Effect of MSCs on viral or alloantigen-induced IFN-γ production from PBMCs. (A) PBMCs from 6 healthy donors (ND) were stimulated with irradiated (irr) allo PBMCs, irr autologous (autol) LCL or pp65 peptides in the presence or absence of MSCs for 5 days. Cells were then analyzed by Elispot to determine the frequency of IFN-γ SFCs. (B) Representative FACS plot of intracellular IFN-γ staining from PBMCs gated on CD3⁺ T cells stimulated with irr autologous LCL or pp65 peptides in the presence or absence of MSCs.