IgA autoantibodies against human eye muscle antigen detected by western blotting and immunohistochemical methods in Graves' disease.

The presence of IgA autoantibodies against human eye muscle was investigated in 40 patients with Graves' disease (33 had ophthalmopathy). IgA anti-eye muscle antibodies could be demonstrated in sera of patients using western blotting and immunohistochemical methods. For the detection of sera possessing autoantibodies against eye muscle antigen the indirect immunosorbent assay had been used. IgA anti-eye muscle antibodies could be demonstrated in 25 cases and IgG types in 16 cases out of 40 patients. These anti-muscle autoantibodies were associated with eye muscle rather than skeletal muscle, the number of positive cases with the latter being 5/40 for IgG and 2/40 for IgA. Immunoreactive bands of IgA autoantibodies against eye cytosol were found at 84, 64, 45, 40 and 25-23 kDa in 22, 2, 16, 2 and 18 cases, respectively. A difference was observed in the staining of IgG and IgA types of autoantibodies by immunohistochemical analysis of eye muscle tissue. The IgA anti-eye muscle antibodies reacted with muscle fibers and the IgG types showed staining on endomysium. No sera of Graves' disease patients gave staining on skeletal muscle tissue. The results supported the presence of IgA anti-human eye muscle antibodies in patients with Graves' ophthalmopathy, which might play a relevant role in the development of eye disease.