Pulmonary surfactant-associated protein A enhances the surface activity of lipid extract surfactant and reverses inhibition by blood proteins in vitro.

Although a monolayer of dipalmitoylphosphatidylcholine, the major component of pulmonary surfactant, is thought to be responsible for the reduction of the surface tension at the air-liquid interface of the alveolus, the participation of unsaturated and anionic phospholipids and the three surfactant-associated proteins is suggested in the generation and maintenance of this surface-active monolayer. We have examined the effects of …