title: Composition of MHC class II-enriched lipid microdomains is modified during maturation of primary dendritic cells.
abstract: Dendritic cells (DCs) are the most potent antigen presenting cells. Major histocompatibility complex (MHC) class II molecule expression changes with maturation; immature DCs concentrate MHC class II molecules intracellularly, whereas maturation increases surface expression of MHC class II and costimulatory molecules to optimize antigen presentation. Signal transduction via MHC class II molecules localized in lipid microdomains has been described in B lymphocytes and in the THP-1 monocyte cell line. We have characterized MHC class II molecules throughout human DC maturation with particular attention to their localization in lipid-rich microdomains. Only immature DCs expressed empty MHC class II molecules, and maturation increased the level of peptide-bound heterodimers. Ligand binding to surface human leukocyte antigen (HLA)-DR induced rapid internalization in immature DCs. The proportion of cell-surface detergent-insoluble glycosphingolipid-enriched microdomain-clustered HLA-DR was higher in immature DCs despite the higher surface expression of HLA-DR in mature DCs. Constituents of HLA-DR containing microdomains included the src kinase Lyn and the cytoskeletal protein tubulin in immature DCs. Maturation modified the composition of the HLA-DR-containing microdomains to include protein kinase C (PKC)-delta, Lyn, and the cytoskeletal protein actin, accompanied by the loss of tubulin. Signaling via HLA-DR redistributed HLA-DR and -DM and PKC-delta as well as enriching the actin content of mature DC microdomains. The increased expression of HLA-DR as a result of DC maturation was therefore accompanied by modification of the spatial organization of HLA-DR. Such regulation could contribute to the distinct responses induced by ligand binding to MHC class II molecules in immature versus mature DCs.
authors.affiliation: INSERM U396 and. IDM (Immuno-Designed Molecules), Institut Biomédical des Cordeliers, Paris, France.
authors.forename: Niclas
authors.initials: N
authors.lastname: Setterblad
authors.forename: Corinne
authors.initials: C
authors.lastname: Roucard
authors.forename: Claire
authors.initials: C
authors.lastname: Bocaccio
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Abastado
authors.forename: Dominique
authors.initials: D
authors.lastname: Charron
authors.forename: Nuala
authors.initials: N
authors.lastname: Mooney
mesh_terms: D000199:Actins / Q000032:analysis; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology / Q000648:ultrastructure; D006684:HLA-DR Antigens / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D021962:Membrane Microdomains / Q000737:chemistry* / Q000276:immunology; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D051745:Protein Kinase C-delta; D014404:Tubulin / Q000032:analysis; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D000199:Actins; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II; D010446:Peptide Fragments; D014404:Tubulin; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; C497258:PRKCD protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta