[Study of cell populations of bronchoalveolar lavage fluid in patients with pneumonia due to Chlamydia psittaci and Mycoplasma pneumoniae].

We have performed bronchoalveolar lavage (BAL) examination in 27 cases; 5 with Chlamydial pneumonia, 7 with Mycoplasmal pneumonia and 15 in the control group (5 non-smokers, 10 smokers), and the following results were obtained. 1. In Chlamydial pneumonia and Mycoplasmal pneumonia, the cell population of alveolar macrophages in BALF decreased (p < 0.01) and that of lymphocytes increased compared with control group (p < 0.01). 2. In all cases of Mycoplasmal pneumonia without peripheral eosinophilia, the cell population of eosinophils in BALF increased compared with cases of Chlamydial pneumonia (p < 0.05). These results indicate that lymphocytes played the main role in the immune host defense in Chlamydial pneumonia, whereas infiltration of lymphocytes and eosinophils into the pneumonic lesion occurred in Mycoplasma pneumoniae infection.