Nitrogen dioxide modifies allergic inflammation in tracheal mucosa

Our study was designed to investigate the possible role of nitrogen dioxide exposure in respiratory allergic disorders. Guinea pigs were treated with a combination of passive sensitization, antigen challenge and nitrogen dioxide exposure. Nitrogen dioxide accumulated eosinophils to the epithelium of the trachea. Neither passive sensitization nor antigen challenge with nitrogen dioxide exposure developed more prominent pathological changes than nitrogen dioxide exposure alone. However, antigen--antibody interaction with nitrogen dioxide exposure resulted in a disruption of epithelial cells so prominent that the basement membrane was denuded in areas. Activated eosinophils and free eosinophil-specific granules were considered to be responsible for the extreme epithelial injury. In conclusion, nitrogen dioxide exposure does not cause prominent epithelial injury by itself, but could be a trigger for hyperresponsiveness in allergic airways, and is probably involved in the pathogenesis of airway allergic disorders.