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Cocaine alters the respiratory burst and phagocytic activity of murine macrophages
A Vaz1, S S Lefkowitz, D L Lefkowitz
1Department of Medical Microbiology, Texas Tech University Health Sciences Center, Lubbock 79430.
Abstract:
The effects of cocaine on the respiratory burst (RB) and the phagocytic activity of murine macrophages (M phi) were studied. C57BL/6 mice were injected intraperitoneally with various concentrations of cocaine or appropriate vehicle. Peritoneal and alveolar M phi were isolated from mice and cultured in vitro. Both alveolar and peritoneal M phi from cocaine-exposed mice exhibited an increase in the RB when compared with M phi from saline-injected controls. This increase in the RB was apparent 60 min after injection and persisted for at least 48 hr. Injection of the cocaine metabolites, ecgonine methyl ester hydrochloride and ecgonine hydrochloride, did not affect the RB. The increase in the RB was correlated with an increase in phagocytosis of opsonized zymosan in vitro. However, an in vivo phagocytic assay using mice injected ip with cocaine, which was subsequently followed by sheep erythrocytes, demonstrated the opposite effect. Fewer peritoneal M phi from cocaine-injected mice were observed with ingested erythrocytes. These data underscore the complex effects of cocaine on M phi functions.
Insights
Cocaine exposure increases respiratory burst in mouse macrophages, enhancing their ability to engulf particles in vitro. However, in vivo, cocaine impairs macrophage phagocytosis of red blood cells, revealing complex immune effects.
Area of Science:
- Immunology
- Pharmacology
- Cell Biology
Background:
- Macrophages are critical immune cells involved in pathogen clearance.
- Cocaine is a stimulant drug with known physiological effects.
- The impact of cocaine on macrophage function, particularly the respiratory burst and phagocytosis, requires further investigation.
Purpose of the Study:
- To investigate the effects of cocaine on the respiratory burst (RB) and phagocytic activity of murine macrophages (M phi).
- To determine if cocaine metabolites influence these macrophage functions.
- To assess the in vitro and in vivo phagocytic capacity of macrophages following cocaine exposure.
Main Methods:
- C57BL/6 mice were injected intraperitoneally with varying cocaine concentrations or vehicle.
- Peritoneal and alveolar macrophages were isolated and cultured.
- Respiratory burst and phagocytosis assays (opsonized zymosan in vitro, sheep erythrocytes in vivo) were performed.
Main Results:
- Cocaine exposure significantly increased the respiratory burst in both peritoneal and alveolar macrophages for at least 48 hours.
- The increase in RB correlated with enhanced in vitro phagocytosis of opsonized zymosan.
- In vivo, cocaine-injected mice showed reduced phagocytosis of sheep erythrocytes by peritoneal macrophages.
Conclusions:
- Cocaine has complex and contrasting effects on macrophage functions.
- While enhancing RB and in vitro phagocytosis, cocaine impairs in vivo phagocytic clearance.
- Cocaine metabolites did not appear to affect the respiratory burst.