Antibody to CD 18 exerts endothelial and cardiac protective effects in myocardial ischemia and reperfusion

We studied the effects of MAbR15.7, an antibody directed against the common,8-chain (CD-18) of a family of neutrophil adherence glycoproteins, on endothelial dysfunction and myocardial injury in a model of myocardial ischemia and reperfusion in cats. Pentobarbital-anesthetized cats were subjected to 1.5 h occlusion of the left anterior descending coronary artery (LAD) and 4.5 h of reperfusion. MI + R resulted in severe myocardial injury and endothelial dysfunction, including significant elevation of plasma creatine kinase (CK) activity, marked myocardial necrosis, high cardiac myeloperoxidase (MPO) activity in ischemic cardiac tissue, and loss of response of LAD coronary rings to the endothelium-dependent vasodilators, acetylcholine (ACh) and A-23187. In contrast, MAbR15.7-treated cats exhibited a lower plasma CK activity at every time point observed after 2 h, a reduced area of cardiac necrosis (2±1 vs. 30.8±2.5 % of area-at-risk, P < 0.001), lower MPO activity in the ischemic region (P < 0.01), and significantly preserved vasorelaxant responses of LAD coronary rings to endotheliumdependent vasodilators, ACh (P < 0.001), and A-23187 (P < 0.001). These results indicate that myocardial ischemia and reperfusion induces significant myocardial injury and endothelial dysfunction in the cat involving a CD18-dependent neutrophil adherence mechanism. Inhibition of neutrophil adherence to the endothelium exerts significant protective effects in this model of reperfusion injury. (J. Clin. Invest. 1991. 88:1237-1243.) Key words: endothelial dysfunction * endothelium derived relaxing factor * neutrophil adhesive proteins * myeloperoxidase * coronary artery rings * acetylcholin