title: Development of specific functionally active receptors for platelet-activating factor in HL-60 cells following granulocytic differentiation.
abstract: A human promyelocytic leukemia cell line (undifferentiated HL-60 cells) as well as a granulocyte form of HL-60 cells induced in vitro by exposure to dimethyl sulfoxide were examined for binding, metabolism, and biological responses to platelet-activating factor (PAF). Undifferentiated and differentiated HL-60 cells each exhibit a high capacity to incorporate and metabolize [3H]PAF at 37 degrees C; however, the amount of [3H]PAF that is assimilated by both cell populations is greatly reduced and its metabolism abolished at less than or equal to 4 degrees C. At 0 degrees C HL-60 granulocytes bind more [3H]PAF than their undifferentiated counterparts. Binding to differentiated cells reaches equilibrium within 80 min and is saturable, reversible and specific; PAF receptor antagonists WEB 2086, L-659,989, BN 52021, and kadsurenone abolish this specific [3H]PAF binding. In contrast, [3H]PAF uptake by undifferentiated HL-60 cells is neither saturable nor sensitive to specific receptor antagonists. Scatchard analyses reveal 5850 +/- 850 binding sites per differentiated HL-60 cell with a dissociation constant of 0.66 +/- 0.15 nM. In the presence of cytochalasin B, PAF (200 nM) induces degranulation only in differentiated cells and this response also is blocked by PAF receptor antagonists. Our results demonstrate that HL-60 cells develop specific and functionally active PAF receptors only after chemically induced differentiation into granulocytes.
authors.affiliation: Medical Sciences Division, Oak Ridge Associated Universities, Tennessee 37831-0117.
authors.forename: D S
authors.initials: DS
authors.lastname: Vallari
authors.forename: R
authors.initials: R
authors.lastname: Austinhirst
authors.forename: F
authors.initials: F
authors.lastname: Snyder
mesh_terms: D000118:Acetylglucosaminidase / Q000378:metabolism; D001667:Binding, Competitive; D002454:Cell Differentiation; D003571:Cytochalasin B / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D006098:Granulocytes / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D015473:Leukemia, Promyelocytic, Acute; D009113:Muramidase / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D010972:Platelet Activating Factor / Q000378:metabolism* / Q000494:pharmacology; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D014407:Tumor Cells, Cultured
chemical_list: D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D003571:Cytochalasin B; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009113:Muramidase; D000118:Acetylglucosaminidase; D004121:Dimethyl Sulfoxide