A reconsideration of a thyroid-stimulating immunoglobulin as the cause of hyperthyroidism in Graves' disease.

Several assays for thyroid-stimulating immunoglobulins in the blood in patients with Graves' disease have been described recently; depending upon the method, different names have been used and distinct entities thus implied. Using an increase in cyclic AMP in the human thyroid slice after 2 h of incubation as an index of thyroid stimulation, we identified thyroid-stimulating activity in all of an unselected series of sera from 11 patients with hyperthyroidism of Graves' disease, but long-acting thyroid stimulator, by mouse bioassay, in only three. The theory is proposed that the thyroid-stimulating immunoglobulin is probably present in all such patients; it may be seen as a polyclonal antibody to a single human antigen that has a variable cross-reaction with a corresponding thyroid antigen in the mouse and in other species.