Does Nitrogen Dioxide Affect Inflammatory Markers after Nasal Allergen Challenge?

Abstract

Background

Exposure to high ambient levels of nitrogen dioxide (NO₂) enhances the bronchial inflammatory reaction to allergen in humans. We tested whether this NO₂ effect occurs also in the upper airways.

Methods

Sixteen allergic subjects with rhinitis and mild asthma were exposed at rest to either purified air or 500 μg/m³ NO₂ for 30 minutes, followed 4 hours later by a nasal allergen challenge. Nasal lavage was performed before air/NO₂ exposure, before allergen challenge, and 1, 4 and 18 hours after allergen challenge. Symptoms were recorded.

Results

The percentage of eosinophils and neutrophils, eosinophil cationic protein, and myeloperoxidase were similar after exposure to air + allergen and to NO₂ + allergen. We noticed a tendency to increased sneezing the day after exposure to NO₂ + allergen.

Conclusion

The priming effect of an ambient brief NO₂ exposure on subsequent allergic response was not noticeable in activation of inflammatory cells and mediators in the upper airways.