Plasma C3d levels of young farmers correlate with respirable dust exposure levels during normal work in swine confinement buildings

Work in swine confinement buildings leads to an inflammatory response and may be associated with increased levels of acute phase proteins. We compared the inflammatory response of a control group of young former farm workers with age-matched former farm workers who had previously developed the lower airway symptoms of wheeze, cough, tightness of the chest during work in swine confinement buildings, and because of these symptoms had stopped work. Both groups were subjected to an experimental exposure in a swine confinement building for 3 hours. Complement activation and acute phase proteins were measured in blood samples and broncho-alveolar lavage. Plasma C3d levels correlated with respirable dust, significantly so for individual cases and for the whole cohort. Plasma C3, fibrinogen and alpha (1) -acid glycoprotein peaked 1 and 6 h after exposure start, mannan-binding lectin, C-reactive protein and alpha(1)-antitrypsin peaked after 2 h. Surfactant protein D (SP-D) and alpha (2) -macroglobulin were downregulated. In lavage, only SP-D, alpha (2)-macroglobulin and fibronectin were detected. FEV(1), FVC, TLC and FEV(25-75) did not vary during exposure. There was complement activation in response to respiratory dust, more so amongst cases than in the control group. Acute exposure, with work related levels of organic dust containing endotoxin, leads to a weak systemic inflammatory response.