IL1RAP is present in atherosclerotic plaques of Apoe^−/− mice. Immunohistochemical staining of IL1RAP and quantification of IL1RAP-expressing cells (per cent of total nucleated cells) in the aortic root of (A and B) wild-type (C57Bl/6, n = 7) and (C and D) hyperlipidaemic Apoe^−/− mice (n = 6). The media layer is outlined by the dashed line. Flow cytometric analysis was performed to identify IL1RAP expression on leucocytes in the blood and digested atherosclerotic aortas of hyperlipidaemic Apoe^−/− mice (n = 7). (E) Representative histograms of IL1RAP expression on monocytes (CD115⁺Ly6G⁻CD11b⁺), neutrophils (Ly6G⁺CD11b⁺), and T cells (CD11b⁻TCRβ⁺) in the blood and (F) quantification of IL1RAP MFI (ΔMFI) on leucocytes in the blood. (G) Representative histograms of IL1RAP expression on macrophages, neutrophils, and T cells in digested aorta and (H) quantification of IL1RAP (ΔMFI) on leucocytes in digested aorta. ΔMFI defined as the difference in MFI in each cell population between anti-IL1RAP and isotype antibody staining. Analysed with (B) Student’s unpaired t-test and (D) Kruskal–Wallis test with Dunn’s multiple comparisons test.