Figure 4:Inhibition of PBMC proliferation by third party MSC: comparison between Q-MSC and F-MSC. PBMC (100,000 or 50,000) were stimulated (S-PBMC) with anti-αCD3/CD28 microbeads during 4 days with or without irradiated (25 Gy) MSC (10/1 or 5/1 PBMC/MSC ratios) added at the beginning of the culture. Proliferation was assessed by analysis of the cell cycle by flow cytometry. One representative experiment is shown. Result are expressed as the percentage of cells present in S+G2M phases (A) and as the percentage of inhibition compared to the stimulated PBMC condition alone (B). Similar results with fresh cells (from flasks) from the same donor are shown in (C) and (D).