The suppressive function of pltLys-iTreg cells on T-cell proliferation in vitro. CD4⁺EGFP⁺ Treg cells induced in vitro by pltLys or purTGFβ were sorted and cocultured with violet-labeled CD4⁺ T cells (T effectors) at various ratios in the presence of anti-CD3/CD28 antibodies for 72 hours. Cells were harvested and stained with anti-CD4 antibody. The daughter effector cells were analyzed by flow cytometry. Suppression assays were analyzed using the Proliferation Platform in FlowJo software. Representative histograms from flow cytometry (A) and summarized data (B). Experiments were repeated 6 times. “DI” represents division index, which is the average number of cell divisions that a cell in the original population has undergone.