Systemic effects of IL1RAP blockade in Apoe^−/− mice. Immune cell composition was analysed in spleen, blood, and bone marrow from HCD-fed Apoe^−/− mice treated with anti-IL1RAP antibodies or isotype control (Ctrl IgG) (n = 14/group). (A) Quantification of counts of regulatory T cells (FoxP3⁺CD4⁺) per spleen. Splenocytes were stimulated with PMA/ionomycin and Brefeldin A for 4 h to analyse cytokine production and T cell subsets. Quantification of counts of IFN-γ-producing (B) CD4⁺ T cells and (C) CD8⁺ T cells per spleen. Quantification of (D) counts per spleen and (E) proportion of IL-17-producing CD4⁺ T cells. (F) Representative flow cytometry plot of circulating neutrophils. Quantification of neutrophils (CD11b⁺Ly6G⁺), Ly6C^low monocytes (CD11b⁺Ly6G⁻CD115⁺), and Ly6C^high monocytes, both as (G) counts per 100 μL of blood and (H) per cent of CD11b⁺ myeloid cells. (I) Representative flow cytometry plots of LT-HSC, ST-HSC, and MPP populations in bone marrow. Quantification of (J) numbers of live lineage-negative cells (P = 0.0283). Percentages and counts of (K and L) LT-HSCs (P = 0.0323), (M and N) ST-HSCs, (O and P) MPP3 cells (P = 0.024), and (Q and R) MPP4 cells (P = 0.0156). Bone marrow population percentages given as per cent of LSK cells, counts given as per leg (one tibia and one femur). Analysed with Student’s unpaired t-test or Mann–Whitney U test.