(A–D) Antibody-mediated systemic blockade of IL-7R and GM-CSF affects clinical and intestinal GVHD manifestations in the complete MHC-mismatched model (C57Bl/6 into BALB/c). WT CD3⁺ T cell–recipient mice were given anti–IL-7R (αIL-7R) until day 15, either alone (gray line and triangles) or in combination with continuously administered anti–GM-CSF (αGM-CSF) (blue line and diamonds). As controls, WT donor T cells were continuously treated with isotype IgG antibody (red line and squares), or Batf^–/– donor T cells were transplanted alone without further treatment (black line and triangles). The clinical GVHD score (A), the colonoscopy score and representative endoscopic images (B), the histology score and representative histopathologic images of GVHD-associated colitis on day 28 (C), and the survival rates (D) are shown. Scale bars: 100 μm. Data from 2 independent experiments were pooled and include (A, B, and D) WT isotype IgG (n = 19), WT anti–IL-7R (n = 9), WT anti–GM-CSF/anti–IL-7R (n = 17), and untreated Batf^–/– (n = 4) mice; and (C) WT isotype IgG (n = 8), WT anti–IL-7R (n = 9), WT anti–GM-CSF/anti–IL-7R (n = 8), and untreated Batf^–/– (n = 4) mice. Shown are the relative frequencies (E) and absolute numbers (F) of cLP CD45.2⁺CD3⁺CD4⁺GM-CSF⁺ T cells, the absolute numbers of donor-derived cLP T cells (G), and CD44⁺CD62L^– (Tem) T cells (H) in CD45.2⁺CD3⁺CD4⁺ cLP T cells 28 days after GVHD induction (C57Bl/6 into BALB/c), which were treated with isotype IgG antibody, anti–IL-7R antibody alone, or in combination with anti–GM-CSF antibody, as described in A. A representative experiment of 2 experiments is shown and involved WT isotype IgG (n = 7), WT anti–IL-7R (n = 8), and WT anti–GM-CSF/anti–IL-7R (n = 7) mice. Data in A–E represent the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001, by 2-sided, unpaired Student’s t test (A) and 1-way ANOVA with Bonferroni’s multiple comparisons post test (B–H).