THE MANNOSE RECEPTOR FUNCTIONS AS A HIGH-CAPACITY AND BROAD-SPECIFICITY ANTIGEN RECEPTOR IN HUMAN DENDRITIC CELLS

Dendritic cells, in contrast to B lymphocytes, must be able to efficie ntly internalize a diverse array of antigens for processing and loadin g onto major histocompatibility complex (MHC) class II molecules. Here we characterize the mannose receptor pathway in dendritic cells and s how that mannose receptor-mediated uptake of antigens results in a sim ilar to 100-fold more efficient presentation to T cells, as compared t o antigens internalized via fluid phase. Immunocytochemistry as well a s subcellular fractionation revealed the localization of the mannose r eceptor and MHC class II molecules in distinct subcellular compartment s. The mannose receptor thus functions in rapid internalization and co ncentration of a variety of glycosylated antigens that become availabl e for processing and presentation. This may contribute to the unique c apacity of dendritic cells to generate primary T cell responses agains t infectious agents.