NIMA-induced allotolerance requires CD4⁺CD25⁺ T cells. Lethally irradiated B6D2F1 mice received transplants with 5 × 10⁶ TCD BM from control B6 mice together with 1 × 10⁶ CD4⁺ T cells from either a NIMA-exposed B6 or control B6 donor. (A) Survival rates of syngeneic BMT (, n = 6), allogeneic BMT from a control donor (○, n = 11), and allogeneic BMT from a NIMA-exposed B6 (•, n = 11) are shown. Data from 2 similar experiments were combined. (B) CD25⁺ T cells were depleted from CD4⁺ T cells of a NIMA-exposed or NIMA-nonexposed B6 donor. Lethally irradiated B6D2F1 mice were injected with 5 × 10⁶ TCD BM from a control B6 mouse together with 1 × 10⁶ CD25-depleted CD4⁺ T cells from a NIMA donor or a control donor. Survival rates of syngeneic BMT (•, n = 6), allogeneic BMT from a control donor (○, n = 11), and allogeneic BMT from a NIMA-exposed B6 (•, n = 11) are shown. Data from 2 similar experiments were combined. ^**P < .005 versus controls.