Comparative study on IgG and IgA antibodies against human thyroid and eye-muscle antigens in Graves' ophthalmopathy

Circulating IgG and IgA anti-thyroid and anti-eye muscle antibodies were investigated in 87 patients with Graves' disease (60 cases with ophthalmopathy). The ELISA method was used. Both IgG and IgA antibodies were demonstrated against human thyroid and eye-muscle membrane or cytosol antigens. Anti-eye-muscle antibodies of the IgA type were observed more frequently than those of the IgG type (25 cases vs. 18 were demonstrated with membrane antigens and 37 cases vs. 23 with cytosol antigens). The respective distributions for thyroid antigens the cytosol fraction were 55 cases vs. 13 and 18 cases vs. 36. A significant difference was observed in the anti-thyroid IgG levels and the anti-eye-muscle membrane or cytosol levels between the patients with Graves' disease and those in control group (P less than 0.001). The difference in the IgA antibody to thyroid and eye-muscle antigens was significant between the patients with and without ophthalmopathy (P less than 0.002). The strong correlation between the levels of IgA antibodies to thyroid and those to the eye-muscle cytosol fractions might be connected with the theory of the common aetiology of the thyroid and eye diseases in Graves' ophthalmopathy (P less than 0.001). Circulating IgA anti-human thyroid and eye-muscle antibodies seemed to have a diagnostic relevance in the development of ophthalmopathy in Graves' ophthalmopathy.