[Circulating HLA-DR (Ia) positive T cells and T cell activation by thyroglobulin, thyroid microsome and TSH-receptor in autoimmune thyroid diseases].

HLA-DR antigens are not expressed on normal circulating T lymphocytes, but recently it has become apparent that HLA-DR antigens are expressed on immunologically activated T lymphocytes, as well as monocytes, macrophages, and B lymphocytes. Namely, the HLA-DR antigens are considered to be one of the activated T cell antigens. It is apparent from the previous studies that increased numbers of HLA-DR positive T cells frequently appear in the circulation in systemic autoimmune diseases, such as RA and SLE. Furthermore, in such diseases, it is reported that the variations in circulating HLA-DR positive T cells are related to the activity of the diseases. In this communication, we examined the variations in HLA-DR positive T cells in the peripheral blood of the patients with autoimmune thyroid diseases. HLA-DR positive T cells were detected by cytotoxicity test using anti HLA-DR mouse monoclonal antibody (Leu-HLA-DR antibody) and rabbit complement. The results indicate that; 1) The percentage of HLA-DR positive T cells were increased in the patients with autoimmune thyroid diseases. 2) The changes of HLA-DR positive T cells accompanied with the stimulation by non-specific mitogens in vitro in autoimmune thyroid diseases did not differ from those in the normal controls. 3) The percentage of HLA-DR positive T cells increased by the stimulation of TSH-receptor and thyroid microsome in Graves' disease, on the other hand, it occurred by the stimulation of thyroglobulin and thyroid microsome in Hashimoto's thyroiditis. 4) The percentage of HLA-DR positive T cells were correlated with TRAb (TSH receptor Ab assayed by Smith's kit) in Graves' disease.(ABSTRACT TRUNCATED AT 250 WORDS)