title: All forms of human IgA antibodies bound to antigen interfere with complement (C3) fixation induced by IgG or by antigen alone.
abstract: Polyclonal human secretory IgA1 and IgA2 antibodies to a bacterial protein antigen Streptococcus mutans AgI/II, and polyclonal human serum IgA1 and IgA2 antibodies to staphylococcal alpha-toxin, were found to interfere with antigen-mediated C3b fixation. In fluid phase, immune complexes of antigen and IgA failed to fix C3b, whereas antigen-IgG complexes did fix C3b. Partial removal of glycan chains with Streptococcus mitis SK96 glycosidases diminished the capacity of IgA antibodies to interfere with antigen-mediated C3b fixation by the alternative complement pathway. The authors conclude that native serum or secretory IgA antibodies suppress C3b fixation, and that the glycan chains play a significant role in maintaining this property.
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham 35294.
authors.forename: E B
authors.initials: EB
authors.lastname: Nikolova
authors.forename: M
authors.initials: M
authors.lastname: Tomana
authors.forename: M W
authors.initials: MW
authors.lastname: Russell
mesh_terms: D000888:Antibodies, Anti-Idiotypic / Q000276:immunology* / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000276:immunology; D000912:Antibodies, Neoplasm / Q000276:immunology; D000936:Antigen-Antibody Complex / Q000276:immunology; D000941:Antigens / Q000276:immunology; D001666:Binding Sites, Antibody; D003179:Complement C3b / Q000378:metabolism*; D003168:Complement Fixation Tests; D003170:Complement Pathway, Alternative / Q000276:immunology; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000187:drug effects / Q000494:pharmacology; D007074:Immunoglobulin G / Q000494:pharmacology*; D009101:Multiple Myeloma / Q000276:immunology; D009844:Oligosaccharides / Q000494:pharmacology
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D000936:Antigen-Antibody Complex; D000941:Antigens; D007071:Immunoglobulin A, Secretory; D007074:Immunoglobulin G; D009844:Oligosaccharides; C049937:anti-IgA; D003179:Complement C3b