P-selectin is important in the flow adhesion of sickle erythrocytes to thrombin-stimulated endothelium in vitro.

The number of sickle cells adhering to HUVECs (i) and the rolling velocities of the adhering cells (ii) were examined. (A) In 10 experiments, the rolling adhesion of sickle cells to HUVECs was examined prior to and after treatment of HUVECs with thrombin. The rolling adhesion of sickle cells to thrombin-treated HUVECs was then examined in the presence of anti–P-selectin mAb 9E1. Statistically significant differences compared with untreated HUVECs (*) and to thrombin-treated HUVECs (††) are indicated. (B) In 3 experiments the rolling adhesion of sickle cells to thrombin-treated HUVECs also was examined in the presence of nonblocking anti–P-selectin mAb AC1.2. Statistically significant differences compared with untreated HUVECs (*) and to thrombin-treated HUVECs (†) are indicated. (C) In 10 experiments the firm adhesion of sickle cells to HUVECs was examined prior to and after treatment of HUVECs with thrombin. Statistically significant differences (*) are indicated.