Preferences for uptake of carbohydrate-coated liposomes by C-type lectin receptors as antigen-uptake receptors.

We evaluated the carbohydrate preferences of the C-type lectin receptors (CLRs) SIGNR1, SIGNR3, and Langerin as pathogen-uptake receptors based on uptake of liposomes consisting of cholesterol, DPPC, and various neoglycolipids at molar ratios of 10:10:1 and 10:7:4, respectively, using non-phagocytic CHO cells that express these receptors transiently. SIGNR1-expressing cells ingested liposomes coated with neoglycolipids with terminal mannose residues, such as Man2-, Man3-, and Man5-DPPE, and with a terminal N-acetylglucosamine. SIGNR1 mediated uptake of Man3-DPPE-coated liposomes most efficiently. Uptake of liposomes with lower neoglycolipid content by SIGNR3- or Langerin-expressing cells was slight or negligible, but uptake into these cells was detected for liposomes with higher neoglycolipid content. SIGNR1-expressing cells clearly ingested liposomes coated with Lewis X antigen, whereas SIGNR3- or Langerin-expressing cells barely ingested these liposomes, even at the higher neoglycolipid content. In contrast, SIGNR3 or Langerin, but not SIGNR1, mediated uptake of liposomes coated with blood group H antigen. These results indicate that CLRs with similar carbohydrate-recognition characteristics have distinct properties as pathogen-uptake receptors for carbohydrate-decorated particles.