Extracellular cytotoxicity by phagocytosing polymorphonuclear neutrophilic leukocytes: Enhancement by a chemotactic stimulus

This study investigated the influence of a chemotactic stimulus on the extracellular cytotoxicity mediated by phagocytosing polymorphonuclear neutrophilic leukocytes (PMN). We used N-formyl-methionyl-leucyl-phenylalanine (FMLP) as chemotactic peptide, opsonized zymosan as phagocytosable particle, and ox red blood cells (ORBC) as extracellular bystander targets. Phagocytosing PMN were found to kill ORBC efficiently, as determined by the ⁵¹Cr-release assay. FMLP, at the concentration of 100 nM, significantly enhanced the target cell lysis. PMN from two patients with chronic granulomatous disease and normal PMN plus catalase or free radical scavengers (mannitol, benzoate, histidine) were completely devoid of cytolytic activity both in the presence and in the absence of FMLP. The results indicate that the target cell lysis by phagocytosing PMN as well as the chemotactic peptide-related amplification of the lysis itself depend on the expression of the PMN oxidative cytotoxic potential. A similar response to a chemotactic stimulus in vivo could provide a mechanism for regulating PMN-dependent cytotoxic and inflammatory processes.