IL-2/anti-IL-2mAb complexes enhanced the inhibitory activity of Tregs in NOD mice as measured by CFSE assay. Female NOD mice 6–8 week old were left untreated or treated with IL-2/anti-IL-2mAb. On day 5 cells were isolated from lymphoid organs, CD4+CD25+ Tregs were purified from both groups, and co-cultured with equal number of CFSE-labelled CD8+Thy1.1+ 8,3 T cells in the presence of anti-CD3/anti-CD28 beads (2:1 beads: cell ratio). 3 days later, cells were stained with antibodies (anti-CD4, anti-CD8, anti-Thy1.1), and analyzed on a flow cytometer. The CFSE dilution (% proliferation) of 8.3 CD8+ T cells (gated on CD8, Thy1.1 double positive population) was plotted. Shown are the data from one representative experiment out of two independent experiments with similar results.