Double Positive CD4CD8 αβ T Cells: A New Tumor-Reactive Population in Human Melanomas

Abstract

BackgroundDouble positive (DP) CD4CD8 Tαβ 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 Tαβ 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 FindingsWe 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-α 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/SignificanceIn 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.

IL‐9 promotes the survival and function of human melanoma‐infiltrating CD4+CD8+ double‐positive T cells

“…Simultaneous quantification of a panel of 13 cytokines was performed on supernatants obtained from eight DP T-cell lines preincubated or not with IL-9 (20 ng/mL) for 24 h before anti-CD3 mAb activation (6 h). As described in our previous findings [31], DP T cells were characterized by their mixed Th1/Th2 cytokine profile with notably high production of TNF-α, IL-13, IL-5, IFN-γ, IL-2 and IL-4 ( Table 1). Marginal production of IL-1β, IL-17A, IL-10 was also detected in this assay.…”

“…To date, the lack of unequivocal studies prevents the establishment of a consensus regarding DP T-cell origin, phenotype and function for a given pathological context. Thus, DP T cells require individual consideration on a case-by-case basis.In cancer, DP T cells have been initially reported in lymphomas as cutaneous T-cell lymphomas [26][27][28] and nodular lymphocyte predominant Hodgkin lymphoma [29] where they were described as a CD4 high CD8 low DP T-cell population with cytotoxic activity [26].Besides, we documented the presence of CD4 low CD8αβ high DP T cells at a high frequency, among tumor-infiltrating lymphocytes (TILs) of several solid human tumors (breast carcinomas, melanomas, and colorectal carcinomas) [25,30,31]. Moreover, the prevalence of DP T cells in distant cutaneous metastasis was significantly higher (p < 0.05) than in lymph node metastasis and even higher (p < 0.01) than in blood from patients or healthy donors, suggesting an association between DP T-cell frequency and both tumor microenvironment and cancer progression.…”

“…Moreover, the prevalence of DP T cells in distant cutaneous metastasis was significantly higher (p < 0.05) than in lymph node metastasis and even higher (p < 0.01) than in blood from patients or healthy donors, suggesting an association between DP T-cell frequency and both tumor microenvironment and cancer progression. Interestingly, about 15% of polyclonal melanoma-infiltrating DP T cells were reactive against autologous tumor cells, reinforcing their physiological relevance in cancer [31].…”

“…Moreover, the prevalence of DP T cells in distant cutaneous metastasis was significantly higher (p < 0.05) than in lymph node metastasis and even higher (p < 0.01) than in blood from patients or healthy donors, suggesting an association between DP T-cell frequency and both tumor microenvironment and cancer progression. Interestingly, about 15% of polyclonal melanoma-infiltrating DP T cells were reactive against autologous tumor cells, reinforcing their physiological relevance in cancer [31].Intra-melanoma DP T cells recognize tumor cells in an HLA-I restricted context and in a CD8 dependent way, and therefore seems to be close to the conventional effector SP CD8 T-cell lineage although they differ from SP CD8 + T cells by their weak cytotoxic activity. Thus, in order to extensively characterize melanomainfiltrating DP T cells, we performed a transcriptome analysis in comparison to autologous SP CD8 + T lymphocytes.…”

“…Besides, we documented the presence of CD4 low CD8αβ high DP T cells at a high frequency, among tumor-infiltrating lymphocytes (TILs) of several solid human tumors (breast carcinomas, melanomas, and colorectal carcinomas) [25,30,31]. Moreover, the prevalence of DP T cells in distant cutaneous metastasis was significantly higher (p < 0.05) than in lymph node metastasis and even higher (p < 0.01) than in blood from patients or healthy donors, suggesting an association between DP T-cell frequency and both tumor microenvironment and cancer progression.…”