Circulating immune complexes and thyroid-stimulating immunoglobulins before, during, and after antithyroid drug therapy in patients with Graves' disease.

Sera from patients with Graves' disease were assayed for thyroid-stimulating immunoglobulins (TSI) and circulating immune complexes (CIC) before, during, and after antithyroid drug treatment. 41 (72%) of 57 untreated patients had a positive TSI index and 17 (30%) had CIC. In untreated patients CIC were significantly more common in patients with a negative TSI index than in those with a positive one. It is suggested that because CIC prevent TSI from being detected the TSI index may be negative in Graves' disease. Early in the course of the treatment CIC developed in 85% of the patients; in all of these patients TSI disappeared. Later in the course of treatment when CIC could no longer be detected TSI did not reappear. These findings indicate that the development CIC could be the manifestation of the re-establishment of a natural tolerance to thyroid-stimulating hormone receptors in patients with Graves' disease.