Mannose-specific oligosaccharide recognition by mononuclear phagocytes.

Glycoproteins terminating in mannose are recognized by receptors on macrophages. The mannose receptor is expressed by a variety of macrophages but expression is closely regulated. Activated macrophages, for example, express little mannose receptor activity. Kinetic and fractionation experiments suggest that cell surface mannose receptors recycle to and from an acidic, pre-lysosomal compartment. Preliminary evidence suggests that the mannose receptor is a large polypeptide and that it is structurally related to the mannose binding protein found in serum. The mannose receptor may, among other possibilities, regulate the extracellular levels of lysosomal hydrolases.