Demonstration of circulating autoantibodies against the plasma membrane of isolated thyroid cells in Graves' disease.

Antibodies against the plasma membrane of isolated human and porcine thyroid cells were demonstrable by a linear fluorescence pattern in sera from 29 out of 37 patients with Graves' disease. In 3 cases the antibodies reacted only with human thyroid cells. In a group of patients with Hashimoto's thyroiditis, 6 of 8 sera reacted with human thyroid cells in a granular fluorescence pattern. With one exception, sera from patients with non-toxic goiter showed no binding of IgG to thyroid cells. Sera from healthy controls were negative in this test system. There was no correlation between the presence of antibodies against thyroid cells and antibodies against thyroglobulin. Antibodies against thyroid microsomal antigens were found in 80% of patients with circulating thyroid cell membrane antibodies; 5 sera with membrane antibodies were negative for microsomal antibodies. Twenty sera of patients with Graves' disease were tested by passive haemagglutination test against peak I and peak II of the human thyroid fractionation with Sephadex G100. Antibodies against peak I were found in 14 sera and against peak II in all 20 sera. The data indicate that the antibodies in sera from patients with Graves' disease are directed mainly against a species-unspecific antigen of the plasma membrane from thyroid cells with a probable molecular weight between 4-7 S and are unrelated to thyroglobulin.