Expression and function of other IL-1R family members in IL-33 KO and ST2 KO BMDC. (A) Schematic representation of the IL-1R gene cluster, including the ST2 gene Ilrl1, on mouse chromosome 1. Mb, megabase pairs. (B) Expression levels of mRNA for different IL-1R family members encoded in this locus in WT, IL-33 KO and ST2 KO BMDC. Transcript levels were normalized to Gapdh expression and expressed relative to values obtained in WT cells, which were arbitrarily set to 1. Data shown represent the mean ± SEM of three determinations in independent cultures derived from IL-33 KO mice (grey columns), ST2 KO mice (black columns) or WT C57BL/6 mice (open columns). &P < 0.05 ST2KO vs. IL-33 KO cells, ANOVA. (C) Function of different IL-1R family members in cultured WT, IL-33 KO and ST2 KO BMDC. Induction of IL-6 production in response to 72 h of stimulation with different IL-1 family cytokines, namely IL-36, IL-1β, IL-18 and IL-33 (100 ng/ml) was monitored in BMDC derived from IL-33 KO mice (grey columns), ST2 KO mice (black columns) or WT C57BL/6 mice (open columns). Lipopolysaccharide (LPS) (100 ng/ml) stimulation was used as an unrelated positive control. Results are shown as mean ± SEM of values obtained in three independent cultures. *P < 0.05 vs. WT cells; &P < 0.05 ST2KO vs. IL-33 KO cells, ANOVA. BMDC, bone marrow-derived dendritic cell; KO, knockout; WT, wild-type.