Lamellar bodies isolated from adult human lung tissue.

Lamellar bodies, the intracellular storage form of pulmonary surfactant, were isolated from adult human lung tissue. As shown by electron microscopy, the isolated human lamellar bodies resembled the lamellar bodies isolated from experimental animals. Chemical analysis revealed that the lamellar bodies consisted largely of lipids, particularly phospholipids (85%). The major phospholipid was phosphatidylcholine, which accounted for 71% of the total phospholipids. Phosphatidylglycerol and phosphatidylethanolamine were 10 and 8%, respectively, of the lamellar body phospholipid. Phosphatidylserine, phosphatidylinositol, lysophosphatidylcholine, and sphingomyelin were minor components. Cholesterol was found to represent 60% of the neutral lipids or 9% of the total lipids. Phosphatidylcholine contained largely saturated fatty acids, of which palmitic acid was the most abundant. Disaturated phosphatidylcholines comprised 67% of the total phosphatidylcholines. Phosphatidylglycerol and phosphatidylethanolamine contained considerably less saturated fatty acids. Only 24% of phosphatidylglycerol was disaturated. The chemical composition of adult human lamellar bodies was very similar to that of lamellar bodies derived from experimental animals. The similarities in morphology and chemical composition of lamellar bodies suggest that surfactant metabolism in human lung may be similar to that of other mammals.