Fig. 3.

IDO activity strongly regulates functional immunosuppressive capacity of IFN-γ–licensed MSCs on hydrogel biomaterials. (A and B) The percent proliferating CD4⁺ T cells in the presence of MSC lines, with and without IFN-γ licensing, cultured on (A) fibrin or (B) collagen with and without the addition of anti–PD-L1 antibody or 1-MT, an IDO inhibitor. (C and D) The percent of CD25⁺ CD4⁺ T cells in the presence of MSC lines, with and without IFN-γ licensing, cultured on (C) fibrin or (D) collagen with and without the addition of anti–PD-L1 antibody or 1-MT. n = 3 to 4 for all data sets. Data are presented as means ± SD. Significance is denoted by **P ≤ 0.01 or ****P ≤ 0.0001 by one-way ANOVA with Tukey’s post hoc test; separate comparisons were made between conditions of each cell line.