fig2

Figure 2. Characterization of T_reg cells and subsets: CD4⁺ T cells egress from the thymus and differentiate in blood and tumor tissue. Depending on the degree of CD45RA and FOXP3 expression, CD4⁺ are defined as nT_reg cells. CD4⁺ or nT_reg cells egress into the periphery, where either cell population is subsequently altered and selected for different types of T_reg cells. Based on the “selection model”, CD4⁺ naïve cells are selected to transition into iT_reg cells, differing in their functional status as “Tr1 cells” or Th3 cells. FOXP3: Forkhead box protein P3; nT_reg: natural T regulatory cells; iT_reg: induced T_reg cells; Tr1 cells: type 1 T_reg cells; Th3 cells: T helper 3 cells.