Inhibition of rat autoimmune T cell activation by monoclonal antibodies

The essential requirement for adoptive transfer of autoimmune diseases such as experimental allergic encephalomyelitis (EAE) by T lymphoblasts from established T cell lines, is a prior activation of these cells by autoantigen or mitogen. We have investigated the possibility of modulating this activation process by using monoclonal antibodies directed against rat leukocyte differentiation antigens. We report here that antigen-driven activation of autoimmune, encephalitogenic T cells from established myelin basic protein (MBP)-specific rat T cell lines can be inhibited by some, but not all, antibodies against RT1.B Class II restriction elements. In addition, monoclonal antibodies with specificity for rat leukocyte common antigen (OX-1) and T cell differentiation antigens W3/13 and W3/25 are inhibitory, while monoclonal antibody OX-8 with specificity for T cytotoxic/suppressor cells has no effect. We also observed that concanavalin A-induced activation of the T cells is more resistant to the inhibitory effect of monoclonal antibodies, and can be blocked effectively only by antibody OX-1. This demonstration that autoimmune T cell function can be inhibited by monoclonal antibodies points the way in suggesting cellular targets for immunotherapeutic purposes.