DIFFERENTIAL CELLULAR ANALYSIS OF BRONCHOALVEOLAR LAVAGE FLUID OBTAINED AT VARIOUS STAGES DURING THE DEVELOPMENT OF BLEOMYCIN-INDUCED PULMONARY FIBROSIS IN THE RAT

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Abstract
To analyze the cellular conponents of bronchoalveolar lavage fluid throughout the development of bleomycin-induced pulmonary fibrosis in the rat, animals were killed and lavaged at various times after the administration of a single intratracheal injection of bleomycin. A significant influx of inflammatory cells appear in the lavage fluid as early as day 1 after bleomycin treatment. Polymorphonuclear leukocytes are the 1st cells to appear and significant concentrations persist for as long as 1 mo. after bleomycin treatment. There is a very transient yet significant influx of eosinophils on day 7 after bleomycin treatment. Lymphocytes are present from 3 to 14 days after bleomycin treatment; > 97% are T-cells and < 3% are B-cells. There is a 1:1 ratio of W3/25+ cells (helper cell activity) to OX8+ cells (suppressor cell activity) comprising the lymphocyte population. The blood and lymphoid tissue of these animals contain a normal 2:1 ratio of these subsets. Specific T-cell populations are present in the air spaces of the lung in response to bleomycin-induced pulmonary fibrosis in this model.