ANTIBODIES REACTIVE WITH AN INTRACELLULAR EPITOPE OF A RECOMBINANT 64-KDA THYROID AND EYE MUSCLE PROTEIN IN PATIENTS WITH THYROID AUTOIMMUNITY AND OPHTHALMOPATHY

We have developed an enzyme-linked immunosorbent assay (ELISA) for the measurement of antibodies reactive with a 98 amino acid fragment, cal led D1, of a recombinant thyroid and eye muscle membrane protein corre sponding to a MW of 64 kDa (called D) in the serum of patients with th yroid autoimmunity with and without ophthalmopathy. Antibodies against the D1 fragment expressed as a fusion protein with beta galactosidase , were detected in 29% of patients with thyroid-associated ophthalmopa thy (TAO) of <1 yr duration, in 33% of those with disease of >3 yr dur ation, in 40% of patients with Graves' hyperthyroidism (GH) without ev ident eye disease, in 31% of patients with lid lag and retraction but no other signs of progressive ophthalmopathy, in 25% of patients with euthyroid Graves' disease and in 43% of patients with untreated Hashim oto's thyroiditis (HT), but in none of 14 patients with other (non-imm unological) thyroid disorders. Although tests were positive in 6 out o f the 15 patients with ophthalmopathy and no overt thyroid autoimmunit y overall there was no close association of the antibodies with clinic al features of the eye disease or its course. In those sera in which W estern blotting for antibodies reactive with a 64 kDa eye muscle membr ane protein and ELISA were both carried out there was no close correla tion between the two tests. In order to better understand the signific ance of antibodies reactive with 64 kDa eye muscle and thyroid membran e autoantigens and their possible relationship to ophthalmopathy it wi ll be necessary to perform prospective studies of patients with untrea ted Graves' hyperthyroidism beginning before the onset of eye signs, u sing antibody assays incorporating full length recombinant proteins.