The phospholipids of rabbit type II alveolar epithelial cells: comparison with lung lavage, lung tissue, alveolar macrophages, and a human alveolar tumor cell line.

The phospholipid composition of type II alveolar epithelial cells from the rabbit was compared with that of alveolar macrophages, lung lavage and lung tissue. In addition, the phospholipid composition of a human alveolar tumor cell line, which is morphologically similar to type II cells, was examined. Phosphatidylcholine accounted for 48% of the total phospholipid in the type II cells, 41% in the tumor cells, and 30% in the macrophages. Phosphatidylcholine was 51% disaturated in the type II cells, 54% in lung lavage, 39% in whole lung, 29% in lavaged lung and macrophages, and 16% in the tumor cells. Palmitic acid was the major fatty acid in phosphatidylcholine from all samples with the exception of the tumor cells in which almost half of the fatty acids were accounted for by oleic acid. The phospholipids of the type II cells were more similar to those of lung lavage, and thus surfactant, than to lung tissue and macrophages. This is consistent with their supposed role in surfactant production. The tumor cells, although morphologically similar to type II cells, were quite different with respect to phospholipid composition.