The Influence of Iodine on the Intensity of the Intrathyroidal Autoimmune Process in Graves' Disease

Abstract

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)