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Measurement of NADPH oxidase activity in detergent lysates of human and mouse macrophage monolayers
Abstract:
An assay to measure NADPH oxidase activity in detergent lysates of macrophage monolayers is described. The addition of a reaction mixture containing appropriate concentrations of disrupting detergents, NADPH as oxidase substrate and cytochrome c as electron acceptor, to macrophages monolayers permits the reliable detection of a superoxide dismutase-sensitive NADPH-dependent cytochrome c reductive activity. This activity is strictly substrate dependent and NADH could not substitute for NADPH. The NADPH-dependent superoxide anion-forming activity (NADPH oxidase) was investigated in different populations of human and mouse macrophages. NADPH oxidase was activated by stimulation of macrophages with phorbol-myristate acetate and activity levels correlated with ability of intact cells to produce superoxide anion. The optimal conditions for assay of NADPH oxidase were investigated and the assay was used to measure the kinetic properties of the NADPH oxidase. The assay permits investigations of the enzymatic basis of oxidative metabolism in macrophages cultivated as adherent cells without any requirements for recovery of the cells in suspension and subcellular fractionation.
Insights
This study introduces a new assay to measure NADPH oxidase activity in macrophage cells. The assay reliably detects superoxide anion production, crucial for understanding oxidative metabolism in macrophages.
Area of Science:
- Biochemistry
- Cell Biology
- Immunology
Background:
- NADPH oxidase is a key enzyme in macrophage oxidative metabolism.
- Existing methods for measuring NADPH oxidase activity can be complex.
- Understanding macrophage oxidative function is critical in immunology.
Purpose of the Study:
- To develop and validate a novel assay for measuring NADPH oxidase activity in macrophage monolayers.
- To characterize the kinetic properties of NADPH oxidase.
- To enable the study of oxidative metabolism in adherent macrophages.
Main Methods:
- A new assay was developed using detergent lysates of macrophage monolayers.
- The assay measures NADPH-dependent cytochrome c reductive activity.
- Superoxide dismutase sensitivity was used to confirm activity.
Main Results:
- The assay reliably detects superoxide dismutase-sensitive NADPH oxidase activity.
- Activity was substrate-dependent, requiring NADPH specifically.
- Stimulation with phorbol-myristate acetate activated NADPH oxidase, correlating with superoxide production.
Conclusions:
- The developed assay provides a reliable method for measuring NADPH oxidase activity in adherent macrophages.
- This assay simplifies the study of enzymatic oxidative metabolism in macrophages.
- It facilitates research into macrophage function without cell suspension or fractionation.