Histological and histochemical studies on experimental allergic myositis and human polymyositis.

Some histological and histochemical findings on the allergic experimental myositis of guinea pig and human cases with neuromuscular diseases were reported. Innoculated animals showed hardly any clinical sings but histological changes of thigh muscle and diaphragma which were similar to those seen in human polymyositis. Diaphragma showed more remarkable changes than thigh muscle. In human polymyositis, the increase of endo-, epi-, and peri-mysial connective tissue, round cell infiltration into interstitial tissue, phagocytosis with regenerating fibre and necrosis of muscle fibre were dominant findings. Regarding histochemical findings, muscles from experimental animals showed reduction of phosphorylase activity, elevation of succinic dehydrogenase in early stage, slight reduction in late stage, and elevation of alkaline phosphatase in capillary elements. In human polymyositis, specimen of muscle showed mildely reduced phos· phorylase activity and little change of succinic dehydrogenase activity and in neuromuscular disease, succinic dehydrogenase activity was markedly reduced and phosphorylase activity was well retained. Finally, SGOT values in experimental animals were elevated on early stage then gradually reduced and SGPT values varied from case to case though the values throughout the course were higher than normal ones.