Systemic upregulation of leukocyte integrins in response to lower body ischemia-reperfusion during abdominal aortic aneurysm repair

Ischemia and reperfusion in myocardial infarction and stroke are associated with upregulation of leukocyte adhesion molecules, which contributes to tissue injury by facilitating leukocyte adhesion and infiltration in the affected tissues. Surgical repair of the abdominal aortic aneurysm involves clamping and declamping of the aorta, which necessarily results in ischemia and reperfusion of the lower half of the body. Given the large volume of the affected tissues and unimpeded venous return during reperfusion, we hypothesized that the procedure may result in upregulation of leukocyte integrins in the systemic circulation. To test this hypothesis, we studied neutrophil and monocyte surface densities of CD11b and CD18 in patients undergoing elective infrarenal abdominal aortic aneurysm repair. Serial blood samples were collected from the radial artery and femoral vein during the operation and leukocyte CD11b and CD18 surface densities were quantified by flow cytometry. Following reperfusion, CD11b expression in neutrophils and monocytes increased significantly in femoral venous and arterial blood. The mean time to peak expression of CD11 b in neutrophils and monocytes during reperfusion was 34.4 and 31.4 minutes in venous and 38.5 and 36.4 minutes in arterial blood, respectively. Similar rises in CD18 expression on neutrophils and monocytes were observed in venous and arterial blood. The mean time to peak expression of CD18 in neutrophils and monocytes during reperfusion was 34.0 and 40.0 minutes in venous and 47.5 and 50.0 minutes in arterial blood, respectively.