Concomitant increase in neutrophil adhesion to inflammatory peritoneum andremote organs during peritonitis

Background. Neutrophils contribute to the host defense mechanism, but they can cause remote organ injury in peritonitis. The purpose of this study was to examine neutrophil adhesion to the peritoneum and remote organs simulta neously in peritonitis using a fluorescence microscopic method. Study design. Experiment 1: Sprague-Dawley rats (n = 16) were injected intr aperitoneally (ip) with saline solution or 10(5), 10(7), or 10(9) Escherich ia coli. Five hours after challenge, 1 x 10(6) fluorescein-labeled neutroph ils were infused, Two minutes after neutrophil injection, five peritoneal s amples (the greater omentum, mesentery, parietal peritoneum, colon, and ile um), both lungs, the liver, and the right kidney were harvested for countin g of labeled neutrophils under epifluorescent microscopy. Lung myeloperoxid ase (MPO) activity was also determined. Experiment 2: Rats (n = 23) were gi ven 10(9) E. coli ip. Before challenge (6 h) or at 1, 5, or 10 h after chal lenge, labeled neutrophils were infused. Then, the labeled neutrophil numbe rs in organs and lung MPO activities were assessed as described for Experim ent 1. Hemodynamic and arterial blood gas data were also obtained in anothe r set of rats before and at 1, 5, 8 and 10 h after 10(9) E, coli ip challen ge. Results. Experiment 1: The labeled neutrophil numbers in the peritoneum, lu ngs, and kidney showed significant positive correlations with the injected bacterial numbers. Lung MFO also positively correlated with E. coli number and labeled neutrophil number in the lungs. Experiment 2: Labeled neutrophi l numbers in the peritoneum and kidney peaked at 5 h. The pulmonary labeled neutrophil number rose, reaching a plateau at 5 h. No remarkable change wa s observed in the hepatic labeled neutrophil number, There was a positive c orrelation between lung MPO activity and pulmonary labeled neutrophil numbe r. Hemodynamic and blood gas data reflected a hyperdynamic state. Conclusions. Concomitant dose-dependent increases in neutrophil adhesion in the peritoneum, lungs, and kidney were observed in this peritonitis model. Increased neutrophil adhesion was transient in the peritoneum and kidney b ut persistent in the lungs. Strategies modulating neutrophil adhesion in or gans are anticipated to be useful for the treatment of peritonitis. (C) 199 9 Academic Press.