Changes of tissue factor-dependent coagulant activity mediated by adhesionbetween polymorphonuclear leukocytes and endothelial cells

The purpose of this study was to examine whether polymorphonuclear leukocyt es (PMNs) facilitate a tissue factor, a physiologic initiator of coagulatio n in endothelial cells, -dependent coagulant activity (TF activity). The TF activity in bovine endothelial cells (BAECs) was significantly increased i n a concentration-dependent manner by PMNs (1 x 10(5) - 1 x 10(7) cells/ml) without affecting the treatment of N-formyl-methionyl-leucyl-phenylalanine , a selective activator of PMNs, and the addition of PMNs finally resulted in cell damage as evaluated by the lactate dehydrogenase leakage method. In the same conditions, an increase of adhesion between PMNs and BAECs was al so observed in a time-dependent manner. However, since direct adhesion of P MNs to BAECs was impossible by using the transwell, PMNs failed to induce a ny changes in the TF activity. Hence, the change of TF activity found here might be closely related to the PMNs adhesion to BAECs. Indeed, anti-interc ellular adhesion molecule-1 (anti-ICAM-1) antibody blocked the increase of TF activity in BAECs. These findings suggest that PMNs could increase TF ac tivity in endothelial cells, which is triggered by adhesion to endothelial cells through ICAM-1.