Leukocyte integrin expression in patients undergoing cardiopulmonary bypass

Background. The recruitment of leukocytes to vascular endothelium is contro lled by adhesion events mediated through the beta(2) integrins, whereas the response of extravasated leukocytes within the tissues is controlled throu gh the beta(1) integrins. Although cardiopulmonary bypass (CPB) has been sh own to be associated with a systemic inflammatory response and elevated lev els of beta(2) integrins on leukocytes, its effect on the beta(1) integrins is not known. This study investigated the effect of the protease inhibitor aprotinin on the expression of the beta(1) and beta(2) integrins on circul ating leukocytes in patients undergoing CPB. Methods. Patients undergoing primary elective coronary artery bypass grafti ng were randomized into full-dose aprotinin or placebo groups. Blood sample s were obtained at nine time points preoperatively, intraoperatively, acid up to 6 days postoperatively. The surface expression of the beta(1) integri ns VLA-1, -3, -4, -5, and -6 and of the beta(2) integrins CD11a/CD18, CD11b /CD18, and CD11c/CD18 was measured by flow cytometry on gated neutrophil an d monocyte subpopulations in whole blood. Results. Expression of the beta(1) integrins was not significantly altered during the study period and, therefore, aprotinin had no effect on the expr ession of these molecules. Of the beta(2) integrins, CD11b/CD18 expression was significantly increased on neutrophils at 15 minutes after onset of CPB in the placebo group (p < 0.01) but not in the aprotinin group. Conclusions. This study showed that expression of the p, integrins on neutr ophils and monocytes did not alter during the first 6 days after CPB. Expre ssion of the beta(2) integrin CD11b/CD18 increased significantly on neutrop hils during CPB in control patients but not in patients treated with full-d ose aprotinin. (C) 2000 by The Society of Thoracic Surgeons.