Inhibition by Fab and Fab'2 monoclonal anti-Ia antibody fragments of T-lymphocyte proliferative responses.
We investigated the capacity of anti-Ia monoclonal antibody Fab and Fab'2 fragments to inhibit keyhole limpet haemocyanin (KLH) or concanavalin A (Con A)-induced T-cell proliferations. Both types of fragments of anti-I-Ak and anti-I-E/Ck monoclonal antibodies inhibited these responses. On a protein concentration basis, the inhibitory effects of fragmented antibodies were less pronounced than those of undigested molecules. However, once the differences in antigen-binding capacity were compensated, antibody fragments were as efficient inhibitors as undigested molecules. These results suggest (i) that masking of Ia antigenic determinants is the essential mechanism of anti-Ia antibody-mediated inhibitory effect; (ii) that some KLH-specific proliferating T lymphocytes are I-E/Ck restricted; (iii) that the Ia antigen role is not limited to restriction of cell interactions since the Con A-induced proliferation, a non-H-2 restricted response, is inhibited by anti-Ia Fab fragments.
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology*; D003208:Concanavalin A / Q000494:pharmacology; D006433:Hemocyanins / Q000494:pharmacology; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007140:Immunoglobulin Fab Fragments / Q000276:immunology*; D007136:Immunoglobulins / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D013601:T-Lymphocytes / Q000276:immunology
D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II; D007140:Immunoglobulin Fab Fragments; D007136:Immunoglobulins; D003208:Concanavalin A; D006433:Hemocyanins