Toshio Ozaki

Characteristics of the cellular composition, especially the lymphocyte sub‐populations of bronchoalveolar lavage fluid from patients with summer‐type hypersensitivity pneumonitis

The pathogenesis of summer‐type hypersensitivity pneumonitis, which often occurs in Japan, was examined by analysing the cell profile, especially the lymphocyte sub‐populations, of bronchoalveolar lavage fluid from these patients: twenty‐two normal volunteers and fourteen patients with localized lung cancer as controls. Lymphocyte sub‐populations were determined by the micro‐testplate method. In the bronchial fluid of the summer hypersensitivity group, the total cell number was much higher (five to ten times) than in the control groups, and the percentage of lymphocytes reached 84‐2 + 5.1 (mean + s.e. mean); the percentage of T lymphocytes was significantly increased (95.6 + 1.0), but that of B lymphocytes (3.2 + 0.6) was similar to that of the control groups, though the absolute numbers of B and T lymphocytes were higher than in the control groups. In the peripheral blood of the summer hypersensitivity group, the percentage of B lymphocytes was significantly higher than that found in the normal volunteers, but that of T lymphocytes was not increased. Cellular changes in bronchial fluid were more evident than changes seen by X‐ray examination and are considered to be a good parameter of the severity of hypersensitivity pneumonitis. It is considered that cell‐mediated immunity as well as the Arthus reaction may be intimately related to the pathogenesis of summer‐type hypersensitivity pneumonitis.

Cytotoxic Factor for Fibroblasts in Bronchoalveolar Lavage Fluid of Bleomycin-Treated Rats

The mechanisms of lung injury and fibrosis in diffuse interstitial lung diseases were studied by tests on the in vitro effect of bronchoalveolar lavage fluid (BALF) from bleomycin-treated rats on quiescent fibroblasts in culture. The BALF was obtained on days 2, 3, 6, 15, and 29 after intratracheal administration of bleomycin. Cytotoxic activity was detected in the BALF only on day 2. The factor responsible for the cytotoxic activity was detected in 50-70% ammonium sulfate fraction, and lost 10% of its activity after 30 min at 56 degrees C, 75% after 10 min at 80 degrees C, and all activity after 10 min at 100 degrees C. The factor was completely precipitated by 60% acetone and was not extractable with ether. In ion exchange chromatography, the factor was eluted with the main fraction of protein, and gel filtration indicated that it had a molecular weight of 60-70 kDa. Histological examination showed disappearance of the normal alveolar architecture on day 2, and pulmonary fibrosis on day 15. Thus the cytotoxic factor may be one of factors responsible for lung injury and may act as trigger for subsequent fibrosis in bleomycin-induced lung damage.