[Platelet-derived microparticles].

Abstract

The presence of platelet fragments or platelet-derived microparticles (MP) in blood is of great interest, because it could be used as a marker for increased destruction or activation of platelets followed by their aggregation and vesiculation. In addition to early electronmicroscopic observations, a variety of methods to detect MP in plasma and serum have been developed, including immunoelectrophoresis, radioimmunoassay and the immunofluorescence test using flow cytometric analysis. In these techniques, monoclonal antibodies directed against platelet membrane specific antigens, such as glycoprotein (GP) IIb/IIIa or GP I b, have been used to distinguish platelet microparticles from other components. From basic and clinical investigations, MP has proved to be increased in some physiological and pathological conditions, including blood clotting, thrombin and collagen-induced activation of platelets, mechanical trauma of platelets, and immune-mediated platelet destruction. Furthermore, it has been shown that a significant part of platelet procoagulant activity resides on these small vesicles (MP), released from the platelet plasma membrane, on activation.