Decrease of immunoglobulin G-Fc receptor-bearing T lymphocytes in Graves' disease.

Peripheral immunoglobulin G (IgG)-Fc receptor-bearing T lymphocytes (T gamma cells) in patients with autoimmune thyroid diseases and destruction-induced thyrotoxicosis were assayed by measuring erythrocyte antibody-rosette formation using a microplate technique. In untreated patients with Graves' disease, the percentage of T gamma lymphocytes (mean +/- SD, 8.9 +/- 3.9%; n = 15) was significantly lower (P less than 0.001) than that in normal controls (21.7 +/- 9.1%; n = 35). A similar decrease was found in thyrotoxic patients with Graves' disease under antithyroid drug therapy (12.1 +/- 5.6%; n = 11; P less than 0.01). Normal percentages were observed in euthyroid patients with Graves' disease under antithyroid drug therapy or in remission. In patients with Hashimoto's disease and destruction-induced thyrotoxicosis, the percentage of T gamma lymphocytes was similar to that in normal controls. The percentage of T gamma lymphocytes was significantly correlated inversely with the serum T4 level, the free T4 index, the T3 level, and the free T3 index in patients with autoimmune thyroid diseases, excluding those with Hashimoto's disease with destructive thyrotoxicosis. There were no correlations between T gamma lymphocytes and other variables, such as goiter size, the titer of antithyroid antibodies, or proptosis, in a group of untreated cases of autoimmune thyroid disease. The decreased proportion of T gamma lymphocytes in thyrotoxic patients with Graves' disease may be related to the perpetuation of thyrotoxicosis in patients with Graves' disease.