These Treg were induced after treatment of primed mice with intact anti-CTLA-4 antibodies. These regulatory T cells inhibit Th1 responses, in vitro and in vivo, and repress experimental intestinal inflammation, by a mechanism involving IL-10 and IDO.

We have investigated the in vivo capacity of resting (and of DC-primed) NK cells to reach the draining lymph nodes.

A vaccination trial with RNA transfected autologous DC was done with overlapping peptides covering the whole protein sequence of the tumor antigens MageA3, MelanA and Survivin.

The capacity of splenic DC, pulsed in vitro with protein antigens or peptides, to induce immunity was monitored after transfer into syngeneic animals. To improve existing strategies, the amplitude and polarisation of T cell responses was monitored in the presence or absence of regulatory T cells.

In order to test homogeneous yeast populations, pure spore cultures were obtained by using this strain whose sporulation efficiency is 100%. To prepare spores, cells were grown on YPD plates, replicated on SPOIV medium (2% potassium acetate, 0.25% yeast extract, 0,1% glucose). Zymolyase (2 mg/ml) was used to digest ascum and liberate spores. Zymoliase was inactivated by heat (65°C for 2 minutes) and washed away carefully together with the remainings of the empty ascus, by resuspending twice the spore culture in 500 µl of distilled water centrifuging and disc...

Cells stained in PE-alpha DC80 in PBS + 2 % FCS for FACS analysis for activation markers.

The D2SC1/Flt3-DC were stained (Mini67-1KT or Mini26-1KT (PKH67/PKH26 green/red fluorescent cell linker mini kit for general cell membrane labelling) from Sigma) for a process of dead cell uptake.

The dead cells were stained (Mini67-1KT or Mini26-1KT (PKH67/PKH26 green/red fluorescent cell linker mini kit for general cell membrane labelling) from Sigma) for a process of dead cell uptake by DC.

These cells were stained with anti-CD11c antibodies for a process of dead cell uptake by DC.

iNKT cells were stimulated in vivo with the synthetic CD1d ligand alpha-GalCer. This significantly enhanced immune responses to protein and peptide based vaccines, due to rapid iNKT dependent DC maturation.

These plasmacytoid pDC that were stimulated with both CpG and the TLR-7 ligand R848 were shown to produce very high levels of IL-12p70 (in the ng/ml range per 5 x 105 cells/ml) and IFN-gamma.

These T cells stem from an elutriation process from a metastatic lesion of stage III/IV melanoma patients. Subsequently, these T cells will be expanded by co-culture with tumor lysate loaded DC.

We have used “conventional” techniques to monitor the vaccine induced specific anti-tumor T cell responses (thymidine-incorporation, ELISA, LDA and ELISPOT assays). We have set the staining conditions for the HLA-DR*1101 tetramers loaded with tetanus toxoid and MAGE-3 peptides corresponding promiscuous CD4+ T cell epitopes. Antigen-specific CD4+ T cells are visualized after in vitro short-term expansion; we are currently optimizing the conditions for the ex-vivo staining.

We attempted to improve the adoptive transfer protocol for immunotherapy by stimulating T cells with monocyte derived DC pulsed with tumor lysate, instead of simply adding tumor lysate into PBMC cultures. T cells raised exhibited some tumor reactivity and outgrowth of a distinct T cell population could be observed.

It was found that these cells do not migrate to lymph nodes in the steady state.

By using TAP deficient cells, we found that TAP is also necessary for the process of presentation of the antigen in MHC class I. We further characterized the antigen depot by confocal microscopy and found that the antigen co-localized with the lysosomal marker LAMP1, but not with the endosomal marker EEA1, TAP, MHC class I or MHC class II. We conclude that the antigen depot is a storage compartment and not a loading compartment. We have started to examine depot formation by targeting antigen to other receptors. For example, we have found that presentation ...

Concerning « in vivo » responses to Ags, we studied the kinetics of effector genes expression and association in TCR-Tg CD8 cells responding to the male antigen and to Listeria-OVA.

For studying in vivo responses to antigens, we initiated a long program comparing the behaviour of TCR-Tg cells specific for GP-33 peptide.

We have determined mechanisms for DC-induced Th1 development and the molecular pathways for inducing Th1 cells producing IFN-gamma solely, or Th1 cells producing IFN-gamma and IL-10, which have important implications for regulation of the immune response to eradicate pathogens with minimum pathology.

We have determined mechanisms for DC-induced Th1 development and the molecular pathways for inducing Th1 cells producing IFN-gamma solely, or Th1 cells producing IFN-gamma and IL-10, which have important implications for regulation of the immune response to eradicate pathogens with minimum pathology.