Activation of neutrophils by cachectin/tumor necrosis factor: priming of N-formyl-methionyl-leucyl-phenylalanine-induced oxidative responsiveness via receptor mobilization without degranulation

Abstract

Human recombinant cachectin/tumor necrosis factor (TNF) was shown to prime neutrophils (PMNs), in a dose-dependent fashion, for subsequent oxidative responsiveness toward n-formyl-methionyl-leucyl-phenylalanine (FMLP). One basis for this phenomenon appeared to be TNF-mediated FMLP receptor mobilization. The maximal observed priming response was associated with a nearly twofold increase in the expression of PMN FMLP surface receptors, without changes in receptor affinity. Priming was not seen following stimulation with phorbol myristate acetate, possibly eliminating a role for the protein kinase C-dependent transductional components of FMLP-induced oxidative activity in the priming process. FMLP receptor mobilization occurred without significant degranulation as evident by an absence of increased granular enzyme release. These data support a potential role of macrophage-derived TNF in the augmentation of PMN host-defense during infectious and inflammatory challenge. TNF-mediated PMN oxidative priming may also promote oxidant tissue injury as seen in septic shock, adult respiratory distress syndrome, and multiple system organ failure.