Figure 4.

Effects of OX40L treatment on CD4⁺CD25⁺Foxp3⁺ mature Tregs and CD4⁺CD25⁺Foxp3⁻ Treg precursors ex vivo. (a) CD4⁺CD25⁺Foxp3⁺ mature Tregs sorted from Foxp3.eGFP murine CD4⁺SP thymocytes were treated with IL-2 (25 U/ml) alone (top) and IL-2+ OX40L-Fc (5 μg/ml) for 0–120 h. Cell proliferation was measured by Cell Trace Violet dilution. Numbers represent percentages of proliferating Tregs at indicated time intervals. (b) Bar graph summarizing results shown in a (values represent means±SEM, n=3, ***p<0.005 vs IL-2). (c) CD25⁺Foxp3⁻ Treg precursors sorted from Foxp3.eGFP murine CD4⁺SP thymocytes were labelled with Cell Trace Violet and cultured with IL-2 (top panel) or IL-2+OX40L (bottom panel) for 0–72 h, as described for a. Dot plots showing percentages of mature CD25⁺Foxp3⁺ Tregs converted from CD25⁺Foxp3⁻ Treg precursors. (d) Mature CD25⁺Foxp3⁺ Tregs were gated, and cell proliferation was measured by Cell Trace Violet dilution. Histograms show percentages of proliferating Tregs within converted CD25⁺Foxp3⁺ Tregs. (e) Bar graph showing percentages of resting (black) and proliferating (gray) CD25⁺Foxp3⁺ Tregs in culture (values represent means±SEM, n=3, ***p<0.005 vs IL-2). Treg, regulatory T cells.