CD31


Platelet endothelial cell adhesion molecule also known as cluster of differentiation 31 is a protein that in humans is encoded by the PECAM1 gene found on chromosome17q23.3. PECAM-1 plays a key role in removing aged neutrophils from the body.

Tissue distribution

CD31 is normally found on endothelial cells, platelets, macrophages and Kupffer cells, granulocytes, lymphocytes, megakaryocytes, and osteoclasts.
CD31 is also expressed in certain tumors, including epithelioid hemangioendothelioma, epithelioid sarcoma-like hemangioendothelioma, other vascular tumors, histiocytic malignancies, and plasmacytomas. It is rarely found in some sarcomas, such as Kaposi's sarcoma, and carcinomas.

Immunohistochemistry

In immunohistochemistry, CD31 is used primarily to demonstrate the presence of endothelial cells in histological tissue sections. This can help to evaluate the degree of tumor angiogenesis, which can imply a rapidly growing tumor. Malignant endothelial cells also commonly retain the antigen, so that CD31 immunohistochemistry can also be used to demonstrate both angiomas and angiosarcomas. It can also be demonstrated in small lymphocytic and lymphoblastic lymphomas, although more specific markers are available for these conditions.

Function

PECAM-1 is found on the surface of platelets, monocytes, neutrophils, and some types of T-cells, and makes up a large portion of endothelial cell intercellular junctions. The encoded protein is a member of the immunoglobulin superfamily and is likely involved in leukocyte transmigration, angiogenesis, and integrin activation. CD31 on endothelial cells binds to the CD38 receptor on natural killer cells for those cells to attach to the endothelium.