Cytoskeletal actin: the influence of major burns on neutrophil structure and function

It has been noted that major trauma and burns patients who survive beyond 48 h most frequently succumb to sepsis and multiple organ failure. Furthermore, such patients are usually markedly hypermetabolic and in negative nitrogen balance at the time of their demise. Along with many other systemic and immune dysfunctions, the polymorphonuclear white blood cells in this setting become functionally impaired. Given that the motile white blood cells contain significant proportions of the contractile protein, actin, we speculated that the leucocyte dysfunction might in part be related to the overall systemic catabolism of actin stores. Accordingly, this hypothesis was explored by comparing the functions and cytoskeletal structure of neutrophilic leucocytes from normal control adults and victims of fresh, major thermal injuries. On days 1 and 7 after a burn of > 25 per cent of total body surface area, peripheral blood was drawn from 10 patients (mean age 33 years, mean burn area 44.2 per cent), and seven unburned controls (mean age 35.2 years). Neutrophils isolated from these specimens were tested for stimulated chemotactic rate, efficacy of intracellular killing as determined by superoxide production rate, and the levels of soluble and insoluble intracellular actin. In addition, both light microscopy and scanning electron microscopy were used to visualize the actin cytoskeleton. The results indicated that both chemotactic rate (12 mu/min vs. 38 mu/min--P < 0.05) and superoxide production rate (9 vs 43 mumol/ml10E6 cells--P < 0.05), were significantly reduced in the burn patients by day 7.(ABSTRACT TRUNCATED AT 250 WORDS)