The mannose receptor, a bi-functional lectin with roles in homeostasis and immunity

The mannose receptor (MR) is a unique bi-functional molecule with two lectin activities. Its N-terminal cysteine-rich (CR) domain exclusively recognises endogenous acidic glycans, while its C-type-lectin domains (CRDs) bind carbohydrates decorating some microbial surfaces, as well as some secreted endogenous glycoproteins that are cleared through this receptor. In this review we aim to provide an update on some aspects of MR biology with special emphasis on its role in clearance (when expressed in tissue macrophages (M) and sinusoidal endothelia), antigen delivery (as cell associated form on dendritic cells (DCs), or through targeting of its soluble form to lymphoid organs) and cell adhesion (when expressed by lymphatic endothelia).