IL-1β drives innate immune colitis. 129SvEv Rag2^−/− mice were infected with H. hepaticus, treated weekly with 1 mg of αIL-1β antibody or isotype control (i.p.), and sacrificed after 8 wk of infection. (A) Scores of colon inflammation. Each symbol represents an individual mouse, and data are pooled from four independent experiments. Bars represent the mean histological score for each group. (B) Spleen weights and splenocyte numbers. (C) Representative photomicrographs of mid-colon and liver sections. Bars, 200 µm. (D) Colonic lamina propria leukocytes were isolated from the described mice groups and cytokine secretion after overnight culture in complete media was determined. Data are shown as mean ± SEM from 3 pooled independent experiments (n = 9–16). (E) Cytokine concentration in blood serum (mean ± SEM, n = 6–10 from 2 pooled independent experiments). ND, not detectable; *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001.