Abstract

Twenty-eight randomly selected patients with multiple sclerosis (M.S.) were typed in the mixed-lymphocyte culture test for a specific lymphocyte determinant LD-7a by means of LD-7a homozygous stimulator cells. Nineteen (70%) of the patients were LD-7a positive, a frequency much higher than the 16% observed in healthy individuals. Thirteen of the patients carried HL-A7, and all of these were LD-7a positive, which is significantly different (p=0·004) from the frequency of about 56% of this determinant in twenty-five normal HL-A7 positive individuals. Of the remaining fifteen patients, six carried LD-7a, which is also a significantly higher frequency (p=0·009) than that observed in normal HL-A7 negatives (three in forty individuals). Family studies showed that the LD-7a character is inherited and not acquired. The progression of the disease was significantly (P<0·05) more rapid in LD-7a positive than in LD-7a negative patients, and thus LD-7a not only decreases the threshold for developing M.S. but also increases the rate of progression once the disease has developed.