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Dose-dependent macrophage stimulation by Corynebacterium parvum
L D Loose1, C L Astry, R Megirian
1Institute of Comparative and Human Toxicology, Albany Medical College, New York 12208.
Abstract:
Corynebacterium parvum (C. parvum) administered at a dose of either 0.1, 1 or 10 mg/kg intraperitoneally (ip) to BDF1 mice was evaluated for its influence on peritoneal exudate cell differentials, numbers, respiration, phagocytic activity and capacity and intracellular microbicidal activity. The ip administration of 1 mg/kg of C. parvum resulted in a 2-3 fold increase in the yield of peritoneal exudate cells 1-5 days after injection; 0.1 mg/kg was ineffective, while 10 mg/kg of C. parvum manifested an increased cell yield on days 1 and 5 following injection. No alterations in cell differentials were noted at any dose level. A trend toward a dose-related alteration in the respiratory burst, phagocytic activity and capacity was demonstrated. The most dramatic alteration observed was a profound increase in intracellular microbicidal activity in macrophages obtained from mice administered 1 mg/kg of C. parvum. The higher dose of C. parvum was suppressive. It was concluded that a relationship between macrophage microbicidal activity and tumor cell killing exists because the 1 mg/kg, which elicited maximal macrophage microbicidal activity, also induced the greatest increase in protection against two unrelated tumor models as previously reported.
Insights
Corynebacterium parvum (C. parvum) at 1 mg/kg significantly boosted macrophage microbicidal activity in mice. This dose also provided the greatest protection against tumor models, suggesting a link between macrophage function and anti-tumor effects.
Area of Science:
- Immunology
- Oncology
- Microbiology
Background:
- Corynebacterium parvum (C. parvum) is an immunomodulator with potential anti-tumor applications.
- Understanding the dose-dependent effects of C. parvum on macrophage function is crucial for optimizing its therapeutic use.
Purpose of the Study:
- To investigate the impact of varying doses of C. parvum on murine peritoneal exudate cells.
- To assess C. parvum's influence on macrophage activity, including respiration, phagocytosis, and intracellular microbicidal capacity.
- To explore the relationship between macrophage microbicidal activity and anti-tumor protection.
Main Methods:
- BDF1 mice were administered C. parvum intraperitoneally at doses of 0.1, 1, or 10 mg/kg.
- Peritoneal exudate cells were analyzed for differentials, numbers, respiration, phagocytic activity, and intracellular microbicidal activity.
- Macrophage activity was correlated with previously reported tumor protection data.
Main Results:
- A dose of 1 mg/kg C. parvum increased peritoneal exudate cell yield 2-3 fold, while 0.1 mg/kg was ineffective and 10 mg/kg showed a lesser increase.
- No significant alterations in cell differentials were observed across dose groups.
- A dose-related trend in respiratory burst and phagocytic activity was noted.
- The 1 mg/kg dose induced a profound increase in macrophage intracellular microbicidal activity.
- The higher dose (10 mg/kg) exhibited suppressive effects.
Conclusions:
- A specific dose (1 mg/kg) of C. parvum maximally enhances macrophage microbicidal activity in mice.
- Enhanced macrophage microbicidal activity correlates with increased protection against unrelated tumor models.
- C. parvum's immunomodulatory effects, particularly on macrophage function, are dose-dependent and relevant for cancer immunotherapy.