Acid aspiration-induced acute lung injury causes leukocyte-dependent systemic organ injury

The adult respiratory distress syndrome is a form of acute lung injury (ALI) that is frequently associated with systemic organ injury and often occurs in the setting of wide-spread inflammatory cell activation. However, whether conditions that lead to ALI result in systemic organ injury is unclear. This study was designed to test the hypothesis that ALI induced by acid aspiration will not result in systemic organ injury. Morphological alterations and lymph-to-plasma protein ratios were measured in autoperfused cat ileum preparations of four control animals and five animals with ALI produced by the endobronchial instillation of 0.1 N HCl (0.5 ml.kg-1.lung-1). After 2 h, the lymph-to-plasma protein ratio (a measure of microvascular permeability) was increased in the ilea of HCl-injured animals compared with control animals (0.234 +/- 0.03 vs. 0.121 +/- 0.005; P = 0.012) and was accompanied by extensive morphological alterations. Four additional HCl-injured animals were pretreated with an antileukocyte adherence antibody (anti-CD18, 2 mg/kg) that blocked the HCl-induced alterations in the ileum. This study provides evidence for significant systemic organ injury after acid aspiration-induced ALI and suggests that the neutrophil may be a key mediator.