Assembled DJβ Complexes Influence TCRβ Chain Selection and Peripheral Vβ Repertoire

TCR beta chain repertoire of peripheral alpha beta T cells is generated through the stepwise assembly and subsequent selection of TCR beta V region exons during thymocyte development. To evaluate the influence of a two-step recombination process on V beta rearrangement and selection, we generated mice with a preassembled D beta 1J beta 1.1 complex on the J beta 1(omega) allele, an endogenous TCRP allele that lacks the D beta 2-J beta 2 cluster, creating the J beta 1(DJ beta) allele. As compared with J beta 1(omega/omega) mice, both J beta 1(DJ beta/omega) and J beta 1(DJ beta/DJ beta) mice exhibited grossly normal thymocyte development and TCR beta allelic exclusion. In addition, V beta rearrangements on J beta 1(DJ beta) and J beta 1(omega) alleles were similarly regulated by TCR beta-mediated feedback regulation. However, in-frame V beta DJ beta rearrangements were present at a higher level on the J beta 1(DJ beta) alleles of J beta 1(DJ beta/omega) alpha beta T cell hybridomas, as compared with on the J beta 1(omega) alleles. This bias was most likely due to both an increased frequency of VP-to-DJ beta rearrangements on J beta 1(DJ beta) alleles and a preferential selection of cells with in-frame V beta DJ beta exons assembled on J beta 1(DJ beta) alleles during the development of J beta 1(DJ beta/omega) alpha beta T cells. Consistent with the differential selection of in-frame V beta DJ beta rearrangements on J beta 1(DJ beta) alleles, the V beta repertoire of alpha beta T cells was significantly altered during alpha beta TCR selection in J beta 1(DJ beta/omega) and J beta 1(DJ beta/DJ beta) mice, as compared with in J beta 1(omega/omega) mice. Our data indicate that the diversity of DJ beta complexes assembled during thymocyte development influences TCR beta chain selection and peripheral VP repertoire. The Journal of Immunology, 2009, 182: 5586-5595.