title: Primitive human hematopoietic progenitors adhere to P-selectin (CD62P).
abstract: P-selectin was shown to bind committed human hematopoietic progenitors (colony-forming unit-granulocyte-macrophage [CFU-GM] and burst-forming unit-erythroid [BFU-E]) as identified by their expression of the CD34 antigen and by in vitro clonogenic assays. In addition, P-selectin bound all precursors (pre-CFU) of committed myeloid progenitors assayed by their ability to sustain hematopoiesis in both conventional stroma-containing and stroma-free, cytokine-dependent systems. Binding of CD34+ cells to P-selectin was temperature-independent and shear-resistant, occurred only in the presence of divalent cations, was protease sensitive, and was completely blocked by anti-P-selectin antibody. Neuraminidase treatment of CD34+ cells completely abrogated their binding to P-selectin, implying a prominent role for sialic acid in the structure and function of the P-selectin ligand on hematopoietic progenitors. Monoclonal antibodies (MoAbs) CSLEX-1 and HECA-452, which identify carbohydrate epitopes involving sialic acid, bound to 33% and 35% of CD34+ cells, respectively, and included the majority of CFU-GM and pre-CFU. Three-color flow cytometric analysis showed a precise codistribution of CSLEX-1 and HECA-452 antigens on CD34+ cells, implying recognition of the same glycoprotein antigen by the two MoAbs. Treatment of CD34+ cells with neuraminidase completely abolished binding of both MoAbs. In addition, HECA-452 partially blocked the adhesion of CD34+ cells to P-selectin. P-selectin glycoprotein ligand (PSGL-1), recently molecularly cloned from the promyelocytic leukemia cell line HL60, was expressed by CD34+ cells as determined by reverse transcription polymerase chain reaction. Combined with the functional and biochemical characteristics, these data suggest that PSGL-1 may comprise an important P-selectin ligand expressed by primitive hematopoietic cells, but do not preclude the existence of additional P-selectin ligands on these cells.
authors.affiliation: Leukaemia Research Unit, Hanson Centre for Cancer Research, Adelaide, South Australia.
authors.forename: A C
authors.initials: AC
authors.lastname: Zannettino
authors.forename: M C
authors.initials: MC
authors.lastname: Berndt
authors.forename: C
authors.initials: C
authors.lastname: Butcher
authors.forename: E C
authors.initials: EC
authors.lastname: Butcher
authors.forename: M A
authors.initials: MA
authors.lastname: Vadas
authors.forename: P J
authors.initials: PJ
authors.lastname: Simmons
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis / Q000276:immunology*; D018952:Antigens, CD34; D001483:Base Sequence; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells; D002448:Cell Adhesion; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins / Q000276:immunology*; D016133:Polymerase Chain Reaction; D012313:RNA / Q000032:analysis
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins; D012313:RNA