Thrombus formation without platelets under inflammatory condition: an in vitro study.

Platelet derived microvesicles, which are shed from platelets upon platelet activation, interact with monocytes in the blood. In this study the nature of this interaction was characterized in a model system with the monocytic cell line MM6 and isolated platelet derived microvesicles (PMV). The interaction of PMV with MM6 is separated in two consecutive steps, which are partially overlapped in time. In a first step there is an immediate conjugate formation with single MM6 and PMV, which was proved microscopically and by cytometry measurements. This process is dependent on CD62P, determined by an inhibition after pre-incubation with anti-CD62P. After a lag time of 4min this process is supplemented by an aggregate formation of single conjugates, which leads finally to one macroscopic visible aggregate. The Nature of this aggregate was characterized by immunohistochemistry and laser aggregatometry. An addition of GPRP blocks the formation of a fibrin network and also the aggregate formation, proving the neces...