The CD62P (HI62P) antibody recognizes a 140-kDa long single chain type-I transmembrane glycoprotein, P-selectin, also called granule membrane protein-140 (GMP-140) or platelet activation dependent granule-external membrane protein (PADGEM). CD62P antigen is present in the α-granules of platelets and in Weibel-Palade bodies of endothelial cells, and is rapidly mobilized from storage granules to the cell surface after cell activation. CD62P is expressed on the surface of the activated platelets. Interaction of CD62P with PSGL-1 (CD162) mediates tethering and rolling of leukocytes on the surface of activated endothelial cells, the first step in leukocyte extravasation and migration towards sites of inflammation. CD62P also mediates rolling of platelets on endothelial cells and CD62P-mediated interactions involved in platelet-mediated delivery of lymphocytes to high endothelial venules (HEV). Defects in CD62P is a cause of susceptibility to ischemic stroke.