The effect of surface sugars on liposomes in immunopotentiation

Abstract

The effect of surface sugars of liposomes on the immunological responses to entrapped antigen has been investigated. α-Mannose and β-galactose were grafted on the surface of liposomes containing lysozyme by covalent coupling of p-aminophenyl-D-glycosides to phosphatidyl ethanolamine liposomes using glutaraldehyde. Subcutaneous administration of antigen entrapped in β-galactose liposomes stimulated an antibody response comparable to that elicited by sugar-free neutral liposomes. However, α-mannose bearing liposomes with entrapped lysozyme elicited an immune response similar to that induced by lysozyme in saline. Based on these observations it is suggested that α-mannose liposomes, that are specifically recognized by macrophages, are taken up rapidly by receptor mediated endocytosis and that the entrapped antigen is then rapidly degraded, resulting in low antibody production.