Figure 14.

Rolling of platelets on vascular surfaces. (a) After vascular injury, platelets tether to and roll (translocate) on subendothelial matrices through interactions of platelet GPIbα with VWF. Signaling during rolling activates platelet β₁ and β₃ integrins, which mediate arrest and aggregation. (b) Unstimulated platelets roll on P-selectin on activated endothelial cells, probably through interactions with GPIbα. Activated platelets use P-selectin to roll on PNAd or PSGL-1 expressed on some endothelial cells and on PSGL-1 expressed on leukocyte fragments bound to the endothelial cell surface. Activated platelets bound to leukocytes roll together on endothelial cells.