Relationship of eye muscle antibodies with HLA phenotypes and thyroid-stimulating immunoglobulins in endocrine orbitopathy.

The relationship between endocrine orbitopathy and Graves' hyperthyroidism is still not clarified. The purpose of this study was to elucidate the incidence of eye muscle antibodies and the relationship with HLA phenotypes and thyroid antibodies in 65 patients with endocrine orbitopathy classes 1-5. Both bovine and abdominal muscles were used as antigens in ELISA systems in which IgG and IgM antibodies were assayed. Before starting the immunosuppressant therapy, 46/65 patients (71%) showed a positive result for eye muscle antibodies. Those patients with an active disease had such antibodies more frequently. Where the ophthalmopathy was of recent onset IgM antibodies were found, whereas patients with chronic disease were mostly IgG-Ab positive. No association was found either with HLA phenotypes (B8, DR3) or with antibodies directed against thyroglobulin, thyroid microsomes, and the TSH receptor measured as thyroid-stimulating immunoglobulins. Furthermore, there was no correlation between ophthalmopathy class and optic muscle antibody-binding activity. There was no relation between the degree of exophthalmos and eye muscle, thyroid-stimulating, antithyroglobulin, or antithyroid microsomal antibodies. These results suggest that, although very closely related, endocrine orbitopathy and Graves' hyperthyroidism are separate, organ-specific autoimmune diseases.