T Cell Receptor Bias in Humans

The last decade has seen escalating reports of T cell receptor (TcR) bias across all facets of human immunity. These reports describe a phenomenon whereby certain peptide-bound major histocompatibility complexes (pMHC) elicit T cell expansions which bear TcRs with identical or near-identical sequences across unrelated individuals. These observations are indeed curious given the vastness of the naive T cell repertoire and indicate that powerful Darwinian selection forces influence both thymic and post-thymic pMHC-driven selection. This review catalogues examples of selection bias in the human αβ T cell response and presents the proposed mechanisms that steer their supremacy in the blood.