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Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes
Published on: August 9, 2011
Enhanced resistance to Listeria monocytogenes in splenectomized mice
Abstract:
Mice infected with live Listeria monocytogenes intravenously from 1 week to 3 months following splenectomy exhibit greatly enhanced antibacterial resistance to this micro-organism as compared to normal or sham-splenectomized mice. They survive a dose of Listeria 100 times higher than is the LD50 of this parasite for normal mice. Initially, the same number of viable micro-organisms lodge in the livers of splenectomized and normal hosts. However, within 24 h after infection, the number of viable Listeria which can be recovered from the livers of splenectomized animals is significantly reduced in comparison with control mice. This effect of splenectomy is transient and gradually disappears spontaneously within 3 months following splenectomy. Enhancement of anti-listerial resistance in splenectomized mice can be abrogated by the transfer of normal spleen cells. The presence of a normal splenic cell population that controls macrophage activation is postulated.
Insights
Splenectomy enhances antibacterial resistance in mice against Listeria monocytogenes. This heightened immunity is temporary and linked to spleen cell function, suggesting a role in macrophage activation.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- The spleen plays a crucial role in immune responses against systemic infections.
- Understanding the impact of splenectomy on host defense mechanisms is vital for clinical applications.
Purpose of the Study:
- To investigate the effect of splenectomy on antibacterial resistance to Listeria monocytogenes in mice.
- To determine the duration and mechanisms underlying splenectomy-induced immune enhancement.
Main Methods:
- Mice underwent splenectomy or sham surgery and were subsequently infected intravenously with Listeria monocytogenes.
- Bacterial load in the liver was quantified at various time points post-infection.
- Cell transfer experiments were conducted using normal spleen cells.
Main Results:
- Splenectomized mice demonstrated significantly enhanced resistance to Listeria monocytogenes, surviving 100-fold higher doses compared to controls.
- An initial reduction in viable Listeria was observed in splenectomized mice within 24 hours.
- This enhanced resistance was transient, diminishing within 3 months post-splenectomy, and could be reversed by transferring normal spleen cells.
Conclusions:
- Splenectomy confers a temporary but potent enhancement of antibacterial immunity against Listeria monocytogenes.
- The findings suggest that splenic cells, potentially those involved in macrophage activation, are critical for controlling Listeria infection.
- Further research into the specific splenic cell populations and their mechanisms is warranted.
