Aspects of metabolism and storage of pulmonary surfactant: experiments with isolated type II pneumocytes and lamellar bodies.

This review briefly summarizes our knowledge of the composition of pulmonary surfactant and the mechanisms involved in its biosynthesis. The currently available evidence suggests that dipalmitoylphosphatidylcholine, the major surface-active component of surfactant, can be synthesized in the alveolar type II pneumocyte via two pathways: (1) by direct synthesis de novo via the CPDcholine route, and (2) by remodelling of unsaturated phosphatidylcholines, most likely via a deacylation-reacylation mechanism. In addition, this paper focusses on recent findings concerning the biochemical characterization of lamellar bodies, the intracellular storage organelles of surfactant. Lamellar bodies from adult human lung contain a lamellar body-specific alpha-glucosidase--which should prove useful as a specific marker enzyme for this organelle.