Figure 6

Suppressive activity of MT-50.1 and MT-50.4 cells. (a) Flow cytometry histogram showing the increased immunosuppressive function of MT-50.4 cells. CFSE-labeled CD4⁺CD25⁻ T cells (5 × 10⁴, responder cells [RCs]) were cocultured with suppressor cells (SCs; PBMC-derived Tregs obtained from a healthy donor [positive suppressor control], MT-50.1, or MT-50.4 cells), in the presence of mature dendric cells (5 × 10³), 100 U/mL of human IL-2, and 10 μg/mL of the anti-human CD3 monoclonal antibody OKT3. The SCs were serially diluted, keeping the same number of RCs at RC:SC ratios of 2:1, 4:1, and 8:1. After 5 days of culture, the CFSE intensity of RCs was measured using a flow cytometer. The dividing cells are toward the left side in the flow cytometry histogram. The proportion (%) of cells that failed to undergo cell division is indicated in the figure. Unstimulated and stimulated RCs in the absence of SCs were used as negative and positive controls for cell division, respectively. (b) Bar graph showing percent suppression of cell division. Data are shown as the mean ± SEM of three independent experiments. Significant differences are shown as *P < 0.05.