title: Endocytosis of an HIV-derived lipopeptide into human dendritic cells followed by class I-restricted CD8(+) T lymphocyte activation.
abstract: CD8(+) T lymphocytes, which are major immune effectors, require primary stimulation by dendritic cells (DC) presenting MHC class I molecule-bound epitopes. Sensitization to exogenous protein epitopes that are not synthesized in DC, such as cross-priming, is obtained through pathways leading to their association with MHC class I. To follow class I-restricted pathways in human DC, we have tracked a lipopeptide derived from the conserved HLA-A*0201-restricted HIV-1 reverse transcriptase 476-484 epitope, by N-terminal addition of an Nepsilon-palmytoyl-lysine. Indeed, lipopeptides elicit cytotoxic responses from CD8(+) T lymphocytes, whereas peptides without a lipid moiety do not. The lipopeptide and its parent peptide were labeled unequivocally by rhodamine to study their entry into immature monocyte-derived human DC by confocal microscopy. The lipid moiety induced endocytosis of the lipopeptide, assessed by rapid entry into vesicles, colocalization with Dextran-FITC and dependence on energy. Internalization occurred even when actin filaments were depolymerized by Cytochalasin B. This internalization induced functional stimulation of specific CD8(+) T lymphocytes in IFN-gamma ELISPOT assays. The peptide alone was not visualized inside the DC and was presented through direct surface association to HLA-A*0201. Therefore, lipopeptides are a unique opportunity to define precisely the pathways that lead exogenous proteins to associate with MHC class I molecules in DC. The results will also be useful to design lipopeptide vaccines.
authors.affiliation: INSERM U445, ICGM, Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Andrieu
authors.forename: E
authors.initials: E
authors.lastname: Loing
authors.forename: J F
authors.initials: JF
authors.lastname: Desoutter
authors.forename: F
authors.initials: F
authors.lastname: Connan
authors.forename: J
authors.initials: J
authors.lastname: Choppin
authors.forename: H
authors.initials: H
authors.lastname: Gras-Masse
authors.forename: D
authors.initials: D
authors.lastname: Hanau
authors.forename: A
authors.initials: A
authors.lastname: Dautry-Varsat
authors.forename: J G
authors.initials: JG
authors.lastname: Guillet
authors.forename: A
authors.initials: A
authors.lastname: Hosmalin
mesh_terms: D017951:Antigen Presentation; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002450:Cell Communication / Q000276:immunology*; D002460:Cell Line; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology*; D004705:Endocytosis / Q000276:immunology; D015488:HIV Antigens / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation
chemical_list: D015488:HIV Antigens; D015395:Histocompatibility Antigens Class I