Circulating tissue factor and thrombosis

Tissue factor (TF) on circulating microparticles has recently received much attention as a factor in myocardial infarction. We have developed systems by which we have been able to investigate the thrombogenic potential of blo od-borne TF. Thrombi develop when native human blood is passed over either collagen-coated glass slides or over pig arterial media. These thrombi immu nostain for TF even when the substrate contains none. Moreover, we have dem onstrated that the deposited TF is active because the thrombi contain fibri n; fibrin deposition and thrombotic mass are both inhibited by the inclusio n of a potent TF-inhibitor in the perfusions. We have also shown that leuko cyte-derived particles attach to platelets in a reaction mediated by adhesi on proteins. (C) 2000 Lippincott Williams & Wilkins, Inc.