FIGURE 2. Foxp3-dependent suppression and lineage stability.

a, FACS purified T_r or T_fn cells were compared for their ability to suppress CD25^-CD4⁺ T-cell proliferation in the presence of concavalin A and T-cell-depleted splenic antigen presenting cells. Data represent mean and standard deviation for triplicate wells; results are representative of four separate experiments. b–d, To examine suppressor activity in vivo, T_r or T_fn cells were co-transferred with allelically marked effector T cells into lymphopenic animals. Sorted Ly5.1⁺CD45RB^highCD25^-CD4⁺ effector T cells (T_eff, 3  10⁵) were transferred into B6.SCID mice alone or with sorted T_R or T_fn cells (10⁵). Five weeks after transfer, splenocytes were enumerated (b) and lymph node and spleen cells were analysed by flow cytometry. Cell size of the effector T-cell population (c) and abundance and GFP expression of the donor T_r or T_fn cell populations (d) are shown. Data are representative of two independent experiments. e, Quantification of Foxp3 cDNA prepared from the indicated cell populations. For peripheral cells, error bars represent mean and maximum/minimum for biological duplicates.