[The immunoreactivity studies of the idiopathic inflammatory myopathy over the past three years in our laboratory].

Biopsied skeletal muscles from patients with inflammatory myopathy (6 cases of polymyositis (PM), 2 cases of dermatomyositis (DM), 5 cases of collagen disease with polymyositis and a case of allergic granulomatous angitis) were examined by comparing immunostained infiltrated cells at perivascular, perimysial and the endomysial sites as well as examining the histochemical findings on serial frozen sections from cases examined by our laboratory over the past three years. CD68 was used for macrophage, L26 for B lymphocytes, CD4 and CD8 for T lymphocytes. Expression of HLA-ABC was examined for Class I antigen and HLA-DR for Class II antigen on the muscle fibers. Many macrophages and CD8-positive T lymphocytes had infiltrated the endomysium in PM. Many CD4-positive T lymphocytes and L26-positive B lymphocytes had infiltrated perivascular sites in DM. These results were almost the same as those in many other reports. HLA-ABC was positive on the muscle sarcolemma in all cases. However, the expression of HLA-DR was not identical in all cases. It is useful to determine the diagnosis and consider a pathogenesis of inflammatory muscle diseases to analyze the infiltrated cells and the site of infiltration even in case showing few of infiltrating cells and necrotic fibers.