Absence of cell-mediated cytotoxicity to muscle cultures in polymyositis.

Blood mononuclear cells from 10 patients with polymyositis and 22 controls were incubated with fetal-rat muscle cultures. Polymyositis cells produced no significant cytotoxic effects in cultures as determined by visual inspection and measurement of the release from cultures of creatine phosphokinase and radioactive chromium. These negative results contrast with previous reports and raise the question of whether blood mononuclear cells from polymyositis patients are cytotoxic for muscle cultures.