mATG does not induce Foxp3 expression in vitro. C57BL/6 mouse splenocytes were cultured with 100 μg/mL mATG or rabbit IgG in the presence of 200 U/mL IL-2, and 5 days following initiation of culture cells were evaluated for Foxp3 expression by flow cytometric analysis (A) or quantitative RT-PCR (B) as described in “Methods.” Foxp3 mRNA levels were normalized to CD3 mRNA in each sample. The flow cytometric data are representative of at least 6 experiments and the mRNA analysis was performed once.