Chrysotile-induced asbestosis: changes in the free cell population, pulmonary surfactant and whole lung tissue of rats.

Rats inhaling chrysotile asbestos contracted asbestosis and fibrosis of the lungs. Studies of biochemical and morphological changes (between normal and treated animals) show that chrysotile induces an increase in the lung free cell population and pulmonary surfactant levels. Lysosomal enzyme levels are elevated in both the whole lung and free cell population and there are considerable changes in macrophage morphology. It is suggested that the primary response of the lung to chrysotile is an increase in surfactant production coupled with an increase in free cell numbers, in order to prevent the cytotoxic effect of the dust.