Peripheral deletion of alloreactive CD8 T cells. To monitor a well-defined population of alloreactive CD8 T cells during tolerance induction with ABT-737 and CsA, we adoptively transferred CBA recipients (H-2^k) with BM3.3 splenocytes (transgenic TCR specific for H-2K^b on all CD8 T cells) and subsequently treated with our irradiation-free conditioning protocol including ABT-737 (50 mg/kg/day), CsA (10 mg/kg/day) from day −3 to day 12, MR1 (2 mg), and 25 × 10⁶ fully BM cells from B6 donors (H-2^b). In a control group, BM cells were not administered (conditioning only). (A) Transgenic donor-reactive BM3.3 CD8 T cells (Ti98+) were reduced in both groups, but only in mice receiving the full protocol was a complete deletion achieved. Statistical comparison of the 2 groups: *P < .05; **P < .01; N = 5. (B-C) After rechallenging with donor antigens (10⁶ B6 splenocytes IV at day 37 after BMT), Ti98+ cells were readily detectable in the conditioning-only group, but had completely disappeared from the peripheral T-cell repertoire after exposure to the full protocol. **P < .01; N = 5 per group.