Selectins & Their Clinical Importance. Selectins are cell surface lectins that have evolved to mediate the adhesion of leukocytes to endothelial cells and platelets under flow. Three selectins have been identified: L-selectin (leukocyte selectin), P-selectin (platelet selectin), and E-selectin (endothelial selectin). In collaboration with other CAM families, selectins play important roles in leukocyte trafficking to the sites of inflammation. | Dr. Najeeb