Tolerogenic anti–IL-2 mAb (JES6-1A12) preserves CD8⁺ Tmp and functional effectors that mediate GVL activity in lymphoid tissues more effectively than TAC. Lethally irradiated WT BALB/c recipients were given splenocytes (2.5 × 10⁶) and TCD-BM cells (2.5 × 10⁶) from C57BL/6 donors. Recipients were given a total of 4 i.p. injections of anti–IL-2 mAb (JES6-1A12) (500 µg/mouse) at days 0, 2, 4, and 6 after HCT, or once-daily i.p. injections of TAC (0.75 mg/kg) at days 0 to 6 after HCT. On day 7 after HCT, mesenteric lymph node (MLN), spleen (SPL), liver, and colon were harvested for analysis. (A) Representative pattern of gating strategy in recipients given anti–IL-2 treatment. (B) Representative flow cytometry pattern showing the expression of granzyme B and CD107a on CD8⁺ T cells and percentage of CD107a⁺granzymeB⁺ CD8⁺ T cells in the SPL from IL-2 mAb– or TAC-treated recipients are shown; n = 4 to 6, combined from 2 experiments. (C-H) Percentage of Tmp (CD39^–Ly108⁺), Teff (CD39⁺Ly108⁺), and Tex (CD39⁺Ly108^–) among donor CD8⁺ T cells in MLN, SPL, liver, and colon of WT recipients treated with anti–IL-2 mAb (JES6-1A12), TAC, or control IgG; n = 4-6 per group. (I) Percentage of granzymeB⁺CD107a⁺ CD8⁺T, IFN-γ⁺ CD8⁺T cells and mean fluorescence intensity (MFI) of perforin among Teff, Tex, and Tmp in SPL and MLN of WT recipients treated with anti–IL-2 mAb (JES6-1A12). n = 4-6 per group. (J-K) Expression of T-bet, CD127, 5-bromo-2′-deoxyuridine (BrdU), and Tim3 on Teff, Tex, and Tmp in SPL and MLN of WT recipients treated with anti–IL-2 mAb (JES6-1A12). n = 4 to 6 per group. (L) Percentage of IL-2⁺ CD4⁺ T cells in SPL and MLN of WT recipients treated with anti–IL-2 mAb (JES6-1A12) or TAC. n = 4 per group. P values were calculated by unpaired two-tailed Student t tests, one-way analysis of variance, or two-way analysis of variance. *P < .05, **P < .01, ***P < .001, ****P < .0001.