IL-18 and IL-18BP are upregulated and IL-18BP^−/−mice show a more pronounced IFN-γ signature than WT littermates after repeated CpG injections. (A) Il18, Il18bp, (B) Ifnγ, (C) Cxcl9, and (D) CIIta mRNA levels in the spleen (left panels) and liver (middle panels) are shown for naive (ctrl) or CpG-challenged (CpG) WT (n = 5-11) and IL-18BP^−/− (n = 5-12) female mice. Data are from 1 experiment at baseline and 2 pooled independent experiments after TLR9 stimulation. Plasma levels (right) of (A) free IL-18, (B) IFN-γ, and (C) CXCL9 are represented at baseline and on day 7 after CpG injections in WT (n = 11) and IL-18BP^−/− (n = 10) mice. Data were pooled from 2 independent experiments. The Mann-Whitney U test was used to compare WT and IL-18BP^−/− mice at 1 time point and to compare naive and CpG-challenged mice. The Wilcoxon signed-rank test was used to compare baseline and day 7 values within each genotype when data were paired.