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Effect of infection with gonococci on myeloperoxidase activity of leucocytes
Abstract:
Lyosomal myeloperoxidase activity in human phagocytic leucocytes was stimulated by incubation with virulent (T1) and avirulent (T4) forms of Neisseria gonorrhoeae. The amount of activity, assayed by bacterial iodination (125-iodine) after 30 min. exposure to the pagocytes in the absence of serum, was about fifty times greater in cells infected with T4 strains. In the presence of heated human serum, or its IgG component, myeloperoxidase activity increased, but T1-Stimulated activity was significantly less than that of T4 and was not proportional to multiplicity of infection. From these results and from those of a previous study we conclude that T1 can stimulate leucocyte myeloperoxidase activity from an extracellular location, that for this activity a serum fraction is required, and that this may be a mechanism responsible for some of the killing of the membrane associated T1.
Insights
Virulent Neisseria gonorrhoeae (T1) stimulates phagocytic leucocyte myeloperoxidase activity extracellularly, requiring serum factors. Avirulent strains (T4) show higher activity, suggesting a mechanism for T1 bacterial killing.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Phagocytic leucocytes play a crucial role in the innate immune response against bacterial pathogens.
- Myeloperoxidase (MPO) is a key enzyme in phagocytes, involved in generating antimicrobial oxidants.
- Neisseria gonorrhoeae exhibits different virulence properties, impacting host-pathogen interactions.
Purpose of the Study:
- To investigate the effect of virulent (T1) and avirulent (T4) Neisseria gonorrhoeae strains on lysosomal myeloperoxidase (MPO) activity in human phagocytic leucocytes.
- To determine the role of serum components in modulating MPO activity upon N. gonorrhoeae infection.
Main Methods:
- Incubation of human phagocytic leucocytes with T1 and T4 N. gonorrhoeae strains.
- Assay of MPO activity using bacterial iodination with 125-iodine.
- Evaluation of MPO activity in the presence and absence of heated human serum or its IgG component.
Main Results:
- Incubation with N. gonorrhoeae stimulated lysosomal MPO activity in leucocytes.
- Avirulent T4 strains induced approximately 50-fold greater MPO activity compared to virulent T1 strains after 30 minutes in the absence of serum.
- In the presence of heated serum or IgG, MPO activity increased, but T1-stimulated activity remained significantly lower than T4-stimulated activity and was not proportional to the multiplicity of infection.
Conclusions:
- Virulent T1 N. gonorrhoeae can stimulate leucocyte MPO activity from an extracellular location.
- A serum fraction is required for this extracellular MPO stimulation by T1.
- This mechanism may contribute to the killing of membrane-associated virulent T1 strains.