Nod2 signaling maintains IELs via recognition of gut microbiota. (A) Bacterial 16S DNA were determined by quantitative PCR and normalized to total mouse genomic DNA in the same pellets of mice treated with antibiotics (Ab) for 6 wk. (B) Quantification of total numbers of small intestinal IELs, liver lymphocytes, splenocytes, and thymocytes in antibiotic (Ab)-treated and control mice (Mock). **, P < 0.01. (C) Quantification of total numbers of small intestinal IELs in mice treated with antibiotics alone (Ab) or in the presence of MDP (Ab + MDP) or iEDAP (Ab + iEDAP). Horizontal bars indicate the mean. *, P < 0.05. (D and E) The percentages (D) or absolute numbers (E) of the indicated IEL subsets in the small intestine of mice treated with antibiotics alone (Ab) or in the presence of MDP (Ab + MDP) or iEDAP (Ab + iEDAP) are shown. *, P < 0.05; **, P < 0.01. At least 15 mice per group. (F) Mice were treated with antibiotics (Ab) with or without the presence of MDP, and the splenocytes were stained as indicated. Numbers in the dot plots indicate the percentage of cells represented in the quadrant. Three to five mice per group. Representative of three experiments. Error bars indicate SEM.