Transfer of tissue factor from leukocytes to platelets is mediated by CD15and tissue factor

We describe thrombogenic tissue factor (TF) on leukocyte-derived microparti cles and their incorporation into spontaneous human thrombi. Polymorphonucl ear leukocytes and monocytes transfer TF+ particles to platelets, thereby m aking them capable of triggering and propagating thrombosis. This phenomeno n calls into question the original dogma that vessel wall injury and exposu re of TF within the vasculature to blood is sufficient for the occurrence o f arterial thrombosis. The transfer of TF+ leukocyte-derived particles is d ependent on the interaction of CD15 and TF with platelets. Both the inhibit ion of TF transfer to platelets by antagonizing the interaction CD15 with P -selectin and the direct inter action of TF itself suggest a novel therapeu tic approach to prevent thrombosis. (Blood. 2000;96:170-175) (C) 2000 by Th e American Society of Hematology.