Methimazole has no dose-related effect on the intensity of the intrathyroidal autoimmune process in relapsing Graves' disease.

Declining thyroid autoantibodies during treatment and decreased lymphocytic infiltration after treatment of patients with Graves' disease suggest immunosuppressive actions of antithyroid drugs. However, the recent report of similar relapse rates after low and high dose carbimazole treatment of Graves' disease seems to contradict the immunosuppression thesis. We therefore determined the intrathyroidal methimazole concentrations with a high performance liquid chromatography method in 17 patients undergoing subtotal thyroid resection for relapsing Graves' disease. The intensity of the intrathyroidal infiltration by immunoglobulin G-producing plasma cells, activated T cells, and antigen presenting cells, and the total number of lymphocytes were identified immunohistologically with monoclonal antibodies for kappa- and lambda-immunoglobulin light chains, UCHL1, and the S100 antibody, respectively, followed by morphometry. The intrathyroidal methimazole concentration and the cumulative preoperative methimazole doses did not correlate with the intensity of the intrathyroidal infiltration by any of these immunocompetent cells. Comparison of groups with significantly different intrathyroidal methimazole concentrations (134 ng/g, n = 8 vs. 993 ng/g, n = 7) showed no significant differences for any of the intrathyroidal immunocompetent cells. These findings suggest that there is no dose-related effect of methimazole on the intensity of the intrathyroidal autoimmune process of patients with relapsing Graves' disease. They provide an explanation for why it does not seem justifiable to recommend higher methimazole doses than those required for the control of hyperthyroidism with the goal of immunosuppression.

The influence of iodine on the intensity of the intrathyroidal autoimmune process in Graves' disease.

Several lines of evidence support an etiological role of iodine for the initiation and perpetuation of autoimmune thyroid disease. However, varying relapse rates after increased iodine supplementation have been reported for Graves' disease. Furthermore the effects of iodine on the intensity of human autoimmune thyroiditis have previously only been investigated by indirect parameters and actions of iodine on thyroid function and a possible enhancement of the intrathyroidal autoimmune process in Graves' disease are difficult to separate in previous studies. Moreover lymphocytic thyroiditis in animal models has always been induced by considerably higher iodine doses as those used in in vivo studies. Therefore we investigated the effect of low and high iodine concentrations on the intensity of the intrathyroidal autoimmune process in Graves' disease. The intensity of intrathyroidal infiltration by lymphocytes, memory T cells, plasma cells and antigen presenting cells was determined by quantitative immunohistologic methods in 38 Graves' disease patients. 12 patients received additional preoperative iodine (group II) and 26 were treated with thiourelene antithyroid drugs only (group I). Urinary and intrathyroidal iodine concentrations were determined by a modified cer arsenite method in both groups. Application of high iodine doses in group II induced a significant increase of kappa and lambda positive plasma cells and interdigitating reticulum cells. This was not observed for activated T cells. There was no correlation between the extent of intrathyroidal infiltration by activated T cells, plasma cells and antigen presenting cells, and intrathyroidal or urinary iodine or intrathyroidal iodine concentrations in group I.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation of microsomal antibodies with the intensity of the intrathyroidal autoimmune process in Graves' disease.

Graves' disease is an organ-specific autoimmune disease, and intrathyroidal lymphocytes seem to be the major source of thyroid autoantibodies. Consequently, the intensity of the intrathyroidal lymphocytic infiltration is generally believed to reflect the activity of the autoimmune process. We, therefore, investigated the correlation of microsomal (enzyme immunoassay), thyroglobulin (RIA), and TSH receptor antibodies (RRA) with the degree of intrathyroidal infiltration by immunoglobulin G-producing plasma cells, activated T-cells, antigen-presenting cells, and the total number of lymphocytes. The immunocompetent cells were identified immunohistologically with monoclonal antibodies for immunoglobulins kappa and lambda, UCHL1, and the S100 antibody, respectively, in 26 thyroid glands of patients suffering from Graves' disease. The intensity of lymphocytic infiltration was determined by the point-counting method and by counting all lymphocytes and the labeled lymphocytes in 3 x 51 visual fields or 3 slides/thyroid gland. Microsomal antibodies correlated significantly (P = 0.001) with the total number of lymphocytes (r = 0.86), kappa (r = 0.71), lambda (r = 0.71), UCHL1 (r = 0.9), and S100 (r = 0.9) positive cells. These correlations were also significant for thyroglobulin antibodies. However, TSH receptor antibodies showed no significant correlations with any of the populations of immunocompetent cells. Patients with preoperatively undetectable TSH receptor or microsomal antibodies showed a broad variation of intrathyroidal infiltration by the immunocompetent cells investigated. Microsomal antibody titers, therefore, seem to reflect the intensity of the intrathyroidal autoimmune process in Graves' disease better than TSH receptor antibodies. However, the broad baseline variation in intrathyroidal infiltration observed with nondetectable thyroid antibodies will not always allow determination of the intensity of the intrathyroidal autoimmune process from microsomal or thyroglobulin antibody titers.