Inhalation of swine-house dust increases the concentrations of interleukin-1 beta (IL-1β) and interleukin-1 receptor antagonist (IL-1ra) in peripheral blood

Abstract

Inhalation of dust in swine confinement buildings causes airway inflammation and systemic symptoms. The proinflammatory cytokines interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) increase in bronchoalveolar and nasal lavage fluid, and in serum. The aim of this investigation was to study changes in the IL-1 family of cytokines in peripheral blood in 36 healthy volunteers exposed to swine house dust for 3 h. Interleukin (IL-1β) was measured in platelet poor plasma and in a mononuclear cell fraction (PBMC) and interleukin-1 receptor antagonist (IL-1ra), IL-6 and TNF-α were measured in serum 4 and 7 h after the start of 3 h exposure. Lung function and a methacholine bronchial provocation test were performed before and 7 h after the start of exposure. The leukocyte count in whole blood and the mononuclear cell count in PBMC were examined before, and 4 and 7 h after the start of exposure. The concentration of airborne inhalable dust and endotoxin were measured using personal samples. The concentration of inhalable dust was 23 (20–30) mg m −3 (median 25th–75th percentile) endotoxin was 1·1 (0·8–1·4) μg m −3 and respirable dust ( n=8) was 1·0 (0·7–1·2) mg m −3. IL-1β increased from <0·125 to 0·9 (0·5–1·3) ng l −1 in plasma and from 1·6 to 2·7 (1·1–4·4) ng l −1 in PBMC ( P<0·01). IL-1ra, IL-6 and TNF-α increased 2-, 12- and 2-fold in serum after exposure, respectively. Changes in IL-1ra correlated with changes in FEV 1, bronchial responsiveness, oral temperature ( P<0·01) and blood white cell count ( P<0·05). IL-1β correlated significantly with temperature ( P<0·05). These results indicate that IL-1β and IL-1ra increase in peripheral blood following inhalation of swine house dust and may participate in and modulate the inflammatory response together with IL-6 and TNF-α.