Role of the beta2-integrins and immunoglobulin superfamily members in myocardial ischemia-reperfusion.

Leukocytes play a key role in the inflammatory processes such as ischemia-reperfusion of the coronary vasculature. Their interaction with the endothelium is closely regulated. The first step in the process is the rolling of leukocytes (eg, neutrophils) along the microvascular endothelium. This is regulated by the selectin family of cell adhesion molecules, primarily P-selectin. The next step in the inflammatory cascade is the firm adhesion of these neutrophils to the activated or dysfunctional endothelium. This process is governed by the beta2-integrins on the leukocytes (eg, CD11/CD18) and by ICAM-1 on the activated endothelium. CD11/CD18 is a beta2-integrin, and ICAM-1 is a member of the immunoglobulin superfamily of adhesion glycoproteins. By their interaction, neutrophils flatten out and adhere to the vascular endothelium. Many of these adhered neutrophils are then able to transmigrate across the endothelium to the site of the inflammation (ie, the focus of the ischemia-reperfusion). This transmigration is primarily stimulated by PECAM-1, another member of the immunoglobulin superfamily. These processes are discussed in this brief review.