NITROGEN DIOXIDE-INDUCED EOSINOPHILIA AND MUCOSAL INJURY IN THE NOSE OF THE GUINEA-PIG

Nitrogen dioxide exposure-induced mucosal pathology of the guinea pig nose was studied. Guinea pigs were exposed to 3 ppm or 9 ppm of nitrog en dioxide for 6 h a day,6 times weekly for 2 weeks, and sacrificed 24 h after the final exposure. Exposure to 3 ppm of nitrogen dioxide res ulted in decreased ciliary activity and slight eosinophil accumulation on the epithelium and submucosal layer. More serious pathologies were observed in the nose of guinea pigs exposed to 9 ppm of nitrogen diox ide, including a more prominent eosinophil influx to the epithelium an d epithelial injury due to activation of eosinophils. Epithelial damag e induced by nitrogen dioxide could lead to hyperresponsiveness and ma y result in a prolonged allergic inflammation. Our study suggests that environmental nitrogen dioxide may contribute to hyperresponsiveness and thus be involved in the increased morbidity of allergic rhinitis.