Figure 2

Retrovirus-mediated transduction of FoxP3 and Bcl-xL promotes survival of regulatory T cells in vitro. Naive CD4⁺ T cells from C57BL/6J mice were stimulated with anti-CD3 plus anti-CD28 antibodies, transduced on days 2/3 with retroviral vectors expressing green fluorescent protein (GFP), GFP with FoxP3, or GFP with Bcl-xL and FoxP3, and then recultured without any further stimulation. (a) Live CD4⁺ GFP⁺ T cells were visualized by flow cytometry on day 6 of culture. Data are representative of three independent experiments. (b) GFP⁺ T-cell recovery was normalized to take into account differences in initial transduction efficiency between cultures. Numbers of GFP⁺ cells present on day 2 were assigned a value of 100%, and numbers surviving on days 4, 6, and 8 were used to calculate the percentage recovery relative to day 2. Data represent the mean percentage change ± standard deviation from three separate experiments (*P <0.05, Student unpaired t test). (c) CD25 expression on day 4 of primary culture was analyzed by flow cytometry after gating on live GFP⁺ CD4⁺ T cells. Data are representative of three independent experiments.