B6 strains. Trd1 contains several genes encoding transcription factors of yet unclear function.

One of them, Btbd9 is a transcription factor containing a POZ domain. Two other members of this family have been described, ThPok and PLZF, implicated, respectively, in CD4 [20] and NKT lineage commitment [21] turning Btbd9 into a candidate for the control of Treg-cell lineage Selumetinib in vitro choice. The Trd1 locus, as it is currently defined, contains Idd16, raising the intriguing possibility that the altered thymic Treg-cell differentiation in NOD vs. B6 mice may be linked to diabetes susceptibility. However, whereas hybrid mice display similarly low levels of Treg cells as B6 mice, they are as susceptible to diabetes as NOD animals. Together, these data therefore strongly suggest that the altered Treg-cell development caused Cilomilast cost by the Trd1 region is functionally dissociated from diabetes onset and progression. The genes

involved in Treg-cell development and diabetes susceptibility are therefore probably, but not necessarily, distinct. Other genetic loci controlling the altered Treg-cell development in NOD vs. B6 mice have been identified [11] but they do not correspond to diabetes susceptibility loci. It appears therefore very unlikely that the quantitatively altered Treg-cell development in NOD mice plays a major role in diabetes susceptibility. In conclusion, we have identified a locus that quantitatively controls thymic Treg-cell development. The atypically high levels of Treg cells developing in NOD mice from appear functionally

dissociated from their susceptibility to diabetes. Identification of the responsible genes and mechanisms will shed light on the still incompletely defined processes involved in the quantitative control of Treg-cell development in the thymus and potentially on commitment of precursors to the Treg-cell lineage. All mice were females of 6–8 weeks. C57BL/6N (B6) mice were purchased from Janvier (Le Genest St Isle, France), C57BL/10 (B10) and NOD strains from Charles River (Les Oncins, France), MHC°, C57BL/6, NOD.B6-R76 (R76), NOD.B6-R156 (R156), and NOD.B6-R115 (R115) mice were bred in our facilities. All experiments involving animals were performed in compliance with the relevant laws and institutional guidelines (INSERM; approval # 31–13, ethical review # MP/02/32/10/03). The following antibodies and secondary reagents were used for phenotypic analysis: PE-Cy7, Pacific Blue, and allophycocyanin-labeled anti-CD4 (GK1.5), FITC, AlexaFluor 700, and allophycocyanin-labeled anti-CD8 (53.6.7), PE, PE-Cy7 and allophycocyanin-labeled anti-CD25 (PC61), PE, and allophycocyanin-labeled anti-TCR (H57), PE, and allophycocyanin-labeled Foxp3 (FJK-16s), biotin-labeled anti-CD122 (5H4), biotin-labeled CD127 (A7R34), (eBioscience, San Diego, CA, USA), PE-labeled Ki67 (B56) (BD Bioscience, NJ, USA).