Effects of lipid A on the immunologic properties of liposomal model membranes.
Incorporation of lipid A influences the immunogenic properties of liposomal model membranes that carry N-(hapten)-substituted derivatives of phosphatidylethanolamine as antigenic determinants. These effects of lipid A include a marked enhancement of the hapten-specific response; abolition of the requirement of critical threshold epitope density for liposomal immunogenicity; and conversion of liposomes from a thymus-independent type 2 to a thymus-independent type 1 immunogen. Recent experiments demonstrate that an optimal in vitro response to liposomes--although originally classified as thymus-independent on the basis of conventional criteria--requires two T cell factors, interleukin-2 and interleukin-X, which are also involved in the response to a classic thymus-dependent immunogen. Incorporation of lipid A has no qualitative effect on the dependence of liposomal immunogenicity on these lymphokines.
D000818:Animals; D002003:Brucella abortus / Q000276:immunology; D000939:Epitopes / Q000032:analysis; D005260:Female; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000494:pharmacology; D008050:Lipid A / Q000494:pharmacology*; D008081:Liposomes / Q000276:immunology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008954:Models, Biological; D010714:Phosphatidylethanolamines / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
D000939:Epitopes; D007376:Interleukin-2; D008050:Lipid A; D008081:Liposomes; D010714:Phosphatidylethanolamines