Modulation of Pulmonary Defense Mechanisms against Viral and Bacterial Infections by Acute Exposures to Nitrogen Dioxide

摘要

Levels of nitrogen dioxide (NO2) exposure that induce increased susceptibility to viral and bacterial infections were studied in the murine animal mode. Physiological parameters of host resistance to respiratory infections were used as endpoints. The salient findings were: (1) intrapulmonary killing of staphylococcus aureus was impaired at 5.0 ppm of NO2; (2) this effect was found at 2.5 ppm when NO2 exposure was superimposed on immunosuppressed lungs treated with corticosteroids; (3) the adverse effect of NO2 occurred at lower concentration when exposure followed bacterial challenge; and (4) during the course of murine Sendai virus infection, NO2 exposure did not alter the infection in the lungs but did enhance lung pathology. The implications of these findings are that the antibacterial defenses of the lungs are susceptible to the inhibiting effects of acute exposures of lower concentrations of NO2 when the lungs are predisposed by bacteria immunosuppression. The alveolar macrophage phagocytic system is the defense component most susceptible to the adverse effects of NO2. (Copyright (c) 1988 Health Effects Institute.)