Listeria species escape from the phagosomes of interleukin-4-deactivated human macrophages independent of listeriolysin

Immunol Cell Biol. 2003 Dec;81(6):431-9. doi: 10.1046/j.1440-1711.2003.01196.x.

Abstract

Listeria monocytogenes is the causative agent of infections like sepsis and meningitis, especially in immunocompromised hosts. Human macrophages are able to phagocytose and digest L. monocytogenes but IL-4 prevents human macrophages from killing the bacteria, the mechanisms of which are unknown. In the present study, we examined various listeria species and strains including wild-type and deletion mutants in human macrophages pretreated with IL-4. To analyse the IL-4-mediated deactivation process, we combined quantitative infection assays with various morphologic methods. IL-4 facilitates survival and escape of the pathogenic L. monocytogenes wild-type strain 10403S from the macrophage phagosomes. In untreated macrophages, the isogenic listeriolysin deletion mutant strain DP-L2161 was killed and did not escape from the phagolysosomes. However, after macrophage deactivation with IL-4 DP-L2161 survived and escaped from the phagosomes. This was also the case, but to a lesser extent, even for the naturally avirulent L. innocua. As detected by confocal laser-scanning fluorescence microscopy and electron microscopy, IL-4 permitted the escape of all listeria species tested, including DP-L2161 and L. innocua from the phagosomal compartment of the macrophages. We conclude that escape from the phagosome and survival of the listeria species tested in IL-4-deactivated human macrophages is independent of the virulence factor listeriolysin.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Toxins* / genetics
  • Cell Survival
  • Cells, Cultured
  • Heat-Shock Proteins* / genetics
  • Hemolysin Proteins* / genetics
  • Humans
  • Interleukin-4 / pharmacology*
  • Listeria monocytogenes / genetics
  • Listeria monocytogenes / immunology*
  • Listeria monocytogenes / pathogenicity
  • Macrophages / drug effects
  • Macrophages / immunology*
  • Macrophages / microbiology*
  • Microscopy, Electron, Transmission
  • Phagosomes / immunology*
  • Phagosomes / microbiology
  • Virulence

Substances

  • Anti-Bacterial Agents
  • Bacterial Toxins
  • Heat-Shock Proteins
  • Hemolysin Proteins
  • Interleukin-4
  • hlyA protein, Listeria monocytogenes