Inhibition of antigen-specific CTL generation by CD4⁺CD25^brightFoxp3⁺ Tregs. Bulk T cells stimulated by IDO-expressing, mature moDCs were sorted cytofluorographically to collect CD4⁺CD25^bright and CD4⁺CD25^neg candidate Tregs. These were then added 1:1 with responder T cells to mature moDCs that were electroporated before terminal maturation with WT1 mRNA. After 7 days' culture, WT1-specific target cell lysis was measured by a flow cytometric PKH-26 cell lysis assay and compared between cultures containing no candidate Tregs (baseline lysis, ■), CD4⁺CD25^bright T cells (□), and CD4⁺CD25^neg T cells (▩; average of triplicate means ± SEM, n = 3 independent experiments; P values indicated on graph).