Cell kinetics in the lung as a predictive tool in the assessment of fibrogenesis and tumorigenesis

Studies are reported of lung cell kinetics and the relationship between cell injury and repair in lungs after damage by inhaled toxic materials. Mice were treated with three cytostatic drugs: cyclophosphamide, busulfan, or 1,3-Bis540-2-chloroethyl)-1-nitrosourea (BCNU). The alveolar labeling index was measured following drug administration with a pulse of tritium-labeled thymidine and autoradiography. Results show that proliferation of type II alveolar cells was never a prominent feature. This is in contrast to animals treated with oleic acid in which there was an initial burst of type II cell proliferation. Studies with BHT suggest that cell hyperplasia is not a prerequisite for tumor promotion in mouse lung