Mechanisms of human neutrophil oxidant production after severe injury

Background. The Purpose of this study was to determine the mechanisms of en hanced oxidant production after severe injury. Methods. Neutrophils were harvested from patients within 24 hours of admiss ion who had an injury severity score greater than 16. Nonadherent and adher ent neutrophil oxidant production was measured after N-formyl-methionyl-leu cyl-phenylalanine (fMLP) stimulation. Translocation of cytochrome b(558) an d cytosolic components p47(phox) and p67(phox) were determined by oxidation -reduction spectroscopy and immunoblotting, respectively. Flow cytometry me asured integrin expression. Integrin and p47(phox) colocalization was exami ned by confocal microscopy. Results. Eighteen patients were studied within 15 +/- 1.4 hours. Four women and 14 men suffered a blunt injury and had a mean injury severity score of 22 (range, 16 to 34). Nonadherent patient neutrophils showed a decrease in fMLP-stimulated oxidant production, whereas adherent neutrophil oxidant pr oduction was increased in both the vehicle control and fMLP-stimulated grou ps. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase components p47(phox) and cytochrome b(558) were mobilized to the plasma membrane, wher eas p67(phox) showed minimal change. Integrin CD11b alpha chain showed a si gnificant increase in expression. Confocal microscopy showed colocalization of p47(phox) and a chain CD11b on the plasma membrane of patient neutrophi ls. Conclusions. Colocalization of NADPH oxidase components and integrins may r egulate the enhanced oxidant production in human neutrophils after severe i njury.