the antibody IgA triggers immune effector responses such as phagocytosis and antibody-dependent cell-mediated cytotoxicity in eukaryotic cells. Fc α is a dimer of heavy chains of the IgA antibody and each Fc α heavy chain which consisted of two immunoglobulin constant domains, CH2 and CH3, can bind one Fc αRI molecule at the CH2-CH3 interface forming a 2:1 stoichiometry. Experimental evidences confirmed that Fc αRI binding to the Fc α CH2-CH3 junction altered the kinetics of HAA lectin binding at the distant IgA1 hinge. Our focus in this research was to understand the conformational changes and the network of residues which co-ordinate the receptor binding dynamics of the Fc α dimer complex. Structure-based elastic network modeling was used to compute normal modes of distinct Fc α configurations. Asymmetric and un-liganded Fc α configurations were obtained from the high resolution crystal structure of Fc α-Fc αRI 2:1 symmetric complex of PDB ID 1OW0. Our findings confirmed that Fc αRI binding, either in asymmetric or symmetric complex with Fc α, propagated long-range conformational changes across the Fc domains, potentially also impacting the distant IgA1 hinge.

  17. HAL/S-FC compiler system functional specification

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The functional requirements to be met by the HAL/S-FC compiler, and the hardware and software compatibilities between the compiler system and the environment in which it operates are defined. Associated runtime facilities and the interface with the Software Development Laboratory are specified. The construction of the HAL/S-FC system as functionally separate units and the interfaces between those units is described. An overview of the system's capabilities is presented and the hardware/operating system requirements are specified. The computer-dependent aspects of the HAL/S-FC are also specified. Compiler directives are included.

  18. Genetics Home Reference: leukocyte adhesion deficiency type 1

    MedlinePlus

    ... adhesion deficiency type 1 leukocyte adhesion deficiency type 1 Enable Javascript to view the expand/collapse boxes. ... All Close All Description Leukocyte adhesion deficiency type 1 is a disorder that causes the immune system ...

  19. Halo sign on indium-111 leukocyte scan in gangrenous cholecystitis

    SciTech Connect

    Bauman, J.M.; Boykin, M.; Hartshorne, M.F.; Cawthon, M.A.; Landry, A.J.

    1986-02-01

    A 56-year-old man with a long history of Crohn's disease was evaluated by In-111 labeled leukocyte scanning. A halo of leukocyte activity was seen around the gallbladder fossa. A gangrenous gallbladder was removed at surgery.

  20. Crystal Structure of the HSV-1 Fc Receptor Bound to Fc Reveals a Mechanism for Antibody Bipolar Bridging

    SciTech Connect

    Sprague, E.R.; Wang, C.; Baker, D.; Bjorkman, P.J.; /Caltech /Howard Hughes Med. Inst.

    2007-08-08

    Herpes simplex virus type-1 expresses a heterodimeric Fc receptor, gE-gI, on the surfaces of virions and infected cells that binds the Fc region of host immunoglobulin G and is implicated in the cell-to-cell spread of virus. gE-gI binds immunoglobulin G at the basic pH of the cell surface and releases it at the acidic pH of lysosomes, consistent with a role in facilitating the degradation of antiviral antibodies. Here we identify the C-terminal domain of the gE ectodomain (CgE) as the minimal Fc-binding domain and present a 1.78-{angstrom} CgE structure. A 5-{angstrom} gE-gI/Fc crystal structure, which was independently verified by a theoretical prediction method, reveals that CgE binds Fc at the C{sub H}2-C{sub H}3 interface, the binding site for several mammalian and bacterial Fc-binding proteins. The structure identifies interface histidines that may confer pH-dependent binding and regions of CgE implicated in cell-to-cell spread of virus. The ternary organization of the gE-gI/Fc complex is compatible with antibody bipolar bridging, which can interfere with the antiviral immune response.

  1. Linkage on chromosome 3 of autoimmune diabetes and defective Fc receptor for lgG in NOD mice

    SciTech Connect

    Prins, J.B.; Todd, J.A.; Rodrigues, N.R.; Ghosh, S. ); Hogarth, P.M. ); Wicker, L.S.; Podolin, P.L.; Gaffney, E.; Peterson, L.B.; Fischer, P.A.; Sirotina, A. )

    1993-04-30

    A congenic, non-obese diabetic (NOD) mouse strain that contains a segment of chromosome 3 from the diabetes-resistant mouse strain B6.PL-Thy-1[sup a] was less susceptible to diabetes than NOD mice. A fully penetrant immunological defect also mapped to this segment, which encodes the high-affinity Fc receptor for immunoglobulin G (lgG), Fc[gamma]Rl. The NOD Fcgr1 allele, which results in a deletion of the cytoplasmic tail, caused a 73 percent reduction in the turnover of cell surface receptor-antibody complexes. The development of congenic strains and the characterization of Mendelian traits that are specific to the disease phenotype demonstrate the feasibility of dissecting the pathophysiology of complex, non-Mendelian diseases.

  2. Engineered antibody Fc variants with enhanced effector function

    PubMed Central

    Lazar, Greg A.; Dang, Wei; Karki, Sher; Vafa, Omid; Peng, Judy S.; Hyun, Linus; Chan, Cheryl; Chung, Helen S.; Eivazi, Araz; Yoder, Sean C.; Vielmetter, Jost; Carmichael, David F.; Hayes, Robert J.; Dahiyat, Bassil I.

    2006-01-01

    Antibody-dependent cell-mediated cytotoxicity, a key effector function for the clinical efficacy of monoclonal antibodies, is mediated primarily through a set of closely related Fcγ receptors with both activating and inhibitory activities. By using computational design algorithms and high-throughput screening, we have engineered a series of Fc variants with optimized Fcγ receptor affinity and specificity. The designed variants display >2 orders of magnitude enhancement of in vitro effector function, enable efficacy against cells expressing low levels of target antigen, and result in increased cytotoxicity in an in vivo preclinical model. Our engineered Fc regions offer a means for improving the next generation of therapeutic antibodies and have the potential to broaden the diversity of antigens that can be targeted for antibody-based tumor therapy. PMID:16537476

  3. Bovine leukocyte adhesion deficiency: in vitro assessment of neutrophil function and leukocyte integrin expression.

    PubMed

    Olchowy, T W; Bochsler, P N; Neilsen, N R; Welborn, M G; Slauson, D O

    1994-04-01

    Bovine leukocyte adhesion deficiency (BLAD) was identified in a two-month-old Holstein heifer calf using DNA-polymerase chain reaction analysis of the affected calf and other clinical parameters. Neutrophil integrin expression (CD18, CD11a, CD11c), aggregation, and transendothelial migration were studied in vitro. Neutrophils were isolated from the affected calf and from normal, healthy, age-matched control Holstein calves. Neutrophils isolated from the affected BLAD calf had decreased expression of leukocyte integrins on their cell surface, decreased ability to aggregate in response to chemotactic stimuli, and decreased ability to migrate across bovine endothelial cell monolayers in vitro. Transendothelial migration of neutrophils from normal calves was reduced to levels comparable to the BLAD neutrophils by treatment with an anti-CD18 monoclonal antibody (MAb 60.3). Peripheral-blood lymphocytes from the BLAD calf also expressed negligible levels of leukocyte integrins, similar to their neutrophil counterparts. Our experimental findings in vitro correlate well with the clinical observations of decreased leukocyte trafficking and diminished host defense in leukocyte adhesion-deficient animals. The syndrome of BLAD may be a suitable model for one of the human leukocyte adhesion deficiency disorders. PMID:7911733

  4. Differences in leukocyte differentiation molecule abundances on domestic sheep (Ovis aries) and bighorn sheep (Ovis canadensis) neutrophils identified by flow cytometry.

    PubMed

    Highland, Margaret A; Schneider, David A; White, Stephen N; Madsen-Bouterse, Sally A; Knowles, Donald P; Davis, William C

    2016-06-01

    Although both domestic sheep (DS) and bighorn sheep (BHS) are affected by similar respiratory bacterial pathogens, experimental and field data indicate BHS are more susceptible to pneumonia. Cross-reactive monoclonal antibodies (mAbs) for use in flow cytometry (FC) are valuable reagents for interspecies comparative immune system analyses. This study describes cross-reactive mAbs that recognize leukocyte differentiation molecules (LDMs) and major histocompatibility complex antigens on DS and BHS leukocytes. Characterization of multichannel eosinophil autofluorescence in this study permitted cell-type specific gating of granulocytes for evaluating LDMs, specifically on neutrophils, by single-label FC. Evaluation of relative abundances of LDMs by flow cytometry revealed greater CD11a, CD11b, CD18 (β2 integrins) and CD 172a (SIRPα) on DS neutrophils and greater CD14 (lipopolysaccharide receptor) on BHS neutrophils. Greater CD25 (IL-2) was identified on BHS lymphocytes following Concavalin A stimulation. While DS and BHS have similar total peripheral blood leukocyte counts, BHS have proportionately more neutrophils.

  5. Pulmonary leukocytic responses are linked to the acquired immunity of mice vaccinated with irradiated cercariae of Schistosoma mansoni

    SciTech Connect

    Aitken, R.; Coulson, P.S.; Wilson, R.A.

    1988-05-15

    Pulmonary cellular responses in C57BL/6 mice exposed to Schistosoma mansoni have been investigated by sampling cells from the respiratory airways with bronchoalveolar lavage. Mice exposed to cercariae attenuated with 20 krad gamma-radiation developed stronger and more persistent pulmonary leukocytic responses than animals exposed to equal numbers of normal parasites. Although vaccination with irradiated cercariae also stimulated T cell responses of greater magnitude and duration than normal infection, the lymphocytic infiltrate elicited by each regimen did not differ substantially in its composition, 5 wk after exposure. Studies with cercariae attenuated by different treatments established that a link exists between the recruitment of leukocytes to the lungs of vaccinated mice and resistance to reinfection. There was a strong association between pulmonary leukocytic responses and the elimination of challenge infections by vaccinated mice. Animals exposed to irradiated cercariae of S. mansoni were resistant to homologous challenge infection but were not protected against Schistosoma margrebowiei. Homologous challenge of vaccinated mice stimulated anamnestic leukocytic and T lymphocytic responses in the lungs, 2 wk postinfection, but exposure of immunized animals to the heterologous species failed to trigger an expansion in these populations of cells. Our studies indicate that pulmonary leukocytes and T lymphocytes are intimately involved in the mechanism of vaccine-induced resistance to S. mansoni. It remains unclear whether these populations of cells initiate protective inflammatory reactions against challenge parasites in the lungs, or accumulate in response to the activation of the protective mechanism by other means.

  6. Adoptive immunotherapy with genetically engineered T cells: modification of the IgG1 Fc 'spacer' domain in the extracellular moiety of chimeric antigen receptors avoids 'off-target' activation and unintended initiation of an innate immune response.

    PubMed

    Hombach, A; Hombach, A A; Abken, H

    2010-10-01

    Chimeric antigen receptors (CARs, immunoreceptors) are frequently used to redirect T cells with pre-defined specificity, in particular towards tumour cells for use in adoptive immunotherapy of malignant diseases. Specific targeting is mediated by an extracellularly located antibody-derived binding domain, which is joined to the transmembrane and intracellular CD3ζ moiety for T-cell activation. Stable CAR expression in T cells, however, requires a spacer domain interposed between the binding and the transmembrane domain and which is commonly the constant IgG1 Fc domain. We here revealed that CARs with Fc spacer domain bind to IgG Fc gamma receptors (FcγRs), thereby unintentionally activating innate immune cells, including monocytes and natural killer (NK) cells, which consequently secrete high amounts of pro-inflammatory cytokines. Engineered T cells, on the other hand, are likewise activated by FcγR binding resulting in cytokine secretion and lysis of monocytes and NK cells independently of the redirected specificity. To reduce FcγR binding, we modified the spacer domain without affecting CAR expression and antigen binding. Engineered with the modified CAR, T cells are not activated in presence of FcγR(+) cells, thereby minimizing the risk of off-target activation while preserving their redirected targeting specificity.

  7. Regulation of rat basophilic leukemia-2H3 mast cell secretion by a constitutive Lyn kinase interaction with the high affinity IgE receptor (Fc epsilon RI).

    PubMed

    Vonakis, Becky M; Gibbons, Scott P; Rotté, Masashi J; Brothers, Elizabeth A; Kim, Seok C; Chichester, Kristin; MacDonald, Susan M

    2005-10-01

    Signaling through the high affinity IgE receptor is initiated by noncovalently associated Lyn kinase, resulting in the secretion of inflammatory mediators from mast cells. A fraction of the total cellular Lyn is associated via its N-terminal unique domain with the cytoplasmic domain of the Fc epsilonRI beta subunit before receptor aggregation. In the current study, we stably transfected the unique domain of Lyn into rat basophilic leukemia-2H3 mast cells and examined the consequences on Fc epsilonRI-induced signal transduction and mediator secretion to further define the role of the unique domain of Lyn in mast cell secretion. Tyrosine phosphorylation of Fc epsilonRI beta and gamma subunits was partially inhibited in the Lyn unique domain transfectants after Ag stimulation. Ag stimulation of Lyn unique domain transfectants was accompanied by enhanced phosphorylation of MEK and ERK-2, which are required for leukotriene C4 (LTC4) release, and production of LTC4 was increased 3- to 5-fold, compared with cells transfected with vector alone. Conversely, tyrosine phosphorylation of the adaptor protein Gab2, which is essential for mast cell degranulation, was inhibited after Ag stimulation of Lyn unique domain transfectants, and Ag-induced release of histamine was inhibited up to 48%. In rat basophilic leukemia-2H3 cells, Lyn thus plays a dual role by positively regulating Fc epsilonRI phosphorylation and degranulation while negatively regulating LTC4 production. This study provides further evidence that the constitutive interaction between the unique domain of Lyn and the Fc epsilonRI beta subunit is a crucial step in the initiation of Fc epsilonRI signaling and that Lyn is limiting for Fc epsilonRI-induced secretion of inflammatory mediators.

  8. Expression of soluble human Neonatal Fc-receptor (FcRn) in Escherichia coli through modification of growth environment.

    PubMed

    Ng, Woei Kean; Lim, Theam Soon; Lai, Ngit Shin

    2016-11-01

    Neonatal Fc-receptor (FcRn) with its affinity to immunoglobulin G (IgG) has been the subject of many pharmacokinetic studies in the past century. This protein is well known for its unique feature in maintaining the circulating IgG from degradation in blood plasma. FcRn is formed by non-covalent association between the α-chain with the β-2-microglobulin (β2m). Many studies have been conducted to produce FcRn in the laboratory, mainly using mammalian tissue culture as host for recombinant protein expression. In this study, we demonstrate a novel strategy to express the α-chain of FcRn using Escherichia coli as the expression host. The expression vector that carries the cDNA of the α-chain was transformed into expression host, Rosetta-gami 2 strain for inducible expression. The bacterial culture was grown in a modified growth medium which constitutes of terrific broth, sodium chloride (NaCl), glucose and betaine. A brief heat shock at 45 °C was carried out after induction, before the temperature for expression was reduced to 22 °C and grown for 16 h. The soluble form of the α-chain of FcRn expressed was tested in the ELISA and dot blot immunoassay to confirm its native functionality. The results implied that the α-chain of FcRn expressed using this method is functional and retains its pH-dependent affinity to IgG. Our study significantly suggests that the activity of human FcRn remain active and functional in the absence of β2m. PMID:27412717

  9. Differential Expression of Functional Fc-Receptors and Additional Immune Complex Receptors on Mouse Kidney Cells

    PubMed Central

    Suwanichkul, Adisak; Wenderfer, Scott E.

    2013-01-01

    The precise mechanisms by which circulating immune complexes accumulate in the kidney to form deposits in glomerulonephritis are not well understood. In particular, the role of resident cells within glomeruli of the kidney has been widely debated. Immune complexes have been shown to bind one glomerular cell type (mesangial cells) leading to functional responses such as pro-inflammatory cytokine production. To further assess the presence of functional immunoreceptors on resident glomerular cells, cultured mouse renal epithelial, endothelial, and mesangial cells were treated with heat-aggregated mouse IgG or preformed murine immune complexes. Mesangial and renal endothelial cells were found to bind IgG complexes, whereas glomerular epithelial cell binding was minimal. A blocking antibody for Fc-gamma receptors reduced binding to mesangial cells but not renal endothelial cells, suggesting differential immunoreceptor utilization. RT-PCR and immunostaining based screening of cultured renal endothelial cells showed limited low-level expression of known Fc-receptors and Igbinding proteins. The interaction between mesangial cells and renal endothelial cells and immune complexes resulted in distinct, cell-specific patterns of chemokine and cytokine production. This novel pathway involving renal endothelial cells likely contributes to the predilection of circulating immune complex accumulation within the kidney and to the inflammatory responses that drive kidney injury. PMID:23911392

  10. Therapeutic potential of inhibiting leukocyte rolling in ischemia/reperfusion.

    PubMed Central

    Kubes, P; Jutila, M; Payne, D

    1995-01-01

    Leukocyte rolling has been postulated to be mandatory for subsequent leukocyte adhesion and tissue injury observed during ischemia/reperfusion. The objective of this study was to systematically assess this hypothesis at the microvascular level by examining the effects of various concentrations of a selectin-binding carbohydrate (fucoidin) on the increased rolling and adhesion of leukocytes in postischemic venules. The contribution of L-selectin and/or P-selectin to leukocyte rolling were also assessed in this model. Using intravital microscopy we observed that 60 min of ischemia followed by reperfusion caused a profound increase in leukocyte rolling and adhesion. A high dose of fucoidin (25 mg/kg) reduced leukocyte rolling by > 90% and significantly reduced leukocyte adhesion, whereas a lower dose of fucoidin still reduced leukocyte rolling by 60% but had no effect on leukocyte adhesion. Moreover, despite the profound reduction in leukocyte rolling with fucoidin, the remaining rolling cells were able to firmly adhere via a CD18-dependent mechanism, particularly in those postcapillary venules with reduced (30-50%) shear rates. The increased rolling was also reduced 60% by either an anti-P-selectin antibody, an anti-L-selectin antibody, or a combination of the two antibodies, but this reduction in rolling cells did not translate into significantly reduced leukocyte adhesion. Our data suggest that L-selectin, P-selectin, and a fucoidin-sensitive pathway contribute to the significant increase in reperfusion-induced leukocyte rolling. However, targeting leukocyte rolling as a form of therapy requires very significant efficacy (> 90%) to achieve reasonable (approximately 50%) attenuation in leukocyte adhesion in postischemic venules. Images PMID:7539452

  11. Indium-111 leukocyte scanning and fracture healing

    SciTech Connect

    Mead, L.P.; Scott, A.C.; Bondurant, F.J.; Browner, B.D. )

    1990-01-01

    This study was undertaken to determine the specificity of indium-111 leukocyte scans for osteomyelitis when fractures are present. Midshaft tibial osteotomies were performed in 14 New Zealand white rabbits, seven of which were infected postoperatively with Staphylococcus aureus per Norden's protocol. All 14 rabbits were scanned following injection with 75 microCi of indium 111 at 72 h after osteotomy and at weekly intervals for 4 weeks. Before the rabbits were killed, the fracture sites were cultured to document the presence or absence of infection. The results of all infected osteotomy sites were positive, whereas no positive scans were found in the noninfected osteotomies. We concluded from this study that uncomplicated fracture healing does not result in a positive indium-111 leukocyte scan.

  12. Fc-rosette inhibition by hypocomplementaemic systemic lupus erythematosus sera.

    PubMed

    Morito, T; Tanimoto, K; Hashimoto, Y; Horiuchi, Y; Juji, T

    1975-10-01

    Human red cells sensitized with one of the Rh antisera (Ripley) form rosettes (Fc-rosette) with human B lymphocytes and the rosettes are well inhibited by aggregated human IgG. Since sera of hypocomplementaemic patients with systemic lupus erythematosus (SLE) have frequently been reported to contain immune complexes, they were used for the inhibition of Fc-rosette formation in this study. The results of Fc-rosette inhibition rates of the sera were inversely correlated with the serum CH50 levels. When the sera were separated into top, middle, and bottom fractions by ultracentrifugation, the bottom fractions showed more effective inhititions than the others. Similarly, the strongest inhibition was found in the void volume of the serum separated by Sephadex G200 gel filtration. Reduction and alkylation of IgG resulted in the loss of reactivity with Fc receptor of B lymphocytes, and the rosette inhibiting activities of the SLE sera were markedly reduced after reduction and alkylation. Some of anti-HLA sera were inhibitory for the Fc-rosette formation, while the tested sera did not contain anti-HLA activity assessed by the microcytotoxicity test. These results indicated that circulating immune complexes contained in the sera inhibit the rosette formation, and that the Fc-rosette inhibition test is a simple and relatively sensitive method for the detection of circulating immune complexes. Antinuclear antibody activities of the sera were tested by the indirect immunofluorescent method; however, clear correlations were not obtained between Fc-rosette inhibition rates and staining patterns of antinuclear antibodies. On the other hand, the positive groups of LE-test exhibited slightly greater inhibition rates of the rosette than the negative groups.

  13. Comparison of technetium-99m-HM-PAO leukocytes with indium-111-oxine leukocytes for localizing intraabdominal sepsis

    SciTech Connect

    Mountford, P.J.; Kettle, A.G.; O'Doherty, M.J.; Coakley, A.J. )

    1990-03-01

    Technetium-99m-HM-PAO (({sup 99m}Tc)HM-PAO) leukocyte and indium-111-oxine (111In-oxine) leukocyte scanning were carried out simultaneously in 41 patients at 4 hr and 24 hr after reinjection to determine whether the 4-hr {sup 99m}Tc scan could replace the 24-hr {sup 111}In scan for detecting intraabdominal sepsis. Abdominal infection was confirmed in 12 cases. The 4-hr {sup 99}Tc-leukocyte scan, the 4-hr {sup 111}In-leukocyte scan, and the 24-hr {sup 111}In-leukocyte scan yielded a sensitivity of 100%, 67%, and 100%, respectively, and a specificity of 62%, 90%, and 86%, respectively. The 24-hr {sup 99m}Tc-leukocyte scan also produced a sensitivity of 100%, but it was falsely positive in all 29 cases without infection due to physiologic bowel uptake. False-positive 4-hr {sup 99m}Tc-leukocyte scans were also produced by physiologic bowel uptake in seven cases all of whom had true-negative 4-hr and 24-hr {sup 111}In-leukocyte scans. Because of the high incidence of false-positive 4-hr ({sup 99m}Tc)HM-PAO leukocyte scans, it was concluded that they could not replace 24-hr {sup 111}In-leukocyte scans for detecting intraabdominal sepsis, and that serial {sup 99m}Tc leukocyte scans starting earlier than 4 hr after reinjection must be evaluated.

  14. CCL20, (gamma)(delta) T cells, and IL-22 in corneal epithelial healing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    After corneal epithelial abrasion, leukocytes and platelets rapidly enter the corneal stroma, and CCR6 (+) IL-17(+) gamma delta T cells migrate into the epithelium. Gamma delta T-cell-deficient (TCRd(-/-)) mice have significantly reduced inflammation and epithelial wound healing. Epithelial CCL20 mR...

  15. Bovine leukocyte adhesion deficiency (BLAD): a review.

    PubMed

    Nagahata, Hajime

    2004-12-01

    Bovine leukocyte adhesion deficiency (BLAD) in Holstein cattle is an autosomal recessive congenital disease characterized by recurrent bacterial infections, delayed wound healing and stunted growth, and is also associated with persistent marked neutrophilia. The molecular basis of BLAD is a single point mutation (adenine to guanine) at position 383 of the CD18 gene, which caused an aspartic acid to glycine substitution at amino acid 128 (D128G) in the adhesion molecule CD18. Neutrophils from BLAD cattle have impaired expression of the beta2 integrin (CD11a,b,c/CD18) of the leukocyte adhesion molecule. Abnormalities in a wide spectrum of adherence dependent functions of leukocytes have been fully characterized. Cattle affected with BLAD have severe ulcers on oral mucous membranes, severe periodontitis, loss of teeth, chronic pneumonia and recurrent or chronic diarrhea. Affected cattle die at an early age due to the infectious complications. Holstein bulls, including carrier sires that had a mutant BLAD gene in heterozygote were controlled from dairy cattle for a decade. The control of BLAD in Holstein cattle by publishing the genotypes and avoiding the mating between BLAD carriers was found to be successful. This paper provides an overview of the genetic disease BLAD with reference to the disease in Holstein cattle. PMID:15644595

  16. Inhibitory FcγRIIb-Mediated Soluble Antigen Clearance from Plasma by a pH-Dependent Antigen-Binding Antibody and Its Enhancement by Fc Engineering

    PubMed Central

    Iwayanagi, Yuki; Maeda, Atsuhiko; Haraya, Kenta; Wada, Naoko A.; Shibahara, Norihito; Ohmine, Ken; Nambu, Takeru; Nakamura, Genki; Mimoto, Futa; Katada, Hitoshi; Ito, Shunsuke; Tachibana, Tatsuhiko; Jishage, Kou-ichi; Hattori, Kunihiro

    2015-01-01

    Fc engineering can modulate the Fc–FcγR interaction and thus enhance the potency of Abs that target membrane-bound Ags, but it has not been applied to Abs that target soluble Ags. In this study, we revealed a previously unknown function of inhibitory FcγRII in vivo and, using an Ab that binds to Ag pH dependently, demonstrated that the function can be exploited to target soluble Ag. Because pH-dependent Ab dissociates Ag in acidic endosome, its Ag clearance from circulation reflects the cellular uptake rate of Ag/Ab complexes. In vivo studies showed that FcγR but not neonatal FcR contributes to Ag clearance by the pH-dependent Ab, and when Fc binding to mouse FcγRII and III was increased, Ag clearance was markedly accelerated in wild-type mice and FcR γ-chain knockout mice, but the effect was diminished in FcγRII knockout mice. This demonstrates that mouse FcγRII efficiently promotes Ab uptake into the cell and its subsequent recycling back to the cell surface. Furthermore, when a human IgG1 Fc variant with selectively increased binding to human FcγRIIb was tested in human FcγRIIb transgenic mice, Ag clearance was accelerated without compromising the Ab half-life. Taken together, inhibitory FcγRIIb was found to play a prominent role in the cellular uptake of monomeric Ag/Ab immune complexes in vivo, and when the Fc of a pH-dependent Ab was engineered to selectively enhance human FcγRIIb binding, the Ab could accelerate soluble Ag clearance from circulation. We assume such a function would enhance the therapeutic potency of Abs that target soluble Ags. PMID:26320252

  17. Dimeric FcγR Ectodomains as Probes of the Fc Receptor Function of Anti-Influenza Virus IgG.

    PubMed

    Wines, Bruce D; Vanderven, Hillary A; Esparon, Sandra E; Kristensen, Anne B; Kent, Stephen J; Hogarth, P Mark

    2016-08-15

    Ab-dependent cellular cytotoxicity, phagocytosis, and Ag presentation are key mechanisms of action of Abs arising in vaccine or naturally acquired immunity, as well of therapeutic mAbs. Cells expressing the low-affinity FcγRs (FcγRII or CD32 and FcγRIII or CD16) are activated for these functions when receptors are aggregated following the binding of IgG-opsonized targets. Despite the diversity of the Fc receptor proteins, IgG ligands, and potential responding cell types, the induction of all FcγR-mediated responses by opsonized targets requires the presentation of multiple Fc regions in close proximity to each other. We demonstrated that such "near-neighbor" Fc regions can be detected using defined recombinant soluble (rs) dimeric low-affinity ectodomains (rsFcγR) that have an absolute binding requirement for the simultaneous engagement of two IgG Fc regions. Like cell surface-expressed FcγRs, the binding of dimeric rsFcγR ectodomains to Ab immune complexes was affected by Ab subclass, presentation, opsonization density, Fc fucosylation, or mutation. The activation of an NK cell line and primary NK cells by human IgG-opsonized influenza A hemagglutinin correlated with dimeric rsFcγRIIIa binding activity but not with Ab titer. Furthermore, the dimeric rsFcγR binding assay sensitively detected greater Fc receptor activity to pandemic H1N1 hemagglutinin after the swine influenza pandemic of 2009 in pooled human polyclonal IgG. Thus these dimeric rsFcγR ectodomains are validated, defined probes that should prove valuable in measuring the immune-activating capacity of IgG Abs elicited by infection or vaccination or experimentally derived IgG and its variants. PMID:27385782

  18. Influence of FcγRIIIb polymorphism on its ability to cooperate with FcγRIIa and CR3 in mediating the oxidative burst of human neutrophils.

    PubMed

    Urbaczek, Ana Carolina; Toller-Kawahisa, Juliana Escher; Fonseca, Luiz Marcos; Costa, Paulo Inácio; Faria, Carolina Maria Quinello Gomes; Azzolini, Ana Elisa Caleiro Seixas; Lucisano-Valim, Yara Maria; Marzocchi-Machado, Cleni Mara

    2014-08-01

    Considering that human neutrophil FcγRIIa and FcγRIIIb receptors interact synergistically with CR3 in triggering neutrophil functional responses, allelic polymorphisms in these receptors might influence such interactions. We assessed whether FcγRIIIb polymorphisms affect FcγR/CR cooperation in mediating the neutrophil oxidative burst (OB), in particular the FcγRIIIb/CR3 cooperation that occurs via lectin-saccharide-like interactions. The OB of human neutrophil antigen (HNA)-1a-, HNA-1b-, and HNA-1a/-1b-neutrophils stimulated with immune complexes, opsonized or not with serum complement, was measured by the luminol-enhanced chemiluminescence assay. Compared with HNA-1a-neutrophils, HNA-1b-neutrophils exhibited reduced FcγR-stimulated OB, but increased FcγR/CR-stimulated OB. It suggests that (i) FcγR and CR cooperate more effectively in HNA-1b-neutrophils, and (ii) the HNA-1b allotype influences the FcγRIIIb cooperation with FcγRIIa, but not with CR3. HNA-1a- and HNA-1b-neutrophils exhibited similar OB responses elicited via CR3 alone or via FcγR/CR-independent pathways. In addition, the level of FcγRIIIb, FcγRIIa, and CR3 expression did not differ significantly among the neutrophil groups studied. Together, these results demonstrate that the HNA-1b allotype influences the functional cooperation between FcγRIIIb and FcγRIIa, and suggest that the difference in the glycosylation pattern between HNA-1a and HNA-1b does not affect the FcγRIIIb cooperation with CR3.

  19. High-affinity immunoglobulin E receptor (Fc epsilon RI)-bearing eosinophils, mast cells, macrophages and Langerhans' cells in allergen-induced late-phase cutaneous reactions in atopic subjects.

    PubMed Central

    Ying, S; Barata, L T; Meng, Q; Grant, J A; Barkans, J; Durham, S R; Kay, A B

    1998-01-01

    We have used in situ hybridization (ISH) and immunohistochemistry (IHC) to investigate the kinetics of the expression for Fc epsilon RI mRNA (alpha-, beta- and gamma-chains), the alpha-chain protein product, as well as the phenotype of the mRNA- or protein-positive cells in allergen-induced late-phase skin reactions in atopic subjects. Compared with diluent controls, there were significant increases in the total number of mRNA+ cells for the alpha-, beta- and gamma-chains for Fc epsilon RI at all time-points (6, 24 and 48 hr) after allergen challenge (P < 0.01). By double IHC/ISH significant increases in alpha-, beta- and gamma-chain mRNA+ macrophages, eosinophils, mast cells and CD1a+ cells were also observed after allergen challenge (P < 0.05). The distribution of Fc epsilon RI subunit (alpha-, beta-, or gamma-chain) mRNA+ co-localization was CD68+ macrophages (42-47%), EG2+ eosinophils (33-39%), tryptase+ mast cells (5-11%) and CD1a+ Langerhans' cells (2-4%). Using single IHC, significant increases in the total number of Fc epsilon RI protein+ cells (P < 0.01) were observed 24 and 48 hr after allergen challenge. Double IHC showed that the distribution of Fc epsilon RI+ cells was tryptase+ mast cells (33%), CD68+ macrophages (36%), EG2+ eosinophils (20%), CD1a+ Langerhans' cells (4%) and unidentified cells (7%), at the 24-hr allergen-challenged sites. These observations suggest that the cutaneous late-phase reaction in man is associated with up-regulation of Fc epsilon RI on eosinophils, macrophages, mast cells and Langerhans' cells. Images Figure 6 PMID:9616380

  20. Chemical macrocyclization of peptides fused to antibody Fc fragments.

    PubMed

    Angelini, Alessandro; Diderich, Philippe; Morales-Sanfrutos, Julia; Thurnheer, Sarah; Hacker, David; Menin, Laure; Heinis, Christian

    2012-09-19

    To extend the plasma half-life of a bicyclic peptide antagonist, we chose to link it to the Fc fragment of the long-lived serum protein IgG1. Instead of chemically conjugating the entire bicyclic peptide, we recombinantly expressed its peptide moiety as a fusion protein to an Fc fragment and subsequently cyclized the peptide by chemically reacting its three cysteine residues with tris-(bromomethyl)benzene. This reaction was efficient and selective, yielding completely modified peptide fusion protein and no side products. After optimization of the linker and the Fc fragment format, the bicyclic peptide was fully functional as an inhibitor (K(i) = 76 nM) and showed an extended terminal half-life of 1.5 days in mice. The unexpectedly clean reaction makes chemical macrocyclization of peptide-Fc fusion proteins an attractive synthetic approach. Its good compatibility with the Fc fragment may lend the bromomethylbenzene-based chemistry also for the generation of antibody-drug conjugates.

  1. Intravital Microscopy of Leukocyte-endothelial and Platelet-leukocyte Interactions in Mesenterial Veins in Mice.

    PubMed

    Herr, Nadine; Mauler, Maximilian; Bode, Christoph; Duerschmied, Daniel

    2015-01-01

    Intravital microscopy is a method that can be used to investigate different processes in different regions and vessels in living animals. In this protocol, we describe intravital microscopy of mesentery veins. This can be performed in a short period of time with reproducible results showing leukocyte-endothelial interactions in vivo. We describe an inflammatory setting after LPS challenge of the endothelium. But in this model one can apply many different types of inflammatory conditions, like bacterial, chemical or biological and investigate the administration of drugs and their direct effects on the living animal and its impact on leukocyte recruitment. This protocol has been applied successfully to a number of different treatments of mice and their effects on inflammatory response in vessels. Herein, we describe the visualization of leukocytes and platelets by fluorescently labeling these with rhodamine 6G. Additionally, any specific imaging can be performed using targeted fluorescently labeled molecules.

  2. Blood leukocyte and spleen lymphocyte immune response of spleen lymphocytes and whole blood leukocytes of hamsters

    SciTech Connect

    Peters, B.A.; Sothmann, M.; Wehrenberg, W.B. )

    1989-01-01

    This study was designed to evaluate the effects of chronic physical activity on the immune response of spleen lymphocytes and whole blood leukocytes of hamsters. Animals were kept sedentary or allowed to exercise spontaneously on running wheels for eight weeks. Physically active animals averaged 12 kilometers per day. The immune response of spleen lymphocytes whole blood leukocytes was evaluated by {sup 3}H-thymidine incorporation in response to Concanavalin A or lipopolysaccharide. There was no treatment effect between physically active and sedentary hamster in response of spleen lymphocytes. The immune response of whole blood leukocytes to these mitogens was significantly greater in physically active vs. sedentary hamsters. These results demonstrate that chronic physical activity has the capacity to modulate immunoresponses.

  3. Leukocyte emigration in normal calves and calves with leukocyte adhesion deficiency.

    PubMed

    Nagahata, H; Masuyama, A; Masue, M; Yuki, M; Higuchi, H; Ohtsuka, H; Kurosawa, T; Sato, H; Noda, H

    1997-12-01

    The emigration of leukocytes from calves with beta 2 integrin deficiency (BLAD) into bronchoalveolar spaces and scraped tissues was compared to that of normal calves. Polymorphonuclear neutrophils were found in bronchoalveolar lavage fluid from BLAD-affected calves showing chronic pneumonia. The neutrophils were complement receptor type 3 (CR3)-negative when characterized by flow cytometric analysis using anti-CD18 monoclonal antibody. Chemiluminescent response mediated by CR3 in neutrophils isolated from bronchoalveolar lavage fluid from BLAD-calves showed similar findings obtained from CR3-deficient neutrophils. Neutrophils from normal calves migrated into scraped tissue which was prepared in an upper gluteal surface area, whereas few leukocytes from calves with BLAD migrated to the scraped tissue, evaluated by skin window (Rebuck) method. These findings confirmed the extravasation of CR3-deficient leukocytes into bronchoalveolar lumen in BLAD calves, and demonstrated in vivo characteristics of extravasating property of normal and CR3-deficient neutrophils into scraped tissues. PMID:9450245

  4. Monovalent Fc receptor blockade by an anti-Fcγ receptor/albumin fusion protein ameliorates murine ITP with abrogated toxicity.

    PubMed

    Yu, Xiaojie; Menard, Melissa; Prechl, József; Bhakta, Varsha; Sheffield, William P; Lazarus, Alan H

    2016-01-01

    Patients with immune thrombocytopenia (ITP) commonly have antiplatelet antibodies that cause thrombocytopenia through Fcγ receptors (FcγRs). Antibodies specific for FcγRs, designed to inhibit antibody-FcγR interaction, had been shown to improve ITP in refractory human patients. However, the development of such FcγR-specific antibodies has stalled because of adverse events, a phenomenon recapitulated in mouse models. One hypothesis behind these adverse events involved the function of the Fc region of the antibody, which engages FcγRs, leading to inflammatory responses. Unfortunately, inhibition of Fc function by deglycosylation failed to prevent this inflammatory response. In this work, we hypothesize that the bivalent antigen-binding fragment regions of immunoglobulin G are sufficient to trigger adverse events and have reasoned that designing a monovalent targeting strategy could circumvent the inflammatory response. To this end, we generated a fusion protein comprising a monovalent human FcγRIIIA-specific antibody linked in tandem to human serum albumin, which retained FcγR-binding activity in vitro. To evaluate clinically relevant in vivo FcγR-blocking function and inflammatory effects, we generated a murine version targeting the murine FcγRIII linked to murine albumin in a passive murine ITP model. Monovalent blocking of FcγR function dramatically inhibited antibody-dependent murine ITP and successfully circumvented the inflammatory response as assessed by changes in body temperature, basophil activation, and basophil depletion. Consistent with our hypothesis, in vivo cross-linking of the fusion protein induced these inflammatory effects, recapitulating the adverse events of the parent antibody. Thus, monovalent blocking of FcγR function demonstrates a proof of concept to successfully treat FcγR-mediated autoimmune diseases.

  5. X-ray Crystal Structures of Monomeric and Dimeric Peptide Inhibitors in Complex with the Human Neonatal Fc Receptor, FcRn

    SciTech Connect

    Mezo, Adam R.; Sridhar, Vandana; Badger, John; Sakorafas, Paul; Nienaber, Vicki

    2010-10-28

    The neonatal Fc receptor, FcRn, is responsible for the long half-life of IgG molecules in vivo and is a potential therapeutic target for the treatment of autoimmune diseases. A family of peptides comprising the consensus motif GHFGGXY, where X is preferably a hydrophobic amino acid, was shown previously to inhibit the human IgG:human FcRn protein-protein interaction (Mezo, A. R., McDonnell, K. A., Tan Hehir, C. A., Low, S. C., Palombella, V. J., Stattel, J. M., Kamphaus, G. D., Fraley, C., Zhang, Y., Dumont, J. A., and Bitonti, A. J. (2008) Proc. Natl. Acad. Sci. U.S.A., 105, 2337-2342). Herein, the x-ray crystal structure of a representative monomeric peptide in complex with human FcRn was solved to 2.6 {angstrom} resolution. The structure shows that the peptide binds to human FcRn at the same general binding site as does the Fc domain of IgG. The data correlate well with structure-activity relationship data relating to how the peptide family binds to human FcRn. In addition, the x-ray crystal structure of a representative dimeric peptide in complex with human FcRn shows how the bivalent ligand can bridge two FcRn molecules, which may be relevant to the mechanism by which the dimeric peptides inhibit FcRn and increase IgG catabolism in vivo. Modeling of the peptide:FcRn structure as compared with available structural data on Fc and FcRn suggest that the His-6 and Phe-7 (peptide) partially mimic the interaction of His-310 and Ile-253 (Fc) in binding to FcRn, but using a different backbone topology.

  6. Compatibility of Fluorinert, FC-72, with selected materials.

    SciTech Connect

    Aubert, James Henry; Sawyer, Patricia Sue

    2006-02-01

    Removable encapsulants have been developed as replacement materials for electronic encapsulation. They can be removed from an electronic assembly in a fairly benign manner. Encapsulants must satisfy a limited number of criteria to be useful. These include processing ease, certain mechanical, thermal, and electrical properties, adhesion to common clean surfaces, good aging characteristics, and compatibility. This report discusses one aspect of the compatibility of removable blown epoxy foams with electronic components. Of interest is the compatibility of the blowing agent, Fluorinert{trademark} (FC-72) electronic fluid with electronic parts, components, and select materials. Excellent compatibility is found with most of the investigated materials. A few materials, such as Teflon{reg_sign} that are comprised of chemicals very similar to FC-72 show substantial absorption of FC-72. No compatibility issues have yet been identified even for the few materials that show substantial absorption.

  7. Comparison of Sample Fixation and the use of LDS-751 or anti-CD45 for Leukocyte Identification in Mouse Whole Blood for Flow Cytometry.

    PubMed Central

    Maes, Melissa L.; Davidson, Lisa; McDonagh, Paul F.; Ritter, Leslie S.

    2007-01-01

    Flow cytometry methods used to measure leukocyte function often entail sample preparation procedures that cause artifactual cell activation. To avoid leukocyte activation by isolation techniques, some preparation methods use fluorescent markers to discriminate leukocytes from erythrocytes in whole blood. One of these markers, laser dye styryl–751(LDS-751), has been used to distinguish leukocytes by staining nucleic acid, but has been found to stain other blood cells and dead cells indiscriminately. Thus, LDS-751 may not be an appropriate reagent for leukocyte identification in whole blood. Fixing samples with formaldehydes increases cell permeability and causes surface protein cross-linking that may alter staining of both intra- and extracellular markers. The degree of this sample alteration by formaldehyde fixation, however, remains in question. In addition, little is known about flow cytometry and sample preparation methods in mouse whole blood. The purpose of this study was to determine if labeling leukocytes with a monoclonal antibody specific to leukocyte common antigen (CD45) was superior to labeling with LDS-751 and to determine the effect of sample fixation on a mouse whole blood preparation for flow cytometry. Samples were incubated with CD16/CD32 Fc receptor blocker, and either 10 μg/ml LDS-751 or phosphate buffered saline (PBS). The samples were then fixed with paraformaldehyde or diluted with PBS followed by incubation with 5ug/ml PerCP-conjugated anti-CD45, 5ug/ml FITC-conjugated anti-CD11b, or 80 μM dichlorofluorescein diacetate. We found that samples labeled with LDS-751 demonstrated decreased fluorescence intensity for granulocyte CD11b expression and ROS production compared to samples labeled with anti-CD45. In addition, sample fixation decreased mean fluorescence intensity in samples labeled with either LDS-751 or anti-CD45. We conclude that labeling leukocytes with monoclonal antibody CD45 in a mouse whole blood preparation is preferable, as

  8. Erythrocyte and leukocyte: two partners in bacteria killing.

    PubMed

    Minasyan, Hayk A

    2014-01-01

    Leukocytes can't perform phagocytosis in blood stream. Blood velocity prevents phagocytosis because there is no time for leukocyte to recognize and catch bacteria. Bloodstream clearance from pathogens is performed by erythrocytes. During motion in bloodstream erythrocytes become charged by triboelectric effect. This charge attracts bacteria and fixes them on the surface of erythrocyte, then bacteria are engulfed and killed by hemoglobin oxygen. In bloodstream, leukocyte thin-wrinkled elastic membrane can't be charged by triboelectric effect and so leukocyte can't catch bacteria by means of electrostatic attraction force. Leukocytes engulf and kill bacteria out of blood circulatory system: in tissues, lymph nodes, slow velocity lymph, etc. Erythrocyte and leukocyte are bactericidal partners: the first kills bacteria in bloodstream, the second kills them locally, out of blood circulation.

  9. Indium-111 leukocyte imaging in patients with rheumatoid arthritis

    SciTech Connect

    Uno, K.; Matsui, N.; Nohira, K.; Suguro, T.; Kitakata, Y.; Uchiyama, G.; Miyoshi, T.; Uematsu, S.; Inoue, S.; Arimizu, N.

    1986-03-01

    This study evaluates the usefulness of labeled leukocyte imaging in patients with rheumatoid arthritis. In 33 patients, the incidence of pain and swelling in 66 wrist joints and 66 knee joints was compared with the accumulation of (/sup 111/In)leukocytes. No accumulation of (/sup 111/In)leukocytes was seen in any of the patients' wrists (0/12) or knee joints (0/14) when both pain and swelling were absent. In contrast, 93% (25/27) of wrist joints and 80% (24/30) of knee joints with both pain and swelling were positive by (/sup 111/In)leukocyte scintigraphy. There was little correlation between the stage of the disease, as determined by radiography, and (/sup 111/In)leukocyte accumulation. This study suggests that (/sup 111/In)leukocyte imaging may be a reliable procedure for monitoring the activity of rheumatoid arthritis, especially for confirming the lack of an ongoing inflammatory response.

  10. Sperm DNA damage and its relation with leukocyte DNA damage.

    PubMed

    Babazadeh, Zahra; Razavi, Shahnaz; Tavalaee, Marziyeh; Deemeh, Mohammad Reza; Shahidi, Maryam; Nasr-Esfahani, Mohammad Hossein

    2010-01-01

    DNA fragmentation in human sperm has been related to endogenous and exogenous factors. Exogenous factors can also affect leukocyte DNA integrity. This study evaluated the relation between sperm DNA damage and leukocyte DNA integrity, as a predictor of exogenous factors. DNA damage in the sperm and leukocytes of 41 individuals undergoing ICSI were measured by Comet assay. In addition, sperm chromatin dispersion (SCD) was carried out on semen samples. A positive correlation was observed between the DNA integrity of sperm with leukocytes. When patients were divided into low and high DNA exposure groups, sperm DNA fragmentation was significantly different between the two groups. Cleavage rate and embryo quality showed significant correlation with leukocyte DNA integrity. The results showed that leukocyte DNA integrity could be used to identify individuals at high risk in order to reduce the extent of DNA damage in patients before ICSI in order to improve the subsequent outcome of this procedure.

  11. Fc receptors for immunoglobulins and their appearance during vertebrate evolution.

    PubMed

    Akula, Srinivas; Mohammadamin, Sayran; Hellman, Lars

    2014-01-01

    Receptors interacting with the constant domain of immunoglobulins (Igs) have a number of important functions in vertebrates. They facilitate phagocytosis by opsonization, are key components in antibody-dependent cellular cytotoxicity as well as activating cells to release granules. In mammals, four major types of classical Fc receptors (FcRs) for IgG have been identified, one high-affinity receptor for IgE, one for both IgM and IgA, one for IgM and one for IgA. All of these receptors are related in structure and all of them, except the IgA receptor, are found in primates on chromosome 1, indicating that they originate from a common ancestor by successive gene duplications. The number of Ig isotypes has increased gradually during vertebrate evolution and this increase has likely been accompanied by a similar increase in isotype-specific receptors. To test this hypothesis we have performed a detailed bioinformatics analysis of a panel of vertebrate genomes. The first components to appear are the poly-Ig receptors (PIGRs), receptors similar to the classic FcRs in mammals, so called FcRL receptors, and the FcR γ chain. These molecules are not found in cartilagous fish and may first appear within bony fishes, indicating a major step in Fc receptor evolution at the appearance of bony fish. In contrast, the receptor for IgA is only found in placental mammals, indicating a relatively late appearance. The IgM and IgA/M receptors are first observed in the monotremes, exemplified by the platypus, indicating an appearance during early mammalian evolution. Clearly identifiable classical receptors for IgG and IgE are found only in marsupials and placental mammals, but closely related receptors are found in the platypus, indicating a second major step in Fc receptor evolution during early mammalian evolution, involving the appearance of classical IgG and IgE receptors from FcRL molecules and IgM and IgA/M receptors from PIGR. PMID:24816777

  12. Interleukin-18 Induces Acute Biphasic Reduction in the Levels of Circulating Leukocytes in Mice

    PubMed Central

    Hosohara, Katsushi; Ueda, Haruyasu; Kashiwamura, Shin-Ichiro; Yano, Takako; Ogura, Takeharu; Marukawa, Seishiro; Okamura, Haruki

    2002-01-01

    We investigated the acute hematological changes caused by interleukin-18 (IL-18) in mice. Intraperitoneal administration of IL-18 (2 μg/mouse) resulted in biphasic decreases in the number of leukocytes in the blood. The first phase of decrease occurred within 2 h of IL-18 administration and was followed by a transient increase at 5 h. The second phase of decrease occurred at around 6 h, reaching a nadir which lasted for more than 24 h. In mice deficient in inducible nitric oxide (NO) synthase, the first phase of reduction of leukocytes did not occur although the second phase of decrease was observed. In mice deficient in gamma interferon (IFN-γ) or in mice depleted of natural killer cells and incapable of producing IFN-γ, IL-18 had no effect on the number of circulating leukocytes. Levels of nitrite and/or nitrate in the serum were elevated within 2 h after administration of IL-18, reaching a peak at 4 h and then decreasing gradually to the basal level over a 24-h period of time. On the other hand, serum IFN-γ levels changed in a biphasic manner, reaching a peak at 2 h after IL-18 administration, followed by a decrease in the basal level and a second increase at 6 h. Levels of IL-18 receptor mRNAs also showed biphasic changes in correlation with the changes in serum IFN-γ levels. These results suggest that the changes in the leukocyte number following IL-18 administration are mediated by NO and IFN-γ, with NO being involved in the first phase of reduction and IFN-γ being involved in both phases. PMID:12093672

  13. Intravital leukocyte detection using the gradient inverse coefficient of variation.

    PubMed

    Dong, Gang; Ray, Nilanjan; Acton, Scott T

    2005-07-01

    The problem of identifying and counting rolling leukocytes within intravital microscopy is of both theoretical and practical interest. Currently, methods exist for tracking rolling leukocytes in vivo, but these methods rely on manual detection of the cells. In this paper we propose a technique for accurately detecting rolling leukocytes based on Bayesian classification. The classification depends on a feature score, the gradient inverse coefficient of variation (GICOV), which serves to discriminate rolling leukocytes from a cluttered environment. The leukocyte detection process consists of three sequential steps: the first step utilizes an ellipse matching algorithm to coarsely identify the leukocytes by finding the ellipses with a locally maximal GICOV. In the second step, starting from each of the ellipses found in the first step, a B-spline snake is evolved to refine the leukocytes boundaries by maximizing the associated GICOV score. The third and final step retains only the extracted contours that have a GICOV score above the analytically determined threshold. Experimental results using 327 rolling leukocytes were compared to those of human experts and currently used methods. The proposed GICOV method achieves 78.6% leukocyte detection accuracy with 13.1% false alarm rate.

  14. Analysis of leukocyte rolling in vivo and in vitro.

    PubMed

    Sperandio, Markus; Pickard, John; Unnikrishnan, Sunil; Acton, Scott T; Ley, Klaus

    2006-01-01

    Leukocyte rolling is an important step for the successful recruitment of leukocytes from blood to tissues mediated by a specialized group of glycoproteins termed selectins. Because of the dynamic process of leukocyte rolling, binding of selectins to their respective counter-receptors (selectin ligands) needs to fulfill three major requirements: (1) rapid bond formation, (2) high tensile strength, and (3) fast dissociation rates. These criteria are perfectly met by selectins, which interact with specific carbohydrate determinants on selectin ligands. This chapter describes the theoretical background, technical requirements, and analytical tools needed to quantitatively assess leukocyte rolling in vivo and in vitro. For the in vivo setting, intravital microscopy allows the observation and recording of leukocyte rolling under different physiological and pathological conditions in almost every organ. Real-time and off-line analysis tools help to assess geometric, hemodynamic, and rolling parameters. Under in vitro conditions, flow chamber assays such as parallel plate flow chamber systems have been the mainstay to study interactions between leukocytes and adhesion molecules under flow. In this setting, adhesion molecules are immobilized on plastic, in a lipid monolayer, or presented on cultured endothelial cells on the chamber surface. Microflow chambers are available for studying leukocyte adhesion in the context of whole blood and without blood cell isolation. The microscopic observation of leukocyte rolling in different in vivo and in vitro settings has significantly contributed to our understanding of the molecular mechanisms responsible for the stepwise extravasation of leukocytes into inflamed tissues.

  15. Single-domain antibody-based and linker-free bispecific antibodies targeting FcγRIII induce potent antitumor activity without recruiting regulatory T cells.

    PubMed

    Rozan, Caroline; Cornillon, Amélie; Pétiard, Corinne; Chartier, Martine; Behar, Ghislaine; Boix, Charlotte; Kerfelec, Brigitte; Robert, Bruno; Pèlegrin, André; Chames, Patrick; Teillaud, Jean-Luc; Baty, Daniel

    2013-08-01

    Antibody-dependent cell-mediated cytotoxicity, one of the most prominent modes of action of antitumor antibodies, suffers from important limitations due to the need for optimal interactions with Fcγ receptors. In this work, we report the design of a new bispecific antibody format, compact and linker-free, based on the use of llama single-domain antibodies that are capable of circumventing most of these limitations. This bispecific antibody format was created by fusing single-domain antibodies directed against the carcinoembryonic antigen and the activating FcγRIIIa receptor to human Cκ and CH1 immunoglobulin G1 domains, acting as a natural dimerization motif. In vitro and in vivo characterization of these Fab-like bispecific molecules revealed favorable features for further development as a therapeutic molecule. They are easy to produce in Escherichia coli, very stable, and elicit potent lysis of tumor cells by human natural killer cells at picomolar concentrations. Unlike conventional antibodies, they do not engage inhibitory FcγRIIb receptor, do not compete with serum immunoglobulins G for receptor binding, and their cytotoxic activity is independent of Fc glycosylation and FcγRIIIa polymorphism. As opposed to anti-CD3 bispecific antitumor antibodies, they do not engage regulatory T cells as these latter cells do not express FcγRIII. Studies in nonobese diabetic/severe combined immunodeficient gamma mice xenografted with carcinoembryonic antigen-positive tumor cells showed that Fab-like bispecific molecules in the presence of human peripheral blood mononuclear cells significantly slow down tumor growth. This new compact, linker-free bispecific antibody format offers a promising approach for optimizing antibody-based therapies.

  16. The neonatal Fc receptor (FcRn) binds independently to both sites of the IgG homodimer with identical affinity

    PubMed Central

    Abdiche, Yasmina Noubia; Yeung, Yik Andy; Chaparro-Riggers, Javier; Barman, Ishita; Strop, Pavel; Chin, Sherman Michael; Pham, Amber; Bolton, Gary; McDonough, Dan; Lindquist, Kevin; Pons, Jaume; Rajpal, Arvind

    2015-01-01

    The neonatal Fc receptor (FcRn) is expressed by cells of epithelial, endothelial and myeloid lineages and performs multiple roles in adaptive immunity. Characterizing the FcRn/IgG interaction is fundamental to designing therapeutic antibodies because IgGs with moderately increased binding affinities for FcRn exhibit superior serum half-lives and efficacy. It has been hypothesized that 2 FcRn molecules bind an IgG homodimer with disparate affinities, yet their affinity constants are inconsistent across the literature. Using surface plasmon resonance biosensor assays that eliminated confounding experimental artifacts, we present data supporting an alternate hypothesis: 2 FcRn molecules saturate an IgG homodimer with identical affinities at independent sites, consistent with the symmetrical arrangement of the FcRn/Fc complex observed in the crystal structure published by Burmeister et al. in 1994. We find that human FcRn binds human IgG1 with an equilibrium dissociation constant (KD) of 760 ± 60 nM (N = 14) at 25°C and pH 5.8, and shows less than 25% variation across the other human subtypes. Human IgG1 binds cynomolgus monkey FcRn with a 2-fold higher affinity than human FcRn, and binds both mouse and rat FcRn with a 10-fold higher affinity than human FcRn. FcRn/IgG interactions from multiple species show less than a 2-fold weaker affinity at 37°C than at 25°C and appear independent of an IgG's variable region. Our in vivo data in mouse and rat models demonstrate that both affinity and avidity influence an IgG's serum half-life, which should be considered when choosing animals, especially transgenic systems, as surrogates. PMID:25658443

  17. Fc-glycosylation influences Fcγ receptor binding and cell-mediated anti-HIV activity of monoclonal antibody 2G12.

    PubMed

    Forthal, Donald N; Gach, Johannes S; Landucci, Gary; Jez, Jakub; Strasser, Richard; Kunert, Renate; Steinkellner, Herta

    2010-12-01

    Interactions between the Fc segment of IgG and FcγRs on a variety of cells are likely to play an important role in the anti-HIV activity of Abs. Because the nature of the glycan structure on the Fc domain is a critical determinant of Fc-FcγR binding, proper Fc glycosylation may contribute to Ab-mediated protection. We have generated five different glycoforms of the broadly HIV-1-neutralizing mAb 2G12 in wild-type and glycoengineered plants and Chinese hamster ovary cells. Plant-derived 2G12 exhibited highly homogeneous glycosylation profiles with a single dominant N-glycan species. Using flow cytometry with FcγR-expressing cell lines, all 2G12 glycoforms demonstrated similar binding to FcγRI, FcγRIIa, and FcγRIIb. In contrast, two glycoforms derived from glycoengineered plants that lack plant-specific xylose and core α1,3-fucose, and instead carry human-like glycosylation with great uniformity, showed significantly enhanced binding to FcγRIIIa compared with Chinese hamster ovary or wild-type plant-derived 2G12. Using surface plasmon resonance, we show that binding of 2G12 to FcγRIIIa is markedly affected by core fucose, irrespective of its plant-specific α1,3 or mammalian-type α1,6 linkage. Consistent with this finding, 2G12 glycoforms lacking core fucose (and xylose) mediated higher antiviral activity against HIV-1 or simian immunodeficiency virus as measured by Ab-dependent cell-mediated virus inhibition. This is, to our knowledge, the first demonstration that specific alterations of Fc glycosylation can improve antiviral activity. Such alterations may result in better immunotherapeutic reagents. Moreover, biasing vaccine-induced immune responses toward optimal Fc glycosylation patterns could result in improved vaccine efficacy. PMID:21041724

  18. Fröhlich electromagnetic radiation from human leukocytes: implications for leukocyte adherence inhibition test.

    PubMed

    Pokorný, J; Jandová, A; Kobilková, J; Heyberger, K; Hraba, T

    1983-05-21

    The Fröhlich coherent vibrations may be a source of an electromagnetic field generated by living cells in the frequency range from 0.1 to 10 THz. The electromagnetic field may cause the time dependent orientation (i.e. rotation or rocking) of the polar molecules of the ambient liquid medium and may attract them. The attracted molecules move together with the cell and the friction coefficient of the cellular motion, therefore, may depend on the field. The cell-generated electromagnetic field may interact with the surface charge of various solid-state materials causing attractive forces. These interaction attractive forces may be significant in the process of the leukocyte adherence to the surfaces of various materials. The hypothesis presented in this paper assumes that the exposition of leukocytes from immune individuals to antigen causes changes of the Fröhlich coherent vibrations resulting in decrease of the leukocyte adherence observed in the leukocyte adherence inhibition test. PMID:6348422

  19. RELEASE OF CARTILAGE MUCOPOLYSACCHARIDE-DEGRADING NEUTRAL PROTEASE FROM HUMAN LEUKOCYTES

    PubMed Central

    Oronsky, A.; Ignarro, L.; Perper, R.

    1973-01-01

    The granule fraction of human leukocytes contains neutral protease capable of degrading the noncollagenous protein mucopolysaccharide matrix of cartilage at neutral pH in physiological salt solution. Cartilage degradation was monitored by quantitating the release of 35S from labeled rabbit ear cartilage. Degradation of cartilage matrix occurs when intact viable human leukocytes are incubated with cartilage opsonized with aggregated human gamma globulin (AHGG). During a similar 4 h incubation period cells did not degrade uncoated cartilage or cartilage coated with nonaggregated gamma globulin. Cells remain viable during the enzyme release process as evidenced by the absence of a cytoplasmic enzyme marker (lactic dehydrogenase) in the supernatant and dye exclusion studies. The release of 35S from labeled cartilage by human leukocytes in the presence of cartilage coated with AHGG (nonphagocytic enzyme release) was compared with the cartilage degrading activity of the supernatant from the same number of cells preincubated with a suspension of AHGG (phagocytic enzyme release). Nonphagocytic enzyme release by 5 x 106 cells provoked two to four times more 35S and β-glucuronidase (β-G) release from cartilage than phagocytic enzyme release conditions. β-glucuronidase was used as an indicator of the release of lysosomal granule enzymes. By the use of selected pharmacological agents it was possible to dissociate the enzyme release process from intrinsic enzyme (neutral protease) activity. Neutral protease and β-G release by human cells in the presence of AHGG-coated cartilage was inhibited by 10–5M colchicine, whereas the protease activity, but not the release process, was inhibited by 10–6M gold thiomalate and 10% human serum. It is suggested that the release of a cartilage degrading neutral protease by viable human cells when exposed to AHGG might be a relevant model for the study of cartilage destruction as it occurs in rheumatoid arthritis. PMID:4124211

  20. FcRn Rescues Recombinant Factor VIII Fc Fusion Protein from a VWF Independent FVIII Clearance Pathway in Mouse Hepatocytes

    PubMed Central

    van der Flier, Arjan; Liu, Zhan; Tan, Siyuan; Chen, Kai; Drager, Douglas; Liu, Tongyao; Patarroyo-White, Susannah; Jiang, Haiyan; Light, David R.

    2015-01-01

    We recently developed a longer lasting recombinant factor VIII-Fc fusion protein, rFVIIIFc, to extend the half-life of replacement FVIII for the treatment of people with hemophilia A. In order to elucidate the biological mechanism for the elongated half-life of rFVIIIFc at a cellular level we delineated the roles of VWF and the tissue-specific expression of the neonatal Fc receptor (FcRn) in the biodistribution, clearance and cycling of rFVIIIFc. We find the tissue biodistribution is similar for rFVIIIFc and rFVIII and that liver is the major clearance organ for both molecules. VWF reduces the clearance and the initial liver uptake of rFVIIIFc. Pharmacokinetic studies in FcRn chimeric mice show that FcRn expressed in somatic cells (hepatocytes or liver sinusoidal endothelial cells) mediates the decreased clearance of rFVIIIFc, but FcRn in hematopoietic cells (Kupffer cells) does not affect clearance. Immunohistochemical studies show that when rFVIII or rFVIIIFc is in dynamic equilibrium binding with VWF, they mostly co localize with VWF in Kupffer cells and macrophages, confirming a major role for liver macrophages in the internalization and clearance of the VWF-FVIII complex. In the absence of VWF a clear difference in cellular localization of VWF-free rFVIII and rFVIIIFc is observed and neither molecule is detected in Kupffer cells. Instead, rFVIII is observed in hepatocytes, indicating that free rFVIII is cleared by hepatocytes, while rFVIIIFc is observed as a diffuse liver sinusoidal staining, suggesting recycling of free-rFVIIIFc out of hepatocytes. These studies reveal two parallel linked clearance pathways, with a dominant pathway in which both rFVIIIFc and rFVIII complexed with VWF are cleared mainly by Kupffer cells without FcRn cycling. In contrast, the free fraction of rFVIII or rFVIIIFc unbound by VWF enters hepatocytes, where FcRn reduces the degradation and clearance of rFVIIIFc relative to rFVIII by cycling rFVIIIFc back to the liver sinusoid and

  1. Measles virus-induced changes in leukocyte function antigen 1 expression and leukocyte aggregation: possible role in measles virus pathogenesis.

    PubMed

    Attibele, N; Wyde, P R; Trial, J; Smole, S C; Smith, C W; Rossen, R D

    1993-02-01

    Measles virus (MV) infection of U937 cell or peripheral blood leukocyte cultures was shown to induce changes in the expression of leukocyte function antigen 1 (LFA-1) and cause marked aggregation of these cells. Addition of selected monoclonal antibodies specific for LFA-1 epitopes that did not neutralize MV in standard neutralization assays were found to block both virus-induced leukocyte aggregation and virus dissemination. These data suggest that MV modulation of LFA-1 expression on leukocytes may be an important step in MV pathogenesis.

  2. Targeting FcRn for the modulation of antibody dynamics.

    PubMed

    Ward, E Sally; Devanaboyina, Siva Charan; Ober, Raimund J

    2015-10-01

    The MHC class I-related receptor, FcRn, is a multitasking protein that transports its IgG ligand within and across cells of diverse origins. The role of this receptor as a global regulator of IgG homeostasis and transport, combined with knowledge of the molecular details of FcRn-IgG interactions, has led to opportunities to modulate the in vivo dynamics of antibodies and their antigens through protein engineering. Consequently, the generation of half-life extended antibodies has shown a rapid expansion over the past decade. Further, FcRn itself can be targeted by inhibitors to induce decreased levels of circulating IgGs, which could have applications in multiple clinical settings. The engineering of antibody-antigen interactions to reduce antibody-mediated buffering of soluble ligand has also developed into an active area of investigation, leading to novel antibody platforms designed to result in more effective antigen clearance. Similarly, the target-mediated elimination of antibodies by internalizing, membrane bound antigens (receptors) can be decreased using novel engineering approaches. These strategies, combined with subcellular trafficking analyses of antibody/antigen/FcRn behavior in cells to predict in vivo behavior, have considerable promise for the production of next generation therapeutics and diagnostics.

  3. Targeting FcRn for the modulation of antibody dynamics

    PubMed Central

    Ward, E. Sally; Devanaboyina, Siva Charan; Ober, Raimund J.

    2015-01-01

    The MHC Class I-related receptor, FcRn, is a multitasking protein that transports its IgG ligand within and across cells of diverse origins. The role of this receptor as a global regulator of IgG homeostasis and transport, combined with knowledge of the molecular details of FcRn-IgG interactions, has led to opportunities to modulate the in vivo dynamics of antibodies and their antigens through protein engineering. Consequently, the generation of half-life extended antibodies has shown a rapid expansion over the past decade. Further, FcRn itself can be targeted by inhibitors to induce decreased levels of circulating IgGs, which could have applications in multiple clinical settings. The engineering of antibody-antigen interactions to reduce antibody-mediated buffering of soluble ligand has also developed into an active area of investigation, leading to novel antibody platforms designed to lead to more effective antigen clearance. Similarly, the target-mediated elimination of antibodies by internalizing, membrane bound antigens (receptors) can be decreased using novel engineering approaches. These strategies, combined with subcellular trafficking analyses of antibody/antigen/FcRn behavior in cells to predict in vivo behavior, have considerable promise for the production of next generation therapeutics and diagnostics. PMID:25766596

  4. Platelets deficient in glycoprotein I have normal Fc receptor expression.

    PubMed

    Pfueller, S L; de Rosbo, N K; Bilston, R A

    1984-04-01

    Platelet glycoprotein I (GPI) is known to be required for the interaction of platelets with ristocetin and factor VIII:von Willebrand factor (VIII:vWf). However, its role as Fc receptor is not clear. Some studies have shown that enzymatic removal of GPI destroys the ability of platelets to react with VIII:vWf but not their ability to bind Ig G (IgG). Others have shown that IgG immune complexes which block the Fc receptor also inhibit VIII:vWf interaction with platelets. This subject has been re-examined by testing the ability of platelets with reduced amounts of GPI to aggregate and undergo the release reaction in response to stimuli which act at the platelet Fc receptor. Platelets from two patients with Bernard-Soulier syndrome, congenitally deficient in GPI, both aggregated and released 14C-serotonin normally when exposed to latex particles coated with IgG. Levels of GPI were decreased experimentally in normal platelets by treating them with chymotrypsin. Platelets treated in this manner did not aggregate or release [14C]serotonin in response to ristocetin-VIII:vWf. They did, however, both aggregate and release when incubated with heat-aggregated IgG, antigen-antibody complexes or latex particles coated with IgG. Thus the presence of GPI is not a prerequisite for platelet stimulation via the Fc receptor. PMID:6231945

  5. HAL/S-FC compiler system functional specification

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Compiler organization is discussed, including overall compiler structure, internal data transfer, compiler development, and code optimization. The user, system, and SDL interfaces are described, along with compiler system requirements. Run-time software support package and restrictions and dependencies are also considered of the HAL/S-FC system.

  6. Photon Counts Statistics in Leukocyte Cell Dynamics

    NASA Astrophysics Data System (ADS)

    van Wijk, Eduard; van der Greef, Jan; van Wijk, Roeland

    2011-12-01

    In the present experiment ultra-weak photon emission/ chemiluminescence from isolated neutrophils was recorded. It is associated with the production of reactive oxygen species (ROS) in the "respiratory burst" process which can be activated by PMA (Phorbol 12-Myristate 13-Acetate). Commonly, the reaction is demonstrated utilizing the enhancer luminol. However, with the use of highly sensitive photomultiplier equipment it is also recorded without enhancer. In that case, it can be hypothesized that photon count statistics may assist in understanding the underlying metabolic activity and cooperation of these cells. To study this hypothesis leukocytes were stimulated with PMA and increased photon signals were recorded in the quasi stable period utilizing Fano factor analysis at different window sizes. The Fano factor is defined by the variance over the mean of the number of photon within the observation time. The analysis demonstrated that the Fano factor of true signal and not of the surrogate signals obtained by random shuffling increases when the window size increased. It is concluded that photon count statistics, in particular Fano factor analysis, provides information regarding leukocyte interactions. It opens the perspective to utilize this analytical procedure in (in vivo) inflammation research. However, this needs further validation.

  7. Leukocytes segmentation using Markov random fields.

    PubMed

    Reta, C; Gonzalez, J A; Diaz, R; Guichard, J S

    2011-01-01

    The segmentation of leukocytes and their components plays an important role in the extraction of geometric, texture, and morphological characteristics used to diagnose different diseases. This paper presents a novel method to segment leukocytes and their respective nucleus and cytoplasm from microscopic bone marrow leukemia cell images. Our method uses color and texture contextual information of image pixels to extract cellular elements from images, which show heterogeneous color and texture staining and high-cell population. The CIEL ( ∗ ) a ( ∗ ) b ( ∗ ) color space is used to extract color features, whereas a 2D Wold Decomposition model is applied to extract structural and stochastic texture features. The color and texture contextual information is incorporated into an unsupervised binary Markov Random Field segmentation model. Experimental results show the performance of the proposed method on both synthetic and real leukemia cell images. An average accuracy of 95% was achieved in the segmentation of real cell images by comparing those results with manually segmented cell images.

  8. Contribution of Human FcγRs to Disease with Evidence from Human Polymorphisms and Transgenic Animal Studies

    PubMed Central

    Gillis, Caitlin; Gouel-Chéron, Aurélie; Jönsson, Friederike; Bruhns, Pierre

    2014-01-01

    The biological activities of human IgG antibodies predominantly rely on a family of receptors for the Fc portion of IgG, FcγRs: FcγRI, FcγRIIA, FcγRIIB, FcγRIIC, FcγRIIIA, FcγRIIIB, FcRL5, FcRn, and TRIM21. All FcγRs bind IgG at the cell surface, except FcRn and TRIM21 that bind IgG once internalized. The affinity of FcγRs for IgG is determined by polymorphisms of human FcγRs and ranges from 2 × 104 to 8 × 107 M−1. The biological functions of FcγRs extend from cellular activation or inhibition, IgG-internalization/endocytosis/phagocytosis to IgG transport and recycling. This review focuses on human FcγRs and intends to present an overview of the current understanding of how these receptors may contribute to various pathologies. It will define FcγRs and their polymorphic variants, their affinity for human IgG subclasses, and review the associations found between FcγR polymorphisms and human pathologies. It will also describe the human FcγR-transgenic mice that have been used to study the role of these receptors in autoimmune, inflammatory, and allergic disease models. PMID:24910634

  9. Positive indium-111 leukocyte scintigraphy in a skeletal metastasis

    SciTech Connect

    Sfakianakis, G.N.; Mnaymneh, W.; Ghandur-Mnaymneh, L.; Al-Sheikh, W.; Hourani, M.; Heal, A.

    1982-09-01

    Indium-111 scintigraphy is a method proposed for specific diagnosis and localization of focal infection. It has been found that, in general, cancers did not visualize with leukocyte scintigraphy. In this article, a case of positive indium-111 leukocyte scintigrams of a foot metstasis from a mucoepidermoid carcinoma of the lung is reported. (JMT)

  10. Isolation of Leukocytes from the Human Maternal-fetal Interface.

    PubMed

    Xu, Yi; Plazyo, Olesya; Romero, Roberto; Hassan, Sonia S; Gomez-Lopez, Nardhy

    2015-01-01

    Pregnancy is characterized by the infiltration of leukocytes in the reproductive tissues and at the maternal-fetal interface (decidua basalis and decidua parietalis). This interface is the anatomical site of contact between maternal and fetal tissues; therefore, it is an immunological site of action during pregnancy. Infiltrating leukocytes at the maternal-fetal interface play a central role in implantation, pregnancy maintenance, and timing of delivery. Therefore, phenotypic and functional characterizations of these leukocytes will provide insight into the mechanisms that lead to pregnancy disorders. Several protocols have been described in order to isolate infiltrating leukocytes from the decidua basalis and decidua parietalis; however, the lack of consistency in the reagents, enzymes, and times of incubation makes it difficult to compare these results. Described herein is a novel approach that combines the use of gentle mechanical and enzymatic dissociation techniques to preserve the viability and integrity of extracellular and intracellular markers in leukocytes isolated from the human tissues at the maternal-fetal interface. Aside from immunophenotyping, cell culture, and cell sorting, the future applications of this protocol are numerous and varied. Following this protocol, the isolated leukocytes can be used to determine DNA methylation, expression of target genes, in vitro leukocyte functionality (i.e., phagocytosis, cytotoxicity, T-cell proliferation, and plasticity, etc.), and the production of reactive oxygen species at the maternal-fetal interface. Additionally, using the described protocol, this laboratory has been able to describe new and rare leukocytes at the maternal-fetal interface.

  11. The effects of stress on the enzymes of peripheral leukocytes

    NASA Technical Reports Server (NTRS)

    Leise, E. M.; Gray, I.

    1973-01-01

    Previous work showed an early response of rabbit and human leukocyte enzymes to the stress of bacterial infection. Since these represented a mixed population of leukocytes and since polymorphonuclear leukocytes (PMN) increased in these preparations, it was necessary to establish whether the observed increase in lactate dehydrenase (LDH) and protein was the result of an increase in any one particular cell type or in all cells. The need for the development of a simple reproducible method for the differential separation of peripheral leukocytes for the furtherance of our own studies was apparent. It was also becoming increasingly apparent that morphologically similar cells, such as small lymphocytes (L) and macrophages, were capable of different biological functions. A dextran gradient centrifugation method was developed which has provided an easily reproducible technique for separating L from PMN. During the course of this work, in which over 250 rabbits were examined, the pattern of daily leukocyte protein and enzyme variation became increasingly more apparent. This information could have some impact on future work with leukocyte enzymes, by our group and by other workers. The differences in normal protein and enzyme levels maintained by some individuals, and some inbred strains, were evaluated and reported separately. It has been shown that one type of leukocyte may react more to a given stress than other leukocytes.

  12. [Bovine leukocyte adhesion deficiency: clinical picture and differential diagnosis].

    PubMed

    Lienau, A; Stöber, M; Kehrli, M E; Tammen, I; Schwenger, B; Kuczka, A; Pohlenz, J

    1994-10-01

    The pathological clinical and laboratory findings obtained in 50 calves and young cattle affected with Bovine Leukocyte Adhesion Deficiency are compared with those found in 114 calves and young cattle showing marked neutrophil leukocytosis of other origin (age: < 2 years; leukocyte count: > 30,000 per microl; percentage of lymphocytes: < 55%). PMID:7851303

  13. Asymmetrical Fc Engineering Greatly Enhances Antibody-dependent Cellular Cytotoxicity (ADCC) Effector Function and Stability of the Modified Antibodies*

    PubMed Central

    Liu, Zhi; Gunasekaran, Kannan; Wang, Wei; Razinkov, Vladimir; Sekirov, Laura; Leng, Esther; Sweet, Heather; Foltz, Ian; Howard, Monique; Rousseau, Anne-Marie; Kozlosky, Carl; Fanslow, William; Yan, Wei

    2014-01-01

    Antibody-dependent cellular cytotoxicity (ADCC) is mediated through the engagement of the Fc segment of antibodies with Fcγ receptors (FcγRs) on immune cells upon binding of tumor or viral antigen. The co-crystal structure of FcγRIII in complex with Fc revealed that Fc binds to FcγRIII asymmetrically with two Fc chains contacting separate regions of the FcγRIII by utilizing different residues. To fully explore this asymmetrical nature of the Fc-FcγR interaction, we screened more than 9,000 individual clones in Fc heterodimer format in which different mutations were introduced at the same position of two Fc chains using a high throughput competition AlphaLISA® assay. To this end, we have identified a panel of novel Fc variants with significant binding improvement to FcγRIIIA (both Phe-158 and Val-158 allotypes), increased ADCC activity in vitro, and strong tumor growth inhibition in mice xenograft human tumor models. Compared with previously identified Fc variants in conventional IgG format, Fc heterodimers with asymmetrical mutations can achieve similar or superior potency in ADCC-mediated tumor cell killing and demonstrate improved stability in the CH2 domain. Fc heterodimers also allow more selectivity toward activating FcγRIIA than inhibitory FcγRIIB. Afucosylation of Fc variants further increases the affinity of Fc to FcγRIIIA, leading to much higher ADCC activity. The discovery of these Fc variants will potentially open up new opportunities of building the next generation of therapeutic antibodies with enhanced ADCC effector function for the treatment of cancers and infectious diseases. PMID:24311787

  14. Tissue stroma as a regulator of leukocyte recruitment in inflammation.

    PubMed

    McGettrick, Helen M; Butler, Lynn M; Buckley, Chris D; Rainger, G Ed; Nash, Gerard B

    2012-03-01

    The stromal milieu (cellular and matrix components) helps establish tissue "address-codes" that direct leukocyte behavior in inflamed tissue. Coordinated interactions among the stroma, leukocytes, and ECs dictate which leukocytes are recruited, whether they are retained within the inflamed site, and how long they survive. Herein, we discuss how the stromal milieu influences the leukocyte recruitment cascade. Moreover, we explore how corruption of the stromal phenotype in chronic inflammatory diseases contributes to undesired, continuous recruitment of leukocytes. Emerging complex, multicellular, multilayered (co-)culture models are now addressing the molecular circuitry involved in regulating stromal organization during inflammation. Understanding context-specific changes in pro- or anti-inflammatory agents derived from the stroma, such as IL-6 (and its cofactors), is important for the generation of therapeutic strategies that restore the balance between recruitment and clearance of the inflammatory infiltrate in chronic disease.

  15. FRET Based Quantification and Screening Technology Platform for the Interactions of Leukocyte Function-Associated Antigen-1 (LFA-1) with InterCellular Adhesion Molecule-1 (ICAM-1)

    PubMed Central

    Chakraborty, Sandeep; Núñez, David; Hu, Shih-Yang; Domingo, María Pilar; Pardo, Julian; Karmenyan, Artashes; Chiou, Arthur

    2014-01-01

    The interaction between leukocyte function-associated antigen-1(LFA-1) and intercellular adhesion molecule-1 (ICAM-1) plays a pivotal role in cellular adhesion including the extravasation and inflammatory response of leukocytes, and also in the formation of immunological synapse. However, irregular expressions of LFA-1 or ICAM-1 or both may lead to autoimmune diseases, metastasis cancer, etc. Thus, the LFA-1/ICAM-1 interaction may serve as a potential therapeutic target for the treatment of these diseases. Here, we developed one simple ‘in solution’ steady state fluorescence resonance energy transfer (FRET) technique to obtain the dissociation constant (Kd) of the interaction between LFA-1 and ICAM-1. Moreover, we developed the assay into a screening platform to identify peptides and small molecules that inhibit the LFA-1/ICAM-1 interaction. For the FRET pair, we used Alexa Fluor 488-LFA-1 conjugate as donor and Alexa Fluor 555-human recombinant ICAM-1 (D1-D2-Fc) as acceptor. From our quantitative FRET analysis, the Kd between LFA-1 and D1-D2-Fc was determined to be 17.93±1.34 nM. Both the Kd determination and screening assay were performed in a 96-well plate platform, providing the opportunity to develop it into a high-throughput assay. This is the first reported work which applies FRET based technique to determine Kd as well as classifying inhibitors of the LFA-1/ICAM-1 interaction. PMID:25032811

  16. Renal FcRn reclaims albumin but facilitates elimination of IgG.

    PubMed

    Sarav, Menaka; Wang, Ying; Hack, Bradley K; Chang, Anthony; Jensen, Mark; Bao, Lihua; Quigg, Richard J

    2009-09-01

    The widely distributed neonatal Fc receptor (FcRn) contributes to maintaining serum levels of albumin and IgG in adults. In the kidney, FcRn is expressed on the podocytes and the brush border of the proximal tubular epithelium. Here, we evaluated the role of renal FcRn in albumin and IgG metabolism. Compared with wild-type controls, FcRn(-/-) mice had a lower t((1/2)) for albumin (28.7 versus 39.9 h) and IgG (29.5 versus 66.1 h). Renal loss of albumin could account for the former, suggested by the progressive development of hypoalbuminemia in wild-type mice transplanted with FcRn-deficient kidneys. Furthermore, serum albumin levels returned to normal in FcRn(-/-) recipients of wild-type kidneys after removing the native FcRn-deficient kidneys. In contrast, renal loss could not account for the enhanced elimination of IgG in FcRn(-/-) mice. These mice had minimal urinary excretion of native and labeled IgG, which increased to wild-type levels in FcRn(-/-) recipients of a single FcRn-sufficient kidney (t((1/2)) of IgG was 21.7 h). Taken together, these data suggest that renal FcRn reclaims albumin, thereby maintaining the serum concentration of albumin, but facilitates the loss of IgG from plasma protein pools.

  17. Sialylation of IgG Fc domain impairs complement-dependent cytotoxicity

    PubMed Central

    Quast, Isaak; Keller, Christian W.; Maurer, Michael A.; Giddens, John P.; Tackenberg, Björn; Wang, Lai-Xi; Münz, Christian; Nimmerjahn, Falk; Dalakas, Marinos C.; Lünemann, Jan D.

    2015-01-01

    IgG molecules exert both pro- and antiinflammatory effector functions based on the composition of the fragment crystallizable (Fc) domain glycan. Sialylated IgG Fc domains have antiinflammatory properties that are attributed to their ability to increase the activation threshold of innate effector cells to immune complexes by stimulating the upregulation of the inhibitory Fcγ receptor IIB (FcγRIIB). Here, we report that IgG Fc sialylation of human monoclonal IgG1 molecules impairs their efficacy to induce complement-mediated cytotoxicity (CDC). Fc sialylation of a CD20-targeting antibody had no impact on antibody-dependent cellular cytotoxicity and did not change the affinity of the antibody for activating Fcγ receptors. In contrast, the presence of sialic acid abrogated the increased binding of C1q to Fc-galactosylated IgG1 and resulted in decreased levels of C3b deposition on the cell surface. Similar to monoclonal antibodies, sialic acid inhibited the increased C1q binding to galactosylated Fc fragments in human polyclonal IgG. In sera derived from patients with chronic inflammatory demyelinating polyneuropathy, an autoimmune disease of the peripheral nervous system in which humoral immune responses mediate tissue damage, induction of IgG Fc sialylation was associated with clinical disease remission. Thus, impairment of CDC represents an FcγR-independent mechanism by which Fc-sialylated glycovariants might limit proinflammatory IgG effector functions. PMID:26436649

  18. Sialylation of IgG Fc domain impairs complement-dependent cytotoxicity.

    PubMed

    Quast, Isaak; Keller, Christian W; Maurer, Michael A; Giddens, John P; Tackenberg, Björn; Wang, Lai-Xi; Münz, Christian; Nimmerjahn, Falk; Dalakas, Marinos C; Lünemann, Jan D

    2015-11-01

    IgG molecules exert both pro- and antiinflammatory effector functions based on the composition of the fragment crystallizable (Fc) domain glycan. Sialylated IgG Fc domains have antiinflammatory properties that are attributed to their ability to increase the activation threshold of innate effector cells to immune complexes by stimulating the upregulation of the inhibitory Fcγ receptor IIB (FcγRIIB). Here, we report that IgG Fc sialylation of human monoclonal IgG1 molecules impairs their efficacy to induce complement-mediated cytotoxicity (CDC). Fc sialylation of a CD20-targeting antibody had no impact on antibody-dependent cellular cytotoxicity and did not change the affinity of the antibody for activating Fcγ receptors. In contrast, the presence of sialic acid abrogated the increased binding of C1q to Fc-galactosylated IgG1 and resulted in decreased levels of C3b deposition on the cell surface. Similar to monoclonal antibodies, sialic acid inhibited the increased C1q binding to galactosylated Fc fragments in human polyclonal IgG. In sera derived from patients with chronic inflammatory demyelinating polyneuropathy, an autoimmune disease of the peripheral nervous system in which humoral immune responses mediate tissue damage, induction of IgG Fc sialylation was associated with clinical disease remission. Thus, impairment of CDC represents an FcγR-independent mechanism by which Fc-sialylated glycovariants might limit proinflammatory IgG effector functions.

  19. Mutagenesis of the rapamycin producer Streptomyces hygroscopicus FC904.

    PubMed

    Cheng, Y R; Huang, J; Qiang, H; Lin, W L; Demain, A L

    2001-11-01

    Rapamycin (RPM) is produced by Streptomyces hygroscopicus FC904 isolated from soil in Fuzhou, China. It is a triene macrolide antibiotic with potential application as an immunosuppressant and drug for human gene therapy. In an attempt to improve rapamycin production, mutation and screening of the parent culture have been carried out. Thousands of survivors were obtained after mutagenesis by NTG (3 mg/ml) and UV (30 W, 15 cm, 30 seconds) of spore suspensions. None showed improved production of RPM. We determined the susceptibility to antibiotics of S. hygroscopicus FC904 by two fold dilutions of antibiotics in oatmeal agar plates. It was found that the strain was resistant to penicillin, erythromycin, RPM, tetracycline and chloramphenicol, but susceptible to mitomycin C (MIC, 10 microg/ml) and aminoglycosides such as gentamicin (MIC, 0.1 microg/ml), kanamycin (MIC, 0.1 microg/ml) and streptomycin (MIC, 0.3 microg/ml). Protoplasts of strain FC904 were prepared after finding the best conditions for their formation. They were treated with gentamicin, erythromycin, mitomycin C and NTG. Surprisingly, gentamicin was especially effective for obtaining higher RPM-producing mutants. Mutant C14 was selected by exposing the protoplasts of the parent strain FC904 to 1 microg/ml of gentamicin at 28 degrees C for 2 hours. A higher RPM-producing mutant (C14-1) was obtained from the protoplasts of mutant C14 treated with gentamicin, and its titer was 60% higher than that of the parent strain FC904 by HPLC analysis. Another improved mutant (C14-2) was obtained from the spores of mutant C 14 treated with 1 microg/ml of gentamicin plus 2 mg/ml of NTG at 28 degrees C for 2 hours. Mutant C14-2 had a titer 124% higher than FC904. The possible mechanism for the effect of gentamicin by using protoplasts or spore suspensions will be discussed, i.e. the possibility of gentamicin being a mutagen or a selective agent. PMID:11827040

  20. The monocyte locomotion inhibitory factor produced by Entamoeba histolytica inhibits induced nitric oxide production in human leukocytes.

    PubMed

    Rico, G; Leandro, E; Rojas, S; Giménez, J A; Kretschmer, R R

    2003-07-01

    The monocyte locomotion inhibitory factor, an anti-inflammatory pentapeptide produced by Entamoeba histolytica, inhibits the in vitro production of nitric oxide induced by cytokines (INF-gamma, TNF-alpha) or PMA in human leukocytes. This can be added to the other previously reported functional effects of this factor, such as the inhibition of monocyte locomotion and the synthesis of reactive oxygen intermediates in both monocytes and neutrophils. The decreased nitric oxide production may interfere with the killing of amebas by neutrophils in the early invasive stages of amebiasis, when oxidative mechanisms are used [reactive oxygen and nitrogen intermediates either individually or synergistically via peroxynitrite (ONOO(-))], and in the advanced stages, when both non-oxidative and oxidative (including nitric oxide) mechanisms are employed by macrophages. Diminished nitric oxide production by leukocytes may also contribute to the paucity of late inflammatory components in amebic abscess of the liver and other amebic lesions.

  1. [Detection and typing for swine leukocyte antigen].

    PubMed

    Li, Hua; Luo, Huai-Rong; Zhang, Ya-Ping; Qiu, Xiang-Pin; Ye, Chun

    2004-03-01

    Traditionally the cluster of swine leukocyte antigen (SLA) was typed by serological, cytological and biochemical methods. Many special molecular typing methods have been developed with the progress of molecular biological technology, such as PCR-RFLP, PCR-SSCP , MS and DNA sequencing. Here we discussed the advantages and disadvantages of each method based on the polymorphic and conservative (from the functional aspect, such as supertype and supermotif) characteristics of SLA, and illustrated the development of typing for SLA in the future. In addition, we pointed out the editorial mistakes about the serological haplotype of SLA in reference book and emphasized that the accurate polymorphism of SLA-DQB gene must be based on the cloning sequencing. PMID:15639990

  2. Persistent vacuoles in leukocytes: familial Jordans anomaly.

    PubMed

    Ulukutlu, L; Koç, O N; Taşyürekli, M; Cullu, F; Tüzüner, N; Ulutin, O N; Oz, F; Seger, R A; Sağlamer, L

    1995-04-01

    Multiple persistent vacuoles were seen in the neutrophils, monocytes and eosinophils of a 9 year old boy and his 10 year old sister. The siblings were both asymptomatic. In the bone marrow, the cytoplasmic vacuoles were also present in the promyelocytes, myelocytes and metamyelocytes, but not in the myeloblasts and they tended to be single and large in immature cells. The cytoplasmic vacuoles did not stain with PAS, Sudan Black or Oil Red O; Sudan III positivity of the vacuoles was found only in a very small number of granulocytes. The vacuoles appeared as round and bright bodies with phase contrast microscopy. By electron microscopy, the vacuoles contained material of low electron density and had no surrounding membrane. Granulocyte functions were unimpaired. Muscle biopsy showed normal morphology. This anomalous vacuolization of the leukocytes is consistent with familial Jordans anomaly.

  3. Polymorphonuclear leukocyte kinetics in experimentally induced keratitis.

    PubMed

    Chusid, M J; Davis, S D

    1985-02-01

    The movement of polymorphonuclear leukocytes (PMNLs) into inflamed corneas was studied using a quantitative technique to measure PMNL chemotaxis in vivo. Our studies suggested that, in this model, most PMNLs enter the cornea through limbal vessels. A variety of bacterial agents, including viable bacteria, killed bacteria, culture filtrates, and endotoxin, were found to induce a significant corneal inflammatory response. Of the agents tested, viable Pseudomonas aeruginosa produced greatest inflammation. Host factors (serum, PMNLs) also induced movement of PMNLs into corneas, but only after preincubation with activating agents. Normal serum, resting PMNLs, and PMNL lysates derived from resting cells did not promote PMNL corneal ingress. These studies provide further insight into the movement of PMNLs into the inflamed cornea and information that may be of use in developing techniques to inhibit the corneal inflammatory response. PMID:3977698

  4. HA Antibody-Mediated FcγRIIIa Activity Is Both Dependent on FcR Engagement and Interactions between HA and Sialic Acids

    PubMed Central

    Cox, Freek; Kwaks, Ted; Brandenburg, Boerries; Koldijk, Martin H.; Klaren, Vincent; Smal, Bastiaan; Korse, Hans J. W. M.; Geelen, Eric; Tettero, Lisanne; Zuijdgeest, David; Stoop, Esther J. M.; Saeland, Eirikur; Vogels, Ronald; Friesen, Robert H. E.; Koudstaal, Wouter; Goudsmit, Jaap

    2016-01-01

    Interactions with receptors for the Fc region of IgG (FcγRs) have been shown to contribute to the in vivo protection against influenza A viruses provided by broadly neutralizing antibodies (bnAbs) that bind to the viral hemagglutinin (HA) stem. In particular, Fc-mediated antibody-dependent cellular cytotoxicity (ADCC) has been shown to contribute to protection by stem-binding bnAbs. Fc-mediated effector functions appear not to contribute to protection provided by strain-specific HA head-binding antibodies. We used a panel of anti-stem and anti-head influenza A and B monoclonal antibodies with identical human IgG1 Fc domains and investigated their ability to mediate ADCC-associated FcγRIIIa activation. Antibodies which do not interfere with sialic acid binding of HA can mediate FcγRIIIa activation. However, the FcγRIIIa activation was inhibited when a mutant HA, unable to bind sialic acids, was used. Antibodies which block sialic acid receptor interactions of HA interfered with FcγRIIIa activation. The inhibition of FcγRIIIa activation by HA head-binding and sialic acid receptor-blocking antibodies was confirmed in plasma samples of H5N1 vaccinated human subjects. Together, these results suggest that in addition to Fc–FcγR binding, interactions between HA and sialic acids on immune cells are required for optimal Fc-mediated effector functions by anti-HA antibodies. PMID:27746785

  5. Analytical FcRn affinity chromatography for functional characterization of monoclonal antibodies

    PubMed Central

    Schlothauer, Tilman; Rueger, Petra; Stracke, Jan Olaf; Hertenberger, Hubert; Fingas, Felix; Kling, Lothar; Emrich, Thomas; Drabner, Georg; Seeber, Stefan; Auer, Johannes; Koch, Stefan; Papadimitriou, Apollon

    2013-01-01

    The neonatal Fc receptor (FcRn) is important for the metabolic fate of IgG antibodies in vivo. Analysis of the interaction between FcRn and IgG in vitro might provide insight into the structural and functional integrity of therapeutic IgG that may affect pharmacokinetics (PK) in vivo. We developed a standardized pH gradient FcRn affinity liquid chromatography method with conditions closely resembling the physiological mechanism of interaction between IgG and FcRn. This method allows the separation of molecular IgG isoforms, degradation products and engineered molecules based on their affinity to FcRn. Human FcRn was immobilized on the column and a linear pH gradient from pH 5.5 to 8.8 was applied. FcRn chromatography was used in comparison to surface plasmon resonance to characterize different monoclonal IgG preparations, e.g., oxidized or aggregated species. Wild-type and engineered IgGs were compared in vitro by FcRn chromatography and in vivo by PK studies in huFcRn transgenic mice. Analytical FcRn chromatography allows differentiation of IgG samples and variants by peak pattern and retention time profile. The method can distinguish: 1) IgGs with different Fabs, 2) oxidized from native IgG, 3) aggregates from monomer and 4) antibodies with mutations in the Fc part from wild-type IgGs. Changes in the FcRn chromatographic behavior of mutant IgGs relative to the wild-type IgG correlate to changes in the PK profile in the FcRn transgenic mice. These results demonstrate that FcRn affinity chromatography is a useful new method for the assessment of IgG integrity. PMID:23765230

  6. Engineered antibody Fc variants with enhanced effector function.

    PubMed

    Lazar, Greg A; Dang, Wei; Karki, Sher; Vafa, Omid; Peng, Judy S; Hyun, Linus; Chan, Cheryl; Chung, Helen S; Eivazi, Araz; Yoder, Sean C; Vielmetter, Jost; Carmichael, David F; Hayes, Robert J; Dahiyat, Bassil I

    2006-03-14

    Antibody-dependent cell-mediated cytotoxicity, a key effector function for the clinical efficacy of monoclonal antibodies, is mediated primarily through a set of closely related Fcgamma receptors with both activating and inhibitory activities. By using computational design algorithms and high-throughput screening, we have engineered a series of Fc variants with optimized Fcgamma receptor affinity and specificity. The designed variants display >2 orders of magnitude enhancement of in vitro effector function, enable efficacy against cells expressing low levels of target antigen, and result in increased cytotoxicity in an in vivo preclinical model. Our engineered Fc regions offer a means for improving the next generation of therapeutic antibodies and have the potential to broaden the diversity of antigens that can be targeted for antibody-based tumor therapy.

  7. The neonatal Fc receptor does not modulate hepatitis C virus neutralization.

    PubMed

    Morel, Anthony; Passot, Christophe; Arnoult, Christophe; Dumans, Amélie; Beaumont, Elodie; Gouilleux-Gruart, Valérie; Roingeard, Philippe; Blanchard, Emmanuelle

    2015-05-01

    The neonatal Fc receptor (FcRn) is the only receptor known to be able to transport IgG across cell barriers and may therefore modulate virus infection. FcRn is expressed efficiently in hepatocytes. We therefore investigated the possible involvement of an FcRn-dependent mechanism in hepatitis C virus (HCV) neutralization. Our study, in both HCV pseudoparticles and HCV in cell-culture models, showed that FcRn was not involved in the intracellular neutralization of HCV, in contrast to the situation observed for influenza A virus.

  8. Localization of indium-111 leukocytes in noninfected neoplasms

    SciTech Connect

    Lamki, L.M.; Kasi, L.P.; Haynie, T.P.

    1988-12-01

    Indium-111-labeled autologous leukocyte studies in general carry a high sensitivity, specificity, and accuracy for the investigation of infections and abscesses. However, past studies have described sporadic cases in which In leukocytes localized in tumors. Our experience using In leukocytes for the investigation of fever of unknown origin in cancer patients, however, indicates a relatively high incidence of In leukocyte localization in noninfected neoplasms. Out of the 61 patients studied for fever of unknown origin, 21 patients (34%) manifested abnormal localization of In leukocytes in neoplasms without clinical evidence of infection. These included patients with abnormal localization in: (a) lymph nodes, (b) soft-tissue tumors, and (c) bone neoplasms. The tumors included both primary and secondary lesions, and hematologic as well as solid tumors. The mechanism of In leukocyte localization in tumors is still not completely explained. Interpretations of In leukocyte studies in cancer patients with fever should take into consideration the possibility that localization may occur in neoplastic tissue per se and does not always indicate the presence of infection.

  9. Leukocyte labeling with technetium-99m tin colloids

    SciTech Connect

    Mock, B.H.; English, D.

    1987-09-01

    Triple density gradients of metrizamide in plasma (MP) were used to characterize label distribution in human leukocyte preparations incubated with /sup 99m/Tc tin colloids. Less than 50% of the cell-associated radioactivity was specifically bound to leukocytes when heparinized blood was rotated with stannous fluoride colloid ((Tc)SFC). Labeling efficiency in leukocyte rich plasma (LRP) averaged 44%, of which greater than 90% was specifically bound to leukocytes. MP-gradient analysis also revealed that leukocyte labeling did not occur with stannous chloride colloid, nor when citrate was present during rotation with (Tc)SFC. When citrate was added after labeling to solubilize unbound (Tc)SFC, radiocolloid was removed from the leukocytes, indicating that the mechanism of (Tc)SFC labeling is adherence rather than phagocytosis. Technetium-labeled neutrophils exhibited normal in vitro chemotaxis and no lung uptake in vivo. Technetium-labeled mononuclear leukocytes, on the other hand, exhibited prolonged lung transit in vivo. Neither (Tc)SFC cell preparation showed signs of in vivo reoxidation to pertechnetate.

  10. A multi-Fc-species system for recombinant antibody production

    PubMed Central

    Moutel, Sandrine; El Marjou, Ahmed; Vielemeyer, Ole; Nizak, Clément; Benaroch, Philippe; Dübel, Stefan; Perez, Franck

    2009-01-01

    Background Genomic, transcriptomic and proteomic projects often suffer from a lack of functional validation creating a strong demand for specific and versatile antibodies. Antibody phage display represents an attractive approach to select rapidly in vitro the equivalent of monoclonal antibodies, like single chain Fv antibodies, in an inexpensive and animal free way. However, so far, recombinant antibodies have not managed to impose themselves as efficient alternatives to natural antibodies. Results We developed a series of vectors that allow one to easily fuse single chain Fv antibodies to Fc domains of immunoglobulins, improving their sensitivity and facilitating their use. This series enables the fusion of single chain Fv antibodies with human, mouse or rabbit Fc so that a given antibody is no longer restricted to a particular species. This opens up unlimited multiplexing possibilities and gives additional value to recombinant antibodies. We also show that this multi-Fc species production system can be applied to natural monoclonal antibodies cloned as single chain Fv antibodies and we converted the widely used 9E10 mouse anti-Myc-tag antibody into a human and a rabbit antibody. Conclusion Altogether, this new expression system, that brings constant quality, sensitivity and unique versatility, will be important to broaden the use of recombinant and natural monoclonal antibodies both for laboratory and diagnosis use. PMID:19245715

  11. Expression and immunohistochemical localization of the neonatal Fc receptor (FcRn) in the mammary glands of the Egyptian water buffalo.

    PubMed

    Sayed-Ahmed, Ahmed; Kassab, Mohamed; Abd-Elmaksoud, Ahmed; Elnasharty, Mohamed; El-Kirdasy, Ahmed

    2010-07-01

    Although a marginal placental transfer of maternal immunoglobulin (Ig) has been demonstrated in buffalo, the colostrum still provides the main source of immune components and nutrients to neonate buffalo calves. The neonatal Fc receptor (FcRn) transports maternal Ig across the gut wall and is involved in the transport of IgG in the mammary gland. In this study we used RT-PCR to examine the gene expression of FcRn in the mammary gland during several physiological states of the Egyptian water buffalo. The buffalo FcRn showed a high sequence homology to that of other mammalian species and especially the cow. Immunohistochemistry demonstrated positive immunolabelling of FcRn in the epithelial cells of the acini and ducts of the examined mammary gland tissue. Remarkable differences in both the cellular localization and in the intensity of FcRn immunopositivity were observed depending on the functional state of the mammary gland tissues. In late pregnancy, the FcRn immunolabelling was homogeneously distributed in the cytoplasm of the epithelial cells. In recently parturient animals, positive FcRn immunolabelling was mainly located at the luminal surface and apical cytoplasm of the mammary gland epithelium, while in dry and lactating animals, the FcRn immunolabelling was in the apical cytoplasm of the cells. The strongest FcRn immunolabelling was observed in late pregnancy and in recently parturient animals. In conclusion, the present data support the notion that FcRn might be involved in the transfer of maternal immunoglobulins and in the local defense mechanism of the mammary gland. PMID:19481783

  12. Expression and immunohistochemical localization of the neonatal Fc receptor (FcRn) in the mammary glands of the Egyptian water buffalo.

    PubMed

    Sayed-Ahmed, Ahmed; Kassab, Mohamed; Abd-Elmaksoud, Ahmed; Elnasharty, Mohamed; El-Kirdasy, Ahmed

    2010-07-01

    Although a marginal placental transfer of maternal immunoglobulin (Ig) has been demonstrated in buffalo, the colostrum still provides the main source of immune components and nutrients to neonate buffalo calves. The neonatal Fc receptor (FcRn) transports maternal Ig across the gut wall and is involved in the transport of IgG in the mammary gland. In this study we used RT-PCR to examine the gene expression of FcRn in the mammary gland during several physiological states of the Egyptian water buffalo. The buffalo FcRn showed a high sequence homology to that of other mammalian species and especially the cow. Immunohistochemistry demonstrated positive immunolabelling of FcRn in the epithelial cells of the acini and ducts of the examined mammary gland tissue. Remarkable differences in both the cellular localization and in the intensity of FcRn immunopositivity were observed depending on the functional state of the mammary gland tissues. In late pregnancy, the FcRn immunolabelling was homogeneously distributed in the cytoplasm of the epithelial cells. In recently parturient animals, positive FcRn immunolabelling was mainly located at the luminal surface and apical cytoplasm of the mammary gland epithelium, while in dry and lactating animals, the FcRn immunolabelling was in the apical cytoplasm of the cells. The strongest FcRn immunolabelling was observed in late pregnancy and in recently parturient animals. In conclusion, the present data support the notion that FcRn might be involved in the transfer of maternal immunoglobulins and in the local defense mechanism of the mammary gland.

  13. The removal of leukocytes and platelets from whole blood.

    PubMed

    Beutler, E; West, C; Blume, K G

    1976-08-01

    Various methods for the removal of leukocytes from whole blood have been compared and a new technique has been devised. This procedure consists of passing whole blood through a bed composed of microcrystalline cellulose and alpha-cellulose. The method is rapid, reliable, removes over 99.75 per cent of the leukocytes from blood, and does not seem selectively to retain reticulocytes or to release a significant proportion of leukocyte enzymes. Most of the platelets are also removed from anticoagulated blood, and platelet-free red cells can be obtained by passing defibrinated blood over the microcrystalline cellulose-alpha-cellulose bed.

  14. Shifting FcγRIIA-ITAM from activation to inhibitory configuration ameliorates arthritis

    PubMed Central

    Ben Mkaddem, Sanae; Hayem, Gilles; Jönsson, Friederike; Rossato, Elisabetta; Boedec, Erwan; Boussetta, Tarek; El Benna, Jamel; Launay, Pierre; Goujon, Jean-Michel; Benhamou, Marc; Bruhns, Pierre; Monteiro, Renato C.

    2014-01-01

    Rheumatoid arthritis–associated (RA-associated) inflammation is mediated through the interaction between RA IgG immune complexes and IgG Fc receptors on immune cells. Polymorphisms within the gene encoding the human IgG Fc receptor IIA (hFcγRIIA) are associated with an increased risk of developing RA. Within the hFcγRIIA intracytoplasmic domain, there are 2 conserved tyrosine residues arranged in a noncanonical immunoreceptor tyrosine–based activation motif (ITAM). Here, we reveal that inhibitory engagement of the hFcγRIIA ITAM either with anti-hFcγRII F(ab′)2 fragments or intravenous hIgG (IVIg) ameliorates RA-associated inflammation, and this effect was characteristic of previously described inhibitory ITAM (ITAMi) signaling for hFcαRI and hFcγRIIIA, but only involves a single tyrosine. In hFcγRIIA-expressing mice, arthritis induction was inhibited following hFcγRIIA engagement. Moreover, hFcγRIIA ITAMi-signaling reduced ROS and inflammatory cytokine production through inhibition of guanine nucleotide exchange factor VAV-1 and IL-1 receptor–associated kinase 1 (IRAK-1), respectively. ITAMi signaling was mediated by tyrosine 304 (Y304) within the hFcγRIIA ITAM, which was required for recruitment of tyrosine kinase SYK and tyrosine phosphatase SHP-1. Anti-hFcγRII F(ab′)2 treatment of inflammatory synovial cells from RA patients inhibited ROS production through induction of ITAMi signaling. These data suggest that shifting constitutive hFcγRIIA-mediated activation to ITAMi signaling could ameliorate RA-associated inflammation. PMID:25061875

  15. Polymorphisms of Immunoglobulin G Fc Receptors in Pediatric Guillain-Barré Syndrome.

    PubMed

    Mansour, Lobna A; Girgis, Marian Y; Abdulhay, Mohamed; ElEinein, Ehab I Abou; ElHawary, Rabab; Hanna, Mariam Onsy F

    2016-06-01

    Introduction Guillain-Barré syndrome (GBS) is an autoimmune peripheral neuropathy characterized by demyelination and axonal damage. Biallelic functional polymorphisms in the immunoglobulin G Fc receptors (FcγR)-FcγRIIA: H131/R131, FcγRIIIA: V158/F158, and FcγRIIIB: NA1/NA2 affect the affinity of the IgG-FcγR interaction, therefore, diseases such as GBS in which this interaction plays a critical role might be influenced by the polymorphisms. Methods We evaluated the role of FcγR polymorphisms in susceptibility to GBS in Egyptian pediatric patients and the association of the variant alleles with neurophysiological types, severity, and outcome of the disease. A total of 50 patients with GBS and 50 controls were examined for FcγR polymorphisms by allele-specific polymerase chain reaction. Results FcγRIIA H131 allele (p = < 0.0001; odds ratio [OR] = 4.78; 95% confidence interval [CI], 2.62-8.70) and FcγRIIA H/H131 genotype (p = < 0.0001 ; OR = 10.56; 95% CI, 3.59-31.06) were significantly increased in GBS patients while FcγRIIIA and FcγRIIIB allelic distributions were similar among patients and controls. The FcγR genotypes showed no association with neurophysiological types of GBS, severity or outcome of the disease. Conclusions These findings reflect that FcγRIIA H131 allele may represent a risk marker for susceptibility to GBS. PMID:27064330

  16. Acetylcholinesterase-Fc Fusion Protein (AChE-Fc): A Novel Potential Organophosphate Bioscavenger with Extended Plasma Half-Life.

    PubMed

    Noy-Porat, Tal; Cohen, Ofer; Ehrlich, Sharon; Epstein, Eyal; Alcalay, Ron; Mazor, Ohad

    2015-08-19

    Acetylcholinesterase (AChE) is the physiological target of organophosphate nerve agent compounds. Currently, the development of a formulation for prophylactic administration of cholinesterases as bioscavengers in established risk situations of exposure to nerve agents is the incentive for many efforts. While cholinesterase bioscavengers were found to be highly effective in conferring protection against nerve agent exposure in animal models, their therapeutic use is complicated by short circulatory residence time. To create a bioscavenger with prolonged plasma half-life, compatible with biotechnological production and purification, a chimeric recombinant molecule of HuAChE coupled to the Fc region of human IgG1 was designed. The novel fusion protein, expressed in cultured cells under optimized conditions, maintains its full enzymatic activity, at levels similar to those of the recombinant AChE enzyme. Thus, this novel fusion product retained its binding affinity toward BW284c5 and propidium, and its bioscavenging reactivity toward the organophosphate-AChE inhibitors sarin and VX. Furthermore, when administered to mice, AChE-Fc exhibits exceptional circulatory residence longevity (MRT of 6000 min), superior to any other known cholinesterase-based recombinant bioscavengers. Owing to its optimized pharmacokinetic performance, high reactivity toward nerve agents, and ease of production, AChE-Fc emerges as a promising next-generation organophosphate bioscavenger.

  17. Interleukin-1 receptor mRNA expression in activated bovine leukocytes in vitro.

    PubMed Central

    Yu, P W; Schuler, L A; Czuprynski, C J

    1997-01-01

    Interleukin-1 (IL-1) is a key player in inflammation and the immune response. To better understand the complex interactions of IL-1 and its receptors in inflammation, we need to investigate how type I and type II IL-1 receptors (IL-1RI and IL-1RII) are regulated by cytokines and other mediators. Using semiquantitative reverse transcriptase PCR and Northern analysis, we examined the regulation of IL-1RI and IL-1RII mRNA levels in bovine polymorphonuclear leukocytes (PMNs) (i.e., neutrophils) and peripheral blood mononuclear cells (PBMCs) in vitro. IL-1RI mRNA levels were up-regulated in PBMCs by recombinant bovine IL-1beta (rBoIL-1beta), recombinant bovine granulocyte-macrophage colony-stimulating factor (rBoGM-CSF), rBoIL-4, recombinant bovine gamma interferon (rBoIFN-gamma), and dexamethasone. IL-1RI mRNA was increased in bovine PMNs exposed to rBoGM-CSF, rBoIL-4, and dexamethasone but was down-regulated by rBoIL-1beta and rBoIFN-gamma. IL-1RII mRNA was increased in bovine PBMCs and PMNs after exposure to rBoIL-1beta, rBoGM-CSF, rBoIL-4, and dexamethasone. In contrast, rBoIFN-gamma down-regulated the expression of bovine IL-1RII mRNA in PBMCs. These findings suggest that the expression of bovine IL-1RI and IL-1RII mRNAs is regulated differently by certain soluble stimuli (e.g., IFN-gamma) in PMNs and PBMCs. PMID:9384305

  18. Technique of leukocyte harvesting and labeling: problems and perspectives

    SciTech Connect

    McAfee, J.G.; Subramanian, G.; Gagne, G.

    1984-04-01

    Mixed leukocyte suspensions obtained after gravity sedimentation of red cells and labeled with /sup 111/In lipophilic chelates are now widely used clinically for abscess localization at many medical centers. So far, labeling with /sup 111/In-oxine or tropolone has been more successful than any /sup 99/mTc method. More sophisticated approaches are available for isolation and labeling of specific leukocyte cell types, to study their migration in vivo. The most significant advances in cell harvesting include newer density gradients for isopyknic centrifugation, centrifugal elutriation, and flow cytometry. Unlike current radioactive agents which label many cell types indiscriminately, more selective ligands are being developed which bind to specific cell surface receptors. These will label certain leukocyte populations or subtypes while not reacting with others, thereby avoiding laborious separation techniques. Monoclonal antibodies against leukocyte cell-surface antigens appear particularly promising as agents for selective cell labeling.

  19. Targeting vascular and leukocyte communication in angiogenesis, inflammation and fibrosis.

    PubMed

    Kreuger, Johan; Phillipson, Mia

    2016-02-01

    Regulation of vascular permeability, recruitment of leukocytes from blood to tissue and angiogenesis are all processes that occur at the level of the microvasculature during both physiological and pathological conditions. The interplay between microvascular cells and leukocytes during inflammation, together with the emerging roles of leukocytes in the modulation of the angiogenic process, make leukocyte-vascular interactions prime targets for therapeutics to potentially treat a wide range of diseases, including pathological and dysfunctional vessel growth, chronic inflammation and fibrosis. In this Review, we discuss how the different cell types that are present in and around microvessels interact, cooperate and instruct each other, and in this context we highlight drug targets as well as emerging druggable processes that can be exploited to restore tissue homeostasis.

  20. Clinical imaging with indium-111 leukocytes: uptake in bowel infarction

    SciTech Connect

    Gray, H.W.; Cuthbert, I.; Richards, J.R.

    1981-08-01

    Leukocytes labeled with indium-111 accumulated in an area of small-bowel infarction, mimicking a paracolic abscess. Evidence of subacute bowel obstruction should alert the nuclear medicine physician to the former possibility.

  1. Membrane-type matrix metalloproteinases: key mediators of leukocyte function.

    PubMed

    Marco, Marta; Fortin, Carl; Fulop, Tamas

    2013-08-01

    Leukocytes are major cellular effectors of the immune response. To accomplish this task, these cells display a vast arsenal of proteinases, among which, members of the MMP family are especially important. Leukocytes express several members of the MMP family, including secreted- and membrane-anchored MT- MMPs, which synergistically orchestrate an appropriate proteolytic reaction that ultimately modulates immunological responses. The MT-MMP subfamily comprises TM- and GPI-anchored proteinases, which are targeted to well-defined membrane microdomains and exhibit different substrate specificities. Whereas much information exists on the biological roles of secreted MMPs in leukocytes, the roles of MT-MMPs remain relatively obscure. This review summarizes the current knowledge on the expression of MT-MMPs in leukocyte and their contribution to the immune responses and to pathological conditions. PMID:23695309

  2. Carp thrombocyte phagocytosis requires activation factors secreted from other leukocytes.

    PubMed

    Nagasawa, Takahiro; Somamoto, Tomonori; Nakao, Miki

    2015-10-01

    Thrombocytes are nucleated blood cells in non-mammalian vertebrates, which were recently focused on not only as hemostatic cells but also as immune cells with potent phagocytic activities. We have analyzed the phagocytic activation mechanisms in common carp (Cyprinus carpio) thrombocytes. MACS-sorted mAb(+) thrombocytes showed no phagocytic activity even in the presence of several stimulants. However, remixing these thrombocytes with other anti-thrombocyte mAb(-) leukocyte populations restored their phagocytic activities, indicating that carp thrombocyte phagocytosis requires an appropriate exogenous stimulation. Culture supernatant from anti-thrombocyte mAb(-) leukocytes harvested after PMA or LPS stimulation, but not culture supernatant from unstimulated leukocytes, could activate thrombocyte phagocytosis. This proposed mechanism of thrombocyte phagocytosis activation involving soluble factors produced by activated leukocytes suggests that thrombocyte activation is restricted to areas proximal to injured tissues, ensuring suppression of excessive thrombocyte activation and a balance between inflammation and tissue repair.

  3. Influence of Magnetite Nanoparticles on Human Leukocyte Activity

    NASA Astrophysics Data System (ADS)

    Džarová, Anežka; Dubničková, Martina; Závišová, Vlasta; Koneracká, Martina; Kopčanský, Peter; Gojzewski, Hubert; Timko, Milan

    2010-12-01

    Chemically synthesized magnetite particles coated by sodium oleate and PEG (MNP), and magnetosomes (MS) influence the process of phagocytosis and the metabolic activity (lysozyme and peroxidase activity) in leukocytes. Lysozyme activity is oxygen-independent liquidation mechanisms of engulfed microorganism, peroxidase activity is an oxygen-dependent mechanism. Both tested types of nanoparticles lysed leukocyte cells during incubation. MNP at concentrations of 10 and 20 μg/mL lysed almost all leukocytes and their cell viability was in the 14±0.05% range. On the other hand MS begin to influence leukocytes activity at the concentration of 1 μg/ml and this influence grows with increasing concentration up to 20 μg/ml. MS are more suitable for biological applications than MNP which are more aggressive material than MS. MS should not be used above 10 μg/mL.

  4. Osteomyelitis complicating fracture: pitfalls of /sup 111/In leukocyte scintigraphy

    SciTech Connect

    Kim, E.E.; Pjura, G.A.; Lowry, P.A.; Gobuty, A.H.; Traina, J.F.

    1987-05-01

    /sup 111/In-labeled leukocyte imaging has shown greater accuracy and specificity than alternative noninvasive methods in the detection of uncomplicated osteomyelitis. Forty patients with suspected osteomyelitis complicating fractures (with and without surgical intervention) were evaluated with /sup 111/In-labeled leukocytes. All five patients with intense focal uptake, but only one of 13 with no uptake, had active osteomyelitis. However, mild to moderate /sup 111/In leukocyte uptake, observed in 22 cases, indicated the presence of osteomyelitis in only four of these; the other false-positive results were observed in noninfected callus formation, heterotopic bone formation, myositis ossificans, and sickle-cell disease. These results suggest that /sup 111/In-labeled leukocyte imaging is useful for the evaluation of suspected osteomyelitis complicating fracture but must be used in conjunction with clinical and radiographic correlation to avoid false-positive results.

  5. Association of leukocyte telomere length in peripheral blood leukocytes with endometrial cancer risk in Caucasian Americans.

    PubMed

    Sun, Yuhui; Zhang, Liren; Zhao, Lina; Wu, Xifeng; Gu, Jian

    2015-11-01

    Telomeres are the protective structure at the ends of each chromosome and play an important role in maintaining genomic integrity. Interindividual variation of telomere length in peripheral blood leukocytes has been associated with the risks of developing many human diseases including several cancers. The association between leukocyte telomere length (LTL) and endometrial cancer risk is still inconsistent. Using a case-control study of endometrial cancer patients (n = 139) and control subjects (n = 139) in a Caucasian population, we assessed the association of relative LTL with the risk of endometrial cancer. We calculated odds ratios and 95% confidence intervals using multivariate logistic regression. We also determined the joint effects of LTL with established risk factors of endometrial cancer. The normalized LTL was significantly longer in endometrial cancer cases (median, 0.93; range, 0.19-1.62) than in controls (median, 0.70; range, 0.03-2.14) (P < 0.001). When individuals were dichotomized into long and short groups based on the median LTL value in the controls, individuals with long LTL had a significantly increased risk of endometrial cancer (adjusted OR, 3.84; 95%CI, 2.16-6.85; P < 0.001) compared to those with short LTL. When individuals were categorized into three groups or four groups according to tertile or quartile LTL value in the controls, there was a significant dose-response association between LTL and the risk of endometrial cancer (P < 0.001). Joint effects between LTL and smoking status, body mass index and a history of hypertension or diabetes in elevating endometrial cancer risk were observed. Long telomere length in peripheral blood leukocytes is associated with a significantly increased risk of endometrial cancer.

  6. Comparison of Human Neonatal and Adult Blood Leukocyte Subset Composition Phenotypes.

    PubMed

    Prabhu, Savit B; Rathore, Deepak K; Nair, Deepa; Chaudhary, Anita; Raza, Saimah; Kanodia, Parna; Sopory, Shailaja; George, Anna; Rath, Satyajit; Bal, Vineeta; Tripathi, Reva; Ramji, Siddharth; Batra, Aruna; Aggarwal, Kailash C; Chellani, Harish K; Arya, Sugandha; Agarwal, Nidhi; Mehta, Umesh; Natchu, Uma Chandra Mouli; Wadhwa, Nitya; Bhatnagar, Shinjini

    2016-01-01

    The human peripheral leukocyte subset composition depends on genotype variation and pre-natal and post-natal environmental influence diversity. We quantified this composition in adults and neonates, and compared the median values and dispersal ranges of various subsets in them. We confirmed higher frequencies of monocytes and regulatory T cells (Tregs), similar frequencies of neutrophils, and lower frequencies of CD8 T cells, NKT cells, B1 B cells and gamma-delta T cells in neonatal umbilical cord blood. Unlike previous reports, we found higher frequencies of eosinophils and B cells, higher CD4:CD8 ratios, lower frequencies of T cells and iNKT cells, and similar frequencies of CD4 T cells and NK cells in neonates. We characterized monocyte subsets and dendritic cell (DC) subsets in far greater detail than previously reported, using recently described surface markers and gating strategies and observed that neonates had lower frequencies of patrolling monocytes and lower myeloid dendritic cell (mDC):plasmacytoid DC (pDC) ratios. Our data contribute to South Asian reference values for these parameters. We found that dispersal ranges differ between different leukocyte subsets, suggesting differential determination of variation. Further, some subsets were more dispersed in adults than in neonates suggesting influences of postnatal sources of variation, while some show the opposite pattern suggesting influences of developmental process variation. Together, these data and analyses provide interesting biological possibilities for future exploration. PMID:27610624

  7. Comparison of Human Neonatal and Adult Blood Leukocyte Subset Composition Phenotypes

    PubMed Central

    Rathore, Deepak K.; Nair, Deepa; Chaudhary, Anita; Raza, Saimah; Kanodia, Parna; Sopory, Shailaja; George, Anna; Rath, Satyajit; Bal, Vineeta; Tripathi, Reva; Ramji, Siddharth; Batra, Aruna; Aggarwal, Kailash C.; Chellani, Harish K.; Arya, Sugandha; Agarwal, Nidhi; Mehta, Umesh; Natchu, Uma Chandra Mouli; Wadhwa, Nitya; Bhatnagar, Shinjini

    2016-01-01

    The human peripheral leukocyte subset composition depends on genotype variation and pre-natal and post-natal environmental influence diversity. We quantified this composition in adults and neonates, and compared the median values and dispersal ranges of various subsets in them. We confirmed higher frequencies of monocytes and regulatory T cells (Tregs), similar frequencies of neutrophils, and lower frequencies of CD8 T cells, NKT cells, B1 B cells and gamma-delta T cells in neonatal umbilical cord blood. Unlike previous reports, we found higher frequencies of eosinophils and B cells, higher CD4:CD8 ratios, lower frequencies of T cells and iNKT cells, and similar frequencies of CD4 T cells and NK cells in neonates. We characterized monocyte subsets and dendritic cell (DC) subsets in far greater detail than previously reported, using recently described surface markers and gating strategies and observed that neonates had lower frequencies of patrolling monocytes and lower myeloid dendritic cell (mDC):plasmacytoid DC (pDC) ratios. Our data contribute to South Asian reference values for these parameters. We found that dispersal ranges differ between different leukocyte subsets, suggesting differential determination of variation. Further, some subsets were more dispersed in adults than in neonates suggesting influences of postnatal sources of variation, while some show the opposite pattern suggesting influences of developmental process variation. Together, these data and analyses provide interesting biological possibilities for future exploration. PMID:27610624

  8. Neutrophil Leukocyte: Combustive Microbicidal Action and Chemiluminescence.

    PubMed

    Allen, Robert C

    2015-01-01

    Neutrophil leukocytes protect against a varied and complex array of microbes by providing microbicidal action that is simple, potent, and focused. Neutrophils provide such action via redox reactions that change the frontier orbitals of oxygen (O2) facilitating combustion. The spin conservation rules define the symmetry barrier that prevents direct reaction of diradical O2 with nonradical molecules, explaining why combustion is not spontaneous. In burning, the spin barrier is overcome when energy causes homolytic bond cleavage producing radicals capable of reacting with diradical O2 to yield oxygenated radical products that further participate in reactive propagation. Neutrophil mediated combustion is by a different pathway. Changing the spin quantum state of O2 removes the symmetry restriction to reaction. Electronically excited singlet molecular oxygen ((1)O2(*)) is a potent electrophilic reactant with a finite lifetime that restricts its radius of reactivity and focuses combustive action on the target microbe. The resulting exergonic dioxygenation reactions produce electronically excited carbonyls that relax by light emission, that is, chemiluminescence. This overview of neutrophil combustive microbicidal action takes the perspectives of spin conservation and bosonic-fermionic frontier orbital considerations. The necessary principles of particle physics and quantum mechanics are developed and integrated into a fundamental explanation of neutrophil microbicidal metabolism.

  9. Chemotactic peptide receptor modulation in polymorphonuclear leukocytes

    PubMed Central

    1980-01-01

    The binding of the chemotactic peptide N- formylnorleucylleucylphenylalanine (FNLLP) to its receptor on rabbit polymorphonuclear leukocytes (PMNs) modulates the number of available peptide receptors. Incubation with FNLLP decreases subsequent binding capacity, a phenomenon that has been termed receptor down regulation. Down regulation of the chemotactic peptide receptor is concentration dependent in both the rate and extent of receptor loss. The dose response parallels that of FNLLP binding to the recptor. The time- course is rapid; even at concentrations of FNLLP as low as 3 x 10(-9) M, the new equilibrium concentration of receptors is reached within 15 min. Down regulation is temperature dependent, but does occur even at 4 degrees C. Concomitant with down regulation, some of the peptide becomes irreversibly cell associated. At 4 degrees C, there is a small accumulation of nondissociable peptide that rapidly reaches a plateau. At higher temperatures, accumulation of nondissociable peptide continues after the rceptor number has reached equilibrium, and the amount accumulated can exceed the initial number of receptors by as much as 300%. The dose response of peptide uptake at 37 degrees C reflects that of binding, suggesting that it is receptor mediated. This uptake may occur via a pinocytosis mechanism. Although PMNs have not been considered to be pinocytic, the addition of FNLLP causes a fourfold stimulation of the rate of pinocytosis as measured by the uptake of [3H]sucrose. PMID:7391138

  10. Neutrophil Leukocyte: Combustive Microbicidal Action and Chemiluminescence

    PubMed Central

    Allen, Robert C.

    2015-01-01

    Neutrophil leukocytes protect against a varied and complex array of microbes by providing microbicidal action that is simple, potent, and focused. Neutrophils provide such action via redox reactions that change the frontier orbitals of oxygen (O2) facilitating combustion. The spin conservation rules define the symmetry barrier that prevents direct reaction of diradical O2 with nonradical molecules, explaining why combustion is not spontaneous. In burning, the spin barrier is overcome when energy causes homolytic bond cleavage producing radicals capable of reacting with diradical O2 to yield oxygenated radical products that further participate in reactive propagation. Neutrophil mediated combustion is by a different pathway. Changing the spin quantum state of O2 removes the symmetry restriction to reaction. Electronically excited singlet molecular oxygen (1O2*) is a potent electrophilic reactant with a finite lifetime that restricts its radius of reactivity and focuses combustive action on the target microbe. The resulting exergonic dioxygenation reactions produce electronically excited carbonyls that relax by light emission, that is, chemiluminescence. This overview of neutrophil combustive microbicidal action takes the perspectives of spin conservation and bosonic-fermionic frontier orbital considerations. The necessary principles of particle physics and quantum mechanics are developed and integrated into a fundamental explanation of neutrophil microbicidal metabolism. PMID:26783542

  11. Impact of IgG2 high molecular weight species on neonatal Fc receptor binding assays.

    PubMed

    Zhang, Yuling; Mathur, Abhishek; Maher, Gwen; Arroll, Thomas; Bailey, Robert

    2015-11-15

    A cell-based assay and a solution neonatal Fc receptor (FcRn) binding assay were implemented for the characterization of an IgG2 antibody after observation that different product lots exhibited unexpected differences in FcRn binding in the cell-based format with membrane-bound FcRn. The experiments described here suggest that the apparent differences observed in the FcRn binding across different product lots in the cell-based format can be attributed to the different levels of the higher order high molecular weight species (HMWs) in them. A strong correlation between FcRn binding in the cell-based format and the percentage (%) higher order HMWs suggests that small amounts (∼0.1%) of the latter could cause the enhanced apparent FcRn binding (% relative binding ranging from 50 to 100%) in the format. However, when the binding was assessed with recombinant FcRn in soluble form, avidity effects were minimal and the assay format exhibited less sensitivity toward the differences in higher order HMWs levels across product lots. In conclusion, a solution-based assay may be a more appropriate assay to assess FcRn binding of the dominant species of an Fc-fusion protein or monoclonal antibody if minor differences in product variants such as higher order HMWs are shown to affect the binding significantly.

  12. Natural cytotoxic activity in multiple sclerosis patients: defects in IL-2/interferon gamma-regulatory circuit.

    PubMed

    Braakman, E; van Tunen, A; Meager, A; Lucas, C J

    1986-11-01

    In order to determine the factors underlying the impaired natural cytotoxic (NC) activity in multiple sclerosis (MS) patients, we have analysed the interleukin 2 (IL-2)-interferon gamma-(IFN gamma)-NC activity regulatory circuit in 40 MS patients and 40 matched healthy controls. Exogenous recombinant IFN gamma (rIFN gamma) enhanced NC activity in peripheral blood lymphocytes (PBL) derived from MS patients and controls equally well. In contrast, PBL from MS patients showed a significantly lower increase of NC activity in response to IL-2 than healthy controls. This defect in responsiveness was independent of the dose of IL-2. Even at the highest dose of rIL-2 (1000 U/ml), MS patients showed a decreased response. PBL from MS patients required a 2 to 10 times higher dose of IL-2 to reach NC activity levels comparable to controls. In healthy individuals IL-2 can act upon both Fc gamma R+ and Fc gamma R- NC precursor cells. The decreased responsiveness to IL-2 is not confined to one subpopulation of IL-2-responsive precursor cells because depletion of Fc gamma R+ cells before culture in the presence of IL-2 revealed no significant differences in the contribution of Fc gamma R+ precursor cells to the IL-2 enhanced NC activity between MS patients and controls. Also the number of IL-2-responsive precursor cells appeared to be normal since the number of Fc gamma R+ cells in MS patients and controls was comparable. PBL from MS patients produced significantly lower amounts of IFN gamma upon stimulation with IL-2. Analysis of the different parameters of the regulatory circuit at the population level showed, both for patients and controls, a significant correlation between IFN gamma production and increase of NC activity induced by IL-2. Also the endogenous NC activity and IFN gamma production, both in patients and controls, were correlated. At the individual level, defects in NC activity could not be linked to another parameter of the regulatory circuit.

  13. Physiological levels of testosterone kill salmonid leukocytes in vitro

    USGS Publications Warehouse

    Slater, C.H.; Schreck, C.B.

    1997-01-01

    Adult spring chinook salmon (Oncorhynchus tshawytscha) elaborate high plasma concentrations of testosterone during sexual maturation, and these levels of testosterone have been shown to reduce the salmonid immune response in vitro. Our search for the mechanism of testosterone's immunosuppressive action has led to the characterization of an androgen receptor in salmonid leukocytes. In the present study we examined the specific effects that testosterone had on salmonid leukocytes. Direct counts of viable leukocytes after incubation with and without physiological levels of testosterone demonstrate a significant loss of leukocytes in cultures exposed to testosterone. At least 5 days of contact with testosterone was required to produce significant immunosuppression and addition of a 'conditioned media' (supernatant from proliferating lymphocytes not exposed to testosterone) did not reverse the immunosuppressive effects of testosterone. These data lead us to conclude that testosterone may exert its immunosuppressive effects by direct action on salmonid leukocytes, through the androgen receptor described, and that this action leads to the death of a significant number of these leukocytes.

  14. Leukocyte lipid bodies - biogenesis and functions in inflammation

    PubMed Central

    Bozza, Patricia T.; Magalhães, Kelly G.; Weller, Peter F.

    2009-01-01

    Lipid body accumulation within leukocytes is a common feature in both clinical and experimental infectious, neoplasic and other inflammatory conditions. Here, we will review the contemporary evidence related to the biogenesis and structure of leukocyte lipid bodies (also known as lipid droplets) as inflammatory organelles. Studies of leukocyte lipid bodies are providing functional, ultrastructural and protein compositional evidences that lipid bodies are not solely storage depots of neutral lipid. Over the past years substantial progresses have been made to demonstrate that lipid body biogenesis is a highly regulated process, that culminate in the compartmentalization of a specific set of proteins and lipids, that place leukocyte lipid bodies as inducible cytoplasmic organelles with roles in cell signaling and activation, regulation of lipid metabolism, membrane trafficking and control of the synthesis and secretion of inflammatory mediators. Pertinent to the roles of lipid bodies in inflammation and cell signaling, enzymes involved in eicosanoid synthesis are localized at lipid bodies and lipid bodies are sites for eicosanoid generation. Collectively, lipid bodies in leukocytes are emerging as critical regulators of different inflammatory diseases, key markers of leukocyte activation and attractive targets for novel anti-inflammatory therapies. PMID:19416659

  15. Binding of Pasteurella haemolytica leukotoxin to bovine leukocytes.

    PubMed Central

    Brown, J F; Leite, F; Czuprynski, C J

    1997-01-01

    Pasteurella haemolytica is the principal bacterial pathogen in the bovine respiratory disease complex. This organism produces an exotoxin (referred to as leukotoxin) during logarithmic-phase growth that is a potent leukocyte-modulating agent. At low concentrations, it activates neutrophils and mononuclear phagocytes to release inflammatory mediators, while at the same time making these cells destined to undergo apoptotic cell death. At higher concentrations, the toxin causes rapid swelling and loss of cell viability. In this study, we demonstrated that toxin binding can be directly evaluated by flow cytometry with biologically active biotinylated leukotoxin. Leukotoxin binding was blocked by the addition of a neutralizing anti-leukotoxin monoclonal antibody and was not detected when bovine leukocytes were incubated with culture filtrates from a mutant strain of P. haemolytica that does not produce biologically active leukotoxin. In addition, treatment of bovine leukocytes with protease K eliminated subsequent binding of leukotoxin, suggesting that there is a protein on the leukocyte surface that is either a leukotoxin binding site or is required for stabilization of leukotoxin binding. We did not detect binding of biotinylated leukotoxin to porcine or human leukocytes, which have been reported previously to be resistant to the lytic effects of the leukotoxin. These findings suggest that there may be a specific binding site for P. haemolytica leukotoxin on bovine but not on porcine or human leukocytes and that it might be involved in the activation and lytic activities of the leukotoxin. PMID:9284143

  16. C-type natriuretic peptide inhibits leukocyte recruitment and platelet-leukocyte interactions via suppression of P-selectin expression

    NASA Astrophysics Data System (ADS)

    Scotland, Ramona S.; Cohen, Marc; Foster, Paul; Lovell, Matthew; Mathur, Anthony; Ahluwalia, Amrita; Hobbs, Adrian J.

    2005-10-01

    The multifaceted process of immune cell recruitment to sites of tissue injury is key to the development of an inflammatory response and involved in the pathogenesis of numerous cardiovascular disorders. We recently identified C-type natriuretic peptide (CNP) as an important endothelium-derived mediator that regulates vascular tone and protects against myocardial ischemia/reperfusion injury. Herein, we investigated whether CNP inhibits leukocyte recruitment and platelet aggregation and thereby exerts a potential antiinflammatory influence on the blood vessel wall. We assessed the effects of CNP on leukocyte-endothelial cell interactions in mouse mesenteric postcapillary venules in vivo in animals with high basal leukocyte activation (endothelial nitric oxide synthase knockout mice, eNOS-/-) or under acute inflammatory conditions (induced by interleukin-1 or histamine). CNP suppressed basal leukocyte rolling in eNOS-/- mice in a rapid, reversible, and concentration-dependent manner. These effects of CNP were mimicked by the selective natriuretic peptide receptor-C agonist cANF4-23. CNP also suppressed leukocyte rolling induced by IL-1 or histamine, inhibited platelet-leukocyte interactions, and prevented thrombin-induced platelet aggregation of human blood. Furthermore, analysis of human umbilical vein endothelial cells, leukocytes, and platelets revealed that CNP selectively attenuates expression of P-selectin. Thus, CNP is a modulator of acute inflammation in the blood vessel wall characterized by leukocyte and platelet activation. These antiinflammatory effects appear to be mediated, at least in part, via suppression of P-selectin expression. These observations suggest that endothelial CNP might maintain an anti-atherogenic influence on the blood vessel wall and represent a target for therapeutic intervention in inflammatory cardiovascular disorders. endothelium | natriuretic peptide receptor type C | atherosclerosis | thrombosis

  17. Internalization of Leishmania mexicana complex amastigotes via the Fc receptor is required to sustain infection in murine cutaneous leishmaniasis.

    PubMed

    Kima, P E; Constant, S L; Hannum, L; Colmenares, M; Lee, K S; Haberman, A M; Shlomchik, M J; McMahon-Pratt, D

    2000-03-20

    We show here that maintenance of Leishmania infections with Leishmania mexicana complex parasites (Leishmania amazonensis and Leishmania pifanoi) is impaired in the absence of circulating antibody. In these studies, we used mice genetically altered to contain no circulating antibody, with and without functional B cells. This experimental design allowed us to rule out a critical role for B cell antigen presentation in Leishmania pathogenesis. In addition, we show that mice lacking the common gamma chain of Fc receptors (FcgammaRI, FcepsilonRI, and FcgammaRIII) are similarly refractory to infection with these parasites. These observations establish a critical role for antibody in the pathogenesis associated with infection by members of the L. mexicana complex.

  18. The filterability of leukocytes in undiluted blood.

    PubMed

    Cook, A M; Evans, S A; Jones, J G

    1998-01-01

    A filtrometer is described for measuring the flow of fluids through microfilters. The flow of Newtonian fluids through the filters can be predicted from the diameter, length and number of pores. There are no physical artefacts such as turbulent flow or a significant lag period before steady-state flow is achieved. The instrument has been used as a viscometer and has been used to record and analyse the flow of undiluted blood through 5 microns polycarbonate filters. The calculated viscosity of Newtonian fluids agrees well with those measured by a more conventional viscometer (Ostwald). Flow profiles of blood have been analysed to give both the numbers and the flow properties of a small population of slow leukocytes which equate numerically with the monocytes. They are subdivided into three distinct sub-populations, according to their rheological properties, and these are termed SL1, SL2 and PB. The concentration of these cells, in blood, are 0.12 +/- 0.02 x 10(6) ml-1, 0.11 +/- 0.02 x 10(6) ml-1, 0.09 +/- 0.02 x 10(6) ml-1 in young females aged about 25 years. The transit time of these cells, through 5 microns pores, is 34.8 +/- 1.4 s, 147.5 +/- 2.5 s and > 300 s, respectively. Analysis of blood from older men (53-79 years) gives essentially the same results although the concentration of SL1 is slightly higher at 0.19 +/- 0.09 x 10(6) ml-1. PMID:10193484

  19. Targeting FcRn for therapy: from live cell imaging to in vivo studies in mice.

    PubMed

    Ward, E Sally; Velmurugan, Ramraj; Ober, Raimund J

    2014-08-01

    The role of FcRn in regulating antibody levels and transport in the body is well documented. The use of fluorescence microscopy to investigate the subcellular trafficking behavior of FcRn and its IgG ligand has led to insight into the function of this receptor, including the identification of new intracellular pathways. The inhibition of FcRn using engineered antibodies that bind to this receptor with increased affinity through their Fc region can be exploited to treat antibody mediated autoimmunity. The efficacy of this approach in mouse models of arthritis and multiple sclerosis has been demonstrated. Finally, the cross-species difference between mouse and man for FcRn-IgG interactions needs to be considered when engineering antibodies for improved activities in FcRn-mediated functions.

  20. The role of Fc–FcγR interactions in IgG-mediated microbial neutralization

    PubMed Central

    Bournazos, Stylianos; DiLillo, David J.

    2015-01-01

    Antibodies are bifunctional molecules, containing a variable Fab domain that mediates binding specificity and a constant Fc domain that bridges antibody-coated targets with FcγR-expressing cells that mediate effector functions. Although traditional mechanisms of antibody-mediated neutralization of microbes have been largely thought to result from Fab–antigen interactions, recent studies suggest that recruitment of FcγR-expressing effector cells by antibodies is a major in vivo mechanism of antibody-mediated protection from infection. In this article, we review FcγR biology, compare mammalian FcγR families, and summarize recent evidence demonstrating the crucial role that Fc–FcγR interactions play during in vivo protection from infection. PMID:26282878

  1. Inhibition of Corneal Neovascularization by Subconjunctival Injection of Fc-Endostatin, a Novel Inhibitor of Angiogenesis

    PubMed Central

    Yoshida, Junko; Wicks, Robert T.; Zambrano, Andrea I.; Tyler, Betty M.; Javaherian, Kashi; Grossman, Rachel; Daoud, Yassine J.; Gehlbach, Peter; Brem, Henry; Stark, Walter J.

    2015-01-01

    We assessed the antiangiogenic effects of subconjunctival injection of Fc-endostatin (FcE) using a human vascular endothelial growth factor-induced rabbit corneal neovascularization model. Angiogenesis was induced in rabbit corneas through intrastromal implantations of VEGF polymer implanted 2 mm from the limbus. NZW rabbits were separated into groups receiving twice weekly subconjunctival injections of either saline; 25 mg/mL bevacizumab; 2 mg/mL FcE; or 20 mg/mL FcE. Corneas were digitally imaged at 5 time points. An angiogenesis index (AI) was calculated (vessel length (mm) × vessel number score) for each observation. All treatment groups showed a significant decrease in the vessel length and AI compared to saline on all observation days (P < 0.001). By day 15, FcE 2 inhibited angiogenesis significantly better than FcE 20 (P < 0.01). There was no significant difference between FcE 2 and BV, although the values trended towards significantly increased inhibition by BV. BV was a significantly better inhibitor than FcE 20 by day 8 (P < 0.01). FcE was safe and significantly inhibited new vessel growth in a rabbit corneal neovascularization model. Lower concentration FcE 2 exhibited better inhibition than FcE 20, consistent with previous FcE studies referencing a biphasic dose-response curve. Additional studies are necessary to further elucidate the efficacy and clinical potential of this novel angiogenesis inhibitor. PMID:26491546

  2. 40 CFR Table 25 to Subpart G of... - Effective Column Diameter (Fc)

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 9 2011-07-01 2011-07-01 false Effective Column Diameter (Fc) 25 Table..., Table 25 Table 25 to Subpart G of Part 63—Effective Column Diameter (Fc) Column type Fc (feet) 9-inch by 7-inch built-up columns 1.1 8-inch-diameter pipe columns 0.7 No construction details known 1.0...

  3. Heparan sulphate as a regulator of leukocyte recruitment in inflammation.

    PubMed

    Kumar, Archana V; Katakam, Sampath K; Urbanowitz, Ann-Kathrin; Gotte, Martin

    2015-01-01

    A key event in inflammatory disease is the transendothelial recruitment of leukocytes from the circulation to the site of inflammation. Intense research in the past decades indicates that the polyanionic carbohydrate heparan sulphate (HS) modulates multiple steps in the leukocyte recruitment cascade. Leukocyte recruitment is initiated by endothelial cell activation and presentation of chemokines to rolling leukocytes, which, via integrin activation, results in adhesion and diapedesis through the vessel wall. Heparan sulfate proteoglycans (HSPGs) immobilize the chemokines on the luminal endothelial cells, rendering them more robust against mechanical or hydrodynamic perturbations. During inflammation, endothelial HSPGs serve as ligands to L-selectin on leukocytes, transport chemokines in a basolateral to apical direction across the endothelium, and present chemokines at the luminal surface of the endothelium to circulating cells. HSPGs also promote chemokine oligomerization, which influences chemokine receptor signaling. Furthermore, proteoglycans of the syndecan family are involved in modulating integrin-mediated tight adhesion of leukocytes to the endothelium. Creation of a chemokine gradient by a localized chemokine release influences the speed of leukocyte recruitment from the blood to the tissue by attracting crawling neutrophils to optimal sites for transmigration. The directionality of intraluminal crawling is thought to be influenced by both mechanotactic and haptotactic signals, which are modulated by HS-dependent signaling processes. Finally, diapedesis is influenced by HS regarding transendothelial chemokine gradient formation and integrin- CAM interactions, and further enhanced by heparanase-mediated degradation of the endothelial basement membrane. Overall, the multifunctional role of HS in inflammation marks it as a potential target of glycan-centered therapeutic approaches.

  4. The novel multispecies Fc-specific Pseudomonas exotoxin A fusion protein α-Fc-ETA' enables screening of antibodies for immunotoxin development.

    PubMed

    Klausz, Katja; Kellner, Christian; Derer, Stefanie; Valerius, Thomas; Staudinger, Matthias; Burger, Renate; Gramatzki, Martin; Peipp, Matthias

    2015-03-01

    Immunoconjugates that deliver cytotoxic payloads to cancer cells represent a promising class of therapeutic agents which are intensively investigated in various clinical applications. Prerequisites for the generation of effective immunoconjugates are antibodies which efficiently deliver the respective cytotoxic payload. To facilitate the selection of human or mouse antibodies that display favorable characteristics as immunotoxins, we developed a novel Pseudomonas exotoxin A (ETA)-based screening protein. The α-Fc-ETA' consists of a multispecies-specific Fc-binding domain antibody genetically fused to a truncated ETA version (ETA'). α-Fc-ETA' non-covalently bound to human and mouse antibodies but did not form immune complexes with bovine immunoglobulins. In combination with antibodies harboring human or mouse Fc domains α-Fc-ETA' inhibited proliferation of antigen-expressing tumor cells. The cytotoxic effects were strictly antibody dependent and were observed with low α-Fc-ETA' concentrations. Mouse antibodies directed against CD7 and CD317/HM1.24 that previously had been used for the generation of functional recombinant immunotoxins, also showed activity in combination with α-Fc-ETA' by inhibiting growth of antigen-positive myeloma and leukemia cell lines. In contrast, α-kappa-ETA', a similarly designed human kappa light chain-specific fusion protein, was only specifically active in combination with antibodies containing a human kappa light chain. Thus, the novel α-Fc-ETA' fusion protein is broadly applicable in screening antibodies and Fc-containing antibody derivatives from different species to select for candidates with favorable characteristics for immunotoxin development.

  5. Analysis of the Effects of the Bruton's tyrosine kinase (Btk) Inhibitor Ibrutinib on Monocyte Fcγ Receptor (FcγR) Function.

    PubMed

    Ren, Li; Campbell, Amanda; Fang, Huiqing; Gautam, Shalini; Elavazhagan, Saranya; Fatehchand, Kavin; Mehta, Payal; Stiff, Andrew; Reader, Brenda F; Mo, Xiaokui; Byrd, John C; Carson, William E; Butchar, Jonathan P; Tridandapani, Susheela

    2016-02-01

    The irreversible Bruton's tyrosine kinase (Btk) inhibitor ibrutinib has shown efficacy against B-cell tumors such as chronic lymphocytic leukemia and B-cell non-Hodgkin lymphoma. Fcγ receptors (FcγR) on immune cells such as macrophages play an important role in tumor-specific antibody-mediated immune responses, but many such responses involve Btk. Here we tested the effects of ibrutinib on FcγR-mediated activities in monocytes. We found that ibrutinib did not affect monocyte FcγR-mediated phagocytosis, even at concentrations higher than those achieved physiologically, but suppressed FcγR-mediated cytokine production. We confirmed these findings in macrophages from Xid mice in which Btk signaling is defective. Because calcium flux is a major event downstream of Btk, we tested whether it was involved in phagocytosis. The results showed that blocking intracellular calcium flux decreased FcγR-mediated cytokine production but not phagocytosis. To verify this, we measured activation of the GTPase Rac, which is responsible for actin polymerization. Results showed that ibrutinib did not inhibit Rac activation, nor did the calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester). We next asked whether the effect of ibrutinib on monocyte FcγR-mediated cytokine production could be rescued by IFNγ priming because NK cells produce IFNγ in response to antibody therapy. Pretreatment of monocytes with IFNγ abrogated the effects of ibrutinib on FcγR-mediated cytokine production, suggesting that IFNγ priming could overcome this Btk inhibition. Furthermore, in monocyte-natural killer cell co-cultures, ibrutinib did not inhibit FcγR-mediated cytokine production despite doing so in single cultures. These results suggest that combining ibrutinib with monoclonal antibody therapy could enhance chronic lymphocytic leukemia cell killing without affecting macrophage effector function. PMID:26627823

  6. Defect of Fc receptors and phenotypical changes in sinusoidal endothelial cells in human liver cirrhosis.

    PubMed Central

    Muro, H.; Shirasawa, H.; Kosugi, I.; Nakamura, S.

    1993-01-01

    To analyze the pathological changes occurring in Fc receptors (FcRs) in sinusoidal endothelial cells (SECs) in chronic liver diseases, we first characterized immunohistochemically the SEC FcRs by using monoclonal antibodies (MAbs) to FcRs and then investigated the distribution of the SEC FcRs by using peroxidase-antiperoxidase IgG complexes as a ligand on frozen sections. MAb 2E1 to FcRII reacted with SECs in a similar manner to peroxidase-antiperoxidase IgG and blocked the peroxidase-antiperoxidase IgG binding to SECs, whereas MAbs 3G8 and Leu-11b to FcRIII did not. FcRs in normal liver were found along the sinusoidal walls, except for those in the outer periportal zones, but FcRs in chronic active hepatitis and cirrhosis were intermittently or focally absent. The lengths of the FcR-positive portion of sinusoids in unit areas were respectively about 54% and 76% of the normal values in active and inactive cirrhosis. Where FcRs were absent, the MAbs CD36, CD31, and EN4 revealed the presence of sinusoids and, in active cirrhosis, frequently the thickening of liver cell plates. The FcR-negative SECs in the outer periportal zones of normal livers were different from the SECs of other sites in the presence of PAL-E antigen and a rich amount of EN4 antigen, though these sinusoids possessed Kupffer cells and no perisinusoidal deposition of laminin. The FcR-negative SECs in liver diseases occasionally presented the character of ordinary blood vessels, viz., PAL-E antigen, CD34 antigen, and a deficiency of Kupffer cells, regardless of perisinusoidal laminin deposition. However, they preserved the character of normally FcR-possessing SECs, viz., CD36 antigen, and a small amount of EN4 and CD31 antigens. These findings indicate that the outer-periportal SECs in normal livers are phenotypically different from other SECs and that the SECs in diseased livers frequently undergo phenotypical changes, including loss of FcRs, regardless of perisinusoidal laminin deposition, i

  7. Gamma Knife

    MedlinePlus

    ... results are sent to the Gamma Knife®'s planning computer system. Together, physicians ( radiation oncologists and neurosurgeons) and medical physicists delineate targets and normal anatomical structures. They use a planning computer program to determine the exact spatial relationship between ...

  8. Gamma watermarking

    DOEpatents

    Ishikawa, Muriel Y.; Wood, Lowell L.; Lougheed, Ronald W.; Moody, Kenton J.; Wang, Tzu-Fang

    2004-05-25

    A covert, gamma-ray "signature" is used as a "watermark" for property identification. This new watermarking technology is based on a unique steganographic or "hidden writing" digital signature, implemented in tiny quantities of gamma-ray-emitting radioisotopic material combinations, generally covertly emplaced on or within an object. This digital signature may be readily recovered at distant future times, by placing a sensitive, high energy-resolution gamma-ray detecting instrument reasonably precisely over the location of the watermark, which location may be known only to the object's owner; however, the signature is concealed from all ordinary detection means because its exceedingly low level of activity is obscured by the natural radiation background (including the gamma radiation naturally emanating from the object itself, from cosmic radiation and material surroundings, from human bodies, etc.). The "watermark" is used in object-tagging for establishing object identity, history or ownership. It thus may serve as an aid to law enforcement officials in identifying stolen property and prosecuting theft thereof. Highly effective, potentially very low cost identification-on demand of items of most all types is thus made possible.

  9. Crossing the Vascular Wall: Common and Unique Mechanisms Exploited by Different Leukocyte Subsets during Extravasation.

    PubMed

    Schnoor, Michael; Alcaide, Pilar; Voisin, Mathieu-Benoit; van Buul, Jaap D

    2015-01-01

    Leukocyte extravasation is one of the essential and first steps during the initiation of inflammation. Therefore, a better understanding of the key molecules that regulate this process may help to develop novel therapeutics for treatment of inflammation-based diseases such as atherosclerosis or rheumatoid arthritis. The endothelial adhesion molecules ICAM-1 and VCAM-1 are known as the central mediators of leukocyte adhesion to and transmigration across the endothelium. Engagement of these molecules by their leukocyte integrin receptors initiates the activation of several signaling pathways within both leukocytes and endothelium. Several of such events have been described to occur during transendothelial migration of all leukocyte subsets, whereas other mechanisms are known only for a single leukocyte subset. Here, we summarize current knowledge on regulatory mechanisms of leukocyte extravasation from a leukocyte and endothelial point of view, respectively. Specifically, we will focus on highlighting common and unique mechanisms that specific leukocyte subsets exploit to succeed in crossing endothelial monolayers.

  10. Crossing the Vascular Wall: Common and Unique Mechanisms Exploited by Different Leukocyte Subsets during Extravasation

    PubMed Central

    Schnoor, Michael; Alcaide, Pilar; Voisin, Mathieu-Benoit; van Buul, Jaap D.

    2015-01-01

    Leukocyte extravasation is one of the essential and first steps during the initiation of inflammation. Therefore, a better understanding of the key molecules that regulate this process may help to develop novel therapeutics for treatment of inflammation-based diseases such as atherosclerosis or rheumatoid arthritis. The endothelial adhesion molecules ICAM-1 and VCAM-1 are known as the central mediators of leukocyte adhesion to and transmigration across the endothelium. Engagement of these molecules by their leukocyte integrin receptors initiates the activation of several signaling pathways within both leukocytes and endothelium. Several of such events have been described to occur during transendothelial migration of all leukocyte subsets, whereas other mechanisms are known only for a single leukocyte subset. Here, we summarize current knowledge on regulatory mechanisms of leukocyte extravasation from a leukocyte and endothelial point of view, respectively. Specifically, we will focus on highlighting common and unique mechanisms that specific leukocyte subsets exploit to succeed in crossing endothelial monolayers. PMID:26568666

  11. Recent insights into endothelial control of leukocyte extravasation.

    PubMed

    Hordijk, Peter L

    2016-04-01

    In the process of leukocyte migration from the circulation across the vascular wall, the crosstalk with endothelial cells that line the blood vessels is essential. It is now firmly established that in endothelial cells important signaling events are initiated upon leukocyte adhesion that impinge on the regulation of cell-cell contact and control the efficiency of transendothelial migration. In addition, several external factors such as shear force and vascular stiffness were recently identified as important regulators of endothelial signaling and, consequently, leukocyte transmigration. Here, I review recent insights into endothelial signaling events that are linked to leukocyte migration across the vessel wall. In this field, protein phosphorylation and Rho-mediated cytoskeletal dynamics are still widely studied using increasingly sophisticated mouse models. In addition, activation of tyrosine phosphatases, changes in endothelial cell stiffness as well as different vascular beds have all been established as important factors in endothelial signaling and leukocyte transmigration. Finally, I address less-well-studied but interesting components in the endothelium that also control transendothelial migration, such as the ephrins and their Eph receptors, that provide novel insights in the complexity associated with this process.

  12. Leukocyte transport by red blood cells in a microvessel

    NASA Astrophysics Data System (ADS)

    Freund, Jonathan

    2009-11-01

    A simulation model is used to study the transport of relatively large, spherical, and stiff white blood cells (leukocytes) by the relatively smaller and highly flexible red cell as they flow in the microcirculation. Their interaction dynamics are thought to be an important component of the inflammation response, in which leukocytes bind to the walls of blood vessels. The red cells are modeled in the simulations as highly deformable three-dimensional shells encasing a Newtonian fluid, and the viscous-flow equation is solved via a boundary integral formulation in which the cell shapes discretized by global spectral basis functions. For slow flow rates, it is found that the leukocyte is predominantly adjacent the vessel walls, whereas for faster flow rates this configuration appears to become unstable and the leukocyte traverses the whole vessel in a seemingly random fashion. For the straight round tubes simulated thus far, the stable leukocyte stand-off distance is always beyond the range of the binding molecules that capture it, which suggests that vessel inhomogeneities or interactions with other white cells are needed to create contact and thereby binding with the vessel walls.

  13. Preferential adhesion of leukocytes near bifurcations is endothelium independent.

    PubMed

    Tousi, Nazanin; Wang, Bin; Pant, Kapil; Kiani, Mohammad F; Prabhakarpandian, Balabhaskar

    2010-12-01

    Leukocyte-endothelial interactions play central roles in many pathological conditions. However, the in vivo mechanisms responsible for nonuniform spatial distribution of adhering leukocytes to endothelial cells in microvascular networks are not clear. We used a combination of in vitro and in vivo methodologies to explain of this complex phenomenon. A mouse cremaster muscle model was used to study the spatial distribution of leukocyte-endothelial cell interaction in vivo. A PDMS-based synthetic microvascular network (SMN) device was used to study interactions of functionalized microspheres using a receptor-ligand system in a (endothelial) cell-free environment for the in vitro studies. Our in vivo and in vitro findings indicate that both leukocytes in vivo and microspheres in vitro preferentially adhere near bifurcation (within 1-2 diameters from the bifurcation). This adhesion pattern was found to be independent of the diameter of the vessels. These findings support our hypothesis that the fluidic patterns near bifurcations/junctions, and not the presence or cellular aspects of the system (e.g. cell deformation, cell signaling, heterogeneous distribution of adhesion molecules), is the main controlling factor behind the preferential adhesion patterns of leukocytes near bifurcations. PMID:20624406

  14. Immunoglobulin Fc Heterodimer Platform Technology: From Design to Applications in Therapeutic Antibodies and Proteins

    PubMed Central

    Ha, Ji-Hee; Kim, Jung-Eun; Kim, Yong-Sung

    2016-01-01

    The monospecific and bivalent characteristics of naturally occurring immunoglobulin G (IgG) antibodies depend on homodimerization of the fragment crystallizable (Fc) regions of two identical heavy chains (HCs) and the subsequent assembly of two identical light chains (LCs) via disulfide linkages between each HC and LC. Immunoglobulin Fc heterodimers have been engineered through modifications to the CH3 domain interface, with different mutations on each domain such that the engineered Fc fragments, carrying the CH3 variant pair, preferentially form heterodimers rather than homodimers. Many research groups have adopted different strategies to generate Fc heterodimers, with the goal of high heterodimerization yield, while retaining biophysical and biological properties of the wild-type Fc. Based on their ability to enforce heterodimerization between the two different HCs, the established Fc heterodimers have been extensively exploited as a scaffold to generate bispecific antibodies (bsAbs) in full-length IgG and IgG-like formats. These have many of the favorable properties of natural IgG antibodies, such as high stability, long serum half-life, low immunogenicity, and immune effector functions. As of July 2016, more than seven heterodimeric Fc-based IgG-format bsAbs are being evaluated in clinical trials. In addition to bsAbs, heterodimeric Fc technology is very promising for the generation of Fc-fused proteins and peptides, as well as cytokines (immunocytokines), which can present the fusion partners in the natural monomeric or heterodimeric form rather than the artificial homodimeric form with wild-type Fc. Here, we present relevant concepts and strategies for the generation of heterodimeric Fc proteins, and their application in the development of bsAbs in diverse formats for optimal biological activity. In addition, we describe wild-type Fc-fused monomeric and heterodimeric proteins, along with the difficulties associated with their preparations, and discuss the

  15. Characterization and screening of IgG binding to the neonatal Fc receptor

    PubMed Central

    Neuber, Tobias; Frese, Katrin; Jaehrling, Jan; Jäger, Sebastian; Daubert, Daniela; Felderer, Karin; Linnemann, Mechthild; Höhne, Anne; Kaden, Stefan; Kölln, Johanna; Tiller, Thomas; Brocks, Bodo; Ostendorp, Ralf; Pabst, Stefan

    2014-01-01

    The neonatal Fc receptor (FcRn) protects immunoglobulin G (IgG) from degradation and increases the serum half-life of IgG, thereby contributing to a higher concentration of IgG in the serum. Because altered FcRn binding may result in a reduced or prolonged half-life of IgG molecules, it is advisable to characterize Fc receptor binding of therapeutic antibody lead candidates prior to the start of pre-clinical and clinical studies. In this study, we characterized the interactions between FcRn of different species (human, cynomolgus monkey, mouse and rat) and nine IgG molecules from different species and isotypes with common variable heavy (VH) and variable light chain (VL) domains. Binding was analyzed at acidic and neutral pH using surface plasmon resonance (SPR) and biolayer interferometry (BLI). Furthermore, we transferred the well-accepted, but low throughput SPR-based method for FcRn binding characterization to the BLI-based Octet platform to enable a higher sample throughput allowing the characterization of FcRn binding already during early drug discovery phase. We showed that the BLI-based approach is fit-for-purpose and capable of discriminating between IgG molecules with significant differences in FcRn binding affinities. Using this high-throughput approach we investigated FcRn binding of 36 IgG molecules that represented all VH/VL region combinations available in the fully human, recombinant antibody library Ylanthia®. Our results clearly showed normal FcRn binding profiles for all samples. Hence, the variations among the framework parts, complementarity-determining region (CDR) 1 and CDR2 of the fragment antigen binding (Fab) domain did not significantly change FcRn binding. PMID:24802048

  16. Multitasking by Exploitation of Intracellular Transport Functions: The Many Faces of FcRn

    PubMed Central

    Ward, E. Sally; Ober, Raimund J.

    2015-01-01

    The MHC Class I-related receptor, FcRn, transports antibodies of the immunoglobulin G (IgG) class within and across a diverse array of different cell types. Through this transport, FcRn serves multiple roles throughout adult life that extend well beyond its earlier defined function of transcytosing IgGs from mother to offspring. These roles include the maintenance of IgG levels and the delivery of antigen in the form of immune complexes to degradative compartments within cells. Recent studies have led to significant advances in knowledge of the intracellular trafficking of FcRn and (engineered) IgGs at both the molecular and cellular levels. The engineering of FcRn–IgG (or Fc) interactions to generate antibodies of increased longevity represents an area of active interest, particularly in the light of the expanding use of antibodies in therapy. The strict pH dependence of FcRn–IgG interactions, with binding at pH 6 that becomes essentially undetectable as near neutral pH is approached, is essential for efficient transport. The requirement for retention of low affinity at near neutral pH increases the complexity of engineering antibodies for increased half-life. Conversely, engineered IgGs that have gained significant binding for FcRn at this pH can be potent inhibitors of FcRn that lower endogenous IgG levels and have multiple potential uses as therapeutics. In addition, molecular studies of FcRn–IgG interactions indicate that mice have limitations as preclinical models for FcRn function, primarily due to cross-species differences in FcRn-binding specificity. PMID:19755184

  17. A prominent lack of IgG1-Fc fucosylation of platelet alloantibodies in pregnancy.

    PubMed

    Kapur, Rick; Kustiawan, Iwan; Vestrheim, Anne; Koeleman, Carolien A M; Visser, Remco; Einarsdottir, Helga K; Porcelijn, Leendert; Jackson, Dave; Kumpel, Belinda; Deelder, André M; Blank, Dennis; Skogen, Björn; Killie, Mette Kjaer; Michaelsen, Terje E; de Haas, Masja; Rispens, Theo; van der Schoot, C Ellen; Wuhrer, Manfred; Vidarsson, Gestur

    2014-01-23

    Immunoglobulin G (IgG) formed during pregnancy against human platelet antigens (HPAs) of the fetus mediates fetal or neonatal alloimmune thrombocytopenia (FNAIT). Because antibody titer or isotype does not strictly correlate with disease severity, we investigated by mass spectrometry variations in the glycosylation at Asn297 in the IgG Fc because the composition of this glycan can be highly variable, affecting binding to phagocyte IgG-Fc receptors (FcγR). We found markedly decreased levels of core fucosylation of anti-HPA-1a-specific IgG1 from FNAIT patients (n = 48), but not in total serum IgG1. Antibodies with a low amount of fucose displayed higher binding affinity to FcγRIIIa and FcγRIIIb, but not to FcγRIIa, compared with antibodies with a high amount of Fc fucose. Consequently, these antibodies with a low amount of Fc fucose showed enhanced phagocytosis of platelets using FcγRIIIb(+) polymorphonuclear cells or FcγRIIIa(+) monocytes as effector cells, but not with FcγRIIIa(-) monocytes. In addition, the degree of anti-HPA-1a fucosylation correlated positively with the neonatal platelet counts in FNAIT, and negatively to the clinical disease severity. In contrast to the FNAIT patients, no changes in core fucosylation were observed for anti-HLA antibodies in refractory thrombocytopenia (post platelet transfusion), indicating that the level of fucosylation may be antigen dependent and/or related to the immune milieu defined by pregnancy.

  18. A prominent lack of IgG1-Fc fucosylation of platelet alloantibodies in pregnancy

    PubMed Central

    Kapur, Rick; Kustiawan, Iwan; Vestrheim, Anne; Koeleman, Carolien A. M.; Visser, Remco; Einarsdottir, Helga K.; Porcelijn, Leendert; Jackson, Dave; Kumpel, Belinda; Deelder, André M.; Blank, Dennis; Skogen, Björn; Killie, Mette Kjaer; Michaelsen, Terje E.; de Haas, Masja; Rispens, Theo; van der Schoot, C. Ellen; Wuhrer, Manfred

    2014-01-01

    Immunoglobulin G (IgG) formed during pregnancy against human platelet antigens (HPAs) of the fetus mediates fetal or neonatal alloimmune thrombocytopenia (FNAIT). Because antibody titer or isotype does not strictly correlate with disease severity, we investigated by mass spectrometry variations in the glycosylation at Asn297 in the IgG Fc because the composition of this glycan can be highly variable, affecting binding to phagocyte IgG-Fc receptors (FcγR). We found markedly decreased levels of core fucosylation of anti-HPA-1a–specific IgG1 from FNAIT patients (n = 48), but not in total serum IgG1. Antibodies with a low amount of fucose displayed higher binding affinity to FcγRIIIa and FcγRIIIb, but not to FcγRIIa, compared with antibodies with a high amount of Fc fucose. Consequently, these antibodies with a low amount of Fc fucose showed enhanced phagocytosis of platelets using FcγRIIIb+ polymorphonuclear cells or FcγRIIIa+ monocytes as effector cells, but not with FcγRIIIa– monocytes. In addition, the degree of anti-HPA-1a fucosylation correlated positively with the neonatal platelet counts in FNAIT, and negatively to the clinical disease severity. In contrast to the FNAIT patients, no changes in core fucosylation were observed for anti-HLA antibodies in refractory thrombocytopenia (post platelet transfusion), indicating that the level of fucosylation may be antigen dependent and/or related to the immune milieu defined by pregnancy. PMID:24243971

  19. The localization of indium-111-leukocytes, gallium-67-polyclonal IgG and other radioactive agents in acute focal inflammatory lesions.

    PubMed

    McAfee, J G; Gagne, G; Subramanian, G; Schneider, R F

    1991-11-01

    A variety of radioactive agents, injected directly intravenously have demonstrated foci of inflammation by gamma camera imaging, avoiding the in vitro preparation of labeled leukocytes. This study sought to find out if any of these agents mimicked the biodistribution in abscesses and non-target organs of labeled mixed leukocyte suspensions. Eight different agents were compared with 111In-oxine labeled leukocytes in an acute soft tissue E. coli abscess and an acute arthritic lesion in 24 dogs one day after intravenous administration. These included 67Ga-citrate, human and canine polyclonal immunoglobulin (IgG), rabbit anti-dog polyclonal IgG, serum albumin, monoclonal antibody TNT-1 F(ab')2 against nuclear antigens, 57Co-porphyrin and serum albumin nanocolloid. None of these agents achieved abscess concentrations approaching those obtained with labeled leukocytes, and their abscess/blood and abscess/muscle concentration ratios were considerably lower. No statistically significant differences were found between the different radiolabeled proteins evaluated. The abscess concentration of 99mTc-nanocolloid was much lower than that of other agents, and the results with the oldest agent, 67Ga-citrate, were disappointing in these acute experiments. PMID:1941149

  20. Effects of cytokines and periodontopathic bacteria on the leukocyte function-associated antigen 1/intercellular adhesion molecule 1 pathway in gingival fibroblasts in adult periodontitis.

    PubMed Central

    Hayashi, J; Saito, I; Ishikawa, I; Miyasaka, N

    1994-01-01

    We investigated the effects of inflammatory cytokines and periodontopathic bacteria on expression of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1, and E-selectin (endothelial leukocyte adhesion molecule 1) in cultured human gingival fibroblasts (HGF). Cell surface ICAM-1 was upregulated on HGF under transcriptional control by exposure not only to interleukin-1 beta, tumor necrosis factor alpha, and gamma interferon but also to sonic extracts prepared from Porphyromonas gingivalis and Prevotella intermedia (nigrescens) and lipopolysaccharides from Escherichia coli. However, these stimuli induced only minimal expression of vascular cell adhesion molecule 1 and E-selectin on HGF. Binding assays using HGF and Molt 4, the human T-cell leukemia cell line, showed induced ICAM-1 to be functional, and the increased binding was blocked by a combination of monoclonal antibodies against ICAM-1 and leukocyte function-associated antigen 1. Furthermore, gingival tissues from adult periodontitis patients showed increased mRNA expression of ICAM-1 compared with that in tissues from normal healthy donors. In immunohistological analysis, we also observed in vivo that the expression of ICAM-1 on fibroblasts in adult periodontitis tissues was greater than that in normal gingiva. Thus, the overexpression of ICAM-1 on gingival fibroblasts induced by cytokines and periodontopathic bacteria is speculated to be deeply involved in the accumulation and retention of leukocyte function-associated antigen 1-bearing leukocytes in adult periodontitis lesions. Images PMID:7525481

  1. Effects of cytokines and periodontopathic bacteria on the leukocyte function-associated antigen 1/intercellular adhesion molecule 1 pathway in gingival fibroblasts in adult periodontitis.

    PubMed

    Hayashi, J; Saito, I; Ishikawa, I; Miyasaka, N

    1994-12-01

    We investigated the effects of inflammatory cytokines and periodontopathic bacteria on expression of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1, and E-selectin (endothelial leukocyte adhesion molecule 1) in cultured human gingival fibroblasts (HGF). Cell surface ICAM-1 was upregulated on HGF under transcriptional control by exposure not only to interleukin-1 beta, tumor necrosis factor alpha, and gamma interferon but also to sonic extracts prepared from Porphyromonas gingivalis and Prevotella intermedia (nigrescens) and lipopolysaccharides from Escherichia coli. However, these stimuli induced only minimal expression of vascular cell adhesion molecule 1 and E-selectin on HGF. Binding assays using HGF and Molt 4, the human T-cell leukemia cell line, showed induced ICAM-1 to be functional, and the increased binding was blocked by a combination of monoclonal antibodies against ICAM-1 and leukocyte function-associated antigen 1. Furthermore, gingival tissues from adult periodontitis patients showed increased mRNA expression of ICAM-1 compared with that in tissues from normal healthy donors. In immunohistological analysis, we also observed in vivo that the expression of ICAM-1 on fibroblasts in adult periodontitis tissues was greater than that in normal gingiva. Thus, the overexpression of ICAM-1 on gingival fibroblasts induced by cytokines and periodontopathic bacteria is speculated to be deeply involved in the accumulation and retention of leukocyte function-associated antigen 1-bearing leukocytes in adult periodontitis lesions. PMID:7525481

  2. Improving diagnosis of appendicitis. Early autologous leukocyte scanning.

    PubMed

    DeLaney, A R; Raviola, C A; Weber, P N; McDonald, P T; Navarro, D A; Jasko, I

    1989-10-01

    A prospective nonrandomized study investigating the accuracy and utility of autologous leukocyte scanning in the diagnosis of apendicitis was performed. One hundred patients in whom the clinical diagnosis of appendicitis was uncertain underwent indium 111 oxyquinoline labelling of autologous leukocytes and underwent scanning 2 hours following reinjection. Of 32 patients with proved appendicitis, three scans revealed normal results (false-negative rate, 0.09). Of 68 patients without appendicitis, three scans had positive results (false-positive rate, 0.03; sensitivity, 0.91; specificity, 0.97; predictive value of positive scan, 0.94; predictive value of negative scan, 0.96; and overall accuracy, 0.95). Scan results altered clinical decisions in 19 patients. In 13 cases, the scan produced images consistent with diagnoses other than appendicitis, expediting appropriate management. Early-imaging111 In oxyquinoline autologous leukocyte scanning is a practical and highly accurate adjunct for diagnosing appendicitis.

  3. Occult purulent pericarditis detected by indium-111 leukocyte imaging

    SciTech Connect

    Greenberg, M.L.; Niebulski, H.I.; Uretsky, B.F.; Salerni, R.; Klein, H.A.; Forstate, W.J.; Starzl, T.E.

    1984-05-01

    Leukocyte imaging with indium-111 is a relatively new technique which, to this point in time, has been discussed almost exclusively in the radiologic literature. Although this procedure has been used mainly to detect intra-abdominal infection, the thorax is routinely imaged along with the abdomen, and therefore detection of cardiac disease may be feasible. This case report is of a young woman after liver transplantation who developed occult purulent pericarditis initially detected by a leukocyte scan with indium-111. This case demonstrates that striking pericardial uptake on a whole-body indium-111 leukocyte scan can occur with purulent pericarditis, and it reemphasizes how insidiously purulent pericarditis may present in an immunosuppressed patient.

  4. [Case presentation: bovine leukocyte adhesion deficiency (BLAD) in Switzerland].

    PubMed

    Meylan, M; Abegg, R; Sager, H; Jungi, T W; Martig, J

    1997-01-01

    Bovine Leukocyte Adhesion Deficiency (BLAD) Syndrome is a lethal congenital immunodeficiency caused by the strong reduction in the expression of leukocyte integrins (beta 2 integrins) on the surface of leukocytes. Therefore, neutrophils from BLAD animals lack the capacity to adhere to the endothelium, a necessary step in their emigration into foci of infection. Due to the virtual absence of neutrophil-mediated host defense, animals suffer from recurrent infection of the respiratory and gastrointestinal tracts and finally succumb to infections. A 14 days old Holstein-Friesian calf showing omphalophlebitis and leukocytosis, was referred to our clinic. It was found to suffer from several febrile episodes of infection. The tentative diagnosis BLAD could be confirmed for the first time in Switzerland by flow cytometry, pedigree analysis and by restriction fragment length polymorphism. PMID:9411734

  5. Inhibition of human polymorphonuclear leukocyte chemotaxis by oxygenated sterol compounds

    SciTech Connect

    Gordon, L.I.; Bass, J.; Yachnin, S.

    1980-07-01

    When preincubated with certain oxygenated sterol compounds in lipoprotein-depleted serum (20% (vol/vol)), human polymorphonuclear leukocytes show inhibition of chemotaxis toward the synthetic dipeptide N-formylmethionylphenylalinine without alteration of random movement or loss of cell viability. These effects can occur at sterol concentrations as low as 6.25 ..mu..M and after as little as 5 min of preincubation, but they are increased at higher concentrations and longer preincubation times. The inhibition can be almost completely reversed by preincubation in lipoprotein-replete serum (human AB serum, 20% (vol/vol)) and may be partially corrected by addition of free cholesterol (0.125 mM) to the medium. These effects are unlikely to be due to inhibition of cellular sterol synthesis, competition for chemotaxin membrane binding sites, or deactivation of the leukocytes but they may be a consequence of insertion of the sterol molecule into the leukocyte plasma membranes.

  6. LACTOFERRIN, AN IRON-BINBING PROTEIN NI NEUTROPHILIC LEUKOCYTES

    PubMed Central

    Masson, P. L.; Heremans, J. F.; Schonne, E.

    1969-01-01

    Lactoferrin, an iron-binding protein previously shown to occur in many external secretions, is identified as one of the major proteins present in human and guinea pig neutrophilic polymorphonuclear leukocytes. The identification of this protein in leukocyte extracts was based upon a comparison of its electrophoretic, antigenic, and iron-combining properties with the corresponding properties of the same protein isolated from human and guinea pig milk. Immunochemical quantitations showed that lactoferrin occurs in human neutrophilic leukocytes at the concentration of 3 µg per 106 cells. Tissue cultures from guinea pig bone marrow and spleen actively synthesized the protein, as shown both by net production of lactoferrin and incorporation of labeled amino acids into the protein. Immunohistochemical data indicate that lactoferrin first appears in myeloid cells at the stage of the promyelocyte. PMID:4979954

  7. Prokaryotic peptides that block leukocyte adherence to selectins

    PubMed Central

    1993-01-01

    Pertussis toxin binds target cells through the carbohydrate recognition properties of two subunits, S2 and S3, which share amino acid sequence similarity with the lectin domains of the eukaryotic selectin family. Selectins appear on inflamed endothelial cells and promote rolling of leukocytes by reversibly binding carbohydrates. S2, S3, and synthetic peptides representing their carbohydrate recognition domains competitively inhibited adherence of neutrophils to selectin-coated surfaces and to endothelial cells in vitro. These proteins and peptides also rapidly upregulated the function of the leukocyte integrin CD11b/CD18. These findings implicate mimicry of eukaryotic selectins by prokaryotic adhesive ligands and link the mechanisms underlying leukocyte trafficking to microbial pathogenesis. PMID:7688793

  8. Improving diagnosis of appendicitis. Early autologous leukocyte scanning

    SciTech Connect

    DeLaney, A.R.; Raviola, C.A.; Weber, P.N.; McDonald, P.T.; Navarro, D.A.; Jasko, I. )

    1989-10-01

    A prospective nonrandomized study investigating the accuracy and utility of autologous leukocyte scanning in the diagnosis of appendicitis was performed. One hundred patients in whom the clinical diagnosis of appendicitis was uncertain underwent indium 111 oxyquinoline labelling of autologous leukocytes and underwent scanning 2 hours following reinjection. Of 32 patients with proved appendicitis, three scans revealed normal results (false-negative rate, 0.09). Of 68 patients without appendicitis, three scans had positive results (false-positive rate, 0.03; sensitivity, 0.91; specificity, 0.97; predictive value of positive scan, 0.94; predictive value of negative scan, 0.96; and overall accuracy, 0.95). Scan results altered clinical decisions in 19 patients. In 13 cases, the scan produced images consistent with diagnoses other than appendicitis, expediting appropriate management. Early-imaging In 111 oxyquinoline autologous leukocyte scanning is a practical and highly accurate adjunct for diagnosing appendicitis.

  9. Ethanol Inhibits High-Affinity Immunoglobulin E Receptor (FcεRI) Signaling in Mast Cells by Suppressing the Function of FcεRI-Cholesterol Signalosome.

    PubMed

    Draberova, Lubica; Paulenda, Tomas; Halova, Ivana; Potuckova, Lucie; Bugajev, Viktor; Bambouskova, Monika; Tumova, Magda; Draber, Petr

    2015-01-01

    Ethanol has multiple effects on biochemical events in a variety of cell types, including the high-affinity immunoglobulin E receptor (FcεRI) signaling in antigen-activated mast cells. However, the underlying molecular mechanism remains unknown. To get better understanding of the effect of ethanol on FcεRI-mediated signaling we examined the effect of short-term treatment with non-toxic concentrations of ethanol on FcεRI signaling events in mouse bone marrow-derived mast cells. We found that 15 min exposure to ethanol inhibited antigen-induced degranulation, calcium mobilization, expression of proinflammatory cytokine genes (tumor necrosis factor-α, interleukin-6, and interleukin-13), and formation of reactive oxygen species in a dose-dependent manner. Removal of cellular cholesterol with methyl-β-cyclodextrin had a similar effect and potentiated some of the inhibitory effects of ethanol. In contrast, exposure of the cells to cholesterol-saturated methyl-β-cyclodextrin abolished in part the inhibitory effect of ethanol on calcium response and production of reactive oxygen species, supporting lipid-centric theories of ethanol action on the earliest stages of mast cell signaling. Further studies showed that exposure to ethanol and/or removal of cholesterol inhibited early FcεRI activation events, including tyrosine phosphorylation of the FcεRI β and γ subunits, SYK kinases, LAT adaptor protein, phospholipase Cγ, STAT5, and AKT and internalization of aggregated FcεRI. Interestingly, ethanol alone, and particularly in combination with methyl-β-cyclodextrin, enhanced phosphorylation of negative regulatory tyrosine 507 of LYN kinase. Finally, we found that ethanol reduced passive cutaneous anaphylactic reaction in mice, suggesting that ethanol also inhibits FcεRI signaling under in vivo conditions. The combined data indicate that ethanol interferes with early antigen-induced signaling events in mast cells by suppressing the function of Fc

  10. Quantification of leukocyte migration: improvement of a method.

    PubMed

    Sunder-Plassmann, G; Hofbauer, R; Sengoelge, G; Hörl, W H

    1996-01-01

    Eighteen different permeable membrane supports with and without confluent endothelial cell monolayers were incubated with normal donor derived neutrophils in the upper chambers of a 24 multiwell double chamber system. In order to study transmembrane or transendothelial leukocyte migration leukocytes were stimulated by chemoattractants, or endothelial cells were activated by IL-1. After coincubation the membrane supports building the upper chambers were discarded. Using this technique, leukocytes that had migrated into the lower chamber were exposed to the fluorescent dye calcein AM without additional washing or transfer steps. Absolute cell counts were determined computer assisted using dilution series of calcein AM labeled leukocytes as standards. Serial dilutions of neutrophils exposed to calcein AM showed reproducible linear fluorescence intensity, and relative fluorescence intensity correlated significant with cell counts (r2 = 0.974, p < 0.0001). Out of 18 membrane supports only one was suitable for our assay set up. Best technical and optical performance was achieved with a membrane made of polyethylene terephtalate with a pore size of 3 mm at a pore density of 0.8 x 10(6)/cm2. Stimulation of leukocytes or endothelium by FMLP or IL-1 revealed an increase of transendothelial migration to 7.2 +/- 1.8 x 10(5) PMN and 5.1 +/- 0.7 x 10(5) PMN respectively if compared with medium (0.6 +/- 0.2 x 10(5) PMN). IL-1 induced migration of neutrophils was inhibited by anti IL-1 autoantibodies derived from chronic renal failure patients (IL-1: 100% of PMN migrated, anti IL-1 antibody: 39% of PMN migrated, control antibody: 84% of PMN migrated). In summary, a simple fluorimetric assay was established for the quantification of transmembrane and transendothelial leukocyte migration. PMID:8675234

  11. Upregulation of Leukocytic Syncytin-1 in Acute Myeloid Leukemia Patients

    PubMed Central

    Sun, Yi; Zhu, Hongyan; Song, Jianxin; Jiang, Yaxian; Ouyang, Hongmei; Huang, Rongzhong; Zhang, Guiqian; Fan, Xin; Tao, Rui; Jiang, Jie; Niu, Hua

    2016-01-01

    Background Syncytin-1, a cell membrane-localizing fusogen, is abnormally expressed in several cancers, including endometrial cancer, breast cancer, and leukemia. Although abnormal syncytin-1 expression has been detected in two-thirds of leukemia blood samples, its expression profile in acute leukemia patients has not yet been analyzed. Material/Methods Bone marrow samples from 50 acute myelogenous leukemia (AML) cases and 14 B-cell acute lymphocytic leukemia (B-cell ALL) patients were subjected to flow cytometry to assess leukocyte type distributions and leukocytic syncytin-1 surface expression. RT-PCR was applied to assess leukocytic syncytin-1 mRNA expression. Statistical analysis was applied to compare syncytin-1 expression between AML and B-cell ALL patients across blasts, granulocytes, lymphocytes, and monocytes as well as to determine clinical factors statistically associated with changes in syncytin-1 expression. Results The leukocyte type distributions of the AML and B-cell ALL cohorts highly overlapped, with an observable difference in blast distribution between the 2 cohorts. The AML cohort displayed significantly greater syncytin-1 surface and mRNA expression (p<0.05). Syncytin-1 surface and mRNA expression was significantly increased across all 4 leukocyte types (p<0.05). The percentage of syncytin-1-expressing blasts was significantly greater in AML patients (p<0.05), with blasts showing the largest fold-change in syncytin-1 expression (p<0.05). M5, M5a, and M5b AML patients displayed significantly higher syncytin-1 surface expression relative to all other AML French-American-British (FAB) classifications (p<0.05). Conclusions These findings suggest leukocytic syncytin-1 expression may play a role in the development and/or maintenance of the AML phenotype and the acute monocytic leukemia phenotype in particular. PMID:27393911

  12. Sources of interferon-gamma (IFN-gamma) in early immune response to Listeria monocytogenes.

    PubMed

    Thäle, Carsten; Kiderlen, Albrecht F

    2005-01-01

    Early, innate production of interferon-gamma (IFN-gamma) is a critical step in immunological defense against certain pathogens such as intracellular bacteria (e.g. Listeria monocytogenes), viruses and fungi. While activated T cells and activated natural killer (NK) cells were initially thought to be the only relevant source of IFN-gamma, macrophages (Mphi) and dendritic cells can also be stimulated to produce IFN-gamma in vitro under certain conditions. However, a convincing analysis at single cell level of the source(s) of IFN-gamma in the early immune response to an acute bacterial infection is still missing. In the light of controversial literature, the work presented here aimed to clarify the role of NK cells and other components of the innate cellular immune system in the early IFN-gamma production, thereby avoiding in vitro artifacts whenever possible. Immunocompetent C57BL/6 (wild type (WT)) and T and B cell-deficient C57BL/6 rag-1(-/-) (RAG) mice were infected intravenously with a pathogenic strain of L. monocytogenes. Leukocyte populations of spleen and liver were discriminated by characteristic surface markers and analyzed for intracellular interleukin (IL)-12 and IFN-gamma using flow cytometry. These cells have not been restimulated in vitro nor sorted before analysis. In RAG mice, at least, a large NK1.1+ cell population produced IFN-gamma 19 h p.i. No MHC class II+ population co-expressed intracellular IFN-gamma at this time point. For comparison with the immunocompetent situation, syngeneic WT mice were also infected and sacrificed 9, 19, and 29 h later. At 9 h p.i., the situation resembled that of uninfected mice. At 19 and 29 h p.i. it was again the NK1.1+ population that contained most of the IFN-gamma-positive events. MHC II + CD 19- Mphi/dendritic cells and MHC II+ CD19+ B cells did not co-express intracellular IFN-gamma at these time points. CD3+ T cells were also found to contain intracellular IFN-gamma; most were also CD8+ and some CD4+. These

  13. Single-chain Variable Fragment Albumin Fusions Bind the Neonatal Fc Receptor (FcRn) in a Species-dependent Manner

    PubMed Central

    Andersen, Jan Terje; Cameron, Jason; Plumridge, Andrew; Evans, Leslie; Sleep, Darrell; Sandlie, Inger

    2013-01-01

    Albumin has a serum half-life of 3 weeks in humans. This has been utilized to extend the serum persistence of biopharmaceuticals that are fused to albumin. In light of the fact that the neonatal Fc receptor (FcRn) is a key regulator of albumin homeostasis, it is crucial to address how fusion of therapeutics to albumin impacts binding to FcRn. Here, we report on a detailed molecular investigation on how genetic fusion of a short peptide or an single-chain variable fragment (scFv) fragment to human serum albumin (HSA) influences pH-dependent binding to FcRn from mouse, rat, monkey, and human. We have found that fusion to the N- or C-terminal end of HSA only slightly reduces receptor binding, where the most noticeable effect is seen after fusion to the C-terminal end. Furthermore, in contrast to the observed strong binding to human and monkey FcRn, HSA and all HSA fusions bound very poorly to mouse and rat versions of the receptor. Thus, we demonstrate that conventional rodents are limited as preclinical models for analysis of serum half-life of HSA-based biopharmaceuticals. This finding is explained by cross-species differences mainly found within domain III (DIII) of albumin. Our data demonstrate that although fusion, particularly to the C-terminal end, may slightly reduce the affinity for FcRn, HSA is versatile as a carrier of biopharmaceuticals. PMID:23818524

  14. Generation and Characterization of an IgG4 Monomeric Fc Platform

    PubMed Central

    Shan, Lu; Colazet, Magali; Rosenthal, Kim L.; Yu, Xiang-Qing; Bee, Jared S.; Ferguson, Andrew; Damschroder, Melissa M.; Wu, Herren; Dall’Acqua, William F.; Tsui, Ping

    2016-01-01

    The immunoglobulin Fc region is a homodimer consisted of two sets of CH2 and CH3 domains and has been exploited to generate two-arm protein fusions with high expression yields, simplified purification processes and extended serum half-life. However, attempts to generate one-arm fusion proteins with monomeric Fc, with one set of CH2 and CH3 domains, are often plagued with challenges such as weakened binding to FcRn or partial monomer formation. Here, we demonstrate the generation of a stable IgG4 Fc monomer with a unique combination of mutations at the CH3-CH3 interface using rational design combined with in vitro evolution methodologies. In addition to size-exclusion chromatography and analytical ultracentrifugation, we used multi-angle light scattering (MALS) to show that the engineered Fc monomer exhibits excellent monodispersity. Furthermore, crystal structure analysis (PDB ID: 5HVW) reveals monomeric properties supported by disrupted interactions at the CH3-CH3 interface. Monomeric Fc fusions with Fab or scFv achieved FcRn binding and serum half-life comparable to wildtype IgG. These results demonstrate that this monomeric IgG4 Fc is a promising therapeutic platform to extend the serum half-life of proteins in a monovalent format. PMID:27479095

  15. Materno-Fetal Transfer of Preproinsulin Through the Neonatal Fc Receptor Prevents Autoimmune Diabetes.

    PubMed

    Culina, Slobodan; Gupta, Nimesh; Boisgard, Raphael; Afonso, Georgia; Gagnerault, Marie-Claude; Dimitrov, Jordan; Østerbye, Thomas; Justesen, Sune; Luce, Sandrine; Attias, Mikhaël; Kyewski, Bruno; Buus, Søren; Wong, F Susan; Lacroix-Desmazes, Sebastien; Mallone, Roberto

    2015-10-01

    The first signs of autoimmune activation leading to β-cell destruction in type 1 diabetes (T1D) appear during the first months of life. Thus, the perinatal period offers a suitable time window for disease prevention. Moreover, thymic selection of autoreactive T cells is most active during this period, providing a therapeutic opportunity not exploited to date. We therefore devised a strategy by which the T1D-triggering antigen preproinsulin fused with the immunoglobulin (Ig)G Fc fragment (PPI-Fc) is delivered to fetuses through the neonatal Fc receptor (FcRn) pathway, which physiologically transfers maternal IgGs through the placenta. PPI-Fc administered to pregnant PPIB15-23 T-cell receptor-transgenic mice efficiently accumulated in fetuses through the placental FcRn and protected them from subsequent diabetes development. Protection relied on ferrying of PPI-Fc to the thymus by migratory dendritic cells and resulted in a rise in thymic-derived CD4(+) regulatory T cells expressing transforming growth factor-β and in increased effector CD8(+) T cells displaying impaired cytotoxicity. Moreover, polyclonal splenocytes from nonobese diabetic (NOD) mice transplacentally treated with PPI-Fc were less diabetogenic upon transfer into NOD.scid recipients. Transplacental antigen vaccination provides a novel strategy for early T1D prevention and, further, is applicable to other immune-mediated conditions.

  16. Chlorotoxin-Fc fusion inhibits release of MMP-2 from pancreatic cancer cells.

    PubMed

    El-Ghlban, Samah; Kasai, Tomonari; Shigehiro, Tsukasa; Yin, Hong Xia; Sekhar, Sreeja; Ida, Mikiko; Sanchez, Anna; Mizutani, Akifumi; Kudoh, Takayuki; Murakami, Hiroshi; Seno, Masaharu

    2014-01-01

    Chlorotoxin (CTX) is a 36-amino acid peptide derived from Leiurus quinquestriatus (scorpion) venom, which inhibits low-conductance chloride channels in colonic epithelial cells. It has been reported that CTX also binds to matrix metalloproteinase-2 (MMP-2), membrane type-1 MMP, and tissue inhibitor of metalloproteinase-2, as well as CLC-3 chloride ion channels and other proteins. Pancreatic cancer cells require the activation of MMP-2 during invasion and migration. In this study, the fusion protein was generated by joining the CTX peptide to the amino terminus of the human IgG-Fc domain without a hinge domain, the monomeric form of chlorotoxin (M-CTX-Fc). The resulting fusion protein was then used to target pancreatic cancer cells (PANC-1) in vitro. M-CTX-Fc decreased MMP-2 release into the media of PANC-1 cells in a dose-dependent manner. M-CTX-Fc internalization into PANC-1 cells was observed. When the cells were treated with chlorpromazine (CPZ), the internalization of the fusion protein was reduced, implicating a clathrin-dependent internalization mechanism of M-CTX-Fc in PANC-1 cells. Furthermore, M-CTX-Fc clearly exhibited the inhibition of the migration depending on the concentration, but human IgG, as negative control of Fc, was not affected. The M-CTX-Fc may be an effective instrument for targeting pancreatic cancer.

  17. Demonstration of human immunoglobulin G Fc-binding activity in oral bacteria.

    PubMed Central

    Grenier, D; Michaud, J

    1994-01-01

    Nonimmune binding of immunoglobulins via the Fc fragment may reduce opsonization and phagocytosis of bacteria and is thus considered a virulence factor. The aim of this study was to investigate a wide range of oral bacterial strains for the presence of human immunoglobulin G (IgG) Fc-binding activity. A total of 132 strains representing 40 different gram-positive and gram negative bacterial species were tested for IgG Fc-binding activity by using a fast and simple dot blot procedure with horseradish peroxidase-conjugated Fc fragments from human IgG. Neither the human nor animal biotype of Porphyromonas gingivalis possessed IgG Fc-binding activity. The strongest positive reaction of gram-negative species with the IgG Fc fragments were obtained with strains of Prevotella intermedia and Fusobacterium nucleatum. Among the gram-positive bacteria tested, Peptostreptococcus micros, Lactobacillus spp., and several species of streptococci possessed IgG Fc-binding activity. In the present investigation, the ability of several oral bacterial species to bind IgG Fc fragments was demonstrated. This factor represents a potential virulence determinant as it may help pathogenic oral bacteria escape host defense mechanisms. PMID:7496956

  18. High Fc Density Particles Result in Binary Complement Activation but Tunable Macrophage Phagocytosis

    NASA Astrophysics Data System (ADS)

    Sulchek, Todd; Pacheco, Patricia; White, David

    2014-03-01

    Macrophage phagocytosis and complement system activation represent two key components of the immune system and both can be activated through the presentation of multiple Fc domains of IgG antibodies. We have created functionalized micro- and nanoparticles with various densities of Fc domains to understand the modulation of the immune system for eventual use as a novel immunomodulation platform. Phagocytosis assays were carried out by adding functionalized particles to macrophage cells and quantitatively determined using fluorescent microscopy and flow cytometry. Complement system activation by the functionalized particles in human serum was quantified with an enzyme immunoassay. Our phagocytosis assay revealed a strong dependence on particle size and Fc density. For small particles, as the Fc density increased, the number of particles phagocytosed also increased. Large particles were phagocytosed at significantly lower levels and showed no dependency on Fc density. Complement was successfully activated at levels comparable to positive controls for small particles at high Fc densities. However at low Fc densities, there is a significant decrease in complement activation. This result suggests a binary response for complement system activation with a threshold density for successful activation. Therefore, varying the Fc density on micro/nanoparticles resulted in a tunable response in macrophage phagocytosis while a more binary response for complement activation.

  19. Chlorotoxin-Fc fusion inhibits release of MMP-2 from pancreatic cancer cells.

    PubMed

    El-Ghlban, Samah; Kasai, Tomonari; Shigehiro, Tsukasa; Yin, Hong Xia; Sekhar, Sreeja; Ida, Mikiko; Sanchez, Anna; Mizutani, Akifumi; Kudoh, Takayuki; Murakami, Hiroshi; Seno, Masaharu

    2014-01-01

    Chlorotoxin (CTX) is a 36-amino acid peptide derived from Leiurus quinquestriatus (scorpion) venom, which inhibits low-conductance chloride channels in colonic epithelial cells. It has been reported that CTX also binds to matrix metalloproteinase-2 (MMP-2), membrane type-1 MMP, and tissue inhibitor of metalloproteinase-2, as well as CLC-3 chloride ion channels and other proteins. Pancreatic cancer cells require the activation of MMP-2 during invasion and migration. In this study, the fusion protein was generated by joining the CTX peptide to the amino terminus of the human IgG-Fc domain without a hinge domain, the monomeric form of chlorotoxin (M-CTX-Fc). The resulting fusion protein was then used to target pancreatic cancer cells (PANC-1) in vitro. M-CTX-Fc decreased MMP-2 release into the media of PANC-1 cells in a dose-dependent manner. M-CTX-Fc internalization into PANC-1 cells was observed. When the cells were treated with chlorpromazine (CPZ), the internalization of the fusion protein was reduced, implicating a clathrin-dependent internalization mechanism of M-CTX-Fc in PANC-1 cells. Furthermore, M-CTX-Fc clearly exhibited the inhibition of the migration depending on the concentration, but human IgG, as negative control of Fc, was not affected. The M-CTX-Fc may be an effective instrument for targeting pancreatic cancer. PMID:24511528

  20. Detection of deep venous thrombosis by indium-111 leukocyte scintigraphy

    SciTech Connect

    D'Alonzo, W.A. Jr.; Alavi, A.

    1986-05-01

    Indium-111-labeled leukocyte ((/sup 111/In)WBC) scintigraphy has been used successfully for detection of inflammation. Occasionally, noninflammatory collections of white blood cells such as hematomas or hemorrhage have been localized. We report a case in which unsuspected femoral deep venous thrombosis was diagnosed on an (/sup 111/In)WBC leukocyte scan performed for detection of osteomyelitis. Readers are advised to avoid interpreting all vascular (/sup 111/In)WBC localization as necessarily infectious. This may be of particular significance in patients with vascular grafts.

  1. Diversity of teleost leukocyte molecules: role of alternative splicing.

    PubMed

    Maisey, Kevin; Imarai, Mónica

    2011-11-01

    Alternative splicing is an important mechanism of gene expression control that also produces a large proteome from a limited number of genes. In the immune system of mammals, numerous relevant genes have been found to undergo alternative splicing that contributes to the complexity of immune response. An increasing number of reports have recently indicated that alternative splicing also occurs in other vertebrates, such as fish. In this review we summarize the general features of such molecular events in cytokines and leukocyte co-receptors and their contribution to diversity and regulation of fish leukocytes. PMID:20723604

  2. Therapeutic hypothermia impacts leukocyte kinetics after cardiac arrest

    PubMed Central

    Dufner, Matthias C.; Andre, Florian; Stiepak, Jan; Zelniker, Thomas; Chorianopoulos, Emmanuel; Preusch, Michael; Katus, Hugo A.

    2016-01-01

    Background Patients admitted to the hospital after primarily successful cardiopulmonary resuscitation (CPR) are at a very high risk for neurologic deficits and death. Targeted temperature management (TTM) for mild therapeutic hypothermia has been shown to improve survival compared to standard treatment. Acute cardiovascular events, such as myocardial infarction (MI), are a major cause for cardiac arrest (CA) in patients who undergo CPR. Recent findings have demonstrated the importance and impact of the leukocyte response following acute MI. Methods In this retrospective, single center study we enrolled 169 patients with CA due to non-traumatic causes and primarily successful CPR. A total of 111 subjects (66%) underwent TTM aiming for a target temperature of 32–34 °C. Results Analysis of 30 day follow up showed a significantly improved survival of all patients who received TTM compared to patients without hypothermia (P=0.0001). Furthermore TTM was an independent variable of good neurological outcome after 6 months (P=0.0030). Therapeutic hypothermia was found to be beneficial independent of differences in age and sex between both groups. While a higher rate of pneumonia was observed with TTM, this diagnosis had no additional impact on survival or neurological outcome. The beneficial effect on mortality remained significant in patients with the diagnosis of an acute cardiac event (P=0.0145). Next, we evaluated the kinetics of leukocytes in this group over the course of 7 days after CA. At presentation, patients showed a mean level of 16.5±6.7 of leukocytes per microliter. While this level stayed stable in the group of patients without hypothermia, patients who received TTM showed a significant decline of leukocyte levels resulting in significantly lower numbers of leukocytes on days 3 and 5 after CPR. Interestingly, these differences in leukocyte counts remained beyond the time period of TTM while C-reactive protein (CRP) levels were suppressed only during

  3. Investigating the Interaction between the Neonatal Fc Receptor and Monoclonal Antibody Variants by Hydrogen/Deuterium Exchange Mass Spectrometry*

    PubMed Central

    Jensen, Pernille Foged; Larraillet, Vincent; Schlothauer, Tilman; Kettenberger, Hubert; Hilger, Maximiliane; Rand, Kasper D.

    2015-01-01

    The recycling of immunoglobulins by the neonatal Fc receptor (FcRn) is of crucial importance in the maintenance of antibody levels in plasma and is responsible for the long half-lives of endogenous and recombinant monoclonal antibodies. From a therapeutic point of view there is great interest in understanding and modulating the IgG–FcRn interaction to optimize antibody pharmacokinetics and ultimately improve efficacy and safety. Here we studied the interaction between a full-length human IgG1 and human FcRn via hydrogen/deuterium exchange mass spectrometry and targeted electron transfer dissociation to map sites perturbed by binding on both partners of the IgG–FcRn complex. Several regions in the antibody Fc region and the FcRn were protected from exchange upon complex formation, in good agreement with previous crystallographic studies of FcRn in complex with the Fc fragment. Interestingly, we found that several regions in the IgG Fab region also showed reduced deuterium uptake. Our findings indicate the presence of hitherto unknown FcRn interaction sites in the Fab region or a possible conformational link between the IgG Fc and Fab regions upon FcRn binding. Further, we investigated the role of IgG glycosylation in the conformational response of the IgG–FcRn interaction. Removal of antibody glycans increased the flexibility of the FcRn binding site in the Fc region. Consequently, FcRn binding did not induce a similar conformational stabilization of deglycosylated IgG as observed for the wild-type glycosylated IgG. Our results provide new molecular insight into the IgG–FcRn interaction and illustrate the capability of hydrogen/deuterium exchange mass spectrometry to advance structural proteomics by providing detailed information on the conformation and dynamics of large protein complexes in solution. PMID:25378534

  4. beta. -Endorphin and related peptides suppress phorbol myristate acetate-induced respiratory burst in human polymorphonuclear leukocytes

    SciTech Connect

    Diamant, M.; Henricks, P.A.J.; Nijkamp, F.P.; de Wied, D. )

    1989-01-01

    In the present study, the immunomodulatory effect of {beta}-endorphin ({beta}-E) and shorter pro-opiomelancortin (POMC) fragments was evaluated by assessing their influence on respiratory burst in human polymorphonuclear leukocytes (PMN). The effect of the peptides on phorbol myristate acetate (PMA)-stimulated production of reactive oxygen metabolites was measured in a lucigenin-enhanced chemiluminescence (CL) assay. Both POMC peptides with opiate-like activity and their non-opioid derivatives were tested. With the exception of {alpha}-E, PMA-stimulated respiratory burst was suppressed by all POMC fragments tested. A U-shaped dose-response relation was observed. Doses lower than 10{sup {minus}17}M and higher than 10{sup {minus}8}M were without effect. {beta}-E and dT{beta}E both suppressed PMA-induced oxidative burst in human PMN at physiological concentrations. {gamma}-E and dT{gamma}E proved to be less potent inhibitors, reaching maximal effect at higher concentrations. DE{gamma}E exerted an even less pronounced but still significant suppressive effect at the concentration of 10{sup {minus}10}M. None of the endorphins tested was shown to affect resting oxidative metabolism in the PMN. The modulatory effects of the opioid peptides could not be blocked by the opioid antagonist naloxone.

  5. Expression of SOCS genes in normal and leukemic human leukocytes stimulated by prolactin, growth hormone and cytokines.

    PubMed

    Dogusan, Z; Hooghe-Peters, E L; Berus, D; Velkeniers, B; Hooghe, R

    2000-09-01

    To evaluate the possible role of the recently described family of suppressors of cytokine signaling (SOCS) factors in the human lympho-hemopoietic system, we have monitored SOCS factor expression, both constitutive and induced by either cytokines, prolactin (PRL) or growth hormone (GH), using polymerase chain reaction in normal and leukemic cells. CIS (cytokine-inducible SH2-containing protein), SOCS-2 and SOCS-3 were constitutively expressed in peripheral blood mononuclear leukocytes. SOCS-3 expression was enhanced by PRL or by IFN-gamma. In bone marrow cells and granulocytes, CIS expression was induced and SOCS-2 enhanced by IFN-gamma and by PRL. In tonsillar cells, CIS expression was increased and SOCS-2 was induced by IL-1beta, IL-6, PRL and GH. SOCS-3 expression was enhanced by IL-1beta. The expression of SOCS-7 was increased by IL-6, PRL and GH. In Raji B-lymphoma cells, the expression of SOCS-2 and SOCS-7 was enhanced by IL-1beta. In THP-1 myeloid leukemia cells pretreated with TPA (to induce receptors for IFN-gamma), IFN-gamma induced SOCS-2. Jurkat cells expressed more SOCS-2 when exposed to PRL. Original observations in this work include the first report on SOCS-7 induction by cytokines. Also our data shed new light on the possible involvement of PRL and GH in the cytokine network. These hormones could modulate the transduction of signals originating from receptors for various cytokines.

  6. The Effect of Hemiscorpius lepturus (Scorpionida: Hemiscorpiidae) Venom on Leukocytes and the Leukocyte Subgroups in Peripheral Blood of Rat

    PubMed Central

    Ghafourian, Mehri; Ganjalikhanhakemi, Neda; Hemmati, Ali Asghar; Dehghani, Rouhullah; Kooti, Wesam

    2016-01-01

    Background: The aim of this study was to investigate the effect of Hemiscorpius lepturus venom on leukocytes and the leukocyte subgroups in peripheral blood of rat. Methods: In this experimental study, sixty N-Mari rats were divided into three groups of 20 rats. Then the rats in each group were divided into four subgroups based on the blood sampling time that was 2, 6, 24 and 48 hours after the venom injection, respectively. The control group did not receive anything, however, the first and the second experimental groups received 0.1 and 0.01mg/kg of venom, subcutaneously. In accordance with a designated four sampling times, the blood sampling was carried out in three groups. After RBC lysis, the leukocytes and leukocyte sub-populations were determined and counted using appropriate hematological standard methods. Results: The leukocyte and the neutrophil count at two (P<0.05), six (P<0.01) and 24 (P<0.05) hours after the venom injection showed a significant decline compared with the control group, this decrease was significant at the dose of 0.1 mg/kg until 48 hours after the venom injection (P<0.05). The lymphocyte count showed a significant decline throughout the all hours of the experiment, compared with the control group (P<0.05). Conclusion: Leukocytes are probably affected by the cytotoxicity effect of the H. lepturus venom in a dose-dependent manner. This could be a wakeup call for the medical staff to perform quick and accurate treatment in the least time possible. PMID:27308274

  7. A PKC-SHP1 signaling axis desensitizes Fcγ receptor signaling by reducing the tyrosine phosphorylation of CBL and regulates FcγR mediated phagocytosis

    PubMed Central

    2014-01-01

    Background Fcγ receptors mediate important biological signals in myeloid cells including the ingestion of microorganisms through a process of phagocytosis. It is well-known that Fcγ receptor (FcγR) crosslinking induces the tyrosine phosphorylation of CBL which is associated with FcγR mediated phagocytosis, however how signaling molecules coordinate to desensitize these receptors is unclear. An investigation of the mechanisms involved in receptor desensitization will provide new insight into potential mechanisms by which signaling molecules may downregulate tyrosine phosphorylation dependent signaling events to terminate important signaling processes. Results Using the U937IF cell line, we observed that FcγR1 crosslinking induces the tyrosine phosphorylation of CBL, which is maximal at 5 min. followed by a kinetic pattern of dephosphorylation. An investigation of the mechanisms involved in receptor desensitization revealed that pretreatment of U937IF or J774 cells with PMA followed by Fcγ receptor crosslinking results in the reduced tyrosine phosphorylation of CBL and the abrogation of downstream signals, such as CBL-CRKL binding, Rac-GTP activation and the phagocytic response. Pretreatment of J774 cells with GF109203X, a PKC inhibitor was observed to block dephosphorylation of CBL and rescued the phagocytic response. We demonstrate that the PKC induced desensitization of FcγR/ phagocytosis is associated with the inactivation of Rac-GTP, which is deactivated in a hematopoietic specific phosphatase SHP1 dependent manner following ITAM stimulation. The effect of PKC on FcγR signaling is augmented by the transfection of catalytically active SHP1 and not by the transfection of catalytic dead SHP1 (C124S). Conclusions Our results suggest a functional model by which PKC interacts with SHP1 to affect the phosphorylation state of CBL, the activation state of Rac and the negative regulation of ITAM signaling i.e. Fcγ receptor mediated phagocytosis. These findings

  8. 21 CFR 864.7675 - Leukocyte peroxidase test.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Leukocyte peroxidase test. 864.7675 Section 864.7675 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7675...

  9. 21 CFR 864.7675 - Leukocyte peroxidase test.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Leukocyte peroxidase test. 864.7675 Section 864.7675 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7675...

  10. 21 CFR 864.7675 - Leukocyte peroxidase test.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Leukocyte peroxidase test. 864.7675 Section 864.7675 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7675...

  11. 21 CFR 864.7675 - Leukocyte peroxidase test.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Leukocyte peroxidase test. 864.7675 Section 864.7675 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7675...

  12. 21 CFR 864.7675 - Leukocyte peroxidase test.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Leukocyte peroxidase test. 864.7675 Section 864.7675 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7675...

  13. Uptake of /sup 111/In-labeled leukocytes by tumor

    SciTech Connect

    Fortner, A.; Datz, F.L.; Taylor, A. Jr.; Alazraki, N.

    1986-03-01

    The 111In-labeled leukocyte scan is a sensitive and specific technique for the detection and localization of abscesses. However, in reviewing an unselected series of 249 scans, six (2.3%) were false-positive cases in which leukocyte uptake by tumor mimicked an abscess. This represented 12% (6/51) with known tumor at the time of imaging. Five of the cases were primary or metastatic tumors to the soft tissues; the sixth was a skeletal metastasis. The intensity of tumor activity has been characterized as mild in the few cases of leukocyte uptake reported in the literature, suggesting that the degree of uptake is helpful in distinguishing tumor from abscess. In this study, however, variable degrees of tumor-associated activity were seen ranging from mild to very intense. These findings indicate that tumor accumulates labeled leukocytes more frequently than has been previously appreciated, that primary and metastatic neoplasms involving both the soft tissues and skeleton are involved, and that the intensity of uptake is not a reliable criterion to distinguish tumor from abscess.

  14. Leukocyte driven-decidual angiogenesis in early pregnancy

    PubMed Central

    Lima, Patricia DA; Zhang, Jianhong; Dunk, Caroline; Lye, Stephen J; Anne Croy, B

    2014-01-01

    Successful pregnancy and long-term, post-natal maternal and offspring cardiac, vascular and metabolic health require key maternal cardiovascular adaptations over gestation. Within the pregnant decidualizing uterus, coordinated vascular, immunological and stromal cell changes occur. Considerable attention has been given to the roles of uterine natural killer (uNK) cells in initiating decidual spiral arterial remodeling, a process normally completed by mid-gestation in mice and in humans. However, leukocyte roles in much earlier, region specific, decidual vascular remodeling are now being defined. Interest in immune cell-promoted vascular remodeling is driven by vascular aberrations that are reported in human gestational complications such as infertility, recurrent spontaneous abortion, preeclampsia (PE) and fetal growth restriction. Appropriate maternal cardiovascular responses during pregnancy protect mothers and their children from later cardiovascular disease risk elevation. One of the earliest uterine responses to pregnancy in species with hemochorial placentation is stromal cell decidualization, which creates unique niches for angiogenesis and leukocyte recruitment. In early decidua basalis, the aspect of the implantation site that will cradle the developing placenta and provide the major blood vessels to support mature placental functions, leukocytes are greatly enriched and display specialized properties. UNK cells, the most abundant leukocyte subset in early decidua basalis, have angiogenic abilities and are essential for normal early decidual angiogenesis. The regulation of uNK cells and their roles in determining maternal and progeny cardiovascular health over pregnancy and postpartum are discussed. PMID:25066422

  15. Recent advances in microscopic techniques for visualizing leukocytes in vivo

    PubMed Central

    Jain, Rohit; Tikoo, Shweta; Weninger, Wolfgang

    2016-01-01

    Leukocytes are inherently motile and interactive cells. Recent advances in intravital microscopy approaches have enabled a new vista of their behavior within intact tissues in real time. This brief review summarizes the developments enabling the tracking of immune responses in vivo. PMID:27239292

  16. Multiparticle adhesive dynamics: Hydrodynamic recruitment of rolling leukocytes

    PubMed Central

    King, Michael R.; Hammer, Daniel A.

    2001-01-01

    The slow rolling motion of leukocytes along the walls of blood vessels mediated by specific receptor-ligand adhesion is important in inflammation and occurs in postcapillary venules over a wide range of wall shear stresses and vessel diameters. The ability of hydrodynamic collisions between cells to induce capture of free-stream leukocytes to a selectin-bearing surface under shear flow was studied experimentally by using a cell-free assay. It was found that carbohydrate-coated spherical beads, representing model leukocytes, tend to attach to the adhesive wall 4–5 cell diameters up- or downstream of a slowly rolling or stationary adhesive bead. A key feature of such “hydrodynamic recruitment” is that only glancing, indirect collisions occurring close to the plane will result in downstream attachment. A direct numerical simulation of cell capture and rolling that includes multiparticle hydrodynamic interactions is shown to reproduce the observed behavior accurately. The theory predicts that hydrodynamic recruitment will occur in the absence of buoyancy effects and over a range of shear rates, suggesting that the mechanism may be important in vivo. This theory is supported by measurements of leukocyte capture in vivo using the hamster cheek pouch model. PMID:11752440

  17. Medical Applications of Leukocyte Surface Molecules—the CD molecules

    PubMed Central

    Zola, Heddy

    2006-01-01

    Leukocytes are the cells of the immune system and are centrally involved in defense against infection, in autoimmune disease, allergy, inflammation, and in organ graft rejection. Lymphomas and leukemias are malignancies of leukocytes, and the immune system is almost certainly involved in most other cancers. Each leukocyte expresses a selection of cell surface glycoproteins and glycolipids which mediate its interaction with antigen, with other components of the immune system, and with other tissues. It is therefore not surprising that the leukocyte surface molecules (CD molecules) have provided targets for diagnosis and therapy. Among the “celebrities” are CD20, a target for lymphoma therapeutic antibodies which earns $2 billion annually (and makes a significant difference to lymphoma patients), and CD4, the molecule used by the human immunodeficiency virus (HIV) as an entry portal into cells of the immune system. This short review provides a background to the CD molecules and antibodies against them, and summarizes research, diagnostic, and therapeutic applications of antibodies against these molecules. PMID:17380197

  18. Impaired chemotactic responses of bronchoalveolar leukocytes in experimental pneumoconiosis.

    PubMed

    Donaldson, K; Brown, G M; Brown, D M; Slight, J; Robertson, M D; Davis, J M

    1990-01-01

    Rats were exposed to clouds of the following pneumoconiotic dusts: quartz, coal-mine dust, and chrysotile asbestos at 10 or 50 mg/m3 for 8, 32, and 75 days; for comparison, rats were also exposed to the non-pathogenic dust titanium dioxide (TiO2). The bronchoalveolar leukocytes (macrophages and neutrophils) from dust-exposed and control rats were obtained by lavage and tested for their ability to migrate toward zymosan-activated serum. Varying amounts of neutrophils were present depending on the ability of the dust to cause inflammation and the length of exposure. There was a marked loss of chemotactic ability in leukocytes from rats inhaling the pneumoconiotic dusts compared with controls; TiO2-exposed leukocytes had some impairment of chemotaxis, but this was substantially less than that found with the pneumoconiotic dusts. The loss of chemotactic activity did not correlate with the percentage of neutrophils in the lavage cells except when there were very high levels of neutrophils, and there was substantial impairment of chemotaxis with negligible numbers of neutrophils, showing that macrophage chemotaxis was impaired. A phagocytic burden within the leucocytes was not sufficient alone to inhibit chemotaxis, nor was the loss of chemotactic activity due to occupied receptors, since incubation failed to restore chemotaxis. Loss to chemotactic activity by leukocytes from pneumoconiotic dust-exposed lung could be an important factor in the development of pneumoconiosis.

  19. Differential MSC activation leads to distinct mononuclear leukocyte binding mechanisms

    NASA Astrophysics Data System (ADS)

    Kota, Daniel J.; Dicarlo, Bryan; Hetz, Robert A.; Smith, Philippa; Cox, Charles S.; Olson, Scott D.

    2014-04-01

    Advances in the field of Multipotent Mesenchymal Stromal cell (MSC) biology have demonstrated that MSCs can improve disease outcome when `activated' to exert immunomodulatory effects. However, the precise mechanisms modulating MSC-immune cells interactions remain largely elusive. In here, we activated MSC based on a recent polarization paradigm, in which MSCs can be polarized towards a pro- or anti-inflammatory phenotype depending on the Toll-like receptor stimulated, to dissect the mechanisms through which MSCs physically interact with and modulate leukocytes in this context. Our data show that MSCs activated through the Toll-like receptor (TLR) 4 pathway increased VCAM-1 and ICAM-1 dependent binding of leukocytes. On the other hand, TLR3 stimulation strongly increases leukocytes affinity to MSC comparatively, through the formation of cable-like hyaluronic acid structures. In addition, TLR4 activation elicited secretion of pro-inflammatory mediators by MSCs, whereas TLR3-activated MSCs displayed a milder pro-inflammatory phenotype, similar to inactivated MSCs. However, the differently activated MSCs maintained their ability to suppress leukocyte activation at similar levels in our in vitro model, and this immunomodulatory property was shown here to be partially mediated by prostaglandin. These results reinforce the concept that alternate activation profiles control MSC responses and may impact the therapeutic use of MSCs.

  20. Leukocyte driven-decidual angiogenesis in early pregnancy.

    PubMed

    Lima, Patricia D A; Zhang, Jianhong; Dunk, Caroline; Lye, Stephen J; Croy, B Anne

    2014-11-01

    Successful pregnancy and long-term, post-natal maternal and offspring cardiac, vascular and metabolic health require key maternal cardiovascular adaptations over gestation. Within the pregnant decidualizing uterus, coordinated vascular, immunological and stromal cell changes occur. Considerable attention has been given to the roles of uterine natural killer (uNK) cells in initiating decidual spiral arterial remodeling, a process normally completed by mid-gestation in mice and in humans. However, leukocyte roles in much earlier, region specific, decidual vascular remodeling are now being defined. Interest in immune cell-promoted vascular remodeling is driven by vascular aberrations that are reported in human gestational complications such as infertility, recurrent spontaneous abortion, preeclampsia (PE) and fetal growth restriction. Appropriate maternal cardiovascular responses during pregnancy protect mothers and their children from later cardiovascular disease risk elevation. One of the earliest uterine responses to pregnancy in species with hemochorial placentation is stromal cell decidualization, which creates unique niches for angiogenesis and leukocyte recruitment. In early decidua basalis, the aspect of the implantation site that will cradle the developing placenta and provide the major blood vessels to support mature placental functions, leukocytes are greatly enriched and display specialized properties. UNK cells, the most abundant leukocyte subset in early decidua basalis, have angiogenic abilities and are essential for normal early decidual angiogenesis. The regulation of uNK cells and their roles in determining maternal and progeny cardiovascular health over pregnancy and postpartum are discussed. PMID:25066422

  1. Beta-adrenoceptor changes in mononuclear leukocytes during pregnancy.

    PubMed

    Nwosu, U C; Rice, P J

    1995-06-01

    Leukocyte beta 2-adrenoceptors mirror similar receptors in the uterus. This study examined changes in beta 2-adrenoceptors and in cAMP production during pregnancy using peripheral mononuclear leukocytes isolated from 17 pregnant women and 5 nonpregnant controls. beta 2-Adrenoceptor density was determined by 125I-pindolol binding. cAMP production under basal and stimulated (10 microM isoproterenol) conditions was determined by radioimmunoassay. Groups were compared by unpaired t test. There was a nonsignificant decrease in the density of beta-adrenoceptors during pregnancy. While basal cAMP production was unchanged during pregnancy, stimulated cAMP production was decreased (44% of control, P < 0.001; 95% CI 33%-56%). Stimulated cAMP production per receptor was lower in leukocytes from pregnant women and was not a constant relationship, but was increased markedly in leukocytes having fewer than 400 beta-adrenoceptor sites per cell. There are significant changes in the coupling of beta-adrenoceptors to cAMP production during pregnancy without changes in beta-receptor density, affinity, or basal cAMP production.

  2. Uptake of radiolabeled leukocytes in prosthetic graft infection

    SciTech Connect

    Serota, A.I.; Williams, R.A.; Rose, J.G.; Wilson, S.E.

    1981-07-01

    The utility of radionuclide labeled leukocytes in the demonstration of infection within vascular prostheses was examined. The infrarenal aorta was replaced with a 3 cm Dacron graft in 12 dogs. On the third postoperative day, six of the animals received an intravenous injection of 10(8) Staphylococcus aureus. Labeled leukocyte scans were performed at postoperative days one and three, and then weekly for 8 weeks with indium-111 and technetium-99 labeled autologous leukocytes. When scans showed focal uptake of isotope in the area of prosthetic material, the grafts were aseptically excised and cultured on mannitol-salt agar. Both control and infected animals had retroperitoneal isotope activity in the immediate postoperative period that disappeared by the end of the first week. By the eighth postoperative week, all of the animals that received the bacteremic challenge had both radionuclide concentration in the region of the vascular prosthesis and S. aureus cultured subsequently from the perigraft tissues. None of the control animals had either radionuclide or bacteriologic evidence of infection at the eighth postoperative week. The radiolabeled leukocyte scan is a highly sensitive and specific technique, clinically applicable for the diagnosis of vascular prosthetic infections.

  3. Characterization of the human immunoglobulin G Fc-binding activity in Prevotella intermedia.

    PubMed Central

    Labbé, S; Grenier, D

    1995-01-01

    Many pathogenic bacteria possess cell surface receptors which can bind immunoglobulins via the Fc portion. The aim of this study was to characterize the human immunoglobulin G (IgG) Fc-binding activity of Prevotella intermedia, a suspected etiologic agent of adult chronic periodontitis. The Fc-binding activity of P. intermedia on whole cells and on extracellular vesicles was demonstrated. Incubation of P. intermedia cells in the presence of Zwittergent 3-14 allowed complete solubilization of the Fc receptor from the cell surface. This cell envelope extract was thus used to characterize the Fc-binding activity. A microtiter plate assay using alkaline phosphatase-labeled Fc fragments showed that preincubation of the cell envelope extract with human IgG, human IgG Fc fragments, or human serum completely inhibited the Fc-binding activity. Partial inhibition was obtained with human IgG F(ab')2 fragments, whereas no inhibition occurred following preincubation with human IgA, carbohydrates, and selected proteins. Preincubation of the cell envelope extract with IgG from a variety of animals demonstrated that rabbit, mouse, rat, goat, and sheep IgG did not inhibit Fc-binding activity, whereas cow, pig, and dog IgG partially inhibited Fc-binding activity. A strong inhibition comparable to that obtained with human IgG was noted with monkey IgG. The Fc receptor of P. intermedia is thus different from the six types previously reported in other nonoral bacteria. Polyacrylamide gel electrophoresis and Western blotting (immunoblotting) analysis of the cell envelope extract revealed a major band with a molecular mass of approximately 65 kDa which reacted with peroxidase-labeled human IgG Fe fragments. Transmission electron microscopy showed a uniform distribution of the Fc receptor on the bacterial surface, as revealed by gold labeling. The Fc-binding activity demonstrated in this study may act as an additional virulence factor for P. intermedia by reducing IgG reactions with the

  4. In vivo compartmental analysis of leukocytes in mouse lungs.

    PubMed

    Patel, Brijesh V; Tatham, Kate C; Wilson, Michael R; O'Dea, Kieran P; Takata, Masao

    2015-10-01

    The lung has a unique structure consisting of three functionally different compartments (alveolar, interstitial, and vascular) situated in an extreme proximity. Current methods to localize lung leukocytes using bronchoalveolar lavage and/or lung perfusion have significant limitations for determination of location and phenotype of leukocytes. Here we present a novel method using in vivo antibody labeling to enable accurate compartmental localization/quantification and phenotyping of mouse lung leukocytes. Anesthetized C57BL/6 mice received combined in vivo intravenous and intratracheal labeling with fluorophore-conjugated anti-CD45 antibodies, and lung single-cell suspensions were analyzed by flow cytometry. The combined in vivo intravenous and intratracheal CD45 labeling enabled robust separation of the alveolar, interstitial, and vascular compartments of the lung. In naive mice, the alveolar compartment consisted predominantly of resident alveolar macrophages. The interstitial compartment, gated by events negative for both intratracheal and intravenous CD45 staining, showed two conventional dendritic cell populations, as well as a Ly6C(lo) monocyte population. Expression levels of MHCII on these interstitial monocytes were much higher than on the vascular Ly6C(lo) monocyte populations. In mice exposed to acid aspiration-induced lung injury, this protocol also clearly distinguished the three lung compartments showing the dynamic trafficking of neutrophils and exudative monocytes across the lung compartments during inflammation and resolution. This simple in vivo dual-labeling technique substantially increases the accuracy and depth of lung flow cytometric analysis, facilitates a more comprehensive examination of lung leukocyte pools, and enables the investigation of previously poorly defined "interstitial" leukocyte populations during models of inflammatory lung diseases.

  5. Human platelet Fc (IgG) receptor and its modulation

    SciTech Connect

    King, M.; McDermott, P.; Schreiber, A.D.

    1986-03-01

    The authors demonstrated that IgG oligomers bind to washed human platelets (P) by an Fc dependent process optimally at low ionic strength (/sup +/0.07) in 3 hrs at 4/sup 0/, while IgG monomer binds immeasurably. The authors studied the modulation of this Fc (IgG) binding site (Rc) on P by measuring /sup 125/I-IgG trimer binding to P at equilibrium and assessing Rc number of affinity. At ..mu.. = 0.07, P expressed 2 fold more Rc than at ..mu.. = 0.15, without a change in affinity; this effect was reversed upon re-exposure of P to ionic strength ..mu.. = 0.15. Equal numbers and affinities of Rc were observed in the presence of either 2mM EDTA, 2 mM EGTA or 2 mM EGTA + 2 mM Mg/sup + +/. Cytochalasin B (10 ..mu..g/ml) did not alter Rc (4987 sites/P, Ka = 0.9 x 10/sup 7/M/sup -1/ vs 5098 sites/P, Ka = 1.1 x 10/sup 7/M/sup -1/). Incubation with P alloreactive plasma at a concentration which depleted 33% of plasma C3, decreased Rc by 50%. However, activation of P by 10..mu..M ADP with Ca/sup + +/, Mg/sup + +/ and 100 ..mu..g/ml fibrinogen did not affect Rc number of affinity (2825 sites/P, Ka = 1.1 x 10/sup 7/M/sup -1/ vs 2551 sites/P, Ka = 0.9 x 10/sup 7/M/sup -1/). Thrombin (0.01 - 10 U/ml) also did not alter the number or affinity of Rc. P from 2 patients with thrombastenia expressed normal Rc number and affinity. Binding of IgG trimer to P occurs independent of actin filament interaction, Mg/sup + +/, modulation of P by ADP or thrombin, and of GPIIb/IIIa orGPIIb/IIIa-fibrogen interaction.

  6. Two-step model of leukocyte-endothelial cell interaction in inflammation: distinct roles for LECAM-1 and the leukocyte beta 2 integrins in vivo.

    PubMed Central

    von Andrian, U H; Chambers, J D; McEvoy, L M; Bargatze, R F; Arfors, K E; Butcher, E C

    1991-01-01

    The lectin homing receptor LECAM-1 (LAM-1, Leu8) and the beta 2 integrins, particularly Mac-1 (CD11b/CD18), participate in leukocyte-endothelial cell interactions in inflammation. LECAM-1 is rapidly shed while Mac-1 expression is dramatically increased upon neutrophil activation, suggesting functionally distinct roles for these molecules. Using intravital video microscopy, we have compared the effect of antibodies against LECAM-1 and CD18 on leukocyte interactions with rabbit mesenteric venules. Anti-LECAM-1 monoclonal antibody and its Fab fragments inhibited initial reversible leukocyte rolling along the vascular wall. Anti-CD18 monoclonal antibody had no effect on rolling but prevented subsequent firm attachment of leukocytes to venular endothelium. These results support a two-step model of leukocyte-endothelial cell interactions: reversible rolling mediated in part by LECAM-1 facilitates leukocyte recruitment by the local microenvironment and precedes activation-dependent firm attachment involving beta 2 integrins. Images PMID:1715568

  7. The Fc and not CD4 Receptor Mediates Antibody Enhancement of HIV Infection in Human Cells

    NASA Astrophysics Data System (ADS)

    Homsy, Jacques; Meyer, Mia; Tateno, Masatoshi; Clarkson, Sarah; Levy, Jay A.

    1989-06-01

    Antibodies that enhance human immunodeficiency virus (HIV) infectivity have been found in the blood of infected individuals and in infected or immunized animals. These findings raise serious concern for the development of a safe vaccine against acquired immunodeficiency syndrome. To address the in vivo relevance and mechanism of this phenomenon, antibody-dependent enhancement of HIV infectivity in peripheral blood macrophages, lymphocytes, and human fibroblastoid cells was studied. Neither Leu3a, a monoclonal antibody directed against the CD4 receptor, nor soluble recombinant CD4 even at high concentrations prevented this enhancement. The addition of monoclonal antibody to the Fc receptor III (anti-FcRIII), but not of antibodies that react with FcRI or FcRII, inhibited HIV type 1 and HIV type 2 enhancement in peripheral blood macrophages. Although enhancement of HIV infection in CD4+ lymphocytes could not be blocked by anti-FcRIII, it was inhibited by the addition of human immunoglobulin G aggregates. The results indicate that the FcRIII receptor on human macrophages and possibly another Fc receptor on human CD4+ lymphocytes mediate antibody-dependent enhancement of HIV infectivity and that this phenomenon proceeds through a mechanism independent of the CD4 protein.

  8. Atomic resolution model of the antibody Fc interaction with the complement C1q component.

    PubMed

    Schneider, Sebastian; Zacharias, Martin

    2012-05-01

    The globular C1q heterotrimer is a subunit of the C1 complement factor. Binding of the C1q subunit to the constant (Fc) part of antibody molecules is a first step and key event of complement activation. Although three-dimensional structures of C1q and antibody Fc subunits have been determined experimentally no atomic resolution structure of the C1q-Fc complex is known so far. Based on systematic protein-protein docking searches and Molecular Dynamics simulations a structural model of the C1q-IgG1-Fc-binding geometry has been obtained. The structural model is compatible with available experimental data on the interaction between the two partner proteins. It predicts a binding geometry that involves mainly the B-subunit of the C1q-trimer and both subunits of the IgG1-Fc-dimer with small conformational adjustments with respect to the unbound partners to achieve high surface complementarity. In addition to several charge-charge and polar contacts in the rim region of the interface it also involves nonpolar contacts between the two proteins and is compatible with the carbohydrate moiety of the Fc subunit. The model for the complex structure provides a working model for rationalizing available biochemical data on this important interaction and can form the basis for the design of Fc variants with a greater capacity to activate the complement system for example on binding to cancer cells or other target structures.

  9. Human IgG Fc promotes expression, secretion and immunogenicity of enterovirus 71 VP1 protein.

    PubMed

    Xu, Juan; Zhang, Chunhua

    2016-05-01

    Enterovirus (EV71) can cause severe neurological diseases, but the underlying pathogenesis remains unclear. The capsid protein, viral protein 1 (VP1), plays a critical role in the pathogenicity of EV71. High level expression and secretion of VP1 protein are necessary for structure, function and immunogenicity in its natural conformation. In our previous studies, 5 codon-optimized VP1 DNA vaccines, including wt-VP1, tPA-VP1, VP1-d, VP1-hFc and VP1-mFc, were constructed and analyzed. They expressed VP1 protein, but the levels of secretion and immunogenicity of these VP1 constructs were significantly different (P<0.05). In this study, we further investigated the protein levels of these constructs and determined that all of these constructs expressed VP1 protein. The secretion level was increased by including a tPA leader sequence, which was further increased by fusing human IgG Fc (hFc) to VP1. VP1-hFc demonstrated the most potent immunogenicity in mice. Furthermore, hFc domain could be used to purify VP1-hFc protein for additional studies. PMID:27533931

  10. The FC-1D: The profitable alternative Flying Circus Commercial Aviation Group

    NASA Technical Reports Server (NTRS)

    Meza, Victor J.; Alvarez, Jaime; Harrington, Brook; Lujan, Michael A.; Mitlyng, David; Saroughian, Andy; Silva, Alex; Teale, Tim

    1994-01-01

    The FC-1D was designed as an advanced solution for a low cost commercial transport meeting or exceeding all of the 1993/1994 AIAA/Lockheed request for proposal requirements. The driving philosophy behind the design of the FC-1D was the reduction of airline direct operating costs. Every effort was made during the design process to have the customer in mind. The Flying Circus Commercial Aviation Group targeted reductions in drag, fuel consumption, manufacturing costs, and maintenance costs. Flying Circus emphasized cost reduction throughout the entire design program. Drag reduction was achieved by implementation of the aft nacelle wing configuration to reduce cruise drag and increase cruise speeds. To reduce induced drag, rather than increasing the wing span of the FC-1D, spiroids were included in the efficient wing design. Profile and friction drag are reduced by using riblets in place of paint around the fuselage and empennage of the FC-1D. Choosing a single aisle configuration enabled the Flying Circus to optimize the fuselage diameter. Thus, reducing fuselage drag while gaining high structural efficiency. To further reduce fuel consumption a weight reduction program was conducted through the use of composite materials. An additional quality of the FC-1D is its design for low cost manufacturing and assembly. As a result of this design attribute, the FC-1D will have fewer parts which reduces weight as well as maintenance and assembly costs. The FC-1D is affordable and effective, the apex of commercial transport design.

  11. The Src family kinases Hck, Fgr, and Lyn are critical for the generation of the in vivo inflammatory environment without a direct role in leukocyte recruitment

    PubMed Central

    Kovács, Miklós; Németh, Tamás; Jakus, Zoltán; Sitaru, Cassian; Simon, Edina; Futosi, Krisztina; Botz, Bálint; Helyes, Zsuzsanna; Lowell, Clifford A.

    2014-01-01

    Although Src family kinases participate in leukocyte function in vitro, such as integrin signal transduction, their role in inflammation in vivo is poorly understood. We show that Src family kinases play a critical role in myeloid cell–mediated in vivo inflammatory reactions. Mice lacking the Src family kinases Hck, Fgr, and Lyn in the hematopoietic compartment were completely protected from autoantibody-induced arthritis and skin blistering disease, as well as from the reverse passive Arthus reaction, with functional overlap between the three kinases. Though the overall phenotype resembled the leukocyte recruitment defect observed in β2 integrin–deficient (CD18−/−) mice, Hck−/−Fgr−/−Lyn−/− neutrophils and monocytes/macrophages had no cell-autonomous in vivo or in vitro migration defect. Instead, Src family kinases were required for the generation of the inflammatory environment in vivo and for the release of proinflammatory mediators from neutrophils and macrophages in vitro, likely due to their role in Fcγ receptor signal transduction. Our results suggest that infiltrating myeloid cells release proinflammatory chemokine, cytokine, and lipid mediators that attract further neutrophils and monocytes from the circulation in a CD18-dependent manner. Src family kinases are required for the generation of the inflammatory environment but not for the intrinsic migratory ability of myeloid cells. PMID:25225462

  12. A Novel Factor H-Fc Chimeric Immunotherapeutic Molecule against Neisseria gonorrhoeae.

    PubMed

    Shaughnessy, Jutamas; Gulati, Sunita; Agarwal, Sarika; Unemo, Magnus; Ohnishi, Makoto; Su, Xia-Hong; Monks, Brian G; Visintin, Alberto; Madico, Guillermo; Lewis, Lisa A; Golenbock, Douglas T; Reed, George W; Rice, Peter A; Ram, Sanjay

    2016-02-15

    Neisseria gonorrhoeae, the causative agent of the sexually transmitted infection gonorrhea, has developed resistance to almost every conventional antibiotic. There is an urgent need to develop novel therapies against gonorrhea. Many pathogens, including N. gonorrhoeae, bind the complement inhibitor factor H (FH) to evade complement-dependent killing. Sialylation of gonococcal lipooligosaccharide, as occurs in vivo, augments binding of human FH through its domains 18-20 (FH18-20). We explored the use of fusing FH18-20 with IgG Fc (FH18-20/Fc) to create a novel anti-infective immunotherapeutic. FH18-20 also binds to select host glycosaminoglycans to limit unwanted complement activation on host cells. To identify mutation(s) in FH18-20 that eliminated complement activation on host cells, yet maintained binding to N. gonorrhoeae, we created four mutations in domains 19 or 20 described in atypical hemolytic uremic syndrome that prevented binding of mutated fH to human erythrocytes. One of the mutant proteins (D to G at position 1119 in domain 19; FHD1119G/Fc) facilitated complement-dependent killing of gonococci similar to unmodified FH18-20/Fc but, unlike FH18-20/Fc, did not lyse human erythrocytes. FHD1119G/Fc bound to all (100%) of 15 sialylated clinical N. gonorrhoeae isolates tested (including three contemporary ceftriaxone-resistant strains), mediated complement-dependent killing of 10 of 15 (67%) strains, and enhanced C3 deposition (≥10-fold above baseline levels) on each of the five isolates not directly killed by complement. FHD1119G/Fc facilitated opsonophagocytic killing of a serum-resistant strain by human polymorphonuclear neutrophils. FHD1119G/Fc administered intravaginally significantly reduced the duration and burden of gonococcal infection in the mouse vaginal colonization model. FHD1119G/Fc represents a novel immunotherapeutic against multidrug-resistant N. gonorrhoeae. PMID:26773149

  13. Characterization of cetuximab Fc/2 dimers by off-line CZE-MS.

    PubMed

    François, Yannis-Nicolas; Biacchi, Michael; Said, Nassur; Renard, Charly; Beck, Alain; Gahoual, Rabah; Leize-Wagner, Emmanuelle

    2016-02-18

    Monoclonal antibody (mAb) therapeutics attract the largest concern due to their strong therapeutic potency and specificity. The Fc region of mAbs is common to many new biotherapeutics as biosimilar, antibody drug conjugate or fusion protein. Fc region has consequences for Fc-mediated effector functions that might be desirable for therapeutic applications. As a consequence, there is a continuous need for improvement of analytical methods to enable fast and accurate characterization of biotherapeutics. Capillary zone electrophoresis-Mass spectrometry couplings (CZE-MS) appear really attractive methods for the characterization of biological samples. In this report, we used CZE-MS systems developed in house and native MS infusion to allow precise middle-up characterization of Fc/2 variant of cetuximab. Molecular weights were measured for three Fc/2 charge variants detected in the CZE separation of cetuximab subunits. Two Fc/2 C-terminal lysine variants were identified and separated. As the aim is to understand the presence of three peaks in the CZE separation for two Fc/2 subunits, we developed a strategy using CZE-UV/MALDI-MS and CZE-UV/ESI-MS to evaluate the role of N-glycosylation and C-terminal lysine truncation on the CZE separation. The chemical structure of N-glycosylation expressed on the Fc region of cetuximab does not influence CZE separation while C-terminal lysine is significantly influencing separation. In addition, native MS infusion demonstrated the characterization of Fc/2 dimers at pH 5.7 and 6.8 and the first separation of these dimers using CZE-MS. PMID:26826699

  14. A Novel Factor H-Fc Chimeric Immunotherapeutic Molecule against Neisseria gonorrhoeae.

    PubMed

    Shaughnessy, Jutamas; Gulati, Sunita; Agarwal, Sarika; Unemo, Magnus; Ohnishi, Makoto; Su, Xia-Hong; Monks, Brian G; Visintin, Alberto; Madico, Guillermo; Lewis, Lisa A; Golenbock, Douglas T; Reed, George W; Rice, Peter A; Ram, Sanjay

    2016-02-15

    Neisseria gonorrhoeae, the causative agent of the sexually transmitted infection gonorrhea, has developed resistance to almost every conventional antibiotic. There is an urgent need to develop novel therapies against gonorrhea. Many pathogens, including N. gonorrhoeae, bind the complement inhibitor factor H (FH) to evade complement-dependent killing. Sialylation of gonococcal lipooligosaccharide, as occurs in vivo, augments binding of human FH through its domains 18-20 (FH18-20). We explored the use of fusing FH18-20 with IgG Fc (FH18-20/Fc) to create a novel anti-infective immunotherapeutic. FH18-20 also binds to select host glycosaminoglycans to limit unwanted complement activation on host cells. To identify mutation(s) in FH18-20 that eliminated complement activation on host cells, yet maintained binding to N. gonorrhoeae, we created four mutations in domains 19 or 20 described in atypical hemolytic uremic syndrome that prevented binding of mutated fH to human erythrocytes. One of the mutant proteins (D to G at position 1119 in domain 19; FHD1119G/Fc) facilitated complement-dependent killing of gonococci similar to unmodified FH18-20/Fc but, unlike FH18-20/Fc, did not lyse human erythrocytes. FHD1119G/Fc bound to all (100%) of 15 sialylated clinical N. gonorrhoeae isolates tested (including three contemporary ceftriaxone-resistant strains), mediated complement-dependent killing of 10 of 15 (67%) strains, and enhanced C3 deposition (≥10-fold above baseline levels) on each of the five isolates not directly killed by complement. FHD1119G/Fc facilitated opsonophagocytic killing of a serum-resistant strain by human polymorphonuclear neutrophils. FHD1119G/Fc administered intravaginally significantly reduced the duration and burden of gonococcal infection in the mouse vaginal colonization model. FHD1119G/Fc represents a novel immunotherapeutic against multidrug-resistant N. gonorrhoeae.

  15. Stereotactic radiosurgery - Gamma Knife

    MedlinePlus

    ... Gamma Knife; Gamma Knife radiosurgery; Non-invasive neurosugery; Epilepsy - Gamma Knife ... problems ( arteriovenous malformation , arteriovenous fistula ) Some types of epilepsy Trigeminal neuralgia (severe nerve pain of the face) ...

  16. Geometry and microwave rotational spectrum of the FC16O18O• radical.

    PubMed

    Koucký, Jan; Kania, Patrik; Uhlíková, Tereza; Kolesniková, Lucie; Beckers, Helmut; Willner, Helge; Urban, Stěpán

    2013-10-01

    The rotational spectrum of an asymmetrically substituted isotopologue of the fluoroformyloxyl radical FC(16)O(18)O(•) with resolved fine and hyperfine structures were measured and analyzed for the very first time. The molecular parameters of this radical obtained from the spectral analysis were processed along with the symmetrical isotopologues FC(16)O2(•) and FC(18)O2(•) and accurate substitution geometry was attained. In addition to those, coupled cluster quantum chemistry calculations were used to scale the experimental parameters, and in this manner, trustworthy values of the equilibrium and ground state geometries were derived.

  17. The FC7 AMC for generic DAQ & control applications in CMS

    NASA Astrophysics Data System (ADS)

    Pesaresi, M.; Barros Marin, M.; Hall, G.; Hansen, M.; Iles, G.; Rose, A.; Vasey, F.; Vichoudis, P.

    2015-03-01

    The FC7 is a flexible, μTCA compatible Advanced Mezzanine Card (AMC) for generic data acquisition/control applications. Built around the Xilinx Kintex-7 FPGA, the FC7 provides developers with a platform which has access to a large array of configurable I/O, primarily delivered from on-board FPGA Mezzanine Card (FMC) sockets. Targeting users of high-speed optical links in high energy physics experiments, the board is capable of driving and receiving links up to 10 Gbps. This paper presents test results from the first set of pre-production prototypes and reports on FC7 uses and applications towards upgrades in CMS.

  18. Fc receptors in antibody-dependent enhancement of viral infections.

    PubMed

    Taylor, Adam; Foo, Suan-Sin; Bruzzone, Roberto; Dinh, Luan Vu; King, Nicholas J C; Mahalingam, Suresh

    2015-11-01

    Sensitization of the humoral immune response to invading viruses and production of antiviral antibodies forms part of the host antiviral repertoire. Paradoxically, for a number of viral pathogens, under certain conditions, antibodies provide an attractive means of enhanced virus entry and replication in a number of cell types. Known as antibody-dependent enhancement (ADE) of infection, the phenomenon occurs when virus-antibody immunocomplexes interact with cells bearing complement or Fc receptors, promoting internalization of the virus and increasing infection. Frequently associated with exacerbation of viral disease, ADE of infection presents a major obstacle to the prevention of viral disease by vaccination and is thought to be partly responsible for the adverse effects of novel antiviral therapeutics such as intravenous immunoglobulins. There is a growing body of work examining the intracellular signaling pathways and epitopes responsible for mediating ADE, with a view to aiding rational design of antiviral strategies. With in vitro studies also confirming ADE as a feature of infection for a growing number of viruses, challenges remain in understanding the multilayered molecular mechanisms of ADE and its effect on viral pathogenesis. PMID:26497532

  19. Garcinielliptone FC: antiparasitic activity without cytotoxicity to mammalian cells.

    PubMed

    Silva, Ana P; Silva, Marcos P; Oliveira, Cristiano G; Monteiro, Daniela C; Pinto, Pedro L; Mendonça, Ronaldo Z; Costa Júnior, Joaquim S; Freitas, Rivelilson M; de Moraes, Josué

    2015-06-01

    Garcinielliptone FC (GFC) is a natural prenylated benzophenone found in the seeds of Platonia insignis Mart. (Clusiaceae), a native Brazilian plant. It has been chemically characterized and it is known that GFC has several biological activities such as antioxidant and vasorelaxant properties. In this study, we report the in vitro effect of GFC against the blood fluke Schistosoma mansoni, the parasite responsible for schistosomiasis mansoni. The anti-S. mansoni activity and cytotoxicity toward mammalian cells were determined for the compound. GFC⩾6.25 μM showed antischistosomal activity and confocal laser scanning microscopy analysis demonstrated several morphological alterations on the tegument of worms, and a correlation between viability and tegumental damage was observed. In addition, at sub-lethal concentrations of GFC (⩽3.125 μM), the number of S. mansoni eggs was reduced. More importantly, GFC exhibited no activity toward mammalian cells and, therefore, there is an appreciable selectivity of this compound against the helminths. In conclusion, these findings indicate the potential of GFC as an antiparasitic agent. PMID:25553916

  20. Combined glyco- and protein-Fc engineering simultaneously enhance cytotoxicity and half-life of a therapeutic antibody

    PubMed Central

    Monnet, Céline; Jorieux, Sylvie; Souyris, Nathalie; Zaki, Ouafa; Jacquet, Alexandra; Fournier, Nathalie; Crozet, Fabien; de Romeuf, Christophe; Bouayadi, Khalil; Urbain, Rémi; Behrens, Christian K; Mondon, Philippe; Fontayne, Alexandre

    2014-01-01

    While glyco-engineered monoclonal antibodies (mAbs) with improved antibody-dependent cell-mediated cytotoxicity (ADCC) are reaching the market, extensive efforts have also been made to improve their pharmacokinetic properties to generate biologically superior molecules. Most therapeutic mAbs are human or humanized IgG molecules whose half-life is dependent on the neonatal Fc receptor FcRn. FcRn reduces IgG catabolism by binding to the Fc domain of endocytosed IgG in acidic lysosomal compartments, allowing them to be recycled into the blood. Fc-engineered mAbs with increased FcRn affinity resulted in longer in vivo half-life in animal models, but also in healthy humans. These Fc-engineered mAbs were obtained by alanine scanning, directed mutagenesis or in silico approach of the FcRn binding site. In our approach, we applied a random mutagenesis technology (MutaGenTM) to generate mutations evenly distributed over the whole Fc sequence of human IgG1. IgG variants with improved FcRn-binding were then isolated from these Fc-libraries using a pH-dependent phage display selection process. Two successive rounds of mutagenesis and selection were performed to identify several mutations that dramatically improve FcRn binding. Notably, many of these mutations were unpredictable by rational design as they were located distantly from the FcRn binding site, validating our random molecular approach. When produced on the EMABling® platform allowing effector function increase, our IgG variants retained both higher ADCC and higher FcRn binding. Moreover, these IgG variants exhibited longer half-life in human FcRn transgenic mice. These results clearly demonstrate that glyco-engineering to improve cytotoxicity and protein-engineering to increase half-life can be combined to further optimize therapeutic mAbs. PMID:24492301

  1. [In vitro transfer of immunity against PPD with dialyzable extract of leukocytes from human colostrum].

    PubMed

    Martínez-Cairo Cueto, S; Alasio-Chávez, C; Dávila Velázquez, J R

    1992-01-01

    The aim of this study is to demonstrate the transference of PPD hypersensibility in an in vitro model, with dialysable colostral leukocyte extract (DCLE) of PPD+ and PPD-mothers, through measurements of leukocyte migration inhibition factor activity (LIF) from blood obtained of the umbilical cord of newborns from PPD+ mothers. The results show that DCLE PPD+ incubated with leukocytes of newborns from PPD- mothers had inhibition of leukocyte migration compared with migration of leukocytes incubated with DCLE PPD-. These results suggest that in this in vitro model, DCLE transfers hypersensibility to PPD. PMID:1492196

  2. Metabolism of L-Thyroxine by Phagocytosing Human Leukocytes

    PubMed Central

    Woeber, Kenneth A.; Ingbar, Sidney H.

    1973-01-01

    Intact normal human leukocytes deiodinated L-thyroxine (T4) with the generation of inorganic iodide, chromatographically immobile origin material, and small quantities of L-triiodothyronine (T3). When phagocytosis was induced in the leukocytes through the addition of zymosan particles that had been opsonized by coating with plasma, T4-deiodination was greatly stimulated. In addition to the stimulation of T4-deiodination, the accumulation by the leukocytes of undegraded T4 was increased. Anoxia, which has previously been shown not to interfere with phagocytosis, did not prevent the increased cellular accumulation of T4 that phagocytosis induced, but virtually abolished T4-deiodination. On the other hand, calcium, which has previously been shown to be required for optimal phagocytosis, was required for the increase in both the cellular accumulation and deiodination of T4 that phagocytosis induced. Phospholipase-C, which has previously been shown to induce a metabolic burst that mimics that induced by phagocytosis, did not increase the cellular accumulation or deiodination of T4. On the other hand, colchicine, which has previously been shown to depress the metabolic burst that accompanies phagocytosis, did not prevent the increase in either the cellular accumulation or deiodination of T4 that phagocytosis induced. Thus, increased accumulation of T4 by the leukocytes during phagocytosis appears to be the primary factor responsible for the stimulation of deiodination that phagocytosis induces. The increased accumulation of T4 did not appear to be owing to engulfment of suspending medium surrounding the particles or to binding of T4 to the particles themselves. In addition to the enhanced cellular accumulation, other factors related to the metabolic burst that accompanies phagocytosis might also be involved in the stimulation of T4-deiodination. In leukocytes from two patients with chronic granulomatous disease, a disorder in which phagocytosis appears to occur normally

  3. Reactivity of monoclonal antibody FC-2.15 against drug resistant breast cancer cells. Additive cytotoxicity of adriamycin and taxol with FC-2.15.

    PubMed

    Ballaré, C; Portela, P; Schiaffi, J; Yomha, R; Mordoh, J

    1998-01-01

    Monoclonal antibody (MAb) FC-2.15 recognizes Lewis x antigen (Le(x)-Ag) expressed on the cell surface of most human breast cancer cells. FC-2.15 displays important human complement (C')-mediated cytotoxicity (CMC) against its target cells. In this study the reactivity of FC-2.15 against drug resistant-breast cancer cells was investigated, as well as the possibility to combine the antitumor activities of this MAb with adriamycin (Adr) or taxol. Since resistant clones with altered expression of tumor-associated antigens usually emerge after chemotherapy, the expression of Le(x)-Ag was analyzed in Adr(R) MCF-7 breast cancer cells (Adr resistant subline) and in tumor samples from nine patients with locally advanced breast carcinoma who were treated with FEC chemotherapy. A flow cytometry assay showed that most of Adr(R) MCF-7 cells, as well as wild type (WT) cells, expressed Le(x)-Ag; however, the Le(x) epitope is probably bound to different backbones in these cells. When the cytotoxic ability of FC-2.15 against WT and Adr(R) MCF-7 cells was compared, it was found that a 90 min treatment with FC-2.15 plus C' induced similar CMC against both cell lines. An important cytolysis was obtained at 5 microg/ml FC-2.15, reaching a plateau at 25 microg/ml, at which cell population was diminished to 21.1% for WT and 27.9 for Adr(R) MCF-7 cells. Regarding human tumors, Le(x)-Ag expression was evaluated in samples obtained before and in most cases after chemotherapy, and it could be observed that: 1) before treatment, tumor samples from all patients analyzed (responders and non-responders to chemotherapy) were FC-2.15-positive; 2) the presence of Le(x)-Ag was not modified after treatment. The combined action of Adr or taxol with FC-2.15 was then evaluated. WT and Adr(R) MCF-7 cells were cultured with Adr or taxol followed by an incubation with different FC-2.15 concentrations plus C'. When the effect of Adr alone was determined, ID50 were 1 x 10(-7) M for WT and 4.2 x 10(-5) M for

  4. Combined bone scintigraphy and indium-111 leukocyte scans in neuropathic foot disease

    SciTech Connect

    Schauwecker, D.S.; Park, H.M.; Burt, R.W.; Mock, B.H.; Wellman, H.N.

    1988-10-01

    It is difficult to diagnose osteomyelitis in the presence of neurotrophic osteoarthropathy. We performed combined (99mTc)MDP bone scans and indium-111 (111In) leukocyte studies on 35 patients who had radiographic evidence of neuropathic foot disease and clinically suspected osteomyelitis. The (111In)leukocyte study determined if there was an infection and the bone scan provided the anatomic landmarks so that the infection could be localized to the bone or the adjacent soft tissue. Seventeen patients had osteomyelitis and all showed increased (111In)leukocyte activity localized to the bone, giving a sensitivity of 100%. Among the 18 patients without osteomyelitis, eight had no accumulation of (111In)leukocytes, seven had the (111In)leukocyte activity correctly localized to the soft tissue, two had (111In)leukocyte activity mistakenly attributed to the bone, and one had (111In)leukocyte accumulation in a proven neuroma which was mistakenly attributed to bone. These three false-positive results for osteomyelitis reduced the specificity to 83%. Considering only the 27 patients with a positive (111In)leukocyte study, the combined bone scan and (111In)leukocyte study correctly localized the infection to the soft tissues or bone in 89%. Uninfected neurotrophic osteoarthropathy does not accumulate (111In)leukocytes. We found the combined bone scan and (111In) leukocyte study useful for the detection and localization of infection to soft tissue or bone in patients with neuropathic foot disease.

  5. Endothelial actin-binding proteins and actin dynamics in leukocyte transendothelial migration.

    PubMed

    Schnoor, Michael

    2015-04-15

    The endothelium is the first barrier that leukocytes have to overcome during recruitment to sites of inflamed tissues. The leukocyte extravasation cascade is a complex multistep process that requires the activation of various adhesion molecules and signaling pathways, as well as actin remodeling, in both leukocytes and endothelial cells. Endothelial adhesion molecules, such as E-selectin or ICAM-1, are connected to the actin cytoskeleton via actin-binding proteins (ABPs). Although the contribution of receptor-ligand interactions to leukocyte extravasation has been studied extensively, the contribution of endothelial ABPs to the regulation of leukocyte adhesion and transendothelial migration remains poorly understood. This review focuses on recently published evidence that endothelial ABPs, such as cortactin, myosin, or α-actinin, regulate leukocyte extravasation by controlling actin dynamics, biomechanical properties of endothelia, and signaling pathways, such as GTPase activation, during inflammation. Thus, ABPs may serve as targets for novel treatment strategies for disorders characterized by excessive leukocyte recruitment.

  6. The effects of space flight on polymorphonuclear leukocyte response experiment MA-032

    NASA Technical Reports Server (NTRS)

    Martin, R. R.

    1976-01-01

    In a series of studies performed at intervals from 30 day before flight to 30 days after recovery, blood samples were obtained from the three astronauts of the Apollo Soyuz Test Project and from eight control subjects. To determine the effects of space flight on polymorphonuclear leukocytes, tests were performed on blood samples obtained as quickly as possible after splashdown and on the day following recovery. The astronauts' inhalation of propellant gases and the inception of corticosteroid therapy 1 day after recovery provided an additional opportunity to investigate the possible effects of these factors on leukocyte function. Data were obtained during each time period on the total leukocyte count, differential count, leukocyte adhesion, leukocyte migration and chemotaxis, phagocytosis, and histochemical staining for leukocyte acid and alkaline phosphatase. These observations present a variety of in vitro correlates to white blood cell function within the body. Taken together, they serve as a reasonable approximation of the effects of space flight on leukocyte function.

  7. Transgenic Rabbits That Overexpress the Neonatal Fc Receptor (FcRn) Generate Higher Quantities and Improved Qualities of Anti-Thymocyte Globulin (ATG)

    PubMed Central

    Baranyi, Mária; Cervenak, Judit; Bender, Balázs; Kacskovics, Imre

    2013-01-01

    Immune suppression with rabbit anti-thymocyte globulin (rATG) is a well-established therapeutic concept for preventing host rejection of transplanted organs and graft versus host disease. Increasing the efficiency of rATG production by reducing the number of animals would be highly beneficial to lower cost and to improve quality standards. We have developed transgenic (Tg) mice and rabbits that overexpress the neonatal Fc receptor (FcRn) and have shown an augmented humoral immune response in these animals. To test whether our FcRn Tg rabbits produced rATG more efficiently, we immunized them and their New Zealand White controls with live Jurkat cells. By day 21 after immunization, Tg animals produced significantly, 1.5 times higher amount of total IgG compared to their wt littermates. Also, the binding efficiency of Tg sera to Jurkat cells and their complement-mediated cytotoxicity was significantly higher. The purified Tg IgG preparation contained 2.6 the amount of Jurkat specific IgG as the wt preparation analyzed by complement-mediated lysis, suggesting greater antigen-specific B cell activation in the Tg rabbits. To test this hypothesis, immunization with ovalbumin and human α1-antitrypsin was performed, resulting in significantly greater numbers of antigen-specific B-cells in the FcRn Tg rabbits as compared with wt controls. The shift towards significantly larger populations of antigen-specific B cells relative to the non-specific B cell pool is further corroborated by our previous findings in FcRn Tg mice. Consequently, our FcRn Tg rabbits have the potential to offer substantial qualitative and quantitative improvements for the production of rATG and other polyclonal or monoclonal antibodies. PMID:24194847

  8. Transgenic rabbits that overexpress the neonatal Fc receptor (FcRn) generate higher quantities and improved qualities of anti-thymocyte globulin (ATG).

    PubMed

    Baranyi, Mária; Cervenak, Judit; Bender, Balázs; Kacskovics, Imre

    2013-01-01

    Immune suppression with rabbit anti-thymocyte globulin (rATG) is a well-established therapeutic concept for preventing host rejection of transplanted organs and graft versus host disease. Increasing the efficiency of rATG production by reducing the number of animals would be highly beneficial to lower cost and to improve quality standards. We have developed transgenic (Tg) mice and rabbits that overexpress the neonatal Fc receptor (FcRn) and have shown an augmented humoral immune response in these animals. To test whether our FcRn Tg rabbits produced rATG more efficiently, we immunized them and their New Zealand White controls with live Jurkat cells. By day 21 after immunization, Tg animals produced significantly, 1.5 times higher amount of total IgG compared to their wt littermates. Also, the binding efficiency of Tg sera to Jurkat cells and their complement-mediated cytotoxicity was significantly higher. The purified Tg IgG preparation contained 2.6 the amount of Jurkat specific IgG as the wt preparation analyzed by complement-mediated lysis, suggesting greater antigen-specific B cell activation in the Tg rabbits. To test this hypothesis, immunization with ovalbumin and human α1-antitrypsin was performed, resulting in significantly greater numbers of antigen-specific B-cells in the FcRn Tg rabbits as compared with wt controls. The shift towards significantly larger populations of antigen-specific B cells relative to the non-specific B cell pool is further corroborated by our previous findings in FcRn Tg mice. Consequently, our FcRn Tg rabbits have the potential to offer substantial qualitative and quantitative improvements for the production of rATG and other polyclonal or monoclonal antibodies.

  9. Cloning, characterization, and expression analysis of the DEAD-box family genes, Fc-vasa and Fc-PL10a, in Chinese shrimp ( Fenneropenaeus chinensis)

    NASA Astrophysics Data System (ADS)

    Zhou, Qianru; Shao, Mingyu; Qin, Zhenkui; Kyoung, Ho Kang; Zhang, Zhifeng

    2010-01-01

    RNA helicases of the DEAD-box and related families are involved in various cellular processes including DNA replication, DNA repair, and RNA processing. However, the function of DEAD-box proteins in aquaculture species is poorly understood at molecular level. We obtained the full-length cDNA sequences of two genes encoding helicase-related proteins, Fc-vasa and Fc-PL10a, from the testes of Chinese shrimp, Fenneropenaeus chinensis. The two predicted amino acid sequences contain all the conserved motifs characterized by the DEAD-box family and several RGG repeats in the N-terminal regions. Homology and phylogenetic analyses indicate that they belong to the vasa and PL10 subfamilies. The three-dimensional structures of the two proteins were predicted with a homology modeling approach. Both core proteins consist of two tandem RecA-like domains similar to those of the DEAD-box RNA helicase. Using reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR we found that Fc-vasa was expressed specifically in the adult gonads. Transcription decreased in the ovary but increased in the testis during gonadal development. Fc-PL10a expression was widely distributed in the tissues we examined. Using in situ hybridization, we demonstrated that the Fc-vasa transcript is localized to the cytoplasm of the spermatogonia and oocytes. Thus, our results suggest that Fc-vasa plays an important role in germ-line development, and has utility as a germ cell lineage marker which will help to generate new insight into the origin and differentiation of germ cells as well as the regulation of reproduction in F. chinensis.

  10. Impact of methionine oxidation in human IgG1 Fc on serum half-life of monoclonal antibodies.

    PubMed

    Wang, Weirong; Vlasak, Josef; Li, Yunsong; Pristatsky, Pavlo; Fang, Yulin; Pittman, Tamara; Roman, Jeanette; Wang, Yang; Prueksaritanont, Thomayant; Ionescu, Roxana

    2011-03-01

    IgG monoclonal antibodies (mAbs) consist of two Fab fragments and one Fc fragment. The Fab fragments contain the variable regions and are responsible for drug specificity (via antigen binding); the Fc fragment contains constant regions and is responsible for effector functions (via interactions with Fcγ receptors) and extended serum half-life (via interaction with the neonatal Fc receptor, FcRn). There are two conserved methionine (Met) residues located in the FcRn binding site of the Fc fragment. It has been shown previously that oxidation of these two Met residues decreases the binding affinity to FcRn. We have further evaluated the impact of Met oxidation on serum half-lives of two humanized IgG1 mAbs in transgenic mice with human FcRn. Variable oxidation levels were obtained by several procedures: exposure to an oxidizing agent, accumulation during extended refrigerated storage, or chromatographic separation. Our results show that Met oxidation can result in a significant reduction of the serum circulation half-life and the magnitude of the change correlates well with the extent of Met oxidation and changes in FcRn binding affinities. The relatively low levels of Met oxidation accumulated during 3 years of refrigerated storage had minimal impact on FcRn binding and no detectable impact on the serum half-life.

  11. Immune regulation by Fcα/μ receptor (CD351) on marginal zone B cells and follicular dendritic cells.

    PubMed

    Shibuya, Akira; Honda, Shin-ichiro

    2015-11-01

    Although both Fcα/μ receptor (Fcα/μR) and polymeric Ig receptor (poly-IgR) are Fc receptors for IgA and IgM and are functionally and genetically related, the expression profile of Fcα/μR is unique. Unlike poly-IgR, Fcα/μR is expressed on marginal zone (MZ) B cells and follicular dendritic cells, suggesting that Fcα/μR plays an important role in humoral immune responses. Fcα/μR mediates endocytosis of the IgM immune complex (IC). Recent research demonstrated that Fcα/μR downregulated retention of the IgM IC with a T-independent (TI) antigen on MZ B cells and follicular dendritic cells due to endocytosis of the IgM IC, suppressing germinal center formation, affinity maturation, and memory B-cell generation in response to TI antigen challenge. In addition, Fcα/μR physically associates with Toll-like receptor 4 (TLR4) and augments TLR4 oligomerization and signaling in MZ B cells upon lipopolysaccharide (LPS) challenge, leading to increased proinflammatory cytokine production by MZ B cells. Thus, Fcα/μR is a unique Fc receptor that is involved in humoral immune responses and inflammation. PMID:26497528

  12. BIMOLECULAR FLUORESCENCE COMPLEMENTATION (BiFC) ANALYSIS AS A PROBE OF PROTEIN INTERACTIONS IN LIVING CELLS

    PubMed Central

    Kerppola, Tom K.

    2009-01-01

    Protein interactions are a fundamental mechanism for the generation of biological regulatory specificity. The study of protein interactions in living cells is of particular significance because the interactions that occur in a particular cell depend on the full complement of proteins present in the cell and the external stimuli that influence the cell. Bimolecular fluorescence complementation (BiFC) analysis enables direct visualization of protein interactions in living cells. The BiFC assay is based on the association between two non-fluorescent fragments of a fluorescent protein when they are brought in proximity to each other by an interaction between proteins fused to the fragments. Numerous protein interactions have been visualized using the BiFC assay in many different cell types and organisms. The BiFC assay is technically straightforward and can be performed using standard molecular biology and cell culture reagents and a regular fluorescence microscope or flow cytometer. PMID:18573091

  13. 21 CFR 866.5530 - Immunoglobulin G (Fc fragment specific) immunological test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... immunoglobulin G (resulting from breakdown of immunoglobulin G antibodies) in urine, serum, and other body fluids. Measurement of immunoglobulin G Fc fragments aids in the diagnosis of plasma cell...

  14. Expression of recombinant human anti-TNF-α scFv-Fc in Arabidopsis thaliana seeds.

    PubMed

    Yao, N; Ai, L; Dong, Y Y; Liu, X M; Wang, D Z; Wang, N; Li, X W; Wang, F W; Li, Xk; Li, H Y; Jiang, C

    2016-01-01

    Recombinant human anti-tumor necrosis factor (TNF)-α scFv-Fc was expressed in TKO mutant Arabidopsis thaliana seeds using plant-specific codons. Immunoblotting using a human IgG1 antibody detected the expression of anti-TNF-α proteins in plants. Results from qRT-PCR analysis demonstrated that the time of harvest significantly affected the protein yield and quality. Our results indicate that the Phaseolus vulgaris β-phaseolin promoter directed anti-TNF-α scFv-Fc expression in A. thaliana seeds, with a maximum yield obtained at 20-days of development. Although the yield of anti-TNF-α scFv-Fc protein was not very high, accumulation of recombinant proteins in seeds is an attractive and simple method that can be used to purify biologically active anti-TNF-α scFv-Fc. PMID:27420937

  15. Influence of cadmium on isolated peritoneal macrophage populations: cadmium inhibits Fc receptor internalization

    SciTech Connect

    Cook, G.B.

    1985-01-01

    In vitro experiments were performed to examine the effect of cadmium on adherent phagocytic cell populations. The authors were able to demonstrate, in vitro, a phagocytic defect that was originally observed in an in vivo system. Using in vitro methodologies, cadmium was found to inhibit opsonin-dependent but not opsonin-independent phagocytosis in two different populations of macrophages. The receptors through which the opsonized /sup 51/Cr-ElgG were internalized were characterized as Fc receptors. They were able to demonstrate that cadmium could reversibly inhibit internalization of Fc receptors. This mechanism, rather than an alteration of the receptors' binding capabilities, was responsible for the observed inhibition of Fc mediated (opsonin-dependent) phagocytosis in both populations of macrophages tested. The defect was not specific for cadmium per se. Zinc treatment caused a similar inhibition of Fc receptor mediated phagocytosis.

  16. Signaling networks regulating leukocyte podosome dynamics and function

    PubMed Central

    Dovas, Athanassios; Cox, Dianne

    2011-01-01

    Podosomes are ventral adhesion structures prominent in cells of the myeloid lineage. A common aspect of these cells is that they are highly motile and are required to traverse multiple tissue barriers in order to perform their functions. Recently podosomes have gathered attention from researchers as important cellular structures that can influence cell adhesion, motility and matrix remodeling. Adhesive and soluble ligands act via transmembrane receptors and propagate signals to the leukocyte cytoskeleton via small G proteins of the Rho family, tyrosine kinases and scaffold proteins and are able to induce podosome formation and rearrangements. Manipulation of the signals that regulate podosome formation and dynamics can therefore be a strategy to interfere with leukocyte functions in a multitude of pathological settings, such as infections, atherosclerosis and arthritis. Here, we review the major signaling molecules that act in the formation and regulation of podosomes. PMID:21342664

  17. Derivation of Cinnamon Blocks Leukocyte Attachment by Interacting with Sialosides.

    PubMed

    Lin, Wei-Ling; Guu, Shih-Yun; Tsai, Chan-Chuan; Prakash, Ekambaranellore; Viswaraman, Mohan; Chen, Hsing-Bao; Chang, Chuan-Fa

    2015-01-01

    Molecules derived from cinnamon have demonstrated diverse pharmacological activities against infectious pathogens, diabetes and inflammatory diseases. This study aims to evaluate the effect of the cinnamon-derived molecule IND02 on the adhesion of leukocytes to host cells. The anti-inflammatory ability of IND02, a pentameric procyanidin type A polyphenol polymer isolated from cinnamon alcohol extract, was examined. Pretreatment with IND02 significantly reduced the attachment of THP-1 cells or neutrophils to TNF-α-activated HUVECs or E-selectin/ICAM-1, respectively. IND02 also reduced the binding of E-, L- and P-selectins with sialosides. Furthermore, IND02 could agglutinate human red blood cells (RBC), and the agglutination could be disrupted by sialylated glycoprotein. Our findings demonstrate that IND02, a cinnamon-derived compound, can interact with sialosides and block the binding of selectins and leukocytes with sialic acids.

  18. Effect of antenatal dexamethasone on neonatal leukocyte count.

    PubMed

    Zachman, R D; Bauer, C R; Boehm, J; Korones, S B; Rigatto, H; Rao, A V

    1988-01-01

    The leukocyte count and differential white blood cell count during the first hour of life was determined in 164 neonates born of mothers receiving antenatal steroids and compared to 171 neonates of mothers randomly assigned to a placebo group. A leukemoid reaction (greater than 40,000 WBC/mm3) was seen only once each in the neonates born of placebo or steroid treated mothers. In addition, maternal steroid treatment had no general effect, except in a small subgroup of neonates born 3 to 7 days after the mother had been treated with 20 mg dexamethasone, where the total leukocyte and the absolute neutrophil counts were higher than the placebo group and other subgroups. PMID:3057139

  19. Derivation of Cinnamon Blocks Leukocyte Attachment by Interacting with Sialosides

    PubMed Central

    Lin, Wei-Ling; Guu, Shih-Yun; Tsai, Chan-Chuan; Prakash, Ekambaranellore; Viswaraman, Mohan; Chen, Hsing-Bao; Chang, Chuan-Fa

    2015-01-01

    Molecules derived from cinnamon have demonstrated diverse pharmacological activities against infectious pathogens, diabetes and inflammatory diseases. This study aims to evaluate the effect of the cinnamon-derived molecule IND02 on the adhesion of leukocytes to host cells. The anti-inflammatory ability of IND02, a pentameric procyanidin type A polyphenol polymer isolated from cinnamon alcohol extract, was examined. Pretreatment with IND02 significantly reduced the attachment of THP-1 cells or neutrophils to TNF-α-activated HUVECs or E-selectin/ICAM-1, respectively. IND02 also reduced the binding of E-, L- and P-selectins with sialosides. Furthermore, IND02 could agglutinate human red blood cells (RBC), and the agglutination could be disrupted by sialylated glycoprotein. Our findings demonstrate that IND02, a cinnamon-derived compound, can interact with sialosides and block the binding of selectins and leukocytes with sialic acids. PMID:26076445

  20. Leukocyte-endothelium interaction: measurement by laser tweezers force spectroscopy.

    PubMed

    Wang, Shi-Kang; Chiu, Jeng-Jiann; Lee, Ming-Rou; Chou, Shih-Chin; Chen, Li-Jing; Hwang, Ned H C

    2006-09-01

    Leukocyte adhesion to vascular endothelium is an initial step of many inflammatory diseases. Although the atomic force microscopy (AFM) measurements of leukocyte-endothelial interaction have been recently introduced. with cell adhesion force unbinding curves (CAFUC). We obtained pico-Newton force in the initial interaction between a single living THP-1 cell and HUVEC monolayer using a custom-built laser tweezers (LT) system. The measured quantities included the non-linear force-distance relationship, and the effect of yielding in cell detachment. It is possible to introduce a time scale into the LT cell-detachment experiments for further exploration and more detailed information on the viscoelastic properties of living cells. PMID:16960761

  1. Altering Antibody-Drug Conjugate Binding to the Neonatal Fc Receptor Impacts Efficacy and Tolerability.

    PubMed

    Hamblett, Kevin J; Le, Tiep; Rock, Brooke M; Rock, Dan A; Siu, Sophia; Huard, Justin N; Conner, Kip P; Milburn, Robert R; O'Neill, Jason W; Tometsko, Mark E; Fanslow, William C

    2016-07-01

    Antibody-drug conjugates (ADC) rely on the target-binding specificity of an antibody to selectively deliver potent drugs to cancer cells. IgG antibody half-life is regulated by neonatal Fc receptor (FcRn) binding. Histidine 435 of human IgG was mutated to alanine (H435A) to explore the effect of FcRn binding on the pharmacokinetics, efficacy, and tolerability of two separate maytansine-based ADC pairs with noncleavable linkers, (c-DM1 and c-H435A-DM1) and (7v-Cys-may and 7v-H435A-Cys-may). The in vitro cell-killing potency of each pair of ADCs was similar, demonstrating that H435A showed no measurable impact on ADC bioactivity. The H435A mutant antibodies showed no detectable binding to human or mouse FcRn in vitro, whereas their counterpart wild-type IgG ADCs were found to bind to FcRn at pH = 6.0. In xenograft bearing SCID mice expressing mouse FcRn, the AUC of 7v-Cys-may was 1.6-fold higher than that of 7v-H435A-may, yet the observed efficacy was similar. More severe thrombocytopenia was observed with 7v-H435A-Cys-may as compared to 7v-Cys-may at multiple dose levels. The AUC of c-DM1 was approximately 3-fold higher than that of c-H435A-DM1 in 786-0 xenograft bearing SCID mice, which led to a 3-fold difference in efficacy by dose. Murine FcRn knockout, human FcRn transgenic line 32 SCID animals bearing 786-0 xenografts showed an amplified exposure difference between c-DM1 and c-H435A-DM1 as compared to murine FcRn expressing SCID mice, leading to a 10-fold higher dose required for efficacy despite a 6-fold higher AUC of the c-H435A-DM1. The accelerated clearance observed for the noncleavable maytansine ADCs with the H435A FcRn mutation led to reduced efficacy at equivalent doses and exacerbation of clinical pathology parameters (decreased tolerability) at equivalent doses. The results show that reduced ADC clearance mediated by FcRn modulation can improve therapeutic index. PMID:27248573

  2. Fully Human Monoclonal Antibody Inhibitors of the Neonatal Fc Receptor Reduce Circulating IgG in Non-Human Primates

    PubMed Central

    Nixon, Andrew E.; Chen, Jie; Sexton, Daniel J.; Muruganandam, Arumugam; Bitonti, Alan J.; Dumont, Jennifer; Viswanathan, Malini; Martik, Diana; Wassaf, Dina; Mezo, Adam; Wood, Clive R.; Biedenkapp, Joseph C.; TenHoor, Chris

    2015-01-01

    The therapeutic management of antibody-mediated autoimmune disease typically involves immunosuppressant and immunomodulatory strategies. However, perturbing the fundamental role of the neonatal Fc receptor (FcRn) in salvaging IgG from lysosomal degradation provides a novel approach – depleting the body of pathogenic immunoglobulin by preventing IgG binding to FcRn and thereby increasing the rate of IgG catabolism. Herein, we describe the discovery and preclinical evaluation of fully human monoclonal IgG antibody inhibitors of FcRn. Using phage display, we identified several potent inhibitors of human-FcRn in which binding to FcRn is pH-independent, with over 1000-fold higher affinity for human-FcRn than human IgG-Fc at pH 7.4. FcRn antagonism in vivo using a human-FcRn knock-in transgenic mouse model caused enhanced catabolism of exogenously administered human IgG. In non-human primates, we observed reductions in endogenous circulating IgG of >60% with no changes in albumin, IgM, or IgA. FcRn antagonism did not disrupt the ability of non-human primates to mount IgM/IgG primary and secondary immune responses. Interestingly, the therapeutic anti-FcRn antibodies had a short serum half-life but caused a prolonged reduction in IgG levels. This may be explained by the high affinity of the antibodies to FcRn at both acidic and neutral pH. These results provide important preclinical proof of concept data in support of FcRn antagonism as a novel approach to the treatment of antibody-mediated autoimmune diseases. PMID:25954273

  3. Fully human monoclonal antibody inhibitors of the neonatal fc receptor reduce circulating IgG in non-human primates.

    PubMed

    Nixon, Andrew E; Chen, Jie; Sexton, Daniel J; Muruganandam, Arumugam; Bitonti, Alan J; Dumont, Jennifer; Viswanathan, Malini; Martik, Diana; Wassaf, Dina; Mezo, Adam; Wood, Clive R; Biedenkapp, Joseph C; TenHoor, Chris

    2015-01-01

    The therapeutic management of antibody-mediated autoimmune disease typically involves immunosuppressant and immunomodulatory strategies. However, perturbing the fundamental role of the neonatal Fc receptor (FcRn) in salvaging IgG from lysosomal degradation provides a novel approach - depleting the body of pathogenic immunoglobulin by preventing IgG binding to FcRn and thereby increasing the rate of IgG catabolism. Herein, we describe the discovery and preclinical evaluation of fully human monoclonal IgG antibody inhibitors of FcRn. Using phage display, we identified several potent inhibitors of human-FcRn in which binding to FcRn is pH-independent, with over 1000-fold higher affinity for human-FcRn than human IgG-Fc at pH 7.4. FcRn antagonism in vivo using a human-FcRn knock-in transgenic mouse model caused enhanced catabolism of exogenously administered human IgG. In non-human primates, we observed reductions in endogenous circulating IgG of >60% with no changes in albumin, IgM, or IgA. FcRn antagonism did not disrupt the ability of non-human primates to mount IgM/IgG primary and secondary immune responses. Interestingly, the therapeutic anti-FcRn antibodies had a short serum half-life but caused a prolonged reduction in IgG levels. This may be explained by the high affinity of the antibodies to FcRn at both acidic and neutral pH. These results provide important preclinical proof of concept data in support of FcRn antagonism as a novel approach to the treatment of antibody-mediated autoimmune diseases. PMID:25954273

  4. Knockdown of FcγRIII in an arthritic temporomandibular joint reduced the nociceptive response

    PubMed Central

    Kramer, Phillip R.; Puri, Jyoti; Bellinger, Larry L.

    2010-01-01

    FcγRIII (CD16) is a receptor expressed on immune cells that selectively binds immmunoglobulin G (IgG) molecules, IgG binding results in cellular activation and cytokine release. IgG is an important factor in arthritis and can be found in arthritic temporomandibular joints (TMJ). We hypothesize that a reduction in FcγRIII expression in the TMJ tissues will reduce the nociceptive and inflammatory response in an inflamed joint. To test this hypothesis siRNA, either naked or complexed with linear polyethylenimine (PEI) was injected into the superior joint space of the TMJ. After administration of siRNA the joint was injected with saline or with complete Freund’s adjuvant (CFA) to induce arthritis. Nociceptive responses were quantitated in the rat by measuring the animal’s meal duration. FcγRIII expression in the TMJ tissue was assayed by immunocytochemistry or western. Cleavage of FcγRIII transcript was then assayed by 5′ rapid amplification of cDNA ends method (5′ RACE). Interleukin-1β (IL-1β) and IgG content was measured in the TMJ tissue by ELISA. The results indicate that injection of FcγRIII siRNA reduced the amount of FcγRIII in the TMJ tissues and that the transcript was cleaved in a manner consistent with a RNA interference mechanism. Moreover, injection of FcγRIII siRNA reduced the nociceptive response of rats with an arthritic TMJ and reduced the amount of pro-inflammatory cytokine IL-1β. We conclude that FcγRIII contributes to the pain resulting from inflammatory arthritis of the TMJ and that siRNA has the potential to be an effective treatment for this disorder. PMID:20589683

  5. Leukocyte Trafficking to the Small Intestine and Colon.

    PubMed

    Habtezion, Aida; Nguyen, Linh P; Hadeiba, Husein; Butcher, Eugene C

    2016-02-01

    Leukocyte trafficking to the small and large intestines is tightly controlled to maintain intestinal immune homeostasis, mediate immune responses, and regulate inflammation. A wide array of chemoattractants, chemoattractant receptors, and adhesion molecules expressed by leukocytes, mucosal endothelium, epithelium, and stromal cells controls leukocyte recruitment and microenvironmental localization in intestine and in the gut-associated lymphoid tissues (GALTs). Naive lymphocytes traffic to the gut-draining mesenteric lymph nodes where they undergo antigen-induced activation and priming; these processes determine their memory/effector phenotypes and imprint them with the capacity to migrate via the lymph and blood to the intestines. Mechanisms of T-cell recruitment to GALT and of T cells and plasmablasts to the small intestine are well described. Recent advances include the discovery of an unexpected role for lectin CD22 as a B-cell homing receptor GALT, and identification of the orphan G-protein-coupled receptor 15 (GPR15) as a T-cell chemoattractant/trafficking receptor for the colon. GPR15 decorates distinct subsets of T cells in mice and humans, a difference in species that could affect translation of the results of mouse colitis models to humans. Clinical studies with antibodies to integrin α4β7 and its vascular ligand mucosal vascular addressin cell adhesion molecule 1 are proving the value of lymphocyte trafficking mechanisms as therapeutic targets for inflammatory bowel diseases. In contrast to lymphocytes, cells of the innate immune system express adhesion and chemoattractant receptors that allow them to migrate directly to effector tissue sites during inflammation. We review the mechanisms for innate and adaptive leukocyte localization to the intestinal tract and GALT, and discuss their relevance to human intestinal homeostasis and inflammation.

  6. Dimensions of religious involvement and leukocyte telomere length.

    PubMed

    Hill, Terrence D; Ellison, Christopher G; Burdette, Amy M; Taylor, John; Friedman, Katherine L

    2016-08-01

    Although numerous studies suggest that religious involvement is associated with a wide range of favorable health outcomes, it is unclear whether this general pattern extends to cellular aging. In this paper, we tested whether leukocyte telomere length varies according to several dimensions of religious involvement. We used cross-sectional data from the Nashville Stress and Health Study (2011-2014), a large probability sample of 1252 black and white adults aged 22 to 69 living in Davidson County, TN, USA. Leukocyte telomere length was measured using the monochrome multiplex quantitative polymerase chain reaction method with albumin as the single-copy reference sequence. Dimensions of religious involvement included religiosity, religious support, and religious coping. Our multivariate analyses showed that religiosity (an index of religious attendance, prayer frequency, and religious identity) was positively associated with leukocyte telomere length, even with adjustments for religious support, religious coping, age, gender, race, education, employment status, income, financial strain, stressful life events, marital status, family support, friend support, depressive symptoms, smoking, heavy drinking, and allostatic load. Unlike religiosity, religious support and religious coping were unrelated to leukocyte telomere length across models. Depressive symptoms, smoking, heavy drinking, and allostatic load failed to explain any of the association between religiosity and telomere length. To our knowledge, this is the first population-based study to link religious involvement and cellular aging. Although our data suggest that adults who frequently attend religious services, pray with regularity, and consider themselves to be religious tend to exhibit longer telomeres than those who attend and pray less frequently and do not consider themselves to be religious, additional research is needed to establish the mechanisms underlying this association.

  7. Leukocyte profile in growing dwarf and landrace kids.

    PubMed

    Mbassa, G K; Poulsen, J S

    1991-06-01

    Total and differential leukocyte count profiles were studied in 62 clinically healthy Danish landrace kids and 34 clinically healthy dwarf kids from birth to 12 months of age in seven Danish herds. The objective was to determine the reference values in the two breeds and the influence of age, sex and environment and whether there are any breed differences. Parametric (mean +/- 2 standard deviations) and the nonparametric (5th to 95th percentile interval) values for each leukocyte type were closely related. The medians were very close to the means. The number of leukocytes was low in neonates, 7.1 +/- 1.5 and 7.0 +/- 2.1 x 10(9)/l in dwarf and landrace kids respectively. Values increased with age to 18.7 +/- 2.1 and 13.4 +/- 3.1 x 10(9)/l in the two breeds respectively at 8-12 months of age. There were significant differences in leukocyte counts between the breeds at 1-2 and 8-12 months of age and at 2-4 months between herds within the breeds. The number of lymphocyte and neutrophil cells were 2.6 +/- 0.8 and 3.9 +/- 1.1 x 10(9)/l respectively in neonatal dwarf and 4.1 +/- 1.5 and 2.3 +/- 1.1 x 10(9)/l respectively in landrace kids. Very high numbers of these cells were observed in dwarf and landrace kids respectively within 8 months, 10.7 +/- 1.1 and 8.2 +/- 3.3 lymphocytes and 6.8 +/- 1.7 and 4.4 +/- 2.6 x 10(9)/l neutrophils for the two breeds. Significant differences between the ages (within the breeds), breeds (within similar ages) and herds (within breeds in kids of similar ages) were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Indium-111 leukocyte scintigraphy in Wegener's granulomatosis involving the spleen

    SciTech Connect

    Morayati, S.J.; Fink-Bennett, D.

    1986-12-01

    Indium-111-labeled leukocyte scintigraphy was performed on a 44-yr-old man to exclude an occult abscess. Four- and twenty-four-hour images of the abdomen revealed splenic photopenia except for a rim of activity medially. A subsequent computed tomography (CT) study demonstrated necrosis or hemorrhage of the spleen except for a medial rim. Exploratory laparotomy demonstrated necrotizing vasculitis with granuloma formation consistent with Wegener's granulomatosis and a rim of viable splenic tissue corresponding to the radionuclide and CT studies.

  9. Quantitative reconstruction of leukocyte subsets using DNA methylation

    PubMed Central

    2014-01-01

    Background Cell lineage-specific DNA methylation patterns distinguish normal human leukocyte subsets and can be used to detect and quantify these subsets in peripheral blood. We have developed an approach that uses DNA methylation to simultaneously quantify multiple leukocyte subsets, enabling investigation of immune modulations in virtually any blood sample including archived samples previously precluded from such analysis. Here we assess the performance characteristics and validity of this approach. Results Using Illumina Infinium HumanMethylation27 and VeraCode GoldenGate Methylation Assay microarrays, we measure DNA methylation in leukocyte subsets purified from human whole blood and identify cell lineage-specific DNA methylation signatures that distinguish human T cells, B cells, NK cells, monocytes, eosinophils, basophils and neutrophils. We employ a bioinformatics-based approach to quantify these cell types in complex mixtures, including whole blood, using DNA methylation at as few as 20 CpG loci. A reconstruction experiment confirms that the approach could accurately measure the composition of mixtures of human blood leukocyte subsets. Applying the DNA methylation-based approach to quantify the cellular components of human whole blood, we verify its accuracy by direct comparison to gold standard immune quantification methods that utilize physical, optical and proteomic characteristics of the cells. We also demonstrate that the approach is not affected by storage of blood samples, even under conditions prohibiting the use of gold standard methods. Conclusions Cell mixture distributions within peripheral blood can be assessed accurately and reliably using DNA methylation. Thus, precise immune cell differential estimates can be reconstructed using only DNA rather than whole cells. PMID:24598480

  10. Biomechanics of the endothelium substrate influences leukocyte transmigration

    NASA Astrophysics Data System (ADS)

    Stroka, Kimberly; Aranda-Espinoza, Helim

    2012-02-01

    The effects of shear flow and cytokines on leukocyte transmigration are well understood. However, the effects of substrate stiffness on transmigration remain unexplored. We have developed an in vitro model that allows us to study leukocyte transmigration as a function of varying physiological substrate stiffness. Interestingly, leukocyte transmigration increased with increasing substrate stiffness below the endothelium. intercellular adhesion molecule-1 expression, stiffness, cytoskeletal arrangement, morphology, and cell-substrate adhesion could not account for the dependence of transmigration on substrate stiffness. We also explored the role of cell contraction and observed that (1) neutrophil transmigration caused large hole formation in monolayers on stiff substrates. (2) Neutrophil transmigration on soft substrates was increased by decreasing cell-cell adhesion. (3) Inhibition of myosin light chain kinase normalized the effects of substrate stiffness by reducing cell contraction on stiff substrates. These results demonstrate that neutrophil transmigration is regulated by MLCK-mediated generation of gaps at cell borders through substrate stiffness-dependent endothelial cell contraction.

  11. Curcumin modulates leukocyte and platelet adhesion in murine sepsis

    PubMed Central

    Vachharajani, Vidula; Wang, Si-Wei; Mishra, Nilamadhab; El-Gazzar, Mohammad; Yoza, Barbara; McCall, Charles

    2010-01-01

    Objective Circulating cell-endothelial cell interaction in sepsis is a rate-determining factor in organ dysfunction, and interventions targeting this process have a potential therapeutic value. In this project, we examined whether curcumin, an active ingredient of turmeric and an anti-inflammatory agent, could disrupt interactions between circulating blood cells and endothelium and improve survival in a murine model of sepsis. Methods Mice were subjected to cecal ligation and puncture (CLP) to induce sepsis vs. sham surgery. We studied leukocyte and platelet adhesion in cerebral microcirculation using intravital fluorescent video microscopy technique, blood brain barrier dysfunction using Evans Blue leakage method, P-selectin expression using dual radiolabeling technique and survival in mice subjected to Sham, CLP and CLP with curcumin pre-treatment (CLP+Curcumin). Results Curcumin significantly attenuated leukocyte and platelet adhesion in cerebral microcirculation, Evans Blue leakage in the brain tissue and improved survival in mice with CLP. P-selectin expression in mice with CLP+Curcumin was significantly attenuated compared to CLP in various microcirculatory beds including brain. Reduction in platelet adhesion was predominantly via modulation of endothelium by curcumin. Conclusion Curcumin pre-treatment modulates leukocyte and platelet adhesion and blood brain barrier dysfunction in mice with CLP via P-selectin expression and improves survival in mice with CLP. PMID:20690979

  12. Common leukocyte antigen staining of a primitive sarcoma.

    PubMed

    McDonnell, J M; Beschorner, W E; Kuhajda, F P; deMent, S H

    1987-04-15

    A 4-year-old boy presented with symptoms of tracheal obstruction and was found to have a polypoid tracheal mass, which was studied by biopsy. Light microscopy showed a tumor composed of small cells with round to oval dark nuclei, clumped chromatin, one to two nucleoli, and small, variable amounts of indistinct pink cytoplasm. In other areas the tumor had a loose, spindle appearance, with some cells showing more elongated nuclei, and fibrillar pink cytoplasm consistent with strap cells. Cross striations were not found. Electron microscopy showed desmosomes and 7 to 10 nm cytoplasmic filaments forming dense bodies. The findings are most consistent with a primitive sarcoma, probably rhabdomyosarcoma. Immunoperoxidase with three monoclonal antibodies for common leukocyte antigen showed diffuse membraneous staining with fresh-frozen tissue. All other lymphocyte and monocyte marker studies were negative. We believe that this case of anticommon leukocyte antigen staining, a rhabdomyosarcoma, represents the first report of a false positive reaction with monoclonal antibody to common leukocyte antigen.

  13. Impaired leukocyte phagocytosis in patients undergoing hemihepatectomy for liver metastases.

    PubMed

    Wiezer, M J; Meijer, C; Wallast-Groenewoud, H P; Tool, A T; Prins, H A; Houdijk, A P; Beelen, R H; Meijer, S; Hack, C E; van Leeuwen, P A

    1999-05-01

    Patients undergoing partial hepatectomy have an increased susceptibility to infection. To investigate whether this increased risk is related to impaired leukocyte function, we studied polymorphonuclear leukocyte (PMN) phagocytosis in patients undergoing a hemihepatectomy because of liver metastasis (LM, n = 11) and in patients undergoing major abdominal surgery because of abdominal malignancy (AM, n = 8). Eight healthy volunteers (HVs) served as controls. Leukocyte suspensions were incubated with fluorescein isothiocyanate-labeled Staphylococcus aureus, and phagocytosis was measured by flow cytometry. Preoperative PMN phagocytosis, in the presence of autologous plasma, was significantly less in patients with LM compared with patients with AM or HVs. This impaired phagocytosis was potentially restored in the presence of normal plasma. The decreased phagocytic capacity of PMNs from patients with LM was not related to levels of known plasma opsonins or phenotypic changes of PMNs. Rather, it was related to a deficiency of unidentified plasma factors. After surgery, the phagocytic capacity of PMNs of patients with AM decreased by approximately 30%, which correlated with decreasing levels of immunoglobulin G and C3. In conclusion, patients with LM had a decreased PMN phagocytic capacity before surgery. This impairment in phagocytosis disappeared 1 week after surgery. We propose that the presence of LM leads to a deficiency of factor(s) in the blood that impairs PMN phagocytic capacity.

  14. Exposure to mercury alters early activation events in fish leukocytes.

    PubMed Central

    MacDougal, K C; Johnson, M D; Burnett, K G

    1996-01-01

    Although fish in natural populations may carry high body burdens of both organic and inorganic mercury, the effects of this divalent metal on such lower vertebrates is poorly understood. In this report, inorganic mercury in the form of mercuric chloride (HgCl2) is shown to produce both high-dose inhibition and low-dose activation of leukocytes in a marine teleost fish, Sciaenops ocellatus. Concentrations of inorganic mercury > or = 10 microM suppressed DNA synthesis and induced rapid influx of radiolabeled calcium, as well as tyrosine phosphorylation of numerous cellular proteins. Lower concentrations (0.1-1 microM) of HgCl2 that activated cell growth also induced a slow sustained rise in intracellular calcium in cells loaded with the calcium indicator dye fura-2, but did not produce detectable tyrosine phosphorylation of leukocyte proteins. These studies support the possibility that subtoxic doses of HgCl2 may inappropriately activate teleost leukocytes, potentially altering the processes that regulate the magnitude and specificity of the fish immune response to environmental pathogens. Images Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. PMID:8930553

  15. Report: Nuclei segmentation of leukocytes in blood smear digital images.

    PubMed

    Abbas, Naveed; Mohamad, Dzulkifli; Abdullah, Abdul Hanan; Saba, Tanzila; Al-Rodhaan, Mznah; Al-Dhelaan, Abdullah

    2015-09-01

    The Leukocytes are differentiated from each other on the basis of their nuclei, demanded in many Medical studies, especially in all types of Leukemia by the Hematologists to note the disorder caused by specific type of Leukocyte. Leukemia is a life threatening disease. The work for diagnosing is manually carried out by the Hematologists involving much labor, time and human errors. The problems mentioned are easily addressed through computer vision techniques, but still accuracy and efficiency are demanded in terms of the basic and challenging step segmentation of Leukocyte's nuclei. The underlying study proposed better method in terms of accuracy and efficiency by designing a dynamic convolution filter for boosting low intensity values in the separated green channel of an RGB image and suppressing the high values in the same channel. The high values in the green channel become 255 (background) while the nuclei always have low values in the green channel and thus clearly appear as foreground. The proposed technique is tested on 365 images achieving an overall accuracy of 95.89%, while improving the efficiency by 10%. The proposed technique achieved its targets in a realistic way by improving the accuracy as well as the efficiency and both are highly required in the area.

  16. Carbohydrate ligands for endothelial - Leukocyte adhesion molecule 1

    SciTech Connect

    Tiemeyer, M.; Swiedler, S.J.; Ishihara, Masayuki; Moreland, M.; Schweingruber, H.; Hirtzer, P.; Brandley, B.K. )

    1991-02-15

    The acute inflammatory response requires that circulating leukocytes bind to and penetrate the vascular wall to access the site of injury. Several receptors have been implicated in this interaction, including a family of putative carbohydrate-binding proteins. The authors report here the identification of an endogenous carbohydrate ligand for one of these receptors, endothelial-leukocyte adhesion molecule 1 (ELAM-1). Radiolabeled COS cells transfected with a plasmid containing the cDNA for ELAM-1 were used as probes to screen glycolipids extracted from human leukocytes. COS cells transfected with this plasmid adhered to a subset of sialylated glycolipids resolved on TLC plates or adsorbed on polyvinyl chloride microtiter wells. Adhesion to these glycolipids required calcium but was not inhibited by heparin, chondroitin sulfate, keratan sulfate, or yeast phosphomannan. Monosaccharide composition, linkage analysis, and fast atom bombardment mass spectrometry of the glycolipids indicate that the ligands for ELAM-1 are terminally sialylated lactosylceramides with a variable number of N-acetyllactosamine repeats and at least one fucosylated N-acetylglucosamine residue.

  17. Imaging leukocytes in vivo with third harmonic generation microscopy

    NASA Astrophysics Data System (ADS)

    Tsai, Cheng-Kun; Chen, Chien-Kuo; Chen, Yu-Shing; Wu, Pei-Chun; Hsieh, Tsung-Yuan; Liu, Han-Wen; Yeh, Chiou-Yueh; Lin, Win-Li; Chia, Jean-San; Liu, Tzu-Ming

    2013-02-01

    Without a labeling, we demonstrated that lipid granules in leukocytes have distinctive third harmonic generation (THG) contrast. Excited by a 1230nm femtosecond laser, THG signals were generated at a significantly higher level in neutrophils than other mononuclear cells, whereas signals in agranular lymphocytes were one order smaller. These characteristic THG features can also be observed in vivo to trace the newly recruited leukocytes following lipopolysaccharide (LPS) challenge. Furthermore, using video-rate THG microscopy, we also captured images of blood cells in human capillaries. Quite different from red-blood-cells, every now and then, round and granule rich blood cells with strong THG contrast appeared in circulation. The corresponding volume densities in blood, evaluated from their frequencies of appearance and the velocity of circulation, fall within the physiological range of human white blood cell counts. These results suggested that labeling-free THG imaging may provide timely tracing of leukocyte movement and hematology inspection without disturbing the normal cellular or physiological status.

  18. Cytochalasin B: Effect on Lysosomal Enzyme Release from Human Leukocytes

    PubMed Central

    Zurier, Robert B.; Hoffstein, Sylvia; Weissmann, Gerald

    1973-01-01

    The morphological and biochemical consequences of treatment of human peripheral blood leukocytes with cytochalasin B were studied. Incubation of human polymorphs with cytochalasin B resulted in nuclear and cytoplasmic spreading, but not in spontaneous release of lysosomal enzymes. Cytochalasin B inhibited particle uptake. Consequently, phagocytic vacuoles were not observed; instead, granule contents were discharged directly into the surrounding medium when cytochalasin B-treated cells were challenged with zymosan particles. Cytochalasin B enhanced the release of lysosomal enzymes from human polymorphonuclear leukocytes whether these encountered zymosan particles or immune complexes on a nonphagocytosable Millipore filter. Cytochalasin B-treated leukocytes thus constitute a model system for quantitative study of lysosome fusion. Augmented enzyme release was blocked by prior treatment of cells with pharmacological doses of agents that influence the accumulation of cyclic nucleotides (cyclic nucleotides themselves, prostaglandin E1) or by compounds that interfere with microtubule function (e.g., colchicine, vinblastine). These observations suggest that one action of cytochalasin B on phagocytic cells is to remove the normal constraints to merger of granules, either with each other or with the plasma membrane, and that intact microtubule function is required for translocation of lysosomes. Images PMID:4351807

  19. Leukocyte trafficking: Can we bring the fight to the tumor?

    PubMed

    Pachynski, Russell; Nazha, Jonathon; Kohrt, Holbrook

    2016-03-01

    Control of leukocyte trafficking plays a critical role in the establishment of effective immune responses. It is now well established that the number or ratio of effector to suppressor immune cells within the tumor microenvironment can significantly impact tumor growth and clinical outcomes. Recently approved immunotherapies by the FDA, and those in development, aim to stimulate effector immune cell function. For example, many checkpoint inhibitors seek to stimulate an immune response to tumors by reversing T-cell exhaustion. However, activation of the immune response outside the tumor microenvironment can lead to sometimes fatal immune-mediated adverse events -- the result of "on-target, off-tumor" effects. Thus, control of localization of these activated effector cells remains a critical component of optimizing tumor response while minimizing immune-mediated adverse events. Chemokines and chemoattractants, along with their receptors on immune cells, govern leukocyte trafficking; thus, understanding their expression pattern in the context of the tumor microenvironment and developing approaches to favorably alter those should lead to improved efficacy of current immunotherapeutics. This review highlights the background of cancer immunotherapy, leukocyte trafficking, and some novel approaches being utilized to optimize recruitment of effector immune cells into the tumor microenvironment. Future combinatorial immunotherapy should incorporate therapeutics aimed at 1) favorably altering the tumor microenvironment, 2) activating effector immune cells, and 3) optimizing effector cell trafficking into tumors.

  20. Neonatal Fc receptor expression in dendritic cells mediates protective immunity against colorectal cancer.

    PubMed

    Baker, Kristi; Rath, Timo; Flak, Magdalena B; Arthur, Janelle C; Chen, Zhangguo; Glickman, Jonathan N; Zlobec, Inti; Karamitopoulou, Eva; Stachler, Matthew D; Odze, Robert D; Lencer, Wayne I; Jobin, Christian; Blumberg, Richard S

    2013-12-12

    Cancers arising in mucosal tissues account for a disproportionately large fraction of malignancies. Immunoglobulin G (IgG) and the neonatal Fc receptor for IgG (FcRn) have an important function in the mucosal immune system that we have now shown extends to the induction of CD8(+) T cell-mediated antitumor immunity. We demonstrate that FcRn within dendritic cells (DCs) was critical for homeostatic activation of mucosal CD8(+) T cells that drove protection against the development of colorectal cancers and lung metastases. FcRn-mediated tumor protection was driven by DCs activation of endogenous tumor-reactive CD8(+) T cells via the cross-presentation of IgG complexed antigens (IgG IC), as well as the induction of cytotoxicity-promoting cytokine secretion, particularly interleukin-12, both of which were independently triggered by the FcRn-IgG IC interaction in murine and human DCs. FcRn thus has a primary role within mucosal tissues in activating local immune responses that are critical for priming efficient anti-tumor immunosurveillance.

  1. FC-NIRS: A Functional Connectivity Analysis Tool for Near-Infrared Spectroscopy Data.

    PubMed

    Xu, Jingping; Liu, Xiangyu; Zhang, Jinrui; Li, Zhen; Wang, Xindi; Fang, Fang; Niu, Haijing

    2015-01-01

    Functional near-infrared spectroscopy (fNIRS), a promising noninvasive imaging technique, has recently become an increasingly popular tool in resting-state brain functional connectivity (FC) studies. However, the corresponding software packages for FC analysis are still lacking. To facilitate fNIRS-based human functional connectome studies, we developed a MATLAB software package called "functional connectivity analysis tool for near-infrared spectroscopy data" (FC-NIRS). This package includes the main functions of fNIRS data preprocessing, quality control, FC calculation, and network analysis. Because this software has a friendly graphical user interface (GUI), FC-NIRS allows researchers to perform data analysis in an easy, flexible, and quick way. Furthermore, FC-NIRS can accomplish batch processing during data processing and analysis, thereby greatly reducing the time cost of addressing a large number of datasets. Extensive experimental results using real human brain imaging confirm the viability of the toolbox. This novel toolbox is expected to substantially facilitate fNIRS-data-based human functional connectome studies. PMID:26539473

  2. Analysis of Fcγ Receptor IIIa and IIa Polymorphisms: Lack of Correlation with Outcome in Trastuzumab-Treated Breast Cancer Patients

    PubMed Central

    Hurvitz, Sara A.; Betting, David J.; Stern, Howard M.; Quinaux, Emmanuel; Stinson, Jeremy; Seshagiri, Somasekar; Zhao, Ying; Buyse, Marc; Mackey, John; Driga, Adrian; Damaraju, Sambasivarao; Sliwkowski, Mark X.; Robert, Nicholas J.; Valero, Vicente; Crown, John; Falkson, Carla; Brufsky, Adam; Pienkowski, Tadeusz; Eiermann, Wolfgang; Martin, Miguel; Bee, Valerie; Marathe, Omkar; Slamon, Dennis J.; Timmerman, John M.

    2013-01-01

    Purpose The mechanisms by which trastuzumab imparts clinical benefit remain incompletely understood. Antibody-dependent cellular cytotoxicity via interactions with Fcγ receptors (FcγR) on leukocytes may contribute to its anti-tumor effects. Single nucleotide polymorphisms (SNPs) in FCGR3A and FCGR2A genes lead to amino acid substitutions at positions 158 and 131 respectively and affect binding of antibodies to FcγR such that 158V/V and 131H/H bind with highest affinity. This study aimed to determine whether high affinity SNPs are associated with disease free survival (DFS) among patients with HER2-positive non-metastatic breast cancer. Experimental Design Genomic DNA was isolated from 1,286 patients enrolled in a trial of adjuvant trastuzumab-based chemotherapy. Genotyping was performed using Sanger sequencing and Sequenom mass spectrometry. Results 1,189 patient samples were successfully genotyped for FCGR3A and 1,218 for FCGR2A. Compared to the overall results of the BCIRG006 study, in the subset of patients genotyped in this analysis, a less robust improvement in DFS was observed for the trastuzumab arms compared to control arm (HR=0.842, P=0.1925). When stratified for prognostic features, the HR in favor of trastuzumab was consistent with that of the overall study (HR=0.74, P=0.036). No correlation between DFS and FCGR3A/2A genotypes was seen for trastuzumab-treated patients (158V/V vs V/F vs F/F, P=0.98; 131H/H vs H/R vs R/R, P=0.76; 158V/V and/or 131H/H vs others, P=0.67). Conclusion This analysis evaluating the association between FCGR3A/2A genotypes and trastuzumab efficacy in HER2-positive breast cancer did not demonstrate a correlation between FCGR3A-V/F and FCGR2A-H/R SNPs and DFS in patients treated with trastuzumab. PMID:22504044

  3. The Transcription Factor Ehf Is Involved in TGF-β-Induced Suppression of FcεRI and c-Kit Expression and FcεRI-Mediated Activation in Mast Cells.

    PubMed

    Yamazaki, Susumu; Nakano, Nobuhiro; Honjo, Asuka; Hara, Mutsuko; Maeda, Keiko; Nishiyama, Chiharu; Kitaura, Jiro; Ohtsuka, Yoshikazu; Okumura, Ko; Ogawa, Hideoki; Shimizu, Toshiaki

    2015-10-01

    FcεRI, which is composed of α, β, and γ subunits, plays an important role in IgE-mediated allergic responses. TGF-β1 has been reported to suppress FcεRI and stem cell factor receptor c-Kit expression on mast cell surfaces and to suppress mast cell activation induced by cross-linking of FcεRI. However, the molecular mechanism by which these expressions and activation are suppressed by TGF-β1 remains unclear. In this study, we found that the expression of Ets homologous factor (Ehf), a member of the Ets family transcriptional factors, is upregulated by TGF-β/Smad signaling in mouse bone marrow-derived mast cells (BMMCs). Forced expression of Ehf in BMMCs repressed the transcription of genes encoding FcεRIα, FcεRIβ, and c-Kit, resulting in a reduction in cell surface FcεRI and c-Kit expression. Additionally, forced expression of Ehf suppressed FcεRI-mediated degranulation and cytokine production. Ehf inhibited the promoter activity of genes encoding FcεRIα, FcεRIβ, and c-Kit by binding to these gene promoters. Furthermore, the mRNA levels of Gata1, Gata2, and Stat5b were lower in BMMCs stably expressing Ehf compared with control cells. Because GATA-1 and GATA-2 are positive regulators of FcεRI and c-Kit expression, decreased expression of GATAs may be also involved in the reduction of FcεRI and c-Kit expression. Decreased expression of Stat5 may contribute to the suppression of cytokine production by BMMCs. In part, mast cell response to TGF-β1 was mimicked by forced expression of Ehf, suggesting that TGF-β1 suppresses FcεRI and c-Kit expression and suppresses FcεRI-mediated activation through upregulation of Ehf.

  4. Peripheral blood leukocyte count as an index of defense status in the leukopenic host

    SciTech Connect

    Cawley, S.; Findon, G.; Miller, T.E.

    1988-07-01

    These experimental studies have investigated the reliability of the peripheral blood leukocyte count to predict whether the leukopenic host can contain or eliminate infection. Additionally, we have investigated the possibility that determination of leukocyte recruitment, supplementary to peripheral blood leukocyte counts, might allow individuals with neutropenia at risk from serious infection to be distinguished with greater certainty. Varying doses of radiation, cyclophosphamide, and methylprednisolone were used to induce distinct levels of leukopenia in rats. Leukocyte recruitment was measured by quantifying the response of neutropenic animals to evocative, subcutaneous stimuli, and the results of this assay were then compared with circulating leukocyte counts in the same individuals. Six models of experimentally induced infection were used to compare circulating and recruitable leukocytes as indicators of the susceptibility of the leukopenic host to infection. Response curves relating leukocyte numbers to host resistance were similar when circulating or recruitable leukocytes were used as an index of defense capability. These findings support the use of peripheral blood leukocyte numbers as an index of resistance to infection in individuals with leukopenia and suggest that functional analyses such as leukocyte recruitment are unlikely to provide additional information.

  5. Dose and dose rate effects of whole-body proton irradiation on leukocyte populations and lymphoid organs: part I

    NASA Technical Reports Server (NTRS)

    Gridley, Daila S.; Pecaut, Michael J.; Dutta-Roy, Radha; Nelson, Gregory A.

    2002-01-01

    The goal of part I of this study was to evaluate the effects of whole-body proton irradiation on lymphoid organs and specific leukocyte populations. C57BL/6 mice were exposed to the entry region of the proton Bragg curve to total doses of 0.5 gray (Gy), 1.5 Gy, and 3.0 Gy, each delivered at a low dose rate (LDR) of 1 cGy/min and high dose rate (HDR) of 80 cGy/min. Non-irradiated and 3 Gy HDR gamma-irradiated groups were included as controls. At 4 days post-irradiation, highly significant radiation dose-dependent reductions were observed in the mass of both lymphoid organs and the numbers of leukocytes and T (CD3(+)), T helper (CD3(+)/CD4(+)), T cytotoxic (CD3(+)/CD8(+)), and B (CD19(+)) cells in both blood and spleen. A less pronounced dose effect was noted for natural killer (NK1.1(+) NK) cells in spleen. Monocyte, but not granulocyte, counts in blood were highly dose-dependent. The numbers for each population generally tended to be lower with HDR than with LDR radiation; a significant dose rate effect was found in the percentages of T and B cells, monocytes, and granulocytes and in CD4(+):CD8(+) ratios. These data indicate that mononuclear cell response to the entry region of the proton Bragg curve is highly dependent upon the total dose and that dose rate effects are evident with some cell types. Results from gamma- and proton-irradiated groups (both at 3 Gy HDR) were similar, although proton-irradiation gave consistently lower values in some measurements.

  6. Bovine leukocyte adhesion deficiency--clinical course and laboratory findings in eight affected animals.

    PubMed

    Müller, K E; Bernadina, W E; Kalsbeek, H C; Hoek, A; Rutten, V P; Wentink, G H

    1994-03-01

    The clinical course of Bovine Leukocyte Adhesion Deficiency (BLAD) in eight Holstein Friesian cattle is described. Affected animals were presented with a history of poor thriving and recurrent bacterial infections. Five of these animals had to be killed because of severe respiratory disease shortly after admittance. Three affected animals survived calfhood only as a result of frequent antibacterial treatments. At one year of age, failure to thrive and stunted growth were still evident, but infections requiring antibiotic treatments occurred only sporadically. Clinical manifestations of BLAD were found in the digestive system (gingivitis, periodontitis, alveolar periostitis, diarrhoea), the respiratory system and the skin (impaired wound healing, chronic dermatitis). A leukocytosis based on a mature neutrophilia, which persisted during infection-free periods, was observed in all animals. Granulocytes were substantially deficient of beta 2-integrin expression on their membranes. Anaemia, which was noted in four animals, may be related to the Anaemia of Inflammatory Disease Complex (AID). The serum total protein content increased with time and was associated with elevated gamma-globulin levels. We suggest that, at a certain age, animals affected with BLAD are able to cope with environmental agents due to compensatory mechanisms of the immune system. PMID:8009815

  7. Bovine leukocyte adhesion deficiency--clinical course and laboratory findings in eight affected animals.

    PubMed

    Müller, K E; Bernadina, W E; Kalsbeek, H C; Hoek, A; Rutten, V P; Wentink, G H

    1994-07-01

    The clinical course of Bovine Leukocyte Adhesion Deficiency (BLAD) in eight Holstein Friesian cattle is described. Affected animals were presented with a history of poor thriving and recurrent bacterial infections. Five of these animals had to be killed because of severe respiratory disease shortly after admittance. Three affected animals survived calfhood only as a result of frequent antibacterial treatments. At one year of age, failure to thrive and stunted growth were still evident, but infections requiring antibiotic treatments occurred only sporadically. Clinical manifestations of BLAD were found in the digestive system (gingivitis, periodontitis, alveolar periostitis, diarrhoea), the respiratory system and the skin (impaired wound healing, chronic dermatitis). A leukocytosis based on a mature neutrophilia, which persisted during infection-free periods, was observed in all animals. Granulocytes were substantially deficient of beta 2-integrin expression on their membranes. Anaemia, which was noted in four animals, may be related to the Anaemia of Inflammatory Disease Complex (AID). The serum total protein content increased with time and was associated with elevated gamma-globulin levels. We suggest that, at a certain age, animals affected with BLAD are able to cope with environmental agents due to compensatory mechanisms of the immune system. PMID:7985357

  8. Extending half-life by indirect targeting of the neonatal Fc receptor (FcRn) using a minimal albumin binding domain.

    PubMed

    Andersen, Jan Terje; Pehrson, Rikard; Tolmachev, Vladimir; Daba, Muluneh Bekele; Abrahmsén, Lars; Ekblad, Caroline

    2011-02-18

    The therapeutic and diagnostic efficiency of engineered small proteins, peptides, and chemical drug candidates is hampered by short in vivo serum half-life. Thus, strategies to tailor their biodistribution and serum persistence are highly needed. An attractive approach is to take advantage of the exceptionally long circulation half-life of serum albumin or IgG, which is attributed to a pH-dependent interaction with the neonatal Fc receptor (FcRn) rescuing these proteins from intracellular degradation. Here, we present molecular evidence that a minimal albumin binding domain (ABD) derived from streptococcal protein G can be used for efficient half-life extension by indirect targeting of FcRn. We show that ABD, and ABD recombinantly fused to an Affibody molecule, in complex with albumin does not interfere with the strictly pH-dependent FcRn-albumin binding kinetics. The same result was obtained in the presence of IgG. An in vivo study performed in rat confirmed that the clinically relevant human epidermal growth factor 2 (HER2)-targeting Affibody molecule fused to ABD has a similar half-life and biodistribution profile as serum albumin. The proof-of-concept described may be broadly applicable to extend the in vivo half-life of short lived biological or chemical drugs ultimately resulting in enhanced therapeutic or diagnostic efficiency, a more favorable dosing regimen, and improved patient compliance.

  9. Gamma ray generator

    SciTech Connect

    Firestone, Richard B; Reijonen, Jani

    2014-05-27

    An embodiment of a gamma ray generator includes a neutron generator and a moderator. The moderator is coupled to the neutron generator. The moderator includes a neutron capture material. In operation, the neutron generator produces neutrons and the neutron capture material captures at least some of the neutrons to produces gamma rays. An application of the gamma ray generator is as a source of gamma rays for calibration of gamma ray detectors.

  10. Analysis of leukocyte populations in Canadian Holsteins classified as high or low immune responders for antibody- or cell-mediated immune response

    PubMed Central

    Hine, Brad C.; Cartwright, Shannon L.; Mallard, Bonnie A.

    2012-01-01

    Selection of dairy cattle for increased milk production with little or no emphasis on health traits leads to an increased prevalence of disease. A possible genetic solution to this problem is to combine production and immune response traits in a weighted selection index. In the current study, leukocyte populations in heifers identified as having a high antibody-mediated immune response (HiAMIR) or high cell-mediated immune response (HiCMIR) phenotype were compared before and after immunization in order to identify leukocyte population profiles associated with these phenotypes. The results demonstrated that the HiCMIR-phenotype animals had a higher baseline proportion of gamma-delta T-cells in peripheral blood. Also, the observed increase in the proportion of B-cells in peripheral blood in response to immunization was greater in the HiAMIR-phenotype animals. It is expected that identifying leukocyte population profiles associated with immune response phenotypes will improve our ability to identify animals with enhanced overall immune responsiveness. PMID:23024458

  11. Basis of the 1:1 stoichiometry of the high affinity receptor Fc epsilon RI-IgE complex.

    PubMed

    Keown, M B; Ghirlando, R; Mackay, G A; Sutton, B J; Gould, H J

    1997-01-01

    A soluble fragment of the high-affinity IgE receptor Fc epsilon RI alpha-chain (sFc epsilon RI alpha) binds to the Fc fragment of IgE (IgE-Fc) as a 1:1 complex. IgE-Fc consists of a dimer of the C epsilon 2, C epsilon 3 and C epsilon 4 domains of the epsilon-heavy chain of IgE. This region of IgE has been modelled on the crystal structure of the Fc region of IgG1, which exhibits twofold rotational symmetry. This implies that IgE should be divalent with respect to its ligands. X-ray scattering studies reveal however that the twofold rotational symmetry of IgE-Fc is perturbed by a bend in the linker region between the C epsilon 2 and C epsilon 3 domains. The 1:1 stoichiometry could then arise from the conformational asymmetry or from steric occlusion of one of the sites by the overhanging C epsilon 2 domains. To test this hypothesis we have expressed a recombinant epsilon-chain fragment containing C epsilon 3 and C epsilon 4. This product, Fc epsilon 3-4, is secreted from cells as a disulphide linked dimer and binds with higher affinity than either IgE or IgE-Fc to cell surface Fc epsilon RI. Titration experiments, together with molecular mass measurements of the Fc epsilon 3-4/sFc epsilon RI alpha complex, reveal that Fc epsilon 3-4 binds only a single receptor molecule. This excludes the possibility that steric hindrance by C epsilon 2 accounts for the unexpected stoichiometry.

  12. Neonatal Fc Receptor Regulation of Lung Immunoglobulin and CD103+ Dendritic Cells Confers Transient Susceptibility to Tuberculosis

    PubMed Central

    Lozza, Laura; Reece, Stephen T.; Perdomo, Carolina; Zedler, Ulrike; Hahnke, Karin; Oberbeck-Mueller, Dagmar; Dorhoi, Anca

    2016-01-01

    The neonatal Fc receptor (FcRn) extends the systemic half-life of IgG antibodies by chaperoning bound Fc away from lysosomal degradation inside stromal and hematopoietic cells. FcRn also transports IgG across mucosal barriers into the lumen, and yet little is known about how FcRn modulates immunity in the lung during homeostasis or infection. We infected wild-type (WT) and FcRn-deficient (fcgrt−/−) mice with Pseudomonas aeruginosa or Mycobacterium tuberculosis to investigate whether recycling and transport of IgG via FcRn influences innate and adaptive immunity in the lung in response to bacterial infection. We found that FcRn expression maintains homeostatic IgG levels in lung and leads to preferential secretion of low-affinity IgG ligands into the lumen. Fcgrt−/− animals exhibited no evidence of developmental impairment of innate immunity in the lung and were able to efficiently recruit neutrophils in a model of acute bacterial pneumonia. Although local humoral immunity in lung increased independently of the presence of FcRn during tuberculosis, there was nonetheless a strong impact of FcRn deficiency on local adaptive immunity. We show that the quantity and quality of IgG in airways, as well as the abundance of dendritic cells in the lung, are maintained by FcRn. FcRn ablation transiently enhanced local T cell immunity and neutrophil recruitment during tuberculosis, leading to a lower bacterial burden in lung. This novel understanding of tissue-specific modulation of mucosal IgG isotypes in the lung by FcRn sheds light on the role of mucosal IgG in immune responses in the lung during homeostasis and bacterial disease. PMID:27481246

  13. Multiple Plasmodium falciparum Erythrocyte Membrane Protein 1 Variants per Genome Can Bind IgM via Its Fc Fragment Fcμ.

    PubMed

    Jeppesen, Anine; Ditlev, Sisse Bolm; Soroka, Vladyslav; Stevenson, Liz; Turner, Louise; Dzikowski, Ron; Hviid, Lars; Barfod, Lea

    2015-10-01

    The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) adhesive proteins expressed on the surfaces of infected erythrocytes (IEs) are of key importance in the pathogenesis of P. falciparum malaria. Several structurally and functionally defined PfEMP1 types have been associated with severe clinical manifestations, such as cerebral malaria in children and placental malaria in pregnant women. PfEMP1 that can bind the Fc part of IgM (Fcμ) characterizes one such type, although the functional significance of this IgM binding to PfEMP1 remains unclear. In this study, we report the identification and functional analysis of five IgM-binding PfEMP1 proteins encoded by P. falciparum NF54. In addition to the VAR2CSA-type PFL0030c protein, already known to bind Fcμ and to mediate chondroitin sulfate A (CSA)-specific adhesion of IEs in the placenta, we found four PfEMP1 proteins not previously known to bind IgM this way. Although they all contained Duffy binding-like ε (DBLε) domains similar to those in VAR2CSA-type PfEMP1, they did not mediate IE adhesion to CSA, and IgM binding did not shield IEs from phagocytosis of IgG-opsonized IEs. In this way, these new IgM-binding PfEMP1 proteins resemble the rosette-mediating and IgM-binding PfEMP1 HB3VAR06, but none of them mediated formation of rosettes. We could map the capacity for Fc-specific IgM binding to DBLε domains near the C terminus for three of the four PfEMP1 proteins tested. Our study provides new evidence regarding Fc-dependent binding of IgM to PfEMP1, which appears to be a common and multifunctional phenotype.

  14. Fcγ and Complement Receptors and Complement Proteins in Neutrophil Activation in Rheumatoid Arthritis: Contribution to Pathogenesis and Progression and Modulation by Natural Products

    PubMed Central

    Paoliello-Paschoalato, Adriana Balbina; Marchi, Larissa Fávaro; de Andrade, Micássio Fernandes; Kabeya, Luciana Mariko; Donadi, Eduardo Antônio; Lucisano-Valim, Yara Maria

    2015-01-01

    Rheumatoid arthritis (RA) is a highly disabling disease that affects all structures of the joint and significantly impacts on morbidity and mortality in RA patients. RA is characterized by persistent inflammation of the synovial membrane lining the joint associated with infiltration of immune cells. Eighty to 90% of the leukocytes infiltrating the synovia are neutrophils. The specific role that neutrophils play in the onset of RA is not clear, but recent studies have evidenced that they have an important participation in joint damage and disease progression through the release of proteolytic enzymes, reactive oxygen species (ROS), cytokines, and neutrophil extracellular traps, in particular during frustrated phagocytosis of immune complexes (ICs). In addition, the local and systemic activation of the complement system contributes to the pathogenesis of RA and other IC-mediated diseases. This review discusses (i) the participation of Fcγ and complement receptors in mediating the effector functions of neutrophils in RA; (ii) the contribution of the complement system and ROS-dependent and ROS-independent mechanisms to joint damage in RA; and (iii) the use of plant extracts, dietary compounds, and isolated natural compounds in the treatment of RA, focusing on modulation of the effector functions of neutrophils and the complement system activity and/or activation. PMID:26346244

  15. Construction and immunogenicity of a new Fc-based subunit vaccine candidate against Mycobacterium tuberculosis.

    PubMed

    Kebriaei, Abdollah; Derakhshan, Mohammad; Meshkat, Zahra; Eidgahi, Mohammad Reza Akbari; Rezaee, Seyed Abdolrahim; Farsiani, Hadi; Mosavat, Arman; Soleimanpour, Saman; Ghazvini, Kiarash

    2016-09-01

    As an ancient disease, tuberculosis (TB) is a major global health threat. Therefore, there is an urgent need for an effective and safe anti-TB vaccine. In the current study, a delivery system of Fc domain of mouse IgG2a and early secreted antigenic target protein 6 (ESAT-6) was evaluated for the selective uptake of antigens by antigen-presenting cells (APCs). Thus, it was based on the immunogenicity of a fusion protein. The study was initiated by the transfer of recombinant expression vectors of pPICZαA-ESAT-6:Fcγ2a and pPICZαA-ESAT-6: His into Pichia pastoris (P. pastoris). Recombinant proteins were assessed for immunogenicity following the immunoblotting analysis. High levels of IFN-γ and IL-12 were produced to induce Th1-type cellular responses through vaccination with both recombinant proteins [ESAT-6:Fcγ2a (EF) and ESAT-6:His (EH)]. The Fc-tagged recombinant protein induced more effective Th1-type cellular responses with a low increment in IL-4 compared to PBS, BCG, and EH groups. Although in all the immunized groups, the ratio of IFN-γ/IL-4 was in favor of Th1 responses, the highest Th1/Th2 balance was observed in EF immunized group. Fc fragment of mouse IgG2a may induce a selective uptake of APCs towards the cross-presentation and formation of Th1 responses in favor of an appropriate protective anti-tuberculosis reaction. Thus, further research on Fc-fusion proteins is required to develop Fc-based TB vaccines. PMID:27251218

  16. Syndecan-Fc Hybrid Molecule as a Potent In Vitro Microbicidal Anti-HIV-1 Agent▿

    PubMed Central

    Bobardt, Michael D.; Chatterji, Udayan; Schaffer, Lana; de Witte, Lot; Gallay, Philippe A.

    2010-01-01

    In the absence of a vaccine, there is an urgent need for the development of safe and effective topical microbicides to prevent the sexual transmission of human immunodeficiency virus type 1 (HIV-1). In this study, we proposed to develop a novel class of microbicides using syndecan as the antiviral agent. Specifically, we generated a soluble syndecan-Fc hybrid molecule by fusing the ectodomain of syndecan-1 to the Fc domain of a human IgG. We then tested the syndecan-Fc hybrid molecule for various in vitro microbicidal anti-HIV-1 properties. Remarkably, the syndecan-Fc hybrid molecule possesses multiple attractive microbicidal properties: (i) it blocks HIV-1 infection of primary targets including T cells, macrophages, and dendritic cells (DC); (ii) it exhibits a broad range of antiviral activity against primary HIV-1 isolates, multidrug resistant HIV-1 isolates, HIV-2, and simian immunodeficiency virus (SIV); (iii) it prevents transmigration of HIV-1 through human primary genital epithelial cells; (iv) it prevents HIV-1 transfer from dendritic cells to CD4+ T cells; (v) it is potent when added 2 h prior to addition of HIV-1 to target cells; (vi) it is potent at a low pH; (vii) it blocks HIV-1 infectivity when diluted in genital fluids; and (viii) it prevents herpes simplex virus infection. The heparan sulfate chains of the syndecan-Fc hybrid molecule are absolutely required for HIV-1 neutralization. Several lines of evidence suggest that the highly conserved Arg298 in the V3 region of gp120 serves as the locus for the syndecan-Fc hybrid molecule neutralization. In conclusion, this study suggests that the syndecan-Fc hybrid molecule represents the prototype of a new generation of microbicidal agents that may have promise for HIV-1 prevention. PMID:20439611

  17. A hingeless Fc fusion system for site-specific cleavage by IdeS.

    PubMed

    Novarra, Shabazz; Grinberg, Luba; Rickert, Keith W; Barnes, Arnita; Wilson, Susan; Baca, Manuel

    2016-01-01

    Fusion of proteins to the Fc region of IgG is widely used to express cellular receptors and other extracellular proteins, but cleavage of the fusion partner is sometimes required for downstream applications. Immunoglobulin G-degrading enzyme of Streptococcus pyogenes (IdeS) is a protease with exquisite specificity for human IgG, and it can also cleave Fc-fusion proteins at a single site in the N-terminal region of the CH2 domain. However, the site of IdeS cleavage results in the disulfide-linked hinge region partitioning with the released protein, complicating downstream usage of the cleaved product. To tailor the Fc fragment for release of partner proteins by IdeS treatment, we investigated the effect of deleting regions of IgG-derived sequence that are upstream of the cleavage site. Elimination of the IgG-derived hinge sequence along with several residues of the CH2 domain had negligible effects on expression and purity of the fusion protein, while retaining efficient processing by IdeS. An optimal Fc fragment comprising residues 235-447 of the human IgG1 heavy chain sufficed for efficient production of fusion proteins and minimized the amount of residual Ig-derived sequence on the cleavage product following IdeS treatment. Pairing of this truncated Fc fragment with IdeS cleavage enables highly specific cleavage of Fc-fusion proteins, thus eliminating the need to engineer extraneous cleavage sequences. This system should be helpful for producing Fc-fusion proteins requiring downstream cleavage, particularly those that are sensitive to internal miscleavage if treated with alternative proteases.

  18. Pharmacokinetics, Pharmacodynamics, and Efficacy of a Novel Long-Acting Human Growth Hormone: Fc Fusion Protein.

    PubMed

    Kim, Su Jin; Kwak, Hyun-Hee; Cho, Sung Yoon; Sohn, Young Bae; Park, Sung Won; Huh, Rimm; Kim, Jinsup; Ko, Ah-Ra; Jin, Dong-Kyu

    2015-10-01

    The current recombinant human growth hormone (rhGH) therapy requires daily subcutaneous (sc) injections, which results in poor patient compliance, especially in young children. To reduce the dosing frequency, we generated a chimeric protein of rhGH and the Fc-domain of immunoglobulin G (IgG) (rhGH-Fc). The pharmacokinetics and pharmacodynamics of sc-injected rhGH-Fc were assessed in male Sprague-Dawley rats and hypophysectomized rats, respectively. A single sc injection of rhGH-Fc at a dose of 0.2 mg/kg slowly reached a Cmax of 16.80 ng/mL and remained for 7 days with a half-life of 51.1 h. Conversely, a single sc injection of rhGH 0.2 mg/kg rapidly reached a Cmax of 46.88 ng/mL and declined with a half-life of 0.55 h to baseline values in 4 h. In the efficacy study, the sc-injected rhGH-Fc induced rapid weight gain and tibial width growth at a dose of 240 μg/animal. The effect of two injections of rhGH-Fc separated by 1 week was comparable to that of the same dose of 14 daily injections of rhGH. The rhGH-Fc is a novel candidate for long-acting rhGH therapy with more convenient weekly administration, as it reduces glomerular filtration and receptor-mediated clearance while allowing for the rapid reversal of potential adverse events.

  19. Vibsanin B preferentially targets HSP90β, inhibits interstitial leukocyte migration, and ameliorates experimental autoimmune encephalomyelitis.

    PubMed

    Ye, Bai-Xin; Deng, Xu; Shao, Li-Dong; Lu, Ying; Xiao, Run; Liu, Yi-Jie; Jin, Yi; Xie, Yin-Yin; Zhao, Yan; Luo, Liu-Fei; Ma, Shun; Gao, Ming; Zhang, Lian-Ru; He, Juan; Zhang, Wei-Na; Chen, Yi; Xia, Cheng-Feng; Deng, Min; Liu, Ting-Xi; Zhao, Qin-Shi; Chen, Sai-Juan; Chen, Zhu

    2015-05-01

    Interstitial leukocyte migration plays a critical role in inflammation and offers a therapeutic target for treating inflammation-associated diseases such as multiple sclerosis. Identifying small molecules to inhibit undesired leukocyte migration provides promise for the treatment of these disorders. In this study, we identified vibsanin B, a novel macrocyclic diterpenoid isolated from Viburnum odoratissimum Ker-Gawl, that inhibited zebrafish interstitial leukocyte migration using a transgenic zebrafish line (TG:zlyz-enhanced GFP). We found that vibsanin B preferentially binds to heat shock protein (HSP)90β. At the molecular level, inactivation of HSP90 can mimic vibsanin B's effect of inhibiting interstitial leukocyte migration. Furthermore, we demonstrated that vibsanin B ameliorates experimental autoimmune encephalomyelitis in mice with pathological manifestation of decreased leukocyte infiltration into their CNS. In summary, vibsanin B is a novel lead compound that preferentially targets HSP90β and inhibits interstitial leukocyte migration, offering a promising drug lead for treating inflammation-associated diseases.

  20. Fusion of the Fc part of human IgG1 to CD14 enhances its binding to gram-negative bacteria and mediates phagocytosis by Fc receptors of neutrophils.

    PubMed

    Vida, András; Bardoel, Bart; Milder, Fin; Majoros, László; Sümegi, Andrea; Bácsi, Attila; Vereb, György; van Kessel, Kok P M; van Strijp, Jos A G; Antal-Szalmás, Péter

    2012-08-30

    Microbial resistance to antimicrobial drugs is promoting a search for new antimicrobial agents that target highly conservative structures of pathogens. Human CD14 - a known pattern recognition receptor (PRR) which recognizes multiple ligands from different microbes might be a worthy candidate. The aim of our work was to create a CD14/Fc dimer protein and evaluate its whole bacteria binding and opsonizing capabilities. Fusion of CD14 with the fragment crystallisable (Fc) part of human IgG1 could not only lead to an artificial opsonin but the dimerization through the Fc part might also increase its affinity to different ligands. Human CD14 and the Fc part of human IgG1 was fused and expressed in HEK293 cells. A histidine tagged CD14 (CD14/His) was also expressed as control. Using flow cytometry we could prove that CD14/Fc bound to whole Gram-negative bacteria, especially to short lipopolysaccharide (Ra and Re) mutants, and weak interaction was observed between the fusion protein and Listeria monocytogenes. Other Gram-positive bacteria and fungi did not show any association with CD14/Fc. CD14/His showed about 50-times less potent binding to Gram-negative bacteria. CD14/Fc acted as an opsonin and enhanced phagocytosis of these bacteria by neutrophil granulocytes, monocyte-derived macrophages and dendritic cells. Internalization of bacteria was confirmed by trypan blue quenching and confocal microscopy. On neutrophils the Fc part of the fusion protein was recognized by Fc receptors (CD16, CD32), as determined by blocking experiments. CD14/Fc enhanced the killing of bacteria in an ex vivo whole blood assay. Our experiments confirm that PRR/Fc fusion proteins can give a boost to FcR dependent phagocytosis and killing provided the antimicrobial part binds efficiently to microbes.

  1. Indium-111 labeled leukocyte uptake: false-positive results in noninfected pseudoaneurysms

    SciTech Connect

    Gilbert, B.R.; Cerqueira, M.D.; Vea, H.W.; Nelp, W.B.

    1986-03-01

    Indium-111 (In-111) leukocyte scintigraphy was performed in two patients with postsurgical pseudoaneurysms as part of preoperative evaluation for evidence of graft infection. Despite positive In-111 uptake by the pseudoaneurysms, surgical and pathologic examinations failed to reveal any evidence of infection. The most likely explanation for the false-positive results is the labeling of contaminating platelets and erythrocytes in the leukocyte mixture. Caution must be exercised in interpretation of In-111 leukocyte scans in patients with postsurgical pseudoaneurysms.

  2. Individual radiosensitivity and its daily variations. [leukocyte reaction to epinephrine load

    NASA Technical Reports Server (NTRS)

    Druzhinin, Y. N.; Grigoryev, Y. G.; Podluzhnaya, G. N.; Pospishil, M.

    1974-01-01

    The effectiveness of determining individual radiosensitivity of rats by total gas exchange measurements, studies of Na/K content in urine, and the reaction of leukocytes to intra-abdominal administration of epinephrine, was studied. The most indicative results of predicting individual reaction to radiation were obtained by the leukocyte reaction to epinephrine load; however, changes in the leukocyte content of peripheral blood after epinephrine administration depended on the initial level during the day.

  3. Acute effects of radiation therapy on indium-111-labeled leukocyte uptake in bone marrow

    SciTech Connect

    Palestro, C.J.; Kim, C.K.; Vega, A.; Goldsmith, S.J. )

    1989-11-01

    We recently performed ({sup 99m}Tc)MDP bone and {sup 111}In-labeled leukocyte scintigraphy on a patient receiving radiation therapy to the lower cervical and upper thoracic spine. While the bone images revealed only minimally increased activity in the radiation port, leukocyte images revealed diffuse, intensely increased uptake in this same region. Radiation therapy should be included in the differential diagnosis of increased bone marrow activity on {sup 111}In leukocyte images.

  4. Immune-stimulatory effects of a bacteria-based probiotic on peripheral leukocyte subpopulations and cytokine mRNA expression levels in scouring holstein calves.

    PubMed

    Qadis, Abdul Qadir; Goya, Satoru; Yatsu, Minoru; Kimura, Atsushi; Ichijo, Toshihiro; Sato, Shigeru

    2014-05-01

    Subpopulations of peripheral leukocytes and cytokine mRNA expression levels were evaluated in scouring and healthy Holstein calves (age 10 ± 5 days; n=42) treated with a probiotic consisting of Lactobacillus plantarum, Enterococcus faecium and Clostridium butyricum. The calves were assigned to the scouring or healthy group and then subdivided into pathogen-positive treated (n=8), pathogen-positive control (n=8), pathogen-negative treated (n=6), pathogen-negative control (n=6), healthy treated (n=6) and healthy control (n=8) groups. A single dose of the probiotic (3.0 g/100 kg body weight) was given to each calf in the treatment groups for 5 days. Blood samples were collected on the first day of scour occurrence (day 0) and on day 7. In the scouring calves, smaller peripheral leukocyte subpopulations and cytokine mRNA expression levels were noted on day 0. The numbers of CD3(+) T cells; CD4(+), CD8(+) and WC1(+) γδ T cell subsets; and CD14(+), CD21(+) and CD282(+) (TLR2) cells were significantly increased in the scouring and healthy treated calves on day 7. Furthermore, interleukin-6, tumor necrosis factor-alpha and interferon-gamma mRNA expression was elevated in the peripheral leukocytes of the scouring and healthy treated calves on day 7. The scouring calves given the probiotic recovered on day 7. A significantly smaller number of peripheral leukocytes and lower cytokine mRNA expression level might be induced by scouring in calves. Repeated probiotic administration might stimulate cellular immunity and encourage recovery from scouring in pre-weaning Holstein calves. PMID:24451928

  5. Imaging of Leukocyte Trafficking in Alzheimer’s Disease

    PubMed Central

    Pietronigro, Enrica; Zenaro, Elena; Constantin, Gabriela

    2016-01-01

    Alzheimer’s disease (AD) is the most common neurodegenerative disorder and is characterized by a progressive decline of cognitive functions. The neuropathological features of AD include amyloid beta (Aβ) deposition, intracellular neurofibrillary tangles derived from the cytoskeletal hyperphosphorylated tau protein, amyloid angiopathy, the loss of synapses, and neuronal degeneration. In the last decade, inflammation has emerged as a key feature of AD, but most studies have focused on the role of microglia-driven neuroinflammation mechanisms. A dysfunctional blood–brain barrier has also been implicated in the pathogenesis of AD, and several studies have demonstrated that the vascular deposition of Aβ induces the expression of adhesion molecules and alters the expression of tight junction proteins, potentially facilitating the transmigration of circulating leukocytes. Two-photon laser scanning microscopy (TPLSM) has become an indispensable tool to dissect the molecular mechanisms controlling leukocyte trafficking in the central nervous system (CNS). Recent TPLSM studies have shown that vascular deposition of Aβ in the CNS promotes intraluminal neutrophil adhesion and crawling on the brain endothelium and also that neutrophils extravasate in the parenchyma preferentially in areas with Aβ deposits. These studies have also highlighted a role for LFA-1 integrin in neutrophil accumulation in the CNS of AD-like disease models, revealing that LFA-1 inhibition reduces the corresponding cognitive deficit and AD neuropathology. In this article, we consider how current imaging techniques can help to unravel new inflammation mechanisms in the pathogenesis of AD and identify novel therapeutic strategies to treat the disease by interfering with leukocyte trafficking mechanisms. PMID:26913031

  6. Fibrinogen modulates leukocyte recruitment in vivo during the acute inflammatory response.

    PubMed

    Vitorino de Almeida, V; Silva-Herdade, A; Calado, A; Rosário, H S; Saldanha, C

    2015-01-01

    Besides playing an important role in blood hemostases, fibrinogen also regulates leukocyte function in inflammation. Our previous in vitro studies showed that the adhesive behaviour of the neutrophil is modulated by soluble fibrinogen when present at a physiological concentration. This led us to propose that this plasma glycoprotein might further influence leukocyte recruitment in vivo and thus contribute to the inflammatory response. To address this in vivo, leukocyte recruitment was here investigated under acute inflammatory conditions in the absence of soluble fibrinogen in the blood circulation. For such, intravital microscopy on mesentery post-capillary venules was performed on homozygous fibrinogen α chain-deficient mice ((α-/-) mice). Acute inflammatory states were induced by perfusing platelet activating factor (PAF) over the exposed tissue. As control animals, two groups of mice expressing soluble fibrinogen in circulation were used, namely, C57BL/6 wild type animals and heterozygous fibrinogen α chain-deficient mice ((α+/-) mice). Under acute inflammatory conditions, an abnormal pattern of recruitment was observed for leukocytes in homozygous (α-/-) mice in comparison to both control groups. In fact, the former exhibited a significantly decreased number of rolling leukocytes that nevertheless, migrated with increased rolling velocities when compared to leukocytes from control animals. Consistently, homozygous mice further displayed a diminished number of adherent leukocytes than the other groups. Altogether our observations led us to conclude that leukocyte recruitment in homozygous (α-/-) mice is compromised what strongly suggests a role for soluble fibrinogen in leukocyte recruitment in inflammation.

  7. Nicotine induces leukocyte rolling and adhesion in the cerebral microcirculation of the mouse.

    PubMed

    Yong, T; Zheng, M Q; Linthicum, D S

    1997-12-01

    Nicotine and several related metabolites were examined for their ability to induce leukocyte rolling and adhesion in the cerebral microcirculation of the mouse. A cranial window was surgically prepared for the visualization of the pial microcirculation using an intra-vital microscopy imaging system. Using this technique rhodamine-labeled leukocytes could be visualized and video-recorded as they traveled within the microvessels, and the quantitation of their rolling and adhesion along the pial venule walls was assessed during an off-line video playback analysis. Nicotine was found to produce significant dose-related increases in leukocyte rolling and adhesion. Cotinine, a major nicotine metabolite, did not induce the same degree of leukocyte rolling and adhesion. Mecamylamine, a nicotine antagonist, was found to inhibit the nicotine-induced leukocyte rolling and adhesion. Anti-P-selectin antibody blocked nicotine-induced leukocyte rolling, while anti-CD18 antibody effectively inhibited leukocyte adhesion, but not rolling in similar experiments. Nicotine-induced leukocyte rolling and adhesion were also inhibited by superoxide dismutase and catalase. These data suggest that nicotine, the principle pharmacological agent in cigarette smoke and related tobacco products, acts via a ganglionic-type nicotinic receptor to enhance leukocyte rolling via P-selectin and reactive oxygen radical-dependent mechanisms in cerebral microcirculation of the mouse. PMID:9413272

  8. Kinetics of reversible-sequestration of leukocytes by the isolated perfused rat lung

    SciTech Connect

    Goliaei, B.

    1980-08-01

    The kinetics and morphology of sequestration and margination of rat leukocytes were studied using an isolated perfused and ventilated rat lung preparation. Whole rat blood, bone marrow suspension, or leukocyte suspensions, were used to perfuse the isolated rat lung. The lung was also perfused with latex particle suspensions and the passage of particles through the lung capillaries was studied. When a leukocyte suspension was perfused through the lung in the single-pass mode, the rate of sequestration decreased as more cells were perfused. In contrast, latex particles of a size comparable to that of leukocytes were totally stopped by the lung. When the leukocyte suspension was recirculated through the lung, cells were rapidly removed from circulation until a steady state was reached, after which no net removal of cells by the lung occurred. These results indicate that leukocytes are reversibly sequestered from circulation. The sequestered cells marginated and attached to the luminal surface of the endothelium of post-capillary venules and veins. A mathematical model was developed based on the assumption that the attachment and detachment of leukocytes to blood vessel walls follows first-order kinetics. The model correctly predicts the following characteristics of the system: (a) the kinetics of the sequestration of leukocytes by the lung; (b) the existence of a steady state when a suspension of leukocytes is recirculated through the lung; and (c) the independence of the fraction of cells remaining in circulation from the starting concentration for all values of starting concentration. (ERB)

  9. Different effects of anesthetics on spontaneous leukocyte rolling in rat skin.

    PubMed

    Janssen, G H; Tangelder, G J; oude Egbrink, M G; Reneman, R S

    1997-01-01

    In immunological reactions, leukocytes need to travel from the intravascular space through the vessel wall into the surrounding tissue. The first step in this process is leukocyte rolling, which has often been studied in anesthetized animals. In this study, we investigated the effect of pentobarbital, Hypnorm and both components of the latter, fentanyl and fluanisone, on this primary leukocyte-endothelial cell interaction. Using intravital brightfield video microscopy, observations were made in postcapillary venules in the intact skin of the nailfold of trained conscious Lewis rats. Subsequently, the animals were anesthetized and observations were made in vivo. Leukocyte rolling was significantly elevated after injection of Hypnorm or fentanyl, while pentobarbital and fluanisone had no effect. None of the anesthetics affected leukocyte rolling velocity. Blood flow was significantly increased only after injection of Hypnorm and fluanisone. No correlation existed between the relative changes in leukocyte rolling and concomitant changes in blood flow. The results show that the level of leukocyte rolling can be affected by anesthetics. These changes are probably not mediated by changes in local hemodynamics. Pentobarbital anesthesia does not influence leukocyte rolling. Therefore, pentobarbital is a suitable anesthetic for observation of leukocyte rolling in skin. Hypnorm significantly increases the level of rolling in skin venules. This effect seems to be caused mainly by fentanyl.

  10. How leukocytes trigger opening and sealing of gaps in the endothelial barrier

    PubMed Central

    Goswami, Debashree; Vestweber, Dietmar

    2016-01-01

    The entry of leukocytes into tissues requires well-coordinated interactions between the immune cells and endothelial cells which form the inner lining of blood vessels. The molecular basis for recognition, capture, and adhesion of leukocytes to the endothelial apical surface is well studied. This review will focus on recent advances in our understanding of events following the firm interaction of leukocytes with the inner surface of the blood vessel wall. We will discuss how leukocytes initiate the transmigration (diapedesis) process, trigger the opening of gaps in the endothelial barrier, and eventually move through this boundary. PMID:27703663

  11. BK Nephritis and Venous Thrombosis in Renal Transplant Recipient Detected by 111In Leukocyte Imaging.

    PubMed

    Pucar, Darko; Klein, Kandace; Corley, James; Williams, Hadyn T

    2015-07-01

    Three months after deceased donor kidney transplant, a patient who presented with proteinuric renal dysfunction and fever of undetermined origin was found to have BK viruria by quantitative polymerase chain reaction analysis. An ¹¹¹In leukocyte scan showed increased renal transplant uptake consistent with nephritis and linear uptake in the knee. Venous duplex ultrasound revealed acute occlusive thrombosis in the superficial right lesser saphenous vein in the area of increased radiolabeled leukocyte uptake. This ¹¹¹In leukocyte scan performed for fever of undetermined origin demonstrated findings of BK nephritis in a renal transplant patient and associated acute venous thrombosis related to leukocyte colonization.

  12. Phosphorylation of leukocyte PECAM and its association with detergent-resistant membranes regulate transendothelial migration.

    PubMed

    Florey, Oliver; Durgan, Joanne; Muller, William

    2010-08-01

    Leukocyte migration across the endothelial lining is a critical step in the body's response to infection and inflammation. The homophilic interaction between endothelial PECAM and leukocyte PECAM is essential for this process. The molecular events that are triggered in the endothelial cell by PECAM engagement have been well characterized; however, the function of leukocyte PECAM remains to be elucidated. To study this, we first blocked leukocyte transmigration using anti-PECAM Ab and then specifically activated leukocyte PECAM. This was sufficient to overcome the block and promote transmigration, suggesting an active signaling role for leukocyte PECAM. Consistent with this, we found that ligation of leukocyte PECAM induces phosphorylation of two tyrosine residues on its cytoplasmic tail. By performing RNA interference-rescue experiments, we demonstrate that these phosphorylation events are indispensable for transendothelial migration. Finally, we show that leukocyte PECAM translocates to a detergent-resistant membrane (DRM) during transmigration. PECAM localized in DRMs displays reduced phosphorylation and does not support transmigration. Together, these data support a model whereby engagement of leukocyte PECAM induces its transient tyrosine phosphorylation and induction of downstream signals that drive transmigration. These signals are then downregulated following PECAM translocation to DRMs. PMID:20581150

  13. How leukocytes trigger opening and sealing of gaps in the endothelial barrier

    PubMed Central

    Goswami, Debashree; Vestweber, Dietmar

    2016-01-01

    The entry of leukocytes into tissues requires well-coordinated interactions between the immune cells and endothelial cells which form the inner lining of blood vessels. The molecular basis for recognition, capture, and adhesion of leukocytes to the endothelial apical surface is well studied. This review will focus on recent advances in our understanding of events following the firm interaction of leukocytes with the inner surface of the blood vessel wall. We will discuss how leukocytes initiate the transmigration (diapedesis) process, trigger the opening of gaps in the endothelial barrier, and eventually move through this boundary.

  14. Raft coalescence and FcγRIIA activation upon sphingomyelin clustering induced by lysenin.

    PubMed

    Kulma, Magdalena; Kwiatkowska, Katarzyna; Sobota, Andrzej

    2012-08-01

    Activation of immunoreceptor FcγRIIA by cross-linking with antibodies is accompanied by coalescence of sphingolipid/cholesterol-rich membrane rafts leading to the formation of signaling platforms of the receptor. In this report we examined whether clustering of the raft lipid sphingomyelin can reciprocally induce partition of FcγRIIA to rafts. To induce sphingomyelin clustering, cells were exposed to non-lytic concentrations of GST-lysenin which specifically recognizes sphingomyelin. The lysenin/sphingomyelin complexes formed microscale assemblies composed of GST-lysenin oligomers engaging sphingomyelin of rafts. Upon sphingomyelin clustering, non-cross-linked FcγRIIA associated with raft-derived detergent-resistant membrane fractions as revealed by density gradient centrifugation. Pretreatment of cells with GST-lysenin also increased the size of detergent-insoluble molecular complexes of activated FcγRIIA. Sphingomyelin clustering triggered tyrosine phosphorylation of the receptor and its accompanying proteins, Cbl and NTAL, in the absence of receptor ligands and enhanced phosphorylation of these proteins in the ligand presence. These data indicate that clustering of plasma membrane sphingomyelin induces coalescence of rafts and triggers signaling events analogous to those caused by FcγRIIA activation.

  15. Structural Heterogeneity and Functional Domains of Murine Immunoglobulin G Fc Receptors

    NASA Astrophysics Data System (ADS)

    Ravetch, Jeffrey V.; Luster, Andrew D.; Weinshank, Richard; Kochan, Jarema; Pavlovec, Amalia; Portnoy, Daniel A.; Hulmes, Jeffrey; Pan, Yu-Ching E.; Unkeless, Jay C.

    1986-11-01

    Binding of antibodies to effector cells by way of receptors to their constant regions (Fc receptors) is central to the pathway that leads to clearance of antigens by the immune system. The structure and function of this important class of receptors on immune cells is addressed through the molecular characterization of Fc receptors (FcR) specific for the murine immunoglobulin G isotype. Structural diversity is encoded by two genes that by alternative splicing result in expression of molecules with highly conserved extracellular domains and different transmembrane and intracytoplasmic domains. The proteins encoded by these genes are members of the immunoglobulin supergene family, most homologous to the major histocompatibility complex molecule Eβ. Functional reconstitution of ligand binding by transfection of individual FcR genes demonstrates that the requirements for ligand binding are encoded in a single gene. These studies demonstrate the molecular basis for the functional heterogeneity of FcR's, accounting for the possible transduction of different signals in response to a single ligand.

  16. Biophysical stability of hyFc fusion protein with regards to buffers and various excipients.

    PubMed

    Lim, Jun Yeul; Kim, Nam Ah; Lim, Dae Gon; Eun, Chang-yong; Choi, Donghoon; Jeong, Seong Hoon

    2016-05-01

    A novel non-cytolytic hybrid Fc (hyFc) with an intact Ig structure without any mutation in the hyFc region, was developed to construct a long-acting agonistic protein. The stability of interleukin-7 (IL-7) fused with the hyFc (GXN-04) was evaluated to develop early formulations. Various biophysical methods were utilized and three different buffer systems with various pH ranges were investigated including histidine-acetate, sodium citrate, and tris buffers. Various excipients were incorporated into the systems to obtain optimum protein stability. Two evident thermal transitions were observed with the unfolding of IL-7 and hyFc. The Tm and ΔH increased with pH, suggesting increased conformational stability. Increased Z-average size with PDI and decreased zeta potential with pH increase, with the exception of tris buffer, showed aggregation issues. Moreover, tris buffer at higher pH showed aggregation peaks from DLS. Non-ionic surfactants were effective against agitation by outcompeting protein molecules for hydrophobic surfaces. Sucrose and sorbitol accelerated protein aggregation during agitation, but exhibited a protective effect against oxidation, with preferential exclusion favoring the compact states of GXN-04. The stability of GXN-04 was varied by basal buffers and excipients, hence the buffers and excipients need to be evaluated carefully to achieve the maximum stability of proteins. PMID:26851357

  17. Targeting a homogeneously glycosylated antibody Fc to bind cancer cells using a synthetic receptor ligand.

    PubMed

    Xiao, Junpeng; Chen, Rui; Pawlicki, Mark A; Tolbert, Thomas J

    2009-09-30

    The targeting of a glycosylated antibody Fc fragment to bind to cancer cells by site-selective incorporation of a synthetic ligand is described. Homogeneously glycosylated immunoglobulin G subclass 1 fragment crystallizable (IgG1 Fc) was produced by expression in a glycosylation-deficient yeast strain and subsequent treatment with mannosidase IA. A N-terminal cysteine was generated on the expressed IgG1 Fc by utilizing proteolytic processing enzymes in the yeast secretory pathway. A cyclic RGD peptide thioester 2 was synthesized and then site-selectively attached to the N-terminus of the IgG1 Fc glycoprotein using native chemical ligation. The resulting chemically modified antibody fragment, RGD-Man(5)-IgG1 Fc (5), retained biological activity similar to that of the free cyclic RGD peptide 1 when assayed for its ability to both promote and inhibit the adhesion of alpha(v)beta(3) integrin receptor-expressing WM-115 melanoma cells. In addition, fluorescent microscopy experiments were conducted using FITC-labeled 5 and confirmed binding of 5 to WM-115 melanoma cells. Site-selectively modified antibody fragments such as the one described here may be used to combine the beneficial properties of synthetic receptor ligands with antibody fragments to develop useful biochemical tools and improved therapeutics. The methods described here can also be used to produce glycoprotein fragments for the chemoenzymatic synthesis of homogeneous glycoproteins.

  18. Columnar Processing in Primate pFC: Evidence for Executive Control Microcircuits

    PubMed Central

    Opris, Ioan; Hampson, Robert E.; Gerhardt, Greg A.; Berger, Theodore W.; Deadwyler, Sam A.

    2013-01-01

    A common denominator for many cognitive disorders of human brain is the disruption of neural activity within pFC, whose structural basis is primarily interlaminar (columnar) microcircuits or “mini-columns.” The importance of this brain region for executive decision-making has been well documented; however, because of technological constraints, the minicolumnar basis is not well understood. Here, via implementation of a unique conformal multielectrode recording array, the role of interlaminar pFC minicolumns in the executive control of task-related target selection is demonstrated in nonhuman primates performing a visuomotor DMS task. The results reveal target-specific, interlaminar correlated firing during the decision phase of the trial between multielectrode recording array-isolated minicolumnar pairs of neurons located in parallel in layers 2/3 and layer 5 of pFC. The functional significance of individual pFC minicolumns (separated by 40 μm) was shown by reduced correlated firing between cell pairs within single minicolumns on error trials with inappropriate target selection. To further demonstrate dependence on performance, a task-disrupting drug (cocaine) was administered in the middle of the session, which also reduced interlaminar firing in minicolumns that fired appropriately in the early (nondrug) portion of the session. The results provide a direct demonstration of task-specific, real-time columnar processing in pFC indicating the role of this type of microcircuit in executive control of decision-making in primate brain. PMID:23016850

  19. Pharmacokinetic models for FcRn-mediated IgG disposition.

    PubMed

    Xiao, Jim J

    2012-01-01

    The objectives were to review available PK models for saturable FcRn-mediated IgG disposition, and to explore an alternative semimechanistic model. Most available empirical and mechanistic PK models assumed equal IgG concentrations in plasma and endosome in addition to other model-specific assumptions. These might have led to inappropriate parameter estimates and model interpretations. Some physiologically based PK (PBPK) models included FcRn-mediated IgG recycling. The nature of PBPK models requires borrowing parameter values from literature, and subtle differences in the assumptions may render dramatic changes in parameter estimates related to the IgG recycling kinetics. These models might have been unnecessarily complicated to address FcRn saturation and nonlinear IgG PK especially in the IVIG setting. A simple semimechanistic PK model (cutoff model) was developed that assumed a constant endogenous IgG production rate and a saturable FcRn-binding capacity. The FcRn-binding capacity was defined as MAX, and IgG concentrations exceeding MAX in endosome resulted in lysosomal degradation. The model parameters were estimated using simulated data from previously published models. The cutoff model adequately described the rat and mouse IgG PK data simulated from published models and allowed reasonable estimation of endogenous IgG turnover rates.

  20. Columnar processing in primate pFC: evidence for executive control microcircuits.

    PubMed

    Opris, Ioan; Hampson, Robert E; Gerhardt, Greg A; Berger, Theodore W; Deadwyler, Sam A

    2012-12-01

    A common denominator for many cognitive disorders of human brain is the disruption of neural activity within pFC, whose structural basis is primarily interlaminar (columnar) microcircuits or "minicolumns." The importance of this brain region for executive decision-making has been well documented; however, because of technological constraints, the minicolumnar basis is not well understood. Here, via implementation of a unique conformal multielectrode recording array, the role of interlaminar pFC minicolumns in the executive control of task-related target selection is demonstrated in nonhuman primates performing a visuomotor DMS task. The results reveal target-specific, interlaminar correlated firing during the decision phase of the trial between multielectrode recording array-isolated minicolumnar pairs of neurons located in parallel in layers 2/3 and layer 5 of pFC. The functional significance of individual pFC minicolumns (separated by 40 μm) was shown by reduced correlated firing between cell pairs within single minicolumns on error trials with inappropriate target selection. To further demonstrate dependence on performance, a task-disrupting drug (cocaine) was administered in the middle of the session, which also reduced interlaminar firing in minicolumns that fired appropriately in the early (nondrug) portion of the session. The results provide a direct demonstration of task-specific, real-time columnar processing in pFC indicating the role of this type of microcircuit in executive control of decision-making in primate brain. PMID:23016850

  1. Longitudinal evaluation of leukocyte transcripts in killer whales (Orcinus Orca)

    USGS Publications Warehouse

    Sitt, Tatjana; Bowen, Lizabeth; Lee, Chia-Shan; Blanchard, Myra; McBain, James; Dold, Christopher; Stott, Jeffrey L.

    2016-01-01

    Early identification of illness and/or presence of environmental and/or social stressors in free-ranging and domestic cetaceans is a priority for marine mammal health care professionals. Incorporation of leukocyte gene transcript analysis into the diagnostic tool kit has the potential to augment classical diagnostics based upon ease of sample storage and shipment, inducible nature and well-defined roles of transcription and associated downstream actions. Development of biomarkers that could serve to identify “insults” and potentially differentiate disease etiology would be of great diagnostic value. To this end, a modest number of peripheral blood leukocyte gene transcripts were selected for application to a domestic killer whale population with a focus on broad representation of inducible immunologically relevant genes. Normalized leukocyte transcript values, longitudinally acquired from 232 blood samples derived from 26 clinically healthy whales, were not visibly influenced temporally nor by sex or the specific Park in which they resided. Stability in leukocyte transcript number during periods of health enhances their potential use in diagnostics through identification of outliers. Transcript levels of two cytokine genes, IL-4 and IL-17, were highly variable within the group as compared to the other transcripts. IL-4 transcripts were typically absent. Analysis of transcript levels on the other genes of interest, on an individual animal basis, identified more outliers than were visible when analyzed in the context of the entire population. The majority of outliers (9 samples) were low, though elevated transcripts were identified for IL-17 from 2 animals and one each for Cox-2 and IL-10. The low number of outliers was not unexpected as sample selection was intentionally directed towards animals that were clinically healthy at the time of collection. Outliers may reflect animals experiencing subclinical disease that is transient and self-limiting. The

  2. Longitudinal evaluation of leukocyte transcripts in killer whales (Orcinus Orca).

    PubMed

    Sitt, Tatjana; Bowen, Lizabeth; Lee, Chia-Shan; Blanchard, Myra T; McBain, James; Dold, Christopher; Stott, Jeffrey L

    2016-07-01

    Early identification of illness and/or presence of environmental and/or social stressors in free-ranging and domestic cetaceans is a priority for marine mammal health care professionals. Incorporation of leukocyte gene transcript analysis into the diagnostic tool kit has the potential to augment classical diagnostics based upon ease of sample storage and shipment, inducible nature and well-defined roles of transcription and associated downstream actions. Development of biomarkers that could serve to identify "insults" and potentially differentiate disease etiology would be of great diagnostic value. To this end, a modest number of peripheral blood leukocyte gene transcripts were selected for application to a domestic killer whale population with a focus on broad representation of inducible immunologically relevant genes. Normalized leukocyte transcript values, longitudinally acquired from 232 blood samples derived from 26 clinically healthy whales, were not visibly influenced temporally nor by sex or the specific Park in which they resided. Stability in leukocyte transcript number during periods of health enhances their potential use in diagnostics through identification of outliers. Transcript levels of two cytokine genes, IL-4 and IL-17, were highly variable within the group as compared to the other transcripts. IL-4 transcripts were typically absent. Analysis of transcript levels on the other genes of interest, on an individual animal basis, identified more outliers than were visible when analyzed in the context of the entire population. The majority of outliers (9 samples) were low, though elevated transcripts were identified for IL-17 from 2 animals and one each for Cox-2 and IL-10. The low number of outliers was not unexpected as sample selection was intentionally directed towards animals that were clinically healthy at the time of collection. Outliers may reflect animals experiencing subclinical disease that is transient and self-limiting. The immunologic

  3. Longitudinal evaluation of leukocyte transcripts in killer whales (Orcinus Orca).

    PubMed

    Sitt, Tatjana; Bowen, Lizabeth; Lee, Chia-Shan; Blanchard, Myra T; McBain, James; Dold, Christopher; Stott, Jeffrey L

    2016-07-01

    Early identification of illness and/or presence of environmental and/or social stressors in free-ranging and domestic cetaceans is a priority for marine mammal health care professionals. Incorporation of leukocyte gene transcript analysis into the diagnostic tool kit has the potential to augment classical diagnostics based upon ease of sample storage and shipment, inducible nature and well-defined roles of transcription and associated downstream actions. Development of biomarkers that could serve to identify "insults" and potentially differentiate disease etiology would be of great diagnostic value. To this end, a modest number of peripheral blood leukocyte gene transcripts were selected for application to a domestic killer whale population with a focus on broad representation of inducible immunologically relevant genes. Normalized leukocyte transcript values, longitudinally acquired from 232 blood samples derived from 26 clinically healthy whales, were not visibly influenced temporally nor by sex or the specific Park in which they resided. Stability in leukocyte transcript number during periods of health enhances their potential use in diagnostics through identification of outliers. Transcript levels of two cytokine genes, IL-4 and IL-17, were highly variable within the group as compared to the other transcripts. IL-4 transcripts were typically absent. Analysis of transcript levels on the other genes of interest, on an individual animal basis, identified more outliers than were visible when analyzed in the context of the entire population. The majority of outliers (9 samples) were low, though elevated transcripts were identified for IL-17 from 2 animals and one each for Cox-2 and IL-10. The low number of outliers was not unexpected as sample selection was intentionally directed towards animals that were clinically healthy at the time of collection. Outliers may reflect animals experiencing subclinical disease that is transient and self-limiting. The immunologic

  4. Measurement of oxyradicals from leukocytes lodged in a microchannel array

    NASA Astrophysics Data System (ADS)

    Kikuchi, Yuji; Kikuchi, Hiroko E.

    2001-05-01

    The oxyradical production by leukocytes is crucial for killing invading bacteria, while it has been widely discussed as a tissue injuring factor. Despite such importance of the event, it is still unclear, probably because of lack of simple and reliable measurement methods, to what extent it varies among different subjects and either to what extent it is affected by environmental factors including diet. The present paper describes use of microfabricated channel arrays, that have been developed for use in studies of blood rheology, in the oxyradical measurement by chemiluminescence.

  5. Production of antibodies which recognize opiate receptors on murine leukocytes

    SciTech Connect

    Carr, D.J.J.; Bost, K.L.; Blalock, J.E.

    1988-01-01

    An antibody has been developed which recognizes opiate receptors on cells of the immune system. This antibody blocks specific binding of the radiolabeled opiate receptor ligand, /sup 3/H-dihydromorphine, to receptors on murine splenocytes. Additionally, the anti-receptor antibody competes with ..beta..-endorphin, meta-enkephalin, and naloxone for the same binding site on the leukocytes. Moreover, the anti-receptor antibody possesses agonist activity similar to ..beta..-endorphin in suppressing cAMP production by lymphocytes. These results suggest the development of an antibody which recognizes classical opiate receptors on cells of the immune system.

  6. Theileria-transformed bovine leukocytes have cancer hallmarks.

    PubMed

    Tretina, Kyle; Gotia, Hanzel T; Mann, David J; Silva, Joana C

    2015-07-01

    The genus Theileria includes tick-transmitted apicomplexan parasites of ruminants with substantial economic impact in endemic countries. Some species, including Theileria parva and Theileria annulata, infect leukocytes where they induce phenotypes that are shared with some cancers, most notably immortalization, hyperproliferation, and dissemination. Despite considerable research into the affected host signaling pathways, the parasite proteins directly responsible for these host phenotypes remain unknown. In this review we outline current knowledge on the manipulation of host cells by transformation-inducing Theileria, and we propose that comparisons between cancer biology and host-Theileria interactions can reveal chemotherapeutic targets against Theileria-induced pathogenesis based on cancer treatment approaches.

  7. The Study of Leukocyte Functions in a Rotating Wall Vessel

    NASA Technical Reports Server (NTRS)

    Trial, JoAnn

    1998-01-01

    The objective of this study was to investigate the behavior of leukocytes under free-fall conditions in a rotating wall vessel. In such a vessel, the tendency of a cell to fall in response to gravity is opposed by the rotation of the vessel and the culture medium within, keeping the cells in suspension without fluid shear. Previous reports indicated that such functions as lymphocyte migration through collagen matrix or monocyte cytokine secretion are altered under these conditions, and these changes correlate with similar functional defects of cultured cells seen during spaceflight.

  8. Are soluble factors relevant for polymorphonuclear leukocyte dysregulation in septicemia?

    PubMed Central

    Wenisch, C; Graninger, W

    1995-01-01

    Polymorphonuclear leukocytes (PMNs) of twelve patients with gram-negative septicemia exhibited a decreased capacity to phagocytize Escherichia coli and generate reactive oxygen products which normalized within 7 days of treatment. Ex vivo exchange of plasma from age-, sex-, and blood-group-identical normal controls resulted in an increase of both phagocytic capacity and reactive oxygen intermediate generation in PMNs of septicemic patients and transiently reduced phagocytosis and reactive oxygen intermediate production in PMNs of normal controls. These results suggest that extrinsic factors are crucial for PMN function. PMID:7697538

  9. Theileria-transformed bovine leukocytes have cancer hallmarks.

    PubMed

    Tretina, Kyle; Gotia, Hanzel T; Mann, David J; Silva, Joana C

    2015-07-01

    The genus Theileria includes tick-transmitted apicomplexan parasites of ruminants with substantial economic impact in endemic countries. Some species, including Theileria parva and Theileria annulata, infect leukocytes where they induce phenotypes that are shared with some cancers, most notably immortalization, hyperproliferation, and dissemination. Despite considerable research into the affected host signaling pathways, the parasite proteins directly responsible for these host phenotypes remain unknown. In this review we outline current knowledge on the manipulation of host cells by transformation-inducing Theileria, and we propose that comparisons between cancer biology and host-Theileria interactions can reveal chemotherapeutic targets against Theileria-induced pathogenesis based on cancer treatment approaches. PMID:25951781

  10. High resolution VESTA LAMO atlas derived from Dawn FC images.

    NASA Astrophysics Data System (ADS)

    Roatsch, Thomas; Kersten, Elke; Matz, Klaus-Dieter; Preusker, Frank; Scholten, Frank; Jaumann, Ralf; Raymond, Carol A.; Russell, Cris T.

    2013-04-01

    Introduction: NASA's Dawn spacecraft entered orbit of the inner main belt asteroid 4 Vesta on July 16, 2011, and spent about one year in orbit to characterize the geology, elemental and mineralogical composition, topography, shape, and internal structure of Vesta before it departed to asteroid 1 Ceres in late 2012. One of the major goals of the mission was a global mapping of Vesta. Data: The DAWN mission was mapping Vesta from three different orbit heights during Survey orbit (3100 km altitude), HAMO (High Altitude Mapping Orbit, 700 km altitude), and LAMO (Low Altitude Mapping Orbit, 210 km altitude) [1]. The Dawn mission is equipped with a framing camera (FC) [2] which was the prime instrument during the LAMO phase. DAWN orbited Vesta during LAMO in 21 cycles between December 2011 and end of April 2012. The framing camera took about 10,000 clear filter images with a resolution of about 20 m/pixel during these cycles. The images were taken with different viewing angles and different illumination conditions. We selected about 8,000 images for the global coverage of Vesta. Data Processing: The first step of the processing chain is to ortho rectify the images to the proper scale and map projection type. This process requires detailed high-resolution information of the local topography of Vesta. The global topgraphy was calculated during the stereo processing of the HAMO images [3] and was used here. The shape model was used for the calculation of the ray intersection points while the map projection itself was done onto a sphere with a mean radius of 255 km. The next step was the mosaicking of all images to one global mosaic of Vesta, the so called basemap. Vesta map tiles: The Vesta atlas was produced in a scale of 1:200,000 and consists of 30 tiles that conform to the quadrangle scheme proposed by Greeley and Batson [4] and is used for example for mapping Mars in a scale of 1:5,000,000. A map scale of 1:200,000 guarantees a mapping at the highest available DAWN

  11. TGEV infection up-regulates FcRn expression via activation of NF-κB signaling

    PubMed Central

    Guo, Jinyue; Li, Fei; Qian, Shaoju; Bi, Dingren; He, Qigai; Jin, Hui; Luo, Rui; Li, Shaowen; Meng, Xianrong; Li, Zili

    2016-01-01

    It has been well characterized that the neonatal Fc receptor (FcRn) transports maternal IgG to a fetus or newborn and protects IgG from degradation. We previously reported that FcRn is expressed in a model of normal porcine intestinal epithelial cells (IPEC-J2). Transmissible gastroenteritis is an acute enteric disease of swine that is caused by transmissible gastroenteritis virus (TGEV). How porcine FcRn (pFcRn) expression is regulated by pathogenic infection remains unknown. Our research shows that IPEC-J2 cells infected with TGEV had up-regulated pFcRn expression. In addition, the NF-κB signaling pathway was activated in IPEC-J2 cells by TGEV infection. Furthermore, treatment of TGEV-infected IPEC-J2 cells with the NF-κB-specific inhibitor BAY 11-7082 resulted in down-regulation of pFcRn expression. Transient transfection of pFcRn promoter luciferase report plasmids with overexpression of NF-κB p65 transcription factor enhanced the activation of the luciferase report plasmids. We identified four NF-κB transcription factor binding sites in the promoter region of this gene using luciferase reporter system, chromatin immunoprecipitation, electromobility shift assay, and supershift analysis. Together, the data provide the first evidence that TGEV infection up-regulates pFcRn expression via activation of NF-κB signaling. PMID:27555521

  12. Galactosylation of IgG1 modulates FcγRIIB-mediated inhibition of murine autoimmune hemolytic anemia.

    PubMed

    Yamada, Kazunori; Ito, Kiyoaki; Furukawa, Jun-Ichi; Nakata, Junichiro; Alvarez, Montserrat; Verbeek, J Sjef; Shinohara, Yasuro; Izui, Shozo

    2013-12-01

    Murine immune effector cells express three different stimulatory FcγRs (FcγRI, FcγRIII and FcγRIV) and one inhibitory receptor, FcγRIIB. Competitive engagement of stimulatory and inhibitory FcγRs has been shown to be critical for the development of immune complex-mediated inflammatory disorders. Because of the previous demonstration that FcγRIIB was unable to inhibit FcγRIII-mediated autoimmune hemolytic anemia induced by 105-2H IgG1 anti-RBC mAb, we reevaluated the regulatory role of FcγRIIB on the development of anemia using two additional IgG1 anti-RBC mAbs (34-3C and 3H5G1) and different 34-3C IgG subclass-switch variants. We were able to induce a more severe anemia in FcγRIIB-deficient mice than in FcγRIIB-sufficient mice after injection of 34-3C and 3H5G1 IgG1, but not 105-2H IgG1. Structural analysis of N-linked oligosaccharides attached to the CH2 domain revealed that 105-2H was poorly galactosylated as compared with the other mAbs, while the extent of sialylation was comparable between all mAbs. In addition, we observed that a more galactosylated 105-2H variant provoked more severe anemia in FcγRIIB-deficient mice than FcγRIIB-sufficient mice. In contrast, the development of anemia induced by three non-IgG1 subclass variants of the 34-3C mAb was not down-regulated by FcγRIIB, although they were more galactosylated than its IgG1 variant. These data indicate that FcγRIIB-mediated inhibition of autoimmune hemolytic anemia is restricted to the IgG1 subclass and that galactosylation, but not sialylation, of IgG1 (but not other IgG subclasses) is critical for the interaction with FcγR, thereby determining the pathogenic potential of IgG1 autoantibodies.

  13. FINE CULM1 (FC1) Works Downstream of Strigolactones to Inhibit the Outgrowth of Axillary Buds in Rice

    PubMed Central

    Minakuchi, Kosuke; Kameoka, Hiromu; Yasuno, Naoko; Umehara, Mikihisa; Luo, Le; Kobayashi, Kaoru; Hanada, Atsushi; Ueno, Kotomi; Asami, Tadao; Yamaguchi, Shinjiro; Kyozuka, Junko

    2010-01-01

    Recent studies of highly branched mutants of pea, Arabidopsis and rice have demonstrated that strigolactones (SLs) act as hormones that inhibit shoot branching. The identification of genes that work downstream of SLs is required for a better understanding of how SLs control the growth of axillary buds. We found that the increased tillering phenotype of fine culm1 (fc1) mutants of rice is not rescued by the application of 1 μM GR24, a synthetic SL analog. Treatment with a high concentration of GR24 (10 μM) causes suppression of tiller growth in wild-type plants, but is not effective on fc1 mutants, implying that proper FC1 functioning is required for SLs to inhibit bud growth. Overexpression of FC1 partially rescued d3-2 defects in the tiller growth and plant height. An in situ hybridization analysis showed that FC1 mRNA accumulates in axillary buds, the shoot apical meristem, young leaves, vascular tissues and the tips of crown roots. FC1 mRNA expression was not significantly affected by GR24, suggesting that transcriptional induction may not be the mechanism by which SLs affect FC1 functioning. On the other hand, the expression level of FC1 is negatively regulated by cytokinin treatment. We propose that FC1 acts as an integrator of multiple signaling pathways and is essential to the fine-tuning of shoot branching in rice. PMID:20547591

  14. pH-dependent binding engineering reveals an FcRn affinity threshold that governs IgG recycling.

    PubMed

    Borrok, M Jack; Wu, Yanli; Beyaz, Nurten; Yu, Xiang-Qing; Oganesyan, Vaheh; Dall'Acqua, William F; Tsui, Ping

    2015-02-13

    The Fc domain of IgG has been the target of multiple mutational studies aimed at altering the pH-dependent IgG/FcRn interaction to modulate IgG pharmacokinetics. These studies have yielded antibody variants with disparate pharmacokinetic characteristics, ranging from extended in vivo half-life to those exhibiting extremely rapid clearance. To better understand pH-dependent binding parameters that govern these outcomes and limit FcRn-mediated half-life extension, we generated a panel of novel Fc variants with high affinity binding at acidic pH that vary in pH 7.4 affinities and assessed pharmacokinetic outcomes. Pharmacokinetic studies in human FcRn transgenic mice and cynomolgus monkeys showed that multiple variants with increased FcRn affinities at acidic pH exhibited extended serum half-lives relative to the parental IgG. Importantly, the results reveal an underappreciated affinity threshold of neutral pH binding that determines IgG recycling efficiency. Variants with pH 7.4 FcRn affinities below this threshold recycle efficiently and can exhibit increased serum persistence. Increasing neutral pH FcRn affinity beyond this threshold reduced serum persistence by offsetting the benefits of increased pH 6.0 binding. Ultra-high affinity binding to FcRn at both acidic and neutral pH leads to rapid serum clearance.

  15. Characterization of the promoter of the human gene encoding the high-affinity IgG receptor: Transcriptional induction by. gamma. -interferon is mediated through common DNA response elements

    SciTech Connect

    Pearse, R.N.; Feinman, R.; Ravetch, J.V. )

    1991-12-15

    Expression of the high-affinity receptor for IgG (Fc{sub {gamma}}RI) is restricted to cells of myeloid lineage and is induced by {gamma}-interferon (IFN-{gamma}) but not by IFN-{alpha}/{beta}. The organization of the human Fc{sub {gamma}}RI gene has been determined and the DNA elements governing its cell type-restricted transcription and IFN-{gamma} induction are reported here. A 39-nucleotide sequence (IFN-{gamma} response region, or GRR) is defined that is both necessary and sufficient for IFN-{gamma} inducibility. Sequence analysis of the GRR reveals the presence of promoter elements initially defined for the major histocompatibility complex class 2 genes: i.e., X, H, and {gamma}-IRE sequences. Comparison of a number of genes whose expression is induced selectively by IFN-{gamma} indicated that the presence of these elements is a general feature of IFN-{gamma}-responsive genes. The studies suggest that the combination of X, H, and {gamma}-IRE elements is a common motif in the pathway of transcriptional induction by this lymphokine.

  16. gamma-Hexachlorocyclohexane (gamma-HCH)

    Integrated Risk Information System (IRIS)

    gamma - Hexachlorocyclohexane ( gamma - HCH ) ; CASRN 58 - 89 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Asse

  17. Photoperiod affects the expression of sex and species differences in leukocyte number and leukocyte trafficking in congeneric hamsters.

    PubMed

    Bilbo, S D; Dhabhar, F S; Viswanathan, K; Saul, A; Nelson, R J

    2003-11-01

    Sex differences in immune function are well documented. These sex differences may be modulated by social and environmental factors. Individuals of polygynous species generally exhibit more pronounced sex differences in immune parameters than individuals of monogamous species, often displaying an energetic trade-off between enhanced immunity and high mating success. During winter, animals contend with environmental conditions (e.g. low temperatures and decreased food availability) that evoke energetic-stress responses; many mammals restrict reproduction in response to photoperiod as part of an annual winter coping strategy. To test the hypothesis that extant sex and species differences in immune surveillance may be modulated by photoperiod, we examined leukocyte numbers in males and females of two closely related hamster species (Phodopus). As predicted, uniparental P. sungorus exhibited a robust sex difference, with total white blood cells, total lymphocytes, T cells, and B cells higher in females than males, during long days when reproduction occurs, but not during short days when reproduction usually stops. In contrast, biparental male and female P. campbelli exhibited comparable leukocyte numbers during both long and short days. To study sex differences in stress responses, we also examined immune cell trafficking in response to an acute (2 h) restraint stressor. During stressful challenges, it appears beneficial for immune cells to exit the blood and move to primary immune defense areas such as the skin, in preparation for potential injury or infection. Acute stress moved lymphocytes and monocytes out of the blood in all animals. Blood cortisol concentrations were increased in P. sungorus females compared to males at baseline (52%) and in response to restraint stress (38%), but only in long days. P. campbelli males and females exhibited comparable blood cortisol and stress responses during both long and short days. Our results suggest that interactions among

  18. An Fc Domain Protein–Small Molecule Conjugate as an Enhanced Immunomodulator

    PubMed Central

    2015-01-01

    Proteins as well as small molecules have demonstrated success as therapeutic agents, but their pharmacologic properties sometimes fall short against particular drug targets. Although the adenosine 2a receptor (A2AR) has been identified as a promising target for immunotherapy, small molecule A2AR agonists have suffered from short pharmacokinetic half-lives and the potential for toxicity by modulating nonimmune pathways. To overcome these limitations, we have tethered the A2AR agonist CGS-21680 to the immunoglobulin Fc domain using expressed protein ligation with Sf9 cell secreted protein. The protein small molecule conjugate Fc-CGS retained potent Fc receptor and A2AR interactions and showed superior properties as a therapeutic for the treatment of a mouse model of autoimmune pneumonitis. This approach may provide a general strategy for optimizing small molecule therapeutics. PMID:24533830

  19. Nanodomains in Early and Later Phases of FcεRI Signaling

    PubMed Central

    Holowka, David; Baird, Barbara

    2014-01-01

    Our long term efforts to elucidate receptor-mediated signaling in immune cells, particularly transmembrane signaling initiated by the receptor (FcεRI) for immunoglobulin E (IgE) in mast cells, led us unavoidably to contemplate the role of the heterogeneous plasma membrane. Our early investigations with fluorescence microscopy revealed co-redistribution of certain lipids and signaling components with antigen-crosslinked IgE-FcεRI and pointed to participation of ordered membrane domains in the signaling process. With a focus on this function, we have worked along with others to develop diverse and increasingly sophisticated tools to analyze the complexity of membrane structure that facilitates regulation and targeting of signaling events. This essay describes how initial membrane interactions of clustered IgE-FcεRI lead to downstream cellular responses and how biochemical information integrated with nanoscale resolution spectroscopy and imaging is providing mechanistic insights at the level of molecular complexes. PMID:25658351

  20. Activation of antibody Fc function by antigen-induced conformational changes.

    PubMed Central

    Brown, J C; Koshland, M E

    1975-01-01

    IgM antibody directed against the pheny-beta-lactoside hapten was examined for its capacity to fix complement in the presence of the hapten, monohapten-substituted antigen, and multihapten-substituted antigen. Hapten was found to have no effect; monovalent antigen induced an excellent response which could be inhibited by hapten; and multivalent antigen also induced an excellent response which was related to the number of determinants added and not to the formation of antigen-antibody aggregates. The difference between the activities of hapten and monovalent antigen was reflected in their affinities for the IgM antibody. The monovalent antigen had a lower Ka, indicating that energy from binding was used to activate the Fc complement binding sites. These data show that the expression of IgM Fc function depends on a change in Fc conformation produced by the binding of antigen at the distant Fab combining sites. PMID:1061094

  1. Activation of antibody Fc function by antigen-induced conformational changes.

    PubMed

    Brown, J C; Koshland, M E

    1975-12-01

    IgM antibody directed against the pheny-beta-lactoside hapten was examined for its capacity to fix complement in the presence of the hapten, monohapten-substituted antigen, and multihapten-substituted antigen. Hapten was found to have no effect; monovalent antigen induced an excellent response which could be inhibited by hapten; and multivalent antigen also induced an excellent response which was related to the number of determinants added and not to the formation of antigen-antibody aggregates. The difference between the activities of hapten and monovalent antigen was reflected in their affinities for the IgM antibody. The monovalent antigen had a lower Ka, indicating that energy from binding was used to activate the Fc complement binding sites. These data show that the expression of IgM Fc function depends on a change in Fc conformation produced by the binding of antigen at the distant Fab combining sites.

  2. Construction of Mycobacterium tuberculosis ESAT-6 fused to human Fcγ of IgG1: To target FcγR as a delivery system for enhancement of immunogenicity.

    PubMed

    Soleimanpour, Saman; Mohammadi, Mohammad Ali; Ghazvini, Kiarash; Jamehdar, Saeid Amel; Sadeghian, Hamid; Taghiabadi, Mahboubeh; Rezaee, S A R

    2016-04-15

    In order to prevent spreading of Mycobacterium tuberculosis (Mtb), it is necessary to discover effective vaccines, fast and reliable diagnosis, and appropriate treatment schemes. In the present study, an Fc-tagged recombinant Mtb-ESAT-6 was produced to make a selective delivery system for promoting cellular immunity. To determine 3D structure of the recombinant protein, model building was performed in MODELLER9v13 program. After preparation of Mtb-DNA and Fcγ1 cDNA, they were amplified by specific primers to make ESAT-6 and Fcγ1 products to fuse them in frame using splicing by overlap extension (SOEing)-PCR. After TA cloning, the construct was sequenced to confirm no errors have been introduced. The recombinant DNA was then subcloned into PDR2EF1α eukaryotic expression vector. The plasmid sequenced over the sites at which two DNA fragments were cloned to ensure that the ligation had generated an in-frame fusion of the genes. The CHO cells were then stably transected by PDR2EF1α-ESAT-6:Fcγ1 vector using lipofectamin and the expression and its binding to the Fcγ receptor (FcγRI) on APCs were confirmed by immunofluorescence assay (IFA). The IFA results demonstrated that ESAT6:Fcγ1 was expressed in engineered CHO cells. Semi-scale protein production and purification using HiTrap-PA column showed a high secretion of the recombinant protein by Western blotting method. The molecular weight of the monomer in the SDS-PAGE was equal to a protein of 50kDa, which dimerizes by disulfide bond of Fcγ fragments. Since, ESAT6:Fcγ1 protein dimerizes and bind to FcγRs, therefore, Fc-tagged protein could target APCs for inducing appropriate immune response or using in interferon-based assays. PMID:26778208

  3. Construction of Mycobacterium tuberculosis ESAT-6 fused to human Fcγ of IgG1: To target FcγR as a delivery system for enhancement of immunogenicity.

    PubMed

    Soleimanpour, Saman; Mohammadi, Mohammad Ali; Ghazvini, Kiarash; Jamehdar, Saeid Amel; Sadeghian, Hamid; Taghiabadi, Mahboubeh; Rezaee, S A R

    2016-04-15

    In order to prevent spreading of Mycobacterium tuberculosis (Mtb), it is necessary to discover effective vaccines, fast and reliable diagnosis, and appropriate treatment schemes. In the present study, an Fc-tagged recombinant Mtb-ESAT-6 was produced to make a selective delivery system for promoting cellular immunity. To determine 3D structure of the recombinant protein, model building was performed in MODELLER9v13 program. After preparation of Mtb-DNA and Fcγ1 cDNA, they were amplified by specific primers to make ESAT-6 and Fcγ1 products to fuse them in frame using splicing by overlap extension (SOEing)-PCR. After TA cloning, the construct was sequenced to confirm no errors have been introduced. The recombinant DNA was then subcloned into PDR2EF1α eukaryotic expression vector. The plasmid sequenced over the sites at which two DNA fragments were cloned to ensure that the ligation had generated an in-frame fusion of the genes. The CHO cells were then stably transected by PDR2EF1α-ESAT-6:Fcγ1 vector using lipofectamin and the expression and its binding to the Fcγ receptor (FcγRI) on APCs were confirmed by immunofluorescence assay (IFA). The IFA results demonstrated that ESAT6:Fcγ1 was expressed in engineered CHO cells. Semi-scale protein production and purification using HiTrap-PA column showed a high secretion of the recombinant protein by Western blotting method. The molecular weight of the monomer in the SDS-PAGE was equal to a protein of 50kDa, which dimerizes by disulfide bond of Fcγ fragments. Since, ESAT6:Fcγ1 protein dimerizes and bind to FcγRs, therefore, Fc-tagged protein could target APCs for inducing appropriate immune response or using in interferon-based assays.

  4. Host-pathogen interactions: leukocyte phagocytosis and associated sequelae.

    PubMed

    Voyich, Jovanka M; DeLeo, Frank R

    2002-01-01

    Polymorphonuclear leukocytes (PMNs) are a critical component of the human innate immune response and are the first line of defense against invading microorganisms. Phagocytosis of invading microbes induces production of reactive oxygen species (ROS) by PMNs, which facilitates bactericidal activity. In addition to eliminating microorganisms, phagocytosis also accelerates PMN apoptosis, a process critical for resolution of inflammation. Inasmuch as leukocyte phagocytosis and ROS production are key components of the innate immune response, we developed flow cytometric methods to evaluate these processes in human PMNs. In contrast to traditional microscopy-based analyses, the methods described herein provide objective and high throughput measures of host cell-pathogen interactions. Importantly, they can be adapted for use with a number of fluorometric probes, and bacterium and host cell of choice, and each is based upon a common phagocytosis assay system. We also describe methods to measure phagocytosis-induced PMN apoptosis with this assay system. These methods entail detecting surface-exposed phosphatidylserine (early apoptosis), and measuring PMN chromatin condensation and DNA fragmentation (late apoptosis). Taken together, these assays provide rapid and accurate assessment of critical PMN processes. PMID:12815296

  5. Neutrophil adhesion in leukocyte adhesion deficiency syndrome type 2.

    PubMed Central

    Phillips, M L; Schwartz, B R; Etzioni, A; Bayer, R; Ochs, H D; Paulson, J C; Harlan, J M

    1995-01-01

    We have previously reported a newly discovered congenital disorder of neutrophil adhesion, leukocyte adhesion deficiency syndrome type 2 (LAD II). The clinical manifestations of this syndrome are similar to those seen in the classic leukocyte adhesion deficiency syndrome, now designated type 1 (LAD I), but the two syndromes differ in the molecular basis of their adhesion defects. LAD I is caused by a deficiency in the CD18 integrin adhesion molecules while LAD II patients are deficient in expression of sialyl-Lewis X (SLeX), a carbohydrate ligand for selectins. In this report we demonstrate that neutrophils from a LAD II patient bind minimally or not at all to recombinant E-selectin, purified platelet P-selectin, or P-selectin expressed on histamine-activated human umbilical vein endothelial cells, but have normal levels of L-selectin and CD11b/CD18 integrin, and adhere to and migrate across endothelium when CD11b/CD18 is activated. We compare LAD I and LAD II patient neutrophil function in vitro, demonstrating that integrin and selectin adhesion molecules have distinct but interdependent roles in neutrophil adhesion during an inflammatory response. Images PMID:8675661

  6. Leukocyte responses to immobilized patterns of CXCL8.

    PubMed

    Girrbach, Maria; Rink, Ina; Ladnorg, Tatjana; Azucena, Carlos; Heißler, Stefan; Haraszti, Tamás; Schepers, Ute; Schmitz, Katja

    2016-06-01

    The attachment of neutrophils to the endothelial surface and their migration towards the site of inflammation following chemokine gradients play an essential role in the innate immune response. Chemokines adhere to glycosaminoglycans on the endothelial surface to be detected by leukocytes and trigger their movement along surface- bound gradients in a process called haptotaxis. In assays to systematically study the response of leukocytes to surface-bound compounds both the spatial arrangement of the compound as well as the mode of immobilization need to be controlled. In this study microcontact printing was employed to create patterns of hydrophobic or functionalized thiols on gold-coated glass slides and CXCL8 was immobilized on the thiol coated areas using three different strategies. Human neutrophils adhered to the CXCL8-coated lines but not to the PEG-coated background. We could show that more cells adhered to CXCL8 adsorbed to hydrophobic octadecanethiol than on CXCL8 covalently bound to amino undecanethiol or CXCL8 specifically bound to immobilized heparin on aminothiol. Likewise general cell activity such as lamellipodia formation and random migration were most pronounced for CXCL8 adsorbed on a hydrophobic surface which may be attributed to the larger amounts of protein immobilized on this type of surface. PMID:26970827

  7. Intranuclear crystalloids associated with abnormal granules in eosinophilic leukocytes.

    PubMed

    Parmley, R T; Crist, W M; Roper, M; Takagi, M; Austin, R L

    1981-12-01

    Ultrastructural evaluation of eosinophilic leukocytes from a 2-yr-old asymptomatic girl with chronic benign neutropenia (CBN) revealed a variety of morphological abnormalities. All eosinophils obtained from blood and marrow specimens contained multipole microcrystalloids in most of the mature cytoplasmic granules. An increase in crystalloid-free, immature granules in late (bilobed nuclei) eosinophils suggested a delay in granule maturation. The eosinophil granules appeared to be of normal size and demonstrated normal acid phosphatase reactivity. Eosinophilic myelocytes contained abnormal cisternae of rough endoplasmic reticulum (RER) and lacked abundant elongated RER cisternae seen in normal cells. A few eosinophilic myelocytes in specimens of bone marrow from the child contained large intranuclear crystalloids measuring up to 3 mu in length. The intranuclear crystalloid contained as cubic lattice of dense material with a periodicity similar to that described for cytoplasmic crystalloids. The ultrastructural morphology of marrow neutrophils was normal, as described in other cases of CBN. Ultrastructural examination of blood eosinophils from the father demonstrated microcrystalloids in cytoplasmic granules identical to those seen in the child. The father was asymptomatic and had normal leukocyte counts. Thus, anomalous crystalloid granule genesis occurred in the father and daughter and was not necessarily associated with neutropenia or clinical symptomatology. This anomaly is associated with the accumulation of intranuclear crystalloid material in eosinophilic myelocytes, which do not appear to be released from the marrow compartment. PMID:7306702

  8. The history of fever, leukocytic pyrogen and interleukin-1

    PubMed Central

    Dinarello, Charles A

    2015-01-01

    There has been great progress in the 30 y since the reporting in 1984 of the cDNA for interleukin1 (IL1) β in the human and IL1α in the mouse. However, the history of IL1 begins in the early 1940s with investigations into the nature of an endogenous fever-producing protein released rabbit peritoneal neutrophils. Most researchers in immunology today are unaware that the field of cytokines, particularly the field of inflammatory cytokines. Toll-like receptors and innate immunity traces back to studies on fever. Researchers in infectious diseases wanted to know about an endogenous protein that caused fever, independent of infection. The endogenous fever-producing protein was called by various names: granulocyte, endogenous or leukocytic pyrogen. It is a fascinating and sometimes controversial story for biology and medicine and for the treatment of inflammatory diseases. Few imagined that this fever-producing protein would play such a major role in nearly every cell and in most diseases. This paper reviews the true background and milestones of interleukin1 from the purification of leukocytic pyrogen to the first cDNA of IL1β and the validation of cytokine biology from ill-defined factors to its present day importance. PMID:27226996

  9. Modulation of leukocyte behavior by an inflamed extracellular matrix.

    PubMed

    Schor, H; Vaday, G G; Lider, O

    2000-01-01

    Inflammation is a response of the immune system to foreign insult or physical damage. Various cellular and humoral components of the immune system are recruited from the vascular system and are translocated through endothelium, and into extracellular matrix (ECM) compartments of inflamed tissues. This translocation is orchestrated by various types of accessory signals, in the form of soluble or complexed molecules, which evoke remarkable transitions in leukocyte activities. Recruited inflammatory cells give rise to mechanisms of migration, including the secretion of enzymes and other pro-inflammatory mediators and the alteration of their adhesive contacts with the ECM. Hence, migrating cells secrete enzymes, chemokines, and cytokines which interact with the ECM, and thereby, provide the cells with intrinsic signals for coordinating their responses. Resultant products of enzymatic modifications to the ECM microenvironment, such as cytokine- and ECM-derived molecules, may be also part of a cell-signaling mechanism that provides leukocytes with information about the nature of their inflammatory activity; such a mechanism may give the immune system data that can be cognitively interpreted for consequential activities. This article reviews the findings that support this notion and describe the dynamic interactions between participants of the inflammatory processes. PMID:11097214

  10. Inactivation of α2-Macroglobulin by Activated Human Polymorphonuclear Leukocytes

    PubMed Central

    Croisier, J.-L.; Camus, G.; Brumioul, D.; Mathy-Hartert, M.; Sondag, D.; Deby, C.; Lamy, M.

    1994-01-01

    The proteolytic activity of trypsin releases the dye Remazol Brilliant Blue from its high molecular weight substrate, the skin powder (Hide Powder Azure, Sigma), with an increase in absorbance at 595 nm. Active α2- macroglobulin (80 μg/ml) totally inhibits the proteolytic activity of trypsin (14 μg/ml) by trapping this protease. But after a 20 min incubation of α2-macroglobulin at 37°C with 2 × 106 human polymorphonuclear leukocytes activated by N-formyl-L-methionyl-L-leucyl-L-phenylalanine (10−7 M) and cytochalasin B (10−8 M), 100% of trypsin activity was recovered, indicating a total inactivation of α2-macroglobuHn. Incubation with granulocyte myeloperoxidase also inactivates α2-macroglobulin. Hypochlorous acid, a by-product of myeloperoxidase activity, at a concentration of 10−7 M also inactivates α2-macroglobulin, which indicates that an important cause of α2-macroglobulin inactivation by activated polymorphonuclear leukocytes could be the activity of myeloperoxidase. PMID:18472929

  11. Intranuclear crystalloids associated with abnormal granules in eosinophilic leukocytes

    SciTech Connect

    Parmley, R.T.; Crist, W.M.; Roper, M.; Takagi, M.; Austin, R.L.

    1981-12-01

    Ultrastructural evaluation of eosinophilic leukocytes from a 2-yr-old asymptomatic girl with chronic benign neutropenia (CBN) revealed a variety of morphological abnormalities. All eosinophils obtained from blood and marrow specimens contained multiple microcrystalloids in most of the mature cytoplasmic granules. An increase in crystalloid-free, immature granules in late (bilobed nuclei) eosinophils suggested a delay in granule maturation. The eosinophil granules appeared to be of normal size and demonstrated normal acid phosphatase reactivity. Eosinophilic myelocytes contained abnormal cisternae of rough endoplasmic reticulum (RER) and lacked abundant elongated RER cisternae seen in normal cells. A few eosinophilic myelocytes in specimens of bone marrow from the child contained large intranuclear crystalloids measuring up to 3 mu in length. The intranuclear crystalloid contained as cubic lattice of dense material with a periodicity similar to that described for cytoplasmic crystalloids. The ultrastructural morphology of marrow neutrophils was normal, as described in other cases of CBN. Ultrastructural examination of blood eosinophils from the father demonstrated microcrystalloids in cytoplasmic granules identical to those seen in the child. The father was asymptomatic and had normal leukocyte counts. Thus, anomalous crystalloid granule genesis occurred in the father and daughter and was not necessarily associated with neutropenia or clinical symptomatology. This anomaly is associated with the accumulation of intranuclear crystalloid material in eosinophilic myelocytes, which do not appear to be released from the marrow compartment.

  12. Electromagnetic wave emitting products and "Kikoh" potentiate human leukocyte functions.

    PubMed

    Niwa, Y; Iizawa, O; Ishimoto, K; Jiang, X; Kanoh, T

    1993-09-01

    Tourmaline (electric stone, a type of granite stone), common granite stone, ceramic disks, hot spring water and human palmar energy (called "Kikoh" in Japan and China), all which emit electromagnetic radiation in the far infrared region (wavelength 4-14 microns). These materials were thus examined for effects on human leukocyte activity and on lipid peroxidation of unsaturated fatty acids. It was revealed that these materials significantly increased intracellular calcium ion concentration, phagocytosis, and generation of reactive oxygen species in neutrophils, and the blastogenetic response of lymphocytes to mitogens. Chemotactic activity by neutrophils was also enhanced by exposure to tourmaline and the palm of "Kikohshi" i.e., a person who heals professionally by the laying on of hands. Despite the increase in reactive oxygen species generated by neutrophils, lipid peroxidation from unsaturated fatty acid was markedly inhibited by these four materials. The results suggest that materials emitting electromagnetic radiation in the far infrared range, which are widely used in Japan for cosmetic, therapeutic, and preservative purposes, appear capable of potentiating leukocyte functions without promoting oxidative injury. PMID:8406976

  13. Opsonic requirements for phagocytosis of Legionella micdadei by polymorphonuclear leukocytes.

    PubMed Central

    Steffensen, D O; Weinbaum, D L; Dowling, J N

    1985-01-01

    The roles of the classical and alternative pathways of complement activation and of antibody in the phagocytosis of Legionella micdadei by polymorphonuclear leukocytes were studied. Normal serum was treated with the appropriate chelators or with heat to inactivate the classical, alternate, or both pathways of complement activation. Normal and complement-depleted sera with or without antibody were employed as opsonins for L. micdadei in phagocytosis assays. There was no difference in the phagocytosis of L. micdadei promoted by normal serum and either C4-deficient serum or serum in which the classical pathway had been inactivated. Both normal and classical pathway-deficient sera promoted significantly greater phagocytosis than did sera in which the alternate pathway or both the alternate and classical pathways had been inactivated. Thus, polymorphonuclear leukocyte phagocytosis of L. micdadei in the absence of antibody required an intact alternate pathway. Specific antibody partially restored opsonization to sera deficient in the alternate or both complement pathways, but phagocytosis was still significantly less than that with the alternate pathway intact. PMID:4030099

  14. Electromagnetic wave emitting products and "Kikoh" potentiate human leukocyte functions.

    PubMed

    Niwa, Y; Iizawa, O; Ishimoto, K; Jiang, X; Kanoh, T

    1993-09-01

    Tourmaline (electric stone, a type of granite stone), common granite stone, ceramic disks, hot spring water and human palmar energy (called "Kikoh" in Japan and China), all which emit electromagnetic radiation in the far infrared region (wavelength 4-14 microns). These materials were thus examined for effects on human leukocyte activity and on lipid peroxidation of unsaturated fatty acids. It was revealed that these materials significantly increased intracellular calcium ion concentration, phagocytosis, and generation of reactive oxygen species in neutrophils, and the blastogenetic response of lymphocytes to mitogens. Chemotactic activity by neutrophils was also enhanced by exposure to tourmaline and the palm of "Kikohshi" i.e., a person who heals professionally by the laying on of hands. Despite the increase in reactive oxygen species generated by neutrophils, lipid peroxidation from unsaturated fatty acid was markedly inhibited by these four materials. The results suggest that materials emitting electromagnetic radiation in the far infrared range, which are widely used in Japan for cosmetic, therapeutic, and preservative purposes, appear capable of potentiating leukocyte functions without promoting oxidative injury.

  15. Leukocyte subsets and neutrophil function after short-term spaceflight

    NASA Technical Reports Server (NTRS)

    Stowe, R. P.; Sams, C. F.; Mehta, S. K.; Kaur, I.; Jones, M. L.; Feeback, D. L.; Pierson, D. L.

    1999-01-01

    Changes in leukocyte subpopulations and function after spaceflight have been observed but the mechanisms underlying these changes are not well defined. This study investigated the effects of short-term spaceflight (8-15 days) on circulating leukocyte subsets, stress hormones, immunoglobulin levels, and neutrophil function. At landing, a 1.5-fold increase in neutrophils was observed compared with preflight values; lymphocytes were slightly decreased, whereas the results were variable for monocytes. No significant changes were observed in plasma levels of immunoglobulins, cortisol, or adrenocorticotropic hormone. In contrast, urinary epinephrine, norepinephrine, and cortisol were significantly elevated at landing. Band neutrophils were observed in 9 of 16 astronauts. Neutrophil chemotactic assays showed a 10-fold decrease in the optimal dose response after landing. Neutrophil adhesion to endothelial cells was increased both before and after spaceflight. At landing, the expression of MAC-1 was significantly decreased while L-selectin was significantly increased. These functional alterations may be of clinical significance on long-duration space missions.