Single-cell observation of calcium signals in T cells and antigen-presenting cells during antigen presentation

Area of Science:

• Immunology
• Cell Biology
• Calcium Signaling

Background:

• T-cell activation and antigen presentation are critical immune processes.
• Intracellular calcium ion (Ca2+) dynamics play a key role in immune cell function.
• Antigen-presenting cells (APCs) are essential for initiating T-cell responses.

Purpose of the Study:

• To investigate intracellular calcium ion mobilization in T-cell hybridomas and APCs during cell-cell interaction.
• To understand the role of calcium signaling in T-cell activation, apoptosis, and APC function.
• To examine the effect of chemical modification of APCs on T-cell interaction and calcium signaling.

Main Methods:

• Confocal fluorescence microscopy was employed to visualize intracellular calcium ion dynamics.
• T-cell hybridomas and APCs were utilized to study cell-cell interactions.
• Chemical modification of APCs using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide was performed.

Main Results:

• Non-activated T-cell hybridomas showed no calcium signal upon antigen presentation.
• Activated T-cell hybridomas exhibited rapid intracellular calcium ion increase post-antigen presentation, followed by apoptosis.
• APCs displayed calcium signals during interaction with T-cell hybridomas, irrespective of T-cell activation status.
• Chemical modification of APCs inhibited surface MHC class II cap formation and suppressed T-cell interaction-induced calcium signals.

Conclusions:

• Intracellular calcium ion mobilization is differentially regulated in T-cells and APCs during immune interactions.
• Antigen presentation induces a calcium-dependent apoptotic pathway in activated T-cells.
• APCs exhibit robust calcium signaling during T-cell interactions, which can be modulated by APC surface molecule modification.