Surfactant catabolism.

Alveolar pulmonary surfactant is a complex of macromolecular aggregates composed of phospholipids and surfactant proteins (SP) that is essential for maintenance of normal lung function. The importance of surfactant homeostasis is recognized in the patients and the animal models with pulmonary disease, although the mechanisms of surfactant homeostasis are not fully understood. In this review the author will discuss: (i) the mechanisms of the surfactant catabolism by macrophage and type II cells; and (ii) the important role of SP-D on ultrastructure of surfactant that affects uptake by type II cells.