TCR repertoire analysis reveals phosphoantigen‐induced polyclonal proliferation of Vγ9Vδ2 T cells in neonates and adults.

The Vγ9Vδ2 T cell subset is the major γδ T cell subset in human peripheral blood and has the unique ability to contribute to immune surveillance by detecting pyrophosphorylated metabolites of isoprenoid synthesis, termed phosphoantigens (pAgs). Vγ9Vδ2 T cells are first detected at midgestation and show postnatal expansion. Interestingly, neonatal Vγ9Vδ2 T cells display a higher TCR repertoire diversity with more public clonotypes and lower pAg responsiveness than in adults. Notably, it is not known whether postnatal changes occur by TCR‐dependent reactivity to pAg exposure. Here, we applied next‐generation sequencing of γδ TCR repertoires to understand potential differences in the pAg‐mediated response of neonatal and adult Vγ9Vδ2 T cells at the level of the expressed γδ TCR. We observed a polyclonal pAg‐induced response of neonatal and adult Vγ9Vδ2 T cells, albeit neonatal γδ T cells showed less in vitro pAg responsiveness. Neonatal Vγ9Vδ2 T cells displayed a less pronounced bias for Jδ1 usage and a more frequent use of Jδ2 or Jδ3 that remained stable after pAg exposure. In addition, public and private Vδ2 TRD clones took part in the polyclonal pAg‐induced response in neonates and adults. In conclusion, adult and neonatal Vγ9Vδ2 T cells both undergo polyclonal pAg‐induced proliferation, whereas especially adult Vγ9Vδ2 T cells display a high stability at the level of the expressed TCR repertoire. [ABSTRACT FROM AUTHOR]