Specific stimulatory effects of Graves' IgG on the release of triiodothyronine from the patients' own thyroids.

The present study was undertaken to investigate the release of thyroid hormones from cultured thyroid slices of untreated patients with Graves' disease in response to autologous IgG and IgG from other untreated patients with Graves' disease. Thyroid tissue (8-10 mg) was obtained by needle biopsy from 11 untreated patients with Graves' disease, and each biopsy was divided into 5 slices. Slices were then cultured in Ham's F-12 synthetic media for 7 days with IgG (1.3 mg/ml) obtained from the same patients, IgG obtained from other untreated patients, normal IgG, or bovine TSH (1.3 mIU/ml). Media were changed every day, and the concentrations of triiodothyronine (T3) in the media were measured by radioimmunoassay (RIA), and the concentrations of thyroidal cAMP were measured by radioimmunoassay on the last day of culture after incubation with 10 mM theophylline at 37 degrees C for 30 min. When thyroid slices were incubated with autologous IgG, the release of T3 increased from the 3rd day, and the increase was 3- to 10-fold above controls on the 5th day, and the production of thyroidal cAMP significantly increased 2- to 3-fold. However, when slices were incubated with IgG obtained from other untreated patients, the concentration of T3 in media and the production of thyroidal cAMP did not differ from that in controls. TSH increased the release of T3 from thyroid slices 2.5- to 10-fold above controls on the 5th day and the production of cAMP 4- to 5-fold. These results strongly suggest that thyroid hormone releasing IgG in patients with Graves' disease are highly specific for autologous thyroids.(ABSTRACT TRUNCATED AT 250 WORDS)