Dwell times of Tconvs versus Tregs with DCs in the presence of blocking anti–CTLA-4 Fab. CD4⁺CD25⁺ and CD4⁺CD25⁻ T cells from DO11.10 x Ctla4^+/+ mice were incubated with anti–CTLA-4 Fab, or isotype anti–hamster IgG control. After 30 minutes, contact times were measured between DCs and T cells in the absence (DC) and presence of OVA peptide (DC-OVA). Differences between the mean values were tested using 2-tailed Student t test (GraphPad Prism 5.0). P < .05 was considered significant. Data are representative of 3 separate experiments.