The Journal of immunology : official journal of the American Association of Immunologists
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The hypothesis that cytokines mediate neutrophil emigration induced by endotoxin (LPS) was studied by examining the potency, the kinetics of neutrophil emigration, and the tachyphylaxis of intradermal sites with IL-1, TNF-alpha and LPS. Human rIL-1 alpha and IL-1 beta, synthetic lipid A, and LPS were several orders of magnitude more potent than human rTNF. The kinetic profiles of neutrophil emigration induced by IL-1 alpha, TNF, and LPS were characterized by minimal emigration in the first 30 min, followed by rapid and transient emigration. ⋯ With this approach, desensitizing injections of IL-1 alpha diminished the neutrophil accumulation after LPS, and LPS also desensitized sites to IL-1 alpha. However, tachyphylaxis was not observed between TNF and LPS, or between TNF and IL-1 alpha. These data suggest that IL-1, but not TNF, is a potential mediator of LPS-induced neutrophil emigration.