Cyclosporin-A and the OKT3 monoclonal antibody exert their respective inhibitory and mitogenic activity on T cells by interacting with the same receptors.
Cyclosporin-A strongly suppressed proliferation of T cells induced by the OKT3 monoclonal antibody when added at the beginning of the cultures but not when added 72 hr later. The inhibitory activity of Cyclosporin-A became apparent during the first 48 hr and was maintained throughout the culture period. Cyclosporin-A significantly inhibited binding of OKT3, but not OKT4 or OKT8, antibodies to T cells as determined by indirect immunofluorescence microscopy. In addition, Cyclosporin-A suppressed the killing of 51Cr labelled T cells mediated by OKT3 antibody plus complement, whereas Cyclosporin-A did not alter the lysis of T cells by OKT4 antibody plus complement treatment. These results strongly suggest that Cyclosporin-A and OKT3 antibody exert their respective suppressive and mitogenic activity on T cells by interacting with the same receptor.
D000911:Antibodies, Monoclonal / Q000276:immunology*; D001667:Binding, Competitive; D003524:Cyclosporins / Q000494:pharmacology*; D003601:Cytotoxicity Tests, Immunologic; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D008934:Mitogens / Q000494:pharmacology*; D011948:Receptors, Antigen, T-Cell; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D000911:Antibodies, Monoclonal; D003524:Cyclosporins; D007166:Immunosuppressive Agents; D008934:Mitogens; D011948:Receptors, Antigen, T-Cell