Immunogenicity of liposomal model membranes sensitized with spin-labeled haptens and topographical distribution of haptens on the membranes.
The relation between the in vitro immunogenicity of phosphatidylcholine liposomes containing 2,4-dinitrophenyl-6-N-aminocaproylphosphatidylethanolamine (DNP-Cap-PE) as a hapten and the topographical distribution of the haptens on lipid membranes was studied. In distearoylphosphatidylcholine liposomes, the immunogenicity increased with increase of cholesterol content in the liposomal membranes. The electron spin resonance spectra of spin-labeled DNP-Cap-PE in distearoylphosphatidylcholine liposomes indicated that cholesterol affected the topographical distribution of spin-labeled DNP-Cap-PE on the membranes. In the absence of cholesterol, a considerable amount of haptens was clustered on the distearoylphosphatidylcholine membranes, but with increase of cholesterol, random distribution of the haptens on the membranes increased. The cholesterol-dependent change in the topographical distribution of the haptens on the membranes paralleled the change of immunogenicity, i.e., the immunogenicity was low when haptens were clustered on the liposomal membranes. Haptens arranged at a proper distance on the membranes may be required for optimum immune response.
D000818:Animals; D002478:Cells, Cultured; D002784:Cholesterol / Q000494:pharmacology; D005227:Fatty Acids / Q000032:analysis; D006241:Haptens / Q000276:immunology*; D006462:Hemolytic Plaque Technique; D008081:Liposomes / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013113:Spin Labels; D013154:Spleen / Q000166:cytology
D005227:Fatty Acids; D006241:Haptens; D008081:Liposomes; D013113:Spin Labels; D002784:Cholesterol