Fc Gamma Receptors (fc + gamma_receptor)

Distribution by Scientific Domains

Selected Abstracts

Specific immunotherapy suppresses Th2 responses via modulating TIM1/TIM4 interaction on dendritic cells

ALLERGY, Issue 8 2010
C.-Q. Zhao
To cite this article: Zhao C-Q, Li T-L, He S-H, Chen X, An Y-F, Wu W-K, Zhou X-H, Li P, Yang P-C. Specific immunotherapy suppresses Th2 responses via modulating TIM1/TIM4 interaction on dendritic cells. Allergy 2010; 65: 986,995 Abstract Background:, Specific immunotherapy (SIT) is the only curable remedy for allergic disorders currently; however, the underlying mechanism is not fully understood yet. This study aimed to elucidate the mechanism of SIT on suppressing TIM4 (T cell immunoglobulin mucin domain molecule 4) expression in dendritic cells (DCs) and modulating the skewed T helper 2 (Th2) responses in patients with airway allergy. Methods:, Twenty patients with allergic rhinitis (AR) were treated with SIT for 3 months. Before and after SIT, the expression of TIM4 in peripheral DC and TIM1 in Th2 cells was examined. The role of Fc gamma receptor (Fc,R) I and II in modulating the expression of TIM4 in DCs was investigated. Results:, The interaction of TIM1/TIM4 played a critical role in sustaining the polarization status of Th2 cells in AR patients. Cross-linking Fc,RI by antigen/IgG complexes increased the production of TIM4 by dendritic cells via upregulating tumor necrosis factor-alpha in DCs. Exposure to microbial products promoted the expression of Fc,RI in DCs that further increased the expression of TIM4. Exposure to specific antigens alone upregulated the expression of Fc,RII in DCs, that suppressed the expression of TIM4. Conclusions:, We conclude that SIT suppresses the skewed Th2 responses via disrupting the interaction of TIM1/TIM4 in antigen-specific Th2 cells. [source]

Effect of immune serum and role of individual Fc, receptors on the intracellular distribution and survival of Salmonella enterica serovar Typhimurium in murine macrophages

IMMUNOLOGY, Issue 2 2006
Hazel Uppington
Summary Immune serum has a protective role against Salmonella infections in mice, domestic animals and humans. In this study, the effect of antibody on the interaction between murine macrophages and S. enterica serovar Typhimurium was examined. Detailed analysis at the single-cell level demonstrated that opsonization of the bacteria with immune serum enhanced bacterial uptake and altered bacterial distribution within individual phagocytic cells. Using gene-targeted mice deficient in individual Fc gamma receptors it was shown that immune serum enhanced bacterial internalization by macrophages via the high-affinity immunoglobulin G (IgG) receptor, Fc gamma receptor I. Exposure of murine macrophages to S. enterica serovar Typhimurium opsonized with immune serum resulted in increased production of superoxide, leading to enhanced antibacterial functions of the infected cells. However, opsonization of bacteria with immune serum did not increase either nitric oxide production in response to S. enterica serovar Typhimurium or fusion of phagosomes with lysosomes. [source]

Selective expression of inhibitory Fc, receptor by metastatic melanoma impairs tumor susceptibility to IgG-dependent cellular response

Lydie Cassard
Abstract During melanoma progression, patients develop anti-tumor immunity including the production of anti-tumor antibodies. Although the strategies developed by malignant cells to escape anti-tumor cellular immunity have been extensively investigated, little is known about tumor resistance to humoral immunity. The main effect of IgG antibodies is to activate the immune response by binding to host Fc gamma receptors (Fc,R) expressed by immune cells. We previously reported in a limited study that some human metastatic melanoma cells ectopically express the Fc,RIIB1, an inhibitory isoform of Fc,R. By analyzing a large panel of different types of human primary and metastatic solid tumors, we report herein that expression of Fc,RIIB is restricted to melanoma and is acquired during tumor progression. We show that Fc,RIIB expression prevents the lysis of human metastatic melanoma cells by NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) in vitro, independently of the intracytoplasmic region of Fc,RIIB. Using experimental mouse models, we demonstrate that expression of Fc,RIIB protects B16F0 melanoma tumors from the ADCC induced by monoclonal and polyclonal anti-tumor IgG in vivo. Thus, our results identify Fc,RIIB as a marker of human metastatic melanoma that impairs the tumor susceptibility to Fc,R-dependent innate effector responses. 2008 Wiley-Liss, Inc. [source]

Efficient expression and purification of human aglycosylated Fc, receptors in Escherichia coli,

Sang Taek Jung
Abstract Effector Fc gamma receptors (Fc,Rs) are expressed on the surface of a variety of cells of hematopoietic lineage and serve as a bridge between adaptive and innate immune responses. The interaction between immune complexes, formed by IgG class antibodies that are crosslinked with antigen, and Fc,Rs triggers signaling cascades that result in numerous cellular responses including the activation or donwregulation of cytotoxic responses, cytokine release, and antibody synthesis. Here, the extracellular domains of the human type I transmembrane Fc,Rs were expressed in Escherichia coli and their interactions to subclass IgGs (IgG1, IgG2, IgG3, and IgG4) antibodies were analyzed. Expression using fully synthetic E. coli codon optimized Fc,R genes and optimization of sequences for N-terminal translation initiation region through mRNA secondary structure prediction enabled us to achieve high yield of purified, bacterially expressed receptors, including Fc,RI and Fc,RIIIa which have not been successfully expressed in bacteria until now. The aglycosylated Fc,Rs showed similar IgG subclass binding selectivity compared to the respective glycosylated Fc,Rs expressed in mammalian cells. Biotechnol. Bioeng. 2010;107: 21,30. 2010 Wiley Periodicals, Inc. [source]