Nitric oxide, IL-6 and IL-13 are increased in the exhaled breath condensates of children with allergic rhinitis

Aim: To evaluate nitric oxide and interleukin (IL)-6, IL-8 and IL-13 in the exhaled breath of children with allergic rhinitis (AR), before and after intranasal allergen exposure. Methods: A total of 49 children with AR – comprising 20 who also had episodic asthma (AR+A) and 29 without asthma (AR) – were compared with 34 healthy controls. Nitric oxide concentrations in exhaled air (eNO) and IL-6, IL-8 and IL-13 in exhaled breath condensates (EBC) were measured in winter, outside the natural allergen exposure season, before and after an intranasal allergen challenge. Results: The mean concentrations of eNO, IL-6 and IL-13 were significantly higher in the two AR groups. The concentration of IL-8 was below the assay detection limit in all EBC samples. The intranasal allergen challenge increased IL-13/EBC levels in both AR groups, but did not influence mean concentrations of eNO, IL-6 or IL-8. No challenge-related changes in IL-13/EBC were observed in the allergen-exposed controls or placebo-exposed children. Conclusion: Despite local application, the intranasal allergen challenge increased IL-13/ EBC concentration in the AR children. As EBC reflects the status of lower airway segments, our observation may support the ‘united airways’ hypothesis, suggesting a functional link between the upper and lower airways.