Chronic hypersensitivity pneumonitis caused by Saccharopolyspora rectivirgula is not associated with a switch to a Th2 response

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease that develops following repeated exposure to inhaled environmental antigens. The disease results in alveolitis and granuloma formation and may progress to a chronic form associated with fibrosis; a greater understanding of the immunopathogenic mechanisms leading to chronic HP is needed. We used the Saccharopolyspora rectivirgula (SR) mouse model of HP to determine the extent to which a switch to a Th2-type immune response is associated with chronic HP. Exposure of wild-type (WT) and tlr2/9−/− mice to SR for 14 wk resulted in neutrophilic and lymphocytic alveolitis that was not dependent on Toll-like receptors (TLRs) 2 and 9. Long-term exposure of WT mice to SR resulted in a significant increase in collagen deposition, protein leakage, and IL-1α accompanied by a decrease in quasistatic compliance and total lung capacity compared with unexposed mice. This was associated with an increase in IL-17 but not IL-4 production or recruitment of Th2 cells. tlr2/9−/− mice exhibited an increase in protein leakage but less IL-1α and collagen deposition in the lungs compared with WT mice, yet they still displayed a decrease in quasistatic compliance, although total lung capacity was not affected. These mice exhibited an increase in both IL-13 and IL-17, which suggests that IL-13 may ameliorate some of the lung damage caused by long-term SR exposure. Our results suggest that lung pathology following long-term SR exposure in WT mice is associated with the IL-17 response and that TLRs 2 and 9 may inhibit the development of the IL-13/Th2 response.

Assessment of four serological techniques in the immunological diagnosis of farmers' lung disease

Farmers' lung disease (FLD) is a pulmonary disease that results from repeated inhalation of antigens from mouldy hay or straw. The objective of this prospective study was to assess the reliability of four serological techniques in FLD diagnosis. Sera from 15 consecutive patients with FLD, 15 healthy control farmers and 30 urban controls were analysed using four serological techniques [electrosyneresis (ES), Ouchterlony double diffusion (DD), ELISA and Western blot (WB)] with four antigens (Absidia corymbifera, Eurotium amstelodami, Wallemia sebi and Saccharopolyspora rectivirgula). In the authors' region, ES on cellulose acetate with A. corymbifera antigen was the most relevant diagnostic tool for discriminating FLD patients from healthy exposed farmers (sensitivity 87 %, specificity 100 %). DD tests were in accordance with ES, but their discriminatory power was lower. No threshold indicating both good sensitivity and specificity could be established with ELISA. WB analysis failed to identify specific bands for FLD. This study demonstrates the efficacy of determining precipitin levels with an appropriate technique, using a panel of antigens consistent with the specific exposure of a given area.