Absence of AhR leads to attenuated aGVHD. (A) Spleens from 5 B6D2 recipients were pooled sorted for CD4⁺ and CD8⁺ T cells 14 days after transplant, and mRNA sequencing was performed as described in the supplemental Methods. (B) 4.0 × 10⁶ WT or AhR^−/− T cells were transferred along with 3.0 × 10⁶ T cell–depleted bone marrow (TCD BM) cells into lethally irradiated B6D2 recipients. Recipients were monitored for survival (B) and clinical score of GVHD (C). n = 10 for WT and AhR^−/− groups; n = 3 for BM only. Representative data of 2 independent experiments. Clinical score data were found to be significant starting from day 18 after transplant. (D) 5.0 × 10⁶ WT or AhR^−/− T cells were transferred along with 3.0 × 10⁶ TCD BM cells into lethally irradiated BALB.b recipients and monitored for survival (D) and clinical GVHD score (E). Pooled data from 2 independent experiments. n = 10 for WT, n = 11 for AhR^−/−, and n = 6 for BM only. *P < .05; **P < .001 by log-rank (Mantel-Cox) test for survival curves and 2-way analysis of variance for clinical scores comparing WT and AhR^−/−.