Atomistic TCR-ligand interactions instruct memory T-cell differentiation

Area of Science:

• Immunology
• Cellular Biology
• Molecular Biology

Background:

• Memory T cells are crucial for adaptive immunity, providing rapid protection against re-infections and cancer.
• The molecular mechanisms governing the differentiation of naive CD8+ T cells into distinct memory subsets (TCM and TEM) remain incompletely understood.

Purpose of the Study:

• To elucidate the molecular basis of CD8+ T cell memory fate determination.
• To investigate the relationship between T-cell receptor (TCR) signaling polarity and the bifurcation into central memory (TCM) and effector memory (TEM) T cell subsets.

Main Methods:

• Single-cell transcriptomics with TCR sequencing of 242 murine CD8+ TCRαβ clonotypes specific for an influenza A virus (IAV) epitope.
• Biophysical measurements of force-dependent TCR-pMHC interactions.
• In vivo memory development studies and structural analyses.

Main Results:

• Distinct TCR subunit engagement biases correlate with memory fate: TCRβ-driven engagement favors TCM, while TCRα-driven engagement favors TEM.
• Bipolar clonotypes (TBP) show balanced signaling, larger expansions, and broader crossreactivity.
• TCM-associated TCR sequences exhibit greater potential for recognizing IAV mutants, indicating a complementary crossreactivity strategy.

Conclusions:

• TCR diversity anticipates pathogen evolution, while divergent TCR signaling pathways regulate memory T cell fate.
• Understanding these mechanisms has implications for developing effective adoptive T-cell immunotherapies.
• Fine-tuned TCR-ligand interactions at the atomic level modulate mechanical signals, influencing T cell memory development and function.