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Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes
12:50

Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes

Published on: August 9, 2011

Some macrophages kill Listeria monocytogenes while others do not

S D Fleming1, P A Campbell

  • 1Department of Medicine, National Jewish Medical and Research Center, Denver, Colorado, USA.

Immunological Reviews
|August 1, 1997
PubMed

Insights

Macrophages kill Listeria monocytogenes (L. monocytogenes) when they have intermediate intracellular iron and specific surface receptors. Cell-surface interleukin-10 (IL-10) prevents macrophages from killing L. monocytogenes.

Area of Science:

  • Immunology
  • Cell Biology
  • Microbiology

Background:

  • Macrophages are crucial immune cells responsible for eliminating pathogens.
  • The mechanisms governing macrophage bactericidal activity against intracellular bacteria like Listeria monocytogenes (L. monocytogenes) are not fully understood.
  • Variability in macrophage killing capacity suggests regulation by differentiation, microenvironment, or other factors.

Purpose of the Study:

  • To identify key characteristics distinguishing macrophages capable of killing L. monocytogenes from those that are not.
  • To elucidate the roles of intracellular iron, phagocytic receptors, and cell-surface interleukin-10 (IL-10) in macrophage bactericidal function.

Main Methods:

  • Comparative analysis of macrophages with varying capacities to eliminate L. monocytogenes.
  • Assessment of intracellular iron levels in listericidal versus non-listericidal macrophages.
  • Investigation of the influence of specific macrophage receptors on L. monocytogenes intracellular fate.
  • Evaluation of the impact of cell-surface IL-10 expression on macrophage bactericidal activity.

Main Results:

  • Macrophages require intermediate intracellular iron levels to effectively kill L. monocytogenes.
  • The specific receptor used for L. monocytogenes phagocytosis influences the bacterium's intracellular survival.
  • Macrophages expressing cell-surface IL-10 are unable to kill L. monocytogenes.

Conclusions:

  • Macrophage bactericidal activity against L. monocytogenes is modulated by intracellular iron availability.
  • Phagocytic receptor engagement plays a role in determining the outcome of L. monocytogenes infection within macrophages.
  • The presence of cell-surface IL-10 impairs the ability of macrophages to eliminate L. monocytogenes, highlighting its immunosuppressive role.

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