Lymphocyte transformation in the presence of myelin basic protein in multiple sclerosis and control subjects.

The transformation of lymphocytes in vitro in the presence of human myelin basic protein has been investigated in normal people, patients with multiple sclerosis (MS) and controls with other neurological diseases. There was little or no response at low concentrations (1--10 microgram/ml) but significant transformation at higher concentrations (100--1000 microgram/ml) in all three groups. There was no significant difference among the groups as a whole, but those MS patients who had had disease for more than 10 years did show greater responses than normal subjects (P less than 0.05). Increased responses could not be correlated with any other aspect of disease activity: in particular they were not increased in patients with acute relapses. The use of autologous serum instead of homologous AB Rhesus positive serum did not significantly alter lymphocyte responsiveness. The absence of any response in the presence of purified calf thymus histone suggests that the response to myelin basic protein indicates a low level of lymphocyte sensitization to this antigen even in normal subjects. The present evidence does not support a primary pathogenetic role for such a reaction in MS. The increased response in patients with a long duration of disease might merely be an effect of white matter damage or might represent an amplification of the normal immune response contributing to myelin breakdown and leading to the emergence of the progressive stage of the disease. The study of lymphocyte responsiveness over a wide range of concentrations of myelin basic protein is considered to resolve some of the controversy surrounding this subject in the literature.