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Interactions between human granulocytes and Blastomyces dermatitidis.
Infection and Immunity
|January 1, 1979
Summary
Human granulocytes attract and engulf Blastomyces dermatitidis, but struggle to kill it effectively. This study reveals a potential resistance of B. dermatitidis to granulocyte-mediated killing mechanisms in vitro.
Area of Science:
- Immunology
- Mycology
- Infectious Diseases
Background:
- Granulocytes are key immune cells in host responses to systemic fungal infections.
- Blastomyces dermatitidis is a fungus causing blastomycosis, a systemic disease.
- Understanding granulocyte interactions with B. dermatitidis is crucial for host defense.
Purpose of the Study:
- To investigate in vitro interactions between human granulocytes and Blastomyces dermatitidis.
- To compare the chemotactic activity of B. dermatitidis with other fungi like Histoplasma capsulatum and Cryptococcus neoformans.
- To assess the phagocytic and fungicidal capabilities of granulocytes against B. dermatitidis.
Main Methods:
- Boyden chamber assays to measure granulocyte chemotaxis.
- Microscopy and electron microscopy to observe phagocytosis.
- Chemiluminescence assays to indicate granulocyte activation.
- Fungicidal assays to determine yeast killing by granulocytes.
Main Results:
- B. dermatitidis culture filtrates showed significantly higher granulocyte chemotactic activity compared to H. capsulatum and C. neoformans.
- Human granulocytes efficiently phagocytosed B. dermatitidis and showed brisk chemiluminescence.
- Granulocytes killed only 29% of B. dermatitidis inoculum within 3 hours, indicating limited fungicidal activity.
Conclusions:
- There is a notable discrepancy between the phagocytosis and intracellular killing of B. dermatitidis by human granulocytes.
- B. dermatitidis may possess resistance mechanisms against granulocyte microbicidal activities.
- Further research is needed to elucidate the mechanisms of B. dermatitidis resistance to host immune defenses.