Intrathyroidal T cell activation and HLA-DR antigen expression on thyroid follicular cells in autoimmune thyroid diseases]

Thyroid specimens from 19 patients with Hashimoto's thyroiditis (HT), 11 with Graves' disease (GD), 4 with nontoxic goiter (NTG), 1 with subacute thyroiditis (SAT), 1 with thyroid adenoma and 4 from normal thyroids were investigated by alkaline phosphatase anti-alkaline phosphatase (APAAP) immunocytochemical technique. A group of monoclonal antibodies against the corresponding T cell activation antigens were used. The positive rates of all the four activation antigens in thyroid gland mononuclear cells (TG-MNC) were significantly higher in HT than in NTG (P less than 0.05-0.01). However, the differences between HT and GD were insignificant (P greater than 0.05) except for HLA-DR antigen. The activation antigen-positive (especially TLiSA 1+) TG-MNC were often seen intruding into thyroid lumens of HT. All the abnormal specimens expressed HLA-DR antigens on thyroid follicular cells (TFC) in different degrees (+/- to +3), and the degree in HT was significantly higher than that in GD (P less than 0.01) or NTG (P less than 0.05). The level of DR expression on TFC correlated significantly with the infiltrating degrees of T-activation-antigen-positive cells (P less than 0.01). This indicates that aberrant DR expression in vivo is closely related to the activation of intrathyroidal T cells.