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Chemotactic activity of polymorphonuclear leukocytes to Streptococcus pyogenes
Abstract:
Influence of two different streptococcal group A type 12 strains on chemotactic activity of polymorphonuclear leukocytes (PMN) was investigated in vitro and in vivo. The strains differed only in presence of M protein. In both conditions, the inhibition of the chemotaxis of the PMN after their treatment with M positive strains was observed. These results suggest that M protein of streptococci inhibits chemotaxis of PMN and therefore they can weaken defensive mechanisms of infected organism.
Insights
Streptococcal M protein inhibits polymorphonuclear leukocyte (PMN) chemotaxis. This finding suggests M protein weakens the body's immune defenses against group A Streptococcus infections.
Area of Science:
- Immunology
- Microbiology
- Bacteriology
Background:
- Group A Streptococcus (GAS) is a significant human pathogen.
- The M protein is a key virulence factor in GAS.
- Polymorphonuclear leukocytes (PMNs) are crucial immune cells involved in bacterial clearance.
Purpose of the Study:
- To investigate the effect of GAS M protein on PMN chemotaxis.
- To compare the influence of M protein-positive and M protein-negative GAS strains on PMN function.
Main Methods:
- In vitro and in vivo experiments were conducted.
- Chemotactic activity of PMNs was assessed after exposure to different GAS strains.
- The presence or absence of M protein on the GAS strains was the primary variable.
Main Results:
- PMN chemotaxis was significantly inhibited when exposed to M protein-positive GAS strains.
- This inhibitory effect was observed in both in vitro and in vivo models.
- M protein-negative strains did not exhibit the same level of inhibition.
Conclusions:
- The M protein of group A Streptococcus directly inhibits PMN chemotaxis.
- This inhibition can impair the host's innate immune response.
- Targeting M protein function could be a strategy to enhance host defense against GAS infections.