Augmentation of rat alveolar macrophage migration by surfactant protein.

Since the alveolar macrophage (AM) resides in an environment made unique by the presence of pulmonary surfactant, we studied the effect of constituents of pulmonary surfactant on the migration of these cells in vitro. Whole pulmonary surfactant, surfactant phospholipids, and a delipidated preparation of surfactant consisting mainly of protein were tested for their effect on AM migration. Migration was measured in multiwell chemotaxis chambers with endotoxin-activated rat serum (EARS) as the stimulus. The delipidated surfactant material (DSM) markedly augmented the migration of rat AM. Enhancement was seen only when migration was stimulated with EARS. Augmentation of stimulated migration occurred over a wide range of protein concentrations in DSM (3.5 to 56 ¼g/ml) in a dose-dependent fashion. Rat AM that were preincubated with DSM and then tested in the Chemotaxis assay without DSM showed increased migration towards EARS when compared with AM preincubated in buffer alone. The enhancing effect of DSM on AM ...