title: von Willebrand factor binds to the surface of dendritic cells and modulates peptide presentation of factor VIII.
abstract: It has been proposed that von Willebrand factor might affect factor VIII immunogenicity by reducing factor VIII uptake by antigen presenting cells. Here we investigate the interaction of recombinant von Willebrand factor with immature monocyte-derived dendritic cells using flow cytometry and confocal microscopy. Surprisingly, von Willebrand factor was not internalized by immature dendritic cells, but remained bound to the cell surface. As von Willebrand factor reduces the uptake of factor VIII, we investigated the repertoire of factor VIII presented peptides when in complex with von Willebrand factor. Interestingly, factor VIII-derived peptides were still abundantly presented on major histocompatibility complex class II molecules, even though a reduction of factor VIII uptake by immature dendritic cells was observed. Inspection of peptide profiles from 5 different donors showed that different core factor VIII peptide sequences were presented upon incubation with factor VIII/von Willebrand factor complex when compared to factor VIII alone. No von Willebrand factor peptides were detected when immature dendritic cells were pulsed with different concentrations of von Willebrand factor, confirming lack of von Willebrand factor endocytosis. Several von Willebrand factor derived peptides were recovered when cells were pulsed with von Willebrand factor/factor VIII complex, suggesting that factor VIII promotes endocytosis of small amounts of von Willebrand factor by immature dendritic cells. Taken together, our results establish that von Willebrand factor is poorly internalized by immature dendritic cells. We also show that von Willebrand factor modulates the internalization and presentation of factor VIII-derived peptides on major histocompatibility complex class II.
authors.affiliation: Department of Plasma Proteins, Sanquin-AMC Landsteiner Laboratory, Amsterdam, the Netherlands Current address: Harvard Medical School Program in Cellular and Molecular Medicine, Boston Children's Hospital, USA.
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Sorvillo
authors.affiliation: Department of Plasma Proteins, Sanquin-AMC Landsteiner Laboratory, Amsterdam, the Netherlands.
authors.forename: Robin B
authors.initials: RB
authors.lastname: Hartholt
authors.affiliation: Department of Plasma Proteins, Sanquin-AMC Landsteiner Laboratory, Amsterdam, the Netherlands.
authors.forename: Esther
authors.initials: E
authors.lastname: Bloem
authors.affiliation: Department of Plasma Proteins, Sanquin-AMC Landsteiner Laboratory, Amsterdam, the Netherlands.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Sedek
authors.affiliation: Department of Immune Pathology, Sanquin-AMC Landsteiner Laboratory, Amsterdam, the Netherlands.
authors.forename: Anja
authors.initials: A
authors.lastname: ten Brinke
authors.affiliation: Department of Plasma Proteins, Sanquin-AMC Landsteiner Laboratory, Amsterdam, the Netherlands.
authors.forename: Carmen
authors.initials: C
authors.lastname: van der Zwaan
authors.affiliation: Department of Plasma Proteins, Sanquin-AMC Landsteiner Laboratory, Amsterdam, the Netherlands.
authors.forename: Floris P
authors.initials: FP
authors.lastname: van Alphen
authors.affiliation: Department of Plasma Proteins, Sanquin Blood Supply Foundation, Amsterdam and the Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, the Netherlands.
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Meijer
authors.affiliation: Department of Plasma Proteins, Sanquin-AMC Landsteiner Laboratory, Amsterdam, the Netherlands j.voorberg@sanquin.nl.
authors.forename: Jan
authors.initials: J
authors.lastname: Voorberg
mesh_terms: D000595:Amino Acid Sequence; D017951:Antigen Presentation; D001665:Binding Sites; D002454:Cell Differentiation; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D004705:Endocytosis; D005169:Factor VIII / Q000276:immunology* / Q000378:metabolism; D059811:HLA-DRB1 Chains / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D009000:Monocytes / Q000166:cytology / Q000276:immunology; D010455:Peptides / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D061251:Primary Cell Culture; D011485:Protein Binding; D011994:Recombinant Proteins / Q000276:immunology / Q000378:metabolism; D014841:von Willebrand Factor / Q000276:immunology* / Q000378:metabolism
chemical_list: D059811:HLA-DRB1 Chains; D010455:Peptides; D011994:Recombinant Proteins; D014841:von Willebrand Factor; D005169:Factor VIII