FOXP3 and diabetes mellitus: Injection of 5 × 105 diabetogenic CD4+BDC2.5+ T cells with a naïve surface marker phenotype resulted in overt diabetes at day 14.5 ± 1.0 in recipient mice of the otherwise untreated Ctrl group (Figure 5B, left), while co-transfer of as few as 1 × 105 BDC2.5+Foxp3+ Treg cells were sufficient to suppress diabetes development.