Circulating T cell subsets in euthyroid Graves' disease.

T cell subpopulations recognized by surfaces markers of different functional meaning have been evaluated in 12 female patients with euthyroid Graves' disease and in 2 patients with ophthalmopathy and Hashimoto's thyroiditis. We have used the following markers: i) receptors for Fc fragments of IgG; ii) antigens recognized by the monoclonal antibodies MLR4, 5/9, BT 2/9 (anti-DR). In the 12 patients with euthyroid Graves' disease a marked decrease of TG cells (which proved to exert suppressor function in several in vitro systems) was observed, as previously reported in hyperthyroid Graves' disease. The 2 Hashimoto's patients with eye changes had normal or high TG. 5/9+ T cells (which contain cells with helper activity in vitro), as well as MLR4+ and BT 2/9+ cells (activated T cells) were normal in the majority of patients, but elevated in the 2 Hashimoto's thyroiditis. The observed abnormality of TG cells in euthyroid Graves' disease might be consistent with the hypothesized autoimmune pathogenesis of endocrine ophthalmopathy.