Treg cells inhibit anti-CD3 and CEF-induced proliferation of CD8⁺ T cells. (A) Representative histograms depicting the CFSE profile of CD8⁺ T cells from a healthy donor stimulated with coated anti-CD3 mAb for 5 days (left panel) or with CEF mix for 7 days (right panel), in the presence of CD4⁺CD25⁻ T cells (top row) or Treg cells (bottom row). The percentage of CD8⁺ T cells that have divided after stimulation (CFSE^low) is indicated. (B) Pooled data from 11 donors showing the percentage of inhibition of CD8⁺ T-cell proliferation after anti-CD3 or CEF stimulation in the presence of Treg cells in comparison with proliferation in the presence of CD4⁺CD25⁻. The mean values are depicted with horizontal lines.