Background：CD206, also known as mannose receptor （MR）, is a 175 kD type I membrane protein. It is a pattern recognition receptor （PRR） belonging to the C-type lectin superfamily. MR is expressed on macrophages, dendritic cells, Langerhans cells, and hepatic or lymphatic endothelial cells. MR recognizes a range of microbial carbohydrates bearing mannose, fucose, or N-acetyl glucosamine through its C-type lectin-like carbohydrate recognition domains, sulfated carbohydrate antigens through its cysteine-rich domain, and collagens through its fibronectin type II domain. MR mediates endocytosis and phagocytosis as well as activation of macrophages and antigen presentation. It plays an important role in host defense and provides a link between innate and adaptive immunity. Recently, MR on lymphatic endothelial cells was found to be involved in leukocyte trafficking and a contributor to the metastatic behavior of cancer cells. It suggests that MR may be a potential target in controlling inflammation and cancer metastasis by targeting the lymphatic vasculature.
