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Phagocytosis and intracellular killing of pathogenic yeasts by human monocytes and neutrophils
Abstract:
The kinetics of phagocytosis and killing of four fungal forms with varying virulence by two types of phagocytic cells was examined. Human monocytes ingested Saccharomyces cerevisiae, Candida tropicalis, and the blastospores of Candida albicans more rapidly than did human neutrophils. There was no difference in the rate of phagocytosis of C. albicans pseudohyphae by these two cell types. Intracellular killing of each of the four fungal forms was consistently and significantly more rapid by monocytes than by neutrophils. Neutrophils were unable to destroy ingested C. albicans pseudohyphae. These experiments suggest that the monocyte plays an important role in host defenses against fungal diseases and that the relative virulence of the pathogenic yeasts in human disease may be related to the ability of these organisms to survival after being ingested by circulating phagocytes.
Insights
Human monocytes are more effective than neutrophils at phagocytosing and killing pathogenic fungi. This suggests monocytes play a key role in fungal disease defense, with yeast survival linked to phagocyte resistance.
Area of Science:
- Immunology
- Mycology
- Cell Biology
Background:
- Phagocytic cells are crucial for host defense against fungal infections.
- Understanding the differential capabilities of various phagocytes against fungi is essential for developing effective treatments.
Purpose of the Study:
- To compare the phagocytosis and intracellular killing kinetics of human monocytes and neutrophils against different fungal forms.
- To investigate the relationship between fungal virulence and survival within phagocytic cells.
Main Methods:
- Comparative analysis of phagocytosis rates by monocytes and neutrophils.
- Assessment of intracellular fungal killing by both cell types.
- Utilized four fungal forms with varying virulence, including Saccharomyces cerevisiae and Candida albicans (blastospores and pseudohyphae).
Main Results:
- Monocytes exhibited higher phagocytosis rates for Saccharomyces cerevisiae, Candida tropicalis, and Candida albicans blastospores compared to neutrophils.
- Phagocytosis rates for Candida albicans pseudohyphae were similar between monocytes and neutrophils.
- Intracellular killing was significantly more rapid and effective in monocytes than in neutrophils.
- Neutrophils were incapable of destroying ingested Candida albicans pseudohyphae.
Conclusions:
- Monocytes play a critical role in host defense against fungal pathogens.
- The virulence of pathogenic yeasts may correlate with their ability to evade destruction by circulating phagocytes.
- Differential phagocyte function impacts the outcome of fungal infections.