Role of PECAM-1 in the adherence of PMN to hypoxic endothelial cells.

Hypoxia induces an increase in PMN adherence to endothelial cells for which an interaction between ICAM-1 and CD18/CD11b has been demonstrated. Since PECAM-1 has been shown to be involved in PMN transmigration through the endothelium and to increase the binding capacity of leukocyte CD18/CD11b, the role of this molecule in the hypoxia-induced PMN adherence was investigated. Hypoxia did not change the total surface expression of PECAM-1 on HUVEC and did not change the cell-cell border localization of this molecule as TNF-alpha did. In addition, blocking anti-PECAM-1 antibodies could not inhibit the increased adherence of unstimulated human PMN to hypoxia-incubated HUVEC while anti-ICAM-1 partially inhibited this process. These results indicate that PECAM-1 is probably not involved in the hypoxia-induced PMN adherence to endothelial cells.