Neutrophil disorders in burn injury: complement, cytokines, and organ injury

Because of the association of burn injury with subsequent bacterial infection, numerous studies have been performed characterizing neutrophil function in burn injury. These studies provide a picture of intravascular complement activation, neutrophil-C5a interactions, and consequent disordered cellular function. Neutrophil dysfunction includes suppressed random and C5a-directed migration and hyperresponsiveness to oxidative stimuli. These observations do not explain the histologic and functional involvement of neutrophils in ARDS and perhaps other organ failure states. Circumstantial and extrapolated information suggests that macrophage-lineage cells function as regulators of neutrophil function within matrix environments in burn injury. Elevated endotoxin levels have been found in burned patients, which would support the notion of endotoxin-stimulated monocytes/macrophages as inducing neutrophil migration into connective tissue matrices (LTB4 and IL-8), inducing prolonged oxidant production (TNF-alpha, GM-CSF), and inducing neutrophil release of regulatory substances from neutrophils (G-CSF). This information suggests a variety of experimental approaches to testing this hypothesis.