Immunological characterization of mononuclear cells in thyroid gland and blood in Graves' disease, multinodular goiter and papillary carcinoma.

Mononuclear cell infiltrates in thyroid gland tissue sections from patients with drug-treated Graves' disease (n = 5), non-toxic nodular goiter (n = 12) and papillary carcinoma (n = 5) were characterized by immunological membrane receptors. T lymphocytes were identified using 2-aminoethylisothiouronium bromide hydrobromide (AET)-treated sheep erythrocytes (E) (E-AET). E sensitized with rabbit IgM antibodies (A) and human complement (C) (EAC) were used to detect receptors for C3b (B lymphocytes and monocytes) or C3d (B lymphocytes). E sensitized with rabbit IgG antibodies were used to detect receptors for the Fc portion of IgG (FcR; lymphocytes and monocytes). The results indicate that T and B lymphocytes infiltrate the thyroid gland in Graves' disease as well as in nodular goiter. T lymphocytes seemed to predominate in both disorders. In thyroid papillary carcinoma the number of B and T lymphocytes was negligible. However, EA absorbed strongly to sections from 3 of the 5 tumors studied, indicating the presence of FcR on tumor cells or infiltrating host cells. The percentage of active and total T lymphocytes in peripheral blood from the patients with drug-treated Graves' disease was markedly reduced (9 +/- 5 and 28 +/- 11%, controls 22 +/- 9 and 68 +/- 11%; p less than 0.01 and less than 0.001). In patients with nodular goiter the percentage of total T lymphocytes was slightly, but significantly decreased (p less than 0.05). We suggest that the marked decrease in blood T lymphocytes observed in Graves' disease might be caused by the drug therapy. In nodular goiter the predominance of T lymphocyte infiltration together with a slight decrease in blood T lymphocytes suggest that autoimmune mechanisms are involved in the pathogenesis.