FIGURE 4.

Assessment of FoxP3 protein levels in presence or absence of SB216763. Again a co-culture of isolated Treg cells and T effector cells in a 1:1 ratio with anti-CD3/CD28 microbeads with and without 5 μm SB216763 was performed. The collective grouping of T effector and Treg cells was fixed and stained with FoxP3-FITC in intervals of 0, 24, 48, and 72 h. Using FACS analysis, we clearly show that CD4⁺CD25⁺ Treg cells co-cultured with CD4⁺CD25⁻ T cells and treated with SB216763 maintain their FoxP3⁺ signature. This striking finding suggests that SB216763 slows FoxP3 cell turnover in vitro. All data are representative of at least two independently performed experiments, gating on CD4⁺CD25^+hiFoxP3⁺ cells.