The Role of the T Cell Receptor Sequence in Shaping T Cell Functional Fate

The T cell receptor (TCR) has long been studied through the lens of antigen recognition, with decades of work characterizing how the TCR sequence specifies the peptide-MHC ligands a T cell can engage. Yet a growing body of evidence indicates that the TCR sequence carries another dimension of functional information: it biases the transcriptional fate a T cell is likely to adopt. In this review, we synthesize the evidence that TCR sequence features shape T cell differentiation during both thymic development and peripheral responses. We provide an overview of the landscape of T cell fates and the TCR structure, describe advancements in technologies to profile T cell phenotype and TCR sequence, and outline computational strategies for modeling the relationship between them. We specifically examine four reproducible axes of covariation between TCR sequence and T cell fate, including innate-like lineages, regulatory T cells, CD4 versus CD8 commitment, and peripheral memory formation. Understanding the probabilistic fate biases encoded by the TCR may advance our ability to interpret repertoires in health and disease and engineer next-generation cellular therapies.