Polymorphonuclear neutrophil (PMN) recruitment in a 2-front murine injury model: Triage of PMNs to competing stimuli of recruitment

Abstract

Background: Intensive care unit patients as a group have the highest rate of nosocomial infections, such as pneumonia, urinary tract infections, and wound infections. The triage of polymorphonuclear neutrophils (PMNs) during an acute inflammatory response was investigated to determine if the severity of injury or infection contributes to PMN delivery. Methods: A murine cecal ligation and puncture-induced peritonitis model with polyvinyl sponge discs were used to collect the PMNs in the abdomen (primary site) and in the subcutaneous tissue of the dorsum (remote site). Eighty CD1 male mice—20 in each of 4 groups—were assigned to the following: cecal ligation and puncture (CLP), sham laparotomy with cecal manipulation (CM), polyvinyl sponge placement in the abdomen and back only (SP), and sponge placement in the back alone (CON [control]). After 24 hours, the sponges were harvested, and the PMNs were collected and counted on a hemocytometer. Results: These data, reported as mean PMN cells × 105 ± SEM, demonstrated that back sponges contained significantly fewer PMNs in the CLP group (3.29 ± 1.1) than in the CM group (7.77 ± 1.61, P =.04), the SP group (8.69 ± 1.67, P =.01), and the CON group (11.04 ± 1.91, P <.001). Conclusions: These results demonstrate that PMN delivery to sites of secondary injury are inversely correlated to the severity of the primary injury or peritonitis. (Surgery 2000;127:323-8.)