Host-pathogen interactions: leukocyte phagocytosis and associated sequelae.

Area of Science:

• Immunology
• Cell Biology

Background:

• Polymorphonuclear leukocytes (PMNs) are crucial for innate immunity, defending against pathogens via phagocytosis and reactive oxygen species (ROS) production.
• Phagocytosis by PMNs not only eliminates microbes but also triggers PMN apoptosis, essential for resolving inflammation.

Purpose of the Study:

• To develop objective, high-throughput flow cytometric methods for evaluating phagocytosis and ROS production in human PMNs.
• To establish flow cytometry assays for measuring phagocytosis-induced PMN apoptosis, encompassing early and late stages.

Main Methods:

• Utilized flow cytometry to assess host cell-pathogen interactions, adapting a common phagocytosis assay system.
• Employed fluorometric probes and selected bacteria/host cells for versatile application.
• Measured early apoptosis via surface phosphatidylserine exposure and late apoptosis through chromatin condensation and DNA fragmentation.

Main Results:

• Developed flow cytometry assays providing objective, high-throughput quantification of PMN phagocytosis and ROS production.
• Successfully adapted methods to measure phagocytosis-induced PMN apoptosis, detecting both early and late apoptotic markers.
• Demonstrated the assays' capacity for rapid and accurate assessment of critical PMN functions.

Conclusions:

• The developed flow cytometry methods offer a significant advancement over traditional microscopy for studying PMN functions.
• These assays provide a versatile and robust platform for analyzing innate immune responses, particularly host-pathogen interactions and inflammatory resolution.
• The methods enable rapid, accurate, and objective evaluation of key PMN processes, facilitating further research in immunology and related fields.