Detection of B cells and proinflammatory cytokines in atherosclerotic plaques of hypercholesterolaemic apolipoprotein E knockout mice.

Atherosclerosis, the main lethal disease in the Western world, is associated with a cellular immune response in the arterial lesions and a humoral immune response directed towards oxidized lipoproteins, certain microbes and other antigens. The local immune response is dominated by macrophages and T cells, while to date, the role of B cells in lesions has been unclear. We analysed B-cell involvement in lesions using the apolipoprotein E knockout mouse, an experimental model that develops accelerated atherosclerosis when fed a lipid-rich diet. Both early fatty-streak-type lesions and full-blown atherosclerotic plaques of these mice contained CD22+ B cells. They accumulated predominantly in the base of lesions, where high expression levels of vascular cell adhesion molecule-1 (VCAM-1) were observed in other cells. Cells expressing interleukin-6 and tumour necrosis factor-alpha were also detected and IgM was abundant in this region. These data show that B cells participate in atherosclerosis in this experimental model; the data also suggest that these cells may accumulate through VCAM-1 expression by surrounding cells and may produce antibodies and proinflammatory cytokines. These factors are likely to be important in the pathogenesis of atherosclerosis.