Anti–third-party Tcms can be used with decreased irradiation dose when coadministered with low-dose rapamycin. Sublethally irradiated (4.5Gy TBI) Balb/c (H-2^d) mice were transplanted with 20 × 10⁶ C57BL/6-nude (H-2^b) BM cells with or without: 5 × 10⁶ allogeneic C57BL/6 Tcm (H-2^b; ▵ and ) or 5 × 10⁶ CB6 F1 Tcm (H-2^bd; ●). The indicated groups received subcutaneous injections of 0.5 mg/kg bw rapamycin during 5 days (days −1 to +4). Percentage of donor cells in peripheral blood, analyzed 90 days after transplant by FACS using anti-donor (H-2K^b) antibodies is presented. Data represents results of at least 2 independent experiments (*P < .05; ***P < .001).