Airway reactivity and exhaled NO following swine dust exposure in healthy volunteers.

Short-time exposure to swine dust causes an intense inflammation of upper and lower airways and induces increased bronchial responsiveness to methacholine in previously non-exposed healthy volunteers. The objective to this study was to investigate the nasal inflammatory response and mucosal reactivity to swine dust exposure and whether nitric oxide metabolism is involved in the inflammatory process. Nitric oxide in expired air, nasal histamine test (NH), nasal lavage (NAL) and bronchial histamine challenges were studied before and after a 3 h exposure to swine dust in a swine confinement building in 17 non-smoking healthy subjects not previously exposed to farm dust. To detect any interference between NAL and NH, the subjects were divided into two groups: in group 1, NAL was performed after NH and in group 2, NAL preceded NH. Nasal histamine response increased significantly in group 1, but not in group 2 (P=0.012). Albumin levels in NAL were higher before as well as after dust exposure in group 1 compared to group 2 (P=0.036 and 0.015 respectively). Bronchial histamine responsiveness increased following exposure (P= 0.045). Nitric oxide in expired air decreased following bronchial histamine challenge at baseline (P=0.013) but was otherwise unaltered. Short-time exposure to swine dust increases non-specific reactivity of both nose and bronchi. Nasal lavage procedure interferes with nasal histamine test when performed with connection to each other. The inflammatory reaction may involve NO metabolism.