ObjectiveTo observe the effects of porcine pulmonary surfactant(PPS) on the function of pulmonary alveolar macrophages(AMs) in vitro, so as to explore the mechanism by which PPS treating pulmonary contusion in rats. MethodsAMs were separated by adherent culture from bronchoalveolar lavage fluid of rats with pulmonary contusion. The AMs were then cultured with media containing PPS (100 μg/ml or 200 μg/ml), LPS (20 μg/ml)+PPS (100 μg/ml or 200 μg/ml), or LPS (20 μg/ml) alone for 2 h. Then the phagocytic function of AMs in each group was examined with fungus. TNF-α mRNA was determined by RT-PCR in AMs of each group. AMs untreated with PPS and LPS were taken as blank control. ResultsThe phagocytic function of the AMs and the expression of TNF-α mRNA were not significantly affected by PPS alone compared with the control group. LPS stimulation increased the phagocytic function of AMs and the TNF-α mRNA expression in AMs. PPS showed no significant effect on LPS-induced increase of phagocytic function of AMs, but it could greatly inhibit LPS-induced TNF-α mRNA increase. ConclusionPPS has no noticeable effect on the phagocytic function of the AMs, but it can inhibit TNF-α mRNA expression induced by LPS in AMs.