title: differential L-selectin binding activities of human hematopoietic cell L-selectin ligands, HCELL and PSGL-1.
abstract: Expression of L-selectin on human hematopoietic cells (HC) is associated with a higher proliferative activity and a more rapid engraftment after hematopoietic stem cell transplantation. Two L-selectin ligands are expressed on human HCs, P-selectin glycoprotein ligand-1 (PSGL-1) and a specialized glycoform of CD44 (hematopoietic cell E- and L-selectin ligand, HCELL). Although the structural biochemistry of HCELL and PSGL-1 is well characterized, the relative capacity of these molecules to mediate L-selectin-dependent adhesion has not been explored. In this study, we examined under shear stress conditions L-selectin-dependent leukocyte adhesive interactions mediated by HCELL and PSGL-1, both as naturally expressed on human HC membranes and as purified molecules. By utilizing both Stamper-Woodruff and parallel-plate flow chamber assays, we found that HCELL displayed a 5-fold greater capacity to support L-selectin-dependent leukocyte adherence across a broad range of shear stresses compared with that of PSGL-1. Moreover, L-selectin-mediated leukocyte binding to immunopurified HCELL was consistently >5-fold higher than leukocyte binding to equivalent amounts of PSGL-1. Taken together, these data indicate that HCELL is a more avid L-selectin ligand than PSGL-1 and may be the preferential mediator of L-selectin-dependent adhesive interactions among human HCs in the bone marrow.
authors.affiliation: Department of Dermatology, Harvard Skin Disease Research Center, Brigham and Women's Hospital, Harvard Medical School, 77 Ave. Louis Pasteur, Boston, MA 02115, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Dimitroff
authors.forename: J Y
authors.initials: JY
authors.lastname: Lee
authors.forename: K S
authors.initials: KS
authors.lastname: Schor
authors.forename: B M
authors.initials: BM
authors.lastname: Sandmaier
authors.forename: R
authors.initials: R
authors.lastname: Sackstein
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000378:metabolism; D016466:CHO Cells; D002448:Cell Adhesion; D002460:Cell Line; D006224:Cricetinae; D000939:Epitopes / Q000378:metabolism; D005434:Flow Cytometry; D006023:Glycoproteins / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D018960:Hyaluronan Receptors / Q000737:chemistry / Q000378:metabolism*; D019041:L-Selectin / Q000737:chemistry / Q000378:metabolism*; D007962:Leukocytes / Q000378:metabolism; D008024:Ligands; D008214:Lymphocytes / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D019007:P-Selectin / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013312:Stress, Physiological; D013997:Time Factors; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D006023:Glycoproteins; D018960:Hyaluronan Receptors; D019041:L-Selectin; D008024:Ligands; D008562:Membrane Glycoproteins; D019007:P-Selectin; C084882:P-selectin ligand protein; C497483:CD44 protein, human