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Effect of Rhodococcus equi on equine polymorphonuclear leukocyte function
Veterinary Immunology and Immunopathology
|October 1, 1984
Summary
Rhodococcus equi preparations suppressed equine polymorphonuclear leukocyte (PMN) oxidative metabolism and myeloperoxidase activity. These findings suggest R. equi may possess components inhibiting PMN function, aiding its survival.
Area of Science:
- Veterinary Immunology
- Equine Microbiology
- Leukocyte Biology
Background:
- Polymorphonuclear leukocytes (PMNs) are crucial for equine innate immunity.
- Understanding PMN function is vital for combating bacterial infections in horses.
- Rhodococcus equi is an important pathogen in foals.
Purpose of the Study:
- To develop a method for isolating equine PMNs.
- To evaluate the effect of R. equi on equine PMN function.
- To identify components of R. equi that may inhibit PMN activity.
Main Methods:
- Isolation of purified equine polymorphonuclear leukocytes (PMNs).
- Assessment of PMN function via Staphylococcus aureus ingestion, nitroblue tetrazolium reduction, and iodination assays.
- Exposure of PMNs to live, heat-killed R. equi, and its fractions (pellet, supernatant).
Main Results:
- Equine PMN S. aureus ingestion was unaffected by R. equi preparations.
- Nitroblue tetrazrazolium reduction and iodination assays showed suppressed PMN oxidative metabolism and myeloperoxidase activity, respectively.
- R. equi supernatant retained inhibitory effects after autoclaving and filtration, suggesting heat-stable inhibitory components.
Conclusions:
- Rhodococcus equi possesses components that inhibit key equine polymorphonuclear leukocyte functions, including oxidative metabolism and the myeloperoxidase-H2O2-halide system.
- These inhibitory mechanisms may contribute to the intracellular survival and virulence of R. equi in horses.
- Further research into these R. equi components could reveal novel therapeutic targets.