Abstract
Clinical and histopathological findings were analyzed in 39 cases of hypersensitivity pneumonitis (HP). There were 21 cases of a pneumonitis referred to as “summer-type” in Japan, and 5 cases induced by isocyanate and other organic solvent, 2 cases of an air humidifier lung, one case in a pigeon breeder, one case induced by antioxidants and the cause in the other cases was unknown. The results of transbronchial lung biopsy and pulmonary function tests showed yielded typical findings. The lymphocyte count in bronchoalveolar lavage fluid (BALF) was 20% higher than normal in 25 of the 28 cases examined, and the higher counts predominanted in summer-type and isocyanate-induced HP. The CD4/CD8 ratio in BALF was significantly lower in the isocyanate-induced HP than in summer-type HP. These findings indicate that isocyanate itself has a continuous and direct effect on suppressor-type T lymphocytes.
