Proliferation assay following in vitro stimulation of T cells isolated from hemophilia A mice. Two animals per group were untreated (n = 2, ▵), hFVIII plasmid-treated (n = 2, ○), or hFVIII plasmid-treated receiving immunomodulation by combination of Ctla4 and MR1 (n = 2, ▴, animals from the group shown in Figure 3E,F). Splenic T cells were isolated from hemophilia A mice and cultured in the presence of hFVIII for 3 days. T-cell proliferation was measured in triplicate against a range of FVIII concentrations. Each data set represents the mean ▵cpm obtained from 2 mice.