EPITOPES ON THYROGLOBULIN - A STUDY OF PATIENTS WITH THYROID-DISEASE

Thyroglobulin antibodies (TgAbs) are typically found in autoimmune thy roid diseases and, more rarely, in nonautoimmune thyroid diseases and healthy subjects. To determine whether TgAbs associated with different conditions recognize different epitopes on the thyroglobulin molecule , we studied 28 patients with Hashimoto's thyroiditis, 30 with Graves' disease, 21 with thyroid carcinoma, 18 with nontoxic goiter, and 2 5 healthy subjects. All patients were selected for the presence of TgAbs ; 4/25 healthy subjects also had TpAbs. The sera were assayed for the their ability to inhibit the binding of monoclonal antibodies to thyro globulin in an ELISA assay. We found that: 1) TgAbs in Hashimoto's pat ients preferentially recognized three clusters of epitopes (II, III an d typically VI), with no difference between the goitrous and the atrop hic variants; 2) TgAbs in Graves' patients were directed toward cluste r II, with no difference between the presence or the absence of ophtha lmopathy; 3) TgAbs in thyroid carcinoma patients recognized the same c lusters as Hashimoto's patients; 4) TgAbs in nontoxic goiter patients and in the four healthy subjects showed no restriction in epitope reco gnition. We suggest that in individuals with no overt clinical or bioc hemical thyroid abnormalities but with TgAbs, the finding that these T gAbs recognize particular immunodominant clusters may be utilized to p redict full-blown thyroid disorders. Longitudinal studies are needed t o evaluate the possible clinical application of this methodology.