TSH receptor in Graves' disease(Receptor Diseases)

This report is referred to the recent knowledge of the TSH receptor antibody, which concerned with pathophisiological character of Graves' disease. 1) Method of measurement TSH receptor antibodies are usually classified as two classes according to method of measurement. One class, the TSH binding inhibitor antibody (TBIAb) or TSH binding inhibitor immunogroblins (TBII), blocks the binding of TSH to receptor and may impede subsequent TSH regulated events. The second class, the thyroid stimulating antibodies (TSAb), mimics the effect of TSH, causing hyperthyroidisum. 2) Relationship between TBII and TSAb In patients with untreated Graves' disease, there was no correlation between activity of TBII and that of TSAb. Furthermore, the mean value of TBII and TSAb activities in serum from two different patients with Graves' disease coincided with their activities in mixed serum from theirs respectively. These results support that TBII and TSAb show different activity respectively. 3) Clinical symptoms of Graves' disease and TSH receptor antibody a. Hyperthyroidism 1987, Nagataki et al. found that Graves' IgG increase secretion of T4 from thyroidal epithelial cells only when use own thyroid. This result supported the hypothesis that TSH receptor antibody have individual specificity about hyperthyroidisum. b. Graves' ophthalmopathy In studies, using the collagen biosynthesis assay involving measurement of [3H] proline incorporation into fibroblast, either IgG preparated from patients with Graves' opthalmopahthy or TSH receptor monoclonal antibody were shown to stimulate collagen biosynthesis, whether these antibodies are TSAb positive or not. But Graves' ophthalmopathy has been inexplicable only by this result. Recently, evidence was presented to suggest that antithyroglobulin antibodies are cross reacting with an orbital muscle. 4) Clinical application a. Decision of remission Clinical usefulness of TSH receptor antibodies for was evaluated as to the predicting the prognosis in patients with Graves' disease after cessation of antithyroid drug treatment, and compared with that of T3 suppression test. Among 43 patients who had been euthyroid on a maintenance dose of antithyroid drugs for at least 6 months, 28 patients had positive T3 suppressibility (group A) and 15 patients had not (group B). In group A, 1 patient relapsed within one year, and other remained in remission for more than lyear. Mean of TBII activity was significant higher in group B than in group A. But both activity were overlapping in each groups completely. This result mean that TSH receptor antibody is less useful than T3 suppressibility for decision of remission. b. Other clinical application Recent studies suggested that TSH receptor antibodies are available for the prediction of occurrence of neonatal thyrotoxicosis before delivery. Finally, TSH receptor antibodies may be available to analyze the cause of the Graves' disease