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Listeria species escape from the phagosomes of interleukin‐4‐deactivated human macrophages independent of listeriolysin
Author(s) -
Neumann Katja,
Eppler Elisabeth,
Filgueira Luis,
Groscurth Peter,
Gasal Eduard,
Schaffner Andreas,
Schoedon Gabriele,
Schneemann Markus
Publication year - 2003
Publication title -
immunology and cell biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0818-9641
DOI - 10.1046/j.1440-1711.2003.01196.x
Subject(s) - listeriolysin o , phagosome , listeria monocytogenes , microbiology and biotechnology , listeria , phagocytosis , macrophage , biology , phagolysosome , virulence , bacteria , in vitro , biochemistry , gene , genetics
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.