Effect of leucocyte products on platelet thrombus formation, coagulation and spontaneous thrombolysis, as measured from native human blood, in vitro.

Contribution of leucocytes to formation and lysis of arterial (platelet) thrombi was investigated. Secretory products of polymorphonuclear leucocytes (PMNs) during phagocytosis and cell lysates were prepared from eight volunteers. Platelet-rich thrombi were formed in flowing native human blood either by shear-stress or by collagen fibre, by haemostatometry. Tested in eight volunteers, PMN products significantly enhanced both thrombotic reactions and induced lysis of these thrombi. A specific inhibitor of leucocyte proteases (eglin c) inhibited platelet reaction to shear-stress and collagen and spontaneous thrombolysis. Our findings provide further evidence for the prothrombotic and potent thrombolytic effect of leucocytes associated with an arterial thrombus.