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Role of mitogenicity in pathogenicity of mycoplasmas for murine hosts
Abstract:
The mitogenicity and pathogenicity of Mycoplasma pulmonis were compared in two rat strains. Both the mitogenic and the pathologic effects induced by M. pulmonis membranes were more severe in Lewis rats than in Hooded rats, and were dependent on the mitogen doses used. It was concluded that the severity of lung lesions induced by M. pulmonis membranes correlated with the degree of mitogenic responses of the different rat strains to this organism. The roles of T- and B-cell mitogens in induction of pneumonia were studied in Hooded rats treated intranasally with either the T-cell mitogen concanavalin A or with M. neurolyticum membranes which stimulate the B-cell populations, or with both concanavalin A and M. neurolyticum. Results clearly showed that the individual B- and T-cell mitogens affected the lungs of treated animals. Nevertheless, the mitogenic co-stimulation of both B and T lymphocytes in rat lungs was necessary to obtain maximal development of interstitial lymphocytic pneumonia.
Insights
Lewis rats showed more severe lung damage from Mycoplasma pulmonis than Hooded rats. Optimal pneumonia development required co-stimulation of both B- and T-cell mitogens in rat lungs.
Area of Science:
- Immunology
- Pathology
- Microbiology
Background:
- Mycoplasma pulmonis is a pathogen that can cause respiratory disease in rats.
- Rat strains exhibit varying susceptibility to M. pulmonis infections.
- Mitogens, substances that induce cell division, can modulate immune responses.
Purpose of the Study:
- To compare the mitogenicity and pathogenicity of Mycoplasma pulmonis in Lewis and Hooded rats.
- To investigate the roles of T-cell and B-cell mitogens in the induction of pneumonia.
- To determine the necessity of co-stimulation of both lymphocyte types for maximal pneumonia development.
Main Methods:
- Comparison of M. pulmonis membrane-induced mitogenic and pathologic effects in Lewis and Hooded rats.
- Intranasal administration of concanavalin A (T-cell mitogen) or M. neurolyticum membranes (B-cell mitogen) to Hooded rats.
- Intranasal co-administration of both mitogens to Hooded rats.
Main Results:
- Lewis rats exhibited more severe mitogenic and pathologic responses to M. pulmonis membranes compared to Hooded rats.
- Individual T-cell and B-cell mitogens independently affected rat lungs.
- Maximal interstitial lymphocytic pneumonia development necessitated co-stimulation of both B- and T-lymphocytes.
Conclusions:
- Severity of lung lesions correlates with the degree of mitogenic responses in different rat strains.
- Both B- and T-cell mitogens play roles in pneumonia induction.
- Co-stimulation of B- and T-lymphocytes is essential for maximal interstitial lymphocytic pneumonia.