Repeated exposure to organic material alters inflammatory and physiological airway responses.

Farmers and smokers are repeatedly exposed to airborne organic material. We hypothesised that farmers and smokers show altered airway responses to inhaled organic, pro-inflammatory agents. A total of 11 farmers, 12 smokers and 12 controls underwent lipopolysaccharide (LPS) bronchial challenge and spent 3 h in a pig barn. Lung function, exhaled nitric oxide and bronchial responsiveness were assessed and nasal lavage fluid and induced sputum were also collected. Symptoms and body temperature were recorded before and after exposures. Following exposure to the pig barn, bronchial responsiveness, exhaled nitric oxide, sputum interleukin (IL)-6, nasal lavage cell count and IL-8 were increased to a greater extent in controls compared to farmers. The sputum IL-6 response was also attenuated in farmers after LPS challenge. The response shown by smokers following exposure to the pig barn was similar to that of controls regarding measurements of exhaled nitric oxide, IL-8 in nasal lavage and IL-6 in sputum, but more similar to farmers concerning bronchial responsiveness and the cell numbers present in nasal lavage. Sputum IL-8 showed a greater increase in smokers than in the other groups following LPS challenge. We conclude that individuals who are repeatedly exposed to organic material develop an adaptation to the effects of acute exposure to inhaled organic material.