Quantifying biomass changes of single CD8+ T cells during antigen specific cytotoxicity

Area of Science:

• Immunology
• Cell Biology
• Biophysics

Background:

• Quantifying cytotoxic T cell responses is crucial for immunotherapy but current methods have limitations.
• Existing techniques often use bulk measurements or fluorescent labels, hindering analysis of primary cells like human T lymphocytes.
• Directly identifying single activated T cells is challenging with current methodologies.

Purpose of the Study:

• To develop a label-free, quantitative method for tracking single T cell-mediated cytotoxic events in real-time.
• To assess T cell activation and cytotoxic activity using live cell interferometry (LCI).
• To enable rapid identification of specific, activated patient-derived T cells for cancer immunotherapy.

Main Methods:

• Utilized live cell interferometry (LCI), a label-free microscopy technique measuring intracellular mass via light phase shift.
• Imaged cytotoxic T lymphocytes (CTLs) interacting with and killing target cells in a mixed cell population.
• Quantified changes in both T cell and target cell mass during cytotoxic events.

Main Results:

• Observed a characteristic 20-60% decrease in target cell mass within 1-4 hours post-attack.
• Detected a significant 4-fold increase in T cell mass accumulation rate at the onset of cytotoxicity.
• Demonstrated a 2-3 fold increase in T cell mass compared to unresponsive T cells, indicating activation.

Conclusions:

• LCI provides a direct, label-free, and quantitative method to assess T cell activation and cytotoxic function.
• This technique allows for kinetic monitoring of single T cell-mediated killing events while maintaining cell viability.
• LCI offers a rapid approach for identifying activated patient-derived T cells, with potential applications in personalized cancer immunotherapy.