The Biology of Recent Thymic Emigrants

The generation of the TCRαβ lineage of T cells occurs in the thymus through a series of orchestrated developmental events that result in a carefully selected population of CD4 or CD8 lineage–committed TCR⁺ thymocytes capable of recognizing foreign antigen in the context of self MHC. T cells first exit the thymus in a phenotypically and functionally immature state and require an approximately 3-week period of post-thymic maturation before transitioning into the mature T cell compartment. A greater understanding of recent thymic emigrant biology has come with the development of methods to exclusively identify and isolate this population for further characterization. I now review current knowledge about the phenotype and function of this key but understudied population of peripheral T cells.