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Streptococcal products and leukocyte activities
M Lambot1, J J Letesson, N Lostrie
1Department of Immunology, Facultés Notre Dame de la Paix, Namur, Belgium.
Abstract:
Various streptococcal species are directly responsible for udder infections which should normally be countered by polymorphonuclear neutrophils (PMNs). In order to detect a putative inhibition of streptococcal products on the activities of bovine PMNs, we used a combination of four tests which permits an adequate evaluation of PMNs functions, e.g. PMN adherence on endothelial cells, chemotactic assay, phagocytosis of bacteria labelled with fluorescein isothiocyanate (FITC) and measurement of anion superoxide production. The conclusion is that neither of the two pathogenic streptococcal species isolated from mastitis appeared to produce in vitro factors affecting PMN activities.
Insights
Bovine mastitis is often caused by streptococci. This study found that common mastitis-causing streptococcal species do not inhibit the function of bovine polymorphonuclear neutrophils (PMNs), which are crucial for fighting infection.
Area of Science:
- Veterinary immunology
- Bovine infectious diseases
- Microbial pathogenesis
Background:
- Udder infections in cattle, particularly mastitis, are frequently caused by streptococcal species.
- Polymorphonuclear neutrophils (PMNs) are critical immune cells responsible for combating bacterial infections in the mammary gland.
- Understanding the interaction between streptococci and bovine PMNs is essential for managing mastitis.
Purpose of the Study:
- To investigate whether streptococcal species isolated from bovine mastitis produce factors that inhibit the function of bovine polymorphonuclear neutrophils (PMNs).
- To evaluate the impact of streptococcal products on key PMN activities, including adherence, chemotaxis, phagocytosis, and superoxide anion production.
Main Methods:
- Utilized a combination of four assays to comprehensively assess bovine PMN functions.
- Assayed PMN adherence to endothelial cells.
- Conducted chemotactic assays to measure PMN migration.
- Quantified phagocytosis of fluorescein isothiocyanate (FITC)-labeled streptococci.
- Measured superoxide anion production by PMNs.
Main Results:
- In vitro testing revealed no significant inhibition of bovine PMN activities by the tested streptococcal species.
- Streptococcal products did not impair PMN adherence, chemotaxis, phagocytosis, or superoxide production.
- The two pathogenic streptococcal species isolated from mastitis cases did not demonstrate inhibitory effects on PMN functions.
Conclusions:
- The pathogenic streptococcal species commonly associated with bovine mastitis do not appear to produce factors that inhibit bovine PMN functions in vitro.
- Bovine PMNs retain their functional capacity against these streptococci under the tested conditions.
- Further research may be needed to explore other mechanisms of streptococcal virulence or host-pathogen interactions in bovine mastitis.