Use of TCR ADV gene segments by the δ chain is independent of their position and of CD3 expression

The CD3 signaling complex is required for cell surface expression and selection of both α β and γ δ TCR. In this study we analyzed TCRδ transcripts in both wild‐type and CD3‐ϵ‐eficient mice. We show that the repertoire of ADV segments used by the δ chain is unchanged in the latter. Not all ADV genes participate in making up the TCRD repertoire. However, their use does not depend on their distance from the other TCRD‐forming segments. For example ADV12, situated at more than 870 kb from the DD region, is expressed as part of TCRD transcripts, whereas ADV8, members of which are proximal to the DD region, is not. These data suggest that the accessibility of ADV8 gene segments is differentially regulated during T cell development in the thymus. Taken together, our results suggest that TCRA and TCRD rearrangements are independently controlled, and that the absence of TCRA expression in CD3‐ϵ‐deficient mice is not due to a lack of accessibility of the ADV gene segments but rather to inaccessibility of the AJ gene region.