Characteristics of primary isolates of alveolar type II cells from neonatal rats.

Alveolar type II cells from 6-day-old rat pups were obtained at approximately 90% purity, as judged by light and electron microscopy. Within 48-72 h in culture, the cells formed a monolayer with tight junctions typical of epithelial cells. Type II cells aggregated into raised domelike areas, which when sectioned showed alveolarlike structures comprised of type II cells. After 3 days in culture these structures showed abundant lamellar body secretion. Phospholipid profiles were characteristic of type II cells, with disaturated phosphatidylcholine (DSPC) the predominant secreted phospholipid. The cells also released DSPC in response to beta-adrenergic stimulation. This release was inhibited by the specific beta-antagonist propranolol. The results show that morphologic differentiation and biochemical properties of neonatal type II cells can be studied using an isolated cell system in tissue culture.