The intravenous administration of tumor necrosis factor alpha,interleukin 8 and macrophage-derived neutrophil chemotactic factor inhibits neutrophil migration by stimulating nitric oxide production

1. The i.v. administration of tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8) and the recently described macrophage-derived neutrophil chemotactic factor (MNCF) inhibits the recruitment of neutrophils to the inflammatory site.
2. Pretreatment of mice with the NO synthase antagonist, N^G-monomethyl-L-arginine (L-NMMA, 15–60 mg kg⁻¹), but not the inactive enantiomer D-NMMA (30 mg kg⁻¹), prevented in a dose-dependent manner the TNF-α, IL-8 and MNCF-mediated inhibition of neutrophil migration into thioglycollate-challenged peritoneal cavities.
3. Treatment of the neutrophils with TNFα (10⁻⁷ M), IL-8 (10⁻⁷ M) or MNCF blocked their migration towards FMLP in the chemotaxis assay. The pretreatment of the neutrophils with L-NMMA (50–200 μM) prevented in a dose-dependent manner the inhibition of FMLP-induced chemotaxis by IL-8, but did not alter the inhibition caused by TNF-α or MNCF. Different concentrations of the NO donors, S-nitroso-N-acetylpenicillamine (SNAP) or 3-morpholino-sydnonimine (SIN-1), did not alter this chemotaxis.
4. Preincubating the neutrophils with L-NMMA (200 μM) significantly increased the TNF-α (10⁻⁷ M) and MNCF-mediated neutrophil adhesion to unstimulated endothelial cells, but had no effect on IL-8 (10⁻⁷ M)-mediated adhesion.
5. Although NO donors did not directly affect the mechanisms of neutrophil motility, NO is involved in the in vitro inhibitory action of IL-8 on chemotaxis. The TNF-α and MNCF-mediated inhibition of neutrophil migration seems to be indirect, by affecting the mechanisms of adhesion. It was concluded that TNF-α-, IL-8- and MNCF-mediated inhibition of neutrophil migration is associated with the stimulation of NO production.