title: An increased adjuvanticity of liposomes by the inclusion of phosphatidylserine in immunization with surface-coupled liposomal antigen.
abstract: BACKGROUND
  Exposure of phosphatidylserine (PS) on apoptotic cells is known to result in the enhanced recognition of apoptotic cells by phagocytes. By the inclusion of PS in the lipid component of liposomes, increased liposome immune adjuvant activity was expected.
  
  
  METHODS
  In the present study, two different liposome preparations containing either PS, i.e. PS-liposome, or phosphatidylcholine (PC), i.e. PC-liposome, were made, and macrophage recognition, processing, and antigen presentation of surface-coupled liposomal antigen were compared.
  
  
  RESULTS
  When ovalbumin-liposome conjugates were added to a culture of macrophages, enhanced recognition and processing of ovalbumin by the macrophages were observed by the inclusion of PS in the liposomes. The results correlated well with those regarding macrophage antigen presentation of liposome-coupled ovalbumin. Furthermore, in vivo immunization in mice with ovalbumin-liposome conjugates made with PS-liposomes induced a significantly higher level of anti-ovalbumin IgG antibody production than was induced by ovalbumin-liposome conjugates made with PC-liposomes. IgE-selective unresponsiveness was induced by ovalbumin-liposome conjugates regardless of the lipid components of liposomes.
  
  
  CONCLUSIONS
  These results suggest that the inclusion of PS in liposomes enhances recognition and processing of surface-coupled liposomal antigen by macrophages, and increases liposome immune adjuvant activity.
authors.affiliation: Drug Delivery System Development Division, Nippon Oil and Fat Corporation, Tokyo, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Mori
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Nishida
authors.forename: Naoya
authors.initials: N
authors.lastname: Maekawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamamura
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Michiyuki
authors.initials: M
authors.lastname: Kasai
authors.forename: Maiko
authors.initials: M
authors.lastname: Taneichi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Uchida
mesh_terms: D000276:Adjuvants, Immunologic / Q000737:chemistry* / Q000494:pharmacology*; D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects; D000954:Antigens, Surface / Q000276:immunology; D015195:Drug Design; D007114:Immunization; D007074:Immunoglobulin G / Q000097:blood; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry* / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000737:chemistry / Q000276:immunology*; D010587:Phagocytosis; D010713:Phosphatidylcholines / Q000737:chemistry / Q000494:pharmacology; D010718:Phosphatidylserines / Q000737:chemistry / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000276:immunology; D014611:Vaccination
chemical_list: D000276:Adjuvants, Immunologic; D000954:Antigens, Surface; D007074:Immunoglobulin G; D008055:Lipids; D008081:Liposomes; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D010047:Ovalbumin