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Respiratory diseases in cyclophosphamide-treated mice. I. Increased virulence of Mycoplasma pulmonis
Abstract:
Mice infected intranasally with Mycoplasma pulmonis were treated with cyclophosphamide, a potent immunologic suppressor. In place of a chronic smouldering infection with little mortality (2%), a rapidly lethal infection with high mortality (66%) was produced. M. pulmonis was able to be isolated from several organs during the course of the unmodified infection. In the infected animals treated with cyclophosphamide, dissemination occurred earlier, and higher titers of mycoplasma were found. Reconstitution experiments with spleen cells from previously infected animals reversed the effect of cyclophosphamide, indicating that immunity plays an important role in containment of the infection and eventual recovery.
Insights
Suppressing immunity with cyclophosphamide transformed a mild Mycoplasma pulmonis infection in mice into a lethal one. This highlights the critical role of the immune system in controlling bacterial infections and enabling recovery.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Mycoplasma pulmonis causes chronic respiratory infections in mice.
- The immune system is crucial for controlling Mycoplasma infections.
Purpose of the Study:
- To investigate the role of immunity in Mycoplasma pulmonis infection using an immunosuppression model.
- To determine the impact of cyclophosphamide on infection dynamics and mortality.
Main Methods:
- Mice were infected intranasally with Mycoplasma pulmonis.
- Mice were treated with cyclophosphamide, an immunosuppressive drug.
- Mycoplasma pulmonis dissemination and titers were monitored.
- Reconstitution experiments with spleen cells were performed.
Main Results:
- Cyclophosphamide treatment increased mortality from 2% to 66%.
- Immunosuppression led to earlier dissemination and higher Mycoplasma titers.
- Spleen cell reconstitution reversed the lethal effects of cyclophosphamide.
Conclusions:
- Immunity is essential for containing Mycoplasma pulmonis infection.
- Immunosuppression significantly exacerbates Mycoplasma pulmonis infections.
- Immune cells play a key role in recovery from Mycoplasma pulmonis.