Increases in cell-surface markers indicative of regulatory cells are seen following culture of normal splenocytes with mATG. C57BL/6 mouse splenocytes were cultured with 100 μg/mL mATG or rabbit IgG in the presence of 200 U/mL IL-2 for 5 days. Surface expression of CD25, GITR, CD62L, CD44, CD103, CD45RB, CTLA-4, and TGF-β was evaluated on total CD4⁺ (A) and CD8⁺ (C) T cells and all but CD25 expression was evaluated on CD4⁺CD25⁺ (B) and CD8⁺CD25⁺ (D) T cells as described in “Methods.” Data are means (± SD) of 3 replicates and from a representative of at least 6 separate experiments.