Fig. 2: Transplanted donor Treg migrate into GvHD target organs and alleviate transplant-associated complications in a murine MHC-disparate BMT model.

a Schematic overview of the experimental GvHD model and its controls. Left panel: GvHD in BALB/c recipients is induced by MACS-purified conventional CD4⁺CD25⁻ donor T cells (Tconv; 1 × 10⁶ cells/recipient) transferred together with T cell-depleted (TCD) BM (2.5 × 10⁶ cells/recipient), both from congenic CD45.1⁺ C57BL/6 mice. FACS-purified and in vitro expanded donor Treg from CD45.2⁺ Foxp3^gfp mice are additionally given on d0 at a 1:1 ratio with Tconv for GvHD prevention (prophylaxis). Middle panel: the “no GvHD” transplantation control, which corresponds to the GvHD setting, but without transfer of Tconv. Right panel: organ resident C57BL/6 Treg serving as homeostatic control (no BMT). In both BMT settings, Treg (and Tconv) cells were re-isolated from the indicated organs 7 days after transfer for further analyses. b Bar plots showing absolute Treg cell numbers in the respective organs of C57BL/6 donor mice (noBMT) or absolute donor Treg cell numbers in transplanted BALB/c recipients that received allo or polyTreg together with TCD BM (no GvHD) or TCD BM and additional Tconv (GVHD prophylaxis). c Bar plots showing absolute Tconv cell numbers in the respective organs of “noBMT” donor mice or absolute numbers of donor Tconv in recipients transplanted with TCD BM and Tconv in the presence of allo or polyTreg (prophylaxis) or without Treg (no Treg, GvHD). b, c Bars represent mean values ± SEM and dots represent data from individual recipients (numbers of independent recipient animals are indicated). Significant differences between BMT groups are indicated above bars. (One-way ANOVA with Tukey’s post hoc test, except: BM and mLN in (b), two-tailed t-test; liver in (b), Kruskal–Wallis test with Dunn’s post hoc test). d Survival of the indicated BMT recipient groups. Significant differences in survival are indicated on the right (Log rank test with Bonferroni correction). e Corresponding clinical GvHD scores for animals in (d). Data are presented as mean values ± SEM. Significant differences between treatment groups at individual data points are indicated on the top (one-way ANOVA with Tukey’s post hoc test). b–e *p < 0.05, **p < 0.01, ***p < 0.001. b–e Source data and exact p values (b, c, e) are provided as a Source Data file.