Irradiated B6D2F1 recipient mice were transplanted with 40 × 10⁶ 2C TCR⁺ admixed B6C3F1 splenocytes and 10 × 10⁶ WT TCD BM cells as described in Figure 3 (8% of CD8⁺ T cells were 2C TCR⁺) or with 40 × 10⁶ splenocytes and 10 × 10⁶ TCD BM from 2C TCR⁺ B6C3F1 donors. Mice received either vehicle or 25 mg/kg/d PTCy on days +3 and +4. On day +5, splenocytes from these mice were flow cytometrically sorted to isolate viable 2C TCR⁺ T cells (LIVE/DEAD^–CD8⁺Vβ8.1/8.2⁺1B2⁺). 0.5 × 10⁶ 2C TCR⁺ T cells from mice that had received 2C/WT admixed grafts or 1 × 10⁶ 2C TCR⁺ T cells from mice that had received only 2C splenocytes were combined with 5 × 10⁶ 2C TCD BM cells (BM from new 2C donors that was flow cytometrically depleted of Thy1.2⁺ cells). These grafts then were transplanted into new, irradiated (10.5 Gy), thymectomized, B6D2F1 recipients. These recipients did not receive any posttransplant treatment (i.e., no PTCy or vehicle on days +3/+4). Combined results from mice receiving 2C TCR⁺ T cells from 2C only grafts (n = 5 vehicle treated, n = 5 PTCy treated) or from 2C/WT admixed grafts (n = 5 vehicle treated, n = 4 PTCy treated) are shown as are data for 5 mice receiving TCD BM only. Results of each individual experiment are shown in Supplemental Figure 15. (A) Although the GVHD induced was not fatal for either treatment group, mice receiving PTCy-treated cells had superior weights and clinical scores compared with mice receiving vehicle-treated cells. AUC values were compared using Wilcoxon’s rank sum test. (B) These differences were seen even though similar numbers of 2C TCR⁺ T cells persisted in the liver at day +150 in mice receiving vehicle-treated or PTCy-treated cells.