Thyroid-infiltrating T lymphocyte subsets in Hashimoto's thyroiditis

Abstract

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.