[T-cell subpopulation of bronchoalveolar lavage fluid in patients of sarcoidosis and hypersensitivity pneumonitis--2 cases report].

Diffuse interstitial lung diseases include more than 100 varieties. Even for a chest specialist differential diagnosis is difficult; accurate diagnosis without transbronchial lung biopsy or open lung biopsy was particularly hard. Bronchoalveolar Lavage (BAL) is a new diagnostic procedure which is relatively safe and repeatable. It takes about 30 minutes more, during the usual bronchoscopic examination, to obtain fluid and cells from the lower respiratory tract. These specimens aid differential diagnosis and an understanding of pathogenesis in the early stage of diffuse interstitial lung disease. Two cases are reported. One was sarcoidosis, as proved by mediastinoscopic lymph node biopsy; the other one was hypersensitivity pneumonitis by clinical impression. Both patients received bronchoscopic examination with bronchoalveolar lavage. The bronchoalveolar lavage fluid showed an increase in total cell count, lymphocyte count and lymphocyte percentage. In sarcoidosis, the main T-lymphocyte subpopulation was helper T-lymphocytes while, in hypersensitivity pneumonitis, the main T-lymphocyte subpopulation was suppressor T-lymphocytes. We concluded that, if the patients of diffuse interstitial lung diseases had increased lymphocyte count and percentage in bronchoalveolar Lavage fluid, examination of the lymphocyte subpopulation would help differential diagnosis.