title: Monoclonal antibodies directed against human Ia antigens detect an evolutionary conserved epitope on guinea pig Ia antigens with unique functional properties.
abstract: Three murine monoclonal antihuman Ia antibodies were found to cross react with guinea pig Ia antigens. Sequential immunoprecipitation studies demonstrated that these antibodies recognized a subset of guinea pig Ia antigens. In competition binding studies, the antihuman Ia antibodies competed with each other, but not with a number of murine monoclonals raised directly to guinea pig Ia antigens. When the antihuman Ia monoclonals were tested for their ability to inhibit the proliferative response of primed guinea pig T cells to antigen-pulsed macrophages, they completely inhibited the response of strain 2 T cells to the complex antigen ovalbumin while having no effect on the response to the copolymer L-glutamic acid, L-lysine. In contrast, the monoclonals raised against guinea pig Ia had much less dramatic effects on the response of uncloned T cells to these antigens. These results suggest that the cross-reactive monoclonals may recognize an evolutionary conserved epitope on Ia that has a regulatory function in T-cell activation.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001667:Binding, Competitive; D003429:Cross Reactions; D000939:Epitopes; D006168:Guinea Pigs; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D007938:Leukemia / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice / Q000276:immunology; D013045:Species Specificity; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D000949:Histocompatibility Antigens Class II