Background: Allergic rhinitis is a chronic inflammatory disease induced by an immunoglobulin (Ig) E–mediated reaction after exposure to an allergen. Many patients with allergic rhinitis and no clinical evidence of asthma show a heightened response to histamine.

Objectives: The aims of the study were to measure changes in markers of airway inflammation in patients with seasonal allergic rhinitis
and estimate changes in bronchial reactivity before and during the pollen season.

Methods: The study sample comprised 22 patients sensitized to grass pollen and 10 healthy volunteers. Based on the results of the bronchial provocation test (BPT) during the pollen season, we divided patients into those with and without bronchial hyperresponsiveness (BHR). We determined changes in nitrite and pH in exhaled breath concentrate (EBC), fraction of exhaled nitric oxide (FENO), blood eosinophil count, and BPT results before and during the pollen season.

Results: In allergic rhinitis patients with BHR, we observed an increase in EBC nitrite(5.44 [2.33] vs 8.57 [3.35] nmol/mL, P=.02) and FENO (20.90 [13.68] vs. 43.40 [31.60] ppb, P=.02) and a decrease in EBC pH (7.07 [0.33] vs. 6.74 [0.28], P=.01) during the pollen season. In allergic rhinitis patients with BHR, the increase in BHR was negatively correlated with increased FENO and EBC nitrite and positively correlated with a decrease in EBC pH during the pollen season.

Conclusions: Our results revealed a relationship between increased BHR in patients with seasonal allergic rhinitis and changes in airway inflammation markers. EBC pH, EBC nitrite concentration, and FENO could act as prognostic markers for identifying patients at risk of developing asthma.

Key words: Allergic rhinitis. Bronchial hyperresponsiveness. Allergic inflammation. Exhaled breath condensate. Exhaled nitric oxide.