RESUMEN
Using a mouse model, we have investigated the in vivo effect of cyclosporin on macrophage procoagulant activity and on plasma levels of plasminogen activator inhibitor. Procoagulant activity of peritoneal macrophages was studied after treatment of mice with different regimens of cyclosporin (10 to 100 mg/kg body weight) for seven days. No significant difference was found between treated and control animals in both basal procoagulant activity and procoagulant activity generated during short-term culture in the absence or in the presence of endotoxin. These findings are in striking contrast with in vitro experiments showing that cyclosporin induced a significant increase in procoagulant activity when added to peritoneal macrophages from normal animals before challenge with endotoxin (p less than 0.01). Plasma levels of plasminogen activator inhibitor in cyclosporin-treated mice were not different from those of controls. It is suggested that factors other than monocyte-macrophage procoagulant activity or plasminogen activator inhibitor may be important for the postulated 'prothrombotic' action of cyclosporin.