Abstract

BACKGROUND: Inhalation of swine dust causes airway inflammation with influx of inflammatory cells, predominantly neutrophils, into the lungs. A study was undertaken to determine whether or not exposure to swine dust induces release of interleukin 8 (IL-8) into upper and lower airways and how this possible release is related to cellular influx. A further aim was to study the relationship between the inflammatory response and swine dust exposure. METHODS: Thirty one healthy, non-smoking, previously unexposed subjects were exposed to swine dust during three hours work in a swine house. Bronchoalveolar lavage (BAL) was performed two weeks before and 24 hours after the exposure (n = 16). Nasal lavage and acoustic rhinometry were carried out 1-2 hours before and seven hours after the start of the exposure (n = 31). Exposure measurements were performed with personal sampling equipment. RESULTS: The exposure led to 19-fold and 70-fold increases in the neutrophil concentrations in nasal lavage and BAL fluid, respectively (p < 0.001). In BAL, fluid macrophages, lymphocytes and eosinophils increased significantly. The IL-8 levels in BAL fluid increased from < 31.3 ng/l to 63 (43-109) ng/l (median (25-75th percentile), p < 0.001), and in nasal lavage fluid the concentrations increased from 144 (97-227) ng/l to 1064 (864-1437) ng/l (p < 0.001). IL-8 levels showed a significant correlation with the increase in neutrophils in the nasal lavage fluid but not in the BAL fluid. Acoustic rhinometry demonstrated significant swelling of the nasal mucosa. The air concentration of inhalable dust was 23.3 (20.0-29.3) mg/m3, endotoxin 1.3 (1.1-1.4) micrograms/m3, and muramic acid 0.99 (0.78-2.1) microgram/m3. CONCLUSIONS: The concentration of IL-8 increases in BAL fluid and nasal lavage fluid following exposure to swine dust and may be one of the chemoattractants contributing to the recruitment of neutrophils to the nasal cavity and the alveolar space.