[Lymphocyte populations in bronchoalveolar lavage fluid in various interstitial lung diseases].

Differential cell counts, T-, Tactive-, Tstable-, and B-lymphocytes were studied in bronchoalveolar lavage (BAL) fluid and in peripheral blood from patients with thoracic sarcoidosis (S), extrinsic allergic alveolitis (EAA) and idiopathic pulmonary fibrosis (IPF). In patients with S and EAA the total number of lymphocytes, the percentage of T-, Tactive-, and Tstable-lymphocytes were increased in BAL-fluid, especially in cases of active S and of acute EAA. Contrary to the BAL-fluid the peripheral blood values for T-lymphocytes were decreased in S and in the range of the control group (healthy volunteers) in EAA. The BAL-fluid of patients with IPF is characterized by a high number of polymorphonuclear cells, especially neutrophils. Current concepts of pathogenesis of interstitial lung diseases are discussed and the possible key role of alveolitis in this process is elucidated.