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

Short-time exposure to swine dust causes an intense inflammation of upper a nd lower airways and induces increased bronchial responsiveness to methacho line in previously non-exposed healthy volunteers. The objective to this st udy was to investigate the nasal inflammatory response and mucosal reactivi ty to swine dust exposure and whether nitric oxide metabolism is involved i n 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 expo sure to swine dust in a swine confinement building in 17 non-smoking health y 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 gro up 2 (P=0.012). Albumin levels in NAL were higher before as well as after d ust 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 chal lenge 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 t est when performed with connection to each other. The inflammatory reaction may involve NO metabolism.