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Fungicidal activity of rabbit alveolar and peritoneal macrophages against Candida albicans
Abstract:
We tested the ability of rabbit macrophages to kill Candida albicans in vitro. Resident (unstimulated) alveolar macrophages killed 28.1 +/- 1.9% of ingested organisms in 4 h, whereas resident peritoneal macrophages killed only 15.2 +/- 1.3% (mean +/- standard error of the mean, P < 0.01). Peritoneal macrophages obtained from rabbits treated 3 weeks earlier with complete Freund adjuvant showed enhanced candidacidal activity relative to normally resident peritoneal cells (28.2 +/- 3.1%, P < 0.01). Candidacidal activity by alveolar macrophages recovered from such treated animals was slightly enhanced relative to untreated alveolar macrophages (32.9 +/- 2.3%). Candidacidal activity by peritoneal and alveolar macrophages was not decreased by several agents (cyanide, azide, sulfadiazine, and phenylbutazone) that inhibit the ability of human blood monocytes to kill C. albicans. In contrast, candidacidal activity by alveolar macrophages was greatly diminished by iodoacetate, an ineffective inhibitor of this function in human monocytes. We conclude that rabbit macrophages kill C. albicans by a fungicidal mechanism distinct from the peroxidase-H2O2 mechanism of human granulocytes and monocytes, and that the fungicidal properties of peritoneal and alveolar macrophage populations are enhanced after nonspecific stimulation with complete Freund adjuvant.
Insights
Rabbit macrophages kill Candida albicans using a unique mechanism. Their fungicidal activity is enhanced by nonspecific stimulation with complete Freund adjuvant.
Area of Science:
- Immunology
- Microbiology
Background:
- Macrophages are key immune cells involved in pathogen clearance.
- Candida albicans is a common opportunistic fungal pathogen.
- Understanding macrophage fungicidal mechanisms is crucial for developing new antifungal strategies.
Purpose of the Study:
- To investigate the in vitro candidacidal activity of rabbit macrophages.
- To compare the fungicidal capabilities of alveolar and peritoneal macrophages.
- To elucidate the mechanism of C. albicans killing by rabbit macrophages and its distinction from human monocytes.
Main Methods:
- In vitro killing assays using rabbit alveolar and peritoneal macrophages.
- Assessment of candidacidal activity in resident and Freund adjuvant-stimulated macrophages.
- Evaluation of the effect of various inhibitory agents (cyanide, azide, sulfadiazine, phenylbutazone, iodoacetate) on macrophage fungicidal activity.
Main Results:
- Resident alveolar macrophages exhibited significantly higher candidacidal activity than resident peritoneal macrophages.
- Treatment with complete Freund adjuvant enhanced the candidacidal activity of both peritoneal and alveolar macrophages.
- Rabbit macrophage candidacidal activity was unaffected by agents inhibiting human monocyte killing but was sensitive to iodoacetate.
Conclusions:
- Rabbit macrophages employ a fungicidal mechanism distinct from the peroxidase-hydrogen peroxide system in human monocytes.
- Nonspecific stimulation with complete Freund adjuvant enhances the fungicidal properties of rabbit peritoneal and alveolar macrophages.
- These findings contribute to understanding host-pathogen interactions and developing novel therapeutic approaches against Candida albicans infections.