THYROTROPIN RECEPTOR ANTISERA FOR THE DETECTION OF IMMUNOREACTIVE PROTEIN SPECIES IN RETROOCULAR FIBROBLASTS OBTAINED FROM PATIENTS WITH GRAVES OPHTHALMOPATHY

Autoimmunity against the TSH receptor (hTSH-R) is known to be the prox imate cause of thyroidal activation in Graves' disease, but has not be en definitively linked to extrathyroidal manifestations of this disord er, such as ophthalmopathy and pretibial myxedema. In an effort to inc rease our knowledge concerning mechanisms responsible for Graves' opht halmopathy, we used antiserum directed against a highly immunogenic po rtion of the hTSH-R (amino acids 352-367; P1) to assess the presence o f this receptor or immunologically related protein in cultured human r etroocular fibroblasts obtained from patients with Graves' ophthalmopa thy. Immunoenzymatic and immunofluorescent studies revealed specific s taining of both cytoplasmic and cell membrane-associated protein in di screte vesicles. To further evaluate the immunoreactive species presen t in these cells, immunoblotting experiments were performed using hTSH -R-specific antisera (anti-P1) and sera obtained from patients with Gr aves' disease. Several protein bands were identified using both anti-P 1 and Graves' disease patient sera, including species at mol wt of 95, 71, and 18 kilodaltons, the possible significance of which is discuss ed. The results support the hypothesis that immunity against the hTSH- R or related proteins contributes to the ophthalmopathy of Graves' dis ease.