(A) B6 mice were transplanted with Balb/c skin grafts, and were injected with a short course of either 1 mg/kg H57-597 mAb or its isotype Ab on days 0, 1, 3, 7 and 11 post-grafting. The graph shows the percentage graft survival after transplantation. (B) B6 mice were pre-sensitized against Balb/c antigens by transplantation with Balb/c-donor skin grafts. 2-3 weeks after the skin transplantation, these recipient mice were then transplanted with Balb/c heart allografts, and injected with a short course of either 1 mg/kg H57-597 mAb or its isotype Ab on days 0, 1, 3, 7 and 11 post-heart grafting. The graph shows percentage survival of heart grafts in the sensitized mice. (C–E) Splenocytes and lymph nodes were isolated at indicated days after secondary heart transplantion from skin-sensitized, recipient mice treated with H57-597 mAb or isotype Ab. The figure shows the dot plots (C) and bar graphs (D) representative of the frequencies of FoxP3+ cells among the CD4 T-cell populations. (E) The figure shows the bar graphs representative of the number of CD4 (left panel) or CD8 (right panel) cells in spleens of the above mice.