Nitric oxide attenuates interleukin 2-induced lung injury

Background. The pathogenesis of interleukin (IL) 2-induced vascular leak syndrome may be related to neutrophil-mediated endothelial injury. Nitric oxide inhibits neutrophil superoxide anion synthesis and adherence to endothelial cells. The role of systemic nitric oxide in preventing IL-2-induced lung injury was studied in an experimental model. Methods. Sprague-Dawley rats (seven per group) were randomized to control, IL-2 treatment (1 x 10⁶ units), and IL-2 with sodium nitroprusside 0.2 mg/kg. Lung injury was measured by estimation of extravascular lung water (wet:dry weight) and bronchoalveolar lavage (BAL) protein concentration, and by histological findings. Neutrophil infiltration was evaluated by measuring myeloperoxidase activity and BAL neutrophil concentration. Results. IL-2 produced significant lung damage characterized by leucocyte sequestration (increased myeloperoxidase and BAL neutrophil concentrations), pulmonary congestion and microvascular protein leakage (increased wet:dry weight ratio and BAL protein concentration). This injury was reduced significantly by the addition of sodium nitroprusside, the nitric oxide donor. Conclusion. Nitric oxide reduces IL-2-induced lung injury.