Expression of 17195TCR on human Tregs and upregulation of Foxp3 and GARP by stimulation with FVIII-2191-2220. 17195TCR and mock-transduced Tregs (prepared as in Figure 2A) were maintained in culture for 10 days and then reactivated for 48 hours with irradiated DR1-PBMCs and FVIII-2191-2220 (0.5 μg/mL) or OVA peptide (0.5 μg/mL) plus IL-2 (200 U/mL). GFP expression in transduced cells was measured by FACS (left contour plot). The right contour plots indicate subsequent Foxp3 and GARP expression in gated GFP⁺ cells. Induction of Foxp3 and GARP by specific antigen was calculated by comparing the Foxp3⁻GARP⁻ cell counts (lower left gate and number) and the Foxp3⁺GARP⁺ cell counts (upper right gate and number) in the right contour plots.