MSC^IFNγR1− and MSC^wt inhibit proliferation of PBMCs to a similar extent. (A) Proliferation of HLA-mismatched PBMCs in the absence (■) or presence (▩) of MSC^wt; representative result of 5 independent experiments. MSCs inhibited PBMC proliferation in a dose-dependent manner. (B) PBMCs were inhibited by MSCs with IFNγR1 defect to a similar extent as by MSC^wt (representative of n = 5). (C) Proliferation of HLA-mismatched PBMCs in the absence (■) or presence (▨) of MSC^wt, when human rIFNγ was added to the cultures. PBMCs cocultured with MSC^wt proliferated more vigorously in presence of rhIFNγ (representative of n = 5). (D) This effect mediated by rhIFNγ was even stronger when PBMCs were cocultured with MSC^IFNγR1− (representative of n = 3). Data are shown as means of triplicates plus or minus standard deviation (±SD) of one representative experiment.