Lymphocytotoxic antibody in multiple sclerosis: activity against T cell subsets and correlation with disease activity.

Lymphocytotoxic activity has been found by previous investigators in multiple sclerosis (MS) sera. We confirmed the presence of this activity in MS sera using techniques designed to eliminate possible sources of erroneous conclusion not considered in previous studies. We further characterized this activity and found it to be non-dialysable and complement dependent, and, therefore, presumably to be an antibody. This lymphocytotoxic antibody (LCA) is found in those patients with active or progressive disease, and appears to be preferentially directed against the suppressor subset of T cells, as defined by monoclonal antibodies. The LCA may play a role in the pathogenesis of acute exacerbation of MS.