5). We explain the lack of tumor rejection and DC migration by OX86 treatment in CD40−/− as a consequence of insufficient CD40L upregulation by Tem cells and therefore insufficient DC reactivation in the tumor microenvironment. To demonstrate that OX40 stimulation promoted in vivo the direct adjuvanticity of Tem cells toward DCs via CD40/CD40L,

Tem cells were sorted from tumors 24 h after treatment with OX86 or rat IgG and were co-cultured with WT or CD40−/− BMDCs. After 24 h, BMDC maturation was estimated by the expression of CD80 and CD86 (Fig. 5A). We found that WT BMDCs received a stronger stimulation by Tem cells pre-treated in vivo with OX86, VX-770 in vivo than with isotype matched control Ab. However, CD40-deficient BMDCs could not increase the expression of maturation markers after co-culture with Tem cells obtained from either OX86 or mock-treated tumors (Fig. 5B and C). We cannot exclude that a reverse CD4/CD40L-mediated interplay may occur between Tem cells and DCs, thus explaining the superior capacity of OX40-triggered Tem cells to costimulate WT DCs. Indeed, OX40-stimulated Tem cells, expressing higher CD40L levels, could be more receptive to CD40-mediated signals provided by WT but not CD40-null DCs, thus in turn boosting WT DCs via signals

other than the CD40/CD40L axis, for instance through enhanced cytokine secretion. However, we failed to Resveratrol detect an increased production of IFN-γ, TNF-α, IL-17 or IL-6 ex vivo by tumor-infiltrating lymphocytes (TILs) upon OX86 intratumoral Selleck RG7204 administration (Supporting Information Fig. 6). These data demonstrate that tumor-infiltrating

Tem cells, stimulated in vivo with OX86, directly provided the adequate stimuli for DC ex vivo reactivation in a CD40/CD40L-dependent manner. The effects of OX40 triggering on Treg and Teff cells in tumor rejection were separately investigated. In different contexts, Treg cells may adopt preferential suppression mechanisms among a variety of possibilities 2. IL-10 is one of the best-known cytokines endowed with immune-suppressive functions. Il10 gene expression characterizes Treg-cell signature 30, even though a significant IL-10 expression at the protein level can be detected in naïve mice only in the intestine 15, 31. Treg-cell-derived IL-10 is redundant for the control of systemic autoimmunity but becomes crucial for the control of inflammation at the mucosal interfaces with the external environment, such as in lungs and colon 32. In chronic inflammation-related tumorigenesis, Treg cells may turn from anti- to pro-inflammatory and pro-tumorigenic. Indeed, along the development of colon polyposis, Treg cells lose the ability to secrete the anti-inflammatory IL-10 and switch to the pro-inflammatory and pro-tumorigenic IL-17 33.