Exhaled nitric oxide in asthmatic children and adolescents after nasal allergen challenge.

Epidemiological data suggest a comorbidity link between nasal and bronchial allergic disease. Exhaled nitric oxide (FENO) is a sensitive marker of bronchial inflammation and increases after bronchial allergen provocation. We studied FENO in 19 children and adolescents with allergic asthma and 10 controls before and 2, 6 and 24 h after a single nasal allergen challenge. The correlation between FENO and other markers of allergic inflammation, such as eosinophils in blood and eosinophil cationic protein (ECP) in serum and nasal lavage was also assessed. FENO remained unchanged 24 h post-challenge in both steroid and steroid-naive patients. At 6 h post-challenge, FENO decreased in both asthmatics and controls. The asthmatic subjects showed a positive correlation between FENO and blood eosinophils before (r=0.71, p=0.001) and after the challenge, and between FENO and ECP in nasal lavage (r=0.62, p=0.02) 2 h after the challenge. Mean ECP in nasal lavage increased post-challenge but not significantly. We conclude that a single nasal allergen challenge does not augment bronchial inflammation although FENO, is related to blood eosinophil count and to the nasal inflammatory response. Our data do not support the theory of a direct transmission of the nasal inflammation to the lower airways.