Effects of pulmonary surfactant and surfactant protein A on phagocytosis of fractionated alveolar macrophages: relationship to starvation.
Pulmonary surfactant isolated from bronchoalveolar lavage fluid of rat lung contained a high content of surfactant protein A (SP-A) in starved for 2 days compared to fed controls, but this phenomena returned to baseline following more than 4 days starvation. As determined by immunoperoxidase staining of lung sections using SP-A antibody, SP-A could be consistently observed in nonciliated bronchiolar (Clara) cells, alveolar type II cells and some alveolar macrophages (AM). Fc receptor-mediated phagocytosis of AM was enhanced by SP-A, which was dependent on the dosis and reached a maximum at 10 micrograms of SP-A/ml. Antibody to SP-A completely inhibited the enhanced response of phagocytosis. When exposed AM subpopulations, separated into four fractions (I, II, III and IV) by discontinuous Percoll gradient, to SP-A or pulmonary surfactant prepared from rats fed and starved for 2 days enhanced their phagocytic activity in high dense cells (III and IV), particularly to SP-A and pulmonary surfactant from rats starved for 2 days. Whereas little change in lower dense fractions (I and II) were seen in all exposures except for SP-A that enhanced the cells of fraction II. These results supported the concept that pulmonary surfactant and its apoprotein, SP-A, are a factor to regulate lung defense system including activation of AM that undergo different processes following starvation.
Sakai
K
K
Department of Nutrition, School of Medicine, University of Tokushima, Japan.
Kweon
M N
MN
Kohri
T
T
Kishino
Y
Y
D000818:Animals; D000906:Antibodies / Q000276:immunology; D015153:Blotting, Western; D002478:Cells, Cultured; D007150:Immunohistochemistry; D008168:Lung / Q000276:immunology; D016676:Macrophages, Alveolar / Q000502:physiology*; D008297:Male; D010587:Phagocytosis / Q000502:physiology*; D011510:Proteolipids / Q000302:isolation & purification / Q000502:physiology*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000302:isolation & purification / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D011961:Receptors, Fc / Q000378:metabolism; D013217:Starvation; D013997:Time Factors
D000906:Antibodies; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D011961:Receptors, Fc