Circulating T-cell subsets in Graves' disease: differences between patients with active disease and in remission after 131I-therapy.

In the present investigation some surface markers in peripheral blood T lymphocytes of patients with active Graves' disease and subjects in remission after 131I-therapy have been studied. We confirmed low TG levels in untreated patients and normal values in treated subjects. Increased percentages of DR+, MLR4+ (activated T cells), and 5/9+ (inducer-helper) T cells were detected in patients with active disease, thus indicating the presence of activated T cells and suggesting increased levels of helper T cells. High percentages of MLR4+ and 5/9+, but normal levels of DR+ were found in 131I-treated subjects. The different distribution of DR and MLR4 positivities on 5/9+ and 5+9-T cells confirm the different meaning of these two markers of the activation state. The imbalance of T-cell subsets found in 131I-treated subjects and the normal values observed in patients with hyperthyroidism due to toxic adenoma indicate that hyperthyroidism per se is not sufficient to explain the T-cell alterations. The possible meaning of these findings is discussed with respect to previous hypotheses on the pathogenesis of Graves' disease.