Treg-cell suppressor function is maintained when CD153 (CD30L) is blocked in the late phase after transplantation. Recipients underwent transplantation as described in “Materials and methods” for the FVB/N→Balb/c combination. To block the CD30/CD153 interaction in the late phase of Treg-cell expansion, the Abs (each 0.1 mg) were injected on days 4, 6, 8, and 10. Data from 3 independent experiments are combined. (A) TCD-BM (▵, n = 15), with Tconv cells (□, n = 15), with Tconv cells and Treg cells and isotype IgG (○, n = 12), and with Tconv cells and Treg cells and anti-CD153 blocking Ab (•, n = 12). Signal intensity is not significantly different in animals receiving Tconv cells and Treg cells and anti-CD153 blocking Ab compared with isotype IgG (• versus ○, NS). Error bars indicate SD from the mean. (B) TCD-BM (▵, n = 15), with Tconv cells (□, n = 15), with Tconv cells and Treg cells and isotype IgG (○, n = 12), and with Tconv cells and Treg cells and late anti-CD153 blocking Ab (•, n = 12).