Blocking IL-1β impairs the accumulation of proinflammatory CD11b⁺Gr1^Hi granulocytes in the inflamed colon. 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) Leukocytes were isolated from the colon and spleen, and the frequency of CD45⁺CD11b⁺Gr1^Hi cells was assessed by flow cytometry (mean ± SEM from 3 pooled independent experiments, n = 9–16). (B) Representative FACS plots from the data presented in A (gated on CD45⁺ cells). (C) Colon chemokine expression as evaluated by qRT-PCR on total colon homogenates (mean ± SEM, n = 6–12 from 2 pooled independent experiments). *, P < 0.05; **, P < 0.01; ***, P < 0.001.