The effect of type 2 cell mitosis on the surfactant system of injured mouse lungs

This study was designed to evaluate the effect of type 2 cell proliferation, and specifically mitosis, on the surfactant system after lung injury. Lung injury was produced in mice with butylated hydroxytoluene (BHT). The LB volume density and the LB area of tritiated thymidine (3H-T) labeled and mitotic type 2 cells were determined by combining light microscopic autoradiography with electron microscopic morphometry. Over a 48-hr period, the LB volume density of proliferating (3H-T-labeled) type 2 cells decreased from 20.7% to 7.6% (p less than 0.001) and the LB area per cell decreased from 9.1 to 2.4 mumol2 (p less than 0.001). These changes were closely related to type 2 cell mitosis, since the LB volume density decreased from 19.2% to 2.9% (p less than 0.001) and the LB area per cell decreased from 9.1 to 1.7 mumol2 (p less than 0.01) between prophase and telophase, but they were independent of the time elapsed since injury. These results indicate that mitosis influenced the LB content of type 2 cells after lung injury and suggest a previously unrecognized link between cell division and the surfactant system of the lung.