Cytotoxic T lymphocytes targeting a conserved SARS-CoV-2 spike epitope are efficient serial killers

Area of Science:

• Immunology
• Cell biology
• Bioengineering

Background:

• Humoral immune responses are well-studied, but cellular immunity, especially T cell responses, is less understood for infections, cancers, and vaccines.
• T cells are vital for long-term immunity against viral infections like SARS-CoV-2, even as antibody responses decline.
• Current methods for assessing T cell responses, like T-cell receptor repertoire screening, do not measure functional capacity or cytotoxic ability.

Approach:

• Developed a novel imaging platform using time-lapse imaging microscopy in nanowell grids (TIMING) to analyze individual T cell interactions.
• Integrated machine learning to analyze thousands of videos of T cells with SARS-CoV-2 specificity interacting with and eliminating infected target cells.
• Used spike protein as a surrogate for viral infection to assess T cell effector functions, including cytokine secretion and cytotoxicity.

Key Points:

• Demonstrated that cytotoxic T lymphocytes from convalescent patients targeting a conserved SARS-CoV-2 epitope are 'serial killers'.
• These T cells can eliminate multiple infected targets, providing direct evidence of their functional capacity.
• The study highlights the importance of cellular immunity for sustained protection against viral threats.

Conclusions:

• The TIMING platform offers a powerful tool to assess the functional capacity of T cells and their cytotoxic activity.
• Findings provide fundamental insights into the immunology of vaccines and recovery from infections, particularly SARS-CoV-2.
• Implications for developing vaccines that induce broad, sustained cellular immunity and for monitoring individuals exposed to SARS-CoV-2.