Galectin-1 knockdown in MSCs resulted in a strongly reduced inhibition of IL-2/OKT3–stimulated PBMCs. (A) Proliferation of HLA-mismatched PBMCs in the absence or presence of MSCs. MSC^wt and MSC^contr showed comparable inhibition of PBMC proliferation, whereas MSC^G1▾ showed significantly reduced antiproliferative effects. (B) IFNγ-secretion by PBMCs measured 48 hours after stimulation with IL-2/OKT3 in the presence of HLA-mismatched MSCs. MSC^G1▾ showed a significantly reduced inhibition of IFNγ secretion by PBMCs compared with MSC^wt and MSC^contr. Data are shown as means (± SD) of quadruplicates (n = 3).