The role of the T-cell receptor (TCR) in αβ/γδ lineage commitment: clues from intracellular TCR staining

Summary: T cells belong to two mutually exclusive lineages expressing either αβ orγδ T-cell receptors (TCR). Although αβ and γδ cells are known to share a common precursor the role of TCR rearrangement and specificity in the lineage commitment process is controversial. Instructive lineage commitment models endow the αβ or γδ TCR with a deterministic role in lineage choice, whereas separate lineage models invoke TCR-independent lineage commitment followed by TCR-dependent selection and maturation of αβ and γδ cells. Here we review the published data pertaining to the role of the TCR in αβ/γδ lineage commitment and provide some additional information obtained from recent intracellular TCR staining studies. We conclude that a variant of the separate lineage model is best able to accommodate all of the available experimental results.