Background：CD31 is a 130-140 kD glycoprotein, also known as platelet endothelial cell adhesion molecule （PECAM-1） and EndoCAM. It is a member of the Ig superfamily, expressed on endothelial cells, platelets, granulocytes, monocytes/macrophages, dendritic cells, and T and B cell subsets, and is critical for cell-cell interactions. The primary ligands for CD31 have been reported to be CD38 and the vitronectin receptor （av b3 integrin, CD51/CD61）. Other reported functions of CD31 are neutrophil emigration to sites of inflammation and angiogenesis.
