Multiple Constraints at the Level of TCRα Rearrangement Impact Vα14i NKT Cell Development

Abstract

CD1d-restricted NKT cells that express an invariant Vα14 TCR represent a subset of T cells implicated in the regulation of several immune responses, including autoimmunity, infectious disease, and cancer. Proper rearrangement of Vα14 with the Jα18 gene segment in immature thymocytes is a prerequisite to the production of a TCR that can be subsequently positively selected by CD1d/self-ligand complexes in the thymus and gives rise to the NKT cell population. We show here that Vα14 to Jα rearrangements are temporally regulated during ontogeny providing a molecular explanation to their late appearance in the thymus. Using mice deficient for the transcription factor RORγ and the germline promoters T early-α and Jα49, we show that developmental constraints on both Vα and Jα usage impact NKT cell development. Finally, we demonstrate that rearrangements using Vα14 and Jα18 occur normally in the absence of FynT, arguing that the effect of FynT on NKT cell development occurs subsequent to α-chain rearrangement. Altogether, this study provides evidence that there is no directed rearrangement of Vα14 to Jα18 segments and supports the instructive selection model for NKT cell selection.