Time course of interleukin-6 and tumor necrosis factor-alpha increase in serum following inhalation of swine dust

Inhalation of swine dust induces airway inflammation and general symptoms, such as fever and malaise. In the present investigation, the presence and time course of changes in tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in serum were studied to evaluate possible mechanisms by which inhalation of swine dust induces general symptoms. A group of 14 previously nonexposed subjects weighed swine for 3 h. The average +/- SD inhalable dust concentration was 22.4 +/- 4.7 mg/m(3) and endotoxin, 1.2 +/- 0.4 mu g/m(3). TNF-alpha in serum increased from 2.5 (1.8 to 3.1) ng/L (median, interquartile range) before exposure to maximum values 10.0 (4.6 to 15.7) ng/L between 3 and 5 h after the start of exposure. IL-6 increased from less than 1.5 to 21.4 (18.6 to 33.6) ng/L 4 to 11 h after the start of exposure. Maximum IL-6 occurred 1 to 5 h after the maximum TNF-alpha. In many subjects, however, an early rise in IL-6 parallel to the change in TNF-alpha was seen. The results suggest that some of the peripheral reactions to swine dust might be mediated by TNF-alpha and IL-6. The early rise in IL-6 implies multiple origins of the IL-6.