NR AXIL
AU Bachy,V.; Ballerini,C.; Gourdain,P.; Rosset,M.; Carnaud,C.
TI Vaccination with Peptide-Loaded Dendritic Cells Overcomes Self Tolerance and Confers Resistance to Scrapie
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Pathology and Pathogenesis P03.59
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB
Prion diseases are fatal neurodegenerative disorders caused by the accumulation of an abnormal protein, PrPsc, an isoform of a host-encoded protein (PrPc). Since PrPsc is seen as self by the patient immune system, strong tolerance must be overcome in order to design efficient immunoprophylactic and immunotherapeutic treatments. The aim of the present study was to find out whether immunisation with dendritic cells (DC) might raise T and B cell responses against PrP in wild type mice.
Bone-marrow derived dendritic cells (DCs) were generated in vitro from PrP-deficient or sufficient mice in the presence of GM-CSF for 7 days. On d7, LPS was added for DC maturation. On d8, DC were collected and loaded for 4 h with immunogenic prion peptides p97-128 (p5) or p158-187 (p9). Peptide-loaded and control unloaded DC were injected i.p.. One or 2 DC injections were performed at two week interval. The CD4+ T cell response was assessed by IFN-g and IL-4 ELISPOT while the B cell response was evaluated by indirect immunofluorescence on transfected EL-4 cells
expressing high levels of cell surface PrPc.
DC loaded with p5 triggered p5-specific IL-4 spots in 50% of mice, but no IFN-g. Peptide 9 achieved stronger stimulation manifested by IFN-g and IL-4 spots in most mice. Antibodies against native PrPc were detected in sera of 70% of mice, irrespective of the immunising peptide.
Protection following DC vaccination was also evaluated. Ten PrP-sufficient mice were vaccinated with p5-loaded DC versus 12 controls injected with PBS. Seven days after the second DC vaccination, mice were infected i.p. with 139A. DC boosts were performed monthly while control mice received only PBS. The median incubation period was 191 days for the vaccinated group versus 167 days for controls (P < 0.0001). Median survival period was 254 days for the vaccinated group versus 214 days for controls (P < 0.0001). Vaccinated mice had also a longer clinical phase (p=0.007). Interestingly, there was a definite correlation between antibody production at 45 days post-infection and survival time, which suggests that anti-PrP antibodies slow down lymphoinvasion. Two vaccinated mice which had the highest antibody titers are still alive 400 days post-infection and do not display any sign of autoimmunity.
AD V. Bachy, P. Gourdain, M. Rosset, C. Carnaud, Hospital Saint-Antoine, UMR U712, France; C. Ballerini, University of Firenze, Italy
SP englisch
PO Schottland