Platelet-endothelial cell adhesion molecule-1 (PECAM-1)-deficient mice demonstrate a transient and cytokine-specific role for PECAM-1 in leukocyte migration through the perivascular basement membrane

Studies with neutralizing antibodies have indicated roles for platelet-endothelial cell adhesion molecule-1 (PECAM-1) in leukocyte migration through the endothelium and the perivascular basement membrane. Because some of these findings have been contentious, this study aimed to explore the role of PECAM-1 in leukocyte migration by analyzing leukocyte responses in interleukin 1 beta (IL-1 beta)- and tumor necrosis factor-alpha (TNF alpha)-activated cremasteric venules of PECAM-1-deficient mice using intravital and electron microscopy, Although no differences in levels of leukocyte rolling flux or firm adhesion were observed, a delay in leukocyte transmigration in response to IL-1 beta, but not TNF alpha, was detected in PECAM-1-deficient mice. Electron microscopy indicated that this delay occurred at the level of perivascular basement membrane. To address the cytokine specificity of PECAM-1 dependence, in vitro experiments demonstrated that TNF alpha, but not IL-1 beta, could induce rapid adhesion of murine neutrophils to protein-coated surfaces, suggesting that TNF alpha elicited leukocyte transmigration In wild-type mice via direct stimulation of leukocytes. In summary, the results suggest a regulatory role for PECAM-1 in leukocyte migration through the perivascular basement membrane, a role that appears to be cytokine-specific and associated with the ability of the cytokine to stimulate rapid neutrophil adhesion. (Blood. 2001;97:1854-1860) (C) 2001 by The American Society of Hematology.