Atomistic TCR-ligand interactions instruct memory T-cell differentiation 2330211

Abstract Introduction Memory T cells generate durable and rapid protection following re-exposure to an infectious pathogen or a cancerous transformation. How naive CD8+ T cells develop into memory T cells that bifurcate into long-lived central (TCM) versus effector (TEM) subsets after an antigen encounter remains ill-defined at the molecular level. Methods We dissect the T-cell receptor (TCR) repertoire of 242 murine CD8+ TCRαβ clonotypes specific for the peptide-major histocompatibility complex molecule (pMHC) comprising an immunodominant influenza A virus (IAV) epitope NP366-374 presented by H-2Db. Using single-cell transcriptomics with TCR sequencing, biophysical measurements of force-dependent TCR-pMHC interactions, in vivo memory development, and structural analyses, we integrate these data to define relationships between signaling polarity and memory fate. Results TCM and TEM polarities reflect distinct subunit-specific mechanotransduction biases: TCM-associated TCRs favor TCRβ-driven pMHC engagement, whereas TEM-associated TCRs preferentially favor TCRα-driven engagement. Moreover, “bipolar” clonotypes (TBP) capable of generating both memory subsets exhibit balanced signaling, the largest average clonal expansions, and broad heterosubtypic crossreactivity. In contrast, TCM with variegated TCR sequences predominantly form clonal singlets yet display the greatest expansion after IAV rechallenge, revealing complementary memory niche strategies. Weak, force-sensitive TCR bonds are pervasive across the repertoire, most prominently among TCM clonotypes. Subtle atomic-level differences in TCRαβ engagement of peptide and/or MHC modulate mechanical load transmission through the TCR-CD3 complex, differentially shaping downstream tyrosine phosphorylation and memory fate. Conclusion TCR diversity anticipates epitope-specific pathogen evolution, whereas divergent TCR signaling regulates memory fate with implications for adoptive T-cell immunotherapies seeking to maximize persistence and minimize functional exhaustion. Funding Source National Institutes of Health grant 1P01AI143565 Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)