The type II epithelial cells of the lung. IV. Adaption and behavior of isolated type II cells in culture.

Type II lung epithelial cells were isolated from rabbit lungs using the method of Kikkawa and Yoneda (Kikkawa Y, Yoneda K: Lab Invest 30: 76, 1974). Successful primary cultures were obtained only after utilizing high density cell plating (greater than 3 X 10(5) viable cells per sq. cm.) and allowing an attachment time of 48 hours. Attachment efficiency of the isolated cell preparations was highest when medium was supplemented with 10% fetal calf serum. These conditions enabled us to obtain consistently successful primary type II lung cell cultures. Cultures were monitored for a period of 2 weeks after initiation. Light, phase, and electron microscopy examination demonstrated that these primary cultures were indeed type II cells. The principal morphologic feature was the presence of dense lamellar granules in these cells. These primary cultures retained the characteristic type II features for 3 to 5 days in vitro, after which cultures exhibited a progressive deterioration and loss of their phenotypic properties. This behavioral pattern of type II cells in culture may represent both accelerated proliferation and accelerated transformation of these cells into type I epithelial cells.