Epidermal growth factor enhances TNF-α-induced priming of human neutrophils

The intensity of neutrophil inflammatory response could be rapidly amplified by priming with pro-inflammatory mediators such as TNF-α, GM-CSF or LPS at low concentrations prior to stimuli. We proposed that epidermal growth factor (EGF) increases TNF-α-induced priming of human neutrophils. This study showed that EGF enhanced TNF-α-induced activation of neutrophils functions. The addition of EGF to neutrophils cultured with TNF-α resulted in increased respiratory burst and phagocytic activity of polymorphonuclear leukocytes (PMN) and up-regulation of adhesion molecule CD11b. Moreover, EGF enhanced IL-8 production by TNF-α-primed PMN. EGF alone was able to prime CD11b expression and IL-8 production by PMN. EGF receptor selective tyrosine kinase inhibitor, tyrphostin AG-1517, blocked the effect of priming with EGF, whereas the status of non-primed and TNF-α-primed neutrophils remained unaffected. EGFR expression on neutrophils was confirmed by flow cytometry and CELISA methods. These data provide the original evidence that EGF significantly enhances TNF-α-induced priming of human neutrophils acting through EGFR tyrosine kinase pathway. The observed effect may be a result of co-operative action of EGF, TNF-α and reactive oxygen intermediates (ROI).