The effects of levamisole on some functions of mouse macrophages after in vitro and in vivo administration
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Abstract:
In vitro incubation of peritoneal macrophages from normal, peptone-stimulated mice with levamisole (1-100 microM) for 1 and 22 h had no effect on either phagocytosis of particulate material (sheep erythrocytes, zymosan) or cellular levels and release of lysosomal enzymes (beta-D-glucuronidase, cathepsin D). By contrast, levamisole 1 and 5 mM dramatically increased enzyme release while inhibiting phagocytosis. In some experiments, however, these high concentrations of levamisole caused an elevated cell mortality. When incubation was extended to 72 h, a decrease of both phagocytosis and enzyme release was observed. The catabolism of endocytosed antigens (sheep erythrocytes, human gammaglobulin) was not at all or only slightly modified depending upon the antigen. The cellular level of cyclic AMP remained unchanged in all experiments. In vivo exposure of macrophages to levamisole (2.5 and 10 mg/kg/day i.p. for 3 days) produced a dose-dependent increase in processing of endocytosed antigens as shown by an enhanced transfer of initially endocytosed material to the macrophage plasma membrane. The other parameters were not modified. The immunogenicity of erythrocytes, when endocytosed by levamisole-treated macrophages and transferred into unsensitized recipients, was increased in some in vivo experiments.
Insights
Levamisole affects macrophage function differently in vitro and in vivo. While high concentrations inhibit phagocytosis in vitro, in vivo exposure enhances antigen processing and immunogenicity of macrophages.
Area of Science:
- Immunology
- Cell Biology
Background:
- Macrophages are crucial immune cells involved in phagocytosis and antigen presentation.
- Levamisole is an immunomodulatory drug with known effects on immune cells.
Purpose of the Study:
- To investigate the in vitro and in vivo effects of levamisole on macrophage functions.
- To assess levamisole's impact on phagocytosis, lysosomal enzyme release, antigen catabolism, and immunogenicity.
Main Methods:
- In vitro incubation of mouse peritoneal macrophages with varying levamisole concentrations.
- In vivo administration of levamisole to mice followed by macrophage analysis.
- Assays for phagocytosis, lysosomal enzyme activity, antigen processing, and cell viability.
Main Results:
- In vitro: Low levamisole concentrations had no effect; high concentrations (1-5 mM) inhibited phagocytosis and increased enzyme release, with some cytotoxicity.
- In vitro: Antigen catabolism and cyclic AMP levels were largely unaffected.
- In vivo: Levamisole (2.5-10 mg/kg/day) dose-dependently increased antigen processing and enhanced erythrocyte immunogenicity when presented by macrophages.
Conclusions:
- Levamisole exhibits concentration-dependent and context-specific effects on macrophage functions.
- In vivo administration of levamisole enhances macrophage antigen processing and presentation, potentially boosting immune responses.