Fig. 3

The definition and identification for Th cells from the perspective of thymic development of Th cells. a Schematic summary of the development of Th cells in the thymus cortex and medulla. b Schematic illustration of Th cells versus innate T cells among CD4⁺ αβ T cells. Th cells are, in the strict definition, MHCII-restricted CD4⁺ αβ T cells and PLZF negative. The identification methods for Th cells are shown. DC, dendritic cell; PLZF, promyelocytic leukemia zinc finger; TEC, thymic epithelial cell; TRA, tissue-restricted antigen; UEA, ubiquitous-expressed antigen