Pulmonary surfactant obtained from starved rats enhances phagocytosis of alveolar macrophages.

Phagocytic activity of alveolar macrophages (AM) was enhanced by pulmonary surfactant obtained from bronchoalveolar lavage fluid of rats starved for 2 days, as compared to fed. The enhanced activity of phagocytosis was dependent on the dose of surfactant. The prepared surfactant showed a different protein to phospholipid ratio of 0.108 in fed and 0.234 in 2 days starved, because of an increased ratio of protein in surfactant from 2 days starved rats. F(ab')2 anti-surfactant protein inhibited the enhanced AM phagocytosis by surfactant. These results suggested that the enhancement of AM phagocytosis in 2 days starved rats was on account of an increase of protein in their surfactant compared to fed.