Chemotactic and chemokinetic activity of Streptococcus faecalis culture supernatant for equine neutrophils.

This study explores how the culture supernatant of Streptococcus faecalis, a type of bacteria, stimulates the movement of horse neutrophils (a type of white blood cell) in a lab setting, suggesting that bacteria produce substances aside from formylmethionyl peptides that equine neutrophils can recognize.

Objective of the Research

• The research was conducted to determine how Streptococcus faecalis culture supernatant (the medium in which bacteria grow) influences the activity of equine neutrophils, a type of white blood cell found in horses. Specifically, it aimed to evaluate the motility, or movement, of these cells towards the culture supernatant.

Methodology & Key Findings

• The study employed an under-agarose assay to measure the in vitro (or in a controlled lab environment) stimulation of equine neutrophils’ motility.
• The researchers observed that there was a significant increase in the migration of the neutrophils towards the culture supernatant, and this response increased in a sigmoidal (S-shaped) manner with the logarithmic concentration of the supernatant.
• Moreover, the paper posits that the streptococcal culture supernatant acted as both chemotactic and chemokinetic. Chemotactic refers to the movement of organisms or cells in response to chemical stimuli, while chemokinetic refers to the increase of random movement of cells due to chemical stimulation.
• The study confirmed that the culture fluid had a chemotactic effect because the neutrophils moved further towards the supernatant than can be explained by its chemokinetic effect.
• The chemotactic activity was also demonstrated by the changes in the orientation of the migrating cells during incubation.

Conclusion

• The results suggest that bacteria produce other cytotaxins (toxic substances harmful to cells) than formylmethionyl peptides, which may be recognized by horse neutrophils. Such evidence implies that bacterial infections could, in part, be identified and responded to by equine neutrophils via these cytotaxins.