AhR signaling reprograms newly activated CD4+ T cells promoting combinatorial expression of regulatory genes to suppress murine GVHD [72 hr]

AhR activation during the first 3 days of an immune response is sufficient to reprogram CD4+ T cells, resulting in prevention of GVHD. To identify the early transciptional signature of AhR activation in CD4+ T cells, we performed analyses on mice treated with 2 different AhR ligands, TCDD and Cl-BBQ, in comparison with vehicle treated mice. Transcriptional responses were measured by global microarray analysis of donor alloresponding CD4+ T cells from spleen and lymph nodes. CFSE labeled splenocytes from C57Bl/6 mice were i.v. injected into B6D2F1 host mice (day 0). F1 mice (n=4-5) were treated i.p. with 15μg/kg TCDD on day 0, or vehicle or 10mg/kg Cl-BBQ on days 0, 1 and 2. Mice were sacrificed on day 3 and alloresponding CD4+ T cells (at least 2 cell divisions based on CFSE dilution) were isolated by pan-CD4 microbeads followed by FACS sorting.