title: Extending the CD4(+) T-cell epitope specificity of the Th1 immune response to an antigen using a Salmonella enterica serovar typhimurium delivery vehicle.
abstract: We analyzed the CD4 T-cell immunodominance of the response to a model antigen (Ag), MalE, when delivered by an attenuated strain of Salmonella enterica serovar Typhimurium (SL3261*pMalE). Compared to purified MalE Ag administered with adjuvant, the mapping of the peptide-specific proliferative responses showed qualitative differences when we used the Salmonella vehicle. We observed the disappearance of one out of eight MalE peptides' T-cell reactivity upon SL3261*pMalE immunization, but this phenomenon was probably due to a low level of T-cell priming, since it could be overcome by further immunization. The most striking effect of SL3261*pMalE administration was the activation and stimulation of new MalE peptide-specific T-cell responses that were silent after administration of purified Ag with adjuvant. Ag presentation assays performed with MalE-specific T-cell hybridomas showed that infection of Ag-presenting cells by this intracellular attenuated bacterium did not affect the processing and presentation of the different MalE peptides by major histocompatibility complex (MHC) class II molecules and therefore did not account for immunodominance modulation. Thus, immunodominance of the T-cell response to microorganisms is governed not only by the frequency of the available T-cell repertoire or the processing steps in Ag-presenting cells that lead to MHC presentation but also by other parameters probably related to the infectious process and to the bacterial products. Our results indicate that, upon infection by a microorganism, the specificity of the T-cell response induced against its Ags can be much more effective than with purified Ags and that it cannot completely be mimicked by purified Ags administered with adjuvant.
authors.affiliation: Unité de Biologie des Régulations Immunitaires, Institut Pasteur, Paris, France. rloman@pasteur.fr
authors.forename: R
authors.initials: R
authors.lastname: Lo-Man
authors.forename: J P
authors.initials: JP
authors.lastname: Langeveld
authors.forename: E
authors.initials: E
authors.lastname: Dériaud
authors.forename: M
authors.initials: M
authors.lastname: Jehanno
authors.forename: M
authors.initials: M
authors.lastname: Rojas
authors.forename: J M
authors.initials: JM
authors.lastname: Clément
authors.forename: R H
authors.initials: RH
authors.lastname: Meloen
authors.forename: M
authors.initials: M
authors.lastname: Hofnung
authors.forename: C
authors.initials: C
authors.lastname: Leclerc
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D018528:ATP-Binding Cassette Transporters; D019883:Alkyl and Aryl Transferases; D000818:Animals; D017951:Antigen Presentation; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000382:microbiology; D000942:Antigens, Bacterial; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology*; D004333:Drug Administration Routes; D018604:Epitope Mapping; D000939:Epitopes; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007115:Immunization Schedule; D016056:Immunodominant Epitopes; D008213:Lymphocyte Activation; D058619:Maltose-Binding Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D009004:Monosaccharide Transport Proteins; D009842:Oligopeptides / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology; D033902:Periplasmic Binding Proteins; D011994:Recombinant Proteins / Q000276:immunology; D012486:Salmonella typhimurium / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology*
chemical_list: D018528:ATP-Binding Cassette Transporters; D000942:Antigens, Bacterial; D002352:Carrier Proteins; D000939:Epitopes; D029968:Escherichia coli Proteins; D000949:Histocompatibility Antigens Class II; D016056:Immunodominant Epitopes; C461619:MalE protein, E coli; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D009842:Oligopeptides; D010446:Peptide Fragments; D033902:Periplasmic Binding Proteins; D011994:Recombinant Proteins; C461599:maltose transport system, E coli; D019883:Alkyl and Aryl Transferases; D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase