Exhaled nitric oxide, bronchial hyperresponsiveness and spirometric parameters in patients with allergic rhinitis during pollen season.

Allergic rhinitis and asthma share common epidemiological features and inflammatory processes. The aim of the present study was to document the influence of natural allergen exposure in exhaled NO (eNO) and in spirometric parameters of patients with seasonal allergic rhinitis(SAR) and to investigate the differences among subjects with positive versus negative bronchial provocation to metacholine(BPMch).Twenty-six non-smoking patients (13F/13M; mean age 28.