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Fate of Listeria monocytogenes in murine peritoneal macrophage subpopulations
Abstract:
Peritoneal macrophages derived from CD-1 and C57BL/6 mice were separated into distinct groups based on their buoyant densities on discontinuous gradients of Percoll and assayed for antibacterial activity against Listeria monocytogenes. Subpopulations of peritoneal macrophages derived from Listeria-immune mice present a wide variation in their ability to control intracellular infection. Distinct subsets were found which exhibited bacteriostatic and listericidal activity. The fractionation procedure yielded a population of peroxidase-positive macrophages which were devoid of antilisterial action. Subpopulations of resident and elicited macrophages were also functionally heterogeneous in their ability to restrict intracellular growth of bacterial. In some experiments, subclasses were examined for secretion of plasminogen activator and phagocytosis of latex particles. These activities varied considerably with the status of activation of the macrophages, but failed to correlate with antimicrobial activity within given subpopulations.
Insights
This study reveals that peritoneal macrophage subpopulations from immune mice have varying abilities to fight Listeria monocytogenes infection. Some macrophages inhibit bacterial growth, while others are ineffective, highlighting functional heterogeneity in macrophage antimicrobial activity.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Peritoneal macrophages play a crucial role in host defense against bacterial infections.
- Immune responses involve complex cellular interactions and functional specialization within macrophage populations.
Purpose of the Study:
- To investigate the functional heterogeneity of peritoneal macrophage subpopulations against Listeria monocytogenes.
- To determine if distinct macrophage subsets exhibit varying levels of bacteriostatic and listericidal activity.
Main Methods:
- Macrophages from CD-1 and C57BL/6 mice were separated by buoyant density using Percoll gradients.
- Antibacterial activity against Listeria monocytogenes was assayed in distinct macrophage subpopulations.
- Plasminogen activator secretion and latex particle phagocytosis were assessed in some macrophage subclasses.
Main Results:
- Macrophage subpopulations from Listeria-immune mice displayed a wide range of intracellular infection control.
- Distinct subsets showed either bacteriostatic (inhibiting growth) or listericidal (killing bacteria) activity.
- Peroxidase-positive macrophages were found to lack antilisterial action.
- Functional heterogeneity was observed in both resident and elicited macrophage subpopulations regarding bacterial growth restriction.
Conclusions:
- Peritoneal macrophages are functionally heterogeneous, with distinct subpopulations possessing varying antimicrobial capacities against Listeria monocytogenes.
- Macrophage activation status influences functions like plasminogen activator secretion and phagocytosis, but these do not directly correlate with antimicrobial activity within specific subpopulations.