Figure 2.

CD14⁺ monocytes and IL-10 were required for the immunomodulatory effect of hBMSCs. PBMCs were stimulated with PHA (1 µg/ml) for 1 day and cocultured with hBMSCs for 2 more days. (a) IL-10 was highly expressed by the PBMC/hBMSC coculture but not by PBMCs alone. (b) The inactivation of PBMCs mediated by hBMSCs can be reversed by adding IL-10sR. (c) Monocyte depleted PBMCs (PBMCs^ΔMono) failed to produce high level of IL-10 in the PBMC/hBMSC coculture. (d) IL-10 mRNA was highly expressed in CD14⁺ monocytes but not B cells and T cells in the PBMC/hBMSC coculture. n = 3. BMSCs, bone marrow stromal cells; hBMSCs, human bone marrow-derived mesenchymal stem cells; IFN-γ, interferon-γ IL, interleukin; PBMCs, peripheral blood mononuclear cells; PHA, phytohemagglutinin.