In vitro study of cytotoxic factors against endothelium in childhood dermatomyositis

In a previous report we showed that leukocytes from a group of patients with childhood dermatomyositis (CDM) were not cytotoxic toward cultured normal human skeletal muscle cells. Blood products from 11 patients with CDM and 12 age- and sex-matched controls were tested for cytotoxicity toward human endothelium using a chromium 51 assay. Mixed lymphocytes, monocytes, and serum alone or in combination did not produce endothelial cell death. The combination of serum and leukocytes, however, did produce some cytotoxic effects in three of 11 patients with CDM. We conclude that those factors tested in vitro are not responsible for the endothelial cell death but together may produce cytotoxic changes in some patients.