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Cellular immune mechanisms in inflammatory myopathies

1997; Lippincott Williams & Wilkins; Volume: 9; Issue: 6 Linguagem: Inglês

10.1097/00002281-199711000-00007

1531-6963

Reinhard Hohlfeld, Andrew G. Engel, Norbert Goebels, L. Behrens,

Muscle Physiology and Disorders

The inflammatory myopathies include dermatomyositis, polymyositis, and inclusion body myositis. In dermatomyositis, muscle fiber injury is secondary to an antibody- or immune-complex- mediated immune response against a vascular-endothelial component. In polymyositis and inclusion body myositis, CD8+ T cells and macrophages invade and eventually destroy initially nonnecrotic muscle fibers. The autoaggressive T cells have the phenotype of activated (HLA-DR+) memory (CD45RO+) cells. T-cell receptor analyses indicate that the autoaggressive T cells are oligoclonal. In inflammatory lesions, muscle fibers express various cytoplasmic and surface molecules that are not detectable in normal fibers. These molecules, which include HLA class I antigens, heat-shock proteins, adhesion molecules, and Fas, are probably induced by locally secreted cytokines. The autoaggressive CD8+ T cells harbor granules containing perforin that aggregate near the contact zone with the target muscle fiber. This is consistent with a perforin- and secretion-dependent mechanism of muscle fiber injury. Many invaded muscle fibers also express the Fas “death receptor,” but signs of apoptosis are absent.