Role of IL-17A and neutrophils in fibrosis in experimental hypersensitivity pneumonitis.

Background: Chronic hypersensitivity pneumonitis is characterized by pulmonary inflammation and fibrosis in response to repeated inhalation of mainly organic antigens. It is recognized that IL-17A is crucial for the development of pulmonary inflammation in murine models of experimental hypersensitivity pneumonitis, but its role in the development of pulmonary fibrosis has not been determined. Furthermore, the main cell type(s) that produce IL-17A in experimental hypersensitivity pneumonitis have not yet been identified.