Lung cell oxidant injury: decrease in oxidant mediated cytotoxicity by N-acetylcysteine.

Lung cell damage mediate by polymorphonuclear leukocyte (PMN) reactive oxygen metabolites has been suggested as a pathophysiologic mechanism in a variety of acute and chronic pulmonary disease states, while oxidant injury may be a non-specific cytotoxic mechanism. Reducing agents therefore represent one therapeutic direction for decreasing lung cell injury in several clinical circumstances. N-Acetylcysteine (NAC) is a known antioxidant which can be distributed in soluble form to multiple intrapulmonary sites. We have therefore examined a possible role for NAC against oxidant injury in a controlled in vitro model for oxygen metabolite cytotoxicity. Our data suggest that extracellular NAC is able to protect lung cells against PMN mediated oxidant injury. Pre-exposure of lung cells to NAC results in decreased susceptibility to oxidant damage by increasing intracellular antioxidant defense systems. An increase in extracellular and/or intracellular resistance to toxic oxygen metabolites by NAC may be one approach to the prevention of in vivo lung oxidant injury.