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. 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.

  3. Characterization of the human platelet Fc sub. gamma. receptor

    SciTech Connect

    King, M.

    1988-01-01

    Thrombocytopenia is often associated with immune complex disease and may in part be due to the interaction of circulating (IgG) immune complexes with an Fc{sub {gamma}} receptor on the platelet surface. Characterization of the immune complex-platelet interaction should provide for a better understanding of the pathophysiology of immune thrombocytpenia. To this end, a ligand binding assay, employing {sup 125}I-IgG trimer, was established. Receptor expression was determined by measuring the saturable binding of radiolabeled trimer to platelets at equilibrium. Normal human platelets were observed to express 8559 {plus minus} 852 binding sites for IgG trimer with a Kd of 12.5 {plus minus} 1.7 {times} 10{sup {minus}8} M. Binding of IgG trimer to human platelets was blocked following preincubation of the cells with an anti-Fc{sub {gamma}}RII monoclonal antibody. Furthermore, this binding was ionic-strength dependent but was unaffected by the presence of Mg{sup ++} or cytochalasin B. Platelet Fc{sub {gamma}} receptor modulation was examined by assessing the effects of various physiologic and pharmacologic on the ability of platelets to bind IgG trimer. Platelet Fc{sub {gamma}} receptor expression was not affected by thrombin, ADP, or {gamma}-interferon. However, in 7/12 normal donors, treatment of platelets with dexamethasone resulted in a decrease in the number of Fc{sub {gamma}} receptors expressed.

  4. Defect in the membrane expression of high affinity 72-kD Fc gamma receptors on phagocytic cells in four healthy subjects.

    PubMed Central

    Ceuppens, J L; Baroja, M L; Van Vaeck, F; Anderson, C L

    1988-01-01

    Three different receptors for the Fc portion of IgG (FcR) have been characterized on human leukocytes. We have identified four healthy members of one family, whose blood phagocytic cells lack functional 72 kD high-affinity FcRI. Their monocytes were unable to bind the Fc portion of mouse (m)-IgG2a and of monomeric human IgG, and they were unreactive with two anti-FcRI monoclonal antibodies. Thus, FcRI is either absent, expressed at very low density, or is so structurally altered as to be unable to bind both its ligand and the anti-FcRI antibodies. The failure to bind the Fc portion of mIgG2a underlies the previously reported inability of these monocytes to support T cell mitogenesis on OKT3 stimulation. FcRI was not inducible upon incubation of their monocytes or neutrophils in gamma interferon. However, their monocytes were able to bind aggregated human IgG, and to phagocytose IgG-coated particles in vitro. Both functions could be blocked with a monoclonal antibody to the 40-kD low-affinity FcRII and therefore apparently were mediated exclusively through FcRII. This also demonstrates that FcRII can mediate phagocytosis independently. Despite the FcRI defect, these subjects had no circulating immune complexes, no evidence of autoimmune pathology and no increased susceptibility to infections. PMID:2969920

  5. 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

  6. Fc Gamma Receptor IIIB (FcγRIIIB) Polymorphisms Are Associated with Clinical Malaria in Ghanaian Children

    PubMed Central

    Adu, Bright; Dodoo, Daniel; Adukpo, Selorme; Hedley, Paula L.; Arthur, Fareed K. N.; Gerds, Thomas A.; Larsen, Severin O.; Christiansen, Michael; Theisen, Michael

    2012-01-01

    Plasmodium falciparum malaria kills nearly a million people annually. Over 90% of these deaths occur in children under five years of age in sub-Saharan Africa. A neutrophil mediated mechanism, the antibody dependent respiratory burst (ADRB), was recently shown to correlate with protection from clinical malaria. Human neutrophils constitutively express Fc gamma receptor-FcγRIIA and FcγRIIIB by which they interact with immunoglobulin (Ig) G (IgG)-subclass antibodies. Polymorphisms in exon 4 of FCGR2A and exon 3 of FCGR3B genes encoding FcγRIIA and FcγRIIIB respectively have been described to alter the affinities of both receptors for IgG. Here, associations between specific polymorphisms, encoding FcγRIIA p.H166R and FcγRIIIB-NA1/NA2/SH variants with clinical malaria were investigated in a longitudinal malaria cohort study. FcγRIIA-p.166H/R was genotyped by gene specific polymerase chain reaction followed by allele specific restriction enzyme digestion. FCGR3B-exon 3 was sequenced in 585 children, aged 1 to 12 years living in a malaria endemic region of Ghana. Multivariate logistic regression analysis found no association between FcγRIIA-166H/R polymorphism and clinical malaria. The A-allele of FCGR3B-c.233C>A (rs5030738) was significantly associated with protection from clinical malaria under two out of three genetic models (additive: p = 0.0061; recessive: p = 0.097; dominant: p = 0.0076) of inheritance. The FcγRIIIB-SH allotype (CTGAAA) containing the 233A-allele (in bold) was associated with protection from malaria (p = 0.049). The FcγRIIIB-NA2*03 allotype (CTGCGA), a variant of the classical FcγRIIIB-NA2 (CTGCAA) was associated with susceptibility to clinical malaria (p = 0.0092). The present study is the first to report an association between a variant of FcγRIIIB-NA2 and susceptibility to clinical malaria and provides justification for further functional characterization of variants of the classical FcγRIIIB allotypes. This

  7. An Fc gamma RII-, Fc gamma RIII-specific monoclonal antibody (2.4G2) decreases acute Trypanosoma cruzi infection in mice.

    PubMed Central

    Araujo-Jorge, T; Rivera, M T; el Bouhdidi, A; Daëron, M; Carlier, Y

    1993-01-01

    In order to study the role of Fc gamma Rs in Trypanosoma cruzi infection in mice, the 2.4G2 monoclonal antibody (MAb), specific to the extracellular domains of Fc gamma RII and Fc gamma RIII, was injected intraperitoneally into mice. Flow cytometry studies of uninfected mice showed that 2.4G2 MAb bound to peritoneal and lymph node cells, respectively, on days 2 and 6 after injection. Repeating 2.4G2 injections every 3 to 4 days decreased the availability of Fc gamma Rs on peritoneal, lymph node, and spleen cells. Injections of 2.4G2 MAb into T. cruzi-infected mice, at days -1, 3, 7, 11, 16, 20, and 24 relative to infection, reduced mortality in comparison with that in infected animals injected with an unrelated MAb (50 versus 93.3% mortality; P < 0.01). Parasitemia in 2.4G2-treated mice was significantly (three times) lower than in control animals on days 21 and 24 postinfection (P < 0.05), before parasite-specific antibodies were detectable at significant levels. Immunoglobulin and T. cruzi-specific antibody levels were similar in all groups of mice. These results indicate that repeated injections of 2.4G2 MAb administered to acutely infected mice reduce the in vivo infection level, suggesting that Fc gamma Rs play a role in the early host invasion by T. cruzi parasites. Images PMID:8406898

  8. Fc gamma receptor IIa (CD32) polymorphism in fulminant meningococcal septic shock in children.

    PubMed

    Bredius, R G; Derkx, B H; Fijen, C A; de Wit, T P; de Haas, M; Weening, R S; van de Winkel, J G; Out, T A

    1994-10-01

    Antibodies are essential in host defense against Neisseria meningitidis. Therefore, interactions among IgG and Fc receptors (Fc gamma R) on phagocytes may be crucial. Genetic polymorphic forms of Fc gamma RIIa (CD32) express different functional activities. In a retrospective study, Fc gamma R polymorphisms were determined in 25 children who survived fulminant meningococcal septic shock: 11 had Fc gamma RIIa-R/R131, the poor IgG2-binding allotype, which is a significantly more frequent rate than found in a healthy white population (44% vs. 23%; P = .028; odds ratio = 2.67; 95% confidence interval, 1.09-6.53). The relevance of this finding was further supported by the fact that neutrophils with the Fc gamma RIIa-R/R131 allotype phagocytized N. meningitidis opsonized with polyclonal IgG2 antibodies less effectively than did IIa-H/H131 neutrophils. Our findings suggest an important role for anti-N. meningitidis IgG2 and the Fc gamma RIIa polymorphism in host defense against systemic meningococcal infections. PMID:7930726

  9. 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.

  10. Protein tyrosine kinase activity is essential for Fc gamma receptor-mediated intracellular killing of Staphylococcus aureus by human monocytes.

    PubMed Central

    Zheng, L; Nibbering, P H; Zomerdijk, T P; van Furth, R

    1994-01-01

    Our previous study revealed that the intracellular killing of Staphylococcus aureus by human monocytes after cross-linking Fc gamma receptor I (Fc gamma RI) or Fc gamma RII is a phospholipase C (PLC)-dependent process. The aim of the present study was to investigate whether protein tyrosine kinase (PTK) activity plays a role in the Fc gamma R-mediated intracellular killing of bacteria and activation of PLC in these cells. The results showed that phagocytosis of bacteria by monocytes was not affected by the PTK inhibitors genistein and tyrphostin-47. The intracellular killing of S. aureus by monocytes after cross-linking Fc gamma RII or Fc gamma RII with anti-Fc gamma R monoclonal antibody and a bridging antibody or with human immunoglobulin G (IgG) was inhibited by these compounds in a dose-dependent fashion. The production of O2- by monocytes after stimulation with IgG or IgG-opsonized S. aureus was almost completely blocked by the PTK inhibitor. These results indicate that inhibition of PTK impairs the oxygen-dependent bactericidal mechanisms of monocytes. Genistein and tyrphostin-47, which do not affect the enzymatic activity of purified PLC, prevented activation of PLC after cross-linking Fc gamma RI or Fc gamma RII, measured as an increase in the intracellular inositol 1,4,5-trisphosphate concentration. Cross-linking Fc gamma RI or Fc gamma RII induced rapid tyrosine phosphorylation of several proteins in monocytes, one of which was identified as PLC-gamma 1, and the phosphorylation could be completely blocked by PTK inhibitors, leading to the conclusion that activation of PLC after cross-linking Fc gamma R in monocytes is regulated by PTK activity. Together, these results demonstrate that PTK activity is essential for the activation of PLC which is involved in the Fc gamma R-mediated intracellular killing of S. aureus by human monocytes. Images PMID:7927687

  11. 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

  12. Fc receptors for IgG (Fc gamma Rs) on human monocytes and macrophages are not infectivity receptors for human immunodeficiency virus type 1 (HIV-1): studies using bispecific antibodies to target HIV-1 to various myeloid cell surface molecules, including the Fc gamma R.

    PubMed Central

    Connor, R I; Dinces, N B; Howell, A L; Romet-Lemonne, J L; Pasquali, J L; Fanger, M W

    1991-01-01

    Fc gamma Rs (Fc gamma RI, Fc gamma RII, and Fc gamma RIII) are highly expressed on human mononuclear phagocytes and function in the clearance of immune complexes and opsonized pathogens. We have examined the role of Fc gamma R in mediating antibody-dependent clearance of HIV-1 by human monocytes and monocyte-derived macrophages by using bispecific antibodies (BsAbs) to independently target the virus to Fc gamma RI, Fc gamma RII, or Fc gamma RIII. Virus production was markedly reduced in monocytes cultured with strain HIV-1IIIB opsonized with BsAbs that target the virus to either Fc gamma RI or Fc gamma RII compared to monocytes cultured with virus in the absence of BsAbs or in the presence of BsAbs that target the virus to non-Fc gamma R surface antigens (CD33 and HLA-A,B,C). These results were confirmed using the monotropic isolate HIV-1JRFL. Interaction of HIV-1JRFL with Fc gamma RI or Fc gamma RII on human monocytes and Fc gamma RI, Fc gamma RII, or Fc gamma RIII on monocyte-derived macrophages resulted in markedly reduced levels of virus production in these cultures. Moreover, HIV-1 infection of monocytes and monocyte-derived macrophages was completely blocked by anti-CD4 monoclonal antibodies, indicating that interaction with CD4 is required for infectivity even under conditions of antibody-mediated binding of HIV-1 to Fc gamma R. Thus, we propose that highly opsonized HIV-1 initiates high-affinity multivalent interactions with Fc gamma R that trigger endocytosis and intracellular degradation of the antibody-virus complex. At lower levels of antibody opsonization, there are two few interactions with Fc gamma R to initiate endocytosis and intracellular degradation of the antibody-virus complex, but there are enough interactions to stabilize the virus at the cell surface, allowing antibody-dependent enhancement of HIV-1 infection through high-affinity CD4 interactions. However, our results suggest that interaction of highly opsonized HIV-1 with Fc gamma Rs

  13. Control of Cytokine Production by Human Fc Gamma Receptors: Implications for Pathogen Defense and Autoimmunity

    PubMed Central

    Vogelpoel, Lisa T. C.; Baeten, Dominique L. P.; de Jong, Esther C.; den Dunnen, Jeroen

    2015-01-01

    Control of cytokine production by immune cells is pivotal for counteracting infections via orchestration of local and systemic inflammation. Although their contribution has long been underexposed, it has recently become clear that human Fc gamma receptors (FcγRs), which are receptors for the Fc region of immunoglobulin G (IgG) antibodies, play a critical role in this process by controlling tissue- and pathogen-specific cytokine production. Whereas individual stimulation of FcγRs does not evoke cytokine production, FcγRs cell-type specifically interact with various other receptors for selective amplification or inhibition of particular cytokines, thereby tailoring cytokine responses to the immunological context. The physiological function of FcγR-mediated control of cytokine production is to counteract infections with various classes of pathogens. Upon IgG opsonization, pathogens are simultaneously recognized by FcγRs as well as by various pathogen-sensing receptors, leading to the induction of pathogen class-specific immune responses. However, when erroneously activated, the same mechanism also contributes to the development of autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. In this review, we discuss control of cytokine production as a novel function of FcγRs in human innate immune cells in the context of homeostasis, infection, and autoimmunity and address the possibilities for future therapeutic exploitation. PMID:25759693

  14. 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

  15. Expression Profile of FcγRIIb on Leukocytes and Its Dysregulation in Systemic Lupus Erythematosus1

    PubMed Central

    Su, Kaihong; Yang, Hengxuan; Li, Xinrui; Li, Xiaoli; Gibson, Andrew W.; Cafardi, John M.; Zhou, Tong; Edberg, Jeffrey C.; Kimberly, Robert P.

    2010-01-01

    FcγRIIb (CD32B, Online Mendelian Inheritance in Man 604590), an IgG FcR with a tyrosine-based inhibitory motif, plays a critical role in the balance of tolerance and autoimmunity in murine models. However, the high degree of homology between FcγRIIb and FcγRIIa in humans and the lack of specific Abs to differentiate them have hampered study of the normal expression profile of FcγRIIb and its potential dysregulation in autoimmune diseases such as systemic lupus erythematosus (SLE). Using our newly developed anti-FcγRIIb mAb 4F5 which does not react with FcγRIIa, we found that FcγRIIb is expressed on the cell surface of circulating B lymphocytes, monocytes, neutrophils, myeloid dendritic cells (DCs), and at very low levels on plasmacytoid DCs from some donors. Normal donors with the less frequent 2B.4 promoter haplotype have higher FcγRIIb expression on monocytes, neutrophils, and myeloid DCs similar to that reported for B lymphocytes, indicating that FcγRIIb expression on both myeloid and lymphoid cells is regulated by the naturally occurring regulatory single nucleotide polymorphisms in the FCGR2B promoter. FcγRIIb expression in normal controls is up-regulated on memory B lymphocytes compared with naive B lymphocytes. In contrast, in active SLE, FcγRIIb is significantly down-regulated on both memory and plasma B lymphocytes compared with naive and memory/plasma B lymphocytes from normals. Similar down-regulation of FcγRIIb on myeloid-lineage cells in SLE was not seen. Our studies demonstrate the constitutive regulation of FcγRIIb by natural gene polymorphisms and the acquired dysregulation in SLE autoimmunity, which may identify opportunities for using this receptor as a therapeutic target. PMID:17312177

  16. 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.

  17. 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.

  18. Evaluation of High-Throughput Genomic Assays for the Fc Gamma Receptor Locus.

    PubMed

    Hargreaves, Chantal E; Iriyama, Chisako; Rose-Zerilli, Matthew J J; Nagelkerke, Sietse Q; Hussain, Khiyam; Ganderton, Rosalind; Lee, Charlotte; Machado, Lee R; Hollox, Edward J; Parker, Helen; Latham, Kate V; Kuijpers, Taco W; Potter, Kathleen N; Coupland, Sarah E; Davies, Andrew; Stackpole, Michael; Oates, Melanie; Pettitt, Andrew R; Glennie, Martin J; Cragg, Mark S; Strefford, Jonathan C

    2015-01-01

    Cancer immunotherapy has been revolutionised by the use monoclonal antibodies (mAb) that function through their interaction with Fc gamma receptors (FcγRs). The low-affinity FcγR genes are highly homologous, map to a complex locus at 1p23 and harbour single nucleotide polymorphisms (SNPs) and copy number variation (CNV) that can impact on receptor function and response to therapeutic mAbs. This complexity can hinder accurate characterisation of the locus. We therefore evaluated and optimised a suite of assays for the genomic analysis of the FcγR locus amenable to peripheral blood mononuclear cells and formalin-fixed paraffin-embedded (FFPE) material that can be employed in a high-throughput manner. Assessment of TaqMan genotyping for FCGR2A-131H/R, FCGR3A-158F/V and FCGR2B-232I/T SNPs demonstrated the need for additional methods to discriminate genotypes for the FCGR3A-158F/V and FCGR2B-232I/T SNPs due to sequence homology and CNV in the region. A multiplex ligation-dependent probe amplification assay provided high quality SNP and CNV data in PBMC cases, but there was greater data variability in FFPE material in a manner that was predicted by the BIOMED-2 multiplex PCR protocol. In conclusion, we have evaluated a suite of assays for the genomic analysis of the FcγR locus that are scalable for application in large clinical trials of mAb therapy. These assays will ultimately help establish the importance of FcγR genetics in predicting response to antibody therapeutics. PMID:26545243

  19. Evaluation of High-Throughput Genomic Assays for the Fc Gamma Receptor Locus

    PubMed Central

    Hargreaves, Chantal E.; Iriyama, Chisako; Rose-Zerilli, Matthew J. J.; Nagelkerke, Sietse Q.; Hussain, Khiyam; Ganderton, Rosalind; Lee, Charlotte; Machado, Lee R.; Hollox, Edward J.; Parker, Helen; Latham, Kate V.; Kuijpers, Taco W.; Potter, Kathleen N.; Coupland, Sarah E.; Davies, Andrew; Stackpole, Michael; Oates, Melanie; Pettitt, Andrew R.; Glennie, Martin J.; Cragg, Mark S.; Strefford, Jonathan C.

    2015-01-01

    Cancer immunotherapy has been revolutionised by the use monoclonal antibodies (mAb) that function through their interaction with Fc gamma receptors (FcγRs). The low-affinity FcγR genes are highly homologous, map to a complex locus at 1p23 and harbour single nucleotide polymorphisms (SNPs) and copy number variation (CNV) that can impact on receptor function and response to therapeutic mAbs. This complexity can hinder accurate characterisation of the locus. We therefore evaluated and optimised a suite of assays for the genomic analysis of the FcγR locus amenable to peripheral blood mononuclear cells and formalin-fixed paraffin-embedded (FFPE) material that can be employed in a high-throughput manner. Assessment of TaqMan genotyping for FCGR2A-131H/R, FCGR3A-158F/V and FCGR2B-232I/T SNPs demonstrated the need for additional methods to discriminate genotypes for the FCGR3A-158F/V and FCGR2B-232I/T SNPs due to sequence homology and CNV in the region. A multiplex ligation-dependent probe amplification assay provided high quality SNP and CNV data in PBMC cases, but there was greater data variability in FFPE material in a manner that was predicted by the BIOMED-2 multiplex PCR protocol. In conclusion, we have evaluated a suite of assays for the genomic analysis of the FcγR locus that are scalable for application in large clinical trials of mAb therapy. These assays will ultimately help establish the importance of FcγR genetics in predicting response to antibody therapeutics. PMID:26545243

  20. Expression of Fc gamma and complement receptors in monocytes of X-linked agammaglobulinaemia and common variable immunodeficiency patients.

    PubMed

    Amoras, A L B; da Silva, M T N; Zollner, R L; Kanegane, H; Miyawaki, T; Vilela, M M S

    2007-12-01

    Recently we reported that monocyte phagocytosis and chemotaxis are impaired in X-linked agammaglobulinaemia (XLA) and common variable immunodeficiency (CVI) patients. Few data exist on the in vivo expression of receptors for the constant region of immunoglobulin (IgG) (Fc gammaR) and complement receptors (CR) in these patients. The objective of this study was to investigate the expression of Fc gammaR and CR on monocytes from XLA and CVI patients and compare it to that of healthy controls. Whole blood samples were obtained from 10 patients with XLA, 12 with CVI and 18 healthy controls. Monocyte phenotype was determined by flow cytometry with gating on CD14+ cells. Surface expression of Fc gammaRI (CD64), Fc gammaRII (CD32) and Fc gammaRIII (CD16), CR1 (CD35) and CR3 (CD11b and CD18) was measured by determination of the proportion of CD14+ cells positive for each receptor and by receptor density. Compared to controls, a significantly higher percentage of CD16 and CD35+ monocytes from XLA (P = 0.002 and P = 0.007, respectively) were observed. The relative fluorescence intensity (RFI) expression of Fc gammaRII (CD32) and Fc gammaRIII (CD16) were significantly lower on CVI monocytes compared to controls (P = 0.001 and P = 0.035, respectively). XLA patients, who have a reduction of Bruton's tyrosine kinase (Btk), showed normal or increased percentages of monocytes expressing Fc gamma and complement receptors. CVI patients, who have normal expression of Btk, showed reduced expression of CD16 and CD32 on monocytes. Inefficient chemotaxis and phagocytosis, reported previously in XLA patients, could be due to defects of cytoplasmatic transduction mechanisms. PMID:17900300

  1. Biochemical signal transmitted by Fc gamma receptors: phospholipase A2 activity of Fc gamma 2b receptor of murine macrophage cell line P388D1.

    PubMed Central

    Suzuki, T; Saito-Taki, T; Sadasivan, R; Nitta, T

    1982-01-01

    The detergent lysate of the P388D1 macrophage cell line was subjected to affinity chromatography on two different media, Sepharose coupled to heat-aggregated human IgG (IgG-Sepharose) and Sepharose coupled to the phosphatidylcholine analog rac-1-(9-carboxyl)nonyl-2-hexadecylglycero-3-phosphocholine (PC-Sepharose). Both IgG- and phosphatidylcholine-binding proteins were further purified by Sephadex G-100 gel filtration and isoelectric focusing in the presence of 6 M urea. The isolated IgG-binding proteins specifically bound to IgG2a, but not to IgG2b, whereas the isolated phosphatidylcholine-binding proteins specifically bound to IgG2b but not to IgG2a. Phosphatidylcholine-binding proteins possessed a typical phospholipase A2 activity (phosphatide 2-acylhydrolase, EC 3.1.1.4), which was maximal (10 mumol/min per mg of protein) at pH 9.5, depended on Ca2+, and was specific for cleavage of fatty acid from the C-2 position of the glycerol backbone of phosphatidylcholine. The noted enzymatic activity was augmented 4-fold by preincubating phosphatidylcholine-binding proteins with heat-aggregated murine IgG2b but not with IgG2a. IgG-binding proteins, on the other hand, are devoid of any detectable phospholipase A2 activity. Thus, the functional significance of Fc gamma 2b receptor of P388D1 macrophage cell line would be the generation of phospholipase A2 activity at the cell surface upon specific binding to Fc gamma 2b fragment. PMID:6804944

  2. 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}.

  3. Human Fc(gamma) receptors for differentiation in throat cultures of group C "Streptococcus equisimilis" and group C "Streptococcus milleri".

    PubMed

    Lebrun, L; Guibert, M; Wallet, P; de Maneville, M M; Pillot, J

    1986-11-01

    The biochemical characteristics and the presence of human Fc(gamma) receptors of 52 throat isolates of group C beta-hemolytic streptococci were examined. Among these isolates, 38 were identified as "Streptococcus milleri" and 14 were identified as "Streptococcus equisimilis." The differentiation of group C "S. equisimilis" from "S. milleri" with identical group antigens was easy to perform by the measurement of the size of the hemolytic zone on a sheep blood agar plate in an anaerobic atmosphere and by biochemical tests (Voges-Proskauer test). A clear-cut criterion for differentiation was noted among these isolates, i.e., the presence of Fc(gamma) receptors. "S. equisimilis," which are generally associated with pharyngitis, possess human Fc(gamma) receptors, while "S. milleri", which are generally isolated from healthy persons, have no such receptors. PMID:3771760

  4. 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...

  5. Forced expression of the Fc receptor gamma-chain renders human T cells hyperresponsive to TCR/CD3 stimulation.

    PubMed

    Nambiar, Madhusoodana P; Fisher, Carolyn U; Kumar, Anil; Tsokos, Christos G; Warke, Vishal G; Tsokos, George C

    2003-03-15

    High level expression of Fc epsilon RI gamma chain replaces the deficient TCR zeta-chain and contributes to altered TCR/CD3-mediated signaling abnormalities in T cells of patients with systemic lupus erythematosus. Increased responsiveness to Ag has been considered to lead to autoimmunity. To test this concept, we studied early signaling events and IL-2 production in fresh cells transfected with a eukaryotic expression vector encoding the Fc epsilon RI gamma gene. We found that the overexpressed Fc epsilon RI gamma chain colocalizes with the CD3 epsilon chain on the surface membrane of T cells and that cross-linking of the new TCR/CD3 complex leads to a dramatic increase of intracytoplasmic calcium concentration, protein tyrosine phosphorylation, and IL-2 production. We observed that overexpression of Fc epsilon RI gamma is associated with increased phosphorylation of Syk kinase, while the endogenous TCR zeta-chain is down-regulated. We propose that altered composition of the CD3 complex leads to increased T cell responsiveness to TCR/CD3 stimulation and sets the biochemical grounds for the development of autoimmunity. PMID:12626537

  6. 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

  7. Involvement of protein kinase D in Fc gamma-receptor activation of the NADPH oxidase in neutrophils.

    PubMed Central

    Davidson-Moncada, Jan K; Lopez-Lluch, Guillermo; Segal, Anthony W; Dekker, Lodewijk V

    2002-01-01

    Protein kinases involved in the activation of the NADPH oxidase by Fc gamma receptors in neutrophils were studied. Of three different protein kinase C (PKC) inhibitors, Gö 6976 inhibited the NADPH oxidase completely, whereas bisindolylmaleimide I and Ro 31-8220 caused a 70-80% inhibition. Thus a Gö 6976-sensitive, bisindolylmaleimide I/Ro 31-8220-insensitive component contributes to NADPH oxidase activation induced by Fc gamma receptors. Down-regulation of PKC isotypes resulted in inhibition of Fc gamma-receptor-activated NADPH oxidase, but a down-regulation-insensitive component was still present. This component was sensitive to Gö 6976, but insensitive to Ro 31-8220. It has been shown previously that protein kinase D/PKC-mu (PKD) shows this same pharmacology in vitro. We show that PKD is present in neutrophils and that, in contrast with PKC isotypes, PKD is not down-regulated. Therefore PKD may participate in NADPH oxidase activation. To obtain direct evidence for this we adopted an antisense approach. Antisense PKD inhibited NADPH oxidase induced by Fc gamma-receptor stimulation by 50% and the Ro 31-8220-insensitive component in the activation was inhibited by antisense PKD. In vitro kinase assays showed that PKD is activated by presenting IgG-opsonized particles to neutrophils. Furthermore, PKD localizes to the area of particle intake in the cell and phosphorylates two of the three cytosolic components of the NADPH oxidase, p40(phox) and p47(phox). Taken together, these data indicate that Fc gamma receptors engage PKD in the regulation of the NADPH oxidase. PMID:11903052

  8. 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

  9. 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

  10. Apoptosis-promoted tumorigenesis: gamma-irradiation-induced thymic lymphomagenesis requires Puma-driven leukocyte death.

    PubMed

    Michalak, Ewa M; Vandenberg, Cassandra J; Delbridge, Alex R D; Wu, Li; Scott, Clare L; Adams, Jerry M; Strasser, Andreas

    2010-08-01

    Although tumor development requires impaired apoptosis, we describe a novel paradigm of apoptosis-dependent tumorigenesis. Because DNA damage triggers apoptosis through p53-mediated induction of BH3-only proteins Puma and Noxa, we explored their roles in gamma-radiation-induced thymic lymphomagenesis. Surprisingly, whereas Noxa loss accelerated it, Puma loss ablated tumorigenesis. Tumor suppression by Puma deficiency reflected its protection of leukocytes from gamma-irradiation-induced death, because their glucocorticoid-mediated decimation in Puma-deficient mice activated cycling of stem/progenitor cells and restored thymic lymphomagenesis. Our demonstration that cycles of cell attrition and repopulation by stem/progenitor cells can drive tumorigenesis has parallels in human cancers, such as therapy-induced malignancies. PMID:20679396

  11. [The changes of expression and Fc-gamma-receptor's polypeptide composition of fetal small intestine enterocytes in Bos primigenius taurus L].

    PubMed

    Masiuk, D M; Nedzvets'kyĭ, V S; Tsvilikhovs'kyĭ, M I; Nerush, P O

    2008-01-01

    The expression and polypeptide composition of Fc-gamma-receptors of enterocytes from Bos primigenius taurus L. intestine at 3-, 5-, 7-, 9- month of fetal development was investigated. The results of immunobloting show similar composition of Fc-gamma-receptors extracted from apical and basolateral membranes. The proteins that bind IgG after PAAG electrophoresis and transferring on nitrocellulose were observed as 120, 87, 72 and 43 kDa polypeptide line. The changes of each polypeptide contents were related to the changes of total content of Fc-gamma-receptor proteins. The rise in concentration of Fc-gamma-receptors on apical membrane was observed from 3-rd to 7-th month of fetal development. Maximal concentration of these proteins was detected on enterocytes at 7-th month of fetal development. Fc-gamma-receptors content on basolateral side was higher than on apical side. The presence of Fc-gamma-receptors on enterocyte's membrane indicates on active recycling of these receptors on plasma membrane and reflects early development of immune system in Bos primigenius taurus L. fetus. PMID:18416181

  12. 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.

  13. Involvement of the high-affinity receptor for IgG (Fc gamma RI; CD64) in enhanced tumor cell cytotoxicity of neutrophils during granulocyte colony-stimulating factor therapy.

    PubMed

    Valerius, T; Repp, R; de Wit, T P; Berthold, S; Platzer, E; Kalden, J R; Gramatzki, M; van de Winkel, J G

    1993-08-01

    Three different classes of Fc receptors for IgG (Fc gamma R) are currently distinguished in humans, of which polymorphonuclear phagocytes (PMN) normally express both low-affinity receptor classes--Fc gamma RII (CD32) and Fc gamma RIII (CD16). During therapy with granulocyte colony-stimulating factor (G-CSF), neutrophils from patients with various malignancies and different hematologic disorders were found to additionally express high levels of the receptor with high affinity for IgG (Fc gamma RI; CD64). For these patients, the relative fluorescence intensity (rFI) for Fc gamma RI was 5.3 (range, 1.7 to 10.3; n = 19), compared with 1.0 (range, 1.0 to 1.1; n = 8) for healthy donors. The expression of Fc gamma RI during G-CSF therapy could be confirmed by using a panel of six CD64-specific antibodies, and by showing mRNA for Fc gamma RI. So far, three genes for Fc gamma RI have been identified, encoding four distinct transcription products. By reverse transcriptase-polymerase chain reaction technology, transcripts for both membrane-associated isoforms (hFc gamma RIa and hFc gamma RIb2) could be detected. The functional activity of Fc gamma RI on PMN during G-CSF therapy was shown by measuring binding of monomeric human IgG and antibody-dependent cellular cytotoxicity (ADCC). Thus, Fc gamma RI-positive neutrophils displayed enhanced ADCC activity to glioma (A1207), squamous cell (A431), and ovarian (SK-ov3) carcinoma cell lines. The involvement of Fc gamma RI in this increased cytotoxic activity was shown by blocking Fc gamma receptors with monoclonal antibodies, and by using F(ab')2 x F(ab')2-bispecific antibodies with specificities against tumor-related antigens and Fc gamma RI, resulting in solely Fc gamma RI-mediated cytotoxicity. Therapeutically, this additional Fc receptor on PMN may increase the efficacy of experimental antibody therapy. PMID:7687898

  14. 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

  15. 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.

  16. 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

  17. Two cis-DNA elements involved in myeloid-cell-specific expression and gamma interferon (IFN-gamma) activation of the human high-affinity Fc gamma receptor gene: a novel IFN regulatory mechanism.

    PubMed Central

    Perez, C; Wietzerbin, J; Benech, P D

    1993-01-01

    The human high-affinity receptor for the constant region of immunoglobulin G (human Fc gamma R1) is encoded by two mRNAs induced selectively by gamma interferon (IFN-gamma) and expressed in cells of myeloid lineage. The cis-DNA element (GRR) previously found to confer IFN-gamma responsiveness to this gene acts as an inducible enhancer and is the target of an IFN-gamma-activated factor(s) (GIRE-BP) in cells of different origins. Although the GRR motif is not related to the DNA elements involved in the regulation of other IFN-stimulated genes, GIRE-BP binding depends on the IFN-gamma-dependent activation of the 91-kDa protein known to be one of the factors of a transcriptional complex activated by IFN-alpha. Deletions of the Fc gamma R1 promoter allowed us to identify a 25-bp element, downstream from the GRR motif, conferring cell-type-specific expression. This element, called MATE (myeloid activating transcription element), is the DNA target for constitutive factors forming two complexes, MATE-BP1 and MATE-BP2. In accordance with the functional analysis, MATE-BP binding activities were detected in extracts prepared from myeloid cell lines such as THP-1, HL-60, and U-937 but not in HeLa cell extracts. The MATE motif is present not only in the promoter of other Fc receptor genes but also in several promoters of genes whose expression is restricted to monocytic cells. Our results suggest that human Fc gamma R1 gene expression in myeloid cells is initiated by the interaction of IFN-gamma-activated factors with cell-type-specific factors through their binding to the GRR and MATE motifs. Images PMID:8455606

  18. Modulation of some Peyer's patch leukocyte functions following in vitro exposure to recombinant bovine alpha- and gamma-interferon.

    PubMed

    Nagi, A M; Babiuk, L A

    1988-09-01

    The immunomodulatory effects of recombinant bovine interferon-alpha 1(1) (rBoIFN-alpha 1(1] and -gamma (rBoIFN-gamma) on the response of bovine Peyer's patch leukocytes (PPL) to in vitro mitogenic stimulation were studied. The proliferative response of PPL to concanavalin A (Con A) and pokeweed mitogen (PWM) was significantly inhibited by the addition of 5-1000 units/ml of rBoIFN-alpha 1(1). In contrast, rBoIFN-gamma showed significant enhancement of 3H-Thymidine (3HTdR) incorporation of PPL cultures at concentrations of 5-500 units/ml. Although the results of this study substantiated the previously reported suppressive ability of IFN-alpha 1(1) and the stimulating capacity of IFN-gamma, suppression or enhancement of lymphocyte proliferation was shown to be dependent on the concentration of the polyclonal activator and the length of time the target cells were exposed to IFN. Pre-exposure of target cells to rBoIFN-alpha 1(1) significantly increased its suppressive activity against the PPL response to Con A stimulation. In contrast, pre-exposure of PPL to rBoIFN-gamma did not affect its stimulatory capacity. Prestimulation of target cells with Con A significantly decreased the stimulatory capacity of rBoIFN-gamma and the suppressive activity of rBoIFN-alpha 1(1). These data demonstrate qualitative differences in the effects of rBoIFN-alpha 1(1) compared to those of rBoIFN-gamma on immune cells other than commonly studied circulating leukocytes. PMID:3143664

  19. ANTIBODY-MEDIATED PROTECTION AGAINST GENITAL HERPES SIMPLEX VIRUS TYPE 2 DISEASE IN MICE BY FC GAMMA RECEPTOR -DEPENDENT AND -INDEPENDENT MECHANISMS

    PubMed Central

    Chu, Chin-Fun; Meador, Michael G.; Young, Christal G.; Strasser, Jane E.; Bourne, Nigel; Milligan, Gregg N.

    2008-01-01

    The ability of antibody (Ab) to modulate HSV pathogenesis is well recognized but the mechanisms by which HSV-specific IgG antibodies protect against genital HSV-2 disease are not well understood. The requirement for Ab interactions with Fcγ receptors (FcγR) in protection was examined using a murine model of genital HSV-2 infection. IgG antibodies isolated from the serum of HSV-immune mice protected normal mice against HSV-2 disease when administered prior to genital HSV-2 inoculation. However, protection was significantly diminished in recipient mice lacking the gamma chain subunit utilized in FcγRI, FcγRIII, FcγRIV and FcepsilonRI receptors and in normal mice depleted of Gr-1+ immune cell populations known to express FcγR, suggesting protection was largely mediated by an FcγR-dependent mechanism. To test whether neutralizing Ab might provide superior protection, a highly neutralizing HSV glycoprotein D (gD)- specific monoclonal antibody (mAb) was utilized. Similar to results with HSV-specific polyclonal IgG, administration of the gD-specific mAb did not prevent initial infection of the genital tract but resulted in lower virus loads in the vaginal epithelium and provided significant protection against disease and acute infection of the sensory ganglia; however, this protection was independent of host FcγR expression and was manifest in mice depleted of Gr-1+ immune cells. Together, these data demonstrate that substantial Ab-mediated protection against genital HSV-2 disease could be achieved by either FcγR-dependent or -independent mechanisms. These studies suggest that HSV vaccines might need to elicit multiple, diverse antibody effector mechanisms to achieve optimal protection. PMID:17950908

  20. 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

  1. Expression of murine Fc receptors for IgG.

    PubMed

    Schreiber, R E; Buku, A; Unkeless, J C

    1990-06-15

    There are two distinct genes that encode murine low affinity Fc gamma RII, murine Fc gamma RII alpha, and murine Fc gamma RII beta, which are transcribed in specific cell lineages. Fc gamma RII alpha transcripts are present in macrophages, NK cells, and mesangial cells; Fc gamma RII beta transcripts are expressed in Fc gamma R-bearing B cells, T cells, and macrophages. We have devised a sandwich ELISA to quantify the expression of Fc gamma RII alpha protein. The ELISA is specific for Fc gamma RII alpha, and does not detect the closely related Fc gamma RII beta protein. Upon stimulation with IFN-gamma the Fc gamma RII beta- macrophage cell line J774a expressed a twelvefold enhanced level of Fc gamma RII alpha protein. Peritoneal macrophages synthesized varying amounts of Fc gamma RII alpha. High levels of Fc gamma RII alpha were observed in resident and thioglycollate-elicited peritoneal macrophages, but no Fc gamma RII alpha was detected in Bacillus Calmette Guérin-elicited macrophages. J774a cells stimulated with rIL-6 bound approximately twice as much anti-Fc gamma RII mAb 2.4G2 IgG as did unstimulated controls. However, the Fc gamma RII alpha-specific ELISA showed no change in the amount of Fc gamma RII alpha expressed. A probe encompassing the extracellular coding sequence of Fc gamma RII beta hybridized to two distinct transcripts that were elevated in rIL-6-stimulated J774a cells. One of these transcripts had the same mobility in electrophoresis as Fc gamma RII alpha mRNA and hybridized to an Fc gamma RII alpha-specific probe, whereas the other transcript was larger and did not hybridize to probes specific for either Fc gamma RII alpha or Fc gamma RII beta. Moreover, we confirmed, with an Fc gamma RII beta-specific probe, that J774a cells do not make Fc gamma RII beta mRNA. Thus, the larger transcript appears to encode a novel Fc gamma RII. We suggest that the increased level of binding of the anti-Fc gamma RII mAb 2.4G2 to rIL-6-induced cells represents

  2. Interleukin 4 reduces expression of inhibitory receptors on B cells and abolishes CD22 and Fc gamma RII-mediated B cell suppression.

    PubMed

    Rudge, Elizabeth U; Cutler, Antony J; Pritchard, Nicholas R; Smith, Kenneth G C

    2002-04-15

    Inhibitory receptors CD22, Fc gamma RII (CD32), CD72, and paired immunoglobulin-like receptor (PIR)-B are critically involved in negatively regulating the B cell immune response and in preventing autoimmunity. Here we show that interleukin 4 (IL-4) reduces expression of all four on activated B cells at the level of messenger RNA and protein. This reduced expression is dependent on continuous exposure to IL-4 and is mediated through Stat6. Coligation of Fc gamma RII to the B cell receptor (BCR) via intact IgG increases the B cell activation threshold and suppresses antigen presentation. IL-4 completely abolishes these negative regulatory effects of Fc gamma RII. CD22 coligation with the BCR also suppresses activation -- this suppression too is abolished by IL-4. Thus, IL-4 is likely to enhance the B cell immune response by releasing B cells from inhibitory receptor suppression. By this coordinate reduction in expression of inhibitory receptors, and release from CD22 and Fc gamma RII-mediated inhibition, IL-4 is likely to play a role in T cell help of B cells and the development of T helper cell type 2 responses. Conversely, B cell activation in the absence of IL-4 would be more difficult to achieve, contributing to the maintenance of B cell tolerance in the absence of T cell help. PMID:11956299

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. 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

  8. Diagnostic implications of antigen-induced gamma interferon production by blood leukocytes from Mycobacterium bovis-infected reindeer (Rangifer tarandus).

    PubMed

    Waters, W R; Palmer, M V; Slaughter, R E; Jones, S L; Pitzer, J E; Minion, F C

    2006-01-01

    The only approved method of tuberculosis (TB) surveillance of reindeer within the United States is tuberculin skin testing; however, skin testing has an apparent lack of specificity, since numerous reindeer are classified as reactors, yet Mycobacterium bovis is not isolated from tissues upon necropsy. The objective of this study was to evaluate the ability of an in vitro assay (the Cervigam assay) to detect gamma interferon (IFN-gamma) produced by blood leukocytes in response to mycobacterial antigens from M. bovis-infected reindeer. Thirteen male reindeer approximately 9 months of age were inoculated with 10(5) CFU M. bovis in their tonsillar crypts. Stimulation of whole-blood cultures with a mitogen resulted in significant production of IFN-gamma compared to that by nonstimulated samples. Responses by infected reindeer to M. bovis purified protein derivative (PPD) were as much as 3.5-fold higher than those by noninfected reindeer (n = 4). Despite differences in responses to PPD by the two groups, reindeer within the noninfected group had responses of >0.1 change in optical density (DeltaOD) (a level generally considered positive) to PPD. Mean responses by infected reindeer to a rESAT-6-CFP-10 fusion protein (Mycobacterium tuberculosis complex specific) were as much as 20-fold higher than respective responses by noninfected reindeer at all time points. Additionally, responses by 3/4 noninfected reindeer were <0.1 DeltaOD (considered negative) at each time point. To further evaluate the specificity of the assay, samples were collected from reindeer in a TB-free herd. All reindeer had responses to mitogen; however, only 1 of 38 had a response to PPD, and none of the reindeer responded to rESAT-6-CFP-10. Together, these findings indicate that IFN-gamma-based tests may prove useful for TB surveillance of reindeer. PMID:16425998

  9. Fc Gamma Receptor IIA (CD32A) R131 Polymorphism as a Marker of Genetic Susceptibility to Sepsis.

    PubMed

    Beppler, Jaqueline; Koehler-Santos, Patrícia; Pasqualim, Gabriela; Matte, Ursula; Alho, Clarice Sampaio; Dias, Fernando Suparregui; Kowalski, Thayne Woycinck; Velasco, Irineu Tadeu; Monteiro, Renato C; Pinheiro da Silva, Fabiano

    2016-04-01

    Sepsis is a devastating disease that can affect humans at any time between neonates and the elderly and is associated with mortality rates that range from 30 to 80 %. Despite intensive efforts, its treatment has remained the same over the last few decades. Fc receptors regulate multiple immune responses and have been investigated in diverse complex diseases. FcγRIIA (CD32A) is an immunoreceptor, tyrosine-based activation motif-bearing receptor that binds immunoglobulin G and C-reactive protein, important opsonins in host defense. We conducted a study of 702 patients (184 healthy individuals, 171 non-infected critically ill patients, and 347 sepsis patients) to investigate if genetic polymorphisms in the CD32A coding region affect the risk of septic shock. All individuals were genotyped for a variant at position 131 of the FcγRIIA gene. We found that allele G, associated with the R131 genotype, was significantly more frequent in septic patients than in the other groups (p = 0.05). Our data indicate that FcγRIIA genotyping can be used as a marker of genetic susceptibility to sepsis. PMID:26490967

  10. Paired immunoglobulin-like receptor (PIR)-A is involved in activating mast cells through its association with Fc receptor gamma chain.

    PubMed

    Maeda, A; Kurosaki, M; Kurosaki, T

    1998-09-01

    Paired immunoglobulin-like receptor (PIR)-A and PIR-B possess similar ectodomains with six immunoglobulin-like loops, but have distinct transmembrane and cytoplasmic domains. PIR-B bears immunoreceptor tyrosine-based inhibitory motif (ITIM) sequences in its cytoplasmic domain that recruit Src homology (SH)2 domain-containing tyrosine phosphatases SHP-1 and SHP-2, leading to inhibition of B and mast cell activation. In contrast, the PIR-A protein has a charged Arg residue in its transmembrane region and a short cytoplasmic domain that lacks ITIM sequences. Here we show that Fc receptor gamma chain, containing an immunoreceptor tyrosine-based activation motif (ITAM), associates with PIR-A. Cross-linking of this PIR-A complex results in mast cell activation such as calcium mobilization in an ITAM-dependent manner. Thus, our data provide evidence for the existence of two opposite signaling pathways upon PIR aggregation. PIR-A induces the stimulatory signal by using ITAM in the associated gamma chain, whereas PIR-B mediates the inhibitory signal through its ITIMs. PMID:9730901

  11. 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 -...

  12. Tumor metastases and cell-mediated immunity in a model system in DBA/2 mice. VIII. Expression and shedding of Fc gamma receptors on metastatic tumor cell variants.

    PubMed

    Schirrmacher, V; Jacobs, W

    1979-01-01

    The expression of receptors for the Fc portion of IgG immunoglobin molecules was studied on tumor cell lines with high and low metastatic capacity. Two tumor cell lines from DBA/2 mice that had high metastatic activity, ESb and MDAY-D2, contained a high percentage of Fc receptor positive cells, as detected in a rosette assay with IgG antibody-coated erythrocytes (EA). In contrast, the low metastatic parental line Eb, from which ESb was derived, contained only a low percentage of EA-rosette-forming cells. ESb ascites tumor cells adapted to tissue culture in the presence of 2-mercaptoethanol (2ME) had a high expression of Fc receptors, whereas a cell line adapted to tissue culture in the absence of 2ME had a low expression of Fc receptors. "Soluble" Fc receptors were detectable by their ability to bind to EA and to cause blocking of rosette formation. They were found to be present in fluids from tumor-bearing animals, such as serum and cell-free ascites. Even animals with an ascites tumor of the low-metastatic line Eb contained "soluble" Fc receptors. The results are discussed with regard to their possible significance for tumor metastasis. PMID:522481

  13. 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...

  14. Role of polymorphic Fc gamma receptor IIIa and EGFR expression level in cetuximab mediated, NK cell dependent in vitro cytotoxicity of head and neck squamous cell carcinoma cells

    PubMed Central

    López-Albaitero, Andrés; Lee, Steve C.; Morgan, Sarah; Grandis, Jennifer R.; Gooding, William E.; Ferrone, Soldano

    2012-01-01

    Immunotherapy with the EGFR-specific mAb cetuximab is clinically effective in 10–20% of patients with squamous cell carcinoma of the head and neck (SCCHN). Little information is available about the mechanism(s) underlying patients’ differential clinical response to cetuximab-based immunotherapy, although this information may contribute to optimizing the design of cetuximab-based immunotherapy. Our understanding of these mechanisms would benefit from the characterization of the variables which influence the extent of cell dependent-lysis of SCCHN cells incubated with cetuximab in vitro. Therefore, in this study we have investigated the role of FcγR IIIa-158 genotype expressed by effector NK cells, cetuximab concentration, and EGFR expression level by SCCHN cells in the extent of their in vitro lysis and in the degree of NK cell activation. PBMC or purified CD56+ NK cells genotyped at IIIa codon 158 and SCCHN cell lines expressing different levels of EGFR have been used as effectors and targets, respectively, in antibody dependent cellular cytotoxicity (ADCC) assays. Furthermore, supernatants from ADCC assays were analyzed for cytokine and chemokine levels using multiplexed ELISA. We found that the extent of lysis of SCCHN cells was influenced by the EGFR expression level, cetuximab concentration, and FcγR polymorphism. Effector cells expressing the FcγR IIIa-158 VV allele were significantly (P < 0.0001) more effective than those expressing FcγR IIIa VF and VV alleles in mediating lysis of SCCHN cells expressed higher levels of the activation markers CD69 and CD107a, and secreted significantly (P < 0.05) larger amounts of inflammatory cytokines and chemokines. IL-2 or IL-15 treatment increased cetuximab-mediated ADCC by poor binding FcγR IIIa 158 FF expressing NK cells. The importance of the FcγR IIIa-158 polymorphism in cytotoxicity of SCCHN cells by NK cells supports a potential role for immune activation and may explain patient variability of cetuximab

  15. 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...

  16. Prognostic significance of the heterogenous expression of IgG Fc receptors in B-cell chronic lymphocytic leukemia.

    PubMed

    Schranz, V; Gráf, F

    1992-03-01

    Receptors for the Fc part of IgG (Fc gamma R) are expressed in three forms on peripheral blood lymphocytes. The presence of the releasable form (Fc gamma R(REL.)) as well as of the two nonreleasable forms with lower (Fc gamma R(LOW)) and higher (Fc gamma R(HIGH)) cellular avidity was correlated with survival in 63 patients with B-cell chronic lymphocytic leukemia (B-CLL). High percentage of cells with Fc gamma R(LOW) as well as high "absolute" number of cells carrying the two nonreleasable forms of Fc gamma R were connected to unfavorable prognosis. Combining these three parameters, an Fc gamma R constellation was defined which pointed to a favorable prognosis (in 24 patients) when all three parameters were low, but detected short survivors when all three data were high (in 14 patients). The Fc gamma R constellation was capable of identifying patients with better or worse prognosis within groups that were homogeneous regarding some other known prognostic factors. Fc gamma R constellation as a prognostic factor was shown to be independent of age, sex, and Rai and Binet stages, but it was found to be connected with the total tumor mass score (TTM). The three forms of Fc gamma R on B cells might reflect stages of B-cell activation. Differences in Fc gamma R constellations between patients with B-CLL would thus correspond to differently activated B-cell clones with variable prognosis. PMID:1571409

  17. Inhibition by synthetic peptides from human IgG Fc of OKT4 binding and Fc receptor binding

    SciTech Connect

    Gaarde, W.A.; McClurg, M.R.; Hahn, G.S.; Plummer, J.M.

    1986-03-05

    Synthetic peptides from the Fc region of human IgG were tested for the ability to inhibit IgG rosette formation, /sup 125/I-IgG binding to Fc receptors on lymphocytes, and expression of the T4 cell determinant. The Fc/sub ..gamma../ peptides inhibited IgG rosette formation and competitively inhibited both /sup 125/I-IgG binding to Fc receptors and OKT4 binding to the T4 cell determinant. Peptides containing D-amino acids did not inhibit IgG rosettes, OKT4 binding or /sup 125/I-IgG binding. OKT4 binding to T4 on MNC was inhibited by heat aggregated IgG but not by monomeric IgG. OKT3, OKT8 and OKT11 binding to their determinants was not altered by Fc/sub ..gamma../ peptides, aggregated IgG or monomeric IgG. These results suggest that T4 antigen, Fc receptor for IgG and the Fc/sub ..gamma../ peptide binding site are in close proximity on the cell surface and when occupied by their respective ligands may sterically hinder binding to other sites. Alternatively, Fc/sub ..gamma../ peptides may indirectly regulate cell surface expression of T4 and/or Fc receptors for IgG. These Fc/sub ..gamma../ peptides inhibit the MLR, inhibit antigen induced T cell proliferation and reverse animal models of autoimmune disease. The immunoregulatory activities of these peptides may be related to their selective action on T4 helper/inducer lymphocytes expressing Fc receptors.

  18. Intravenous immunoglobulins modulate neutrophil activation and vascular injury through FcγRIII and SHP-1

    PubMed Central

    Jang, Jung-Eun; Hidalgo, Andrés; Frenette, Paul S.

    2012-01-01

    Rationale Intravascular neutrophil recruitment and activation are a key pathogenic factor that contributes to vascular injury. Intravenous immunoglobulin (IVIG) has been shown to have a beneficial effect in systemic inflammatory disorders; however, the mechanisms underlying IVIG’s inhibitory effect on neutrophil recruitment and activation are not understood. Objective We studied the mechanisms by which IVIG exerts protection from neutrophil-mediated acute vascular injury. Methods and Results We examined neutrophil behavior in response to IVIG in vivo using real time intravital microscopy. We found that an antibody that blocks both FcγRIII and its inhibitory receptor counterpart, FcγRIIB, abrogated the inhibitory effect of IVIG on leukocyte recruitment and heterotypic RBC interactions with adherent leukocytes in wild-type mice. In the context of sickle cell disease, the blockade of both FcγRIIB and III abrogated the protective effect of IVIG on acute vaso-occlusive crisis caused by neutrophil recruitment and activation. Analysis of FcγRIIB- and FcγRIII-deficient mice revealed the predominant expression of FcγRIII on circulating neutrophils. FcγRIII mediated IVIG-triggered inhibition of leukocyte recruitment, circulating RBC capture, and enhanced Mac-1 activity, whereas FcγRIIB was dispensable. In addition, FcγRIII-induced IVIG anti-inflammatory activity in neutrophils was mediated by recruitment of Src homology 2 (SH2)-containing tyrosine phosphatase-1 (SHP-1). Indeed, the protective effect of IVIG on leukocyte recruitment and activation was abrogated in SHP-1-mutant mice. Conclusions FcγRIII, a classical activating receptor, has an unexpected inhibitory role on neutrophil adhesion and activation via recruitment of SHP-1 in response to IVIG. Our results identify SHP-1 as a therapeutic target in neutrophil-mediated vascular injury. PMID:22415018

  19. A Comparison of Assays for Accurate Copy Number Measurement of the Low-Affinity Fc Gamma Receptor Genes FCGR3A and FCGR3B

    PubMed Central

    Haridan, Umi Shakina; Mokhtar, Umairah; Machado, Lee R.; Abdul Aziz, Abu Thalhah; Shueb, Rafidah Hanim; Zaid, Masliza; Sim, Benedict; Mustafa, Mahiran; Nik Yusof, Nik Khairudin; Lee, Christopher K. C.; Abu Bakar, Suhaili; AbuBakar, Sazaly; Hollox, Edward J.; Boon Peng, Hoh

    2015-01-01

    The FCGR3 locus encoding the low affinity activating receptor FcγRIII, plays a vital role in immunity triggered by cellular effector and regulatory functions. Copy number of the genes FCGR3A and FCGR3B has previously been reported to affect susceptibility to several autoimmune diseases and chronic inflammatory conditions. However, such genetic association studies often yield inconsistent results; hence require assays that are robust with low error rate. We investigated the accuracy and efficiency in estimating FCGR3 CNV by comparing Sequenom MassARRAY and paralogue ratio test-restriction enzyme digest variant ratio (PRT-REDVR). In addition, since many genetic association studies of FCGR3B CNV were carried out using real-time quantitative PCR, we have also included the evaluation of that method’s performance in estimating the multi-allelic CNV of FCGR3B. The qPCR assay exhibited a considerably broader distribution of signal intensity, potentially introducing error in estimation of copy number and higher false positive rates. Both Sequenom and PRT-REDVR showed lesser systematic bias, but Sequenom skewed towards copy number normal (CN = 2). The discrepancy between Sequenom and PRT-REDVR might be attributed either to batch effects noise in individual measurements. Our study suggests that PRT-REDVR is more robust and accurate in genotyping the CNV of FCGR3, but highlights the needs of multiple independent assays for extensive validation when performing a genetic association study with multi-allelic CNVs. PMID:25594501

  20. Fc-fusion mimetics.

    PubMed

    Khalili, H; Khaw, P T; Brocchini, S

    2016-06-24

    The Fc-fusion mimetic RpR 2[combining low line] was prepared by disulfide bridging conjugation using PEG in the place of the Fc. RpR 2[combining low line] displayed higher affinity for VEGF than aflibercept. This is caused primarily by a slower dissociation rate, which can prolong a drug at its site of action. RpRs have considerable potential for development as stable, organ specific therapeutics. PMID:27127811

  1. Interleukin-4 production by Fc epsilon R+ cells.

    PubMed

    Paul, W E

    1991-01-01

    Among non-B, non-T cells in the spleen and among unfractionated bone marrow cells, there is a population of cells that are capable of producing IL-4 in response to cross-linkage of FC epsilon RI or Fc gamma RII. Their IL-4-producing capacity is strikingly enhanced by treatment of the cells or of the animals donating such cells with interleukin-3 (IL-3). Fc epsilon R+ cells constitute 1-2% of splenic non-B, non-T cells and of bone marrow cells from normal donors but they contain all the capacity to produce IL-4 in response to cross-linkage of Fc epsilon RI or Fc gamma RII or to treatment with ionomycin. Fc epsilon R- cells fail to make such responses. Electron-microscopic analysis indicates that virtually all the granulated or vacuolated Fc epsilon R+ cells are of the basophil lineage. However, it has not yet been resolved whether these cells or immature mast cells, presumably in the Fc epsilon R+ granule/vacuole-negative cell population, are the principal producers of IL-4 in response to these stimuli. PMID:1837220

  2. Chimaeric Lym-1 monoclonal antibody-mediated cytolysis by neutrophils from G-CSF-treated patients: stimulation by GM-CSF and role of Fc gamma -receptors.

    PubMed

    Ottonello, L; Epstein, A L; Mancini, M; Tortolina, G; Dapino, P; Dallegri, F

    2001-08-01

    Chimaeric Lym-1 (chLym-1) is a monoclonal antibody generated by fusing the variable region genes of murine Lym-1 to human gamma1 and kappa constant regions. Owing to its selectivity and avidity for human malignant B cells, it is an attractive candidate for developing immune-interventions in B-lymphomas. In the attempt to identify rational bases for optimizing potential chLym-1 related therapeutic approaches, we studied the ability of this ch-mAb to trigger neutrophil-mediated Raji cell cytolysis in cooperation with two neutrophil-related cytokines, G-CSF and GM-CSF. ChLym-1 triggered low levels of cytolysis by normal neutrophils but induced consistent cytolysis in neutrophils from individuals treated with G-CSF. When exposed to GM-CSF, neutrophils from subjects treated with G-CSF became potent effectors, also leading to 75% lysis. By using mAbs specific for distinct FcgammaRs, normal neutrophils were inhibited by mAb IV.3, suggesting the intervention of FcgammaRII, constitutively expressed on the cells. On the other hand, neutrophils from patients treated with G-CSF were inhibited by mAb IV.3 plus mAb 197, a finding consistent with a cooperative intervention of FCgammaRII and G-CSF-induced FcgammaRI. The anti-FcgammaRIII mAb 3G8 promoted significant enhancement of the neutrophil cytolytic efficiency. Therefore, neutrophil FcgammaRIII behaves as a down-regulator of the cytolytic potential. The present findings suggest new attempts to develop mAb-based and G-CSF/GM-CSF combined immune-interventions in B lymphomas. PMID:11487281

  3. Molecular recognition of antibody (IgG) by cellular Fc receptor (FcRI).

    PubMed

    Burton, D R; Jefferis, R; Partridge, L J; Woof, J M

    1988-11-01

    Earlier studies from this and other laboratories have provided indirect evidence for the involvement of the C gamma 2 domain of human IgG in the binding of IgG to the high affinity monocyte Fc receptor (FcRI). Two approaches have been used to extend these studies and to further localize the site of interaction on human IgG. Firstly, monoclonal antibodies (MAbs) directed against different epitopes on IgG were assayed for their capacity to inhibit the binding of radiolabelled IgG to human monocytes or U937 cells. The capacity of the MAbs to interact with their respective epitopes on FcR-bound IgG was also studied using indirect radiobinding and immunofluorescence assays. Secondly, a number of IgGs from several different species and fragments of human IgGs were assayed for their ability to inhibit the binding of radiolabelled IgG to human monocytes. The amino acid sequences of those IgGs exhibiting relatively tight, intermediate or weak binding to monocyte FcRs were compared. On the basis of these studies a possible monocyte FcR-binding site on human IgG is postulated, involving the lower hinge region of IgG (residues Leu 234-Ser 239) with possible involvement of the nearby N-proximal bend and two beta-strands (Gly 316-Lys 338). PMID:2975762

  4. The melanocortin system in leukocyte biology.

    PubMed

    Catania, Anna

    2007-02-01

    The melanocortin system is composed of the melanocortin peptides, adrenocorticotropic hormone and alpha-, beta-, and gamma-melanocyte-stimulating hormone, the melanocortin receptors (MCRs), and the endogenous antagonists agouti- and agouti-related protein. Melanocortin peptides exert multiple effects upon the host, including anti-inflammatory and immunomodulatory effects. Leukocytes are a source of melanocortins and a major target for these peptides. Because of reduced translocation of the nuclear factor NF-kappaB to the nucleus, MCR activation by their ligands causes a collective reduction of the most important molecules involved in the inflammatory process. This review examines how melanocortin peptides and their receptors participate in leukocyte biology. PMID:17041004

  5. The human IgA-Fc alpha receptor interaction and its blockade by streptococcal IgA-binding proteins.

    PubMed

    Woof, J M

    2002-08-01

    IgA plays a key role in immune defence of the mucosal surfaces. IgA can trigger elimination mechanisms against pathogens through the interaction of its Fc region with Fc alpha Rs (receptors specific for the Fc region of IgA) present on neutrophils, macrophages, monocytes and eosinophils. The human Fc alpha R (CD89) shares homology with receptors specific for the Fc region of IgG (Fc gamma Rs) and IgE (Fc epsilon RIs), but is a more distantly related member of the receptor family. CD89 interacts with residues lying at the interface of the two domains of IgA Fc, a site quite distinct from the homologous regions at the top of IgG and IgE Fc recognized by Fc gamma R and Fc epsilon RI respectively. Certain pathogenic bacteria express surface proteins that bind to human IgA Fc. Experiments with domain-swap antibodies and mutant IgAs indicate that binding of three such proteins (Sir22 and Arp4 of Streptococcus pyogenes and beta protein of group B streptococci) depend on sites in the Fc interdomain region of IgA, the binding region also used by CD89. Further, we have found that the streptococcal proteins can inhibit interaction of IgA with CD89, and have thereby identified a mechanism by which a bacterial IgA-binding protein may modulate IgA effector function. PMID:12196121

  6. Leukocyte relaxation properties.

    PubMed Central

    Sung, K L; Dong, C; Schmid-Schönbein, G W; Chien, S; Skalak, R

    1988-01-01

    Study of the mechanical properties of leukocytes is useful to understand their passage through narrow capillaries and interaction with other cells. Leukocytes are known to be viscoelastic and their properties have been established by micropipette aspiration techniques. Here, the recovery of leukocytes to their normal spherical form is studied after prolonged deformation in a pipette which is large enough to permit complete entry of the leukocyte. The recovery history is characterized by the time history of the major diameter (d1) and minor diameter (d2). When the cell is removed from the pipette, it shows initially a small rapid recoil followed by a slower asymptotic recovery to the spherical shape. In the presence of cell activation and formation of pseudopods, the time history for recovery is prolonged compared with passive cell recovery. If a protopod pre-existed during the holding period, the recovery only begins when the protopod starts to retract. Images FIGURE 1 PMID:3207829

  7. Notice of Release of FC1018, FC1019, FC1020 and FC1022 Multigerm Sugarbeet Germplasms with Multiple Disease Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    FC1018 (PI 658059) has excellent resistance to root-rotting strains (AG-2-2) of Rhizoctonia solani Kühn and carries the Rz1 gene, which confers resistance to some strains of Beet necrotic yellow vein virus (BNYVV), the causal agent of rhizomania. FC1018 has shown a moderate tolerance to cercospora ...

  8. Human neutrophil Fc receptor-mediated adhesion under flow: a hollow fibre model of intravascular arrest.

    PubMed

    D'Arrigo, C; Candal-Couto, J J; Greer, M; Veale, D J; Woof, J M

    1995-04-01

    Human polymorphonuclear cells (PMN) were found to adhere to a novel model of blood vessel wall-associated IgG. The internal surfaces of cellulose acetate hollow fibres, of comparable internal diameter to small blood vessels, were coated with normal serum human IgG, heat-aggregated IgG (HAIgG), laminin or fibrinogen. Under conditions of flow mimicking those in a small vessel, PMN were found to adhere markedly only to immunoglobulin-coated fibres. Arrest on HAIgG was inhibited by excess soluble IgG but not by bovine serum albumin (BSA), demonstrating that the adhesion was IgG-specific and presumably mediated by Fc gamma R on the PMN surface. Pre-adsorption of serum components onto HAIgG-coated fibres enhanced PMN arrest, due most probably to fixation of complement components by immobilized HAIgG, resulting in additional potential to entrap PMN via complement receptors such as CR3. Treatment of PMN with the regulatory neuropeptide substance P also enhanced adhesion to HAIgG-coated fibres and caused increased surface expression of Fc gamma RI, Fc gamma RII and Fc gamma RIII. A mouse cell line derived from L cells, hR4C6, stably transfected with human Fc gamma RII, was found to adhere under flow to HAIgG-coated fibres, whilst untransfected parent L cells did not. This adhesion was similarly inhibited by excess soluble IgG, confirming the capability of Fc gamma R to mediate cell arrest. The study strongly suggests that Fc gamma R may play an important role in intravascular PMN arrest and we speculate that in inflammatory diseases PMN may adhere via Fc gamma R to immobilized immunoglobulin on the vascular endothelium, with subsequent degranulation and tissue damage. PMID:7535210

  9. 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.

  10. Biomechanics of leukocyte rolling.

    PubMed

    Sundd, Prithu; Pospieszalska, Maria K; Cheung, Luthur Siu-Lun; Konstantopoulos, Konstantinos; Ley, Klaus

    2011-01-01

    Leukocyte rolling on endothelial cells and other P-selectin substrates is mediated by P-selectin binding to P-selectin glycoprotein ligand-1 expressed on the tips of leukocyte microvilli. Leukocyte rolling is a result of rapid, yet balanced formation and dissociation of selectin-ligand bonds in the presence of hydrodynamic shear forces. The hydrodynamic forces acting on the bonds may either increase (catch bonds) or decrease (slip bonds) their lifetimes. The force-dependent 'catch-slip' bond kinetics are explained using the 'two pathway model' for bond dissociation. Both the 'sliding-rebinding' and the 'allosteric' mechanisms attribute 'catch-slip' bond behavior to the force-induced conformational changes in the lectin-EGF domain hinge of selectins. Below a threshold shear stress, selectins cannot mediate rolling. This 'shear-threshold' phenomenon is a consequence of shear-enhanced tethering and catch bond-enhanced rolling. Quantitative dynamic footprinting microscopy has revealed that leukocytes rolling at venular shear stresses (>0.6 Pa) undergo cellular deformation (large footprint) and form long tethers. The hydrodynamic shear force and torque acting on the rolling cell are thought to be synergistically balanced by the forces acting on tethers and stressed microvilli, however, their relative contribution remains to be determined. Thus, improvement beyond the current understanding requires in silico models that can predict both cellular and microvillus deformation and experiments that allow measurement of forces acting on individual microvilli and tethers. PMID:21515934

  11. Neonatal Fc Receptor Mediates Internalization of Fc in Transfected Human Endothelial Cells

    PubMed Central

    Goebl, Nancy A.; Babbey, Clifford M.; Datta-Mannan, Amita; Witcher, Derrick R.; Wroblewski, Victor J.

    2008-01-01

    The neonatal Fc receptor, FcRn mediates an endocytic salvage pathway that prevents degradation of IgG, thus contributing to the homeostasis of circulating IgG. Based on the low affinity of IgG for FcRn at neutral pH, internalization of IgG by endothelial cells is generally believed to occur via fluid-phase endocytosis. To investigate the role of FcRn in IgG internalization, we used quantitative confocal microscopy to characterize internalization of fluorescent Fc molecules by HULEC-5A lung microvascular endothelia transfected with GFP fusion proteins of human or mouse FcRn. In these studies, cells transfected with FcRn accumulated significantly more intracellular Fc than untransfected cells. Internalization of FcRn-binding forms of Fc was proportional to FcRn expression level, was enriched relative to dextran internalization in proportion to FcRn expression level, and was blocked by incubation with excess unlabeled Fc. Because we were unable to detect either surface expression of FcRn or surface binding of Fc, these results suggest that FcRn-dependent internalization of Fc may occur through sequestration of Fc by FcRn in early endosomes. These studies indicate that FcRn-dependent internalization of IgG may be important not only in cells taking up IgG from an extracellular acidic space, but also in endothelial cells participating in homeostatic regulation of circulating IgG levels. PMID:18843053

  12. Changes in Healthy Human IgG Fc-Glycosylation after Birth and during Early Childhood.

    PubMed

    de Haan, Noortje; Reiding, Karli R; Driessen, Gertjan; van der Burg, Mirjam; Wuhrer, Manfred

    2016-06-01

    Glycosylation on the fragment crystallizable (Fc) region of immunoglobulin G (IgG) has a large influence on the interaction of the antibody with Fc gamma receptors (FcγRs). IgG consists of four subclasses that all have distinct affinities for the different FcγRs. Knowledge about the Fc-glycosylation in healthy human is valuable as reference for new biomarkers and in the design of biopharmaceuticals that rely on IgG Fc-glycosylation. Previously, subclass-specific characterization of IgG Fc-glycosylation was performed for healthy adults, pregnant women, and newborns. For young healthy children, however, the subclass-specific description of IgG Fc-glycosylation is still lacking. Therefore, we performed the IgG subclass-specific analysis of the Fc-glycosylation of 130 healthy humans between birth and 40 years of age, including 22 samples derived from the umbilical cords of newborns. The analysis was performed by a previously published matrix-assisted laser desorption/ionization (MALDI)-time-of-flight (TOF)-mass spectrometry (MS) workflow, including a derivatization step for the linkage-specific stabilization of sialic acids. The characterization revealed that when children start to produce their own IgG they have a decreased galactosylation, sialylation, and bisection and an increased fucosylation compared with newborns. During childhood, the fucosylation and sialylation decrease, whereas bisection increases and galactosylation stays constant. PMID:27161864

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

    PubMed

    Chan, Kuan Rong; Ong, Eugenia Z; Mok, Darren Z L; 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

  14. 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

  15. Soluble Monomeric IgG1 Fc*

    PubMed Central

    Ying, Tianlei; Chen, Weizao; Gong, Rui; Feng, Yang; Dimitrov, Dimiter S.

    2012-01-01

    Antibody fragments are emerging as promising biopharmaceuticals because of their relatively small size and other unique properties. However, compared with full-size antibodies, these antibody fragments lack the ability to bind the neonatal Fc receptor (FcRn) and have reduced half-lives. Fc engineered to bind antigens but preserve interactions with FcRn and Fc fused with monomeric proteins currently are being developed as candidate therapeutics with prolonged half-lives; in these and other cases, Fc is a dimer of two CH2-CH3 chains. To further reduce the size of Fc but preserve FcRn binding, we generated three human soluble monomeric IgG1 Fcs (mFcs) by using a combination of structure-based rational protein design combined with multiple screening strategies. These mFcs were highly soluble and retained binding to human FcRn comparable with that of Fc. These results provide direct experimental evidence that efficient binding to human FcRn does not require human Fc dimerization. The newly identified mFcs are promising for the development of mFc fusion proteins and for novel types of mFc-based therapeutic antibodies of small size and long half-lives. PMID:22518843

  16. Breeding for Multiple Disease Resistance in Sugarbeet: Registration of FC220 and FC221

    Technology Transfer Automated Retrieval System (TEKTRAN)

    FC220’ and ‘FC221’ (PI 651015 and PI 651016) sugarbeet germplasms (Beta vulgaris L.) were released from 05-FC1030-15 (Sp) and 05-FC1030-16 (Sp) seed lots, respectively, and tested under those designations and as 03-FC1030-15 and 03-FC1030-16, respectively. They were developed by the USDA-ARS, at F...

  17. 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.

  18. 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

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

    PubMed

    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

  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. Tissue expression profile of human neonatal Fc receptor (FcRn) in Tg32 transgenic mice.

    PubMed

    Fan, Yao-Yun; Avery, Lindsay B; Wang, Mengmeng; O'Hara, Denise M; Leung, Sheldon; Neubert, Hendrik

    2016-07-01

    The neonatal Fc receptor (FcRn) is a homeostatic receptor responsible for prolonging immunoglobulin G (IgG) half-life by protecting it from lysosomal degradation and recycling it to systemic circulation. Tissue-specific FcRn expression is a critical parameter in physiologically-based pharmacokinetic (PBPK) modeling for translational pharmacokinetics of Fc-containing biotherapeutics. Using online peptide immuno-affinity chromatography coupled with high resolution mass spectrometry, we established a quantitative FcRn tissue protein expression profile in human FcRn (hFcRn) transgenic mice, Tg32 homozygous and hemizygous strains. The concentration of hFcRn across 14 tissues ranged from 3.5 to 111.2 pmole per gram of tissue. Our hFcRn quantification data from Tg32 mice will enable a more refined PBPK model to improve the accuracy of human PK predictions for Fc-containing biotherapeutics. PMID:27104806

  2. 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

  3. Superoxide production by phagocytic leukocytes.

    PubMed

    Drath, D B; Karnovsky, M L

    1975-01-01

    Mononuclear phagocytic leukocytes, as well as polymorphonuclear leukocytes, produce and release superoxide at rest, and this is stimulated by phagocytosis. Of the mouse monocytic cells studied, alveolar macrophages released the largest amounts of superoxide during phagocytosis, followed by normal peritoneal macrophages. Casein-elicited and "activated" macrophages released smaller quantities. In the guinea pig, polymorphonuclear leukocytes and casein-elicited macrophages were shown to release superoxide during phagocytosis whereas alveolar macrophages did not. Superoxide release accounted for only a small fraction of the respiratory burst of phagocytosis in all but the normal mouse peritoneal macrophage, the guinea pig polymorphonuclear leukocyte, and probably the mouse alveolar macrophage. There are obviously considerable species differences in O2-release by various leukocytes that might reflect both the production and/or destruction (e.g. by dismutase) of that substance. PMID:804030

  4. Leukocyte biophysics. An invited review.

    PubMed

    Schmid-Schönbein, G W

    1990-10-01

    The biophysical properties of leukocytes in the passive and active state are discussed. In the passive unstressed state, leukocytes are spherical with numerous membrane folds. Passive leukocytes exhibit viscoelastic properties, and the stress is carried largely by the cell cytoplasm and the nucleus. The membrane is highly deformable in shearing and bending, but resists area expansion. Membrane tension can usually be neglected but plays a role in cases of large deformation when the membrane becomes unfolded. The constant membrane area constraint is a determinant of phagocytic capacity, spreading of cells, and passage through narrow pores. In the active state, leukocytes undergo large internal cytoplasmic deformation, pseudopod projection, and granule redistribution. Several different measurements for assessment of biophysical properties and the internal cytoplasmic deformation in form of strain and strain rate tensors are presented. The current theoretical models for active cytoplasmic motion in leukocytes are discussed in terms of specific macromolecular reactions. PMID:1705479

  5. Functional and clinical consequences of Fc receptor polymorphic and copy number variants.

    PubMed

    Bournazos, S; Woof, J M; Hart, S P; Dransfield, I

    2009-08-01

    Receptors for immunoglobulins (Fc receptors) play a central role during an immune response, as they mediate the specific recognition of antigens of almost infinite diversity by leucocytes, thereby linking the humoral and cellular components of immunity. Indeed, engagement of Fc receptors by immunoglobulins initiates a range of immunoregulatory processes that might also play a role in disease pathogenesis. In the circulation, five main types of immunoglobulins (Ig) exist - namely IgG, IgA, IgE, IgM and IgD and receptors with the ability to recognize and bind to IgG (Fc gamma receptor family), IgE (Fc epsilon RI and CD23), IgA (CD89; Fc alpha/microR) and IgM (Fc alpha/microR) have been identified and characterized. However, it is astonishing that nearly all the known human Fc receptors display extensive genetic variation with clear implications for their function, thus representing a substantial genetic risk factor for the pathogenesis of a range of chronic inflammatory disorders. PMID:19604264

  6. Micropatterned ligand arrays to study spatial regulation in Fc receptor signaling

    PubMed Central

    Torres, Alexis J.; Holowka, David

    2013-01-01

    Summary Fc receptor signaling plays a fundamental role in the adaptive immune response. A plethora of Fc receptors (e.g. Fc gamma, Fc-alpha and Fc-epsilon) are expressed on different immune cells, including natural killer cells, macrophages, mast cells and neutrophils. Receptor clustering and activation by multivalent ligands or opsonized particles induces a signaling cascade that leads to targeted secretion of chemical mediators (i.e. histamine, cytokines and chemokines) and phagocytosis, among other responses. Spatial targeting and compartmentalization are common mechanisms of regulation in Fc receptor signaling. However, the tools for studying these dynamic interactions have been limited. To overcome these limitations in our model system, microfabricated surfaces containing spatially defined ligands are used to cluster and activate IgE receptors (FcεRI), involved in allergic responses by mast cells. Micron-scale control of cell activation allows investigation of spatially regulated mechanisms for intracellular signaling with fluorescence microscopy. This approach in conjunction with biochemical techniques has proven to be valuable for investigating immune receptor signaling. PMID:21701976

  7. 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. PMID:26254986

  8. Chimeric Antigen Receptors With Mutated IgG4 Fc Spacer Avoid Fc Receptor Binding and Improve T Cell Persistence and Antitumor Efficacy

    PubMed Central

    Jonnalagadda, Mahesh; Mardiros, Armen; Urak, Ryan; Wang, Xiuli; Hoffman, Lauren J; Bernanke, Alyssa; Chang, Wen-Chung; Bretzlaff, William; Starr, Renate; Priceman, Saul; Ostberg, Julie R; Forman, Stephen J; Brown, Christine E

    2015-01-01

    The success of adoptive therapy using chimeric antigen receptor (CAR)–expressing T cells partly depends on optimal CAR design. CARs frequently incorporate a spacer/linker region based on the constant region of either IgG1 or IgG4 to connect extracellular ligand-binding with intracellular signaling domains. Here, we evaluated the potential for the IgG4-Fc linker to result in off-target interactions with Fc gamma receptors (FcγRs). As proof-of-principle, we focused on a CD19-specific scFv-IgG4-CD28-zeta CAR and found that, in contrast to CAR-negative cells, CAR+ T cells bound soluble FcγRs in vitro and did not engraft in NSG mice. We hypothesized that mutations to avoid FcγR binding would improve CAR+ T cell engraftment and antitumor efficacy. Thus, we generated CD19-specific CARs with IgG4-Fc spacers that had either been mutated at two sites (L235E; N297Q) within the CH2 region (CD19R(EQ)) or incorporated a CH2 deletion (CD19Rch2Δ). These mutations reduced binding to soluble FcγRs without altering the ability of the CAR to mediate antigen-specific lysis. Importantly, CD19R(EQ) and CD19Rch2Δ T cells exhibited improved persistence and more potent CD19-specific antilymphoma efficacy in NSG mice. Together, these studies suggest that optimal CAR function may require the elimination of cellular FcγR interactions to improve T cell persistence and antitumor responses. PMID:25366031

  9. 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.

  10. 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.

  11. 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...

  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, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 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. Targeting the Fc receptor in autoimmune disease

    PubMed Central

    Li, Xinrui; Kimberly, Robert P

    2014-01-01

    Introduction The Fc receptors and their interaction with immunoglobulin and innate immune opsonins such as CRP are key players in humoral and cellular immune responses. As the effector mechanism for some therapeutic monoclonal antibodies and often a contributor to the pathogenesis and progression of autoimmunity, FcRs are promising targets for treating autoimmune diseases. Areas covered This review discusses the nature of different Fc receptors and the various mechanisms of their involvement in initiating and modulating immunocyte functions and their biological consequences. It describes a range of current strategies in targeting Fc receptors and manipulating their interaction with specific ligands while presenting the pros and cons of these approaches. This review also discusses potential new strategies including regulation of FcR expression and receptor cross-talk. Expert opinion Fc receptors are appealing targets in the treatment of inflammatory autoimmune diseases. However, there are still knowledge limitations and technical challenges, the most important being a better understanding of the individual roles of each of the Fc receptors and enhancement of the specificity in targeting particular cell types and specific Fc receptors. PMID:24521454

  17. Phenotyping of Leukocytes and Leukocyte-Derived Extracellular Vesicles

    PubMed Central

    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. PMID:27195303

  18. Monoclonal antibody (H107) inhibiting IgE binding to Fc epsilon R(+) human lymphocytes.

    PubMed

    Noro, N; Yoshioka, A; Adachi, M; Yasuda, K; Masuda, T; Yodoi, J

    1986-08-15

    A hybridoma-producing monoclonal antibody blocking the binding of human IgE to lymphocytes Fc receptor (Fc epsilon R) was established by the fusion of murine myeloma cells. P3X63.653.Ag8, with BALB/c spleen cells immunized with Fc epsilon R(+) human B lymphoblastoid cell line cells, RPMI1788. A clone of the hybridoma (H107) produced a monoclonal IgG2b antibody that inhibited the rosette formation of Fc epsilon R(+) human B lymphoblastoid cell line cells (RPMI1788, RPMI8866, CESS, Dakiki, and IM9) with fixed ox red blood cells (ORBC) conjugated with human IgE (IgE-ORBC). In contrast, the rosette formation with IgG-conjugated ORBC (IgG-ORBC) on Fc gamma R(+), Fc epsilon R(-) Daudi cells were not affected by the H107 antibodies. A close association of Fc epsilon R and the antigenic determinant recognized by H107 antibody was suggested by the following results. First, the bindings of 125I-labeled IgE (125I-IgE) or 125I-labeled H107 IgG2b antibody (125I-H107) to RPMI8866 cells were inhibited by cold human IgE and H107 IgG2b but not by other classes of human Ig (IgA and IgG), MPC11 IgG2b, or unrelated monoclonal antibodies. Second, H107 antibody reacted with Fc epsilon R(+) B cell lines but not with Fc epsilon R(-) B cell lines as determined by an indirect immunofluorescence. Third, Fc epsilon R(+) cells were depleted by the incubation in the dish coated with H107 antibody or IgE but not in the dish coated with unrelated antibodies. Finally, there was a correlation between the increase of Fc epsilon R(+) cells and that of H107(+) cells in the peripheral blood lymphocytes of the patients with atopic dermatitis. The surface antigens on Fc epsilon R(+) RPMI8866 cells recognized by H107 antibodies had the molecular size of 45,000 as determined by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. PMID:2942602

  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. Identity of the elusive IgM Fc receptor (FcμR) in humans

    PubMed Central

    Oka, Satoshi; Kubagawa, Yoshiki; Torii, Ikuko; Takayama, Eiji; Kang, Dong-Won; Gartland, G. Larry; Bertoli, Luigi F.; Mori, Hiromi; Takatsu, Hiroyuki; Kitamura, Toshio; Ohno, Hiroshi; Wang, Ji-Yang

    2009-01-01

    Although Fc receptors (FcRs) for switched immunoglobulin (Ig) isotypes have been extensively characterized, FcR for IgM (FcμR) has defied identification. By retroviral expression and functional cloning, we have identified a complementary DNA (cDNA) encoding a bona fide FcμR in human B-lineage cDNA libraries. FcμR is defined as a transmembrane sialoglycoprotein of ∼60 kD, which contains an extracellular Ig-like domain homologous to two other IgM-binding receptors (polymeric Ig receptor and Fcα/μR) but exhibits an exclusive Fcμ-binding specificity. The cytoplasmic tail of FcμR contains conserved Ser and Tyr residues, but none of the Tyr residues match the immunoreceptor tyrosine-based activation, inhibitory, or switch motifs. Unlike other FcRs, the major cell types expressing FcμR are adaptive immune cells, including B and T lymphocytes. After antigen-receptor ligation or phorbol myristate acetate stimulation, FcμR expression was up-regulated on B cells but was down-modulated on T cells, suggesting differential regulation of FcμR expression during B and T cell activation. Although this receptor was initially designated as Fas apoptotic inhibitory molecule 3, or TOSO, our results indicate that FcμR per se has no inhibitory activity in Fas-mediated apoptosis and that such inhibition is only achieved when anti-Fas antibody of an IgM but not IgG isotype is used for inducing apoptosis. PMID:19858324

  1. Elemental composition of leukocyte subfractions

    NASA Astrophysics Data System (ADS)

    Admans, L. L.; Spyrou, N. M.

    2003-01-01

    The aim of this preliminary investigation was to determine the elemental concentration of various subfractions of leukocytes in a normal subject. Little work has been published on the elemental composition of these subfractions. First, a reliable technique for separation of these subfractions had to be established so that it could be applied to the determination of elemental concentrations in leukocyte subfractions from patients undergoing heart bypass surgery. Instrumental neutron activation analysis (INAA) utilising short irradiation and counting was the technique employed. Various washing media were examined during the separation of the leukocyte subfractions, for contamination of these small samples of peripheral blood mononuclear cells (PBMC) and polymorphonuclearcytes (PMN). Early results showed Mg and Se were present in these subfractions. Possibilities for further work are also discussed.

  2. Fc receptors and immunity to parasites.

    PubMed

    Pleass, R J; Woof, J M

    2001-11-01

    Fc receptors (FcRs) are crucial in the immune system; they mediate a plethora of biological functions as diverse as antigen presentation, phagocytosis, cytotoxicity, induction of inflammatory cascades and modulation of immune responses. Parasites, in order to survive in the immunocompetent host, have devised ingenious methods to subvert this important aspect of the immune response. This article discusses the current thinking on FcRs, their role in immunity to parasites, and immune evasion strategies employed by parasites in their attempt to neutralize the important immune defense mechanisms mediated by these molecules. PMID:11872400

  3. 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

  4. Chemoenzymatic Fc Glycosylation via Engineered Aldehyde Tags

    PubMed Central

    2014-01-01

    Glycoproteins with chemically defined glycosylation sites and structures are important biopharmaceutical targets and critical tools for glycobiology. One approach toward constructing such molecules involves chemical glycosylation of aldehyde-tagged proteins. Here, we report the installation of a genetically encoded aldehyde tag at the internal glycosylation site of the crystallizable fragment (Fc) of IgG1. We replaced the natural Fc N-glycosylation sequon with a five amino-acid sequence that was efficiently converted by recombinant formylglycine generating enzyme in vitro, thereby introducing aldehyde groups for subsequent chemical elaboration. Oxime-linked glycoconjugates were synthesized by conjugating aminooxy N-acetylglucosamine to the modified Fc followed by enzymatic transfer of complex N-glycans from corresponding glycan oxazolines by an EndoS-derived glycosynthase. In this manner we generated specific Fc glycoforms without relying on natural protein glycosylation machineries. PMID:24702330

  5. Selective Harvesting of Marginating-pulmonary Leukocytes.

    PubMed

    Shaashua, Lee; Sorski, Liat; Melamed, Rivka; Ben-Eliyahu, Shamgar

    2016-01-01

    Marginating-pulmonary (MP) leukocytes are leukocytes that adhere to the inner endothelium of the lung capillaries. MP-leukocytes were shown to exhibit unique composition and characteristics compared to leukocytes of other immune compartments. Evidence suggests higher cytotoxicity of natural killer cells, and a distinct pro- and anti-inflammatory profile of the MP-leukocyte population compared to circulating or splenic immunocytes. The method presented herein enables selective harvesting of MP-leukocytes by forced perfusion of the lungs in either mice or rats. In contrast to other methods used to extract lung-leukocytes, such as tissue grinding and biological degradation, this method exclusively yields leukocytes from the lung capillaries, uncontaminated with parenchymal, interstitial, and broncho-alveolar cells. In addition, the perfusion technique better preserves the integrity and the physiological milieu of MP-leukocytes, without inducing physiological responses due to tissue processing. This unique MP leukocyte population is strategically located to identify and react towards abnormal circulating cells, as all circulating malignant cells and infected cells are detained while passing through the lung capillaries, physically interacting with endothelial cells and resident leukocytes,. Thus, selective harvesting of MP-leukocytes and their study under various conditions may advance our understanding of their biological and clinical significance, specifically with respect to controlling circulating aberrant cells and lung-related diseases. PMID:27023665

  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. 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

  8. Leukocyte margination at arteriole shear rate

    PubMed Central

    Takeishi, Naoki; Imai, Yohsuke; Nakaaki, Keita; Yamaguchi, Takami; Ishikawa, Takuji

    2014-01-01

    Abstract We numerically investigated margination of leukocytes at arteriole shear rate in straight circular channels with diameters ranging from 10 to 22 μm. Our results demonstrated that passing motion of RBCs effectively induces leukocyte margination not only in small channels but also in large channels. A longer time is needed for margination to occur in a larger channel, but once a leukocyte has marginated, passing motion of RBCs occurs continuously independent of the channel diameter, and leukocyte margination is sustained for a long duration. We also show that leukocytes rarely approach the wall surface to within a microvillus length at arteriole shear rate. PMID:24907300

  9. Downmodulation of vaccine-induced immunity and protection against the intracellular bacterium Francisella tularensis by the inhibitory receptor FcγRIIB.

    PubMed

    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

  10. 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

  11. A Model of Canine Leukocyte Telomere Dynamics

    PubMed Central

    Benetos, Athanase; Kimura, Masayuki; Labat, Carlos; Buchoff, Gerald M.; Huber, Shell; Labat, Laura; Lu, Xiaobin; Aviv, Abraham

    2011-01-01

    Summary Recent studies have found associations of leukocyte telomere length (TL) with diseases of aging and with longevity. However, it is unknown whether birth leukocyte TL or its age-dependent attrition— the two factors that determine leukocyte TL dynamics— explains these associations, since acquiring this information entails monitoring individuals over their entire life course. We tested in dogs a model of leukocyte TL dynamics, based on the following premises: (i) TL is synchronized among somatic tissues; (ii) TL in skeletal muscle, which is largely post-mitotic, is a measure of TL in early development; (iii) the difference between TL in leukocytes and muscle (ΔLMTL) is the extent of leukocyte TL shortening since early development. Using this model, we observed in 83 dogs (ages 4–42 months) no significant change with age in TLs of skeletal muscle and a shorter TL in leukocytes than in skeletal muscle (P<0.0001). Age explained 43% of the variation in ΔLMTL (P<0.00001) but only 6% of the variation in leukocyte TL (P=0.035) among dogs. Accordingly, muscle TL and ΔLMTL provide the two essential factors of leukocyte TL dynamics in the individual dog. When applied to humans, the partition of the contribution of leukocyte TL during early development versus telomere shortening afterward might provide information about whether the individual’s longevity is calibrated to either one or both factors that define leukocyte TL dynamics. PMID:21917112

  12. Immunogenic and antigenic epitopes of immunoglobulins binding of human monoclonal anti-D antibodies to FcRI on the monocyte-like U937 cell line.

    PubMed

    Walker, M R; Kumpel, B M; Thompson, K; Woof, J M; Burton, D R; Jefferis, R

    1988-01-01

    Seventeen human monoclonal IgG1- or IgG3 anti-D-secreting clones have been examined for their ability to sensitise O+ red cells for Fc-receptor-mediated rosette formation with U937 cells. IgG3 but not IgG1 anti-D antibodies were able to mediate stable rosette formation with unstimulated U937 cells via interaction with the FcRI receptor. Decreasing FcRI density by incubating U937 cells with di-butyryl cAMP almost completely abolished rosette formation, whilst increasing FcRI density by incubating U937 cells with interferon-gamma increased the percentage of cells forming rosettes with IgG3- and IgG1-sensitised red cells. These data suggest that rosette formation between IgG anti-D-sensitised red cells and FcRI-expressing cells is dependent upon the density of IgG3 on the red cell surface, the density of FcRI on the effector cell, multiple FcRI/IgG interactions are required for stable rosette formation and that more FcRI/IgG1 than FcRI/IgG3 interactions are required. PMID:2464239

  13. 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...

  14. 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

  15. The Long Elusive IgM Fc Receptor, FcμR

    PubMed Central

    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

    2014-01-01

    IgM exists as both a monomer on the surface of B cells and a pentamer secreted by plasma cells. Both preimmune “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. PMID:24793544

  16. 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

  17. Murine B-cell stimulatory factor 1 (interleukin 4) increases expression of the Fc receptor for IgE on mouse B cells.

    PubMed Central

    Hudak, S A; Gollnick, S O; Conrad, D H; Kehry, M R

    1987-01-01

    We have studied the activity of mouse B-cell stimulatory factor 1 (interleukin 4, IL-4) on resting splenic B cells and on a B-cell hybridoma. Purified T-cell-derived as well as recombinant IL-4 was shown to increase the expression of the low-affinity Fc receptor for IgE (Fc epsilon R) on a majority of B lymphocytes in a 24-hr culture period. Levels of Fc epsilon R expression increased 2- to 3-fold on splenic B cells and up to 6-fold on a B-cell hybridoma. The effect was inhibited by an anti-IL-4 monoclonal antibody and by mouse gamma-interferon. Other recombinant lymphokines exhibited no effect on either Fc epsilon R expression or the induction by IL-4. The presence of IgE during the stimulation with IL-4 resulted in an additional increase in Fc epsilon R expression. These data and results showing that IgE prevents Fc epsilon R turnover while IL-4 increases the rate of Fc epsilon R synthesis suggest that the mechanisms by which IgE and IL-4 increase Fc epsilon R expression are likely to be different. The starting population of splenic B cells expressed low levels of Fc epsilon R and was relatively uniform in size (small). After greater than 48 hr of culture with IL-4, viable B cells had not undergone DNA synthesis and consisted mainly of larger highly Fc epsilon R-positive cells (23%) and medium-sized Fc epsilon R-positive cells (60%). A possible role for Fc epsilon R in certain B-cell maturation pathways is discussed. Images PMID:2955412

  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. The old but new IgM Fc receptor (FcμR).

    PubMed

    Kubagawa, Hiromi; Kubagawa, Yoshiki; Jones, Dewitt; Nasti, Tahseen H; Walter, Mark R; Honjo, Kazuhito

    2014-01-01

    IgM is the first Ig isotype to appear during phylogeny, ontogeny and the immune response. The importance of both pre-immune "natural" and antigen-induced "immune" IgM antibodies in immune responses to pathogens and self-antigens has been established by studies of mutant mice deficient in IgM secretion. 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 immune protection and regulation of immune responses. Particularly, the role of the Fc receptor for IgM (FcμR) in such effector functions has not been explored until recently. We have identified an authentic FcμR in humans using a functional cloning strategy and subsequently in mice by RT-PCR and describe here its salient features and the immunological consequences of FcμR deficiency in mice. Since the FcμR we cloned was identical to Toso or Fas inhibitory molecule 3 (FAIM3), there have been spirited debates regarding the real function of FcμR/Toso/FAIM3 and we will also comment on this topic. PMID:25116093

  20. 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

  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. PMID:26944929

  3. Pharmacokinetics of Peptide-Fc fusion proteins.

    PubMed

    Wu, Benjamin; Sun, Yu-Nien

    2014-01-01

    Peptide-Fc fusion proteins (or peptibodies) are chimeric proteins generated by fusing a biologically active peptide with the Fc-domain of immunoglobulin G. In this review, we describe recent studies that have evaluated the absorption, distribution, metabolism, and excretion characteristics of peptibodies. Key features of the pharmacokinetics of peptibodies include their extended half-life due to recycling by the neonatal Fc receptor (FcRn), a substantial contribution by renal excretion to total clearance and, for certain peptibodies, target-mediated drug disposition. The prolonged half-life of peptibodies permits less-frequent dose administration compared with small therapeutic peptides, thereby supporting patient convenience and compliance. Hence, a considerable number of peptibodies are currently in preclinical and clinical development. Investigation of the metabolism (biotransformation) of biologics is an evolving area of research: ligand-binding mass spectrometry techniques have been employed for the characterization of the peptibody romiplostim, providing a new approach to evaluation of the degradation products of biologics. Pharmacokinetic/pharmacodynamic modeling and simulation techniques have been used to predict the pharmacokinetics of peptibodies which can inform clinical decision-making, particularly selection of dosing regimens. This integrated review highlights the distinct pharmacokinetic characteristics of peptibodies and their influence on the drug development process for this emerging family of therapeutics. PMID:24285510

  4. 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

  5. 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.

  6. Hydrodynamic Gene Delivery of CC Chemokine Binding Fc Fusion Proteins to Target Acute Vascular Inflammation In Vivo

    PubMed Central

    McNeill, Eileen; Iqbal, Asif J.; White, Gemma E.; Patel, Jyoti; Greaves, David R.; Channon, Keith M.

    2015-01-01

    Blockade of CC chemokines is an attractive yet under utilized therapeutic strategy. We report the in vivo pharmacokinetics of a broad-spectrum vaccinia virus CC chemokine binding protein (35 K) fused to human IgG1 Fc. We demonstrate that the in vivo efficacy of the protein can be interrogated using hydrodynamic gene delivery of a standard mammalian expression plasmid. High plasma levels of the 35 K-Fc protein are maintained for at least 14 days post gene transfer, with the protein still detectable at 5 weeks. We confirm that the protein has biological activity in acute inflammation, causing a significant reduction in monocyte recruitment during zymosan induced peritonitis. The ability of 35 K-Fc to block more complex pathologies is demonstrated using aortic digests to assess angiotensin II mediated leukocyte recruitment to the aorta. Angiotensin II causes upregulation of mCCL2 in the aorta causing the accumulation of CCR2+ cells. Peak monocyte recruitment to the aorta occurs within 3 days and this process is CC chemokine dependent, being significantly reduced by hydrodynamic delivery of 35 K-Fc. PMID:26620767

  7. Isotype-specific immunoregulation; characterization and function of Fc receptors on T-T hybridomas which produce murine IgA-binding factor.

    PubMed

    Kurita, T; Kiyono, H; Komiyama, K; Grossi, C E; Mestecky, J; McGhee, J R

    1986-06-01

    Several methods have been used in the present study to characterize Fc receptors (FcR) expressed on T-T hybridomas derived from mouse Peyer's patch T helper (Th) cell clones that preferentially support IgA responses. These T hybridomas (designated Th HA cells) produce IgA-binding factor (IBF alpha) which regulates antigen-dependent IgA responses. The ultrastructure of Th HA cells and the distribution of Fc alpha R on these cell lines were determined by colloidal gold (CG) immunoelectron microscopy (IEM). When Th HA cells were incubated with purified mouse IgA followed by CG-labeled anti-IgA, an even pattern of CG was distributed on the cell membrane. To ensure that binding occurred through Fc alpha R, Th HA cells were mixed with MOPC 315 IgA anti-DNP, followed by staining with CG-labeled TNP-human serum albumin. This resulted in an identical pattern of gold particle distribution, confirming expression of Fc alpha R on Th HA cells. No Fc mu R or Fc gamma 1R were detectable on Th HA cells by IEM. Immunocytoadherence with TNP-conjugated erythrocytes confirmed that Th HA cells were Fc alpha R+; however, no IgM or IgG rosettes were seen. When these cell lines were analyzed by flow cytometry (FACS) using IgA, IgM, or IgG1 and FITC-labeled anti-H chain-specific antibodies, 55 to 65% of cultured Th HA cells expressed Fc alpha R, and 11 to 18% expressed Fc mu R; however, no Fc gamma 1R was detectable on Th HA cells. The use of ELISA with Th HA cells as antigen confirmed the expression of Fc alpha R and the presence of less Fc mu R on these two cell lines. Solubilized membrane fractions derived from Th HA cells were tested for the presence of FcR by ELISA and for biologic function for support of IgA responses in Peyer's patch B cell cultures. Both Fc alpha R and Fc mu R were detected in fractions derived from Th HA cells. Furthermore, these fractions supported in vitro IgA anti-sheep erythrocyte responses, comparable to those obtained with Th HA cell culture supernatants

  8. 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

  9. 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

  10. 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. PMID:25258391

  11. Disseminated Intravascular Coagulation Induced with Leukocyte Procoagulant

    PubMed Central

    Kociba, Gary J.; Griesemer, Richard A.

    1972-01-01

    The procoagulant activity of rabbit peritoneal leukocytes significantly increased when the leukocytes were incubated in suspension cultures at 37 C for 24 hours. Intravenous infusions of Iysates of 232 × 106 rabbit leukocytes which had been incubated in cultures at 37 C for 24 hours produced disseminated intravascular coagulation and vasculitis involving the pulmonary arteries in normal rabbits. Intraaortic infusions of lysates of 230 × 106 similarly incubated leukocytes produced renal thrombosis and renal cortical necrosis in normal rabbits. These observations suggest that the procoagulant of granulocytic leukocytes could play a role in the generalized Shwartzman reaction and other syndromes of disseminated intravascular coagulation. ImagesFig 3Fig 4Fig 5Fig 6Fig 7Fig 1Fig 2 PMID:5086898

  12. Leukocyte rheology in recent stroke.

    PubMed

    Ernst, E; Matrai, A; Paulsen, F

    1987-01-01

    Eighteen patients with recent ischemic stroke were compared with an equal number of matched controls. Standardized suspensions of red cells as well as of red and white cells were filtered in a new filtration apparatus capable of discriminating between cell deformability and filter occlusion. Results show that red cell deformability, although slightly lower than in controls, is not significantly altered in stroke patients. Filter occlusion, however, was significantly higher in patients when red and white cell suspensions were filtered, but not when red cell suspensions were used, suggesting that white cell filterability is impaired after stroke, which could be due to decreased deformability and/or increased adhesiveness of leukocytes. Slowed white cell passage may also occur in the living microcirculation and may present an obstacle to nutritive flow in exchange vessels, possibly contributing to local ischemia and tissue necrosis after stroke. PMID:3810770

  13. In vitro activation of a transcription factor by gamma interferon requires a membrane-associated tyrosine kinase and is mimicked by vanadate.

    PubMed Central

    Igarashi, K; David, M; Larner, A C; Finbloom, D S

    1993-01-01

    Gamma interferon (IFN-gamma) activates the formation of a DNA-binding protein complex (FcRF gamma) that recognizes the gamma response region (GRR) of the promoter for the human high-affinity Fc gamma receptor. In a membrane-enriched fraction prepared from human peripheral blood monocytes, IFN-gamma activation of FcRF gamma occurred within 1 min and was ATP dependent. Activation of FcRF gamma required a tyrosine kinase activity, and recognition of the GRR sequence by FcRF gamma could be abrogated by treatment with a tyrosine-specific protein phosphatase. Treatment of cells with vanadate alone resulted in the formation of FcRF gamma without the need for IFN-gamma. UV cross-linking and antibody competition experiments demonstrated that the FcRF gamma complex was composed of at least two components: the 91-kDa protein of the IFN-alpha-induced transcription complex ISGF3 and a 43-kDa component that bound directly to the GRR. Therefore, specificity for IFN-induced transcriptional activation of early response genes requires at least two events: (i) ligand-induced activation of membrane-associated protein by tyrosine phosphorylation and (ii) formation of a complex composed of an activated membrane protein(s) and a sequence-specific DNA-binding component. Images PMID:8321205

  14. Characterization of the Rabbit Neonatal Fc Receptor (FcRn) and Analyzing the Immunophenotype of the Transgenic Rabbits That Overexpresses FcRn

    PubMed Central

    Catunda Lemos, Ana Paula; Cervenak, Judit; Bender, Balázs; Hoffmann, Orsolya Ivett; Baranyi, Mária; Kerekes, Andrea; Farkas, Anita; Bősze, 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. PMID:22247762

  15. 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.

  16. 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

  17. Stimulatory effects of ingenols from Euphorbia kansui on the expression of macrophage Fc receptor.

    PubMed

    Matsumoto, T; Cyong, J C; Yamada, H

    1992-06-01

    Immune complex binding to macrophages was enhanced by treatment with an E. kansui extract. Systematic fractionation of the extract led to the characterization of 3-O-(2'E,4'Z-decadienoyl)- and 3-O-(2,3-dimethylbutyryl)-13- O-n-dodecanoyl-13-hydroxyingenol as the active principles. Immune complex binding to macrophages by the action of these compounds increased in a dose-dependent manner. When each ingenol (10 nM) was added to the separated culture medium, the immune complex binding ability of macrophages increased up to 2-fold, respectively. Scatchard analysis showed the enhanced expression of the Fc-receptor for gamma-globulin by the action of each ingenol to macrophages. This Fc-receptor upregulation was dependent on RNA synthesis, suggesting a possible de novo synthesis. PMID:1409980

  18. [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

  19. 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

  20. 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

  1. 21 CFR 864.7660 - Leukocyte alkaline phosphatase test.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Leukocyte alkaline phosphatase test. 864.7660... Leukocyte alkaline phosphatase test. (a) Identification. A leukocyte alkaline phosphatase test is a device used to identify the enzyme leukocyte alkaline phosphatase in neutrophilic granulocytes...

  2. 21 CFR 864.7660 - Leukocyte alkaline phosphatase test.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Leukocyte alkaline phosphatase test. 864.7660... Leukocyte alkaline phosphatase test. (a) Identification. A leukocyte alkaline phosphatase test is a device used to identify the enzyme leukocyte alkaline phosphatase in neutrophilic granulocytes...

  3. 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.

  4. Coagulant Activity of Leukocytes. TISSUE FACTOR ACTIVITY

    PubMed Central

    Niemetz, J.

    1972-01-01

    Peritoneal leukocytes harvested from rabbits which have received two spaced doses of endotoxin have significantly greater (10-fold) coagulant activity than leukocytes from control rabbits. The coagulant activity accelerates the clotting of normal plasma and activates factor X in the presence of factor VII and calcium and is therefore regarded as tissue factor. A total of 40-80 mg tissue factor activity was obtained from the peritoneal cavity of single endotoxin-treated rabbits. In leukocyte subcellular fractions, separated by centrifugation, the specific tissue factor activity sedimented mainly at 14,500 g and above. The procoagulant activity was destroyed after heating for 10 min at 65°C but was preserved at lower temperatures. Polymyxin B, when given with the first dose of endotoxin, reduced both the number of peritoneal leukocytes and their tissue factor activity by two-thirds. When given immediately before the second dose of endotoxin, polymyxin B had no inhibitory effect. PMID:4333021

  5. 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

  6. 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

  7. Ligand Valency Affects Transcytosis, Recycling and Intracellular Trafficking Mediated by the Neonatal Fc Receptor

    PubMed Central

    Tesar, Devin B; Tiangco, Noreen E; Bjorkman, Pamela J

    2006-01-01

    The neonatal Fc receptor (FcRn) transports IgG across epithelial cell barriers to provide maternal antibodies to offspring and serves as a protection receptor by rescuing endocytosed IgG and albumin from lysosomal degradation. Here we describe the generation of polarized Madin–Darby canine kidney (MDCK) cells expressing rat FcRn (rFcRn) to investigate the potential requirement for ligand bivalency in FcRn-mediated transport. The rFcRn-MDCK cells bind, internalize and bidirectionally transcytose the bivalent ligands IgG and Fc across polarized cell monolayers. However, they cannot be used to study FcRn-mediated transport of the monovalent ligand albumin, as we observe no specific binding, internalization or transcytosis of rat albumin. To address whether ligand bivalency is required for transport, the ability of rFcRn to transcytose and recycle wild-type Fc homodimers (wtFc; two FcRn-binding sites) and a heterodimeric Fc (hdFc; one FcRn-binding site) was compared. We show that ligand bivalency is not required for transcytosis or recycling, but that wtFc is transported more efficiently than hdFc, particularly at lower concentrations. We also demonstrate that hdFc and wtFc have different intracellular fates, with more hdFc than wtFc being trafficked to lysosomes and degraded, suggesting a role for avidity effects in FcRn-mediated IgG transport. PMID:17004319

  8. 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

  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. PMID:25488117

  10. 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.

  11. Metabolomics profiling reveals novel markers for leukocyte telomere length.

    PubMed

    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

  12. 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

  13. Structural characterization of anti-inflammatory Immunoglobulin G Fc proteins

    PubMed Central

    Ahmed, Alysia A.; Giddens, John; Pincetic, Andrew; Lomino, Joseph V.; Ravetch, Jeffrey V.; Wang, Lai-Xi; Bjorkman, Pamela J.

    2014-01-01

    Immunoglobulin G (IgG) is a central mediator of host defense due to its ability to recognize and eliminate pathogens. The recognition and effector responses are encoded on distinct regions of IgGs. The diversity of the antigen recognition Fab domains accounts for IgG's ability to bind with high specificity to essentially any antigen. Recent studies have indicated that the Fc effector domain also displays considerable heterogeneity, accounting for its complex effector functions of inflammation, modulation and immune suppression. Therapeutic anti-tumor antibodies, for example, require the pro-inflammatory properties of the IgG Fc to eliminate tumor cells, while the anti-inflammatory activity of Intravenous Immunoglobulin G (IVIG) requires specific Fc glycans for activity. In particular, the anti-inflammatory activity of IVIG is ascribed to a small population of IgGs in which the Asn297-linked complex N-glycans attached to each Fc CH2 domain include terminal α2,6-linked sialic acids. We used chemoenzymatic glycoengineering to prepare fully di-sialylated IgG Fc and solved its crystal structure. Comparison of the structures of asialylated Fc, sialylated Fc, and F241A Fc, a mutant that displays increased glycan sialylation, suggests that increased conformational flexibility of the CH2 domain is associated with the switch from pro- to anti-inflammatory activity of the Fc. PMID:25036289

  14. 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. PMID:15040582

  15. Enhanced Pharmacokinetics of Factor VIIa as a Monomeric Fc Fusion.

    PubMed

    Salas, Joe; Liu, Tongyao; Lu, Qi; Kulman, John D; Ashworth, Tamera; Kistanova, Elena; Moore, Nancy; Pierce, Glenn F; Jiang, Haiyan; Peters, Robert

    2015-05-01

    Recombinant Factor VIIa (rFVIIa) is utilized for on-demand treatment of bleeding episodes in hemophilia patients with neutralizing antibodies (inhibitors) against Factor VIII or Factor IX, but a short half-life in the circulation (~2.5hrs) limits its use in a prophylactic setting. Recombinant FVIIa variants with improved pharmacokinetic properties may enable improved treatment and prevention of bleeding episodes in the inhibitor population. In this study we describe recombinant FVIIaFc (rFVIIaFc), a recombinant Fc-fusion protein generated to utilize the neonatal Fc receptor (FcRn)-mediated recycling pathway that protects immunoglobulin G from catabolism. On the basis of activity, rFVIIaFc exhibited a 5.5-fold extension in terminal half-life in hemophilia A mice compared to rFVIIa. The potency of rFVIIaFc was comparable to that of rFVIIa in thrombin generation assay and ROTEM. In agreement with these data, rFVIIaFc and rFVIIa showed similar acute efficacy at comparable molar doses in the tail clip bleeding model in hemophilia A mice. Taken together, these studies demonstrate enhanced pharmacokinetics and similar hemostatic properties for rFVIIaFc compared to rFVIIa. PMID:25721936

  16. 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.

  17. 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

  18. 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. PMID:26605493

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Leukocyte migration inhibition in nickel dermatitis.

    PubMed

    Mirza, A M; Perera, M G; Maccia, C A; Dziubynskyj, O G; Bernstein, I L

    1975-01-01

    Leukocyte migration inhibitory factor assay was employed as an in vitro diagnostic aid in nickel dermatitis, the second most common contact dermatitis in North America. 15 patch test-positive and 5 patch test-negative patients, all giving a past history suggestive of nickel dermatitis, were investigated. Significant inhibition of leukocyte migration in both groups of patients was obtained only with nickel sulfate-albumin conjugate and not with unconjugated nickel sulfate. Specificity of this system was tested by utilizing an unrelated metallic albumin complex, and no inhibition was found. When patch testing is equivocal or contraindicated, this in vitro technique may be a practical alternative. PMID:1102460

  4. 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. PMID:15485844

  5. Leukocyte Extravasation: An immunoregulatory role for α-L Fucosidase?

    PubMed Central

    Ali, Simi; Jenkins, Yvonne; Kirkley, Maureen; Dagkalis, Athanasios; Manivannan, Ayyakkannu; Crane, Isabel Joan; Kirby, John A

    2009-01-01

    Fucosylated oligosaccharides and glycoconjugates have been implicated in several biological events, including the cell-cell adhesion processes which mediate inflammation. Alpha-L-fucosidase (ALF) is an exoglycosidase which is involved in the hydrolytic degradation of α-L-fucose from glycoconjugates. In this study we investigated the potential role of ALF in regulation of leukocyte migration. Measurement of trans-endothelial migration in response to CCL5 demonstrated that pre-treatment of monocytic cells with ALF reduced migration (p=0.0004) to a greater extent than treatment of the endothelial monolayer (p=0.0374). Treatment with ALF significantly reduced the adhesion of monocytic cells to immobilized P-selectin.Fc. A murine model of experimental autoimmune uveitis was then used to show that treatment of splenic cells with ALF produced an 8.6-fold decrease in rolling and a 3.2-fold decrease in cell migration across the retinal vasculature. Further in vitro studies demonstrated that treatment of monocytes with the chemokines CCL3 or CCL5 increased the level of mRNA encoding ALF; this was accompanied by the detection of significant increases in both the 51kDa and 56kDa components of ALF by Western blotting. Treatment of monocytic cells with ALF for 2h significantly reduced the cell-surface expression of CD31, with a further decrease in expression observed after 5h (p=0.002). Thus, CD31 and fucosylated ligands of P-selectin seem to be the candidates through which ALF mediates its effect in vitro. These data identify a previously unrecognized immunoregulatory role for ALF in late stages of inflammation. PMID:18684930

  6. Registration of FC221 Multigerm Sugarbeet Germplasm with Multiple Disease Resistance.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    FC220’ and ‘FC221’ (PI 651015 and PI 651016) sugarbeet germplasms (Beta vulgaris L.) were released from 05-FC1030-15 (Sp) and 05-FC1030-16 (Sp) seed lots, respectively, and tested under those designations and as 03-FC1030-15 and 03-FC1030-16, respectively. They were developed by the USDA-ARS, at F...

  7. Registration of FC220 Multigerm Sugarbeet Germplasm with Multiple Disease Resistance.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    FC220’ and ‘FC221’ (PI 651015 and PI 651016) sugarbeet germplasms (Beta vulgaris L.) were released from 05-FC1030-15 (Sp) and 05-FC1030-16 (Sp) seed lots, respectively, and tested under those designations and as 03-FC1030-15 and 03-FC1030-16, respectively. They were developed by the USDA-ARS, at F...

  8. 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 ...

  9. 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.

  10. 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.

  11. Oxygen radical production by avian leukocytes.

    PubMed

    Conlon, P; Smith, D; Gowlett, T

    1991-04-01

    Oxygen radical production by heterophils of red-tailed hawks and chickens, and by neutrophils of calves, was evaluated in a chemiluminescence microassay. Leukocytes were isolated by centrifugation of blood in capillary tubes and then challenged with opsonized zymosan in the presence of luminol. Avian heterophils produced significantly fewer oxygen radicals than did bovine neutrophils. PMID:1884301

  12. MICROWAVES, HYPERTHERMIA, AND HUMAN LEUKOCYTE FUNCTION

    EPA Science Inventory

    The objective of this study is to determine whether exposure to microwaves (2450 MHz) affects the function of human leukocytes in the resting state and during antigenic or mitogenic challenge. This publication is a summary report of the construction and calibration of a waveguide...

  13. SAN virtualization study and implementation based on FC switches

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Cao, Mingcui; Luo, Zhixiang

    2005-11-01

    Currently the mainstream technology of SAN is SAN storage virtualization and its implementation. The switch-based storage virtualization embeds the virtualizer in the core of the storage networking fabric in an "intelligent switch" rather than an appliance or a host. This paper describes the SV-FC SAN switch's hardware and software architecture. The main aid of design and implementation the switch is to give a new way to realize FC-SAN storage virtualization. Storage virtualization modules are embedded in the switches firmware. The switch can provide simple and friendly interfaces for users to configure and manage the FC SAN.

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

    PubMed Central

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

    1994-01-01

    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. Images Fig. 4. PMID:7911733

  15. 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

  16. 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.

  17. 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. PMID:27260809

  18. Fc-fusion proteins: new developments and future perspectives

    PubMed Central

    Czajkowsky, Daniel M; Hu, Jun; Shao, Zhifeng; Pleass, Richard J

    2012-01-01

    Since the first description in 1989 of CD4-Fc-fusion antagonists that inhibit human immune deficiency virus entry into T cells, Fc-fusion proteins have been intensely investigated for their effectiveness to curb a range of pathologies, with several notable recent successes coming to market. These promising outcomes have stimulated the development of novel approaches to improve their efficacy and safety, while also broadening their clinical remit to other uses such as vaccines and intravenous immunoglobulin therapy. This increased attention has also led to non-clinical applications of Fc-fusions, such as affinity reagents in microarray devices. Here we discuss recent results and more generally applicable strategies to improve Fc-fusion proteins for each application, with particular attention to the newer, less charted areas. PMID:22837174

  19. 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.

  20. An alternative pathway for fibrinolysis. I. The cleavage of fibrinogen by leukocyte proteases at physiologic pH.

    PubMed Central

    Plow, E F; Edgington, T S

    1975-01-01

    An alternative fibrinolytic system, active at physiological pH, is present in peripheral blood leukocytes. The fibrinolytic proteases localized predominantly in the leukocyte granules are capable of degrading both fibrinogen and fibrin, and plasmin activity does not contribute significantly to this proteolytic event. The specificity of the alternative fibrinolytic proteases for fibrinogen and the characteristics of the derivative cleavage fragments are clearly distinguishable from the classical plasmin system. The high molecular weight derivatives of fibrinogen, generated by the alternative system, under physiological conditions, are larger than the plasmin-generated X fragment, exhibit immunoelectrophoretic mobility comparable to native fibrinogen, and are not coagulable by thrombin. Analysis of the constituent polypeptide chains of the fragments reveals cleavage of the Aalpha, Bbeta, and gamma chains of fibrinogen. The lower molecular weight derivatives of fibrinogen, generated by the alternative system, are structurally distinct from previously described fibrinogen degradation products and exhibit potent anticoagulant activity. This anticoagulant activity can be attributed to interference with normal fibrin polymerization. The proteases of the alternative fibrinolytic systems are actively secreted by leukocytes when stimulated to undergo a nonlytic release reaction. These results provide direct evidence for a fibrinolytic system resident in leukocyte granules that is associated with the leukocyte release reaction and is capable of generating unique fibrinogen cleavage fragments. Images PMID:237938

  1. Nicotinamide phosphoribosyltransferase leukocyte overexpression in Graves' opthalmopathy.

    PubMed

    Sawicka-Gutaj, Nadia; Budny, Bartłomiej; Zybek-Kocik, Ariadna; Sowiński, Jerzy; Ziemnicka, Katarzyna; Waligórska-Stachura, Joanna; Ruchała, Marek

    2016-08-01

    To investigate the role of NAMPT/visfatin in euthyroid patients with Graves' disease without (GD) and with Graves' ophthalmopathy (GO), we analyzed NAMPT leukocyte expression and its serum concentration. This was a single-center, cross-sectional study with consecutive enrollment. In total, 149 patients diagnosed with Graves' disease were enrolled in the study. We excluded subjects with hyper- or hypothyroidism, diabetes mellitus, other autoimmune disorders, active neoplastic disease, and infection. The control group was recruited among healthy volunteers adjusted for age, sex, and BMI with normal thyroid function and negative thyroid antibodies. Serum levels of visfatin, TSH, FT4, FT3, antibodies against TSH receptor (TRAb), antithyroperoxidase antibodies, antithyroglobulin antibodies, fasting glucose, and insulin were measured. NAMPT mRNA leukocyte expression was assessed using RT-qPCR. NAMPT/visfatin serum concentration was higher in GD (n = 44) and GO (n = 49) patients than in the control group (n = 40) (p = 0.0275). NAMPT leukocyte expression was higher in patients with GO (n = 30) than in GD patients (n = 27) and the control group (n = 29) (p < 0.0001). Simple linear regression analysis revealed that NAMPT/visfatin serum concentration was significantly associated with GD (β = 1.5723; p = 0.021). When NAMPT leukocyte expression was used as a dependent variable, simple regression analysis found association with TRAb, fasting insulin level, HOMA-IR, GD, and GO. In the stepwise multiple regression analysis, we confirmed the association between higher serum NAMPT/visfatin level and GD (coefficient = 1.5723; p = 0.0212), and between NAMPT leukocyte expression and GO (coefficient = 2.4619; p = 0.0001) and TRAb (coefficient = 0.08742; p = 0.006). Increased NAMPT leukocyte expression in patients with GO might suggest a presently undefined role in the pathogenesis of GO. PMID:26767650

  2. Neonatal Fc receptor promotes immune complex-mediated glomerular disease.

    PubMed

    Olaru, Florina; Luo, Wentian; Suleiman, Hani; St John, Patricia L; Ge, Linna; Mezo, Adam R; Shaw, Andrey S; Abrahamson, Dale R; Miner, Jeffrey H; Borza, Dorin-Bogdan

    2014-05-01

    The neonatal Fc receptor (FcRn) is a major regulator of IgG and albumin homeostasis systemically and in the kidneys. We investigated the role of FcRn in the development of immune complex-mediated glomerular disease in mice. C57Bl/6 mice immunized with the noncollagenous domain of the α3 chain of type IV collagen (α3NC1) developed albuminuria associated with granular capillary loop deposition of exogenous antigen, mouse IgG, C3 and C5b-9, and podocyte injury. High-resolution imaging showed abundant IgG deposition in the expanded glomerular basement membrane, especially in regions corresponding to subepithelial electron dense deposits. FcRn-null and -humanized mice immunized with α3NC1 developed no albuminuria and had lower levels of serum IgG anti-α3NC1 antibodies and reduced glomerular deposition of IgG, antigen, and complement. Our results show that FcRn promotes the formation of subepithelial immune complexes and subsequent glomerular pathology leading to proteinuria, potentially by maintaining higher serum levels of pathogenic IgG antibodies. Therefore, reducing pathogenic IgG levels by pharmacologic inhibition of FcRn may provide a novel approach for the treatment of immune complex-mediated glomerular diseases. As proof of concept, we showed that a peptide inhibiting the interaction between human FcRn and human IgG accelerated the degradation of human IgG anti-α3NC1 autoantibodies injected into FCRN-humanized mice as effectively as genetic ablation of FcRn, thus preventing the glomerular deposition of immune complexes containing human IgG. PMID:24357670

  3. Neonatal Fc Receptor Promotes Immune Complex–Mediated Glomerular Disease

    PubMed Central

    Olaru, Florina; Luo, Wentian; Suleiman, Hani; St. John, Patricia L.; Ge, Linna; Mezo, Adam R.; Shaw, Andrey S.; Abrahamson, Dale R.; Miner, Jeffrey H.

    2014-01-01

    The neonatal Fc receptor (FcRn) is a major regulator of IgG and albumin homeostasis systemically and in the kidneys. We investigated the role of FcRn in the development of immune complex–mediated glomerular disease in mice. C57Bl/6 mice immunized with the noncollagenous domain of the α3 chain of type IV collagen (α3NC1) developed albuminuria associated with granular capillary loop deposition of exogenous antigen, mouse IgG, C3 and C5b-9, and podocyte injury. High-resolution imaging showed abundant IgG deposition in the expanded glomerular basement membrane, especially in regions corresponding to subepithelial electron dense deposits. FcRn-null and -humanized mice immunized with α3NC1 developed no albuminuria and had lower levels of serum IgG anti-α3NC1 antibodies and reduced glomerular deposition of IgG, antigen, and complement. Our results show that FcRn promotes the formation of subepithelial immune complexes and subsequent glomerular pathology leading to proteinuria, potentially by maintaining higher serum levels of pathogenic IgG antibodies. Therefore, reducing pathogenic IgG levels by pharmacologic inhibition of FcRn may provide a novel approach for the treatment of immune complex–mediated glomerular diseases. As proof of concept, we showed that a peptide inhibiting the interaction between human FcRn and human IgG accelerated the degradation of human IgG anti-α3NC1 autoantibodies injected into FCRN-humanized mice as effectively as genetic ablation of FcRn, thus preventing the glomerular deposition of immune complexes containing human IgG. PMID:24357670

  4. 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.

  5. Nucleate boiling of FC-87/FC-72 zeotropic mixtures on a horizontal copper disc

    NASA Astrophysics Data System (ADS)

    Schlindwein, A. R.; Martin, F. O.; Misale, M.; Passos, J. C.

    2009-05-01

    This paper presents nucleate boiling experimental results, at atmospheric pressure, for heat fluxes q ≤ 40 kW/m2, for FC-87/FC-72 binary mixtures in molar fractions of 0/100, 25/75, 50/50, 75/25, 85/15 and 100/0, at saturation temperatures for pure fluids and bubble points for mixtures. The test section was an upward facing copper disc of 12 mm diameter and 1 mm thickness. The experimental heat transfer coefficient was compared with the correlations of Rohsenow (1952), as reported by Rohsenow et al. (Handbook of heat transfer, McGraw-Hill, New York, 1998), Stephan and Abdelsalam (Int J Heat Mass Transfer 23;73-78, 1978) and Cooper (Int Chem Eng Symp Ser 86:785-792, 1984) for pure fluids and the semi-empirical models of Stephan and Körner (Chem Ing Tech Jahrg 7:409-484, 1969), Thome (J Heat Transfer 104:474-478, 1982), Fujita et al. (1996), as reported by Rohsenow et al. (Handbook of heat transfer, McGraw-Hill, New York, 1998), Fujita and Tsutsui (Int J Heat Mass Transfer 37(1):291-302, 1994) and Calus and Leonidopoulos (Int J Heat Mass Transfer 17:249-256, 1973) for mixtures.

  6. Certolizumab pegol does not bind the neonatal Fc receptor (FcRn): Consequences for FcRn-mediated in vitro transcytosis and ex vivo human placental transfer.

    PubMed

    Porter, Charlene; Armstrong-Fisher, Sylvia; Kopotsha, Tim; Smith, Bryan; Baker, Terry; Kevorkian, Lara; Nesbitt, Andrew

    2016-08-01

    Antibodies to tumor necrosis factor (anti-TNF) are used to treat inflammatory diseases, which often affect women of childbearing age. The active transfer of these antibodies across the placenta by binding of the Fc-region to the neonatal Fc receptor (FcRn) may result in adverse fetal or neonatal effects. In contrast to other anti-TNFs, certolizumab pegol lacks an Fc-region. The objective of this study was to determine whether the structure of certolizumab pegol limits active placental transfer. Binding affinities of certolizumab pegol, infliximab, adalimumab and etanercept to human FcRn and FcRn-mediated transcytosis were determined using in vitro assays. Human placentas were perfused ex vivo to measure transfer of certolizumab pegol and positive control anti-D IgG from the maternal to fetal circulation. FcRn binding affinity (KD) was 132nM, 225nM and 1500nM for infliximab, adalimumab and etanercept, respectively. There was no measurable certolizumab pegol binding affinity, similar to that of the negative control. FcRn-mediated transcytosis across a cell layer (mean±SD; n=3) was 249.6±25.0 (infliximab), 159.0±20.2 (adalimumab) and 81.3±13.1ng/mL (etanercept). Certolizumab pegol transcytosis (3.2±3.4ng/mL) was less than the negative control antibody (5.9±4.6ng/mL). No measurable transfer of certolizumab pegol from the maternal to the fetal circulation was observed in 5 out of 6 placentas that demonstrated positive-control IgG transport in the ex vivo perfusion model. Together these results support the hypothesis that the unique structure of certolizumab pegol limits its transfer through the placenta to the fetus and may be responsible for previously reported differences in transfer of other anti-TNFs from mother to fetus. PMID:27123565

  7. Human FcγRII cytoplasmic domains differentially influence antibody-mediated dengue virus infection.

    PubMed

    Boonnak, Kobporn; Slike, Bonnie M; Donofrio, Gina C; Marovich, Mary A

    2013-06-01

    Ab-dependent enhancement (ADE) of dengue virus (DENV) infection is mediated through the interaction of viral immune complexes with FcγRs, with notable efficiency of FcγRII. Most human dengue target cells coexpress activating (FcγRIIa) and inhibitory (FcγRIIb) isoforms, but their relative roles in ADE are not well understood. We studied the effects of FcγRIIa and FcγRIIb by transfecting cells to express each individual receptor isoform or through coexpression of both isoforms. We showed that although both isoforms similarly bind dengue-immune complexes, FcγRIIa efficiently internalized virus leading to productive cellular infection, unlike FcγRIIb. We next focused on the main discriminating feature of these isoforms: their distinct intracytoplasmic tails (FcγRIIa with an immunoreceptor tyrosine-based activation motif [ITAM] and FcγRIIb with an immunoreceptor tyrosine-based inhibitory motif [ITIM]). We engineered cells to express "swapped" versions of their FcγRII by switching the cytoplasmic tails containing the ITAM/ITIM motifs, leaving the remainder of the receptor intact. Our data show that both FcγRIIa and FcγRIIb comparably bind dengue immune complexes. However, wild type FcγRIIa facilitates DENV entry by virtue of the ITAM motif, whereas the swapped version FcγRIIa-ITIM significantly inhibited ADE. Similarly, replacing the inhibitory motif in FcγRIIb with an ITAM (FcγRIIb-ITAM) reconstituted ADE capacity to levels of the wild type activating counterpart, FcγRIIa. Our data suggest that FcγRIIa and FcγRIIb isoforms, as the most abundantly distributed class II Fcγ receptors, differentially influence Ab-mediated DENV infection under ADE conditions both at the level of cellular infection and viral production. PMID:23616574

  8. Human FcγRII Cytoplasmic Domains Differentially Influence Antibody-Mediated Dengue Virus Infection

    PubMed Central

    Boonnak, Kobporn; Slike, Bonnie M.; Donofrio, Gina C.

    2013-01-01

    Ab-dependent enhancement (ADE) of dengue virus (DENV) infection is mediated through the interaction of viral immune complexes with FcγRs, with notable efficiency of FcγRII. Most human dengue target cells coexpress activating (FcγRIIa) and inhibitory (FcγRIIb) isoforms, but their relative roles in ADE are not well understood. We studied the effects of FcγRIIa and FcγRIIb by transfecting cells to express each individual receptor isoform or through coexpression of both isoforms. We showed that although both isoforms similarly bind dengue-immune complexes, FcγRIIa efficiently internalized virus leading to productive cellular infection, unlike FcγRIIb. We next focused on the main discriminating feature of these isoforms: their distinct intracytoplasmic tails (FcγRIIa with an immunoreceptor tyrosine-based activation motif [ITAM] and FcγRIIb with an immunoreceptor tyrosine-based inhibitory motif [ITIM]). We engineered cells to express “swapped” versions of their FcγRII by switching the cytoplasmic tails containing the ITAM/ITIM motifs, leaving the remainder of the receptor intact. Our data show that both FcγRIIa and FcγRIIb comparably bind dengue immune complexes. However, wild type FcγRIIa facilitates DENV entry by virtue of the ITAM motif, whereas the swapped version FcγRIIa-ITIM significantly inhibited ADE. Similarly, replacing the inhibitory motif in FcγRIIb with an ITAM (FcγRIIb-ITAM) reconstituted ADE capacity to levels of the wild type activating counterpart, FcγRIIa. Our data suggest that FcγRIIa and FcγRIIb isoforms, as the most abundantly distributed class II Fcγ receptors, differentially influence Ab-mediated DENV infection under ADE conditions both at the level of cellular infection and viral production. PMID:23616574

  9. 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.

  10. Getting Leukocytes to the Site of Inflammation

    PubMed Central

    Muller, W. A.

    2013-01-01

    There is no “response” in either the innate or adaptive immune response unless leukocytes cross blood vessels. They do this through the process of diapedesis, in which the leukocyte moves in ameboid fashion through tightly apposed endothelial borders (paracellular transmigration) and in some cases through the endothelial cell itself (transcellular migration). This review summarizes the steps leading up to diapedesis, then focuses on the molecules and mechanisms responsible for transendothelial migration. Surprisingly, many of the same molecules and mechanisms that regulate paracellular migration also control transcellular migration, including a major role for membrane from the recently described lateral border recycling compartment. A hypothesis that integrates the various known mechanisms of transmigration is proposed. PMID:23345459

  11. 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.

  12. 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

  13. Computational modeling of leukocyte adhesion cascade (LAC)

    NASA Astrophysics Data System (ADS)

    Sarkar, Kausik

    2005-11-01

    In response to an inflammation in the body, leukocytes (white blood cell) interact with the endothelium (interior wall of blood vessel) through a series of steps--capture, rolling, adhesion and transmigration--critical for proper functioning of the immune system. We are numerically simulating this process using a Front-tracking finite-difference method. The viscoelastcity of the cell membrane, cytoplasm and nucleus are incorporated and allowed to change with time in response to the cell surface molecular chemistry. The molecular level forces due to specific ligand-receptor interactions are accounted for by stochastic spring-peeling model. Even though leukocyte rolling has been investigated through various models, the transitioning through subsequent steps, specifically firm adhesion and transmigration through endothelial layer, has not been modeled. The change of viscoelastic properties due to the leukocyte activation is observed to play a critical role in mediating the transition from rolling to transmigration. We will provide details of our approach and discuss preliminary results.

  14. 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

  15. 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. PMID:20555360

  16. 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.

  17. 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. PMID:26325284

  18. 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

  19. 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

  20. 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

  1. Registration of FC723 and FC723 CMS Monogerm Sugarbeet Germplasm Resistant to Rhizoctonia Root Rot and moderately Resistant to Cercospora Leaf Spot.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugarbeet (Beta vulgaris L.) germplasms FC723 and FC723CMS (Reg. nos. GP-GP-, PI 639917 and PI 639918, respectively) were developed by the USDA-ARS, at Fort Collins, Colorado, in cooperation with the Beet Sugar Development Foundation, Denver, CO. FC723 has good resistance to root-rotting strains (A...

  2. Production of tumor necrosis factor alpha in human leukocytes stimulated by Cryptococcus neoformans.

    PubMed Central

    Levitz, S M; Tabuni, A; Kornfeld, H; Reardon, C C; Golenbock, D T

    1994-01-01

    Tumor necrosis factor alpha (TNF-alpha) is a key mediator of inflammation and may promote human immunodeficiency virus replication in latently infected cells. Since cryptococcosis often is associated with aberrations in the host inflammatory response and occurs preferentially in persons with AIDS, we defined the conditions under which human leukocytes produce TNF-alpha when stimulated by Cryptococcus neoformans. Peripheral blood mononuclear cells (PBMC) produced comparable amounts of TNF-alpha following stimulation with C. neoformans and lipopolysaccharide. Detectable TNF-alpha release in response to C. neoformans occurred only when fungi with small-sized capsules were used and complement-sufficient serum was added. Fractionation of PBMC established that monocytes were the predominant source of TNF-alpha. TNF-alpha gene expression and release occurred significantly later in PBMC stimulated with C. neoformans than in PBMC stimulated with LPS. C. neoformans was also a potent inducer of TNF-alpha from freshly isolated bronchoalveolar macrophages (BAM). Upon in vitro culture, BAM and monocytes bound greater numbers of fungal cells, yet their capacity to produce TNF-alpha following cryptococcal stimulation declined by 74 to 100%. However, this decline was reversed if the BAM and monocytes were cultured with gamma interferon. These data establish that C. neoformans can potently stimulate TNF-alpha release from human leukocytes. However, several variables profoundly affected the amount of TNF-alpha released, including the type of leukocyte and its state of activation, the size of the cryptococcal capsule, and the availability of opsonins. PMID:8168965

  3. 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.

  4. 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.

  5. Cervical leukocytes and spontaneous preterm birth

    PubMed Central

    Hunter, Patricia J.; Sheikh, Sairah; David, Anna L.; Peebles, Donald M.; Klein, Nigel

    2016-01-01

    The objective was to characterise cervical leukocyte populations and inflammatory mediators associated with term and recurrent spontaneous preterm birth (SPTB) in pregnant women with a history of SPTB. A prospective observational study was undertaken on 120 women with a history of SPTB. A cytobrush was used to sample cells from the cervix at 12–25 weeks’ gestation. Cells were enumerated and characterised by flow cytometry. Cytokines and chemokines were also measured. Participants were then grouped according to delivery at term (>36 + 6 weeks), late SPTB (34–36 + 6 weeks) or early SPTB (<34 weeks). Differences in leukocyte sub-populations, cytokine and chemokine levels were compared with outcome. Cervical leukocytes comprised up to 60% of the host-derived cells. Most of these (90–100%) were polymorphonuclear cells (PMN). Most of the remaining cells were mucosal macrophages expressing CD68 and CD103 in addition to markers shared with blood-borne monocytes. Failure to detect cervical macrophages in at least 250,000 cervical epithelial cells was a feature of women who experienced early SPTB (6 out of 6 cases, 95% CI 61–100%) compared with 34% (30 out of 88 cases, 95% CI 25–43%, P < 0.001) of women delivering after 34 weeks. CCL2 (MCP-1) was also low in SPTB before 34 weeks and levels above 75 ng/g and/or the presence of macrophages increased the specificity for birth after 34 weeks from 66% to 82% (55 out of 67 cases, 95% CI 73–91%). Absence of cervical macrophages and low CCL2 may be features of pregnancies at risk of early SPTB. PMID:26637953

  6. Imaging of Leukocyte Trafficking in Alzheimer's Disease.

    PubMed

    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

  7. A role for leukocyte-endothelial adhesion mechanisms in epilepsy

    PubMed Central

    Fabene, Paolo F.; Mora, Graciela Navarro; Martinello, Marianna; Rossi, Barbara; Merigo, Flavia; Ottoboni, Linda; Bach, Simona; Angiari, Stefano; Benati, Donatella; Chakir, Asmaa; Zanetti, Lara; Schio, Federica; Osculati, Antonio; Marzola, Pasquina; Nicolato, Elena; Homeister, Jonathon W.; Xia, Lijun; Lowe, John B.; McEver, Rodger P.; Osculati, Francesco; Sbarbati, Andrea; Butcher, Eugene C.; Constantin, Gabriela

    2009-01-01

    The mechanisms involved in the pathogenesis of epilepsy, a chronic neurological disorder that affects approximately 1 percent of the world population, are not well understood1–3. Using a mouse model of epilepsy, we show that seizures induce elevated expression of vascular cell adhesion molecules and enhanced leukocyte rolling and arrest in brain vessels mediated by the leukocyte mucin P-selectin glycoprotein ligand-1 (PSGL-1) and leukocyte integrins α4β1 and αLβ2. Inhibition of leukocyte-vascular interactions either with blocking antibodies, or in mice genetically deficient in functional PSGL-1, dramatically reduced seizures. Treatment with blocking antibodies following acute seizures prevented the development of epilepsy. Neutrophil depletion also inhibited acute seizure induction and chronic spontaneous recurrent seizures. Blood-brain barrier (BBB) leakage, which is known to enhance neuronal excitability, was induced by acute seizure activity but was prevented by blockade of leukocyte-vascular adhesion, suggesting a pathogenetic link between leukocyte-vascular interactions, BBB damage and seizure generation. Consistent with potential leukocyte involvement in the human, leukocytes were more abundant in brains of epileptics than of controls. Our results suggest leukocyte-endothelial interaction as a potential target for the prevention and treatment of epilepsy. PMID:19029985

  8. The role of Fc receptors in HIV prevention and therapy.

    PubMed

    Boesch, Austin W; Brown, Eric P; Ackerman, Margaret E

    2015-11-01

    Over the past decade, a wealth of experimental evidence has accumulated supporting the importance of Fc receptor (FcR) ligation in antibody-mediated pathology and protection in many disease states. Here we present the diverse evidence base that has accumulated as to the importance of antibody effector functions in the setting of HIV prevention and therapy, including clinical correlates, genetic associations, viral evasion strategies, and a rapidly growing number of compelling animal model experiments. Collectively, this work identifies antibody interactions with FcR as important to both therapeutic and prophylactic strategies involving both passive and active immunity. These findings mirror those in other fields as investigators continue to work toward identifying the right antibodies and the right effectors to be present at the right sites at the right time. PMID:26497529

  9. 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.

  10. Fc receptor like 3 in Chinese patients of Han nationality with Guillain-Barré syndrome.

    PubMed

    Sang, Daoqian; Chen, Qiming; Liu, Xiaolin; Qu, Hongdang; Wei, Daoxiang; Yin, Liang; Zhang, Lina

    2012-05-15

    Fc receptor like 3 gene (FcRL3) has been associated with some autoimmune diseases. Here, its role in Guillain-Barré syndrome (GBS) was evaluated by studying nine FcRL3 gene SNPs in a Chinese cohort of GBS patients. The frequencies of FcRL3-3-169C, FcRL3-6 intron3A, and FcRL3-8 exon15G alleles were significantly increased in GBS patients compared with healthy controls. The frequency of FcRL3-1→9 CCTGGAGAA haplotype was significantly increased, and the frequencies of FcRL3-1→9 CCTACAAAA,CCCACGAAA, and CCTGCGGAA haplotypes were significantly decreased compared with healthy controls. These results suggest that FcRL3 is associated with GBS incidence. PMID:22458979

  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. The impact of FcγRIIa and FcγRIIIa gene polymorphisms on responses to RCHOP chemotherapy in diffuse large B-cell lymphoma patients

    PubMed Central

    ROŽMAN, SAMO; NOVAKOVIĆ, SRDJAN; GRABNAR, IZTOK; CERKOVNIK, PETRA; NOVAKOVIĆ, BARBARA JEZERŠEK

    2016-01-01

    Rituximab is a monoclonal antibody routinely used in the treatment of B-cell non-Hodgkin lymphomas. It mediates antibody-dependent cellular cytotoxicity of B lymphocytes by bridging them with Fcγ receptors (FcγR) on effector cells. Several polymorphisms in the FcγR genes have been identified to influence rituximab binding to FcγR, thus altering its antitumor effect in indolent lymphomas. In the present study, the impact of FcγRIIa and FcγRIIIa polymorphisms on the survival and response to immunochemotherapy consisting of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone was evaluated in diffuse large B-cell lymphoma (DLBCL) patients. A total of 29 Slovenian DLBCL patients were studied. Genotyping was conducted for FcγRIIa-27, FcγRIIa-131, FcγRIIIa-48 and FcγRIIIa-158 polymorphisms. The median follow-up time was 29.7 months (range, 9.7–45.4 months). No significant impact of the genotypes was observed on the treatment response, progression-free or overall survival of DLBCL patients. There was a non-significant trend of an improved response to chemotherapy without additional irradiation in patients homozygous for Val at FCγIIIa-158 compared to Phe carriers. The findings of the present study indicate that FcγR polymorphisms have no influence on the survival of DLBCL patients. PMID:27123112

  13. Factors affecting leukocyte count in healthy adults.

    PubMed

    Carel, R S; Eviatar, J

    1985-09-01

    The relationships between white blood cell (WBC) count, smoking, and other health variables were determined among 35,000 apparently healthy men and women. The effect of smoking on the WBC count was greater than that of all other variables. The leukocyte level and the variance in WBC count values increased with increased smoking intensity. The relationship between smoking intensity and leukocyte level is expressed quantitatively by the following regression equation: WBC (10(3)/mm3) = 7.1 + 0.05(SM), where SM has seven values according to the smoking level. Multiple regression analysis with additional variables other than smoking did not much improve the predictive value of the equation. The effect of smoking on WBC count could be only partially explained by an inflammatory process, e.g., chronic bronchitis. Relationships of statistical significance (but mostly with r values of less than 0.10) were found between WBC count and the following variables: hemoglobin, heart rate, weight (or Quetelet index), cholesterol, uric acid, creatinine, sex, ethnic origin, systolic blood pressure, height, blood sugar, and diastolic blood pressure. The normal WBC count range for smokers differs from that of nonsmokers and is shifted to the right according to the smoking level. This may have both a diagnostic and prognostic significance in different clinical settings. PMID:4070192

  14. 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

  15. Quantitative Analysis of Human Neonatal Fc Receptor (FcRn) Tissue Expression in Transgenic Mice by Online Peptide Immuno-Affinity LC-HRMS.

    PubMed

    Fan, Yao-Yun; Neubert, Hendrik

    2016-04-19

    Neonatal Fc receptor (FcRn) is the homeostatic receptor responsible for the long half-life of endogenous IgG by protecting it from lysosomal degradation. Understanding systemic FcRn tissue expression is important to predict and design the half-life of therapeutic antibodies and Fc-coupled biotherapeutics. To this end, we measured human FcRn (hFcRn) tissue expression in Tg32, a human FcRn knock-in transgenic mouse model, for which a strong correlation of drug clearance to humans has been demonstrated. Building an hFcRn tissue expression profile in Tg32 was enabled by the development of a tissue preparation procedure composed of bead-based protein extraction and protein precipitation using acetone followed by pellet digestion with trypsin. Digests were then loaded onto an online peptide immuno-affinity flow configuration hyphenated with reversed phase nanoflow chromatography and coupled with high resolution mass spectrometry to quantify hFcRn derived peptides. The workflow allowed bypassing some of the challenges typically associated with membrane protein analysis. We demonstrated acceptable precision and bias for measuring hFcRn in tissue matrices, typically within 20% coefficient of variation and relative error. We also report hFcRn expression in several Tg32 tissues. We anticipate that establishing a quantitative approach for hFcRn in tissues will enable the systematic measurement of hFcRn concentrations to further increase the accuracy of physiologically based pharmacokinetic (PBPK) models for PK prediction of Fc-containing biotherapeutics. This is anticipated to improve the translation of pharmacokinetic data from preclinical model systems to humans. PMID:27012525

  16. Spontaneous expression of a low affinity Fc receptor for IgA (Fc alpha R) on human B cell lines.

    PubMed Central

    Millet, I; Briere, F; Vincent, C; Rousset, F; Andreoni, C; De Vries, J E; Revillard, J P

    1989-01-01

    Expression of receptors for IgA (Fc alpha Rs) was investigated on a panel of 35 human B cell lines by labelling with human secretory IgA (0.5 mg/ml) and flow cytometry analysis after staining with fluoresceinated goat anti-human secretory component and/or anti-alpha chain F(ab')2 fragments. Receptors for IgA could be demonstrated on one out of nine Burkitt's lymphoma cell lines, three out of five myeloma cell lines and five out of 21 lymphoblastoid cell lines. The percentage of Fc alpha R-positive cells within the same B cell line varied upon repeated examination. Human dimeric IgA1 lambda myeloma protein revealed the same number of IgA receptor positive cells as did secretory IgA, whereas monomeric IgA did not bind to Fc alpha R. Detection of Fc alpha R was not inhibited when the tests were carried out in the presence of human dimeric IgG, IgM, asialo-orosomucoid, and secretory component but it was abrogated by pre-treatment of the cells with trypsin. The binding characteristics of Fc alpha Rs were studied on the myeloma cell line Esteve, using 125I-labelled human dimeric IgA and secretory IgA. The binding was dose-dependent with rapid kinetics and specific inhibition by unlabelled secretory IgA. Scatchard plot analysis resulted in an equilibrium constant K ranging from 3.2 to 4.7 x 10(6) M/l. No correlation was observed between Fc alpha R expression and differentiation stage, monoclonality, polyclonality of the cell lines, or Ig class produced by the B cells. PMID:2788048

  17. 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...

  18. 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

  19. Identification of a family of Fc receptor homologs with preferential B cell expression

    PubMed Central

    Davis, Randall S.; Wang, Yui-Hsi; Kubagawa, Hiromi; Cooper, Max D.

    2001-01-01

    Investigation of human genome sequences with a consensus sequence derived from receptors for the Fc region of Igs (FcR) led to the identification of a subfamily of five Ig superfamily members that we term the Fc receptor homologs (FcRHs). The closely linked FcRH genes are located in a chromosome 1q21 region in the midst of previously recognized FcR genes. This report focuses on the FcRH1, FcRH2, and FcRH3 members of this gene family. Their cDNAs encode type I transmembrane glycoproteins with 3–6 Ig-like extracellular domains and cytoplasmic domains containing consensus immunoreceptor tyrosine-based activating and/or inhibitory signaling motifs. The five FcRH genes are structurally related, and their protein products share 28–60% extracellular identity with each other. They also share 15–31% identity with their closest FcR relatives. The FcRH genes are expressed primarily, although not exclusively, by mature B lineage cells. Their conserved structural features, patterns of cellular expression, and the inhibitory and activating signaling potential of their transmembrane protein products suggest that the members of this FcRH multigene family may serve important regulatory roles in normal and neoplastic B cell development. PMID:11493702

  20. 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.

  1. Alteration of rat polymorphonuclear leukocyte function after thermal injury.

    PubMed

    Gruber, D F; D'Alesandro, M M

    1989-01-01

    One portion of host defense to bacterial challenge(s) involves the activation and infiltration of endogenous polymorphonuclear leukocytes. Thermal injuries are frequently associated with immunologic abnormalities including alterations of polymorphonuclear leukocyte-associated nonspecific resistance. We examined isolated peripheral rat polymorphonuclear leukocytes for alterations in membrane potential, oxidative capability, and locomotor function after the experimental application of 20% full-thickness body surface area thermal injury. Thermal injury resulted in significant reductions of peripheral red blood cell concentration(s) and increases in leukocyte and platelet concentrations for 42 days after injury. In addition to the quantitative changes, polymorphonuclear leukocytes also demonstrated altered qualitative functions. Compared with phorbol myristate acetate-induced activation of normal cells, polymorphonuclear leukocyte membranes from thermal-injured animals were electrophysiologically less responsive for 3 weeks after injury. The ability of polymorphonuclear leukocytes to produce intracellular H2O2, a measure of oxidative function, was also significantly decreased for 7 days after injury. The paradox in this paradigm of thermal injury was the demonstration of peripheral polymorphonuclear leukocyte quantitative increases with concurrent significant qualitative impairment. Qualitative lesions included altered states of membrane depolarization and depressed oxidative capability that may individually, or collectively, reduce nonspecific immune capabilities of the host to levels that are inadequate to combat infection. PMID:2793916

  2. [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

  3. 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... peroxidase test. (a) Identification. A leukocyte peroxidase test is a device used to distinguish certain... peroxidase activity as evidenced by staining. The results of this test are used in the differential...

  4. 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... peroxidase test. (a) Identification. A leukocyte peroxidase test is a device used to distinguish certain... peroxidase activity as evidenced by staining. The results of this test are used in the differential...

  5. 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... peroxidase test. (a) Identification. A leukocyte peroxidase test is a device used to distinguish certain... peroxidase activity as evidenced by staining. The results of this test are used in the differential...

  6. 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... peroxidase test. (a) Identification. A leukocyte peroxidase test is a device used to distinguish certain... peroxidase activity as evidenced by staining. The results of this test are used in the differential...

  7. 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... peroxidase test. (a) Identification. A leukocyte peroxidase test is a device used to distinguish certain... peroxidase activity as evidenced by staining. The results of this test are used in the differential...

  8. 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

  9. Degradation of thyroid hormones by phagocytosing human leukocytes.

    PubMed

    Klebanoff, S J; Green, W L

    1973-01-01

    Thyroxine (T(4)) and triiodothyronine (T(9)) are rapidly degraded by a purified preparation of myeloperoxidase (MPO) and H(2)O(2) with the formation of iodide and material which remains at the origin on paper chromatography. Deiodination by MPO and H(2)O(2) occurs more readily at pH 7.0 than at pH 5.0 in contrast to iodination by this system which is known to occur more readily at pH 5.0 than at pH 7.0. Degradation is inhibited by azide, cyanide, ascorbic acid, and propylthiouracil. Methimazole stimulates deiodination by MPO and H(2)O(2) but inhibits this reaction when MPO is replaced by lactoperoxidase or horseradish peroxidase.Intact human leukocytes, in the resting state, degrade T(4) and T(3) slowly: degradation, however, is increased markedly during phagocytosis of preopsonized particles. Serum inhibits this reaction. T(3) can be detected as a minor product of T(4) degradation. Proteolytic digestion of the reaction products increases the recovery of monoiodotyrosine. The fixation of iodine in the cytoplasm of leukocytes which contain ingested bacteria was detected radioautographically. Chronic granulomatous disease leukocytes, which are deficient in H(2)O(2) formation, degrade T(4) and T(3) poorly during phagocytosis. MPO-deficient leukocytes degrade the thyroid hormones at a slower rate than do normal leukocytes although considerable degradation is still observed. Azide, cyanide, ascorbic acid, and propylthiouracil which inhibit certain peroxidasecatalyzed reactions inhibit degradation by normal leukocytes; however, inhibition is incomplete. Formation of iodinated origin material is inhibited to a greater degree by azide, cyanide, and propylthiouracil than is deiodination. Methimazole inhibits the formation of iodinated origin material by both normal and MPO-deficient leukocytes. However, deiodination by normal leukocytes is stimulated and that of MPO-deficient leukocytes is unaffected by methimazole. Hypoxia inhibits the degradation of T(4) and T(3) by

  10. [Polar coordinates representation based leukocyte segmentation of microscopic cell images].

    PubMed

    Gu, Guanghua; Cui, Dong; Hao, Lianwang

    2010-12-01

    We propose an algorithm for segmentation of the overlapped leukocyte in the microscopic cell image. The histogram of the saturation channel in the cell image is smoothed to obtain the meaningful global valley point by the fingerprint smoothing method, and then the nucleus can be segmented. A circular region, containing the entire regions of the leukocyte, is marked off according to the equivalent sectional radius of the nucleus. Then, the edge of the overlapped leukocyte is represented by polar coordinates. The overlapped region by the change of the polar angle of the edge pixels is determined, and the closed edge of the leukocyte integrating the gradient information of the overlapped region is reconstructed. Finally, the leukocyte is exactly extracted. The experimental results show that our method has good performance in terms of recall ratio, precision ratio and pixel error ratio. PMID:21374971

  11. Cannabinoid-receptor expression in human leukocytes.

    PubMed

    Bouaboula, M; Rinaldi, M; Carayon, P; Carillon, C; Delpech, B; Shire, D; Le Fur, G; Casellas, P

    1993-05-15

    Marijuana and many of its constituent cannabinoids influence the central nervous system (CNS), probably through the cannabinoid receptor, which has recently been cloned in rat and human. While numerous reports have also described effects of cannabinoids on the immune system, the observation of both mRNA and cannabinoid receptor has hitherto been exclusively confined to the brain, a reported detection in the testis being the sole example of its presence at the periphery. Here we report the expression of the cannabinoid receptor on human immune tissues using a highly sensitive polymerase-chain-reaction-based method for mRNA quantification. We show that, although present in a much lower abundance than in brain, cannabinoid receptor transcripts are found in human spleen, tonsils and peripheral blood leukocytes. The distribution pattern displays important variations of the mRNA level for the cannabinoid receptor among the main human blood cell subpopulations. The rank order of mRNA levels in these cells is B cells > natural killer cells > or = polymorphonuclear neutrophils > or = T8 cells > monocytes > T4 cells. Cannabinoid-receptor mRNA, which is also found in monocytic, as well as T and B leukemia cell lines but not in Jurkat cells, presents a great diversity of expression on these cells as well, B-cell lines expressing a much higher level than T-cell lines. The cannabinoid receptor PCR products from leukocytes and brain are identical both in size and sequence suggesting a strong similarity between central and peripheral cannabinoid receptors. The expression of this receptor was demonstrated on membranes of the myelomonocytic U937 cells using the synthetic cannabinoid [3H]CP-55940 as ligand. The Kd determined from Scatchard analysis was 0.1 nM and the Bmax for membranes was 525 fmol/mg protein. The demonstration of cannabinoid-receptor expression at both mRNA and protein levels on human leukocytes provides a molecular basis for cannabinoid action on these cells. PMID

  12. 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

  13. Margination of leukocytes in blood flow through small tubes.

    PubMed

    Goldsmith, H L; Spain, S

    1984-03-01

    Leukocyte margination in the vessels of the microcirculation has been attributed to a flow-dependent interaction with red cells. To determine the extent of this effect, experiments with human blood were done in 100- to 180-micron tubes to detect changes in cell distribution as a function of hematocrit and flow rate. Using a flow visualization technique, the leukocyte concentration distribution was determined in 45% ghost cell suspensions. Migration of cells toward the wall was observed at centerline velocities greater than 1 mm sec-1 and increased with increasing flow rate. The effect was probably due to a more rapid inward migration of ghosts than leukocytes because of fluid inertia and cell density differences. Experiments were therefore carried out in whole blood at hematocrits from 20 to 60%, measuring the number concentration of leukocytes and erythrocytes within the tube, nt, and comparing it to that in the infusing reservoir, no, (Fahraeus effect). At mean tube shear rates G less than 100 sec-1, nt/no less than 1 for both leukocytes and erythrocytes showing net migration of cells away from the wall, although at nearly all hematocrits there was an enrichment of leukocytes relative to erythrocytes in the tubes. At G less than 50 sec-1, nt/no remained less than 1 for erythrocytes but increased to greater than 1 for leukocytes showing migration toward the wall, the increase being greatest at 20% hematocrit in the 100-micron tubes. The nature of the effect was revealed by cine films which showed that, as the flow rate decreased, erythrocytes formed rouleaux which migrated inward creating a core and displacing leukocytes to the periphery. In control experiments using washed blood cells in phosphate buffer-albumin, nt/no less than 1 for both leukocytes and erythrocytes at all G and hematocrits, and leukocytes were now distributed. Cine films of washed blood confirmed that, in the absence of rouleaux, no significant inward migration of erythrocytes occurred. PMID

  14. Factors influencing human leukocyte adherence in vitro.

    PubMed

    Stepniewicz, W; Tchórzewski, H; Luciak, M

    1983-01-01

    Studies were performed on factors influencing leucocyte adherence in vitro. Blood condensation was found to increase leukocyte adherence. Addition of heparin, dextran or ethanol caused a significant reduction of white blood cell count in blood samples in comparison with blood mixed with sodium EDTA or ACD solution. This suggests the existence of two granulocyte subpopulations; viz, rapidly adhering and slowly adhering. Heparin enhanced granulocyte adherence, while dextran and ethanol decreased it. Five-day storage of ACD blood led to a decrease in granulocyte adherence, while addition of heparin or histamine to ACD blood prevented this change to occur. The glucose concentration of 1,000 mg/dl augmented granulocyte adherence, while higher glucose concentrations induced its progressive fall below the control values. There was no significant change of lymphocyte adherence during the experiments. PMID:6194070

  15. [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

  16. Leukocytic oxygen activation and microbicidal oxidative toxins.

    PubMed

    Hurst, J K; Barrette, W C

    1989-01-01

    Following a brief introduction of cellular response to stimulation comprising leukocyte activation, three major areas are discussed: (1) the neutrophil oxidase; (2) myeloperoxidase (MPO)-dependent oxidative microbicidal reactions; and (3) MPO-independent oxidative reactions. Topics included in section (A) are current views on the activation mechanism, redox composition, structural and topographic organization of the oxidase, and its respiratory products. In section (B), emphasis is placed on recent research on cidal mechanisms of HOCl, including the oxidative biochemistry of active chlorine compounds, identification of sites of lesions in bacteria, and attendant metabolic consequences. In section (C), we review the (bio)chemistry of H2O2 and .OH microbicidal reactions, with particular attention being given to addressing the controversial issue of probe methods to identify .OH radical and critical assessment of the recent proposal that MPO-independent killing arises from site-specific metal-catalyzed Fenton-type chemistry. PMID:2548810

  17. FcγRIII in ITP: it ain't over 'til it's over.

    PubMed

    McCrae, Keith R

    2016-01-01

    In this issue of Blood, Yu et al describe a novel anti–Fcγ receptor III (FcγRIII)-albumin fusion protein that inhibits the development of thrombocytopenia in a murine model of immune thrombocytopenia (ITP).1 The unique aspect of this protein is that it blocks FcγRIII-mediated uptake of antibody-coated platelets without activating FcγRIII and the associated inflammatory response. PMID:26744437

  18. 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

  19. Human cytomegalovirus Fcγ binding proteins gp34 and gp68 antagonize Fcγ receptors I, II and III.

    PubMed

    Corrales-Aguilar, Eugenia; Trilling, Mirko; Hunold, Katja; Fiedler, Manuela; Le, Vu Thuy Khanh; Reinhard, Henrike; Ehrhardt, Katrin; Mercé-Maldonado, Eva; Aliyev, Enver; Zimmermann, Albert; Johnson, David C; Hengel, Hartmut

    2014-05-01

    Human cytomegalovirus (HCMV) establishes lifelong infection with recurrent episodes of virus production and shedding despite the presence of adaptive immunological memory responses including HCMV immune immunoglobulin G (IgG). Very little is known how HCMV evades from humoral and cellular IgG-dependent immune responses, the latter being executed by cells expressing surface receptors for the Fc domain of IgG (FcγRs). Remarkably, HCMV expresses the RL11-encoded gp34 and UL119-118-encoded gp68 type I transmembrane glycoproteins which bind Fcγ with nanomolar affinity. Using a newly developed FcγR activation assay, we tested if the HCMV-encoded Fcγ binding proteins (HCMV FcγRs) interfere with individual host FcγRs. In absence of gp34 or/and gp68, HCMV elicited a much stronger activation of FcγRIIIA/CD16, FcγRIIA/CD32A and FcγRI/CD64 by polyclonal HCMV-immune IgG as compared to wildtype HCMV. gp34 and gp68 co-expression culminates in the late phase of HCMV replication coinciding with the emergence of surface HCMV antigens triggering FcγRIII/CD16 responses by polyclonal HCMV-immune IgG. The gp34- and gp68-dependent inhibition of HCMV immune IgG was fully reproduced when testing the activation of primary human NK cells. Their broad antagonistic function towards FcγRIIIA, FcγRIIA and FcγRI activation was also recapitulated in a gain-of-function approach based on humanized monoclonal antibodies (trastuzumab, rituximab) and isotypes of different IgG subclasses. Surface immune-precipitation showed that both HCMV-encoded Fcγ binding proteins have the capacity to bind trastuzumab antibody-HER2 antigen complexes demonstrating simultaneous linkage of immune IgG with antigen and the HCMV inhibitors on the plasma membrane. Our studies reveal a novel strategy by which viral FcγRs can compete for immune complexes against various Fc receptors on immune cells, dampening their activation and antiviral immunity. PMID:24830376

  20. 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. PMID:26436649

  1. 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

  2. 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

  3. 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

  4. Myeloperoxidase-mediated activation of xenobiotics by human leukocytes.

    PubMed

    Hofstra, A H; Uetrecht, J P

    1993-10-01

    Peripheral blood leukocytes contain a variety of enzymes that are capable of metabolising xenobiotics. The enzyme myeloperoxidase (MPO) appears to be the most important for drug metabolism. MPO is a peroxidase/oxidase and generates the powerful oxidant hypochlorous acid. MPO- or MPO-generated oxidants are capable of oxidizing a wide variety of compounds and a broad range of functional groups, especially those that contain nitrogen and sulfur. Leukocytes have a role in immune response; therefore, reactive intermediates generated by leukocyte metabolism of xenobiotics may have a role in idiosyncratic drug reactions, particularly those that are immune-mediated such as drug-induced lupus or agranulocytosis. PMID:8236277

  5. Uptake of indium-111-labeled leukocytes by brain metastasis

    SciTech Connect

    Balachandran, S.; Husain, M.M.; Adametz, J.R.; Pallin, J.S.; Angtuaco, T.L.; Boyd, C.M.

    1987-04-01

    Uptake of indium-labeled leukocytes was seen in two cases of histologically proven brain metastasis. In one, this led to misdiagnosis of the lesion as an abscess. On histological evaluation, a large number of white blood cells or macrophages was seen at the neoplastic sites. Reasons for leukocyte accumulation around metastatic brain neoplasms are discussed. In contrast to the current reports that indium-labeled leukocyte scans can differentiate intracranial infection from tumor, these cases demonstrate their lack of specificity in the detection of brain abscess.

  6. Comparison of the Fc fragment from a human IgG1 and its CH2, pFc', and tFc' subfragments. A study using reductive methylation and sup 13 C NMR

    SciTech Connect

    Jentoft, J.E.; Rayford, R. )

    1989-04-18

    The Fc fragment of a human monoclonal IgG1 was compared with subfragments containing (a) the intact CH2 domain (CH2 fragment) or (b) the intact CH3 domain (pFc' and tFc' fragments). All fragments were reductively {sup 13}C-methylated and their resulting dimethyllysyl resonances characterized in 0.1 M KCl as a function of pH by {sup 13}C NMR spectroscopy. Seven resonances were characterized for the 18 lysine residues of the Fc fragment, eight for the 12 lysines of the CH2 fragment, and five each for the 9 lysines of the pFc' and the 6 lysines of the tFc' fragments, respectively. The multiplicity of resonances indicates that the lysine residues in each fragment exist in a variety of microenvironments and that the fragments are all highly structured. The correspondence between 6 of the 12 or 13 perturbed lysine residues in the Fc fragment and the smaller subfragments indicates that the conformation of the CH2 and CH3 domains is largely unchanged in the smaller fragments. However, in addition to three lysines at the CH2-CH3 domain interface, whose environments were known to be disrupted in the smaller fragments, three or four lysine residues have somewhat different properties in the Fc fragment and in the subfragments, indicating that some local perturbations are included in the domain structure in the subfragments.

  7. Determination of Fc function with frozen red blood cells.

    PubMed

    Gurevich, V; Bertolini, J; Lyons, K

    2006-09-01

    The Fc function of immunoglobulins is commonly determined by an assay based on monitoring immunoglobulin induced, complement mediated red cell lysis. This assay requires a continuous source of fresh red cells. We have shown that the assay can be successfully performed with frozen red cells. The possibility of access to a stored standard stock of red cells will improve the convenience of performing the assay and could contribute to improved assay reproducibility. PMID:16500112

  8. Divergent roles for Fc receptors and complement in vivo.

    PubMed

    Ravetch, J V; Clynes, R A

    1998-01-01

    Recent results obtained in mice deficient in either FcRs or complement have revealed distinct functions for these two classes of molecules. While each is capable of interacting with antibodies or immune complexes, the two systems mediate distinct biological effector responses. Complement-deficient mice are unable to mediate innate immune responses to several bacterial pathogens and bacterial toxins, yet respond normally to the presence of cytotoxic antibodies and pathogenic immune complexes. In contrast, FcR-deficient mice display no defects in innate immunity or susceptibility to a variety of pathogens, yet they are unable to mediate inflammatory responses to cytotoxic IgG antibodies or IgG immune complexes, despite the presence of a normal complement system. These results lead to the surprising conclusion that these two systems have evolved distinct functions in host immunity, with complement and its receptors mediating the interaction of natural antibodies (IgM) with pathogens to effect protection, while FcRs couple the interaction of IgG antibodies to effector cells to trigger inflammatory sequelae. These results necessitate a fundamental revision of the role of these antibody-binding systems in the immune response. PMID:9597136

  9. 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

  10. Reproduction of the FC/DFC units in nucleoli.

    PubMed

    Smirnov, Evgeny; Hornáček, Matúš; Kováčik, Lubomír; Mazel, Tomáš; Schröfel, Adam; Svidenská, Silvie; Skalníková, Magdalena; Bartová, Eva; Cmarko, Dušan; Raška, Ivan

    2016-04-25

    The essential structural components of the nucleoli, Fibrillar Centers (FC) and Dense Fibrillar Components (DFC), together compose FC/DFC units, loci of rDNA transcription and early RNA processing. In the present study we followed cell cycle related changes of these units in 2 human sarcoma derived cell lines with stable expression of RFP-PCNA (the sliding clamp protein) and GFP-RPA43 (a subunit of RNA polymerase I, pol I) or GFP-fibrillarin. Correlative light and electron microscopy analysis showed that the pol I and fibrillarin positive nucleolar beads correspond to individual FC/DFC units. In vivo observations showed that at early S phase, when transcriptionally active ribosomal genes were replicated, the number of the units in each cell increased by 60-80%. During that period the units transiently lost pol I, but not fibrillarin. Then, until the end of interphase, number of the units did not change, and their duplication was completed only after the cell division, by mid G1 phase. This peculiar mode of reproduction suggests that a considerable subset of ribosomal genes remain transcriptionally silent from mid S phase to mitosis, but become again active in the postmitotic daughter cells. PMID:26934002

  11. Immunization with avian metapneumovirus harboring chicken Fc induces higher immune responses.

    PubMed

    Paudel, Sarita; Easwaran, Maheswaran; Jang, Hyun; Jung, Ho-Kyoung; Kim, Joo-Hun; Shin, Hyun-Jin

    2016-07-15

    In this study, we evaluated the immune responses of avian metapneumovirus harboring chicken Fc molecule. Stable Vero cells expressing chicken Fc chimera on its surface (Vero-cFc) were established, and we confirmed that aMPV grown in Vero-cFc incorporated host derived chimera Fc into the aMPV virions. Immunization of chicken with aMPV-cFc induced higher level of antibodies and inflammatory cytokines; (Interferon (IFN)-γ and Interleukin (IL)-1β) compared to those of aMPV. The increased levels of antibodies and inflammatory cytokines in chicken immunized with aMPV-cFc were statistically significantly (p<0.05) to that of aMPV and control. The aMPV-cFc group also generated the highest neutralizing antibody response. After challenges, chickens immunized with aMPV-cFc showed much less pathological signs in nasal turbinates and trachea so that we could confirm aMPV-cFc induced higher protection than that of aMPV. The greater ability of aMPV harboring chicken Fc to that of aMPV presented it as a possible vaccine candidate. PMID:27130629

  12. Modulation of tumor growth by inhibitory Fcγ receptor expressed by human melanoma cells

    PubMed Central

    Cassard, Lydie; Cohen-Solal, Joël F.G.; Galinha, Annie; Sastre-Garau, Xavier; Mathiot, Claire; Galon, Jérôme; Dorval, Thierry; Bernheim, Alain; Fridman, Wolf H.; Sautès-Fridman, Catherine

    2002-01-01

    The efficacy of anti-tumor IgG reflects the balance between opposing signals mediated by activating and inhibitory Fcγ receptors (FcγRs) expressed by effector cells. Here, we show that human malignant melanoma cells express the inhibitory low-affinity Fcγ receptor FcγRIIB1 in 40% of tested metastases. When melanoma cells were grafted in nude mice, a profound inhibition of FcγRIIB1 tumor growth that required the intracytoplasmic region of the receptor was observed. IgG immune complexes (ICs) may be required for this inhibition, since sera from nude mice bearing tumors contained IgG that decreased the proliferation of FcγRIIB1-positive cells in vitro, and tumor development of FcγRIIB1-positive melanoma lines was not inhibited in antibody-defective severe combined immunodeficiency (SCID) mice. Passive immunization of SCID mice with anti–ganglioside GD2 antibody resulted in significant inhibition of growth of FcγRIIB1-positive tumors in an intracytoplasmic-dependent manner. Altogether, these data suggest that human melanoma cells express biologically active inhibitory FcγRIIB1, which regulates their development upon direct interaction with anti-tumor antibodies. Therefore, FcγR expression on human tumors may be one component of the efficacy of antibody-mediated therapies, and FcγR-positive tumors could be the most sensitive candidates for such treatments. PMID:12438452

  13. Human CD4+ T-Cells: A Role for Low-Affinity Fc Receptors

    PubMed Central

    Chauhan, Anil K.

    2016-01-01

    Both lymphoid and myeloid cells express Fc receptors (FcRs). Low-affinity FcRs engage circulating immune complexes, which results in the cellular activation and pro-inflammatory cytokine production. FcRs participate in the internalization, transport, and/or recycling of antibodies and antigens. Cytosolic FcRs also route these proteins to proteasomes and antigen-presentation pathways. Non-activated CD4+ T-cells do not express FcRs. Once activated, naive CD4+ T-cells express FcγRIIIa, which, upon IC ligation, provide a costimulatory signal for the differentiation of these cells into effector cell population. FcγRIIIa present on CD4+ T-cell membrane could internalize nucleic acid-containing ICs and elicit a cross-talk with toll-like receptors. FcγRIIIa common γ-chain forms a heterodimer with the ζ-chain of T-cell receptor complex, suggesting a synergistic role for these receptors. This review first summarizes our current understanding of FcRs on CD4+ T-cells. Thereafter, I will attempt to correlate the findings from the recent literature on FcRs and propose a role for these receptors in modulating adaptive immune responses via TLR signaling, nucleic acid sensing, and epigenetic changes in CD4+ T-cells. PMID:27313579

  14. Potentiation of specific human in vitro immune responses by the Fc portion of human immunoglobulin.

    PubMed Central

    Morgan, E L; Weigle, W O

    1983-01-01

    Fc fragments derived from a human IgG1 myeloma protein were found to be a potent adjuvant for in vitro human immune responses. The addition of Fc to cultures of human PBL along with SRBC resulted in a pronounced enhancement of the primary in vitro anti-SRBC response. In addition to potentiating the humoral immune response, Fc was also found to augment the tetanus toxoid-induced T cell proliferative response. Augmentation of the immune response is mediated by Fc and not the result of an artifact due to the addition of extraneous protein to culture because neither intact IgG1 nor Fab fragments derived from this myeloma protein possessed any adjuvant properties. The temporal relationship of the administration of antigen and Fc to culture is critical for the potentiation of the immune response. The maximal Fc adjuvant effect was observed when Fc was added with antigen at the beginning of culture. PMID:6603935

  15. Identification of cyclic peptides able to mimic the functional epitope of IgG1-Fc for human FcγRI

    PubMed Central

    Bonetto, Stephane; Spadola, Loredana; Buchanan, Andrew G.; Jermutus, Lutz; Lund, John

    2009-01-01

    Identification of short, structured peptides able to mimic potently protein-protein interfaces remains a challenge in drug discovery. We report here the use of a naive cyclic peptide phage display library to identify peptide ligands able to recognize and mimic IgG1-Fc functions with FcγRI. Selection by competing off binders to FcγRI with IgG1 allowed the isolation of a family of peptides sharing the common consensus sequence TX2CXXθPXLLGCΦXE (θ represents a hydrophobic residue, Φ is usually an acidic residue, and X is any residue) and able to inhibit IgG1 binding to FcγRI. In soluble form, these peptides antagonize superoxide generation mediated by IgG1. In complexed form, they trigger phagocytosis and a superoxide burst. Unlike IgG, these peptides are strictly FcγRI-specific among the FcγRs. Molecular modeling studies suggest that these peptides can adopt 2 distinct and complementary conformers, each able to mimic the discontinuous interface contacts constituted by the Cγ2-A and -B chains of Fc for FcγRI. In addition, by covalent homodimerization, we engineered a synthetic bivalent 37-mer peptide that retains the ability to trigger effector functions. We demonstrate here that it is feasible to maintain IgG-Fc function within a small structured peptide. These peptides represent a new format for modulation of effector functions.—Bonetto, S., Spadola, L., Buchanan, A. G., Jermutus, L. Lund, J. Identification of cyclic peptides able to mimic the functional epitope of IgG1-Fc for human FcγRI. PMID:18957574

  16. 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

  17. The properties of (2Fo - Fc) and (Fo - Fc) electron-density maps at medium-to-high resolutions.

    PubMed

    Minichino, A; Habash, J; Raftery, J; Helliwell, J R

    2003-05-01

    This paper reports on the efficacy of (F(o) - F(c)) versus (2F(o) - F(c)) electron-density maps at 3.2 A resolution. Firstly, a study is reported of a simple truncation at 2.3 and 3.2 A of the 1.6 A resolution crystal structure of concanavalin A at room temperature [Emmerich et al. (1994), Acta Cryst. D50, 749-756] with 149 known bound water molecules. Secondly, the concanavalin A 1.6 A resolution model was re-refined but with the data truncated to 3.2 A. In a similar evaluation, these procedures were repeated for the apocrustacyanin A1 cryotemperature 1.4 A resolution model [Cianci et al. (2001), Acta Cryst. D57, 1219-1229]. Maps at 1.4, 2.3 and 3.2 A resolutions were first generated and the structure was then re-refined at 3.2 A and additionally at 2.3 A resolution. The results on concanavalin A show that the number of bound water molecules that are resolved decreases by two thirds from 1.6 to 3.2 A, but that key structural waters, for example at the transition metal and the calcium ion, are still resolved in the (F(o) - F(c)) map but not in the (2F(o) - F(c)) map. For apocrustacyanin A1, the results with these two difference maps were less clear-cut. Two key structural bound waters (w93 and w105) were selected that had been previously identified in beta-crustacyanin [Cianci et al. (2002), Proc. Natl Acad. Sci. USA, 99, 9795-9800] in protein-carotenoid interactions. The behaviour of w93 is similar to that of concanavalin A key waters, but that of w105 is not. These behaviours were therefore explored in finer resolution increments, namely 2.9, 2.7 and 2.5 A. Finally, further tests on "real" data sets for peanut lectin and concanavalin A at medium resolution confirm these map properties, namely that an (F(o) - F(c)) difference electron-density map is more effective than a (2F(o) - F(c)) map in showing bound water structure at lower resolutions ( approximately 3.2 A). This result is important since a growing number of protein crystal structure studies are concerned

  18. 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.

  19. 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.

  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. 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

  2. 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

  3. Production of monoclonal antibodies against canine leukocytes.

    PubMed

    Aguiar, Paulo Henrique Palis; Borges dos Santos, Roberto Robson; Lima, Carla Andrade; Rios de Sousa Gomes, Hilton; Larangeira, Daniela Farias; Santos, Patrícia Meira; Barrouin-Melo, Stella Maria; Conrado dos-Santos, Washington Luis; Pontes-de-Carvalho, Lain

    2004-04-01

    A panel of anti-canine leukocyte monoclonal antibodies (MAbs) was produced by immunizing BALB/c mice with canine peripheral blood mononuclear cells (PBMC), either resting or stimulated with concanavalin A (ConA). Three out of 28 clones-IH1, AB6, and HG6-screened by ELISA and producing antibody with the highest specificity for canine cell immunostaining, were subjected to three subsequent subcloning steps by limiting dilution, and selected for further characterization. These MAbs belonged to IgG1 (HG6 and IH1) and IgG2a (AB6) isotypes. The distribution of cell populations expressing the antigen recognized by the antibodies was identified by indirect immunoflorescence on canine PBMC and on tissue sections of lymph node, spleen, liver and skin. The possible crossreactivity with human PBMC was also examined in immunocytochemistry. One of the antibodies specifically recognized macrophages. The MAbs presented here can be foreseen as possible valuable diagnostic and research tools to study immune functions in dogs. PMID:15165486

  4. Influence of a single gamma-irradiation on rat microflora.

    PubMed

    Benová, K; Falis, M; Toropila, M; Sehnalková, H; Pastvová, L

    2002-01-01

    Changes in leukocyte counts and in the gut microflora of laboratory rats irradiated with single whole-body dose of gamma rays (5.0 Gy) were determined. The number of leukocytes was lower especially 1 and 2 weeks after irradiation. A significant decrease in lymphocytes was observed 1 week and in monocytes 1 and 2 weeks after irradiation. In parallel with these changes, an increase in common microflora was observed; some microorganisms, which normally are not present in duodenum, liver and mouth cavity, were detected in these organs. PMID:12422530

  5. 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. PMID:26067211

  6. 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. PMID:26121420

  7. CD99 is essential for leukocyte diapedesis in vivo.

    PubMed

    Dufour, Eric M; Deroche, Alana; Bae, Youngmee; Muller, William A

    2008-11-01

    Recruitment of leukocytes into inflamed tissue requires migration of leukocytes from the blood stream across the endothelial lining and the basement membrane of the local blood vessels. CD99 in humans is a 32-kDa highly O-glycosylated cell surface protein expressed on most leukocytes. The authors recently found CD99 to be expressed in leukocytes and at human endothelial cell contacts. Human CD99 is involved in homophilic interaction between the two cell types and participates in the transendothelial migration of monocytes and polymorphonuclear neutrophils (PMNs) in vitro. To test the role of CD99 in vivo, the authors cloned murine CD99 (muCD99), expressed it in vitro, and generated a blocking monoclonal antibody against it. We first showed that muCD99 is expressed on mouse leukocytes as well as enriched at the endothelial cell borders. Transfection of cells with muCD99 imparts on them the ability to aggregate in a CD99-dependent homophilic manner. Cells expressing muCD99 did not bind to cells expressing murine or human platelet endothelial call adhesion molecule (PECAM) or human CD99. In the thioglycollate peritonitis model of inflammation, anti-CD99 monoclonal antibody blocked the recruitment of neutrophils and monocytes by over 40% and 80%, respectively, at 18 h. Microscopy showed that this blocking occurred at the luminal surface of venules. The authors conclude that CD99 plays a major role in the emigration of leukocytes in vivo. PMID:18923973

  8. 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

  9. Airway distension promotes leukocyte recruitment in rat tracheal circulation.

    PubMed

    Lim, Lina H K; Wagner, Elizabeth M

    2003-11-01

    Mechanical distortion of blood vessels is known to activate endothelial cells. Whether airway distension likewise activates the vascular endothelium within the airway wall is unknown. Using intravital microscopy in the rat trachea, we investigated if airway distention with the application of positive end-expiratory pressure (PEEP) caused leukocyte recruitment to the airway. Tracheal postcapillary venules were visualized and leukocyte kinetics monitored in anesthetized, mechanically ventilated rats (80 breaths/minute, 6 ml/kg VT, 1 cm H(2)O PEEP). Leukocyte rolling velocity (Vwbc) and the number of adherent cells were not altered with normal ventilation over the course of 2 hours. Ventilation with sustained PEEP (8 cm H(2)O for 1 hour reduced Vwbc and increased adhesion, reaching a maximum at 1 hour of PEEP. Intermittent (2x and 5x) 8 cm H(2)O PEEP also induced a similar reduction in Vwbc, accompanied by an increase in adhesion. However, leukocyte recruitment after airway distension is localized to the airways because increased PEEP did not induce leukocyte recruitment in the mesenteric microcirculation or when PEEP was applied to the lung distal to the site of measurement. Pretreatment with endothelin receptor and selectin inhibitors blocked the effects of distension on leukocyte recruitment, suggesting their involvement in the proinflammatory response. PMID:12869357

  10. 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.

  11. Distribution and dosimetry of In-111 labeled leukocytes and platelets in humans

    SciTech Connect

    Goodwin, D.A.; Finston, R.A.; Smith, S.I.

    1981-06-01

    The distribution of In-111 labeled leukocytes and platelets was studied by whole body gamma camera imaging in patients. Images were made approximately one hour and 24 hours after IV injection, and stored in digital form in computer memory. Estimates of the quantitative organ distribution were made from the geometric mean of the anterior and posterior region of interest counts after suitable background subtraction. Nearly quantitative retention of cell activity was observed with little or no excretion seen in either gut or kidneys. Mixed leukocytes distributed in spleen, liver and bone marrow in decreasing order of concentration, similar at both times, with a transient lung uptake noted at the one hour time only. The dose from 0.5 mCi In-111-WBC's was: liver, 1.4 rad; spleen, 8.5 rad; marrow, 2.3 rad. Lymphocytes had similar distribution with the addition of inguinal and cervical lymph nodes. The dose from 0.5 mCi In-111-lymphocytes was: liver, 0.8 rad; spleen, 6.7 rad; marrow and lymphatic tissue, 1.4 rad. Platelets distributed primarily in the blood pool with most of the remainder concentrating in the spleen, with a small amount in the penis. The dose from 0.5 mCi of In-111-platelets was: liver, 3.2 rad; spleen, 8.6 rad; and whole body, 0.3 rad.

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

    PubMed Central

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

    2005-01-01

    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-1β 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-1β 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. PMID:16179391

  13. 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

  14. A Nonfucosylated Variant of the anti-HIV-1 Monoclonal Antibody b12 Has Enhanced FcγRIIIa-Mediated Antiviral Activity In Vitro but Does Not Improve Protection against Mucosal SHIV Challenge in Macaques

    PubMed Central

    Moldt, Brian; Shibata-Koyama, Mami; Rakasz, Eva G.; Schultz, Niccole; Kanda, Yutaka; Dunlop, D. Cameron; Finstad, Samantha L.; Jin, Chenggang; Landucci, Gary; Alpert, Michael D.; Dugast, Anne-Sophie; Parren, Paul W. H. I.; Nimmerjahn, Falk; Evans, David T.; Alter, Galit; Forthal, Donald N.; Schmitz, Jörn E.; Iida, Shigeru; Poignard, Pascal; Watkins, David I.

    2012-01-01

    Eliciting neutralizing antibodies is thought to be a key activity of a vaccine against human immunodeficiency virus (HIV). However, a number of studies have suggested that in addition to neutralization, interaction of IgG with Fc gamma receptors (FcγR) may play an important role in antibody-mediated protection. We have previously obtained evidence that the protective activity of the broadly neutralizing human IgG1 anti-HIV monoclonal antibody (MAb) b12 in macaques is diminished in the absence of FcγR binding capacity. To investigate antibody-dependent cellular cytotoxicity (ADCC) as a contributor to FcγR-associated protection, we developed a nonfucosylated variant of b12 (NFb12). We showed that, compared to fully fucosylated (referred to as wild-type in the text) b12, NFb12 had higher affinity for human and rhesus macaque FcγRIIIa and was more efficient in inhibiting viral replication and more effective in killing HIV-infected cells in an ADCC assay. Despite these more potent in vitro antiviral activities, NFb12 did not enhance protection in vivo against repeated low-dose vaginal challenge in the simian-human immunodeficiency virus (SHIV)/macaque model compared to wild-type b12. No difference in protection, viral load, or infection susceptibility was observed between animals given NFb12 and those given fully fucosylated b12, indicating that FcγR-mediated activities distinct from FcγRIIIa-mediated ADCC may be important in the observed protection against SHIV challenge. PMID:22457527

  15. 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. PMID:26255698

  16. Measuring functional connectivity using MEG: Methodology and comparison with fcMRI

    PubMed Central

    Brookes, Matthew J.; Hale, Joanne R.; Zumer, Johanna M.; Stevenson, Claire M.; Francis, Susan T.; Barnes, Gareth R.; Owen, Julia P.; Morris, Peter G.; Nagarajan, Srikantan S.

    2011-01-01

    Functional connectivity (FC) between brain regions is thought to be central to the way in which the brain processes information. Abnormal connectivity is thought to be implicated in a number of diseases. The ability to study FC is therefore a key goal for neuroimaging. Functional connectivity (fc) MRI has become a popular tool to make connectivity measurements but the technique is limited by its indirect nature. A multimodal approach is therefore an attractive means to investigate the electrodynamic mechanisms underlying hemodynamic connectivity. In this paper, we investigate resting state FC using fcMRI and magnetoencephalography (MEG). In fcMRI, we exploit the advantages afforded by ultra high magnetic field. In MEG we apply envelope correlation and coherence techniques to source space projected MEG signals. We show that beamforming provides an excellent means to measure FC in source space using MEG data. However, care must be taken when interpreting these measurements since cross talk between voxels in source space can potentially lead to spurious connectivity and this must be taken into account in all studies of this type. We show good spatial agreement between FC measured independently using MEG and fcMRI; FC between sensorimotor cortices was observed using both modalities, with the best spatial agreement when MEG data are filtered into the β band. This finding helps to reduce the potential confounds associated with each modality alone: while it helps reduce the uncertainties in spatial patterns generated by MEG (brought about by the ill posed inverse problem), addition of electrodynamic metric confirms the neural basis of fcMRI measurements. Finally, we show that multiple MEG based FC metrics allow the potential to move beyond what is possible using fcMRI, and investigate the nature of electrodynamic connectivity. Our results extend those from previous studies and add weight to the argument that neural oscillations are intimately related to functional

  17. Insulin radioreceptor assay on murine splenic leukocytes and peripheral erythrocytes

    SciTech Connect

    Shimizu, F.; Kahn, R.

    1982-02-01

    Insulin radioreceptor assays were developed using splenic leukocytes and peripheral erythrocytes from individual mice. Splenic leukocytes were prepared using an NH/sub 4/Cl buffer which did not alter insulin binding, but gave much higher yields than density gradient methods. Mouse erythrocytes were isolated from heparinized blood by three passages over a Boyum gradient, and a similar buffer was used to separate cells from free (/sup 125/I)iodoinsulin at the end of the binding incubation. Insulin binding to both splenic leukocytes and peripheral erythrocytes had typical pH, temperature, and time dependencies, and increased linearly with an increased number of cells. Optimal conditions for the splenic leukocytes (6 x 10/sup 7//ml) consisted of incubation with (/sup 125/I)iodoinsulin at 15 C for 2 h in Hepes buffer, pH 8.0. In cells from 20 individual mice, the specific (/sup 125/I)iodoinsulin binding was 2.6 +/- 0.1% (SEM), and nonspecific binding was 0.3 +/- 0.04% (10.6% of total binding). Erythrocytes (2.8 x 10/sup 9//ml) were incubated with (/sup 125/)iodoinsulin at 15 C for 2 h in Hepes buffer, pH 8.2. In cells from 25 individual mice, the specific (/sup 125/I)iodoinsulin binding was 4.5 +/- 0.2%, and nonspecific binding was 0.7 +/- 0.03% (13.6% of total binding). In both splenic leukocytes and peripheral erythrocytes, analysis of equilibrium binding data produced curvilinear Scatchard plots with approximately 3500 binding sites/leukocyte and 20 binding sites/erythrocyte. These data demonstrate that adequate numbers of splenic leukocytes and peripheral erythrocytes can be obtained from individual mice to study insulin binding in a precise and reproducible manner.

  18. Monoclonal antibodies and Fc fragments for treating solid tumors.

    PubMed

    Eisenbeis, Andrea M; Grau, Stefan J

    2012-01-01

    Advances in biotechnology, better understanding of pathophysiological processes, as well as the identification of an increasing number of molecular markers have facilitated the use of monoclonal antibodies and Fc fragments in various fields in medicine. In this context, a rapidly growing number of these substances have also emerged in the field of oncology. This review will summarize the currently approved monoclonal antibodies used for the treatment of solid tumors with a focus on their clinical application, biological background, and currently ongoing trials. PMID:22291463

  19. Monoclonal antibodies and Fc fragments for treating solid tumors

    PubMed Central

    Eisenbeis, Andrea M; Grau, Stefan J

    2012-01-01

    Advances in biotechnology, better understanding of pathophysiological processes, as well as the identification of an increasing number of molecular markers have facilitated the use of monoclonal antibodies and Fc fragments in various fields in medicine. In this context, a rapidly growing number of these substances have also emerged in the field of oncology. This review will summarize the currently approved monoclonal antibodies used for the treatment of solid tumors with a focus on their clinical application, biological background, and currently ongoing trials. PMID:22291463

  20. 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

  1. 40 CFR Table 25 to Subpart G of... - Effective Column Diameter (Fc)

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 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...

  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. 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

  4. Extravasation of leukocytes in comparison to tumor cells

    PubMed Central

    Strell, Carina; Entschladen, Frank

    2008-01-01

    The multi-step process of the emigration of cells from the blood stream through the vascular endothelium into the tissue has been termed extravasation. The extravasation of leukocytes is fairly well characterized down to the molecular level, and has been reviewed in several aspects. Comparatively little is known about the extravasation of tumor cells, which is part of the hematogenic metastasis formation. Although the steps of the process are basically the same in leukocytes and tumor cells, i.e. rolling, adhesion, transmigration (diapedesis), the molecules that are involved are different. A further important difference is that leukocyte interaction with the endothelium changes the endothelial integrity only temporarily, whereas tumor cell interaction leads to an irreversible damage of the endothelial architecture. Moreover, tumor cells utilize leukocytes for their extravasation as linkers to the endothelium. Thus, metastasis formation is indirectly susceptible to localization signals that are literally specific for the immune system. We herein compare the extravasation of leukocytes and tumor cells with regard to the involved receptors and the localization signals that direct the cells to certain organs and sites of the body. PMID:19055814

  5. Platelets Guide Leukocytes to Their Sites of Extravasation

    PubMed Central

    Puhr-Westerheide, Daniel; Pörnbacher, Michaela; Lauber, Kirsten; Krombach, Fritz; Reichel, Christoph Andreas

    2016-01-01

    Effective immune responses require the directed migration of leukocytes from the vasculature to the site of injury or infection. How immune cells “find” their site of extravasation remains largely obscure. Here, we identified a previously unrecognized role of platelets as pathfinders guiding leukocytes to their exit points in the microvasculature: upon onset of inflammation, circulating platelets were found to immediately adhere at distinct sites in venular microvessels enabling these cellular blood components to capture neutrophils and, in turn, inflammatory monocytes via CD40-CD40L-dependent interactions. In this cellular crosstalk, ligation of PSGL-1 by P-selectin leads to ERK1/2 MAPK-dependent conformational changes of leukocyte integrins, which promote the successive extravasation of neutrophils and monocytes to the perivascular tissue. Conversely, blockade of this cellular partnership resulted in misguided, inefficient leukocyte responses. Our experimental data uncover a platelet-directed, spatiotemporally organized, multicellular crosstalk that is essential for effective trafficking of leukocytes to the site of inflammation. PMID:27152726

  6. 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. PMID:26794844

  7. Limited role of charge matching in the interaction of human immunoglobulin A with the immunoglobulin A Fc receptor (Fc alpha RI) CD89.

    PubMed

    Pleass, Richard J; Dehal, Prabhjyot K; Lewis, Melanie J; Woof, Jenny M

    2003-07-01

    Human immunoglobulin A (IgA) mediates protective effector mechanisms through interaction with specific cellular Fc receptors (Fc alpha RI). Two IgA Fc interdomain loops (Leu257-Leu258 in the CH2 domain and Pro440-Phe443 in the CH3 domain) have previously been identified as critical for binding to Fc alpha RI. On the receptor, the interaction site for IgA has been localized to the EC1 domain. The essential Fc alpha RI residues involved are Tyr35, Tyr81 and Arg82, with contributions also from Arg52 and to a lesser extent from His85 and Tyr86. The basic nature of the side chains of some of the receptor residues implicated in ligand binding suggested that charge matching might play some role in the interaction. To address this possibility, we have generated five IgA1 mutants with point substitutions in acidic residues lying close to the putative interaction site and assessed their abilities to bind Fc alpha RI on human neutrophils. Mutants E254A, E254L and E437A displayed affinities for Fc alpha RI comparable to that of wild-type IgA1, while mutants D255A and D255V had only slightly reduced affinities for the receptor. Therefore, electrostatic interactions appear unlikely to play a significant role in the IgA-Fc alpha RI interaction. Moreover, the lack of effect of mutations in residues adjacent to those previously implicated in binding, reaffirms the importance of the interdomain loops in Fc alpha RI binding. PMID:12807477

  8. 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

  9. Targeting FcγRs to treat antibody-dependent autoimmunity.

    PubMed

    Yu, Xiaojie; Lazarus, Alan H

    2016-06-01

    Self-reactive antibodies represent a significant force in autoimmune disease induction. In antibody-dependent autoimmune syndromes such as immune thrombocytopenia (ITP), systemic lupus erythematosus (SLE), myasthenia gravis and rheumatoid arthritis (RA), autoantibodies exert their inflammatory effect through FcγRs, a well-established class of cell surface receptors that interact with the Fc domain of IgG. Down-regulating FcγR functionality presents an attractive strategy to treat antibody-dependent autoimmune diseases. Various approaches, including nonspecific blocking of the IgG binding site as well as specific targeting using antagonistic monoclonal antibodies, have been explored to modulate the interaction between the Fc portion of IgG and FcγRs. The exquisite specificity and favorable pharmacokinetics of IgG make monoclonal antibodies a preferred choice. Indeed, the first antagonistic monoclonal antibody against the human FcγRIIIA had shown efficacy in refractory ITP patients; however, the practicality of using anti-FcγRIII antibody as a therapeutic was hindered by its associated adverse events, a phenomenon recapitulated in animal models. In this review, we discuss the role of FcγRs in autoimmune diseases, and focus on a novel monovalent approach to target FcγRs to resolve antibody-mediated autoimmunity. PMID:26854400

  10. 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

  11. Meditation-State Functional Connectivity (msFC): Strengthening of the Dorsal Attention Network and Beyond

    PubMed Central

    Froeliger, Brett; Garland, Eric L.; Kozink, Rachel V.; Modlin, Leslie A.; Chen, Nan-Kuei; McClernon, F. Joseph; Greeson, Jeffrey M.; Sobin, Paul

    2012-01-01

    Meditation practice alters intrinsic resting-state functional connectivity (rsFC) in the default mode network (DMN). However, little is known regarding the effects of meditation on other resting-state networks. The aim of current study was to investigate the effects of meditation experience and meditation-state functional connectivity (msFC) on multiple resting-state networks (RSNs). Meditation practitioners (MPs) performed two 5-minute scans, one during rest, one while meditating. A meditation naïve control group (CG) underwent one resting-state scan. Exploratory regression analyses of the relations between years of meditation practice and rsFC and msFC were conducted. During resting-state, MP as compared to CG exhibited greater rsFC within the Dorsal Attention Network (DAN). Among MP, meditation, as compared to rest, strengthened FC between the DAN and DMN and Salience network whereas it decreased FC between the DAN, dorsal medial PFC, and insula. Regression analyses revealed positive correlations between the number of years of meditation experience and msFC between DAN, thalamus, and anterior parietal sulcus, whereas negative correlations between DAN, lateral and superior parietal, and insula. These findings suggest that the practice of meditation strengthens FC within the DAN as well as strengthens the coupling between distributed networks that are involved in attention, self-referential processes, and affective response. PMID:22536289

  12. Involvement of Fc Receptors in Disorders of the Central Nervous System

    PubMed Central

    Okun, Eitan; Mattson, Mark P.; Arumugam, Thiruma V.

    2009-01-01

    Immunoglobulins (Igs) are proteins with a highly variable antigen-binding domain and a constant region (Fc domain) that binds to a cell surface receptor (FcR). Activation of FcRs in immune cells (lymphocytes, macrophages and mast cells) triggers effector responses including cytokine production, phagocytosis and degranulation). In addition to their roles in normal responses to infection or tissue injury, and in immune-related diseases, FcRs are increasingly recognized for their involvement in neurological disorders. One or more FcRs are expressed in microglia, astrocytes, oligodendrocytes and neurons. Aberrant activation of FcRs in such neural cells may contribute to the pathogenesis of major neurodegenerative conditions including Alzheimer's disease, Parkinson's disease, ischemic stroke and multiple sclerosis. On the other hand, FcRs may play beneficial roles in counteracting pathological processes; for example, FcRs may facilitate removal of amyloid peptides from the brain and so protect against Alzheimer's disease. Knowledge of the functions of FcRs in the nervous system in health and disease is leading to novel preventative and therapeutic strategies for stroke, Alzheimer's disease and other neurological disorders. PMID:19844812

  13. Mouse model recapitulating human Fcγ receptor structural and functional diversity

    PubMed Central

    Smith, Patrick; DiLillo, David J.; Bournazos, Stylianos; Li, Fubin; Ravetch, Jeffrey V.

    2012-01-01

    The in vivo biological activities of IgG antibodies result from their bifunctional nature, in which antigen recognition by the Fab is coupled to the effector and immunomodulatory diversity found in the Fc domain. This diversity, resulting from both amino acid and glycan heterogeneity, is translated into cellular responses through Fcγ receptors (FcγRs), a structurally and functionally diverse family of cell surface receptors found throughout the immune system. Although many of the overall features of this system are maintained throughout mammalian evolution, species diversity has precluded direct analysis of human antibodies in animal species, and, thus, detailed investigations into the unique features of the human IgG antibodies and their FcγRs have been limited. We now report the development of a mouse model in which all murine FcγRs have been deleted and human FcγRs, encoded as transgenes, have been inserted into the mouse genome resulting in recapitulation of the unique profile of human FcγR expression. These human FcγRs are shown to function to mediate the immunomodulatory, inflammatory, and cytotoxic activities of human IgG antibodies and Fc engineered variants and provide a platform for the detailed mechanistic analysis of therapeutic and pathogenic IgG antibodies. PMID:22474370

  14. [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

  15. Manipulating leukocyte interactions in vivo through optogenetic chemokine release.

    PubMed

    Sarris, Milka; Olekhnovitch, Romain; Bousso, Philippe

    2016-06-01

    Light-mediated release of signaling ligands, such as chemoattractants, growth factors, and cytokines is an attractive strategy for investigation and therapeutic targeting of leukocyte communication and immune responses. We introduce a versatile optogenetic method to control ligand secretion, combining UV-conditioned endoplasmic reticulum-to-Golgi trafficking and a furin-processing step. As proof of principle, we achieved light-triggered chemokine secretion and demonstrated that a brief pulse of chemokine release can mediate a rapid flux of leukocyte contacts with target cells in vitro and in vivo. This approach opens new possibilities for dynamic investigation of leukocyte communication in vivo and may confer the potential to control the local release of soluble mediators in the context of immune cell therapies. PMID:27057000

  16. 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.

  17. Restricted motion of the conserved immunoglobulin G1 N-glycan is essential for efficient FcγRIIIa binding

    PubMed Central

    Subedi, Ganesh P.; Hanson, Quinlin M.; Barb, Adam W.

    2014-01-01

    Summary Immunoglobulin G1(IgG1)-based therapies are widespread and many function through interactions with low-affinity Fc γ receptors (FcγR). N-glycosylation of the IgG1 Fc domain is required for FcγR binding, though it is unclear why. Structures of the FcγR:Fc complex fail to explain this because the FcγR polypeptide does not bind the N-glycan. Here we identify a link between motion of the N-glycan and Fc:FcγRIIIa affinity that explains the N-glycan requirement. Fc F241 and F243 mutations decreased the N-glycan/polypeptide interaction and increased N-glycan mobility. The affinity of the Fc mutants for FcγRIIIa was directly proportional to the degree of glycan restriction (R2=0.82). The IgG1 Fc K246F mutation stabilized the N-glycan and enhanced affinity for FcγRIIIa. Allosteric modulation of a protein/protein interaction represents a previously undescribed role for N-glycans in biology. Conserved features suggesting a similar N-glycan/aromatic interaction were also found in IgD, E and M, but not A. PMID:25199692

  18. Upregulation of Leukocytic Syncytin-1 in Acute Myeloid Leukemia Patients.

    PubMed

    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 AND 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

  19. 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

  20. Constitutive and cytokine-induced expression of human leukocyte antigens and cell adhesion molecules by human myotubes.

    PubMed Central

    Michaelis, D.; Goebels, N.; Hohlfeld, R.

    1993-01-01

    Understanding the immunobiology of muscle is relevant to muscular autoimmune diseases and to gene therapies based on myoblast transfer. We have investigated the constitutive and cytokine-induced intra- and extracellular expression of histocompatibility human leukocyte antigens (HLA) and cell adhesion molecules by multinucleated human myotubes using immunofluorescence microscopy. Myotubes constitutively expressed HLA class I but not HLA class II. Exposure to interferon-gamma, but not tumor necrosis factor-alpha, induced HLA-DR in the cytoplasm and on the surface membrane of approximately 40 to 95% of cultured myotubes. Surface expression was strongest in perinuclear membrane areas, and cytoplasmic expression was strongest at branching points and at the tips of myotubes. HLA-DP and HLA-DQ were not expressed in detectable amounts. Both interferon-gamma and tumor necrosis factor-alpha induced the intercellular adhesion molecule-1 (CD54) in the cytoplasm and on the surface of nearly all myotubes. The distribution of intercellular adhesion molecule-1 and HLA-DR was similar but not identical in double-positive myotubes. The leukocyte function-associated (LFA) adhesion molecules LFA-1 (CD11a/CD18), LFA-2 (CD2), and LFA-3 (CD58) could not be detected in the cytoplasm or on the surface. Our results indicate that cytokine-induced myotubes can participate in immune interactions with T lymphocytes. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:8214008

  1. Leukocyte segmentation and classification in blood-smear images.

    PubMed

    Ramoser, Herbert; Laurain, Vincent; Bischof, Horst; Ecker, Rupert

    2005-01-01

    The detection and classification of leukocytes in blood smear images is a routine task in medical diagnosis. In this paper we present a fully automated approach to leukocyte segmentation that is robust with respect to cell appearance and image quality. A set of features is used to describe cytoplasm and nucleus properties. Pairwise SVM classification is used to discriminate between different cell types. Evaluation on a set of 1166 images (13 classes) resulted in 95% correct segmentations and 75% to 99% correct classification (with reject option). PMID:17280945

  2. 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.

  3. 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

  4. 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

  5. Monoclonal Antibodies Specific for Human IgM Fc Receptor Inhibit Ligand-binding Activity

    PubMed Central

    Kubagawa, Yoshiki; Honjo, Kazuhito; Kang, Dong-Won

    2014-01-01

    A panel of six different murine hybridoma clones secreting IgG monoclonal antibodies (MAbs) specific for the human IgM Fc receptor (FcμR) was generated. All MAbs specifically precipitated a major protein of ∼60 kDa from membrane lysates of FcμR-bearing, but not FcμR-negative, cells as did IgM-ligands. Pre-incubation of membrane lysate of FcμR-bearing cells with these MAbs completely removed the ∼60 kDa IgM-reactive protein. By using recombinant human/mouse chimeric FcμR proteins, the epitope recognized by HM7 and HM10 MAbs was mapped to the Ig-like domain of human FcμR, whereas the other MAbs recognized the stalk region. Pre-incubation of FcμR+ cells with the Ig-like domain-specific MAbs, but not with others, markedly inhibited subsequent IgM-ligand binding. A similar, but much weaker, inhibition was also observed when the incubation order was reversed. When FcμR+ cells were simultaneously incubated with both IgM-ligands and MAbs, HM7 MAb efficiently competed with IgM for FcμR binding. Unlike control Jurkat cells, FcμR-bearing cells were resistant to apoptosis induced by agonistic IgM anti-Fas MAb (CH11); however, addition of the HM7 MAb inhibited the interaction of the Fc portion of CH11 MAb with FcμR, thereby promoting apoptosis of FcμR-bearing Jurkat cells. The variable regions of the HM7 MAb were composed of Ighv14-3, Ighd1-2, and Ighj2 for the γ2b heavy chain and Igk3-4 and Igkj2 for the κ light chain. These findings suggest that HM7 MAb efficiently blocks the ligand-binding activity of FcμR. PMID:25545208

  6. 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

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

    PubMed

    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

  8. 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. PMID:24243971

  9. Fc-fragment removal allows the EPO-Fc fusion protein to be detected in blood samples by IEF-PAGE.

    PubMed

    Postnikov, Pavel; Krotov, Grigory; Mesonzhnik, Natalia; Efimova, Yulia; Rodchenkov, Grigory

    2015-01-01

    EPO-Fc proteins have been under investigation as a potential drug for treating anaemia and have shown larger half-life values than other erythropoiesis-stimulating agents (ESAs). Sodium dodecyl sulfate/sodium N-lauroylsarcosinate polyacrylamide gel electrophoresis (SDS/SAR-PAGE) methods and subsequent immunoblotting are used for routine anti-doping analysis. This paper reports that EPO-Fc fusion proteins can be detected in serum samples by isoelectric focusing-polyacrylamide gel electrophoresis (IEF-PAGE) in carrier ampholyte-based gels with a pH 2-6 gradient after removing the Fc part via site-specific IdeS protease cleavage. The IdeS-digested EPO-Fc protein yields three fragments: two Fc fragments and one dimeric EPO-hinge fragment. After IEF-PAGE was followed by double Western blotting with chemiluminescent detection, the dimeric EPO-hinge fragment showed a unique isoelectric pattern, which differed from those of any other currently known analogue of EPO. We observed that the removal of the Fc fragment from EPO-Fc reduced the apparent molecular weight of entire fusion protein and increased its electrophoretic mobility. As a result, the band for the EPO-hinge fragment was located in a region between the rEPO and NESP standards, at which lower amounts of serum proteins are present. Simple and selective protocols for determining the EPO-Fc protein in human serum were developed to extend the methodological anti-doping arsenal. This protocol has been characterized. The limit of detection (LOD) of the IEF-PAGE method was 20 pg, and that of SDS/SAR-PAGE was 15 pg. PMID:26695487

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

    PubMed Central

    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

  11. 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

  12. Targeted IgA Fc receptor I (FcαRI) therapy in the early intervention and treatment of pristane-induced lupus nephritis in mice.

    PubMed

    Liu, C; Kanamaru, Y; Watanabe, T; Tada, N; Horikoshi, S; Suzuki, Y; Liu, Z; Tomino, Y

    2015-09-01

    The Fc receptor I for IgA (FcαRI) down-regulates humoral immune responses and modulates the risk of autoimmunity. This study aimed to investigate whether FcαRI targeting can affect progression of pristine-induced lupus nephritis. In the first experiment (early intervention), four groups of animals were evaluated: untreated FcαRI/FcRγ transgenic (Tg) mice and Tg mice administered control antibody (Ctr Fab), saline and anti-FcαRI Fab [macrophage inflammatory protein (MIP)-8a], respectively, three times a week for 29 weeks, after being injected once intraperitoneally with 0·5 ml pristane. In the second experiment, antibody injection started after the onset of nephritis and was carried out for 2 months, with similar groups as described above. MIP-8a improved proteinuria, decreased the amounts of glomerular injury markers, serum interleukin (IL)-6, IL-1 and monocyte chemoattractant protein (MCP)-1, and F4/80 macrophages in the interstitium and glomeruli, in both experiments. When MIP-8a was used as early intervention, a decrease in mouse serum anti-nuclear antibody (ANA) titres and reduced deposition of immunoglobulins in glomeruli were observed. This effect was associated with reduced serum titres of immunoglobulin (Ig)G2a but not IgG1, IgG2b and IgG3. Furthermore, pathological analysis showed lower glomerular activity index and less fibronectin in MIP-8a treated mice. This study suggests that FcαRI targeting could halt disease progression and lupus activation by selective inhibition of cytokine production, leucocyte recruitment and renal inflammation. Our findings provide a basis for the use of FcαRI as a molecular target for the treatment of lupus. PMID:25907714

  13. Transfer of IgG in the female genital tract by MHC class I-related neonatal Fc receptor (FcRn) confers protective immunity to vaginal infection

    PubMed Central

    Palaniyandi, Senthilkumar; Zeng, Rongyu; Tuo, Wenbin; Roopenian, Derry C.; Zhu, Xiaoping

    2011-01-01

    IgG is a major Ig subclass in mucosal secretions of the human female genital tract, where it predominates over the IgA isotype. Despite the abundance of IgG, surprisingly little is known about where and how IgG enters the lumen of the genital tract and the exact role local IgG plays in preventing sexually transmitted diseases. We demonstrate here that the neonatal Fc receptor, FcRn, is expressed in female genital tract epithelial cells of humans and mice and binds IgG in a pH-dependent manner. In vitro we show that FcRn mediates bidirectional IgG transport across polarized human endometrial HEC-1-A monolayers and primary human genital epithelial cells. Furthermore, endosomal acidification appears to be a prerequisite for FcRn-mediated IgG transcytosis; IgG transcytosis was demonstrated in vivo by translocation of systemically administered IgG into the genital lumen in WT but not FcRn-KO mice. The biological relevance of FcRn-transported IgG was demonstrated by passive immunization using herpes simplex virus-2 (HSV-2)–specific polyclonal serum, which conferred significantly higher protection against intravaginal challenge infection by the HSV-2 186 strain in WT mice than in FcRn-KO mice. These studies demonstrate that FcRn-mediated transport is a mechanism by which IgG can act locally in the female genital tract in immune surveillance and in host defense against sexually transmitted diseases. PMID:21368166

  14. 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

  15. Altered Ig levels and antibody responses in mice deficient for the Fc receptor for IgM (FcμR).

    PubMed

    Honjo, Kazuhito; Kubagawa, Yoshiki; Jones, Dewitt M; Dizon, Brian; Zhu, Zilu; Ohno, Hiroshi; Izui, Shozo; Kearney, John F; Kubagawa, Hiromi

    2012-09-25

    Cell surface Fc receptor for IgM antibody (FcμR) is the most recently identified member among FcRs. We determined the cellular distribution of mouse FcμR and the functional consequences of Fcmr disruption. Surface FcμR expression was restricted to B-lineage cells, from immature B to plasma cells, except for a transient down-modulation during germinal center reactions. Fcmr ablation had no significant effect on overall B- and T-cell development, but led to a reduction of marginal zone B cells and an increase in splenic B1 B cells. Preimmune serum IgM in mutant mice was significantly elevated as were natural autoantibodies. When immunized with live attenuated pneumococci, mutant mice mounted robust antibody responses against phosphorylcholine, but not protein, determinants compared with wild-type mice. By contrast, upon immunization with a hapten-carrier conjugate, nitrophenyl-coupled chicken γ-globulin (NP-CGG), the mutant mice had a diminished primary IgG1 response to both NP and CGG. These findings suggest that FcμR has an important role in IgM homeostasis and regulation of humoral immune responses. PMID:22984178

  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. PMID:24511528

  17. 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. PMID:25918233

  18. INDUCTION OF ACTIVATION ANTIGENS ON HUMAN NATURAL KILLER CELLS MODIFIED THROUGH THE FC-Y RECEPTOR

    EPA Science Inventory

    NK cells, defined here as lymphocytes bearing the CD16 Ag found on the NK cell Fc-y receptor (FcR), are known to enter a proliferative and activated state in response to stimulation with IL-2 as assessed by clonal expansion, short-term DNA synthesis, and de novo expression of lym...

  19. Differential Fc-receptor engagement drives an anti-tumor vaccinal effect

    PubMed Central

    DiLillo, David J.; Ravetch, Jeffrey V.

    2015-01-01

    Summary Passively-administered anti-tumor mAbs rapidly kill tumor targets via FcγR-mediated cytotoxicity (ADCC), a short-term process. However, anti-tumor mAb treatment can also induce a vaccinal effect, in which mAb-mediated tumor death induces a long-term anti-tumor cellular immune response. To determine how such responses are generated, we utilized a murine model of an anti-tumor vaccinal effect against a model neoantigen. We demonstrate that FcγR expression by CD11c+ antigen-presenting cells is required to generate anti-tumor T cell responses upon ADCC-mediated tumor clearance. Using FcγR-humanized mice, we demonstrate that anti-tumor huIgG1 must engage hFcγRIIIA on macrophages to mediate ADCC, but also engage hFcγRIIA, the sole hFcγR expressed by human DCs, to generate a potent vaccinal effect. Thus, while next-generation anti-tumor antibodies with enhanced binding to only hFcγRIIIA are now in clinical use, ideal anti-tumor antibodies must be optimized for both cytotoxic effects as well as hFcγRIIA engagement on DCs to stimulate long-term anti-tumor cellular immunity. PMID:25976835

  20. 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

  1. 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.

  2. Human neutrophil Fcγ receptors initiate and play specialized nonredundant roles in antibody-mediated inflammatory diseases

    PubMed Central

    Tsuboi, Naotake; Asano, Kenichi; Lauterbach, Michael; Mayadas, Tanya N.

    2008-01-01

    Summary Antibody-antigen complex mediated inflammation is integral to the pathogenesis of many autoimmune diseases. Mice deficient in the γ-chain of Fc-receptors are protected in IgG-mediated glomerulonephritis and the Arthus reaction and FcR-bearing mast cells and macrophages have been assigned primary roles in these processes. Here we demonstrate that neutrophil selective transgenic expression of the two uniquely human activating FcγRs, FcγRIIA and FcγRIIIB was sufficient to restore susceptibility to progressive anti-glomerular basement membrane (GBM) nephritis and the cutaneous Reverse Passive Arthus (RPA) reaction in γ-chain deficient mice. Both FcγRIIA and FcγRIIIB mediated robust neutrophil accumulation in tissues suggesting direct roles for these human receptors in IC-induced neutrophil recruitment, while FcγRIIA alone mediated organ injury. In an acute model of anti-GBM nephritis, both FcγRIIIB and FcγRIIA promoted initial neutrophil recruitment to glomerular immune-complexes (ICs) accessible to circulating cells, while FcγRIIA further sustained accumulation. In a model of soluble ICs deposited strictly within the post-capillary venules of the cremaster muscle, FcγRIIIB was solely responsible for converting initial selectin-dependent tethers to slow rolling and adhesion. However, in the cremaster RPA reaction, dependent on vascular and tissue accumulation of soluble ICs, FcγRIIA predominated in neutrophil recruitment that was dependent on G-protein coupled receptor activation. Thus, human FcγRs on neutrophils serve as the primary molecular links between ICs and immunological disease with FcγRIIA promoting tissue injury, and FcγRIIIB and FcγRIIA displaying specialized context-dependent functions in IC-induced neutrophil recruitment. PMID:18538590

  3. Studies on gonococcus infection. XV. Identification of surface proteins of Neisseria gonorrhoeae correlated with leukocyte association.

    PubMed Central

    King, G J; Swanson, J

    1978-01-01

    Neisseria gonorrhoeae which exhibit high levels of leukocyte association have a surface protein which is considerably diminished in isogenic gonococci which exhibit low levels of leukocyte association (LA). The LA protein exhibits strain variation in molecular weight and immunogenicity. Membranes derived from LA+ and LA- organisms show quantitative differences in their adsorption to leukocytes; these differences are analogous to those found for the intact organisms regarding their association with leukocytes. Images PMID:211086

  4. 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

  5. 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

  6. Improved survival of newborns receiving leukocyte transfusions for sepsis

    SciTech Connect

    Cairo, M.S.; Rucker, R.; Bennetts, G.A.; Hicks, D.; Worcester, C.; Amlie, R.; Johnson, S.; Katz, J.

    1984-11-01

    To determine the role of polymorphonuclear (PMN) leukocyte transfusions in neonates with sepsis, 23 consecutive newborns were prospectively randomly selected during an 18-month period in a treatment plan to receive polymorphonuclear leukocyte transfusions with supportive care or supportive care alone. Thirteen neonates received transfusions every 12 hours for a total of five transfusions. Each transfusion consisting of 15 mL/kg of polymorphonuclear leukocytes was subjected to 1,500 rads of radiation. The polymorphonuclear leukocytes were obtained by continuous-flow centrifugation leukapheresis and contained 0.5 to 1.0 X 10(9) granulocytes per 15 mL with less than 10% lymphocytes. Positive findings on blood cultures were obtained in 14/23 patients and seven were randomly selected for each treatment group. Absolute granulocyte counts were less than 1,500/microL in 13 patients but tibial bone marrow examinations revealed that the neutrophil supply pool was depleted in only three patients. The survival was significantly greater in the treatment group compared with the group that did not receive transfusions.

  7. Recent advances in microscopic techniques for visualizing leukocytes in vivo.

    PubMed

    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

  8. Intracellular Penetration and Activity of Gemifloxacin in Human Polymorphonuclear Leukocytes

    PubMed Central

    García, Isabel; Pascual, Alvaro; Ballesta, Sofía; Joyanes, Providencia; Perea, Evelio J.

    2000-01-01

    The intracellular penetration and activity of gemifloxacin in human polymorphonuclear leukocytes (PMN) were evaluated. Gemifloxacin reached intracellular concentrations eight times higher than extracellular concentrations. The uptake was rapid, reversible, and nonsaturable and was affected by environmental temperature, cell viability, and membrane stimuli. At therapeutic extracellular concentrations, gemifloxacin showed intracellular activity against Staphylococcus aureus. PMID:11036051

  9. 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

  10. 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.

  11. The spreading of leukocytes released from their liquid environment.

    PubMed

    Cuadra, M

    1978-08-15

    It is known that while leukocytes in conventional blood smears reveal their structures, in smears of erythrocyte-free suspension (EFS) they show a tendency to pyknosis. From the present study it appears that: 1. When any leukocyte suspension is subjected to drying on slides the cells undergo shrinkage (pyknosis in stained state) because their water content is extracted by the suspending fluid that is rendered increasingly hypertonic during drying. 2. When the leukocytes, which while floating within physiological fluids are ball-shaped, are entirely released from their suspending fluid, they suddenly spread into flat cells because the capillary force between the cell membranes and glass overcomes the surface tension of the cells. 3. In contrast to shrunken or even normal (spherical) cells, spread cells are able to display their morphology. Using the smear technique, the cell density of the suspension will determine whether spreading or shrinkage are to occur; with normal blood (high density) the release and consequently the spread are achieved; with EFS (usually of low density) an inadequate release and consequently shrinkage occur. 4. A device (cell spreader) for spreading leukocytes of EFS is presented. PMID:678682

  12. 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

  13. 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.

  14. Secretory leukocyte proteinase inhibitor is a major leukocyte elastase inhibitor in human neutrophils.

    PubMed

    Sallenave, J M; Si Tahar, M; Cox, G; Chignard, M; Gauldie, J

    1997-06-01

    Secretory leukocyte proteinase inhibitor (SLPI) is the main neutrophil elastase (HLE) inhibitor found in the upper airways during pulmonary inflammation. It has been shown to be synthesized and secreted in vitro by epithelial cells and has been localized in tracheal glands and bronchiolar epithelial cells by immunocytochemistry. In this study, using immunodetection and immunopurification techniques with specific anti-SLPI immunoglobulin G (IgG), we show that SLPI is present as a native 14-kDa molecule in neutrophil cytosol. In addition, we demonstrate that SLPI is the major inhibitor of HLE present in neutrophil cytosol because pre-incubation with specific anti-SLPI IgG was able to inhibit completely the anti-HLE activity of the cytosol. SLPI can be secreted (probably in an inactive form) by neutrophils and its secretion is enhanced when the cells are stimulated with phorbol myristate acetate (PMA). Elafin, an elastase-specific inhibitor, is also present in minute amounts in neutrophil cytosol and its secretion can be up-regulated. The presence of SLPI in the cytosol of neutrophils may serve as a protective screen against proteinases spilling from azurophilic granules. An alternative or supplementary role may be the maintenance of a differentiated phenotype. PMID:9201260

  15. Functional Role of FcγRIIB in the Regulation of Mesenchymal Stem Cell Function

    PubMed Central

    Zhu, Tianyi; Chen, Ruohua; Li, Zeng; Tian, Jun; Deng, Changwen; Zhang, Xingxing; Zhang, Koudong; Tong, Linrong; Yu, Yizhi; Bai, Chong

    2016-01-01

    Mesenchymal stem cells (MSCs) derived from bone marrow are plural-potent stem cells with immune regulatory functions. We aimed to evaluate role of FcγRIIB in the regulation of bone marrow-derived MSC function. MSCs were prepared from mouse bone marrow derived from wild-type (WT) or FcγRIIB-deficient (FcγRIIB-/-) mice. MSCs were co-cultured with bone marrow-derived dendritic cells (BMDCs), and BMDC maturation and function were evaluated by flow cytometric analysis and carboxyfluorescein succinimidyl ester-labeled OT-II T-cell addition. An acute asthma model was established by aeresol ovalbumin challenge in mice. Mice received WT or FcγRIIB-/- MSC therapy. Lung function was evaluated by histological examination and cytokine production measurement. mRNA and protein expression levels of target genes were examined by real-time quantitative polymerase chain reactionor western blotting. We found that MSCs derived from bone marrow exhibit a high level of FcγRIIB expression. FcγRIIB deficiency impaired the suppressive function of MSCs, as FcγRIIB deficiency efficiently reversed the inhibitory effect of MSCs on BMDC maturation and function. Additionally, FcγRIIB-/-MSCs were less potent at suppressing asthma in model mice, possibly through reduced expression of Smad2, Smad3, Cox-2, and prostaglandin E2 in FcγRIIB-/-MSCs. FcγRIIB might play an essential role in regulating the inhibitory effects of MSCs derived from bone marrow. PMID:26941575

  16. Functional Role of FcγRIIB in the Regulation of Mesenchymal Stem Cell Function.

    PubMed

    Zhu, Tianyi; Chen, Ruohua; Li, Zeng; Tian, Jun; Deng, Changwen; Zhang, Xingxing; Zhang, Koudong; Tong, Linrong; Yu, Yizhi; Bai, Chong

    2016-01-01

    Mesenchymal stem cells (MSCs) derived from bone marrow are plural-potent stem cells with immune regulatory functions. We aimed to evaluate role of FcγRIIB in the regulation of bone marrow-derived MSC function. MSCs were prepared from mouse bone marrow derived from wild-type (WT) or FcγRIIB-deficient (FcγRIIB-/-) mice. MSCs were co-cultured with bone marrow-derived dendritic cells (BMDCs), and BMDC maturation and function were evaluated by flow cytometric analysis and carboxyfluorescein succinimidyl ester-labeled OT-II T-cell addition. An acute asthma model was established by aeresol ovalbumin challenge in mice. Mice received WT or FcγRIIB-/- MSC therapy. Lung function was evaluated by histological examination and cytokine production measurement. mRNA and protein expression levels of target genes were examined by real-time quantitative polymerase chain reactionor western blotting. We found that MSCs derived from bone marrow exhibit a high level of FcγRIIB expression. FcγRIIB deficiency impaired the suppressive function of MSCs, as FcγRIIB deficiency efficiently reversed the inhibitory effect of MSCs on BMDC maturation and function. Additionally, FcγRIIB-/-MSCs were less potent at suppressing asthma in model mice, possibly through reduced expression of Smad2, Smad3, Cox-2, and prostaglandin E2 in FcγRIIB-/-MSCs. FcγRIIB might play an essential role in regulating the inhibitory effects of MSCs derived from bone marrow. PMID:26941575

  17. Toll-like receptor 2 ligands regulate monocyte Fcγ receptor expression and function.

    PubMed

    Shah, Prexy; Fatehchand, Kavin; Patel, Hemal; Fang, Huiqing; Justiniano, Steven E; Mo, Xiaokui; Jarjoura, David; Tridandapani, Susheela; Butchar, Jonathan P

    2013-04-26

    Fcγ receptor (FcγR) clustering on monocytes/macrophages results in phagocytosis and inflammatory cytokine production, which serve to eliminate antibody-opsonized targets and activate neighboring immune cells. Toll-like receptor 2 (TLR2), which recognizes a range of both bacterial and fungal components, elicits strong proinflammatory responses in these cells when stimulated by ligands, either natural or synthetic. Thus, we explored the possibility that TLR2 agonists could strengthen FcγR activity within the context of antibody therapy. Human peripheral blood monocytes treated with the TLR2 agonist Pam2CSK4 showed significantly enhanced FcγR-mediated cytokine production as well as phagocytic ability. An examination of the molecular mechanism behind this enhancement revealed increased expression of both FcγRIIa and the common γ subunit following Pam2CSK4 treatment. Interestingly however, expression of the inhibitory receptor FcγRIIb was also modestly increased. Further investigation revealed that Pam2CSK4 also dramatically decreased the expression of SHIP, the major mediator of FcγRIIb inhibitory activity. Using a murine Her2/neu solid tumor model of antibody therapy, we found that Pam2CSK4 significantly enhanced the ability of anti-Her2 antibody to reduce the rate of tumor growth. To verify that the FcγR enhancement was not unique to the diacylated Pam2CSK4, we also tested Pam3CSK4, a related triacylated TLR2 agonist. Results showed significant enhancement in FcγR function and expression. Taken together, these findings indicate that TLR2 activation can positively modulate FcγR and suggest that TLR2 agonists should be considered for testing as adjuvants for antitumor antibody therapy. PMID:23504312

  18. 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. PMID:26254421

  19. Fecal Leukocytes in Children Infected with Diarrheagenic Escherichia coli▿

    PubMed Central

    Mercado, Erik H.; Ochoa, Theresa J.; Ecker, Lucie; Cabello, Martin; Durand, David; Barletta, Francesca; Molina, Margarita; Gil, Ana I.; Huicho, Luis; Lanata, Claudio F.; Cleary, Thomas G.

    2011-01-01

    The purpose of this study was to determine the presence and quantity of fecal leukocytes in children infected with diarrheagenic Escherichia coli and to compare these levels between diarrhea and control cases. We analyzed 1,474 stool samples from 935 diarrhea episodes and 539 from healthy controls of a cohort study of children younger than 2 years of age in Lima, Peru. Stools were analyzed for common enteric pathogens, and diarrheagenic E. coli isolates were studied by a multiplex real-time PCR. Stool smears were stained with methylene blue and read by a blinded observer to determine the number of polymorphonuclear leukocytes per high-power field (L/hpf). Fecal leukocytes at >10 L/hpf were present in 11.8% (110/935) of all diarrheal episodes versus 1.1% (6/539) in controls (P < 0.001). Among stool samples with diarrheagenic E. coli as the only pathogen isolated (excluding coinfection), fecal leukocytes at >10 L/hpf were present in 8.5% (18/212) of diarrhea versus 1.3% (2/157) of control samples (P < 0.01). Ninety-five percent of 99 diarrheagenic E. coli diarrhea samples were positive for fecal lactoferrin. Adjusting for the presence of blood in stools, age, sex, undernutrition, and breastfeeding, enterotoxigenic E. coli (ETEC) isolation as a single pathogen, excluding coinfections, was highly associated with the presence of fecal leukocytes (>10 L/hpf) with an odds ratio (OR) of 4.1 (95% confidence interval [CI], 1.08 to 15.51; P < 0.05). Although diarrheagenic E. coli was isolated with similar frequencies in diarrhea and control samples, clearly it was associated with a more inflammatory response during symptomatic infection; however, in general, these pathogens elicited a mild inflammatory response. PMID:21325554

  20. Fecal leukocytes in children infected with diarrheagenic Escherichia coli.

    PubMed

    Mercado, Erik H; Ochoa, Theresa J; Ecker, Lucie; Cabello, Martin; Durand, David; Barletta, Francesca; Molina, Margarita; Gil, Ana I; Huicho, Luis; Lanata, Claudio F; Cleary, Thomas G

    2011-04-01

    The purpose of this study was to determine the presence and quantity of fecal leukocytes in children infected with diarrheagenic Escherichia coli and to compare these levels between diarrhea and control cases. We analyzed 1,474 stool samples from 935 diarrhea episodes and 539 from healthy controls of a cohort study of children younger than 2 years of age in Lima, Peru. Stools were analyzed for common enteric pathogens, and diarrheagenic E. coli isolates were studied by a multiplex real-time PCR. Stool smears were stained with methylene blue and read by a blinded observer to determine the number of polymorphonuclear leukocytes per high-power field (L/hpf). Fecal leukocytes at >10 L/hpf were present in 11.8% (110/935) of all diarrheal episodes versus 1.1% (6/539) in controls (P < 0.001). Among stool samples with diarrheagenic E. coli as the only pathogen isolated (excluding coinfection), fecal leukocytes at >10 L/hpf were present in 8.5% (18/212) of diarrhea versus 1.3% (2/157) of control samples (P < 0.01). Ninety-five percent of 99 diarrheagenic E. coli diarrhea samples were positive for fecal lactoferrin. Adjusting for the presence of blood in stools, age, sex, undernutrition, and breastfeeding, enterotoxigenic E. coli (ETEC) isolation as a single pathogen, excluding coinfections, was highly associated with the presence of fecal leukocytes (>10 L/hpf) with an odds ratio (OR) of 4.1 (95% confidence interval [CI], 1.08 to 15.51; P < 0.05). Although diarrheagenic E. coli was isolated with similar frequencies in diarrhea and control samples, clearly it was associated with a more inflammatory response during symptomatic infection; however, in general, these pathogens elicited a mild inflammatory response. PMID:21325554

  1. 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.

  2. 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

  3. The glycosylation and structure of human serum IgA1, Fab, and Fc regions and the role of N-glycosylation on Fcα receptor interactions.

    PubMed

    Mattu, T S; Pleass, R J; Willis, A C; Kilian, M; Wormald, M R; Lellouch, A C; Rudd, P M; Woof, J M; Dwek, R A

    1998-01-23

    The human serum immunoglobulins IgG and IgA1 are produced in bone marrow and both interact with specific cellular receptors that mediate biological events. In contrast to IgA1, the glycosylation of IgG has been well characterized, and its interaction with various Fc receptors (Fc Rs) has been well studied. In this paper, we have analyzed the glycosylation of IgA1 and IgA1 Fab and Fc as well as three recombinant IgA1 molecules, including two N-glycosylation mutants. Amino acid sequencing data of the IgA1 Fc O-glycosylated hinge region indicated that O-glycans are located at Thr228, Ser230, and Ser232, while O-glycan sites at Thr225 and Thr236 are partially occupied. Over 90% of the N-glycans in IgA1 were sialylated, in contrast to IgG, where < 10% contain sialic acid. This paper contains the first report of Fab glycosylation in IgA1, and (in contrast to IgG Fab, which contains only N-linked glycans) both N- and O-linked oligosaccharides were identified. Analysis of the N-glycans attached to recombinant IgA1 indicated that the Cα 2 N-glycosylation site contained mostly biantennary glycans, while the tailpiece site, absent in IgG, contained mostly triantennary structures. Further analysis of these data suggested that processing at one Fc N-glycosylation site affects the other. Neutrophil Fcα R binding studies, using recombinant IgA1, indicated that neither the tailpiece region nor the N-glycans in the C alpha 2 domain contribute to IgA1-neutrophil Fcα R binding. This contrasts with IgG, where removal of the Fc N-glycans reduces binding to the Fcγ R. The primary sequence and disulfide bond pattern of IgA1, together with the crystal structures of IgG1 Fc and mouse IgA Fab and the glycan sequencing data, were used to generate a molecular model of IgA1. As a consequence of both the primary sequence and S-S bond pattern, the N-glycans in IgA1 Fc are not confined within the inter-α-chain space. The accessibility of the Cα 2 N-glycans provides an explanation for the

  4. Putative suppressing effect of IgG Fc-conjugated haemagglutinin (HA) stalk of influenza virus H7N9 on the neutralizing immunogenicity of Fc-conjugated HA head: implication for rational design of HA-based influenza vaccines.

    PubMed

    He, B; Xia, S; Yu, F; Fu, Y; Li, W; Wang, Q; Lu, L; Jiang, S

    2016-02-01

    The emergence of influenza A H7N9 in infection has posed a great threat to public health globally. Poor immunogenicity of H7N9 haemagglutinin (HA) is a major obstacle to the development of an effective H7N9 vaccine. Here, we found that the vaccine containing the H7HA head conjugated with IgG Fc (Hd-Fc) induced strong neutralizing antibody responses and protection against H7N9 infection, whilst the Fc-conjugated H7HA stalk (St-Fc)-based vaccine could not induce neutralizing antibodies, although the St-Fc-immunized mice were partially protected. The vaccines containing the full-length extracellular domain of HA conjugated with Fc and the mixture of Hd-Fc plus St-Fc induced significantly lower neutralizing antibody and haemagglutination inhibition titres than the Hd-Fc-based vaccine. These results suggest that the St-Fc may have inhibitory effects on the neutralizing immunogenicity of Hd-Fc. Therefore, the neutralizing domain(s), such as the receptor-binding domain, in the HA head should be kept and the non-neutralizing domain(s) in the HA stalk with the ability to potentially suppress the neutralizing immunogenicity of HA head should be removed from Fc-conjugated HA-based influenza vaccines to increase the neutralizing antibody response. PMID:26653217

  5. 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

  6. 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

    Kovács, Miklós; Németh, Tamás; Jakus, Zoltán; Sitaru, Cassian; Simon, Edina; Futosi, Krisztina; Botz, Bálint; Helyes, Zsuzsanna; Lowell, Clifford A; Mócsai, Attila

    2014-09-22

    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

  7. Identification and characterization of a FcR homolog in an ectothermic vertebrate, the channel catfish (Ictalurus punctatus)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A Fc receptor homolog (IpFcRI)3, representing the first such receptor from an ectothermic vertebrate, has been identified in the channel catfish (Ictalurus punctatus). Mining of the catfish expressed sequence tag (EST) databases using mammalian FcR sequences for CD16, CD32, and CD64 resulted in the ...

  8. Allelic and copy-number variations of FcγRs affect granulocyte function and susceptibility for autoimmune blistering diseases.

    PubMed

    Recke, Andreas; Vidarsson, Gestur; Ludwig, Ralf J; Freitag, Miriam; Möller, Steffen; Vonthein, Reinhard; Schellenberger, Julia; Haase, Ozan; Görg, Siegfried; Nebel, Almut; Flachsbart, Friederike; Schreiber, Stefan; Lieb, Wolfgang; Gläser, Regine; Benoit, Sandrine; Sárdy, Miklós; Eming, Rüdiger; Hertl, Michael; Zillikens, Detlef; König, Inke R; Schmidt, Enno; Ibrahim, Saleh

    2015-07-01

    Low-affinity Fcγ receptors (FcγR) bridge innate and adaptive immune responses. In many autoimmune diseases, these receptors act as key mediators of the pathogenic effects of autoantibodies. Genes encoding FcγR exhibit frequent variations in sequence and gene copy number that influence their functional properties. FcγR variations also affect the susceptibility to systemic autoimmunity, e.g. systemic lupus erythematosus and rheumatoid arthritis. This raises the question whether FcγR variations are also associated with organ-specific autoimmunity, particularly autoantibody-mediated diseases, such as subepidermal autoimmune blistering diseases (AIBD). A multitude of evidence suggests a pathogenic role of neutrophil granulocyte interaction with autoantibodies via FcγR. In a two-stage study, we analyzed whether the FcγR genotype affects neutrophil function and mRNA expression, and consequently, bullous pemphigoid (BP) disease risk. We compared this to findings in pemphigus vulgaris/foliaceus (PV/PF), two Fc-independent AIBDs. Our results indicate that both allele and copy number variation of FcγR genes affect FcγR mRNA expression and reactive oxygen species (ROS) release by granulocytes. Susceptibility of BP was associated with FcγR genotypes that led to a decreased ROS release by neutrophils, indicating an unexpected protective role for these cells. BP and PV/PF differed substantially regarding the FcγR genotype association patterns, pointing towards different disease etiologies. PMID:26032265

  9. Serum IgE clearance is facilitated by human FcεRI internalization

    PubMed Central

    Greer, Alexandra M.; Wu, Nan; Putnam, Amy L.; Woodruff, Prescott G.; Wolters, Paul; Kinet, Jean-Pierre; Shin, Jeoung-Sook

    2014-01-01

    The high-affinity IgE receptor FcεRI is constitutively expressed in mast cells and basophils and is required for transmitting stimulatory signals upon engagement of IgE-bound allergens. FcεRI is also constitutively expressed in dendritic cells (DCs) and monocytes in humans; however, the specific functions of the FcεRI expressed by these cells are not completely understood. Here, we found that FcεRI expressed by human blood DC antigen 1–positive (BDCA1+) DCs and monocytes, but not basophils, traffics to endolysosomal compartments under steady-state conditions. Furthermore, IgE bound to FcεRI on BDCA1+ DCs was rapidly endocytosed, transported to the lysosomes, and degraded in vitro. IgE injected into mice expressing human FcεRIα (FCER1A-Tg mice) was endocytosed by conventional DCs and monocytes, and endocytosis was associated with rapid clearance of circulating IgE from these mice. Importantly, this rapid IgE clearance was dependent on monocytes or DCs but not basophils. These findings strongly suggest that constitutive internalization of human FcεRI by DCs and monocytes distinctively contributes to serum IgE clearance. PMID:24569373

  10. Functional and clinical consequences of Fc receptor polymorphic and copy number variants

    PubMed Central

    Bournazos, S; Woof, J M; Hart, S P; Dransfield, I

    2009-01-01

    Receptors for immunoglobulins (Fc receptors) play a central role during an immune response, as they mediate the specific recognition of antigens of almost infinite diversity by leucocytes, thereby linking the humoral and cellular components of immunity. Indeed, engagement of Fc receptors by immunoglobulins initiates a range of immunoregulatory processes that might also play a role in disease pathogenesis. In the circulation, five main types of immunoglobulins (Ig) exist – namely IgG, IgA, IgE, IgM and IgD and receptors with the ability to recognize and bind to IgG (Fcγ receptor family), IgE (FcεRI and CD23), IgA (CD89; Fcα/µR) and IgM (Fcα/µR) have been identified and characterized. However, it is astonishing that nearly all the known human Fc receptors display extensive genetic variation with clear implications for their function, thus representing a substantial genetic risk factor for the pathogenesis of a range of chronic inflammatory disorders. PMID:19604264

  11. 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

  12. 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.

  13. Ebola virus glycoprotein Fc fusion protein confers protection against lethal challenge in vaccinated mice

    PubMed Central

    Konduru, Krishnamurthy; Bradfute, Steven B.; Jacques, Jerome; Manangeeswaran, Mohanraj; Nakamura, Siham; Morshed, Sufi; Wood, Steven C.; Bavari, Sina

    2011-01-01

    Ebola virus is a Filoviridae that causes hemorrhagic fever in humans and induces high morbidity and mortality rates. Filoviruses are classified as "Category A bioterrorism agents", and currently there are no licensed therapeutics or vaccines to treat and prevent infection. The Filovirus glycoprotein (GP) is sufficient to protect individuals against infection, and several vaccines based on GP are under development including recombinant adenovirus, parainfluenza virus, Venezuelan equine encephalitis virus, vesicular stomatitis virus (VSV) and virus-like particles. Here we describe the development of a GP Fc fusion protein as a vaccine candidate. We expressed the extracellular domain of the Zaire Ebola virus (ZEBOV) GP fused to the Fc fragment of human IgG1 (ZEBOVGP-Fc) in mammalian cells and showed that GP undergoes the complex furin cleavage and processing observed in the native membrane-bound GP. Mice immunized with ZEBOVGP-Fc developed T-cell immunity against ZEBOV GP and neutralizing antibodies against replication-competent VSV-G deleted recombinant VSV containing ZEBOV GP. The ZEBOVGP-Fc vaccinated mice were protected against challenge with a lethal dose of ZEBOV. These results show that vaccination with the ZEBOVGP-Fc fusion protein alone without the need of a viral vector or assembly into virus-like particles is sufficient to induce protective immunity against ZEBOV in mice. Our data suggested that Filovirus GP Fc fusion proteins could be developed as a simple, safe, efficacious, and cost effective vaccine against Filovirus infection for human use. PMID:21329775

  14. Human IgG Fc promotes expression, secretion and immunogenicity of enterovirus 71 VP1 protein

    PubMed Central

    Xu, Juan; Zhang, Chunhua

    2016-01-01

    Abstract 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.

  15. (Some) Cellular Mechanisms Influencing the Transcription of Human Endogenous Retrovirus, HERV-Fc1

    PubMed Central

    Laska, Magdalena Janina; Nissen, Kari Konstantin; Nexø, Bjørn Andersen

    2013-01-01

    DNA methylation and histone acetylation are epigenetic modifications that act as regulators of gene expression. DNA methylation is considered an important mechanism for silencing of retroelements in the mammalian genome. However, the methylation of human endogenous retroviruses (HERVs) is not well investigated. The aim of this study was to investigate the transcriptional potential of HERV-Fc1 proviral 5′LTR in more detail, and examined the specific influence of CpG methylation on this LTR in number of cell lines. Specifically, the role of demethylating chemicals e.g. 5-aza-2′ deoxycytidine and Trichostatin-A, in inducing or reactivating expression of HERV-Fc1 specific sequences and the mechanisms were investigated. In our present study, 5-aza-dC is shown to be a powerful inducer of HERV-Fc1, and at the same time it strongly inhibits methylation of DNA. Treatment with this demethylating agent 5-aza-dC, results in significantly increased levels of HERV-Fc1 expression in cells previously not expressing HERV-Fc1, or with a very low expression level. The extent of expression of HERV-Fc1 RNAs precisely correlates with the apparent extent of demethylation of the related DNA sequences. In conclusion, the results suggest that inhibition of DNA methylation/histone deacetylase can interfere with gene silencing mechanisms affecting HERV-Fc1 expression in human cells. PMID:23382858

  16. Characterisation of a Novel Fc Conjugate of Macrophage Colony-stimulating Factor

    PubMed Central

    Gow, Deborah J; Sauter, Kristin A; Pridans, Clare; Moffat, Lindsey; Sehgal, Anuj; Stutchfield, Ben M; Raza, Sobia; Beard, Philippa M; Tsai, Yi Ting; Bainbridge, Graeme; Boner, Pamela L; Fici, Greg; Garcia-Tapia, David; Martin, Roger A; Oliphant, Theodore; Shelly, John A; Tiwari, Raksha; Wilson, Thomas L; Smith, Lee B; Mabbott, Neil A; Hume, David A

    2014-01-01

    We have produced an Fc conjugate of colony-stimulating factor (CSF) 1 with an improved circulating half-life. CSF1-Fc retained its macrophage growth-promoting activity, and did not induce proinflammatory cytokines in vitro. Treatment with CSF1-Fc did not produce adverse effects in mice or pigs. The impact of CSF1-Fc was examined using the Csf1r-enhanced green fluorescent protein (EGFP) reporter gene in MacGreen mice. Administration of CSF1-Fc to mice drove extensive infiltration of all tissues by Csf1r-EGFP positive macrophages. The main consequence was hepatosplenomegaly, associated with proliferation of hepatocytes. Expression profiles of the liver indicated that infiltrating macrophages produced candidate mediators of hepatocyte proliferation including urokinase, tumor necrosis factor, and interleukin 6. CSF1-Fc also promoted osteoclastogenesis and produced pleiotropic effects on other organ systems, notably the testis, where CSF1-dependent macrophages have been implicated in homeostasis. However, it did not affect other putative CSF1 targets, notably intestine, where Paneth cell numbers and villus architecture were unchanged. CSF1 has therapeutic potential in regenerative medicine in multiple organs. We suggest that the CSF1-Fc conjugate retains this potential, and may permit daily delivery by injection rather than continuous infusion required for the core molecule. PMID:24962162

  17. Modulation of leukocyte adhesion in rat mesenteric venules by aspirin and salicylate.

    PubMed

    Asako, H; Kubes, P; Wallace, J; Wolf, R E; Granger, D N

    1992-07-01

    Erythrocyte velocity, vessel diameter, leukocyte rolling velocity, and number of adherent and emigrated leukocytes were measured in postcapillary venules both before and during superfusion of rat mesentery with either aspirin or sodium salicylate. In some experiments, animals were treated with either a leukotriene (LT)-synthesis inhibitor (L-663,536), an LTD4 antagonist (MK-571), an LTB4 antagonist (SC-41930), misoprostol, or prostaglandin (PG) I2, then the aspirin protocol was repeated. Superfusion of aspirin but not sodium salicylate resulted in increased leukocyte adherence and a reduced leukocyte rolling velocity but did not affect leukocyte emigration. Aspirin-induced leukocyte adhesion was effectively prevented by the LT-synthesis inhibitor and LTB4 antagonist but not by the LTD4 antagonist. Misoprostol and PGI2 also prevented the aspirin-induced adhesion responses. Superfusion of the mesentery with either platelet-activating factor (PAF) or LTB4 enhanced leukocyte adherence and emigration while reducing leukocyte rolling velocity. Sodium salicylate prevented all of the adhesion responses elicited by LTB4. Although salicylate did not affect the PAF-induced leukocyte adherence and rolling responses, it completely prevented the increased leukocyte emigration. These results indicate that aspirin promotes, whereas sodium salicylate inhibits, leukocyte-endothelial cell adhesive interactions at therapeutically relevant concentrations. PMID:1319367

  18. 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.

  19. 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

  20. n-3 Polyunsaturated fatty acids inhibit Fc ε receptor I-mediated mast cell activation.

    PubMed

    Wang, Xiaofeng; Ma, David W L; Kang, Jing X; Kulka, Marianna

    2015-12-01

    In vivo models show that n-3 polyunsaturated fatty acids (PUFA) inhibit some of the processes associated with allergic inflammation but the direct effect of n-3 PUFA on mast cells, the major effector cells in allergy, is poorly understood. We sought to determine the effect and mechanism of n-3 PUFA on Fc ε receptor I (FcεRI)-mediated signal transduction and mast cell activation. Bone marrow-derived mast cells (BMMC) were differentiated from bone marrow obtained from C57BL/6 wild-type (WT) and fat-1 transgenic mice. The fat-1 mice express fatty acid n-3 desaturase and produce endogenous n-3 PUFA. For comparison, exogenous n-3 PUFA were supplemented to WT BMMC and human mast cell (LAD2) cultures. Fat-1 BMMC released less β-hexosaminidase (β-hex) and cysteinyl leukotrienes and produced less tumor necrosis factor and chemokine (C-C motif) ligand 2. n-3 PUFA supplementation reduced LAD2 and BMMC degranulation (β-hex release) following FcεRI activation. Fat-1 BMMC expressed less constitutive Lyn and linker of activated T cells (LAT), and FcεRI-mediated phosphorylation of Lyn, spleen tyrosine kinase and LAT were reduced in fat-1 BMMC. Although the expression of surface and whole cell FcεRI was similar in WT and fat-1 BMMC, unstimulated fat-1 BMMC showed reduced FcεRI localization to lipid rafts, and stimulation with antigen resulted in aberrant FcεRI shuttling to the rafts. Our results show that n-3 PUFA suppress FcεRI-mediated activation of mast cells, which results in reduced mediator release. This effect is associated with a decrease in LAT and Lyn expression as well as abnormal shuttling of FcεRI to lipid rafts. PMID:26363927

  1. FcRn-mediated antibody transport across epithelial cells revealed by electron tomography.

    PubMed

    He, Wanzhong; Ladinsky, Mark S; Huey-Tubman, Kathryn E; Jensen, Grant J; McIntosh, J Richard; Björkman, Pamela J

    2008-09-25

    The neonatal Fc receptor (FcRn) transports maternal IgG across epithelial barriers, thereby providing the fetus or newborn with humoral immunity before its immune system is fully functional. In newborn rats, FcRn transfers IgG from milk to blood by apical-to-basolateral transcytosis across intestinal epithelial cells. The pH difference between the apical (pH 6.0-6.5) and basolateral (pH 7.4) sides of intestinal epithelial cells facilitates the efficient unidirectional transport of IgG, because FcRn binds IgG at pH 6.0-6.5 but not at pH 7 or more. As milk passes through the neonatal intestine, maternal IgG is removed by FcRn-expressing cells in the proximal small intestine (duodenum and jejunum); remaining proteins are absorbed and degraded by FcRn-negative cells in the distal small intestine (ileum). Here we use electron tomography to make jejunal transcytosis visible directly in space and time, developing new labelling and detection methods to map individual nanogold-labelled Fc within transport vesicles and simultaneously to characterize these vesicles by immunolabelling. Combining electron tomography with a non-perturbing endocytic label allowed us to conclusively identify receptor-bound ligands, resolve interconnecting vesicles, determine whether a vesicle was microtubule-associated, and accurately trace FcRn-mediated transport of IgG. Our results present a complex picture in which Fc moves through networks of entangled tubular and irregular vesicles, only some of which are microtubule-associated, as it migrates to the basolateral surface. New features of transcytosis are elucidated, including transport involving multivesicular body inner vesicles/tubules and exocytosis through clathrin-coated pits. Markers for early, late and recycling endosomes each labelled vesicles in different and overlapping morphological classes, revealing spatial complexity in endo-lysosomal trafficking. PMID:18818657

  2. FcRn-mediated antibody transport across epithelial cells revealed by electron tomography

    PubMed Central

    He, Wanzhong; Ladinsky, Mark S.; Huey-Tubman, Kathryn E.; Jensen, Grant J.; McIntosh, J. Richard; Björkman, Pamela J.

    2009-01-01

    The neonatal Fc receptor (FcRn) transports maternal IgG across epithelial barriers1,2, thereby providing the fetus or newborn with humoral immunity before its immune system is fully functional. In newborn rodents, FcRn transfers IgG from milk to blood by apical-to-basolateral transcytosis across intestinal epithelial cells. The pH difference between the apical (pH 6.0-6.5) and basolateral (pH 7.4) sides of intestinal epithelial cells facilitates efficient unidirectional transport of IgG, since FcRn binds IgG at pH 6.0-6.5 but not pH ≥7 1,2. As milk passes through the neonatal intestine, maternal IgG is removed by FcRn-expressing cells in the proximal small intestine (duodenum, jejunum); remaining proteins are absorbed and degraded by FcRn-negative cells in the distal small intestine (ileum)3-6. We used electron tomography to directly visualize jejunal transcytosis in space and time, developing new labeling and detection methods to map individual nanogold-labeled Fc within transport vesicles7 and to simultaneously characterize these vesicles by immunolabeling. Combining electron tomography with a non-perturbing endocytic label allowed us to conclusively identify receptor-bound ligands, resolve interconnecting vesicles, determine if a vesicle was microtubule-associated, and accurately trace FcRn-mediated transport of IgG. Our results present a complex picture in which Fc moved through networks of entangled tubular and irregular vesicles, only some of which were microtubule-associated, as it migrated to the basolateral surface. New features of transcytosis were elucidated, including transport involving multivesicular body inner vesicles/tubules and exocytosis via clathrin-coated pits. Markers for early, late, and recycling endosomes each labeled vesicles in different and overlapping morphological classes, revealing unexpected spatial complexity in endo-lysosomal trafficking. PMID:18818657

  3. 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.

  4. Big insights from small volumes: deciphering complex leukocyte behaviors using microfluidics.

    PubMed

    Irimia, Daniel; Ellett, Felix

    2016-08-01

    Inflammation is an indispensable component of the immune response, and leukocytes provide the first line of defense against infection. Although the major stereotypic leukocyte behaviors in response to infection are well known, the complexities and idiosyncrasies of these phenotypes in conditions of disease are still emerging. Novel tools are indispensable for gaining insights into leukocyte behavior, and in the past decade, microfluidic technologies have emerged as an exciting development in the field. Microfluidic devices are readily customizable, provide tight control of experimental conditions, enable high precision of ex vivo measurements of individual as well as integrated leukocyte functions, and have facilitated the discovery of novel leukocyte phenotypes. Here, we review some of the most interesting insights resulting from the application of microfluidic approaches to the study of the inflammatory response. The aim is to encourage leukocyte biologists to integrate these new tools into increasingly more sophisticated experimental designs for probing complex leukocyte functions. PMID:27194799

  5. Maximal element theorems in product FC-spaces and generalized games

    NASA Astrophysics Data System (ADS)

    Ding, Xie Ping

    2005-05-01

    Let I be a finite or infinite index set, X be a topological space and (Yi,{[phi]Ni})i[set membership, variant]I be a family of finitely continuous topological spaces (in short, FC-space). For each i[set membership, variant]I, let be a set-valued mapping. Some existence theorems of maximal elements for the family {Ai}i[set membership, variant]I are established under noncompact setting of FC-spaces. As applications, some equilibrium existence theorems for generalized games with fuzzy constraint correspondences are proved in noncompact FC-spaces. These theorems improve, unify and generalize many important results in recent literature.

  6. 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.

  7. Requirement for Fc Effector Mechanisms in the APOBEC3/Rfv3-Dependent Neutralizing Antibody Response

    PubMed Central

    Halemano, Kalani; Barrett, Bradley S.; Heilman, Karl J.; Morrison, Thomas E.

    2015-01-01

    Antiretroviral neutralizing antibody (NAb) responses are often evaluated in the absence of Fc-dependent immune effectors. In murine Friend retrovirus infection, Apobec3/Rfv3 promotes a potent polyclonal NAb response. Here, we show that the Apobec3/Rfv3-dependent NAb response correlated with virus-specific IgG2 titers and that the in vivo neutralization potency of Apobec3/Rfv3-resistant antisera was dependent on activating Fcγ receptors but not complement. The data strengthen retroviral vaccine strategies aimed at eliciting NAbs that activate specific Fcγ receptors. PMID:25589647

  8. 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

  9. Blockade of immunoregulatory Fc-signalling by HIV peptides: oligopeptides from HIV gp120 and gp41 bind the Fc portion of IgG and increase the in vitro anti-ssDNA response.

    PubMed Central

    Rahimpour, R; Anderson, C C; Sinclair, N R

    1993-01-01

    Concomitant ligation of antigen receptors with Fc-receptors negatively signals B cells. Antibodies to the Fc portion of IgG prevent this negative Fc-signalling, provided that these antibodies do not emit Fc signals. Prevention of Fc signals leads to augmented antibody responses to self and foreign antigens, and reduces the requirement for T cells by 10- to 100-fold in T cell-dependent antibody responses. In ELISA assays, peptides from conserved portions of the glycoproteins, HIV-1 gp120 or gp41 from HIV-1 and HIV-2 bind to the Fc portion of IgG, but do not bind the F(ab')2 portion of IgG. HIV-derived peptides, which bind to the Fc portion of IgG, augment the antibody-forming cell response to single-stranded (ss)DNA. The spontaneous response to ssDNA using spleen cells from young mice, and the response in the presence of exogenous DNA using spleen cells from old mice, are augmented to the greatest extent. These results demonstrate that HIV peptides bind to the Fc portion of IgG and augment immune responses to DNA; they suggest the possibility that blockade of the Fc portion of IgG antibodies is associated with a reduction in Fc-mediated regulation of anti-self responses. Blockade of regulatory Fc-signalling may account for increased circulating immunoglobulins and autoantibodies in clinical AIDS. PMID:8403512

  10. 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. PMID:26076445

  11. 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

  12. 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

  13. 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. PMID:27174242

  14. Myxoma and Vaccinia Viruses Bind Differentially to Human Leukocytes

    PubMed Central

    Chan, Winnie M.; Bartee, Eric C.; Moreb, Jan S.; Dower, Ken; Connor, John H.

    2013-01-01

    Myxoma virus (MYXV) and vaccinia virus (VACV), two distinct members of the family Poxviridae, are both currently being developed as oncolytic virotherapeutic agents. Recent studies have demonstrated that ex vivo treatment with MYXV can selectively recognize and kill contaminating cancerous cells from autologous bone marrow transplants without perturbing the engraftment of normal CD34+ hematopoietic stem and progenitor cells. However, the mechanism(s) by which MYXV specifically recognizes and eliminates the cancer cells in the autografts is not understood. While little is known about the cellular attachment factor(s) exploited by MYXV for entry into any target cells, VACV has been shown to utilize cell surface glycosaminoglycans such as heparan sulfate (HS), the extracellular matrix protein laminin, and/or integrin β1. We have constructed MYXV and VACV virions tagged with the Venus fluorescent protein and compared their characteristics of binding to various human cancer cell lines as well as to primary human leukocytes. We report that the binding of MYXV or VACV to some adherent cell lines could be partially inhibited by heparin, but laminin blocked only VACV binding. In contrast to cultured fibroblasts, the binding of MYXV and VACV to a wide spectrum of primary human leukocytes could not be competed by either HS or laminin. Additionally, MYXV and VACV exhibited very different binding characteristics against certain select human leukocytes, suggesting that the two poxviruses utilize different cell surface determinants for the attachment to these cells. These results indicate that VACV and MYXV can exhibit very different oncolytic tropisms against some cancerous human leukocytes. PMID:23388707

  15. 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

  16. 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.

  17. Indium-111 leukocyte localization in infected prosthetic graft

    SciTech Connect

    Purnell, G.L.; Walker, C.W.; Allison, J.W.; Dalrymple, G.V. )

    1990-08-01

    Infective endocarditis can be difficult to prove, even in the face of strong clinical suspicion. A case in which standard methods of diagnosis failed to demonstrate endocarditis in a patient with recurrent Staphylococcus aureus bacteremia and porcine aortic valve is reported. An In-111 labelled leukocyte SPECT study demonstrated uptake in the aortic root and leaflets, and autopsy demonstrated vegetations on the leaflets. In-111 may prove useful in demonstrating endocarditis in patients with prosthetic valve infection.

  18. 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. PMID:26551552

  19. Leukocyte recovery from umbilical cord blood by poligeline.

    PubMed

    Perutelli, P; Catellani, S

    1999-02-01

    Umbilical cord blood (UCB) collected at delivery is a source of transplantable stem/progenitor cells; it represents an alternative to bone marrow to restore hematopoiesis in patients affected by malignant and non-malignant disease. Therefore, large-scale UCB banks would be a natural complement to bone marrow donor registries. Storage of unmanipulated whole UCB units requires a great number of liquid nitrogen containers. Separation of leukocytes allows UCB storage in smaller space, thus lowering banking costs; unfortunately, UCB processing may cause significant losses of stem cells. We report about the use of poligeline to remove erythrocytes from UCB units. After erythrocyte sedimentation at 1xg (30' or 40') or 50xg, leukocyte-rich supernatant was collected and centrifuged to recover the leukocyte pool in view of stem cell transplantation. Erythrocyte depletion was always satisfactory, ranging from 82.6% to 88.9%, but 1xg sedimentation for 40' enabled us to achieve the best CD34+ cell recovery (mean value 80.5%). The proposed UCB-processing method allowed us to lower the final sample volume down to 1/10 of the initial one, in this way making UCB banking feasible. Erythrocyte depletion took place directly in the collection bag, thus reducing microbial contamination risk. PMID:10193639

  20. 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

  1. 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

  2. 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. PMID:26408877

  3. 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.

  4. Influence of tetracyclines on human polymorphonuclear leukocyte function.

    PubMed Central

    Glette, J; Sandberg, S; Hopen, G; Solberg, C O

    1984-01-01

    Low concentrations of oxytetracycline, doxycycline, or minocycline (less than 10 micrograms/ml) did not influence in vitro polymorphonuclear leukocyte random migration, chemiluminescence, or glucose oxidation. At high concentrations of doxycycline or minocycline (greater than 10 micrograms/ml), chemiluminescence and glucose oxidation were impaired. High concentrations of doxycycline also reduced random migration. Oxytetracycline did not influence these functions in concentrations up to 100 micrograms/ml. The inhibiting effect of doxycycline and minocycline was abolished when 4 mM Mg2+ was added to the reaction mixture, and 4 mM Ca2+ partly restored minocycline-inhibited polymorphonuclear leukocyte functions. This indicates that the major effect of tetracyclines on in vitro polymorphonuclear leukocyte functions is mediated by their divalent cation chelating effect and that the results of in vitro experiments are highly dependent on the concentration of divalent cations in the reaction mixtures. The difference between the tetracyclines may be due to differences in lipid solubility, with solubility being highest for minocycline and lowest for oxytetracycline, or to different divalent cation chelating ability. PMID:6721468

  5. Tracking flow of leukocytes in blood for drug analysis

    NASA Astrophysics Data System (ADS)

    Basharat, Arslan; Turner, Wesley; Stephens, Gillian; Badillo, Benjamin; Lumpkin, Rick; Andre, Patrick; Perera, Amitha

    2011-03-01

    Modern microscopy techniques allow imaging of circulating blood components under vascular flow conditions. The resulting video sequences provide unique insights into the behavior of blood cells within the vasculature and can be used as a method to monitor and quantitate the recruitment of inflammatory cells at sites of vascular injury/ inflammation and potentially serve as a pharmacodynamic biomarker, helping screen new therapies and individualize dose and combinations of drugs. However, manual analysis of these video sequences is intractable, requiring hours per 400 second video clip. In this paper, we present an automated technique to analyze the behavior and recruitment of human leukocytes in whole blood under physiological conditions of shear through a simple multi-channel fluorescence microscope in real-time. This technique detects and tracks the recruitment of leukocytes to a bioactive surface coated on a flow chamber. Rolling cells (cells which partially bind to the bioactive matrix) are detected counted, and have their velocity measured and graphed. The challenges here include: high cell density, appearance similarity, and low (1Hz) frame rate. Our approach performs frame differencing based motion segmentation, track initialization and online tracking of individual leukocytes.

  6. 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.

  7. 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. PMID:27115171

  8. Fc-optimized NKG2D-Fc constructs induce NK cell antibody-dependent cellular cytotoxicity against breast cancer cells independently of HER2/neu expression status.

    PubMed

    Raab, Stefanie; Steinbacher, Julia; Schmiedel, Benjamin J; Kousis, Philaretos C; Steinle, Alexander; Jung, Gundram; Grosse-Hovest, Ludger; Salih, Helmut R

    2014-10-15

    The ability of NK cells to mediate Ab-dependent cellular cytotoxicity (ADCC) largely contributes to the clinical success of antitumor Abs, including trastuzumab, which is approved for the treatment of breast cancer with HER2/neu overexpression. Notably, only ∼25% of breast cancer patients overexpress HER2/neu. Moreover, HER2/neu is expressed on healthy cells, and trastuzumab application is associated with side effects. In contrast, the ligands of the activating immunoreceptor NKG2D (NKG2DL) are selectively expressed on malignant cells. In this study, we took advantage of the tumor-associated expression of NKG2DL by using them as target Ags for NKG2D-IgG1 fusion proteins optimized by amino acid exchange S239D/I332E in their Fc part. Compared to constructs with wild-type Fc parts, fusion proteins carrying the S239D/I332E modification (NKG2D-Fc-ADCC) mediated highly enhanced degranulation, ADCC, and IFN-γ production of NK cells in response to breast cancer cells. NKG2D-Fc-ADCC substantially enhanced NK reactivity also against HER2/neu-low targets that were unaffected by trastuzumab, as both compounds mediated their immunostimulatory effects in strict dependence of target Ag expression levels. Thus, in line with the hierarchically organized potential of the various activating receptors governing NK reactivity and due to its highly increased affinity to CD16, NKG2D-Fc-ADCC potently enhances NK cell reactivity despite the inevitable reduction of activating signals upon binding to NKG2DL. Due to the tumor-restricted expression of NKG2DL, NKG2D-Fc-ADCC may constitute an attractive means for immunotherapy especially of HER2/neu-low or -negative breast cancer. PMID:25217158

  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. 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 ...

  11. 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.

  12. Development and Characterization of Monoclonal Antibodies Specific for Mouse and Human Fcγ Receptors.

    PubMed

    Tutt, Alison L; James, Sonya; Laversin, Stéphanie A; Tipton, Thomas R W; Ashton-Key, Margaret; French, Ruth R; Hussain, Khiyam; Vaughan, Andrew T; Dou, Lang; Earley, Alexander; Dahal, Lekh N; Lu, Chen; Dunscombe, Melanie; Chan, H T Claude; Penfold, Christine A; Kim, Jinny H; Potter, Elizabeth A; Mockridge, C Ian; Roghanian, Ali; Oldham, Robert J; Cox, Kerry L; Lim, Sean H; Teige, Ingrid; Frendéus, Bjorn; Glennie, Martin J; Beers, Stephen A; Cragg, Mark S

    2015-12-01

    FcγRs are key regulators of the immune response, capable of binding to the Fc portion of IgG Abs and manipulating the behavior of numerous cell types. Through a variety of receptors, isoforms, and cellular expression patterns, they are able to fine-tune and direct appropriate responses. Furthermore, they are key determinants of mAb immunotherapy, with mAb isotype and FcγR interaction governing therapeutic efficacy. Critical to understanding the biology of this complex family of receptors are reagents that are robust and highly specific for each receptor. In this study, we describe the development and characterization of mAb panels specific for both mouse and human FcγR for use in flow cytometry, immunofluorescence, and immunocytochemistry. We highlight key differences in expression between the two species and also patterns of expression that will likely impact on immunotherapeutic efficacy and translation of therapeutic agents from mouse to clinic. PMID:26512139

  13. 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

  14. 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

  15. 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

  16. Influence of delivery on numbers of leukocytes, leukocyte subpopulations, and hematopoietic progenitor cells in human umbilical cord blood.

    PubMed

    Lim, F T; van Winsen, L; Willemze, R; Kanhai, H H; Falkenburg, J H

    1994-01-01

    Human umbilical cord blood (UCB) may be used as an alternative source of bone marrow repopulating cells in allogeneic bone marrow transplantation. The quality and quantity of UCB harvests for transplantation is affected by several factors. In this study we analyzed the influence of delivery, in particular stress during delivery, on the numbers of leukocytes and leukocyte subsets in UCB. Four groups of women with different types of deliveries were included in the study, and from each group samples of UCB were analyzed. Blood samples from healthy adults were used as control. In UCB there was a higher absolute number of leukocytes than in peripheral blood (PB). UCB leukocytes were highest after deliveries with a prolonged second stage of labor, which was mainly due to granulocytosis. The percentage of T cells in UCB was lower than in PB, in particular when stress during delivery was higher. In all groups, however, the absolute concentration of T cells per milliliter of UCB was higher than in adult PB. The differences in T cells in stressful deliveries were mainly due to a relative decrease in CD3+/CD4+ cells in UCB. The relative frequency and absolute concentration of the CD56+ cell population in UCB was higher than in PB, which was mostly due to an increase of CD2-/CD56+ cells, in particular in stressful deliveries. The absolute number of CD34+ cells as well as hematopoietic progenitor cells as determined in semisolid medium cultures was high in UCB and was increased in cases of prolonged secondary stage of labor. This study demonstrates that the quality of UCB transplants is influenced by the course of delivery, in particular by stress during delivery. PMID:7749120

  17. Insights from Fc receptor biology: a route to improved antibody reagents.

    PubMed

    Woof, Jenny M

    2012-01-01

    Fc receptors and their interaction with antibodies will be a major theme at the forthcoming FASEB Science Research Conference on Immunoreceptors to be held in Snowmass this July (details available at www.faseb.org/src/home.aspx, follow the tabs for Immunoreceptors). Since its inception in the mid 1980s, this meeting series has maintained a focus on Fc receptors, and this year's meeting will be no exception. PMID:22531437

  18. Insights from Fc receptor biology: A route to improved antibody reagents

    PubMed Central

    2012-01-01

    Fc receptors and their interaction with antibodies will be a major theme at the forthcoming FASEB Science Research Conference on Immunoreceptors to be held in Snowmass this July (details available at www.faseb.org/src/home.aspx, follow the tabs for Immunoreceptors). Since its inception in the mid 1980s, this meeting series has maintained a focus on Fc receptors, and this year’s meeting will be no exception. PMID:22531437

  19. Enhancement of resting-state fcMRI networks by prior sensory stimulation.

    PubMed

    Li, Chenxuan; Li, Zhixin; Ward, B Douglas; Dwinell, Melinda R; Lombard, Julian H; Hudetz, Anthony G; Pawela, Christopher P

    2014-11-01

    It is important to consider the effect of a previous experimental condition when analyzing resting-state functional connectivity magnetic resonance imaging (fcMRI) data. In this work, a simple sensory stimulation functional MRI (fMRI) experiment was conducted between two resting-state fcMRI acquisitions in anesthetized rats using a high-field small-animal MR scanner. Previous human studies have reported fcMRI network alteration by prior task/stimulus utilizing similar experimental paradigms. An anesthetized rat preparation was used to test whether brain regions with higher level functions are involved in post-task/stimulus fcMRI network alteration. We demonstrate significant fcMRI enhancement poststimulation in the sensory cortical, limbic, and insular brain regions in rats. These brain regions have been previously implicated in vigilance and anesthetic arousal networks. We tested their experimental paradigm in several inbred strains of rats with known phenotypic differences in anesthetic susceptibility and cerebral vascular function. Brown Norway (BN), Dahl Salt-Sensitive (SS), and consomic SSBN13 strains were tested. We have previously shown significant differences in blood oxygen level-dependent fMRI activity and fcMRI networks across these strains. Here we report statistically significant interstrain differences in regional fcMRI poststimulation enhancement. In the SS strain, poststimulation enhancement occurred in posterior sensory and limbic cortical brain regions. In the BN strain, poststimulation enhancement appeared in anterior cingulate and subcortical limbic brain regions. These results imply that a prior condition has a significant impact on fcMRI networks that depend on intersubject difference in genetics and physiology. PMID:25387238

  20. Enhancement of Resting-State fcMRI Networks by Prior Sensory Stimulation

    PubMed Central

    Li, Chenxuan; Li, Zhixin; Ward, B. Douglas; Dwinell, Melinda R.; Lombard, Julian H.; Hudetz, Anthony G.

    2014-01-01

    Abstract It is important to consider the effect of a previous experimental condition when analyzing resting-state functional connectivity magnetic resonance imaging (fcMRI) data. In this work, a simple sensory stimulation functional MRI (fMRI) experiment was conducted between two resting-state fcMRI acquisitions in anesthetized rats using a high-field small-animal MR scanner. Previous human studies have reported fcMRI network alteration by prior task/stimulus utilizing similar experimental paradigms. An anesthetized rat preparation was used to test whether brain regions with higher level functions are involved in post-task/stimulus fcMRI network alteration. We demonstrate significant fcMRI enhancement poststimulation in the sensory cortical, limbic, and insular brain regions in rats. These brain regions have been previously implicated in vigilance and anesthetic arousal networks. We tested their experimental paradigm in several inbred strains of rats with known phenotypic differences in anesthetic susceptibility and cerebral vascular function. Brown Norway (BN), Dahl Salt-Sensitive (SS), and consomic SSBN13 strains were tested. We have previously shown significant differences in blood oxygen level-dependent fMRI activity and fcMRI networks across these strains. Here we report statistically significant interstrain differences in regional fcMRI poststimulation enhancement. In the SS strain, poststimulation enhancement occurred in posterior sensory and limbic cortical brain regions. In the BN strain, poststimulation enhancement appeared in anterior cingulate and subcortical limbic brain regions. These results imply that a prior condition has a significant impact on fcMRI networks that depend on intersubject difference in genetics and physiology. PMID:25387238

  1. 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

  2. Transient expression of Fc-fused human glycoprotein 130 in Expi293F suspension cells.

    PubMed

    Zhao, Xiaozhi; Chen, Wei; Ge, Liyuan; Jiang, Wei; Tang, Bo; Zhang, Qing; Xu, Xiaoyu; Wang, Chong; Cao, Lin; Guo, Hongqian

    2016-08-01

    Human glycoprotein 130 (gp130) is a signal-transducing receptor for interleukin 6 (IL-6), whose signaling plays a critical role in chronic inflammation and cancer. The soluble form of gp130 specifically inhibits IL-6 trans-signaling. However, achieving high-level expression of a large glycoprotein such as gp130 is difficult. Here, we designed and constructed one Fc-gp130-pcDNA mammalian expression vector, with the mouse IgG2a Fc fragment added to the N-terminus of human gp130, which greatly increased the secretion of recombinant gp130 protein from Expi293F suspension cells. Recombinant fusion Fc-gp130 was easily and efficiently purified from the supernatant of transfected cells by one-step affinity chromatography. Moreover, Fc-gp130 could automatically form dimers by the disulfide bond. Fc-gp130 was confirmed as a more efficient IL-6 trans-signaling blocker by its higher biological activity against signal transducer and activator of transcription 3 (STAT3). This purified active Fc-gp130 could be used to develop valuable therapeutic agents against inflammatory diseases and cancers. PMID:27113713

  3. FC-NIRS: A Functional Connectivity Analysis Tool for Near-Infrared Spectroscopy Data

    PubMed Central

    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

  4. Method for creating gas standards form liquid HFE-7100 and FC-72.

    SciTech Connect

    White, Michael K.; Brown, Jason R.; Thornberg, Steven Michael; Hochrein, James Michael; Irwin, Adriane Nadine

    2007-07-01

    HFE-7100 and FC-72 fluorinert are two fluids used during weapon component manufacturing. HFE-7100 is a solvent used in the cleaning of parts, and FC-72 is the blowing agent of a polymeric removable foam. The presence of either FC-72 or HFE-7100 gas in weapon components can provide valuable information as to the stability of the materials. Therefore, gas standards are needed so HFE-7100 and FC-72 gas concentrations can be accurately measured. There is no current established procedure for generating gas standards of either HFE-7100 or FC-72. This report outlines the development of a method to generate gas standards ranging in concentration from 0.1 ppm to 10% by volume. These standards were then run on a Jeol GC-Mate II mass spectrometer and analyzed to produce calibration curves. We present a manifold design that accurately generates gas standards of HFE-7100 and FC-72 and a procedure that allows the amount of each to be determined.

  5. Structure-based mutagenesis reveals the albumin-binding site of the neonatal Fc receptor

    PubMed Central

    Andersen, Jan Terje; Dalhus, Bjørn; Cameron, Jason; Daba, Muluneh Bekele; Plumridge, Andrew; Evans, Leslie; Brennan, Stephan O.; Gunnarsen, Kristin Støen; Bjørås, Magnar; Sleep, Darrell; Sandlie, Inger

    2012-01-01

    Albumin is the most abundant protein in blood where it has a pivotal role as a transporter of fatty acids and drugs. Like IgG, albumin has long serum half-life, protected from degradation by pH-dependent recycling mediated by interaction with the neonatal Fc receptor, FcRn. Although the FcRn interaction with IgG is well characterized at the atomic level, its interaction with albumin is not. Here we present structure-based modelling of the FcRn–albumin complex, supported by binding analysis of site-specific mutants, providing mechanistic evidence for the presence of pH-sensitive ionic networks at the interaction interface. These networks involve conserved histidines in both FcRn and albumin domain III. Histidines also contribute to intramolecular interactions that stabilize the otherwise flexible loops at both the interacting surfaces. Molecular details of the FcRn–albumin complex may guide the development of novel albumin variants with altered serum half-life as carriers of drugs. PMID:22215085

  6. Membrane proteins specified by herpes simplex viruses. V. Identification of an Fc-binding glycoprotein.

    PubMed Central

    Baucke, R B; Spear, P G

    1979-01-01

    A glycoprotein with affinity for the Fc region of immunoglobulin was isolated from extracts of cultured cells infected with herpes simplex virus type 1, and experiments were done to characterize its properties and to investigate whether it could account for the Fc-binding activity previously demonstrated on the surfaces of intact herpes simplex virus-infected cells. The technique of affinity chromatography was used to identify and isolate the Fc-binding glycoprotein and to demonstrate the specificity of its interaction with immunoglobulin G-Fc. Although three electrophoretically distinguishable Fc-binding polypeptides were identified by affinity chromatography, these three species appear to be different forms of the same translation product, based on comparisons of proteolytic digestion products and on the kinetics of appearance of each form after a brief pulse with radioactive amino acids. The results suggest that one polypeptide, designated pE, is processed to yield gE1, which is in turn processed to yield gE2. Both gE1 and gE2 are glycosylated membrane proteins and both can be labeled by the lactoperoxidase-catalyzed radioiodination of intact infected cells, indicating the presence of these proteins in surface membranes of the cells. Increases in the amounts of gE1 and gE2 at the cell surface were found to parallel the increase in Fc-binding activity of intact infected cells. Images PMID:229267

  7. In vivo and in vitro effects of dexamethasone on leukocyte migration in the rat adjuvant arthritis model

    SciTech Connect

    Thieme, T.R.; Mirkovich, A.; Maloney, P.; Goodwin, D.A.

    1982-12-01

    When polymorphonuclear leukocytes (PMNs) and mononuclear cells were isolated from the blood of dexamethasone-treated normal rats, in vitro mononuclear cell migration was inhibited and PMN migration was stimulated in comparison to controls. Inflammogen-induced PMNs showed inhibited cell migration due to dexamethasone treatment. Gamma camera imaging was then used to detect cells in vivo after labeling with /sup 111/In. When the dexamethasone-treated blood cells were injected into adjuvant arthritis diseased rats, mononuclear cells showed depressed migration into the inflamed paws, while PMNs showed stimulated migration into the inflamed paws in comparison to controls. When the recipient adjuvant arthritic animals were treated with dexamethasone, both normal mononuclear cell and normal PMN migration to the inflamed paws were inhibited.

  8. 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. PMID:26297757

  9. 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

  10. 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

  11. 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.

  12. Sequential Engagement of FcεRI on Mast Cells and Basophil Histamine H4 Receptor and FcεRI in Allergic Rhinitis

    PubMed Central

    Shiraishi, Yoshiki; Jia, Yi; Domenico, Joanne; Joetham, Anthony; Karasuyama, Hajime; Takeda, Katsuyuki; Gelfand, Erwin W.

    2012-01-01

    Histamine H4 receptor (H4R)-deficient mice (H4R−/−), H4R antagonist-treated WT mice, and WT mice depleted of basophils failed to develop early (EPR) or late phase (LPR) nasal responses following allergen sensitization and challenge. Basophil transfer from WT but not H4R−/− mice restored the EPR and LPR in H4R−/− mice. Following passive sensitization with OVA-specific IgE, FcεRI−/− recipients of WT basophils plus OVA and histamine developed an EPR and LPR. OVA-IgE passively sensitized FcεRI−/− recipients of H4R−/− basophils and OVA and histamine challenge failed to develop an EPR or LPR, and basophils were not detected in nasal tissue. In contrast, recipients of basophils from IL-13−/− and IL-4−/−/IL-13−/− mice developed an EPR but not LPR. These results demonstrate the development of allergic rhinitis proceeded in two distinct stages: histamine release from FcεRI-activated mast cells, followed by histamine-mediated recruitment of H4R-expressing basophils to the nasal cavity and activation through FcεRI. PMID:23241885

  13. Analysis of leukocyte populations in Canadian Holsteins classified as high or low immune responders for antibody- or cell-mediated immune response.

    PubMed

    Hine, Brad C; Cartwright, Shannon L; Mallard, Bonnie A

    2012-04-01

    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

  14. Altered Immunogenicity of Donor Lungs via Removal of Passenger Leukocytes Using Ex Vivo Lung Perfusion.

    PubMed

    Stone, J P; Critchley, W R; Major, T; Rajan, G; Risnes, I; Scott, H; Liao, Q; Wohlfart, B; Sjöberg, T; Yonan, N; Steen, S; Fildes, J E

    2016-01-01

    Passenger leukocyte transfer from the donor lung to the recipient is intrinsically involved in acute rejection. Direct presentation of alloantigen expressed on donor leukocytes is recognized by recipient T cells, promoting acute cellular rejection. We utilized ex vivo lung perfusion (EVLP) to study passenger leukocyte migration from donor lungs into the recipient and to evaluate the effects of donor leukocyte depletion prior to transplantation. For this purpose, female pigs received male left lungs either following 3 h of EVLP or retrieved using standard protocols. Recipients were monitored for 24 h and sequential samples were collected. EVLP-reduced donor leukocyte transfer into the recipient and migration to recipient lymph nodes was markedly reduced. Recipient T cell infiltration of the donor lung was significantly diminished via EVLP. Donor leukocyte removal during EVLP reduces direct allorecognition and T cell priming, diminishing recipient T cell infiltration, the hallmark of acute rejection. PMID:26366523

  15. In Vitro Glycoengineering of IgG1 and Its Effect on Fc Receptor Binding and ADCC Activity

    PubMed Central

    Thomann, Marco; Schlothauer, Tilman; Dashivets, Tetyana; Malik, Sebastian; Avenal, Cecile; Bulau, Patrick; Rüger, Petra; Reusch, Dietmar

    2015-01-01

    The importance and effect of Fc glycosylation of monoclonal antibodies with regard to biological activity is widely discussed and has been investigated in numerous studies. Fc glycosylation of monoclonal antibodies from current production systems is subject to batch-to-batch variability. If there are glycosylation changes between different batches, these changes are observed not only for one but multiple glycan species. Therefore, studying the effect of distinct Fc glycan species such as galactosylated and sialylated structures is challenging due to the lack of well-defined differences in glycan patterns of samples used. In this study, the influence of IgG1 Fc galactosylation and sialylation on its effector functions has been investigated using five different samples which were produced from one single drug substance batch by in vitro glycoengineering. This sample set comprises preparations with minimal and maximal galactosylation and different levels of sialylation of fully galactosylated Fc glycans. Among others, Roche developed the glycosyltransferase enzyme sialyltransferase which was used for the in vitro glycoengineering activities at medium scale. A variety of analytical assays, including Surface Plasmon Resonance and recently developed FcγR affinity chromatography, as well as an optimized cell-based ADCC assay were applied to investigate the effect of Fc galactosylation and sialylation on the in vitro FcγRI, IIa, and IIIa receptor binding and ADCC activity of IgG1. The results of our studies do not show an impact, neither positive nor negative, of sialic acid- containing Fc glycans of IgG1 on ADCC activity, FcγRI, and RIIIa receptors, but a slightly improved binding to FcγRIIa. Furthermore, we demonstrate a galactosylation-induced positive impact on the binding activity of the IgG1 to FcγRIIa and FcγRIIIa receptors and ADCC activity. PMID:26266936

  16. Autoantibodies to Type VII Collagen Mediate Fcγ-Dependent Neutrophil Activation and Induce Dermal-Epidermal Separation in Cryosections of Human Skin

    PubMed Central

    Sitaru, Cassian; Kromminga, Arno; Hashimoto, Takashi; Bröcker, Eva B.; Zillikens, Detlef

    2002-01-01

    Epidermolysis bullosa acquisita is an autoimmune subepidermal blistering disease associated with autoantibodies to type VII collagen, the major constituent of anchoring fibrils. Previous attempts to demonstrate the blister-inducing potential of autoantibodies to this protein have failed. To address this question, we used an in vitro model involving cryosections of human skin incubated with patients’ autoantibodies and leukocytes from healthy donors. We show that sera from 14 of 16 epidermolysis bullosa acquisita patients, in contrast to sera from healthy controls, induced dermal-epidermal separation in the cryosections. Recruitment and activation of neutrophils at the dermal-epidermal junction was necessary for split induction, whereas mononuclear cells were not required. Importantly, patients’ autoantibodies affinity-purified against a recombinant form of the noncollagenous 1 domain of type VII collagen retained their blister-inducing capacity in a dose-dependent manner, whereas patients’ IgG that was depleted of reactivity to type VII collagen lost this ability. Monoclonal antibody LH7.2 to the noncollagenous 1 domain of type VII collagen also induced subepidermal splits in the cryosections; F(ab′)2 fragments of autoantibodies to type VII collagen were not pathogenic. We demonstrate the capacity of autoantibodies to type VII collagen to trigger an Fcγ-dependent inflammation leading to split formation in cryosections of human skin. PMID:12107115

  17. 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

  18. Leukocyte Populations in Human Preterm and Term Breast Milk Identified by Multicolour Flow Cytometry

    PubMed Central

    Trend, Stephanie; de Jong, Emma; Lloyd, Megan L.; Kok, Chooi Heen; Richmond, Peter; Doherty, Dorota A.; Simmer, Karen; Kakulas, Foteini; Strunk, Tobias; Currie, Andrew

    2015-01-01

    Background Extremely preterm infants are highly susceptible to bacterial infections but breast milk provides some protection. It is unknown if leukocyte numbers and subsets in milk differ between term and preterm breast milk. This study serially characterised leukocyte populations in breast milk of mothers of preterm and term infants using multicolour flow cytometry methods for extended differential leukocyte counts in blood. Methods Sixty mothers of extremely preterm (<28 weeks gestational age), very preterm (28–31 wk), and moderately preterm (32–36 wk), as well as term (37–41 wk) infants were recruited. Colostrum (d2–5), transitional (d8–12) and mature milk (d26–30) samples were collected, cells isolated, and leukocyte subsets analysed using flow cytometry. Results The major CD45+ leukocyte populations circulating in blood were also detectable in breast milk but at different frequencies. Progression of lactation was associated with decreasing CD45+ leukocyte concentration, as well as increases in the relative frequencies of neutrophils and immature granulocytes, and decreases in the relative frequencies of eosinophils, myeloid and B cell precursors, and CD16- monocytes. No differences were observed between preterm and term breast milk in leukocyte concentration, though minor differences between preterm groups in some leukocyte frequencies were observed. Conclusions Flow cytometry is a useful tool to identify and quantify leukocyte subsets in breast milk. The stage of lactation is associated with major changes in milk leukocyte composition in this population. Fresh preterm breast milk is not deficient in leukocytes, but shorter gestation may be associated with minor differences in leukocyte subset frequencies in preterm compared to term breast milk. PMID:26288195

  19. An Incidental Detection of Popliteal Vein Aneurysm during Labeled Leukocyte Scintigraphy

    PubMed Central

    Hassan, H. Abu.; Nazri, M.; Azman, R. R.

    2012-01-01

    Technetium (99mTc) exametazime (hexamethylpropyleneamine oxime, HMPAO) labeled leukocyte scintigraphy is mainly used to exclude occult infection in our institution. On review of previously published article, no case of popliteal venous aneurysm was ever diagnosed and detected on labeled leukocyte scintigraphy. We present a rare case of popliteal venous aneurysm which was detected on labeled leukocyte scintigraphy and was further confirmed with single-photon emission computed tomography and computed tomography fusion. PMID:23372443

  20. Multiple Plasmodium falciparum Erythrocyte Membrane Protein 1 Variants per Genome Can Bind IgM via Its Fc Fragment Fcμ

    PubMed Central

    Jeppesen, Anine; Ditlev, Sisse Bolm; Soroka, Vladyslav; Stevenson, Liz; Turner, Louise; Dzikowski, Ron; Hviid, Lars

    2015-01-01

    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. PMID:26216422

  1. 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

  2. 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

  3. 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)

  4. 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. PMID:26018698

  5. 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

  6. 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

  7. 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. PMID:27210548

  8. 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.

  9. 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

  10. 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

  11. 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

  12. Adherence of Legionella pneumophila to guinea pig peritoneal macrophages, J774 mouse macrophages, and undifferentiated U937 human monocytes: role of Fc and complement receptors.

    PubMed Central

    Husmann, L K; Johnson, W

    1992-01-01

    Legionella pneumophila, the causative agent of Legionnaires' disease, is a facultative intracellular pathogen of alveolar macrophages. Although previous studies have demonstrated that specific antibody facilitates uptake of L. pneumophila by phagocytic cells, the role of complement has been unclear. Thus, we have examined the relative contributions of Fc gamma- and complement receptor-mediated adherence to guinea pig peritoneal macrophages, U937 human monocytic cells, and J774 mouse macrophage cells. Opsonization of L. pneumophila (Philadelphia 2) with polyclonal immunoglobulin G promoted maximum adherence to guinea pig macrophages. In contrast, incubation in the presence of 20% fresh nonimmune human serum from a single donor did not promote adherence. The results obtained with U937 and J774 cells paralleled those obtained with guinea pig macrophages. In the absence of specific antibody, opsonization with guinea pig complement did not enhance adherence of the Philadelphia 1, Philadelphia 2, or Knoxville strain. However, when complement was added to heat-inactivated, specific antiserum, a fourfold increase in the number of adherent organisms was observed. Blocking studies utilizing membrane receptor-specific monoclonal antibodies demonstrated that both Fc and complement receptors mediated adherence of organisms treated with complement in the presence of specific antibody. These results suggest that complement augments adherence of L. pneumophila only when acting in concert with specific antibody. PMID:1452353

  13. Immune-Stimulatory Effects of a Bacteria-Based Probiotic on Peripheral Leukocyte Subpopulations and Cytokine mRNA Expression Levels in Scouring Holstein Calves

    PubMed Central

    QADIS, Abdul Qadir; GOYA, Satoru; YATSU, Minoru; KIMURA, Atsushi; ICHIJO, Toshihiro; SATO, Shigeru

    2014-01-01

    ABSTRACT 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

  14. Staphylococci-induced Human Platelet Injury Mediated by Protein A and Immunoglobulin G Fc Fragment Receptor

    PubMed Central

    Hawiger, Jack; Steckley, Sylvia; Hammond, Dianne; Cheng, Charles; Timmons, Sheila; Glick, Alan D.; Des Prez, Roger M.

    1979-01-01

    Bloodstream infections with staphylococci are accompanied by thromboembolic complications. We have studied the mechanism of the interaction of staphylococci with human blood platelets. Staphylococci that possess protein A, a bacterial receptor for the Fc fragment of immunoglobulin G (IgG), caused aggregation of human platelets in whole plasma accompanied by release of [3H]serotonin. These reactions were time and concentration dependent, requiring two or more staphylococci per platelet to give maximal response within 5 min. The interaction between staphylococci and platelets required the presence of cell wall-bound protein A and of IgG with an intact Fc fragment. It did not require an intact complement system. Cell wall-bound protein A (solid phase) was capable of aggregating human platelets in whole plasma. In contrast, free, solubilized protein A (fluid phase) did not cause measurable aggregation, and release of [3H]serotonin was reduced. An excess of free, solubilized protein A blocked aggregation of human platelets induced by staphylococci in whole plasma. The role of the Fc fragment of IgG in the staphylococci-human platelet interaction was demonstrated by an experiment in which free, isolated Fc fragment blocked aggregation of platelets in whole plasma induced by staphylococci. Furthermore, binding of 125I-protein A to human platelets was demonstrated in the presence of complete IgG with intact Fc fragment but not in the presence of the F(ab)2 fragment. Binding of the protein A-IgG complex to the human platelet Fc receptor was paralleled by the release of [3H]serotonin. These results represent a novel example of the interaction of two phylogenetically different Fc receptors, one on prokaryotic staphylococci and the other on human platelets. Their common ligand, IgG, is amplified by one Fc receptor (protein A) to react with another Fc receptor present on human platelets, which results in membrane-mediated aggregation and release reaction occurring in whole

  15. 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

  16. 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.

  17. Suppression of Fcγ-receptor-mediated antibody effector function during persistent viral infection.

    PubMed

    Yamada, Douglas H; Elsaesser, Heidi; Lux, Anja; Timmerman, John M; Morrison, Sherie L; de la Torre, Juan Carlos; Nimmerjahn, Falk; Brooks, David G

    2015-02-17

    Understanding how viruses subvert host immunity and persist is essential for developing strategies to eliminate infection. T cell exhaustion during chronic viral infection is well described, but effects on antibody-mediated effector activity are unclear. Herein, we show that increased amounts of immune complexes generated in mice persistently infected with lymphocytic choriomeningitis virus (LCMV) suppressed multiple Fcγ-receptor (FcγR) functions. The high amounts of immune complexes suppressed antibody-mediated cell depletion, therapeutic antibody-killing of LCMV infected cells and human CD20-expressing tumors, as well as reduced immune complex-mediated cross-presentation to T cells. Suppression of FcγR activity was not due to inhibitory FcγRs or high concentrations of free antibody, and proper FcγR functions were restored when persistently infected mice specifically lacked immune complexes. Thus, we identify a mechanism of immunosuppression during viral persistence with implications for understanding effective antibody activity aimed at pathogen control. PMID:25680277

  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. Identification and characterization of a Fc receptor activity on the Toxoplasma gondii tachyzoite.

    PubMed

    Vercammen, M; el Bouhdidi, A; Ben Messaoud, A; de Meuter, F; Bazin, H; Dubremetz, J F; Carlier, Y

    1998-01-01

    The Immunoglobulin (Ig) binding capacity of Toxoplasma gondii tachyzoites was investigated using fluorescence flow-cytometry analysis. Polyclonal mouse, human and rat immunoglobulins without specific anti-Toxoplasma activity bound to parasites in a concentration-dependent manner, saturating them at circulating serum concentrations. The immunoglobulin class and subclass specificity of binding was investigated using irrelevant monoclonal antibodies. IgM, IgA and IgG reacted with the parasite membrane. The attachment of mouse IgM to the parasite surface was hampered by mouse IgG1, IgG2a, IgG2b and IgG3. The binding of mouse IgG was proportionally reduced with increasing concentrations of mouse monoclonal IgM. The binding of murine immunoglobulin was diminished when in presence of human IgG. Purified Fc- but not Fab portions of immunoglobulins, fixed to parasites. Using labelled calibrated beads, the Ig binding capacity of parasites was estimated to be 6900 +/- 500 sites per tachyzoite. The Kd of the T. gondii Fc Receptor (FcR) activity was determined at 1.4 +/- 0.1 microM (mean +/- SEM). Such FcR activity was reduced by phospholipase C, trypsin and pronase treatment of the parasites. These data show a low affinity FcR activity on T. gondii tachyzoites which recognizes Ig of different species and isotypes and is likely supported by a glycosyl-phosphatidylinositol (GPI)-anchored surface protein of the parasite. PMID:9491416

  20. Natural variation in Fc glycosylation of HIV-specific antibodies impacts antiviral activity

    PubMed Central

    Ackerman, Margaret E.; Crispin, Max; Yu, Xiaojie; Baruah, Kavitha; Boesch, Austin W.; Harvey, David J.; Dugast, Anne-Sophie; Heizen, Erin L.; Ercan, Altan; Choi, Ickwon; Streeck, Hendrik; Nigrovic, Peter A.; Bailey-Kellogg, Chris; Scanlan, Chris; Alter, Galit

    2013-01-01

    While the induction of a neutralizing antibody response against HIV remains a daunting goal, data from both natural infection and vaccine-induced immune responses suggest that it may be possible to induce antibodies with enhanced Fc effector activity and improved antiviral control via vaccination. However, the specific features of naturally induced HIV-specific antibodies that allow for the potent recruitment of antiviral activity and the means by which these functions are regulated are poorly defined. Because antibody effector functions are critically dependent on antibody Fc domain glycosylation, we aimed to define the natural glycoforms associated with robust Fc-mediated antiviral activity. We demonstrate that spontaneous control of HIV and improved antiviral activity are associated with a dramatic shift in the global antibody-glycosylation profile toward agalactosylated glycoforms. HIV-specific antibodies exhibited an even greater frequency of agalactosylated, afucosylated, and asialylated glycans. These glycoforms were associated with enhanced Fc-mediated reduction of viral replication and enhanced Fc receptor binding and were consistent with transcriptional profiling of glycosyltransferases in peripheral B cells. These data suggest that B cell programs tune antibody glycosylation actively in an antigen-specific manner, potentially contributing to antiviral control during HIV infection. PMID:23563315

  1. OPG-Fc but Not Zoledronic Acid Discontinuation Reverses Osteonecrosis of the Jaws (ONJ) in Mice.

    PubMed

    de Molon, Rafael Scaf; Shimamoto, Hiroaki; Bezouglaia, Olga; Pirih, Flavia Q; Dry, Sarah M; Kostenuik, Paul; Boyce, Rogely W; Dwyer, Denise; Aghaloo, Tara L; Tetradis, Sotirios

    2015-09-01

    Osteonecrosis of the jaws (ONJ) is a significant complication of antiresorptive medications, such as bisphosphonates and denosumab. Antiresorptive discontinuation to promote healing of ONJ lesions remains highly controversial and understudied. Here, we investigated whether antiresorptive discontinuation alters ONJ features in mice, employing the potent bisphosphonate zoledronic acid (ZA) or the receptor activator of NF-κB ligand (RANKL) inhibitor OPG-Fc, utilizing previously published ONJ animal models. Mice were treated with vehicle (veh), ZA, or OPG-Fc for 11 weeks to induce ONJ, and antiresorptives were discontinued for 6 or 10 weeks. Maxillae and mandibles were examined by μCT imaging and histologically. ONJ features in ZA and OPG-Fc groups included periosteal bone deposition, empty osteocyte lacunae, osteonecrotic areas, and bone exposure, each of which substantially resolved 10 weeks after discontinuing OPG-Fc but not ZA. Full recovery of tartrate-resistant acid phosphatase-positive (TRAP+) osteoclast numbers occurred after discontinuing OPG-Fc but not ZA. Our data provide the first experimental evidence demonstrating that discontinuation of a RANKL inhibitor, but not a bisphosphonate, reverses features of osteonecrosis in mice. It remains unclear whether antiresorptive discontinuation increases the risk of skeletal-related events in patients with bone metastases or fracture risk in osteoporosis patients, but these preclinical data may nonetheless help to inform discussions on the rationale for a "drug holiday" in managing the ONJ patient. PMID:25727550

  2. 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

  3. No association of primary Sjögren's syndrome with Fcγ receptor gene variants.

    PubMed

    Haldorsen, K; Appel, S; Le Hellard, S; Bruland, O; Brun, J G; Omdal, R; Kristjansdottir, G; Theander, E; Fernandes, C P D; Kvarnström, M; Eriksson, P; Rönnblom, L; Herlenius, M W; Nordmark, G; Jonsson, R; Bolstad, A I

    2013-06-01

    The genetic background of primary Sjögren's syndrome (pSS) is partly shared with systemic lupus erythematosus (SLE). Immunoglobulin G Fc receptors are important for clearance of immune complexes. Fcγ receptor variants and gene deletion have been found to confer SLE risk. In this study, four Fcγ receptor single-nucleotide polymorphisms (SNPs) and one copy number variation (CNV) were studied. Swedish and Norwegian pSS patients (N=527) and controls (N=528) were genotyped for the Fcγ receptor gene variant FCGR2A H131R (rs1801274) by the Illumina GoldenGate assay. FCGR3A F158V (rs396991) was analysed in 488 patients and 485 controls, FCGR3B rs447536 was analysed in 471 patients and 467 controls, and FCGR3B rs448740 was analysed in 478 cases and 455 controls, using TaqMan SNP genotyping assays. FCGR3B CNV was analysed in 124 patients and 139 controls using a TaqMan copy number assay. None of the SNPs showed any association with pSS. Also, no FCGR3B CNV association was detected. The lack of association of pSS with Fcγ receptor gene variants indicates that defective immune complex clearance may not be as important in pSS pathogenesis as in SLE, and may point to important differences between SLE and pSS. PMID:23552400

  4. Prolonged activity of factor IX as a monomeric Fc fusion protein.

    PubMed

    Peters, Robert T; Low, Susan C; Kamphaus, George D; Dumont, Jennifer A; Amari, John V; Lu, Qi; Zarbis-Papastoitsis, Greg; Reidy, Thomas J; Merricks, Elizabeth P; Nichols, Timothy C; Bitonti, Alan J

    2010-03-11

    Treatment of hemophilia B requires frequent infusions of factor IX (FIX) to prophylax against bleeding episodes. Hemophilia B management would benefit from a FIX protein with an extended half-life. A recombinant fusion protein (rFIXFc) containing a single FIX molecule attached to the Fc region of immunoglobulin G was administered intravenously and found to have an extended half-life, compared with recombinant FIX (rFIX) in normal mice, rats, monkeys, and FIX-deficient mice and dogs. Recombinant FIXFc protein concentration was determined in all species, and rFIXFc activity was measured in FIX-deficient animals. The half-life of rFIXFc was approximately 3- to 4-fold longer than that of rFIX in all species. In contrast, in mice in which the neonatal Fc receptor (FcRn) was deleted, the half-life of rFIXFc was similar to rFIX, confirming the increased circulatory time was due to protection of the rFIXFc via the Fc/FcRn interaction. Whole blood clotting time in FIX-deficient mice was corrected through 144 hours for rFIXFc, compared with 72 hours for rFIX; similar results were observed in FIX-deficient dogs. Taken together, these studies show the enhanced pharmacodynamic and pharmacokinetic properties of the rFIXFc fusion protein and provide the basis for evaluating rFIXFc in patients with hemophilia B. PMID:20056791

  5. Efficient Mucosal Delivery of Vaccine Using the FcRn-Mediated IgG Transfer Pathway

    PubMed Central

    Ye, Lilin; Zeng, Rongyu; Bai, Yu; Roopenian, Derry C.; Zhu, Xiaoping

    2011-01-01

    Vaccine strategies to prevent invasive mucosal pathogens are being sought because 80–90% of infectious diseases are initiated at mucosal surfaces. However, our ability to deliver an intact vaccine antigen across a mucosal barrier for induction of effective immunity is limited. The neonatal Fc receptor (FcRn) mediates the transport of IgG across polarized epithelial cells lining mucosal surfaces. By mimicking IgG transfer at mucosal surfaces, intranasal immunization with a model antigen, herpes simplex virus type-2 (HSV-2) glycoprotein gD fused with an IgG Fc fragment, in combination with the adjuvant CpG, resulted in complete protection of wild type, but not FcRn knockout, mice that were intravaginally challenged with virulent HSV-2 186. This immunization strategy induced efficient mucosal and systemic antibody, B and T cell immune responses, including memory immune responses, which remained stable at least 6 months post-vaccination and conferred protection for a majority of animals. These results demonstrate that the FcRn-IgG transcellular transport pathway may represent a novel mucosal vaccine delivery route for a subunit vaccine against abundant mucosal pathogens. PMID:21240266

  6. OPG-Fc but Not Zoledronic Acid Discontinuation Reverses Osteonecrosis of the Jaws (ONJ) in Mice

    PubMed Central

    de Molon, Rafael Scaf; Shimamoto, Hiroaki; Bezouglaia, Olga; Pirih, Flavia Q; Dry, Sarah M; Kostenuik, Paul; Boyce, Rogely W; Dwyer, Denise; Aghaloo, Tara L; Tetradis, Sotirios

    2016-01-01

    Osteonecrosis of the jaws (ONJ) is a significant complication of antiresorptive medications, such as bisphosphonates and denosumab. Antiresorptive discontinuation to promote healing of ONJ lesions remains highly controversial and understudied. Here, we investigated whether antiresorptive discontinuation alters ONJ features in mice, employing the potent bisphosphonate zoledronic acid (ZA) or the receptor activator of NF-κB ligand (RANKL) inhibitor OPG-Fc, utilizing previously published ONJ animal models. Mice were treated with vehicle (veh), ZA, or OPG-Fc for 11 weeks to induce ONJ, and antiresorptives were discontinued for 6 or 10 weeks. Maxillae and mandibles were examined by µCT imaging and histologically. ONJ features in ZA and OPG-Fc groups included periosteal bone deposition, empty osteocyte lacunae, osteonecrotic areas, and bone exposure, each of which substantially resolved 10 weeks after discontinuing OPG-Fc but not ZA. Full recovery of tartrate-resistant acid phosphatase-positive (TRAP+) osteoclast numbers occurred after discontinuing OPG-Fc but not ZA. Our data provide the first experimental evidence demonstrating that discontinuation of a RANKL inhibitor, but not a bisphosphonate, reverses features of osteonecrosis in mice. It remains unclear whether antiresorptive discontinuation increases the risk of skeletal-related events in patients with bone metastases or fracture risk in osteoporosis patients, but these preclinical data may nonetheless help to inform discussions on the rationale for a “drug holiday” in managing the ONJ patient. PMID:25727550

  7. The role of FcεRI expressed in dendritic cells and monocytes

    PubMed Central

    Greer, Alexandra M.

    2015-01-01

    Early studies regarding the function of FcεRI in dendritic cells (DCs) and monocytes have focused on its role in mediating inflammatory signaling and enhancing T cell immunity. It has been the case in part because FcεRI is the major receptor that mediates allergic inflammatory signaling in mast cells and basophils and because DCs and monocytes are antigen presenting cells capable of activating naϊve and/or effector T cells. These studies have led to the general belief that FcεRI-mediated DC signaling and antigen presentation promote development and activation of Th2 cells and contribute to allergic inflammatory diseases. However, this belief has long suffered from a lack of evidence. Recently, studies have emerged that provide evidence supporting an opposing role: that FcεRI on DCs instead promotes immune homeostasis and regulation. In this review, we will update the current status of our understanding of FcεRI biology and function, with a specific focus on DCs and monocytes. PMID:25715742

  8. Leukocyte Responsiveness to Exercise in Individuals Positive for Human Cytomegalovirus.

    PubMed

    Wilson, J N; Navalta, J W

    2016-05-01

    Human cytomegalovirus (HCMV) infects 50% of adults in the United States. HCMV can become a cause for concern in individuals who have a compromised immune system, which may occur after high-intensity exercise. The purpose of this preliminary study was to characterize the lymphocyte, monocyte, and neutrophil responses to exercise in HCMV+individuals. Participants were either positive (HCMV +) or negative (HCMV-) for HCMV. Participants visited the laboratory on 3 separate occasions: HCMV screening, 100% VO2max test, and 80% VO2max run. Mixed-model factorial ANOVA procedures with repeated measures on sampling condition were performed on absolute and relative circulating lymphocytes, monocytes, and neutrophils. Significant main effects for time for both absolute and relative values were seen for all leukocyte subsets regardless of virus status. Significant differences for absolute and relative values were seen between sampling conditions for all leukocyte subsets. We report for the first time that HCMV status does not affect circulating neutrophil responses to high-intensity exercise, though exercise-induced neutrocytosis is seen during the post-exercise and 60 min post-exercise sampling conditions, regardless of HCMV status. There is no HCMV effect on circulating monocyte responses to exercise, though exercise-induced monocytosis was seen during the post-exercise sampling condition regardless of HCMV status. PMID:26837931

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. Early and delayed indium 111 leukocyte imaging in Crohn's disease

    SciTech Connect

    Navab, F.; Boyd, C.M.; Diner, W.C.; Subramani, R.; Chan, C.

    1987-10-01

    Twenty-seven patients with Crohn's disease were studied for the presence and location of activity by both early (4 h) and delayed (18-24 h) indium 111 leukocyte imaging. The results were compared with other parameters of disease activity including Crohn's disease activity index, barium studies, and endoscopy. There was a correlation between early images and Crohn's disease activity index (r = 0.78) and between delayed images and index (r = 0.82). Based upon the corresponding Crohn's disease activity index, the sensitivity of early and delayed imaging was 81.0% and 95.2%, respectively. Specificity of early and delayed imaging was 75.0% and 87.0%, respectively. Presence of activity on the early and delayed imaging agreed with activity on barium studies and colonoscopy in approximately 80% of cases. Correlation of location of disease by leukocyte imaging and x-ray was observed in 58.9% of early scans and 55.0% of delayed scans. Correlation of the location of disease by imaging and endoscopy was observed in 71.4% of early and 75.0% of delayed studies. Because of the possibility of occurrence of false-negative results in early images, delayed imaging should always be included in evaluation of disease activity in patients with Crohn's disease who are suspected of having mild activity. Delayed imaging is not required if the early imaging study clearly shows activity.

  14. Modulation of Leukocyte Behavior by an Inflamed Extracellular Matrix

    PubMed Central

    Schor, Hagai; Vaday, Gayle G.

    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

  15. Interactions between CD44 and Hyaluronan in Leukocyte Trafficking

    PubMed Central

    McDonald, Braedon; Kubes, Paul

    2015-01-01

    Recruitment of leukocytes from the bloodstream to inflamed tissues requires a carefully regulated cascade of binding interactions between adhesion molecules on leukocytes and endothelial cells. Adhesive interactions between CD44 and hyaluronan (HA) have been implicated in the regulation of immune cell trafficking within various tissues. In this review, the biology of CD44–HA interactions in cell trafficking is summarized, with special attention to neutrophil recruitment within the liver microcirculation. We describe the molecular mechanisms that regulate adhesion between neutrophil CD44 and endothelial HA, including recent evidence implicating serum-derived hyaluronan-associated protein as an important co-factor in the binding of HA to CD44 under flow conditions. CD44–HA-mediated neutrophil recruitment has been shown to contribute to innate immune responses to invading microbes, as well as to the pathogenesis of many inflammatory diseases, including various liver pathologies. As a result, blockade of neutrophil recruitment by targeting CD44–HA interactions has proven beneficial as an anti-inflammatory treatment strategy in a number of animal models of inflammatory diseases. PMID:25741341

  16. Indium-/sup 111/ leukocyte imaging in appendicitis

    SciTech Connect

    Navarro, D.A.; Weber, P.M.; Kang, I.Y.; dos Remedios, L.V.; Jasko, I.A.; Sawicki, J.E.

    1987-04-01

    Indium-/sup 111/-labeled leukocyte scintigraphy was applied to the diagnosis of acute appendicitis. Thirty-two patients observed in the hospital for possible appendicitis were prospectively studied. Scanning was done 2 hr after radiopharmaceutical injection. Thirteen scans were positive for acute appendicitis, and all but one were confirmed at laparotomy. In addition, two cases of colitis and two cases of peritonitis were detected. Of 15 negative studies, 11 had a benign course. Four patients with negative studies had laparotomy; two were found to have appendicitis and two had a normal appendix. Of 14 proven cases of appendicitis, 12 scans were positive for appendicitis with one false-positive scan, providing a sensitivity of 86%. Specificity was 93%: all negative cases except one had negative scans. Overall accuracy was 91% (29 of 32), comparing favorably with the accepted false-positive laparotomy rate of 25%. Use of In-/sup 111/-labeled leukocyte scintigraphy serves to reduce the false-positive laparotomy rate and to shorten the clinical observation time in patients with acute appendicitis.

  17. 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

  18. Mononuclear Leukocyte Infiltrate in Extraplacental Membranes and Preterm Delivery

    PubMed Central

    Holzman, Claudia; Senagore, Patricia K.; Wang, Jianling

    2013-01-01

    Large numbers of polymorphonuclear leukocytes in the amnion and chorion define histological chorioamnionitis (HCA), a condition linked to spontaneous preterm delivery (PTD). Less is known about placental patterns of mononuclear leukocyte (MNL) density and PTD. In this prospective study (1998–2004), women were sampled from 52 clinics in 5 Michigan communities and enrolled at 16–27 weeks’ gestation. HCA and MNL distributions in delivered placentas were evaluated microscopically in a subcohort (290 preterm, 823 term). Midpregnancy biomarkers from maternal blood (i.e., C-reactive protein (CRP), corticotropin-releasing hormone, and cytokines) were compared among term and PTD subjects grouped by presence/absence of HCA and high MNL density. A density of more than 10 MNLs per high-power field in the chorion of the membrane roll, referred to as MNL-CMR, was associated with medically indicated PTD (odds ratio = 2.2, 95% confidence interval: 1.3, 3.6) and spontaneous PTD (odds ratio = 2.5, 95% confidence interval: 1.7, 3.7). Associations persisted after removal of women with HCA-positive placentas, abruption, hypertensive disorders, or obesity. HCA-associated PTD showed higher CRP and cytokine levels. MNL-CMR-associated PTD showed higher CRP and corticotropin-releasing hormone levels. These data suggest that an MNL infiltrate in the chorion of the membrane roll marks PTD pathways that are distinct from HCA and not entirely explained by pregnancy complications. PMID:23429723

  19. 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

  20. Ca2+-dependent Calmodulin Binding to FcRn Affects Immunoglobulin G Transport in the Transcytotic Pathway

    PubMed Central

    Dickinson, Bonny L.; Claypool, Steven M.; D'Angelo, June A.; Aiken, Martha L.; Venu, Nanda; Yen, Elizabeth H.; Wagner, Jessica S.; Borawski, Jason A.; Pierce, Amy T.; Hershberg, Robert; Blumberg, Richard S.

    2008-01-01

    The Fcγ receptor FcRn transports immunoglobulin G (IgG) so as to avoid lysosomal degradation and to carry it bidirectionally across epithelial barriers to affect mucosal immunity. Here, we identify a calmodulin-binding site within the FcRn cytoplasmic tail that affects FcRn trafficking. Calmodulin binding to the FcRn tail is direct, calcium-dependent, reversible, and specific to residues comprising a putative short amphipathic α-helix immediately adjacent to the membrane. FcRn mutants with single residue substitutions in this motif, or FcRn mutants lacking the cytoplasmic tail completely, exhibit a shorter half-life and attenuated transcytosis. Chemical inhibitors of calmodulin phenocopy the mutant FcRn defect in transcytosis. These results suggest a novel mechanism for regulation of IgG transport by calmodulin-dependent sorting of FcRn and its cargo away from a degradative pathway and into a bidirectional transcytotic route. PMID:18003977

  1. Improving the Anti-Toxin Abilities of the CMG2-Fc Fusion Protein with the Aid of Computational Design

    PubMed Central

    Peng, Hui; Chen, Hongxing; Chen, Huipeng; Hu, Xianwen; Yue, Junjie

    2014-01-01

    CMG2-Fc is a fusion protein composed of the extracellular domain of capillary morphogenesis protein 2 (CMG2) and the Fc region of human immunoglobulin G; CMG2-Fc neutralizes anthrax toxin and offers protection against Bacillus anthracis challenge. To enhance the efficacy of CMG2-Fc against anthrax toxin, we attempted to engineer a CMG2-Fc with an improved affinity for PA. Using the automatic design algorithm FoldX and visual inspection, we devised two CMG2-Fc variants that introduce mutations in the CMG2 binding interface and improve the computationally assessed binding affinity for PA. An experimental affinity assay revealed that the two variants showed increased binding affinity, and in vitro and in vivo toxin neutralization testing indicated that one of these mutants (CMG2-Fc(E117Q)) has superior activity against anthrax toxin and was suitable for further development as a therapeutic agent for anthrax infections. This study shows that the computational design of the PA binding interface of CMG2 to obtain CMG2-Fc variants with improving anti-toxin abilities is viable. Our results demonstrate that computational design can be further applied to generate other CMG2-Fc mutants with greatly improved therapeutic efficacy. PMID:25101992

  2. 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

  3. The anorexic effect of Ex4/Fc through GLP-1 receptor activation in high-fat diet fed mice.

    PubMed

    Liu, Rui; Ma, Duan; Li, Yiming; Hu, Renming; Peng, Yongde; Wang, Qinghua

    2014-08-01

    Exendin-4 (Ex4), a peptide initially found in the saliva of the Gila monster, can activate the signaling pathway of the incretin hormone glucagon-like peptide-1 (GLP-1) through the GLP-1 receptor (GLP-1R). We previously reported that a chimera protein consisting of Ex4 and mouse IgG heavy chain constant regions (Ex4/Fc) can exert biological effects of GLP-1, such as improving glycemic control and ameliorating manifestations in diabetic mice. The aim of this study was to determine whether Ex4/Fc is effective in modulating energy homeostasis in mice. Our results showed that in vivo expression of Ex4/Fc by intramuscular injection of the plasmid encoding Ex4/Fc followed by local electroporation effectively decreased food intake in the mice on high-fat diet (HFD) feeding. In addition, the reduced energy intake was associated with the decreased excrements from the Ex4/Fc-treated HFD mice but not the Fc control mice. Remarkably, the Ex4/Fctreated HFD mice displayed significantly lower triglyceride (TG) levels when compared with the control mice. Interestingly, while the leptin levels were not changed, the circulating ghrelin levels were higher in Ex4/Fc mice than those in the Fc control mice. These results suggested that Ex4/Fc can improve energy metabolism and lipid metabolism through GLP-1R in mice under excessive nutrition conditions. PMID:24951724

  4. TGEV infection up-regulates FcRn expression via activation of NF-κB signaling.

    PubMed

    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

  5. 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

  6. A RECOMBINANT IgG Fc THAT RECAPITULATES THE ANTI-INFLAMMATORY ACTIVITY OF IVIG

    PubMed Central

    Anthony, Robert M.; Nimmerjahn, Falk; Ashline, David J.; Reinhold, Vernon N.; Paulson, James C.; Ravetch, Jeffrey V.

    2008-01-01

    High doses of monomeric IgG purified from pooled human plasma confer anti-inflammatory activity for a wide variety of autoimmune diseases. The heterogeneity of IVIG, derived from its Fab specificity, IgG subclass distribution and variable glycosylation have confounded efforts to develop a recombinant substitute for this blood-derived product. Recent studies have demonstrated that this paradoxical anti-inflammatory activity of IgG is completely dependent on sialylation of the N-linked glycan of the IgG Fc fragment. Determining the precise glycan requirements for this anti-inflammatory activity allowed appropriate glycan engineering of an IgG1 Fc fragment, leading to the generation of a fully recombinant, sialylated IgG1 Fc with greatly enhanced potency. PMID:18420934

  7. 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

  8. Beneficial effects of secretory leukocyte protease inhibitor after spinal cord injury

    PubMed Central

    Ghasemlou, Nader; Bouhy, Delphine; Yang, Jingxuan; López-Vales, Rubèn; Haber, Michael; Thuraisingam, Thusanth; He, Guoan; Radzioch, Danuta; Ding, Aihao

    2010-01-01

    Secretory leukocyte protease inhibitor is a serine protease inhibitor produced by various cell types, including neutrophils and activated macrophages, and has anti-inflammatory properties. It has been shown to promote wound healing in the skin and other non-neural tissues, however, its role in central nervous system injury was not known. We now report a beneficial role for secretory leukocyte protease inhibitor after spinal cord injury. After spinal cord contusion injury in mice, secretory leukocyte protease inhibitor is expressed primarily by astrocytes and neutrophils but not macrophages. We show, using transgenic mice over-expressing secretory leukocyte protease inhibitor, that this molecule has an early protective effect after spinal cord contusion injury. Furthermore, wild-type mice treated for the first week after spinal cord contusion injury with recombinant secretory leukocyte protease inhibitor exhibit sustained improvement in locomotor control and reduced secondary tissue damage. Recombinant secretory leukocyte protease inhibitor injected intraperitoneally localizes to the nucleus of circulating leukocytes, is detected in the injured spinal cord, reduces activation of nuclear factor-κB and expression of tumour necrosis factor-α. Administration of recombinant secretory leukocyte protease inhibitor might therefore be useful for the treatment of acute spinal cord injury. PMID:20047904

  9. Leukocyte Cell Surface Proteinases: Regulation of Expression, Functions, and Mechanisms of Surface Localization

    PubMed Central

    Owen, Caroline A.

    2008-01-01

    A number of proteinases are expressed on the surface of leukocytes including members of the serine, metallo-, and cysteine proteinase superfamilies. Some proteinases are anchored to the plasma membrane of leukocytes by a transmembrane domain or a glycosyl phosphatidyl inositol (GPI) anchor. Other proteinases bind with high affinity to classical receptors, or with lower affinity to integrins, proteoglycans, or other leukocyte surface molecules. Leukocyte surface levels of proteinases are regulated by: 1) cytokines, chemokines, bacterial products, and growth factors which stimulate synthesis and/or release of proteinase by cells; 2) the availability of surface binding sites for proteinases; and/or 3) internalization or shedding of surface-bound proteinases. The binding of proteinases to leukocyte surfaces serves many functions including: 1) concentrating the activity of proteinases to the immediate pericellular environment; 2) facilitating pro-enzyme activation; 3) increasing proteinase stability and retention in the extracellular space; 4) regulating leukocyte function by proteinases signaling through cell surface binding sites or other surface proteins; and 5) protecting proteinases from inhibition by extracellular proteinase inhibitors. There is strong evidence that membrane-associated proteinases on leukocytes play critical roles in wound healing, inflammation, extracellular matrix remodeling, fibrinolysis, and coagulation. This review will outline the biology of membrane-associated proteinases expressed by leukocytes and their roles in physiologic and pathologic processes. PMID:18329945

  10. A simple rapid method for the removal of leukocytes from human blood.

    PubMed

    Palmer, E; Waldman, F; Dewitt, W

    1974-01-01

    Filtration of human blood cells through lamb's wool columns removed more than 96% of all leukocytes in a series of experiments, while the retention of erythrocytes by the column averaged 6.4%. This method should prove extremely useful for obtaining pure erythrocyte preparations for use in biochemical and physiological studies, and for removing leukocytes from blood prior to transfusion. PMID:4473869

  11. Seasonal variation of peripheral blood leukocyte telomere length in Costa Rica: a population based observational study

    PubMed Central

    Rehkopf, David H; Dow, William H; Rosero-Bixby, Luis; Lin, Jue; Epel, Elissa S; Blackburn, Elizabeth H

    2014-01-01

    Objectives Peripheral blood leukocyte telomere length is increasingly being used as a biomarker of aging, but its natural variation in human populations is not well understood. Several other biomarkers show seasonal variation, as do several determinants of leukocyte telomere length. We examined whether there was monthly variation in leukocyte telomere length in Costa Rica, a country with strong seasonal differences in precipitation and infection. Methods We examined a longitudinal population based cohort of 581 Costa Rican adults age 60 and above, from which blood samples were drawn between October 2006 and July 2008. Leukocyte telomere length was assayed from these samples using the quantitative PCR method. Multivariate regression models were used to examine correlations between month of blood draw and leukocyte telomere length. Results Telomere length from peripheral blood leukocytes varied by as much as 200 base pairs depending on month of blood draw, and this difference is not likely to be due to random variation. A moderate proportion of this association is statistically accounted for by month and region specific average rainfall. We found shorter telomere length associated with greater rainfall. Conclusions There are two possible explanations of our findings. First, there could be relatively rapid month-to-month changes in leukocyte telomere length. This conclusion would have implications for understanding the natural population dynamics of telomere length. Second, there could be seasonal differences in constituent cell populations. This conclusion would suggest that future studies of leukocyte telomere length use methods to account for the potential impact of constituent cell type. PMID:24615938

  12. Imaging of vascular development in early mouse decidua and its association with leukocytes and trophoblasts.

    PubMed

    Croy, B Anne; Chen, Zhilin; Hofmann, Alexander P; Lord, Edith M; Sedlacek, Abigail L; Gerber, Scott A

    2012-11-01

    In species with endometrial decidualization and hemochorial placentation (humans, mice, and others), leukocytes localize to early implant sites and contribute to decidual angiogenesis, spiral arterial remodeling, and trophoblast invasion. Relationships between leukocytes, trophoblasts, and the decidual vasculature are not fully defined. Early C57BL/6J implant sites were analyzed by flow cytometry to define leukocyte subsets and by whole-mount immunohistochemistry to visualize relationships between leukocytes, decidual vessels, and trophoblasts. Ptprc(+) (CD45(+)) cells increased in decidua between Gestational Day (GD) 5.5 and GD 9.5. Uterine natural killer (uNK) cells that showed dynamic expression of Cd (CD) 69, an activating receptor, and Klrg1 (KLRG1), an inhibitory receptor, localized mesometrially and were the dominant CD45(+) cells between GD 5.5 and GD 7.5. At GD 8.5, immature monocytes that occurred throughout decidua exceeded uNK cells numerically and many leukocytes acquired irregular shapes, and leukocyte-leukocyte conjugates became frequent. Vessels were morphologically heterogeneous and regionally unique. Migrating trophoblasts were first observed at GD 6.5 and, at GD 9.5, breached endothelium, entered vascular lumens, and appeared to occlude some vessels, as described for human spiral arteries. No leukocyte-trophoblast conjugates were detected. Whole-mount staining gave unparalleled decidual vascular detail and cell-specific positional information. Its application across murine models of pregnancy disturbances should significantly advance our understanding of the maternal-fetal interface. PMID:22954796

  13. Radiation-induced normal tissue injury: role of adhesion molecules in leukocyte-endothelial cell interactions.

    PubMed

    Quarmby, S; Kumar, P; Kumar, S

    1999-07-30

    The late onset of necrosis and fibrosis in normal tissues can be a serious consequence of radiotherapy in cancer patients. Because radiation-induced vascular injury precedes the tissue damage, vascular injury is regarded as crucial in the pathogenesis of tissue damage. An understanding of the processes responsible is essential to develop strategies for the amelioration of radiation-induced normal tissue damage. Leukocyte infiltration is commonly observed at sites of irradiation and is likely to lead to the acceleration and/or induction of parenchymal atrophy, fibrosis and necrosis in normal tissues following radiotherapy. The molecular mechanisms mediating leukocyte infiltration of tissues during inflammation have been studied extensively. It is now well established that cell adhesion molecules (CAMs) expressed on leukocytes and endothelial cells control the trafficking of leukocytes from the blood vessel lumen in these conditions. CAMs including E (endothelial), P (platelet) and L (leukocyte)-selectins, intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), beta1 and beta2 integrins and CD31 are involved in the cascade of events resulting in rolling, arrest and transmigration of leukocytes through the inflamed endothelium. Whether a similar sequence of molecular events induces leukocyte sequestration in irradiated normal tissues is not known. This review is focussed on the role of CAMs in radiation-induced leukocyte infiltration of normal tissues and the therapeutic implications of these findings. PMID:10399956

  14. Leukocyte accumulation promoting fibrin deposition is mediated in vivo by P-selectin on adherent platelets

    NASA Astrophysics Data System (ADS)

    Palabrica, Theresa; Lobb, Roy; Furie, Barbara C.; Aronovitz, Mark; Benjamin, Christopher; Hsu, Yen-Ming; Sajer, Susan A.; Furie, Bruce

    1992-10-01

    THE glycoprotein P-selectin is a cell adhesion molecule of stimulated platelets and endothelial cells, which mediates the interaction of these cells with neutrophils and monocytes1,2. It is a membrane component of cell storage granules3-6, and is a member of the selectin family which includes E-selectin and L-selectin7,8. P-selectin recognizes both lineage-specific carbohydrate ligands on monocytes and neutrophils, including the Lewis x antigen, sialic acid, and a protein component9-12. In inflammation and thrombosis, P-selectin may mediate the interaction of leukocytes with platelets bound in the region of tissue injury and with stimulated endothelium1,2. To evaluate the role of P-selectin in platelet-leukocyte adhesion in vivo, the accumulation of leukocytes within an experimental thrombus was explored in an arteriovenous shunt model in baboons13. A Dacron graft implanted within an arteriovenous shunt is thrombogenic, accumulating platelets and fibrin within its lumen. These bound platelets express P-selectin14. Here we show that antibody inhibition of leukocyte binding to P-selectin expressed on platelets immobilized on the graft blocks leukocyte accumulation and inhibits the deposition of fibrin within the thrombus. These results indicate that P-selectin is an important adhesion molecule on platelets, mediating platelet-leukocyte binding in vivo, that the presence of leukocytes in thrombi is mediated by P-selectin, and that these leukocytes promote fibrin deposition.

  15. Receptor cleavage and P-selectin-dependent reduction of leukocyte adhesion in the spontaneously hypertensive rat.

    PubMed

    Chen, Angela Y; Ha, Jessica N; Delano, Frank A; Schmid-Schönbein, Geert W

    2012-07-01

    The SHR, a genetic model for hypertension and the metabolic syndrome, has attenuated leukocyte adhesion to the postcapillary endothelium by an unknown mechanism. Based on recent evidence of elevated levels of MMPs in plasma and on microvascular endothelium of the SHR with cleavage of several receptor types, we hypothesize that the reduced leukocyte-endothelial interaction is a result of enhanced proteolytic cleavage of P-selectin on the postcapillary endothelium and PSGL-1 on leukocytes. The attenuated rolling interactions of SHR leukocytes with the endothelium were restored by chronic treatment with a broad-spectrum MMP inhibitor (CGS) for 24 weeks. The SHR MMP levels, in plasma and mesentery, as well as the systolic blood pressure, decreased significantly with treatment. In the SHR mesentery, labeling of P-selectin in the postcapillary venules by immunohistochemistry demonstrated, on average, a 31% lower extracellular P-selectin density compared with the normotensive WKY. A significantly lower extracellular PSGL-1 density on the membranes of SHR neutrophils compared with the WKY also supported our hypothesis. In vivo stimulation of the mesenteric postcapillary venules with histamine demonstrated that the SHR had an attenuated response, as measured by leukocyte rolling velocity on the endothelium. The reduced P-selectin and PSGL-1 density, on SHR postcapillary endothelium and on SHR leukocytes, respectively, was restored significantly by chronic MMP inhibition. The impaired ability of SHR leukocytes to reduce rolling velocity upon inflammatory stimulation led to fewer firmly adhered leukocytes to the endothelium as a contributor to immune suppression. PMID:22566571

  16. HARVESTING OF LEUKOCYTES FROM INTESTINAL LUMEN IN MURINE GIARDIASIS AND PRELIMINARY CHARACTERIZATION OF THESE CELLS

    EPA Science Inventory

    The aims of the study were to develop a method for harvesting leukocytes from the mouse small intestinal lumen and to identify leukocytes which enter the intestinal lumen of mice infected with Giardia muris. Giardia-infected and uninfected BALB/c mice were anesthetized, and the s...

  17. Fragmentation of gelatin-bound fibronectin (Fn) by inflammatory polymorphonuclear leukocytes (PMNL): A role for leukocyte elastase

    SciTech Connect

    Daudi, I.; Gudewicz, P.W.; Saba, T.M.; Cho, E.; Lewis, M. )

    1990-02-26

    Fragmentation of lung matrix Fn by proteases released from activated leukocytes sequestered in the lung has been implicated in lung vascular injury. The authors determined if Fn bound to a denatured collagen (gelatin) surface was susceptible to degradation by inflammatory PMNLs. Tissue culture wells coated with 1.5% denatured collagen (2 ml/well) prior to the addition of rat peritonal exudate cells, harvested 16 hours after i.p. sterile casein. Inflammatory PMNLs (1 {times} 10{sup 6}) stimulated with zymosan (1 mg) released 3 times more {sup 125}I-Fn into the culture media (DMEM) during a 4 hour incubation as compared to unstimulated PMNLs (2885{plus minus}95 cpm vs 1027{plus minus}82 cpm/100 ul). {sup 125}I-Fn released by stimulated PMNLs was markedly blocked by addition of a leukocyte elastase inhibitor (AAPVCK), moderately blocked by a trypsin inhibitor (TLCK), and not blocked by a thrombin inhibitor (Hirudin). Western blot analysis demonstrated fragmentation of released Fn. Thus, Fn complexed with denatured collagen is susceptible to proteolysis by stimulated inflammatory PMNLs. This may contribute to lung vascular injury with sepsis and intravascular coagulation which elicit sequestration of activated PMNLs in the lung.

  18. Expression of beta 2 integrins on blood leukocytes of cows with or without bovine leukocyte adhesion deficiency.

    PubMed

    Cox, E; Mast, J; MacHugh, N; Schwenger, B; Goddeeris, B M

    1997-09-19

    Peripheral blood leukocytes of 11 normal cows, 7 cows heterozygous and 2 heifers homozygous for bovine leukocyte adhesion deficiency (BLAD) were analysed by flow cytometry for the intensity of their beta 2 integrin expression (LFA-1(CD11a/CD18), CR3 (CD11b/CD18) and CR4 (CD11c/CD18)). BLAD-homozygotes revealed no or a very weak expression of the beta 2 integrins and had a 10-fold and 4- to 5-fold increase in absolute number of neutrophils and monocytes, respectively, whereas the absolute number of lymphocytes remained normal. The mean fluorescence intensity (MFI) of the beta 2 integrins (CD18) in heterozygous animals was 56 to 90% of this in the normal cows (MFI between 14 and 512). The difference in the expression level was most pronounced for LFA-1 on the small cluster of lymphocytes with the highest MFI for LFA-1. Repeated analysis and phorbol myristate acetate stimulation revealed that the LFA-1 expression on this high-expressing cell population of the peripheral blood allowed a ready identification of BLAD-heterozygotes by flow cytometry. PMID:9436269