Predisposing factors to thrombosis in systemic lupus erythematosus: possible relation to endothelial cell damage.

We studied 28 patients with SLE, five of whom had had thrombotic episodes. Platelet function and coagulation and fibrinolytic studies were performed to determine whether any of these factors may predispose to thrombosis in SLE. An inhibitor of blood coagulation was detected in 12 patients, and von Willebrand's syndrome was observed in two others. The most striking findings which could be correlated with thromboembolic phenomena were the increase in VII R:WF and the absence of plasminogen activator release after venous occlusion. Both proteins are synthesized by the endothelial cell, and the abnormalities observed are possibly related to damage of the vascular endothelium by immune complexes observed in SLE.