Reduced Immunoregulatory CD31+ T Cells in Patients With Atherosclerotic Abdominal Aortic Aneurysm

BACKGROUND—Cell-mediated immunity is considered to contribute to the pathogenesis of abdominal aortic aneurysms (AAA). In particular, infiltrating macrophages and CD8 T lymphocytes participate in the destruction of the aortic wall extracellular matrix and smooth muscle cells. We surmise that these pathological events are controlled by circulating regulatory lymphocytes. METHODS AND RESULTS—Circulating CD4/CD31 cells were reduced in AAA patients (n=80, 8.9±0.6%) as compared with controls (n=69, 13.7±0.8%; P