Cutting Edge: Resident Memory CD8 T Cells Express High-Affinity TCRs.

Area of Science:

• Immunology
• Cell Biology
• Neuroscience

Background:

• Tissue-resident memory T (TRM) cells are critical for immune surveillance in non-lymphoid tissues.
• TRM cells act as the first line of defense against pathogens at barrier sites and in organs like the brain.
• The sensing capabilities of TRM cells in relation to their defensive role are not fully understood.

Purpose of the Study:

• To investigate if enhanced antigen (Ag) sensing complements the role of TRM cells as early responders to pathogen invasion.
• To compare the properties of brain-resident TRM cells with splenic memory T cells.

Main Methods:

• Utilized mouse polyomavirus model to study pathogen invasion.
• Assessed binding to MHC class I tetramers and CD8 coreceptor expression on brain-resident CD8 T cells.
• Employed the two-dimensional micropipette adhesion-frequency assay to measure T cell receptor (TCR) affinity.

Main Results:

• Brain-resident TRM cells showed progressive increases in MHC class I tetramer binding and CD8 coreceptor expression.
• TRM cells in the brain and kidney exhibited up to 20-fold higher TCR affinity compared to splenic memory T cells.
• Effector T cells displayed similar high TCR affinity across all tested organs.

Conclusions:

• TRM cells possess retained high TCR affinity, enabling heightened antigen sensitivity.
• This enhanced sensitivity positions TRM cells as crucial front-line defenders against infectious agents.