TGF-β does not interfere with IFN-γ–induced antigen cross-presentation by MSCs. (A) TGF-β– or IFN-γ–treated MSCs primed with OVA (1 mg/mL) for 18 hours were cocultured at the indicated density with OT-I CD8⁺ T cells for 48 hours. Analysis of the assay was performed as described previously in Figure 2A. The results show means of triplicates ± SD of 1 of 3 representative experiments. (B) Flow cytometry analysis of surface expression of MHC class I (H2-K^b) on MSC treated with different doses of TGF-β only (top panel) or with different doses of TGF-β in combination with IFN-γ (10 ng/mL; bottom panel). (C) Quantitative RT-PCR analysis of Tap1 (left panel) and Lmp2 (right panel) mRNA levels in MSC treated with TGF-β (1 ng/mL), IFN-γ (10 ng/mL), or the combination of both for 48 hours. Relative quantification (RQ) was calculated by normalizing to 18S mRNA levels. Figure shows means of triplicates ± SD. (D) Western blot analysis of LMP2 on MSCs treated or untreated with TGF-β (1 ng/mL) and IFN-γ (10 ng/mL) for 8, 24, and 48 hours (right panel). Loading control was performed on β-tubulin.