Suppressor T lymphocyte function in Graves' disease.

To explore suppressor T lymphocyte function in Graves' disease, studies were performed in one group of patients in the hyperthyroid state and in another group in the euthyroid state after treatment. Peripheral blood lymphocytes were cultured for 1-7 days. Pokeweed mitogen (PWM; 1.25 micrograms/ml) was added at the initiation of the cultures or after 24 h. The degree of lymphocyte activation was assessed by measurements of the cellular uptake of [3H]thymidine and expressed in counts per minute (CPM). The suppressor lymphocyte function was estimated by a quotient between the maximum CPM values from cultures with and without preincubation. For the hyperthyroid group (n = 15) the quotient was 1.00 +/- 0.07 (mean +/- SEM), for the euthyroid patient group (n = 21) 1.12 +/- 0.05 and for the healthy control group (n = 21) 1.37 +/- 0.08. There was a significant difference between the quotients for the control group and the hyperthyroid (P less than 0.01) as well as the euthyroid (P less than 0.05) patient group. The quotients for the two groups of patients did not differ significantly. In conclusion, the present study supports the view of a defect in suppressor T lymphocyte function in patients with Graves' disease in the hyperthyroid state and indicates that this defect can persist in the euthyroid state after treatment.