These K/O mice were studied with regard to responses to viral infections. We used the mouse pox virus Ectromelia and MVA-BN.

In order to identify the APCs that were responsible for the development of this state of immune tolerance, we aimed to generate a transgenic mouse that express a recombinant fluorescent protein in the mammary glands, an approach that should result in high levels of expression of the fluorescent protein in the milk. We thus should be able to detect the cells that capture, degrade and present this antigen to T cells. Since we had previously generated a monoclonal antibody, 2C44, that reacts to a peptide derived from the Leishmania LACK protein bound to I-Ad MHC ...

The immunotherapy potential of DC, pulsed with tumor antigens, was evaluated in EG7-OVA and P815 tumor models. Depletion of natural regulatory T cells in these tumor bearing mice resulted in rejection of P815 cells, but not EG7-OVA, suggesting that regulatory T cells have a stronger impact on immune responses against weakly immunogenic or auto-antigen (P1A).

These mice were used to study « 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.

These mice were treated with intact anti-CTLA-4 antibodies. This induced the development of regulatory T cells expressing high levels of ICOS and producing IL-10. 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.

Tumor growth is supported by tumor stroma, such as tumor associated macrophages (TAM) and tumor associated dendritic cells (TADC). We have recently reported that TAM display massive nuclear localization of the p50 NF-kB inhibitory homodimer, which correlates with impaired inflammatory functions.The functional significance of this observation was demonstrated in p50 NF-kB deficient mice, which displayed tumor growth inhibition.

The effect of environmental factors on development of high affinity CTL was investigated using a system whereby OT-1 cells were primed in vitro by engineered APC. After a 20 h priming phase, CTL were transferred to recipient mice that were either naïve, or had been injected with activated dendritic cells one day earlier, thus creating a reactive lymph node.

The animal(s) were immunized in vivo with in vitro matured DC and / or treated using a maturation signal.

The effect of environmental factors on development of high affinity CTL was investigated using a system whereby OT-1 cells were primed in vitro by engineered APC. After a 20 h priming phase, CTL were transferred to recipient mice that were either naïve, or had been injected with activated dendritic cells one day earlier, thus creating a reactive lymph node.

Using pharmacological inhibitors, or macrophages and DC from mice carrying a null mutation in MAP kinase signalling molecule(s), we have evidence for a role of certain MAP kinases in the regulation of IL-10 and IL-12, IFN-gamma production.

Subcutaneous injection of hypoxic DCs into the footpads of mice results in defective DC homing to draining lymph nodes, but enhanced leukocyte recruitment at the site of injection.

We infected mice with CD8+ T-cells primed with or without the influence of a reactive lymph node with a flu-virus encoding the specific antigen. After several days we determined the viral load in the lungs with RT-PCR. The results show that in mice with CD8+ T-cells primed with a reactive lymph node the viral load in the lungs was significantly smaller then in a control mice.

We showed that, in the absence of adjuvants, DEX mediate potent antigen dependent-antitumor effects against preestablished tumors in mice pretreated with immunopotentiating dosing of cyclophosphamide (CTX).

We have immunized mice with human DC derived-exosomes and generated hybridomas that produce antibodies recognizing at least the human exosomes.

By immunizing mice with ovalbumin-conjugated anti-Siglec-H Ab in the presence of CpG, we demonstrated generation of antigen-specific CD8 T cells in vivo.

IDO appears critical for the regulation of TNBS colitis upon CTLA-4 engagement, as the beneficial effect of anti-CTLA-4 treatment was lost in IDO-deficient mice. By contrast, the absence of IDO did not alter the course of inflammation in mice injected with TNBS only, an unexpected finding which suggests that IDO-dependent counter-regulation requires other factors/cells in addition to IDO production and T cell activation by TNBS.

These K/O mice were studied with regard to responses to viral infections. We used the mouse pox virus Ectromelia and MVA-BN. Coinfection with MVA-BN and Ectromilia protected the IFNalpha receptor -/- mice. The data show that MVA-BN can induce potent innate immune responses able to control viral replication to allow the specific immune response to eliminate Ectromelia in immune deficient mice.

Hu-SCID mice were used to study responses to EBV and HIV.

These mice were infected with both CXCR4 as well as CCR5 tropic HIV-1 strains. HIV causes a disseminated infection and spreads in all newly generated lymphoid tissues, thus closely resembling HIV infection in humans. We are now aiming to improve the recipient mouse background by co-transplanting human mesenchymal stroma cells, and by adding human cytokines as well as human MHC. Furthermore, we use the mice to evaluate targeted therapies directed at human immune system cells as T cells, B cells, and dendritic cells.

We established “human hemato-lymphoid-system mice” by transplanting human CD34+ cord blood cells into irradiated newborn Rag2-/-gc-/- mice, leading to de novo development of human B, T, and dendritic cells.