[Pathogenesis and treatment of hypersensitivity pneumonitis]

Hypersensitivity pneumonitis (HP) is a granulomatous interstitial lung disease resulting from an immunologic reaction to the repeated inhalation of organic dusts and active chemicals. There are 50 or more groups of HP, but the prevalence varies from country to country, and even within a country, depending on a variety of occupational or environmental inhalants. In Western coutries farmer's lung, bird fancier's disease, humidifier lung, and air-conditioner disease are common, but in Japan summer-type HP is the most prevalent group. Summer-type HP is a house-related illnes induced by Trichosporon asahii and Trichosporon mucoides which contaminate the patients' home environments in hot and humid conditions. The polysaccharide antigen contains mannan backbone attached with short side chains consi-sting of mannose, xylose, and glucuronic acid residues. Both immune complex-mediated and T cell-mediated immune responses to the yeast are involved in the induction and development of the disease. Host factors such as HLA-DQw3 and cigarette smoking also play an important role in the develop-ment or suppression of the disease. An assay for serum anti-Trichosporon antibody by a Triko Kit is very useful for the serodiagnosis, and sanitization by cleaning, disinfecting, and removing from the colonizing location of Trichosporon prevents recurrence of the disease. Summer-type HP induced by Trichosporon is a new type of HP. It can be found in other countries including most Western countries, because Trichosporon asahii and Trichosporon mucoides distribute in the temperate and subtropical areas of the world.