Possible pathogenic mechanisms in inflammatory myopathies

Possible mechanisms involved in the pathogenesis of idiopathic inflammatory myopathies, including immune and nonimmune processes that could affect muscle function, are discussed. The potential role of T cells and the role of the humoral;immune response in these disorders are summarized as are possible contributions from the muscle fibers, the nerves, and the blood vessels. Because the pathogeneses of the myositis syndromes remain undefined, immune effector processes, direct myotoxic effects of cytokines, metabolic abnormalities, and the effects of hypoxia should all be studied further to understand which are primary and which are secondary processes in these diverse diseases.