[Immunoglobulin deposition in skeletal muscle in polymyositis and dermatomyositis]

An immunohistochemical study was conducted using the biotin avidin technique in 22 muscle specimens from PM/DM patients and 19 control subjects. Deposition of IgG, IgM or C3 in the wall of capillaries and small vessels was demonstrated in 72.7% of PM/DM patients and in 31.6% of those with other neuromuscular disorders. This finding supports the contention that immunoglobulins and complement-mediated immunoreaction may play an important role in PM/DM pathogenesis.