title: Temporal adaptation of neutrophil oxidative responsiveness to n-formyl-methionyl-leucyl-phenylalanine. Acceleration by granulocyte-macrophage colony stimulating factor.
abstract: This investigation was undertaken to clarify the mechanism by which purified recombinant human granulocyte-macrophage colony stimulating factor (GM-CSF) potentiates neutrophil oxidative responses triggered by the chemotactic peptide, FMLP. Previous studies have shown that GM-CSF priming of neutrophil responses to FMLP is induced relatively slowly, requiring 90 to 120 min of incubation in vitro, is not associated with increased levels of cytoplasmic free Ca2+, but is associated with up-regulation of cell-surface FMLP receptors. We have confirmed these findings and further characterized the process of GM-CSF priming. We found that the effect of GM-CSF on neutrophil oxidative responsiveness was induced in a temperature-dependent manner and was not reversed when the cells were washed extensively to remove the growth factor before stimulation with FMLP. Extracellular Ca2+ was not required for functional enhancement by GM-CSF and GM-CSF alone effected no detectable alteration in the 32P-labeled phospholipid content of neutrophils during incubation in vitro. Our data indicate that GM-CSF exerts its influence on neutrophils by accelerating a process that occurs spontaneously and results in up-regulation of both cell-surface FMLP receptors and oxidative responsiveness to FMLP. Thus, the results demonstrate that, with respect to oxidative activation, circulating endstage polymorphonuclear leukocytes are nonresponsive or hyporesponsive to FMLP; functional responsiveness increases dramatically as surface FMLP receptors are gradually deployed after the cells leave the circulation. Thus, as neutrophils mature, their responsiveness to FMLP changes in a manner which may be crucial for efficient host defense. At 37 degrees C, this process is markedly potentiated by GM-CSF. We conclude that endogenous GM-CSF, released systemically or at sites of infection and inflammation, potentially plays an important role in host defense by accelerating functional maturation of responding polymorphonuclear leukocytes.
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002630:Chemotactic Factors / Q000378:metabolism; D003115:Colony-Stimulating Factors / Q000494:pharmacology*; D004357:Drug Synergism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D016209:Interleukin-8; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000378:metabolism / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption / Q000187:drug effects*; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000032:analysis
chemical_list: D002630:Chemotactic Factors; D003115:Colony-Stimulating Factors; D006133:Growth Substances; D016209:Interleukin-8; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D009240:N-Formylmethionine Leucyl-Phenylalanine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor