Figure 4

Retrovirus-mediated transduction of FoxP3 and Bcl-xL sustains survival of regulatory T cells in vivo. Naive CD4⁺ T cells from OT-II T-cell receptor transgenic mice were stimulated with peptide/antigen-presenting cells. On day 2/3, T cells were transduced with retroviral vectors expressing green fluorescent protein (GFP), GFP with Bcl-xL, GFP with FoxP3, or GFP with Bcl-xL and FoxP3. On day 6 of primary culture, 2 × 10⁶ GFP⁺ CD4⁺ T cells were sorted and adoptively transferred into naive recipient mice that were subsequently challenged intraperitoneally with whole ovalbumin (OVA) protein (100 μg) in phosphate-buffered saline (PBS) (filled bars) or with PBS alone (open bars). On days 7 and 14, GFP⁺ CD4⁺ T cells were enumerated from pooled lymph nodes and spleen. Data are mean number of GFP⁺ CD4⁺ ± standard error of the mean from four individual mice and representative of three independent experiments (*P <0.05, Student unpaired t test).