Simultaneous Membrane Capacitance Measurements and TIRF Microscopy to Study Granule Trafficking at Immune Synapses

Area of Science:

• Immunology
• Cell Biology
• Biophysics

Background:

• Exocytosis, the process of releasing cellular contents, is crucial for immune cell function.
• Understanding the dynamics of cytotoxic granule release is key to immune synapse function.
• Existing methods lack the temporal resolution to fully capture exocytosis events.

Purpose of the Study:

• To combine whole-cell capacitance measurements with TIRFM for high-resolution imaging of cytotoxic granule release.
• To identify specific capacitance changes linked to cytotoxic granule fusion events.
• To characterize cytotoxic granule behavior at the immune synapse prior to exocytosis.

Main Methods:

• Whole-cell capacitance measurements to monitor membrane fusion events in real-time.
• Total internal reflection fluorescence microscopy (TIRFM) for high-resolution imaging of fluorescently labeled granules.
• Coupling of capacitance recordings with TIRFM to correlate electrical and visual data.

Main Results:

• Successfully identified capacitance steps corresponding to individual cytotoxic granule release events.
• Visualized the behavior and localization of cytotoxic granules at the immune synapse before fusion.
• Established a method to link biophysical measurements of exocytosis with direct imaging of granule dynamics.

Conclusions:

• The combined approach offers a powerful tool for studying immune synapse function.
• This technique allows detailed characterization of cytotoxic granule exocytosis with high temporal and spatial resolution.
• Enables investigation of calcium's role in cytotoxic granule release and immune synapse processes.