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.