The correlation between the results of tests for thyroid autoantibodies to cell surface and microsomal antigens and to thyroglobulin.

Autoantibodies reactive with human thyroid cell surface membrane and human thyroid microsomes were studied in sera of patients with autoimmune thyroid diseases and of controls. A strong correlation was found between the presence of antibodies reactive with the surface of human thyroid cells in tissue culture (detected by anti-IgG-immunofluorescence) and the presence of antibodies reactive with thyroid microsomes in cryostat sections of human thyroid tissue (detected by anti-IgG-FITC or by anti-C3c-FITC) or coated on the surface of turkey red cells (as detected by haemagglutination). This contrasts with the findings previously observed for islet cell antibodies in patients with Type 1 (insulin-dependent) diabetes. It suggests that in the case of thyroid cells, as opposed to islet cells, microsomal antigens are either also present in the thyroid cell surface membrane; or that microsomal and cell surface antigens (although separate and distinct) are very frequently associated with each other, with a strong tendency for autoantibodies to be formed against both antigens if they are formed at all.