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Inhibition of adherence of Giardia intestinalis by human neutrophils and monocytes
A A Crouch1, W K Seow, L M Whitman
1Department of Child Health, University of Queensland, Mater Children's Hospital, South Brisbane, Australia.
Abstract:
Human neutrophils and monocytes were found to be capable of interfering with the in vitro adherence of Giardia intestinalis. Significantly greater inhibition of adherence was shown by stimulated phagocytic cells than by unstimulated cells. Both azurophil and specific granules extracted from the cytoplasm of neutrophils were equally potent in their adherence inhibitory activity. Dose-dependent effects on adherence were observed with granular enzymes and reactive oxygen species. Lower concentrations of reactive oxygen species were required for adherence inhibition that for growth inhibition. These results suggest that the adherence mechanism of G. intestinalis may be a feasible target for immunological attack by phagocytic cells.
Insights
Human phagocytic cells, like neutrophils and monocytes, can block Giardia intestinalis adherence. Stimulated cells and their granular components, including reactive oxygen species, show potent inhibitory effects, suggesting a target for immune attack.
Area of Science:
- Immunology
- Infectious Diseases
- Cell Biology
Background:
- Giardia intestinalis is a protozoan parasite that causes significant gastrointestinal infections worldwide.
- The adherence of G. intestinalis to the host intestinal epithelium is crucial for colonization and pathogenesis.
- Phagocytic cells, including neutrophils and monocytes, play a key role in the innate immune response against pathogens.
Purpose of the Study:
- To investigate the role of human neutrophils and monocytes in inhibiting the in vitro adherence of Giardia intestinalis.
- To determine the specific components within phagocytic cells responsible for adherence inhibition.
- To explore the potential of G. intestinalis adherence as a target for host immune responses.
Main Methods:
- In vitro assays measuring the adherence of G. intestinalis to host cells.
- Use of human neutrophils and monocytes (stimulated and unstimulated).
- Analysis of adherence inhibitory activity of neutrophil granules and their components (enzymes, reactive oxygen species).
Main Results:
- Human neutrophils and monocytes significantly inhibited G. intestinalis adherence in vitro.
- Stimulated phagocytic cells demonstrated greater adherence inhibition compared to unstimulated cells.
- Both azurophil and specific neutrophil granules were equally effective in inhibiting adherence.
- Granular enzymes and reactive oxygen species exhibited dose-dependent inhibition of adherence, with lower concentrations needed for adherence inhibition than for growth inhibition.
Conclusions:
- Human phagocytic cells possess mechanisms to interfere with Giardia intestinalis adherence.
- Neutrophil granules and their components, particularly reactive oxygen species, are key mediators of this inhibitory effect.
- The adherence mechanism of G. intestinalis represents a potential target for immunological attack by phagocytic cells, offering insights into host defense strategies.