English D, Broxmeyer H E, Gabig T G, Akard L P, Williams D E, Hoffman R
Department of Medicine, Indiana University School of Medicine, Indianapolis 46223.
J Immunol. 1988 Oct 1;141(7):2400-6.
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.
进行这项研究是为了阐明纯化的重组人粒细胞-巨噬细胞集落刺激因子（GM-CSF）增强趋化肽FMLP触发的中性粒细胞氧化反应的机制。先前的研究表明，GM-CSF引发中性粒细胞对FMLP的反应相对较慢，体外孵育需要90至120分钟，与细胞质游离Ca2+水平升高无关，但与细胞表面FMLP受体上调有关。我们证实了这些发现，并进一步对GM-CSF引发过程进行了表征。我们发现GM-CSF对中性粒细胞氧化反应性的影响是以温度依赖的方式诱导的，在用FMLP刺激前广泛洗涤细胞以去除生长因子时，这种影响不会逆转。GM-CSF增强功能不需要细胞外Ca2+，单独的GM-CSF在体外孵育期间对中性粒细胞32P标记的磷脂含量没有可检测到的改变。我们的数据表明，GM-CSF通过加速一个自发发生的过程来影响中性粒细胞，该过程导致细胞表面FMLP受体上调以及对FMLP的氧化反应性增强。因此，结果表明，就氧化激活而言，循环中的终末多形核白细胞对FMLP无反应或反应低下；随着细胞离开循环后表面FMLP受体逐渐展开，功能反应性会显著增加。因此，随着中性粒细胞成熟，它们对FMLP的反应性以一种可能对有效的宿主防御至关重要的方式发生变化。在37摄氏度时，GM-CSF可显著增强这一过程。我们得出结论，全身或在感染和炎症部位释放的内源性GM-CSF可能通过加速反应性多形核白细胞的功能成熟在宿主防御中发挥重要作用。
