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Stimulation of macrophages by cord factor and by heat-killed and living BCG
Abstract:
Trehalose-6,6'-dimycolate (cord factor; CF) injected into the peritoneal cavity of mice induced stimulation of the peritoneal macrophages, evidenced both by increased activity of the lysosomal enzyme, acid phosphatase, and by increased phagocytosis of Listeria monocytogenes. The increase in enzyme activity and phagocytosis was similar to that induced by killed or living BCG. When administered intravenously, CF or BCG did not induce stimulation of peritoneal macrophages. CF when added to tissue cultures of normal peritoneal cells did not induce increased acid phosphatase activity or increased phagocytosis of L. monocytogenes.
Insights
Trehalose-6,6'-dimycolate (cord factor) stimulates mouse peritoneal macrophages when injected into the abdominal cavity. This immune response, similar to BCG, enhances enzyme activity and phagocytosis, but not when administered intravenously or in tissue cultures.
Area of Science:
- Immunology
- Microbiology
- Biochemistry
Background:
- Trehalose-6,6'-dimycolate (cord factor) is a mycobacterial cell wall component.
- Cord factor's immunomodulatory effects require further investigation.
Purpose of the Study:
- To investigate the in vivo and in vitro immunomodulatory effects of cord factor on peritoneal macrophages.
- To compare the effects of cord factor with Bacillus Calmette-Guérin (BCG).
Main Methods:
- Intraperitoneal and intravenous administration of cord factor and BCG in mice.
- Assay of peritoneal macrophage acid phosphatase activity.
- Measurement of macrophage phagocytosis of Listeria monocytogenes.
- In vitro tissue culture experiments with peritoneal cells.
Main Results:
- Intraperitoneal injection of cord factor stimulated peritoneal macrophages, increasing acid phosphatase activity and phagocytosis of Listeria monocytogenes.
- These stimulatory effects were comparable to those induced by BCG.
- Intravenous administration of cord factor or BCG did not stimulate peritoneal macrophages.
- In vitro, cord factor did not enhance macrophage activity in tissue cultures.
Conclusions:
- Peritoneal macrophages are activated by intraperitoneal administration of cord factor in vivo.
- The route of administration is critical for cord factor's immunomodulatory effects.
- Cord factor's in vivo activation of macrophages may be relevant for understanding host-pathogen interactions in mycobacterial infections.