Circulating activated T cell subsets in autoimmune thyroid diseases: differences between untreated and treated patients.

To investigate the relationships between lymphocyte subsets and thyroid function, peripheral blood lymphocytes were analysed with cell surface antigens of activated (HLA-DR+) T, helper T (CD4+ 2H4-, CD4+ 4B4+) and suppressor-inducer T (CD4+ 2H4+, CD4+ 4B4-) cells subsets in 56 patients with Graves' disease, 16 patients with Hashimoto's thyroiditis, 7 patients with typical subacute thyroiditis and 2 patients with the thyrotoxic phase of autoimmune thyroiditis. Both patients with Graves' disease and Hashimoto's thyroiditis had increased percentages of HLA-DR+ T (Ia+ CD3+) cells as well as HLA-DR+ helper-inducer T (Ia+ CD4+) cells, which seemed to be independent of treatments. The percentage of HLA-DR+ suppressor-cytotoxic T (Ia+ CD8+) cells was increased in euthyroid or hypothyroid patients with Graves' disease following treatment, but was normal in hyperthyroid patients. The percentages of Ia+ CD4+ cells and Ia+ CD8+ were also increased in patients with thyroiditis, whereas these abnormal values normalized in the remission phase. These findings suggest that an increase in Ia+ CD4+ cells characteristically occurs during immune system activation in patients with hyperthyroid Graves' disease, Hashimoto's thyroiditis and the thyrotoxic phase of subacute thyroiditis, whereas the activated CD8+ cells in Graves' disease are induced by antithyroidal therapy.