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Peroxidase-induced enhancement of chemiluminescence by murine peritoneal macrophages
D L Lefkowitz1, S S Lefkowitz, J Mone
1Department of Biological Sciences, Texas Tech University, Lubbock 79409.
Abstract:
A number of substances have been shown to enhance the respiratory burst (RB) of macrophages. Many of these substances are not normally found in vivo. The present study suggests that a group of enzymes characterized as peroxidases have the ability to significantly enhance the RB and concomitant phagocytosis by murine peritoneal macrophages. Horseradish peroxidase (HRP), lactoperoxidase (LPO), and microperoxidase (MPO) can significantly augment these functions. Both resident and thioglycollate-induced macrophages exhibited enhanced chemiluminescence (CL) upon exposure to HRP, however, the effect was more pronounced with the latter. The increase in CL was correlated with an increase in production of superoxide, which was measured by reduction of cytochrome c. Horseradish peroxidase immobilized on an inert carrier, was capable of enhancing the RB suggesting that it does not have to enter the cell in order to function. Hemin, hematoheme and hematoporphyrin had little effect on macrophage stimulated CL. All of the peroxidases tested caused increased phagocytosis of opsonized zymosan. These studies indicate that peroxidases are capable of stimulating the RB, phagocytosis and possibly other macrophage functions.
Insights
Peroxidases like HRP, LPO, and MPO significantly enhance macrophage respiratory burst (RB) and phagocytosis. These enzymes, even when immobilized, boost macrophage functions, indicating their potential role in immune responses.
Area of Science:
- Immunology
- Enzymology
Background:
- Macrophages play a crucial role in innate immunity.
- The respiratory burst (RB) and phagocytosis are key macrophage functions.
- Exogenous substances can modulate macrophage activity, but many are not naturally occurring.
Purpose of the Study:
- To investigate the effect of peroxidases on macrophage respiratory burst (RB) and phagocytosis.
- To determine if peroxidases can enhance macrophage immune functions.
Main Methods:
- Murine peritoneal macrophages (resident and thioglycollate-induced) were exposed to various peroxidases (HRP, LPO, MPO).
- Respiratory burst was assessed by measuring chemiluminescence (CL) and superoxide production (cytochrome c reduction).
- Phagocytosis was evaluated using opsonized zymosan.
Main Results:
- Horseradish peroxidase (HRP), lactoperoxidase (LPO), and microperoxidase (MPO) significantly enhanced macrophage chemiluminescence (CL) and superoxide production.
- The enhancement of RB by HRP was more pronounced in thioglycollate-induced macrophages.
- Immobilized HRP also enhanced RB, suggesting extracellular activity.
- All tested peroxidases increased the phagocytosis of opsonized zymosan.
Conclusions:
- Peroxidases are potent stimulators of macrophage respiratory burst and phagocytosis.
- These enzymes can enhance key macrophage functions, potentially contributing to immune responses.
- Peroxidases may represent a novel class of compounds for modulating macrophage activity.