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

Background. Intensive care unit patients as a group ha-ire the highest rate of nosocomial Infections, such as pneumonia, urinary tract infections, and wound infections. The triage of polymorphonuclear neutrophils (PMNs) durin g an acute inflammatory response was investigated to determine if the sever ity of injury or infection contributes to PMN delivery. Methods, A murine cecal ligation and puncture-induced peritonitis model wit h polyvinyl sponge discs were used to collect the PMNs in the abdomen (prim ary site) and in the subcutaneous tissue of the dorsum (remote site). Eight y CD1 mab 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 p lacement in the back alone (CON [control]). After 24 hours, the sponges wer e harvested and the PMNs were collected and counted on a hemocytometer. Results. These data, reported as mean PMN cells x10(5) +/- SEM demonstrated that back sponges contained significantly fewer PMNs in the CLP group (3.2 9 +/- 1.1) than in the CM group (7.77 +/- 1.61, P = .04), the SP group (8.6 9 +/- 1.67, P = .01), and the CON group (11.04 +/- 1.91, P < .001). Conclusions. These results demonstrate that PMN delivery to sites of second ary injury are inversely correlated to the severity of the primary injury o r peritonitis.