On the role of sensitised T-lymphocytes in the pathogenesis of multiple sclerosis.

Peripheral blood lymphocytes from 24 out of 26 patients with clinically well-defined multiple sclerosis in remission showed sensitisation to multiple sclerosis brain extracts as assayed by enhancement of the early erythrocyte rosette test. Such an increase in the number of early rosettes was not found when the lymphocytes of multiple sclerosis patients were exposed to extracts of control brains. In contrast the sensitised cells were found in the circulation in only two of 11 patients with multiple sclerosis in acute relapse. The percentage of circulating T-lymphocytes which formed early rosettes was lower in the group of patients suffering a relapse than in patients in remission. A longitudinal study of one patient who was tested before, during and after a relapse revealed the disappearance from the blood of the sensitised T-cells during the relapse and their subsequent reappearance after recovery. Of 36 patients with other neurological diseases, two responded solely to multiple sclerosis brain, two responded to both multiple sclerosis and control brain, and three responded only to control brain. No healthy controls showed sensitisation to any brain extract.