Studies on the pathogenesis of hypersensitivity pneumonitis Part 1. Immunological and pathological examination of experimental animal model of hypersensitivity pneumonitis

Hypersensitivity pneumonitis is well known as an allergic respiratory disease although the exact pathogenesis is still in controversy. An experimental animal model was established with Micropolyspora faeni (Mf) as the antigen, and the various immunological mechanisms were evaluated. Transtracheal challange of Mf antigen in guinea pigs sensitized with Mf antigen showed granulomatous pneumonitis compatible with hypersensitivity pneumonitis in humans including the precipitating antibody. The cellular responses in the lungs of animal model was examined with bronchoalveolar lavage (BAL) and the increase of total cell count and lymphocyte percentage were shown to correlate with the degree of alveolitis. Lymphocytes in BAL fluid of sensitized guinea pigs were shown to repond to Mf antigen specifically. Several characteristics of hypersensitivity pneumonitis were clearly shown in this animal model. Although the actual pathogenesis in humans is still obscure. this model could be useful in the evaluation of the patients with hypersensitivity pneumonitis