Evidence that thyroid-stimulating antibody is produced in the thyroid gland.

The hyperthyroidism in Graves' disease results from the action of thyroid-stimulating antibodies (TSAb). The thyroid gland in Graves' disease shows diffuse lymphocytic infiltration, and after removal of the gland antibody titres usually decline and patients go into remission. It is postulated that the lymphocytes in the thyroid may be an important site of TSAb production. 10 patients with Graves' disease and 8 patients with other thyroid disorders were studied. Blood was taken during operation, but before thyroid mobilisation, from the thyroid vein and simultaneously from a peripheral vein. In patients with Graves' disease the concentration of TSAb activity in the thyroid vein was much greater than that in the peripheral vein. TSAb was not detected in either peripheral vein or thyroid vein samples in the other patients. The increase in TSAb concentration in the thyroid vein indicates production of antibodies by lymphocytes within the thyroid and could explain why removal of the thyroid results in disappearance of TSAb from the circulation.