Figure 4.

Activation-induced CD4⁺CD25⁺ regulatory T cells are cell-contact dependent and cytokine independent. Proliferation and suppression of freshly isolated CD4⁺CD25– T cells by CD4⁺CD25⁺ (a, left panel, and b) or CD4⁺CD25– (a, right panel) cells, which were generated by activation CD4⁺CD25– PBMCs with plate-bound anti-CD3/soluble anti-CD28 for 14 days. (a) CD4⁺CD25⁺ and CD4⁺CD25– cells from the same culture were sorted and cultured alone, together with freshly isolated CD25– cells, or separated by a transwell. Sorted cells are indicated in bold type and freshly isolated cells in normal type. (b) Cells were cultured in the presence of 10 μg/ml anti–IL-10, anti-TGF-β, or an isotype control Ab (RIgG2a). These data are from one experiment but are representative of two separate experiments.