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International audience; We previously demonstrated an accumulation of tumor-reactive CD4 + CD8 + double positive (DP) T cells within melanoma-infiltrating lymphocytes, supporting their role in the regulation of anti-tumor immune responses. Similarly to their CD8 + counterparts, intra-tumor DP T cells are MHC class-I restricted but differed by a limited lytic activity against autologous melanoma cells. Based on these observations and to further characterize DP T cells, both populations were compared at the transcriptional level. Our results revealed the overexpression of the IL-9 receptor (IL-9R) by DP T cells and prompted us to investigate the impact of IL-9 on their biology. We show that IL-9 favors DP T-cell survival by protecting them from apoptosis and by promoting their proliferation. In addition, IL-9 enhances their ability to produce cytokines and increased their levels of granzyme B/perforin as well as degranulation capacity, leading to a strengthened cytotoxic activity against melanoma cells. Taken together, the IL-9R high DP T-cell population could be a new preferential target for IL-9, which could take part in their retention within the melanoma infiltrate while also favoring their anti-tumor activity. More generally, our results extend the pleiotropic effects of IL-9 to IL-9R-expressing intra-tumor T cells, which could further potentiate anti-tumor immune responses. Keywords: CD4 + CD8 + double-positive T lymphocyte r IL-9R r IL-9 r Melanoma r TIL Additional supporting information may be found in the online version of this article at the publisher's web-site

International audience; Macrophages orchestrate the immune response via the polarization of CD4+ T helper (Th) cells. Different subsets of macrophages with distinct phenotypes, and sometimes opposite functions, have been described. M-CSF and IL-34 induce the differentiation of monocytes into IL-10high IL-12low immunoregulatory macrophages, which are similar to tumor-associated macrophages (TAMs) in ovarian cancer. In this study, we evaluated the capacity of human macrophages induced in the presence of M-CSF (M-CSF macrophages) or IL-34 (IL-34 macrophages) and ovarian cancer TAMs to modulate the phenotype of human CD4+ T cells. Taken together, our results show that M-CSF-, IL-34 macrophages, and TAMs switch non-Th17 committed memory CD4+ T cells into conventional CCR4+ CCR6+ CD161+ Th17 cells, expressing or not IFN-gamma. Contrary, the pro-inflammatory GM-CSF macrophages promote Th1 cells. The polarization of memory T cells into Th17 cells is mediated via membrane IL-1α (mIL-1α), which is constitutively expressed by M-CSF-, IL-34 macrophages, and TAMs. This study elucidates a new mechanism that allows macrophages to maintain locally restrained and smoldering inflammation, which is required in angiogenesis and metastasis.

International audience; We recently showed that the infusion of tumor infiltrating lymphocytes specific for the MELOE-1 antigen was associated with a prolonged relapse-free survival for HLA-A2 1 melanoma patients who received tumor infiltrating lymphocytes therapy. Here, we characterized the MELOE-1/A2-specific T-cell repertoire in healthy donors and melanoma patients to further support an immunotherapy targeting this epitope. Using tetramer enrichment followed by multicolor staining, we found that MELOE-1-specific T cells were present in the blood of healthy donors and patients at similar frequencies (around 1 in 1 Â 10 5 CD8 1 cells). These cells mainly displayed a naïve phenotype in 4/6 healthy donors and 3/6 patients, whereas high proportions of memory cells were observed in the remaining individuals of both groups. There was a recurrent usage of the Va12.1 chain for 17/18 MELOE-1-specific T-cell clones derived from healthy donors or patients, associated with diverse Vb chains and V(D)J junctional sequences. All clones derived from melanoma patients (9/9) were reactive against the MELOE-1 36-44 peptide and against HLA-A2 1 melanoma cell lines. This study documents the existence of a large TCR repertoire specific for the MELOE-1/A2 epitope and its capacity to give rise to antitumor CTL that supports the development of immunotherapies targeting this epitope.