Killing of Klebsiella pneumoniae by human alveolar macrophages.
We investigated putative mechanisms by which human surfactant protein A (SP-A) effects killing of Klebsiella pneumoniae by human alveolar macrophages (AMs) isolated from bronchoalveolar lavagates of patients with transplanted lungs. Coincubation of AMs with human SP-A (25 microg/ml) and Klebsiella resulted in a 68% decrease in total colony forming units by 120 min compared with AMs infected with Klebsiella in the absence of SP-A, and this SP-A-mediated effect was abolished by preincubation with N(G)-monomethyl-L-arginine. Incubation of transplant AMs with SP-A increased intracellular Ca(2+) concentration ([Ca(2+)](i)) by 70% and nitrite and nitrate (NO(x)) production by 45% (from 0.24 +/- 0.02 to 1.3 +/- 0.21 nmol small middle dot 10(6) AMs(-1).h(-1)). Preincubation with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester inhibited the increase in [Ca(2+)](i) and abrogated the SP-A-mediated Klebsiella phagocytosis and killing. In contrast, incubation of AMs from normal volunteers with SP-A decreased both [Ca(2+)](i) and NO(x) production and did not result in killing of Klebsiella. Significant killing of Klebsiella was also seen in a cell-free system by sustained production of peroxynitrite (>1 microM/min) at pH 5 but not at pH 7.4. These findings indicate that SP-A mediates pathogen killing by AMs from transplant lungs by stimulating phagocytosis and production of reactive oxygen-nitrogen intermediates.
Hickman-Davis
Judy M
JM
Department of Anesthesiology, Division of Nephrology and Nephrology Research Training Center, School of Medicine, University of Alabama at Birmingham, 35294, USA.
O'Reilly
Philip
P
Davis
Ian C
IC
Peti-Peterdi
Janos
J
Davis
Glenda
G
Young
K Randall
KR
Devlin
Robert B
RB
Matalon
Sadis
S
D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D037222:Collectins; D005434:Flow Cytometry; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology; D007710:Klebsiella Infections / Q000276:immunology*; D007711:Klebsiella pneumoniae; D016040:Lung Transplantation / Q000276:immunology; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000378:metabolism; D010588:Phagosomes / Q000276:immunology / Q000378:metabolism; D011510:Proteolipids / Q000276:immunology / Q000378:metabolism; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000276:immunology / Q000378:metabolism
D002352:Carrier Proteins; D037222:Collectins; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D002118:Calcium