Decreased wound neutrophils and indiscrete margination in the pathogenesis of wound infection.

Overview

To assess the pathogenesis of increased susceptibility to infection and septic death in a rat model, neutrophils (PMNs) in the wound, circulating PMNs, and their in vivo activity were evaluated after 30% and 60% burns. Eight hours after injury there were twice as many PMNs in the wounds of rats that sustained 30% compared with 60% burns. There was no difference between these two groups in the number of circulating PMNs at 2, 4, 6, and 8 hours after injury. In vivo evaluation of PMN response to infusion of F-Met-Leu-Phe revealed that circulating PMNs were more sensitive 4 hours after 60% burns compared with sham burns. At this time PMNs were found to be less sensitive to zymosan-activated serum infusion after 30% burns compared with sham burns. However, the PMNs in rats with 30% burns were more sensitive to this stimulus than were PMNs in rats with 60% injuries. Thus rats with greater injury, known to be more susceptible to wound infection, have fewer PMNs in their wounds 8 hours after injury. This is preceded by an increased sensitivity of PMNs in vivo to bacterial chemotactic factor and a relative increase in sensitivity to wound factors. This unusual finding implicates indiscrete margination as a factor in the pathogenesis of infection.