The same study reports an inverse correlation between the expression level of CXCR4 on B1 cells and coronary artery plaque burden and necrosis [108] and shows in Apoe−/− mice with a B-cell-specific knockout of CXCR4 a decreased IgM production in the BM as well as a reduction in IgM plasma levels, associated with enhanced aortic atherosclerosis lesion size (Fig. 3). Here, CXCR4 is linked to aortic atherosclerosis.