AhR^−/− mice have a deficiency in CD49a⁺TRAIL⁺DX5⁻ liver-resident NK cells. (A) NK (NK1.1⁺CD3⁻) cell percentages (left) and expression of CD27 and CD11b on NK cells (right) from the spleen (top) and BM (bottom) of AhR^+/+ or AhR^−/− mice. (B) Percentage, cell number, and representative plots of CD49a⁺DX5⁻ (left) and TRAIL⁺ (right) liver NK cells from AhR^+/+ or AhR^+/− versus AhR^−/− mice. SSC, side scatter. (C) Representative plots of TRAIL⁺ CD3⁻NK1.1⁺ NK cells from the liver of AhR^+/+ and AHR^−/− mice at 4 wk. (D) CD49a⁺DX5⁻ NK cells, sorted from the liver of AhR^+/− and AhR^−/− mice, were assessed for CXCR6 mRNA expression by quantitative RT-PCR, normalized to HPRT, and shown relative to AhR^+/− cells. (E) Expression of CD27 and CD11b on CD49a⁺DX5⁻ liver NK cells from AhR^+/+ (circles) and AhR^−/− (triangles) mice. (F) Representative histograms of eomes (bottom) and T-bet (top) staining in TRAIL⁺ (left) and TRAIL⁻ (right) liver NK cells of AhR^+/+ (continuous line) and AhR^−/− mice (dashed line), as well as an isotype control (shaded). (G) Sublethally irradiated CD45.1⁺ recipient host mice were reconstituted i.v. with an equal mixture of CD45.1⁺ WT and CD45.2⁺ AhR^+/− or AhR^−/− fetal liver cells. (Top) At 2 mo, mice received three i.v. injections of 3 µg FICZ over the course of 1 wk before analysis of liver NK cells. The ratio of CD45.2⁺ to CD45.1⁺ cells in TRAIL⁺ liver NK cells from recipients of AhR^+/− versus AhR^−/− fetal liver cells is shown. (Bottom) Representative plots of CD45.2 and CD45.1 staining on TRAIL⁺ liver NK cells. Scatter plots are from at least two independent experiments, and n = 4–11 mice per group. All contour plots are representative of at least two independent experiments. Data are shown as mean ± SEM. **, P < 0.01; ***, P < 0.001 (unpaired Student’s t test).