title: Functional mapping of the Fc gamma RII binding site on human IgG1 by synthetic peptides.
abstract: Receptors specific for the Fc part of IgG (Fc gamma R) are expressed by several cell types and play diverse roles in immune responses. Impaired function of the activating and inhibitory Fc gamma R may result in autoimmunity. Thus, the modulation of IgG-Fc gamma R interaction can be a target for the development of treatments for some autoimmune and inflammatory diseases. This study addresses the localization and functional characterization of linear sequences in human IgG1 which bind to Fc gamma RII. Peptides with overlapping sequences derived from the CH2 domain of human IgG1 between P(234) and S(298) were synthesized and used in binding and functional experiments. Binding of the peptides to Fc gamma R was assayed in vitro and ex vivo, and peptides found to interact were functionally tested. The shortest effective peptide was T(256)-P(271), which bound to soluble recombinant Fc gamma RIIb with K(d)=6 x 10(6) M(-1). The biotinylated peptides R(255)-P(271) and T(256)-P(271) complexed by avidin exhibited functional activity; they induced Fc gamma RIIb-mediated inhibition of the BCR-triggered Ca(2+) response of human Burkitt lymphoma cells, and inflammatory cytokine production (TNF-alpha and IL-6) by the human monocyte cell line MonoMac. In conclusion, our results suggest that the selected peptides functionally represent the Fc gamma RII-binding part of IgG1.
authors.affiliation: Research Group of the Hungarian Academy of Science, Department of Immunology, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Dávid
authors.initials: D
authors.lastname: Medgyesi
authors.forename: Katalin
authors.initials: K
authors.lastname: Uray
authors.forename: Krisztina
authors.initials: K
authors.lastname: Sallai
authors.forename: Ferenc
authors.initials: F
authors.lastname: Hudecz
authors.forename: Gábor
authors.initials: G
authors.lastname: Koncz
authors.forename: Jakub
authors.initials: J
authors.lastname: Abramson
authors.forename: Israel
authors.initials: I
authors.lastname: Pecht
authors.forename: Gabriella
authors.initials: G
authors.lastname: Sármay
authors.forename: János
authors.initials: J
authors.lastname: Gergely
mesh_terms: D001665:Binding Sites / Q000276:immunology; D015153:Blotting, Western; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D018604:Epitope Mapping; D005434:Flow Cytometry; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry* / Q000276:immunology; D015850:Interleukin-6 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D009000:Monocytes / Q000276:immunology*; D010455:Peptides / Q000276:immunology* / Q000378:metabolism* / Q000494:pharmacology; D010766:Phosphorylation; D020836:Protein Structure, Quaternary; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D017452:Receptors, IgG / Q000737:chemistry* / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects / Q000378:metabolism
chemical_list: D007074:Immunoglobulin G; D015850:Interleukin-6; D010455:Peptides; D011947:Receptors, Antigen, B-Cell; D017452:Receptors, IgG; D014409:Tumor Necrosis Factor-alpha; D020928:Mitogen-Activated Protein Kinases