Increased frequency of lymphocytotoxic antibodies in patients with multiple sclerosis correlated with disease activity.

Cold-reactive lymphocytotoxic antibodies (LCA) were investigated in sera from patients with multiple sclerosis (MS) in relation to disease activity. When a serum with more than 20% cytotoxicity is considered positive for the presence of LCA, the positive frequency at remission was 21% (6/28), but at exacerbation it was 83% (10/12). All the sera from normal controls were negative. The average of cytotoxicity expressed as a % killing of target cells by sera at remission was 13%; on the other hand, at exacerbation it was 39%. These results showed that in multiple sclerosis the level of LCA was not persistently high, but increased correlating with the disease activity. From these findings and previous experiments of rescue of measles virus antigens, it was suggested that multiple sclerosis is likely a virus-induced autoimmune disease.