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Recently, the inhibitory CD94/NKG2A receptor has joined the group of immune checkpoints (ICs) and its expression has been documented in NK cells and CD8 + T lymphocytes in several cancers and some infectious diseases. In colorectal cancer (CRC), we previously reported that NKG2A + tumor-infiltrating lymphocytes (TILs) are predominantly CD8 + αβ T cells and that CD94 overexpression and/or its ligand HLA-E were associated with a poor prognosis. This study aimed to thoroughly characterize the NKG2A + CD8 + TIL subpopulation and document the impact of NKG2A on anti-tumor responses in CRC. Our findings highlight new features of this subpopulation: (i) enrichment in colorectal tumors compared to paired normal colonic mucosa, (ii) their character as tissue-resident T cells and their majority terminal exhaustion status, (iii) co-expression of other ICs delineating two subgroups differing mainly in the level of NKG2A expression and the presence of PD-1, (iv) high functional avidity despite reduced proliferative capacity and finally (v) inhibition of anti-tumor reactivity that is overcome by blocking NKG2A. From a clinical point of view, these results open a promising alternative for immunotherapies based on NKG2A blockade in CRC, which could be performed alone or in combination with other IC inhibitors, adoptive cell transfer or therapeutic vaccination., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2022 The Author(s). Published with license by Taylor & Francis Group, LLC.)

Background: Double positive (DP) CD4CD8 Talphabeta cells have been reported in normal individuals as well as in different pathological conditions including inflammatory diseases, viral infections and cancer, but their function remains to be elucidated. We recently reported the increased frequency of DP Talphabeta cells in human breast pleural effusions. This manuscript addresses the question of the existence and above all the role of this non-conventional DP sub-population among tumor associated lymphocytes in melanomas., Methodology/principal Findings: We analyzed the intratumoral cell infiltrate in solid metastasis (n = 6) and tumor invaded lymph nodes (n = 26) samples from melanomas patients by multiparametric cytometry. Here we documented for the first time significant increased frequency of DP T cells in about 60% of melanoma tumors compared to blood samples. Interestingly, a high proportion of these cells produced TNF-alpha in response to autologous melanoma cell lines. Besides, they are characterized by a unique cytokine profile corresponding to higher secretion of IL-13, IL-4 and IL-5 than simple positive T cells. In deep analysis, we derived a representative tumor-reactive DP T cell clone from a melanoma patient's invaded lymph node. This clone was restricted by HLA-A*2402 and recognized both autologous and allogeneic tumor cells of various origins as well as normal cells, suggesting that the target antigen was a ubiquitous self antigen. However, this DP T cell clone failed to kill HLA-A*2402 EBV-transformed B cells, probably due to the constitutive expression of immunoproteasome by these cells., Conclusions/significance: In conclusion, we can postulate that, according to their broad tumor reactivity and to their original cytokine profile, the tumor associated DP T cells could participate in immune responses to tumors in vivo. Therefore, the presence of these cells and their role will be crucial to address in cancer patients, especially in the context of immunotherapies.

Breast cancer remains a leading cause of cancer-related death within the female population. Immunotherapy is expected to provide additional therapeutic benefits but has met so far limited success. This may be due in part to the poor understanding of immune responses to breast cancer. Although CD4(+) and CD8(+) T lymphocytes infiltrate these tumors, the phenotype and functions of these cells remain ill defined. This study was designed to investigate further about these questions, taking advantage of multiparameter flow cytometry on lymphocytes derived from peripheral blood, solid tumors, metastatic lymph nodes and pleural effusions samples of patients with breast cancer. Results showed that, in addition to conventional CD4(+) and CD8(+) alphabeta T cells, individual tumors and most pleural effusions contained significant fractions of unconventional double positive (DP) CD4(+)CD8(+) alphabeta T cells. These DP T cells displayed the phenotype and cytotoxic potential of effector/memory activated CD8(+) T cells but differed essentially from these cells by a high production of IL-5 and IL-13. The increased frequency of DP T cells in advanced breast cancer and their high lytic potential and original cytokine profile suggest that this T-cell subset may play a specific role in the regulation of immune responses to human breast cancer., (Copyright 2009 UICC.)