Modulation of pulmonary immune defense mechanisms by sulfuric acid: effects on macrophage-derived tumor necrosis factor and superoxide.

There is considerable interest in the potential health effects resulting from inhalation of acidic aerosols. However, except for well documented irritant effects and acid-induced changes in lung clearance function, other potential health effects have not been well defined. This study was designed to provide further insight regarding the relationship of sulfuric acid aerosol to the pathogenesis of respiratory disease by describing the effects of inhaled acid on the release and/or activity of biologically active mediators critical for maintaining pulmonary immunocompetence and resistance against infectious diseases. Results of this study demonstrated that a single inhalation exposure of rabbits to environmentally relevant and higher concentrations of sulfuric acid depresses the release/activity of lipopolysaccharide-stimulated tumor necrosis factor-alpha and also reduces the ability of pulmonary macrophages to produce superoxide anion radical in response to opsonised zymosan. These findings should be considered when evaluating the health risks associated with sulfuric acid exposure.