Macrophage mannose receptor 1 (CD206) (MRC1)

The Macrophage mannose receptor 1 (MRC1), commonly referred to as CD206, is a 175 kDa type I transmembrane glycoprotein belonging to the C-type lectin family [UniProt P22897]. It is primarily expressed on macrophages, dendritic cells, and hepatic sinusoidal endothelial cells, serving as a key pattern recognition receptor in the innate immune system [NCBI Gene 4360]. The receptor facilitates the internalisation of glycoproteins and pathogens through the recognition of terminal mannose, fucose, or N-acetylglucosamine residues [Gazi & Martinez-Pomares, 2009, Immunobiology]. Beyond its role in host defense against bacteria, fungi, and viruses, MRC1 is involved in the homeostatic clearance of endogenous molecules like lysosomal enzymes and pituitary hormones [East & Isacke, 2002, Biochim Biophys Acta]. In oncology, CD206 is highly expressed on M2-polarized tumor-associated macrophages, which contribute to an immunosuppressive tumor microenvironment and promote metastasis [Scodeller et al., 2017, Sci Rep]. This high expression in specific macrophage populations makes it a valuable target for diagnostic imaging, as seen with the FDA-approved agent Technetium Tc 99m tilmanocept [FDA Label for Lymphoseek]. Current research also explores MRC1 for targeted drug delivery, aiming to deliver therapeutic payloads directly to macrophages in cancer, fibrosis, and infectious diseases.

Other names

Mannose receptorMannan receptorCD206C-type lectin domain family 13 member DCLEC13DMannose receptor C type 1

Binding to terminal mannose, fucose, or N-acetylglucosamine residues on ligands, facilitating receptor-mediated endocytosis and delivery to endolysosomal compartments for processing or degradation.