Killing of Klebsiella Pneumoniae by Human Alveolar Macrophages

Am J Physiol Lung Cell Mol Physiol. 2002 May;282(5):L944-56. doi: 10.1152/ajplung.00216.2001.

Abstract

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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bronchoalveolar Lavage Fluid / cytology
  • Bronchoalveolar Lavage Fluid / immunology
  • Calcium / metabolism
  • Carrier Proteins / metabolism
  • Collectins
  • Flow Cytometry
  • Humans
  • Immunity, Innate / immunology
  • Klebsiella Infections / immunology*
  • Klebsiella pneumoniae*
  • Lung Transplantation / immunology
  • Macrophages, Alveolar / immunology*
  • Macrophages, Alveolar / metabolism
  • Macrophages, Alveolar / microbiology*
  • Nitric Oxide / biosynthesis
  • Nitric Oxide / metabolism
  • Peroxynitrous Acid / metabolism
  • Phagosomes / immunology
  • Phagosomes / metabolism
  • Proteolipids / immunology
  • Proteolipids / metabolism
  • Pulmonary Surfactant-Associated Protein A
  • Pulmonary Surfactant-Associated Proteins
  • Pulmonary Surfactants / immunology
  • Pulmonary Surfactants / metabolism

Substances

  • Carrier Proteins
  • Collectins
  • Proteolipids
  • Pulmonary Surfactant-Associated Protein A
  • Pulmonary Surfactant-Associated Proteins
  • Pulmonary Surfactants
  • Peroxynitrous Acid
  • Nitric Oxide
  • Calcium