NR AWMQ
AU Rosset,M.B.; Sacquin,A.; Adam,M.; Eloit,M.
TI MHC class I restricted peptides from prion protein can induce specific cytotoxic T cells in tolerant mice
QU International Conference - Prion 2006: Strategies, advances and trends towards protection of society - 3.10.-6.10.2006, Torino, Italy, Lingotto Conference Centre - Poster sessions THE-15
PT Konferenz-Poster
AB It is fundamental to improve the methods of prevention and therapy of Transmissible Spongiform Encephalopathies (TSE) for which no efficient therapy is available today. The disease is associated with conformational changes of a normal host protein, PrPc, which is converted into a protease resistant form, PrPsc. Whereas antibodies against native PrPc were shown experimentally to efficiently control PrPsc accumulation and pathogenesis, the possibility that cytotoxic T lymphocytes (CTL) directed against PrP-derived peptides would clear PrPsc-producing cells has never been explored. The objective of this work was to generate CD8+ CTL against PrP by engineering potent immunogens to overcome tolerance in C57BL/6 mice. Immunization strategies will include the use of 1) PrP low affinity peptides that have been modified to increase their binding to MHC class I molecules, 2) the elimination of CD4+CD25+ regulatory T (Tr) cells to raise or improve the generation of T cells specific for PrP and 3) recombinant adenoviruses (Ads) vectors expressing homologous PrP genes or minigenes encoding MHC class I-binding peptides. In a first step, we immunized C57BL/6 mice with modified PrP nonamer peptides designed to bind with high affinity to H-2Db molecules and measured the frequency of IFN secreting specific T cells in response to the modified but also to the natural peptides. The cytotoxic potential of splenocytes from immunized mice was evaluated by their capacity to lyse modified and natural peptide-loaded targets in in vitro and in vivo assays. Among ten H-2Db-restricted PrP peptides, only few were able to induce CTL efficient in vitro and in vivo. The removal of CD4+CD25+ Tr cells by pretreatement of recipient with cyclophosphamide before immunization significantly increased the frequency of IFN secreting T cells specific for the natural and modified peptides. Experiments using immunization with recombinant Ads or plasmids expressing the entire PrP molecule or minigenes encoding the relevant peptides are in progress. Further work will be performed to verify that some of the peptides that induce efficient CTL, are naturally processed and presented on the cell surface of PrP-expressing mice, and to test the protective capacity of these effectors on PrPsc accumulation and prion disease progression.
AD M. Rosset, A. Sacquin: INSERM U712, Hôpital St Antoine, Paris, France; M. Adam, M. Eloit: UMR1161 INRA-AFSSA-ENVA, Maisons Alfort, France
SP englisch
PO Italien