title: Down-modulation of receptors for granulocyte colony-stimulating factor on human neutrophils by granulocyte-activating agents.
abstract: Purified human blood neutrophils were able to bind radioiodinated murine granulocyte-colony-stimulating factor (G-CSF) in a specific manner. This factor has previously been shown to stimulate functional activities of human and murine neutrophilic granulocytes and to be functionally analogous to human-derived CSF beta. The binding of 125I G-CSF to human neutrophils was competed for equally by unlabeled G-CSF and CSF beta but not by other CSF's. Saturation analysis indicated that human neutrophils displayed about 700-1,500 receptors for G-CSF/CSF beta per cell. Three other agents (N-formyl-methionine-leucine phenylalanine, bacterial lipopolysaccharide, and human CSF alpha) known to activate neutrophils did not compete directly for G-CSF binding sites but, in preincubation experiments at 37 degrees C, were able to down-modulate the expression of G-CSF receptors on human neutrophils in a dose- and time-dependent manner. This effect was specific since the same agents have been shown elsewhere to up-regulate the expression of other granulocyte surface antigens and other agents were much less effective at down-modulating G-CSF receptors. Since the granulocyte-activating agents increase the sensitivity of human neutrophils to G-CSF/CSF beta and mimic some of the actions of G-CSF on neutrophils, it is suggested that G-CSF receptor down-modulation might be a mechanism whereby these agents activate G-CSF receptors and thereby exert some of their effects.
mesh_terms: D000818:Animals; D003115:Colony-Stimulating Factors / Q000378:metabolism / Q000494:pharmacology*; D003864:Depression, Chemical; D006098:Granulocytes; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D016184:Receptors, Colony-Stimulating Factor; D013045:Species Specificity
chemical_list: D003115:Colony-Stimulating Factors; D008070:Lipopolysaccharides; D011956:Receptors, Cell Surface; D016184:Receptors, Colony-Stimulating Factor; D009240:N-Formylmethionine Leucyl-Phenylalanine