T-cell receptor αβ chain pairing is associated with CD4+ and CD8+ lineage specification

While a highly diverse T-cell receptor (TCR) repertoire is the hallmark of a healthy adaptive immune system, relatively little is understood about how the CD4+ and CD8+ TCR repertoires differ from one another. We here utilize high-throughput single T-cell sequencing to obtain approximately 100,000 TCR {beta} chain pairs from human subjects, stratified into CD4+ and CD8+ lineages. We reveal that substantial information about T-cell lineage is encoded by V{beta} gene pairs and, to a lesser extent, by several other TCR features such as CDR3 length and charge. We further find that the strength of association between the {beta} chain and T-cell lineage is surprisingly weak, similar in strength to that of the chain. Using machine learning classifiers to predict T-cell lineage from TCR features, we demon-strate that {beta} chain pairs are significantly more informative than individual chains alone. These findings provide unprecedented insight into the CD4+ and CD8+ TCR repertoires and highlight the importance of {beta} chain pairing in TCR function and specificity.