IFNγ levels in MHC-II expression and APC function of MSCs. (A) APC assays were established as for Figure 1B, in the presence or absence of 1 μg/mL anti-IFNγRI or isotype control. At different times, culture media were determined for IFNγ levels and the CD4⁺ cells, and flow cytometry was done with the adherent cells colabeled with FITC anti-CD105 (for MSC) and PE anti–HLA-DR. Figure represents 4 different experiments. (B) Studies were set up as for Figure 1B, except that MSCs were pretreated with IFNγ-RI antibody or isotype control. The results are presented as the mean ± SD (n = 5). Background disintegrations per minute (unactivated CD4⁺ and activated CD4⁺) were 577 and 653, respectively. *P < .05 versus cultures of pulsed/activated/isotype control. (C) MSCs were incubated for 2 or 12 hours with IFNγ at 10 or 100 U/mL IFNγ. After this, cells were washed and then used in APC assays. *P < .05 versus unstimulated or 10 U/mL IFNγ;**P < .05 versus similar cultures with 100 U/mL IFNγ.