CD303 is an approximately 38 kDa type II transmembrane glycoprotein with an extracellular C-type lectin domain. It is a specific marker of plasmacytoid dendritic cells, and plays roles in capturing of pathogen-related oligosaccharide-containing antigens by them, and in their presentation to T cells. CD303 also mediates a potent inhibition of interferon alpha/beta production in plasmacytoid dendritic cells, thus it represents a potential target for lupus erythematosus therapy.