CpG-DNA aided cross-presentation of soluble antigens by dendritic cells.
For cross-presentation immature dendritic cells (DC) require enhanced antigen (Ag) uptake and a maturation signal to prime for MHC class I-restricted CTL responses in vivo. While immunostimulatory CpG-DNA provides, via TLR9, the maturation signal, CpG-DNA linked to Ag augments cellular Ag uptake. In this study we show that CpG-DNA ovalbumin (OVA) conjugates trigger in vivo peptide-specific CTL responses at tenfold lower Ag doses compared to a mixture of CpG-DNA plus OVA. We provide evidence that CpG-DNA-OVA conjugates shift OVA uptake by immature DC from the presumably inefficient fluid phase pinocytosis to efficient DNA receptor-mediated endocytosis. Since the DNA-binding receptor mediating endocytosis lacks any sequence specificity, cellular uptake of OVA conjugated with either stimulatory or non-stimulatory oligonucleotides (ODN) is equally enhanced. As a consequence cross-linking of OVA with either stimulatory or non-stimulatory DNA yields, via enhanced OVA uptake, efficient generation and presentation of the dominant OVA-CTL epitope SIINFEKL. However, only stimulatory CpG-ODN cross-linked to OVA provide the DC maturation signal required to trigger robust primary CTL responses towards the cross-presented MHC class I complexed T cell epitope SIINFEKL. Our studies show that stimulatory CpG-ODN linked to Ag fulfill a dual role: enhancement of Ag uptake yielding efficient Ag cross-presentation by DC and in addition, their activation into professional DC.
Maurer
Tobias
T
Institute of Medical Microbiology, Immunology and Hygiene, Technical University of Munich, Munich, Germany.
Heit
Antje
A
Hochrein
Hubertus
H
Ampenberger
Franziska
F
O'Keeffe
Meredith
M
Bauer
Stefan
S
Lipford
Grayson B
GB
Vabulas
Ramunas M
RM
Wagner
Hermann
H
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects*; D002460:Cell Line; D003713:Dendritic Cells / Q000276:immunology*; D004527:Egg Proteins / Q000276:immunology; D018984:Epitopes, T-Lymphocyte; D051379:Mice; D008810:Mice, Inbred C57BL; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D010047:Ovalbumin / Q000276:immunology; D010446:Peptide Fragments; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D000276:Adjuvants, Immunologic; C408982:CPG-oligonucleotide; D004527:Egg Proteins; D018984:Epitopes, T-Lymphocyte; C110366:OVA-8; D009838:Oligodeoxyribonucleotides; D010446:Peptide Fragments; D010047:Ovalbumin