What happens during rolling adhesion of phagocyte extravasation?

Histamine (released by mast cells), TNF-α and LPS cause the release of Weibel-Palade bodies, P-selectin appears on the endothelium. TNF-α and LPS also cause the appearance of E-selectin. P- and E-selectin bind loosely to the leukocytes on the Sialyl-LewisX glycoproteins. the leukocytes roll along the endothelium.