Platelet-derived microparticles in patients with arteriosclerosis obliterans: Enhancement of high shear-induced microparticle generation by cytokines

We evaluated the plasma concentrations of cytokines and platelet-derived mi croparticles in patients with arteriosclerosis obliterans and studied the e ffect of cytokines on platelet-derived microparticle generation under high shear stress. Interleukin-6 levels peaked at 48 hours after vascular surger y, while thrombopoietin started to increase at 24 to 48 hours postoperative ly and peaked on the seventh day. Platelet activation markers were increase d in the arteriosclerosis obliterans patients preoperatively. Levels of P-s electin and CD63 both increased further, peaking at 6 to 24 hours post oper atively. Platelet-derived microparticle levels were also increased preopera tively. At 6 hours post operatively, the plasma level of platelet-derived m icroparticles was significantly increased. Plasma platelet-derived micropar ticle level was lower at 12 hours but only returned to the preoperative val ue at 7 days after grafting. There was a difference in the platelet-derived microparticle level at 7 days between patients with or without antiplatele t therapy (cilostazol). The effect of cytokines on platelet activation unde r high shear stress was also studied. Interleukin-6 and thrombopoietin enha nced both P-selectin expression and platelet-derived microparticle generati on under high shear stress. These results suggest that platelet-derived mic roparticles are released by platelet activation after vascular grafting whe n certain cytokines increase under high shear stress and that antiplatelet therapy may reduce platelet-derived microparticle levels postoperatively. ( C) 2000 Elsevier Science Ltd. All rights reserved.