Thymosin administration in autoimmune disorders.

Five patients with autoimmune disorders were given thymosin, fraction 5, parenterally for periods ranging from 2 to 35 mth. Four patients had systemic lupus erythematosus and the 5th had rheumatoid arthritis and Sjögren's syndrome. Treatment with thymosin was based on the hypothesis of a T-suppressor defect in these autoimmune disorders. Circulating T lymphocytes increased and remained above pretreatment levels in all patients. Assays for cytotoxicity, using mouse thymocytes and patients' sera, were positive initially and declined during the course of the treatment. In all patients, serum cytotoxicity levels were reduced to zero. There has been clinical improvement in 3 patients, and in 1, the disease has become stable. The evaluation of the 5th patient has been inconclusive. No ill effects related to the administration of thymosin were observed.