Quantitative analysis of polymorphonuclear leukocyte superoxide anion generation in critically ill children.

Apart from its well-known bactericidal action, superoxide anion produced by activated polymorphonuclear leukocytes is believed to be involved in pathophysiology of diffuse capillary leak syndromes, e.g., adult respiratory distress syndrome and septic shock. Neutrophil NADPH oxidoreductase, the superoxide anion synthetase, was assayed in blood samples from a variety of critically ill children. Neutrophils from patients with evidence of diffuse capillary leak syndrome had significantly depressed enzyme specific activity as compared to neutrophils from healthy controls or intensive care patients without evidence of diffuse capillary leak. These data along with additional in vitro findings support the contention that previously activated granulocytes may be refractory to subsequent activation, and that such behavior may represent an intrinsic defense mechanism to minimize inflammatory amplification autoinjury.