Gene expression in lymphocytes challenged with PBL and MSC. Responder PBL (n=3; ■, ▲, and ●) were co-cultured with a pool of allogeneic PBL (PBL), allogeneic MSC (MSC) and pool of allogeneic PBL with addition of MSC (PBL+MSC) for 24 and 48 h. Gene expression of CD25, IFN-γ, FoxP3, CTLA-4 and IL-10 were determined by real-time quantitative PCR and are reported as times the expression in a resting PBL.