Murine monoclonal anti-myelin basic protein (MBP) antibodies inhibit proliferation and cytotoxicity of MBP-specific human T cell clones

Myelin basic protein (MBP)-specific T cell clones, isolated from two patients with multiple sclerosis, expressed the CD4⁺ phenotype and induced MBP-dependent cytolysis of autologous Epstein-Barr virus (EBV)-transformed B cells. The proliferation and cytolytic activity of the T cell clones were inhibited by four of a panel of five murine monoclonal anti-MBP antibodies in a dose-dependent manner. An isotype-matched antibody with a irrelevant specificity did not have such an effect. These MBP-specific monoclonal antibodies did not block phytohemagglutinin-induced T cell proliferation or allospecific cytotoxicity. These results suggest that some antibodies directed at the autoantigen MBP may play a regulatory role in T cell activation, rather than a pathogenic role, for which there is currently little supporting evidence.