Human muscle-derived, tissue specific, myocytotoxic T cell lines in dermatomyositis.

Mononuclear cells were isolated from the inflamed muscle tissue of a patient suffering from dermatomyositis (DM). These were expanded in long-term culture and maintained in the presence of IL-2 containing culture medium. Two cell lines were established, one of the helper/inducer (OKT4+) and the other of the suppressor/cytotoxic phenotype (OKT8+). The OKT4+ cell line exhibited a non HLA-restricted, tissue-specific, myocytotoxic effect on rat muscle cell culture. Its lymphoproliferative response to human muscle antigen was HLA-restricted. The OKT8+ cell line exhibited a non HLA-restricted, tissue-specific response to muscle antigens and no myocytotoxic activity in in vitro rat muscle cell culture. It is likely that clones of OKT4+ lymphocytes in patients suffering from DM are associated with the pathogenesis of the disease--they probably mediate the diffuse damage to skeletal muscle through their myocytotoxic activity.