Common β-chain signaling drives alloantigen presentation in the GI tract. (A-E) BALB/c mice were transplanted with TCD BM from B6.WT or B6.common β-chain^−/− mice and B6.WT T cells. On day 12 B6.TEa^luc+ cells were injected, and 3 days later, DC subsets and TEa T-cell expansion were analyzed. The absolute numbers of total donor DC (A), the frequency of CCR7⁺ (B), and the frequency of YAe⁺ in total donor DC (C) from spleen, mLN, and peripheral lymph node are shown. (D) The absolute number of YAe⁺ donor DC within mLN. (A-D) The data are combined from 2 replicate experiments (n = 11-13 per group). (E) Representative images (left) and quantification (right) of bioluminescence signals as a measure of alloantigen presentation and T-cell priming. The data are combined from 3 replicate experiments (n = 18-20 per group). (F) BALB/c mice were transplanted with B6.WT or B6.common β-chain^−/− TCD BM and 2 × 10⁶ sort purified CD4⁺ B6.TEa T cells. Representative hematoxylin and eosin images (left) and semiquantitative histopathology scores of colon (right) at day 14 after BMT (n = 5-6 per group). (G) BALB/c mice were transplanted with TCD BM from B6.CD11c^luc+ reporter mice and B6.WT or B6.GM-CSF^−/− T cells. On day 18 donor DC (CD11c^luc+) were quantified (n = 4-5 per group). (H-J) BALB/c mice were transplanted with TCD BM from B6.WT mice and B6.WT or B6.GM-CSF^−/− T cells. On day 12 TEa^luc+ cells were injected, and 3 days later, DC subsets and TEa expansion were analyzed. Representative fluorescence-activated cell sorter plots of DC subset proportions (H), absolute numbers of YAe⁺ donor DC subsets in mLN (I), and representative images (left) and quantification (right) of bioluminescence signals as a measure of alloantigen presentation and T-cell priming (J). The data are combined from 2 replicate experiments (n = 8-9 per group). Statistical analysis by unpaired Student t test with Welch’s correction (mean ± SEM). *P < .05; **P < .01; ***P < .001; ****P < .0001.