PECAM-1 (platelet endothelial cell adhesion molecule-1) is a newly characterized adhesion molecule that belongs to the immunoglobulin superfamily. PECAM-1 is a transmembrane glycoprotein with a molecular weight of approximately 130 kDa, depending on the degree of glycosylation. PECAM-1 is constitutively expressed on all vascular cells. It has also been found on platelets, monocytes, neutrophils, CD8+ T cells, bone marrow stem cells and transformed cell lines of the myeloid and megakaryocytic lineage. Interestingly, PECAM-1 was also detected on human, mouse and rat solid tumor lines [16]. Recent studies suggest a role for PECAM-1 in the inflammatory process and leukocyte-endothelial interaction. PECAM-1 appears to be able to interact both with itself (homophilic binding) and with other "non-PECAM-1" molecules (heterophilic binding). PECAM-1 is an early and sensitive marker for tumor-induced angiogenesis. Besides the membrane-bound form of PECAM-1 a soluble form of the molecule exists, which is 5-10 kDa smaller than cell-associated PECAM-1, and contains the cytoplasmic tail. Soluble PECAM-1 was detected in normal human plasma.

Applications

• Antibodies against PECAM-1 have been shown to exhibit a high degree of sensitivity and specificity for endothelial cells in normal, inflammatory and neoplastic tissue.
• PECAM-1 is a sensitive and specific marker for detection of melanoma-associated angiogenesis. Thus, PECAM-1 may be a useful marker for early detection of tumor metastasis.
• Compared to normal gut, there is a significant increase of PECAM-1-positive vessels in the mucosa of uninvolved ulcerative colitis [15].
• In gingivitis and periodontitis lesion the expression of PECAM-1 on mononuclear infiltrates increases significantly with increasing size of infiltrate.