Failure of sera from patients with scleroderma to exhibit cytotoxicity towards human umbilical vein endothelial cells

Human umbilical vein endothelial cells grew equally well in sera from scleroderma patients and in sera from rheumatic controls. Using two independent methods of assessing cell growth, no evidence of a previously described endothelial cell cytotoxic factor could be found in heat inactivated sera from 23 scleroderma patients. The system used was sensitive in detecting growth inhibition due to five batches of foetal calf serum and low concentrations of homocysteine and 2-mercaptoethanol.