Thyroid-infiltrating T lymphocyte subsets in Hashimoto's thyroiditis.

In Hashimoto's thyroiditis, the thyroid gland is infiltrated with immunocompetent lymphocytes. In this study we have used the fine needle aspiration technique to obtain thyroid-infiltrating lymphocytes from 11 HT patients for surface marker studies. The cells were characterized using conventional T and B cell markers as well as monoclonal antibodies (OKT) to different T cell subsets in a microscale immunofluorescence assay. We observed a relative decrease in intrathyroidal suppressor phenotype T (OKT 8+) cell numbers compared with peripheral blood (13% vs. 26%; P less than 0.01 by Wilcoxon signed rank test). This resulted in an increased helper to suppressor T (OKT 4+/OKT 8+) cell ratio (4.7 vs. 2.1; P less than 0.01). Within the gland, a significant local accumulation of B cells was also registered (27% vs. 12%; P less than 0.01). As to circulating lymphocyte subsets, no differences were found between 18 Hashimoto's thyroiditis patients and 26 normal subjects. Our results are compatible with a local synthesis of thyroid-directed antibodies and emphasize the importance of studying the local immunity in organ-specific autoimmune disease.