Characteristics of auto-antibodies to bovine TSH in the serum of two patients with Graves' disease.

In this report we describe the characteristics of auto-antibodies to bovine TSH (bTSH) detected in the serum of 2 females among 102 patients with Graves' disease. These patients had never been injected with bTSH. One patient had high LATS activity and high bTSH binding activity after isotope therapy. The other patient showed no detectable LATS activity. Interestingly, the antibody showed a specifically high binding activity for the labelled TSH preparation purified by receptor. The auto-antibody could be demonstrated by the double antibody method, polyethylene glycol method, and by gel-filtration. The antibody was polyclonal immunoglobulin G (IgG). Because the binding of [125I]bTSH with the patient's antibody was inhibited by pituitary extracts from mammalian species other than human, this antibody may cross-react with bovine, rat, dog, rabbit and whale TSH. Although the incidence of the antibody in Graves' disease is low and the pathological significance remains obscure, the existence of this antibody in the serum of patients may suggest that autoimmune mechanisms may involve not only the thyroid but also the pituitary in Graves' disease.