Angiogenic activity of human soluble intercellular adhesion molecule-1.

Serum levels of soluble intercellular adhesion molecule-1 (sICAM-1) are elevated in a number of pathological conditions associated with angiogenesis, including tumor growth. Because the increased levels of sICAM-1 suggested that it may be angiogenic, we tested the ability of sICAM-1 to promote angiogenesis. Human recombinant sICAM-1 stimulates chemokinetic endothelial cell migration, endothelial cell tube formation on Matrigel, and sprouting of aortic rings. sICAM-1 also mediates angiogenesis in the chick chorioallantoic membrane assay. Additionally, we found a Mr 49,000 molecule that binds to sICAM-1 that may be the surface ligand on endothelial cells. The evidence that sICAM-1 has angiogenic activity suggests a possible role linking inflammation and neovascularization. Furthermore, sICAM-1 may enhance tumor growth by promoting angiogenesis and escape from immunosurveillance.