THE P-SELECTIN GLYCOPROTEIN LIGAND FUNCTIONS AS A COMMON HUMAN-LEUKOCYTE LIGAND FOR P-SELECTINS AND E-SELECTINS

P- and E-selectins belong to a family of Ca2+-dependent lectins and function as receptors for myeloid leukocytes, We have described a panel of monoclonal antibodies which recognize a sialoglycoprotein from human neutrophils and HL-60 promyelocytic cells and inhibit adhesion of these cells to P-selectin. In this study, we show that the E-selectin receptor-globulin (E-selectin Rg) affinity chromatography can isolate specifically only one glycoprotein from [H-3] glucosamine-labeled HL-60 cells in a Ca2+-dependent manner. This protein has a molecular mass of similar to 120 kDa under reducing conditions, which appears to be identical with the previously characterized glycoprotein ligand for P-selectin, The molecule can be cross-depleted by and cross-bound to the E- and P-selectin columns, The chromatographic profile of desialylated O-linked carbohydrates from molecules purified by P- and E-selectin affinity chromatography are identical, Both have five structures at 12.8, 9.8, 6.3, 3.5, and 2.5 glucose units, PL5 monoclonal antibody to the P-selectin sialoglycoprotein ligand, E-selectin Rg, and antiserum to P-selectin glycoprotein ligand-1 (PSGL-1) all recognize the purified P-selectin ligand on ligand blots and immunoblots. Furthermore, PL5 monoclonal antibody blocks adhesion of HL-60 cells and human neutrophils to E-selectin Rg, Taken together, our results demonstrate that the P- and E-selectin ligand defined in this study is PSGL-1 and suggest that this molecule is an important leukocyte ligand for both P- and E-selectins.