Stimulation of human blood mononuclear cell procoagulant activity by cyclosporin A

Using a one-stage assay of plasma recalcification time, we have examined the procoagulant activity (PA) of human blood mononuclear cells following incubation for 20 h in the presence of cyclosporin A (CsA; 50-5,000 ng/ml). CsA alone caused a significant, dose-related increase in PA above basal values at 1,000 and 5,000 ng/ml. At these concentrations, it also enhanced the increases in PA produced by concanavalin A, phytohaemagglutinin and bacterial endotoxin. These effects of CsA were totally inhibited by actinomycin D or cycloheximide.