Adult thymus-derived cMaf+ROR?t+?d T cells lack Scart2 chromatin accessibility and do not reach periphery
T cell receptor (TCR) V?4+expressing ?dT cells can be divided into IFN-? and IL-17-producing effector T cell subsets. A bias towards ?d17 effector fate decisions is observed during early ontogeny. In contrast, the existence of V?4+?d17 cells derived from adult thymus is still controversial. In the present work, we used a mouse model where T cells are exclusive generated within an adult thymus. Additionally, we employed single-cell chromatin state analysis from thymocytes of normal mice. A small, but considerable population of immatureCd24+Gzma+V?4 cells was found that exhibit molecular programs of ?d17 cells. These adult thymus-derived immatureCd24a+cMaf+V?4 cells secrete small amounts of IL-17A and IL-17F. Interestingly, do not reach the periphery under steady-state conditions. Furthermore,de novogenerated ?d17-like cells from adult thymus lack transcriptional activity of the Scart2 encoding gene, suggesting that Scart2 is a distinct trait of fetal ?dT cell precursors. Together, this study provides valuable insights into developmental traits of V?4 cells during adulthood and raises the question on signals suppressing the full maturation and/or thymic export of ?d17-like cells within the adult thymus. Overall design: Sort V?4 ?dT cells from thymus and peripheral lymph nodes of adult mice, then perform 5 'Single Cell V(D)J sequencing (10x genomics)