Search

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; Acute myeloid leukemia (AML) cells are killed by allogeneic NK cells. However, autologous NK cells from AML patients express decreased levels of activating receptors, and show reduced cytotoxicity. Here, we investigated how interactions between NK and AML cells might cause loss of NK-cell activity in patients. Our results show that AML cell lines and primary blasts alter the NK-cell phenotype, reducing their cytotoxic potential upon prolonged contact. Downregulation of NK-cell-activating receptors was contactdependent and correlated with conjugate formation. Time-lapse imaging of HL60 AML cell line and NK-cell interactions showed a high proportion of noncytolytic contacts. Studies of NK-cell immunological synapses revealed a defect in lytic synapse formation. Namely, despite correct F-actin and LFA-1 recruitment, polarization of lytic granules toward primary blasts or AML cell lines was reduced. The NK-AML cell line synapses showed impairment of CD3ζ recruitment. Attempts to correct these synapse defects by cytokine stimulation of NK cells improved conjugate formation, but not granule polarization. Pretreatment of AML cell lines with the immunomodulating molecule lenalidomide significantly enhanced granule polarization. We speculate that combining immunomodulatory drugs and cytokines could increase AML cell sensitivity to autologous NK cells and reinforce the activity of allogeneic NK cells in adoptive immunotherapy.

International audience; Fifty-nine tumor-infiltrating lymphocyte (TIL) cultures established from melanoma-invaded lymph nodes were screened for recognition of 28 melanoma-associated antigens (MAA) in association with 31 HLA molecules. Twenty-three (39%) TIL lines reacted to at least one mel-anoma antigen. Melanosomal proteins were recognized by 19 TIL populations and the most prominent responses against these proteins were directed against Melan-A/MART-1 (mainly in association with HLA-A*0201) and gp100 (in association with diverse HLA contexts). Ten TIL populations reacted against 10 tumor-specific antigens, in association with 8 different HLA molecules. HLA-A*0201 and B*3501-restricted responses were the most frequent with, respectively, 17 and 7 responses directed against 5 distinct antigens. Unexpectedly, the recognition by TIL of different MAA was frequently restricted by a single HLA in individual tumors, and there was no evidence for the existence of dominant MAA epitopes between tumors, except for Melan-A/MART-1 antigen. This analysis also led to the detection of 21 new HLA-peptide complexes recognized by melanoma TIL. This study, which is to our knowledge the most comprehensive analysis of TIL specificity to tumor antigens, has several implications for the design of immunotherapeutic strategies based on immunization against selected tumor epitopes.

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.

Persistence of memory CD8(+) T cells is known to be largely controlled by common gamma chain cytokines, such as IL-2, IL-7 and IL-15. However, other molecules may be involved in this phenomenon. We show here that TLR2(-/-) mice have a decreased frequency of memory phenotype CD8(+) T cells when compared with WT mice. This prompted us to investigate the role of TLR2 in the homeostasis of memory CD8(+) T cells. We describe here a new TLR2-dependent mechanism which, in the absence of specific antigen, directly controls memory CD8(+) T-cell proliferation and IFN-gamma secretion. We demonstrate that TLR2 engagement on memory CD8(+) T cells increases their proliferation and expansion induced by IL-7 both in vitro and in vivo. We also show that TLR2 ligands act in synergy with IL-2 to induce IFN-gamma secretion in vitro. Both conclusions are obtained with spontaneously arising memory phenotype and antigen-specific memory CD8(+) T cells. Altogether, our data support the idea that continuous TLR2 signaling in response to microbial stimuli or endogenous danger signals might directly contribute to the maintenance of the diversity memory CD8(+) T cells in the organism.