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 fu nction as receptors for myeloid leukocytes, We have described a panel of monoclonal antibodies which recognize a sialoglycoprotein from huma n neutrophils and HL-60 promyelocytic cells and inhibit adhesion of th ese cells to P-selectin. In this study, we show that the E-selectin re ceptor-globulin (E-selectin Rg) affinity chromatography can isolate sp ecifically 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 ide ntical with the previously characterized glycoprotein ligand for P-sel ectin, 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 aff inity 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 mono clonal antibody blocks adhesion of HL-60 cells and human neutrophils t o E-selectin Rg, Taken together, our results demonstrate that the P- a nd 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-selec tins.