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.
