Surfactant protein A mediates mycoplasmacidal activity of alveolar macrophages.
Mycoplasma pneumoniae is a leading cause of pneumonia and exacerbates other respiratory diseases in humans. We investigated the potential role of surfactant protein (SP) A in antimycoplasmal defense using alveolar macrophages (AMs) from C57BL/6NCr (C57BL) mice, which are highly resistant to infections of Mycoplasma pulmonis. C57BL AMs, activated with interferon (IFN)-gamma and incubated with SP-A (25 micrograms/ml) at 37 degrees C, produced significant amounts of nitric oxide (.NO; nitrate and nitrite production = 1.1 microM.h-1.10(5) AMs-1) and effected an 83% decrease in mycoplasma colony-forming units (CFUs) by 6 h postinfection. Preincubation of AMs with the inducible nitric oxide synthase inhibitor NG-monomethyl-L-arginine abolished .NO production and SP-A-mediated killing of mycoplasmas. No decrease in CFUs was seen when IFN-gamma-activated macrophages were infected with mycoplasmas in the absence of SP-A despite significant .NO production (nitrate and nitrite production = 0.6 microM.h-1.10(5) AMs-1). These results demonstrate that SP-A mediates killing of mycoplasmas by AMs, possibly through an .NO-dependent mechanism.
Hickman-Davis
J M
JM
Department of Comparative Medicine, School of Medicine, University of Alabama at Birmingham 35294, USA.
Lindsey
J R
JR
Zhu
S
S
Matalon
S
S
D000818:Animals; D006023:Glycoproteins / Q000502:physiology*; D006801:Humans; D016676:Macrophages, Alveolar / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008970:Molecular Weight; D009569:Nitric Oxide / Q000378:metabolism; D010587:Phagocytosis; D011019:Pneumonia, Mycoplasma / Q000276:immunology*; D011485:Protein Binding; D011510:Proteolipids / Q000502:physiology*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000502:physiology*
D006023:Glycoproteins; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D009569:Nitric Oxide