Phagocytic activity of the alveolar epithelial cells in pulmonary asbestosis

In the course of pulmonary asbestosis in hamsters, alveolar epithelial cells can transform into large phagocytic cells which ingest asbestos fibers and produce asbestos bodies. In the process, the epithelial cells frequently lose their original Type I or Type II cell structure and change into a form intermediate between the epithelial cell and the alveolar macrophage. This transformation may be the result of continuous stimulation of the cells by repeated phagocytosis of asbestos, followed by rapid death of the host cell, release of the fibers and rephagocytosis by a new cell. It is suggested that some of the large macrophages in the alveolar spaces originate from the alveolar epithelial cells via the intermediate form.