title: Dendritic cell-lysosomal-associated membrane protein (LAMP) and LAMP-1-HIV-1 gag chimeras have distinct cellular trafficking pathways and prime T and B cell responses to a diverse repertoire of epitopes.
abstract: Ag processing is a critical step in defining the repertoire of epitope-specific immune responses. In the present study, HIV-1 p55Gag Ag was synthesized as a DNA plasmid with either lysosomal-associated membrane protein-1 (LAMP/gag) or human dendritic cell-LAMP (DC-LAMP/gag) and used to immunize mice. Analysis of the cellular trafficking of these two chimeras demonstrated that both molecules colocalized with MHC class II molecules but differed in their overall trafficking to endosomal/lysosomal compartments. Following DNA immunization, both chimeras elicited potent Gag-specific T and B cell immune responses in mice but differ markedly in their IL-4 and IgG1/IgG2a responses. The DC-LAMP chimera induced a stronger Th type 1 response. ELISPOT analysis of T cell responses to 122 individual peptides encompassing the entire p55gag sequence (15-aa peptides overlapping by 11 residues) showed that DNA immunization with native gag, LAMP/gag, or DC-LAMP/gag induced responses to identical immunodominant CD4+ and CD8+ peptides. However, LAMP/gag and DC-LAMP/gag plasmids also elicited significant responses to 23 additional cryptic epitopes that were not recognized after immunization with native gag DNA. The three plasmids induced T cell responses to a total of 39 distinct peptide sequences, 13 of which were induced by all three DNA constructs. Individually, DC-LAMP/gag elicited the most diverse response, with a specific T cell response against 35 peptides. In addition, immunization with LAMP/gag and DC-LAMP/gag chimeras also promoted Ab secretion to an increased number of epitopes. These data indicate that LAMP-1 and DC-LAMP Ag chimeras follow different trafficking pathways, induce distinct modulatory immune responses, and are able to present cryptic epitopes.
authors.affiliation: Department of Pharmacology and Molecular Sciences, The Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
authors.forename: Luciana B
authors.initials: LB
authors.lastname: Arruda
authors.forename: Del
authors.initials: D
authors.lastname: Sim
authors.forename: Priya R
authors.initials: PR
authors.lastname: Chikhlikar
authors.forename: Milton
authors.initials: M
authors.lastname: Maciel
authors.forename: Kenji
authors.initials: K
authors.lastname: Akasaki
authors.forename: J Thomas
authors.initials: JT
authors.lastname: August
authors.forename: Ernesto T A
authors.initials: ET
authors.lastname: Marques
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D002465:Cell Movement / Q000235:genetics / Q000276:immunology*; D003713:Dendritic Cells / Q000378:metabolism*; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D005260:Female; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D051907:Lysosomal Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D050506:Mutant Chimeric Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
chemical_list: D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte; D015683:Gene Products, gag; D051907:Lysosomal Membrane Proteins; D050506:Mutant Chimeric Proteins