title: Human antibody responses to bacterial antigens: studies of a model conventional antigen and a proposed model B cell superantigen.
abstract: We have investigated the human antibody repertoires that bind to two different classes of bacterial antigens. Immunization with the conventional antigen, type b capsular polysaccharide of Haemophilus influenzae Hib PS, uniformly induces IgA and IgG responses dominated by clones that use heavy chains structurally related to two subsets of VH3 genes, while in a minority of subjects antibodies from the VH1 or VH4 families are co-induced. In contrast, the "alternative binding site" of Staphylococcal Protein A (SPA) represents an unconventional determinant, because; (i) SPA is bound by a large proportion of non-immune IgM, IgA and IgG F(ab')2, (ii) SPA is bound only to Fab from the VH3 family, which can be encoded by at least four different germline genes, (iii) SPA binding is independent of VL usage, (iv) by flow cytometry SPA is bound by > 15% of tonsilar B cells, but not to T cells. (v) In vitro stimulation with an SPA containing mitogen induces the preferentially production of Ig bearing a VH3 marker. Taken together, these studies characterize a VH family restricted binding interaction that is distinct from the properties associated with conventional antigens such as Hib PS. Based on these data we propose that SPA represents a prototype for a B cell superantigen.
authors: Department of Medicine, University of California, San Diego, La Jolla 92093-0663.
authors: G J
authors: GJ
authors: Silverman
mesh_terms: D000595:Amino Acid Sequence; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D000916:Antibody Diversity / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D016667:Bacterial Capsules; D001428:Bacterial Vaccines / Q000276:immunology*; D018073:Haemophilus Vaccines; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000276:immunology; D008969:Molecular Sequence Data; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D013205:Staphylococcal Protein A / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001428:Bacterial Vaccines; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D011135:Polysaccharides, Bacterial; D013205:Staphylococcal Protein A