Direct measurement of phagolysosomal esterase activity

Area of Science:

• Cell Biology
• Enzymology
• Immunology

Background:

• Phagolysosomes are crucial cellular compartments for pathogen degradation.
• Esterase activity within phagolysosomes plays a role in cellular defense mechanisms.
• Direct measurement of phagolysosomal esterase activity in intact cells is challenging.

Purpose of the Study:

• To develop a novel method for directly measuring esterase activity within phagolysosomes.
• To quantify esterase activity in intact human peripheral neutrophils without cell lysis.

Main Methods:

• Preparation of decanoyl fluorescein-binding microspheres.
• Phagocytosis of microspheres by human peripheral neutrophils.
• Measurement of fluorescence intensity using a flow cytometer to assay esterase activity.

Main Results:

• Decanoyl fluorescein on microspheres was hydrolyzed by lysosomal esterase within phagolysosomes.
• Hydrolysis converted non-fluorescent microspheres to fluorescent ones.
• Esterase activity was successfully measured in intact neutrophils using fluorescence intensity.

Conclusions:

• A new, direct method for assaying phagolysosomal esterase activity has been established.
• This method allows for the measurement of esterase activity in single, intact neutrophils.
• The developed technique provides a valuable tool for studying phagolysosomal function.