title: Differential biodistribution of encapsulated and surface-linked liposomal antigens.
abstract: The biodistribution of liposomal antigens either encapsulated in or surface-linked to liposomes of similar composition was studied over time following intravenous injection and the results analyzed in relation to adjuvanticity. The two formulations were shown to behave very differently in vivo. While encapsulated antigen was rapidly focused to liver and spleen as expected, surface-linked antigen exhibited a more disseminated distribution which parallels that of the free protein. In dual-labelling experiments, it was also shown that encapsulated antigen remains associated with its liposomal vehicle in contrast to surface-linked antigen which is rapidly dissociated. This dissociation was apparently neither due to an exchange with plasma lipoproteins nor to a direct action of blood constituents. Besides, it was found that surface-linked antigen was rapidly accumulated in the carcass. We propose that the retention of the surface-linked antigen in the carcass results from a pre-processing of the protein involving more probably mononuclear phagocytes. This pre-processing might in turn favor the dissociation of the protein from the liposomes in a form that allows its dissemination in the whole organism and its interaction with more efficient antigen presenting cells such as for example Langerhans or dendritic cells.
authors.affiliation: Groupe de Recherche en Biotechnologie des Membranes, Département de Chimie-Biologie, Université du Québec à Trois-Rivières, Québec, Canada.
authors.forename: H M
authors.initials: HM
authors.lastname: Thérien
authors.forename: E
authors.initials: E
authors.lastname: Shahum
mesh_terms: D000818:Animals; D000941:Antigens / Q000008:administration & dosage / Q000378:metabolism*; D002214:Capsules; D003207:Conalbumin / Q000008:administration & dosage / Q000276:immunology / Q000493:pharmacokinetics*; D004337:Drug Carriers; D005260:Female; D007275:Injections, Intravenous; D007457:Iodine Radioisotopes; D008081:Liposomes; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011865:Radioisotope Dilution Technique; D013329:Structure-Activity Relationship; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D000941:Antigens; D002214:Capsules; D004337:Drug Carriers; D007457:Iodine Radioisotopes; D008081:Liposomes; D003207:Conalbumin