Vδ repertoire during thymic ontogeny suggests three novel waves of γδ TCR expression.

Taking advantage of a PCR technique that allows amplification of all variable region genes with equal efficiency, we defined three novel waves of TCR δ-chain transcription during thymic ontogeny. The canonical DV101-D2-J2 rearrangement was confined to a narrow window from days 14 to 18 of gestation, indicating that the postulated two consecutive γδ precursor waves bearing this canonical DV101 rearrangement will coincide on day 16. Neonatal δ-chain transcripts used a second wave of diverse Vα gene segments that are exclusively located in the δ locus-proximal gene cluster of intermingled single members of different Vα subfamilies. In the adult, only expression of a clan of three homologous subfamilies, ADV7, DV104, and ADV17, persists. The members of the ADV7 subfamily are also scattered across the α locus, but their usage does not show the position-dependent bias of the other Vα-to-δ rearrangements.