The numbers of CD4⁺ Foxp3⁺ T cells were comparable between [WT → C3H] and [H2-Ab1^−/− → C3H] mice. Cells isolated from the thymus and spleen from [WT → C3H] and [H2-Ab1^−/− → C3H] mice were stained for CD4 and Foxp3 mAbs. (A) The dot plots show the 2-color staining pattern for CD4-FITC and Foxp3-PE on CD4 single-positive thymocytes and splenocytes 5 weeks after BMT. (B) The numbers of CD4⁺ Foxp3⁺ T cells on the CD4 single-positive thymocytes and splenocytes from [WT → C3H] or [H2-Ab1^−/− → C3H] mice were enumerated 5 and 8 weeks after BMT (n = 3 per group). (C) C3H mice were irradiated and underwent transplantation with TCD-BM from either control WT or H2-Ab1^−/− B6 donors. After BMT, mice were injected with anti-CD25 mAbs or control Abs. Weight changes as the mean ± SE after BMT are shown. ○, [WT → C3H], n = 4; •, control [H2-Ab1^−/− → C3H], n = 6; □, [H2-Ab1^−/− → C3H] treated with anti-CD25 mAbs, n = 6. *P < .05.