Figure 3.

MSCs enhance the ability of CD8⁺CD28⁻ T cells to inhibit IFN-γ production by responder CD4⁺ T cells and induce the apoptosis of activated CD4⁺ T cells. Flow cytometry plots represent the levels of IFN-γ secreted by the CD4⁺ T cells. The CD8⁺CD28⁻ T cells and MSCs-pre-treated CD8⁺CD28⁻ T cells were added respectively at a ratio of 1∶1, and IFN-γ production was significantly downregulated by MSCs-pre-treated CD8⁺CD28⁻ T cells (a, b). The purified activated T cells (CD4⁺CD25⁺ T cells) were cocultured with CD8⁺CD28⁻ T cells and MSCs-pre-treated CD8⁺CD28⁻ T cells at a ratio of 1∶1, and the cytotoxity of CD8⁺CD28⁻ T cells was evaluated by Annexin V-positive cells within the total CD4⁺ T-cell population (c, d) The bar graphs indicate the means±s.d.; statistically significant differences are indicated as follows: *P<0.05 and **P<0.01, n=3. MSC, mesenchymal stem cell.