Distribution, characterization, and induction of CD8+ regulatory T cells and IL-17-producing CD8+ T cells in nasopharyngeal carcinoma

EBV-induced T-cell responses in EBV-specific and nonspecific cancers

Epstein-Barr virus (EBV) is a ubiquitous human tumor virus associated with various malignancies, including B-lymphoma, NK and T-lymphoma, and epithelial carcinoma. It infects B lymphocytes and epithelial cells within the oropharynx and establishes persistent infection in memory B cells. With a balanced virus-host interaction, most individuals carry EBV asymptomatically because of the lifelong surveillance by T cell immunity against EBV. A stable anti-EBV T cell repertoire is maintained in memory at high frequency in the blood throughout persistent EBV infection. Patients with impaired T cell immunity are more likely to develop life-threatening lymphoproliferative disorders, highlighting the critical role of T cells in achieving the EBV-host balance. Recent studies reveal that the EBV protein, LMP1, triggers robust T-cell responses against multiple tumor-associated antigens (TAAs) in B cells. Additionally, EBV-specific T cells have been identified in EBV-unrelated cancers, raising questions about their role in antitumor immunity. Herein, we summarize T-cell responses in EBV-related cancers, considering latency patterns, host immune status, and factors like human leukocyte antigen (HLA) susceptibility, which may affect immune outcomes. We discuss EBV-induced TAA-specific T cell responses and explore the potential roles of EBV-specific T cell subsets in tumor microenvironments. We also describe T-cell immunotherapy strategies that harness EBV antigens, ranging from EBV-specific T cells to T cell receptor-engineered T cells. Lastly, we discuss the involvement of γδ T-cells in EBV infection and associated diseases, aiming to elucidate the comprehensive interplay between EBV and T-cell immunity.

"To be or not to Be": Regulatory T cells in melanoma

In spite of progresses in the therapy of different malignancies, melanoma still remains as one of lethal types of skin tumor. Melanoma is almost easily treatable by surgery alone with higher overall survival rates when it is diagnosed at early stages. However, survival rates are decreased remarkably upon survival if the tumor is progressed to advanced metastatic stages. Immunotherapeutics have been prosperous in the development of anti-tumor responses in patients with melanoma through promotion of the tumor-specific effector T cells in vivo; nonetheless, suitable clinical outcomes have not been satisfactory. One of the underlying causes of the unfavorable clinical outcomes might stem from adverse effects of regulatory T (Treg) cell, which is a prominent mechanism of tumor cells to escape from tumor-specific immune responses. Evidence shows that a poor prognosis and low survival rate in patients with melanoma can be attributed to a higher Treg cell number and function in these subjects. As a result, to promote melanoma-specific anti-tumor responses, depletion of Treg cells appears to be a promising approach; even though the clinical efficacy of different approaches to attain appropriate Treg cell depletion has been inconsistent. Here in this review, the main purpose is to assess the role of Treg cells in the initiation and perpetuation of melanoma and to discuss effective strategies for Treg cell modulation with the aim of melanoma therapy.

Role of immune-inflamed phenotype in the prognosis of hypopharyngeal carcinoma following primary surgery

BACKGROUND

The immune profile in primary resected hypopharyngeal squamous cell carcinoma (HPSCC) and its prognostic value remain to be defined.

METHODS

We enrolled 100 patients with HPSCC underwent primary surgical resection at our department. HPSCC samples were examined using immunohistochemistry for the expressions of CD8, Foxp3, CD163, CD66B, programmed death ligand-1 (PD-L1), and interferon (IFN)-γ. The immune pattern of the tumor microenvironment (TME) was discriminated into inflamed and non-inflamed tumors based on the presence or absence of parenchymal CD8⁺ T cells.

RESULTS

We found that 74% of HPSCC cases in our cohort were characterized by an immune-inflamed TME. Immune-inflamed patterns demonstrated an inferior survival with a significantly increased density of CD163⁺ tumor-associated macrophages and Foxp3⁺ regulatory T cells. Additionally, the inflamed tumor showed increased expression of PD-L1, without IFN-γ upregulation.

CONCLUSIONS

The immune-inflamed pattern is the predominant preexisting immune phenotype in HPSCC and demonstrates immunosuppressive immune cell recruitment.

Circulating CD8+CD122+ T cells as a prognostic indicator of pancreatic cancer

Purpose

The distribution of tissue infiltrating lymphocytes has been shown to affect the prognosis of patients with pancreatic cancer in some previous studies. However, the role of peripheral lymphocytes in pancreatic cancer remains debated. The purpose of this study was to analyze the peripheral subtypes of T lymphocytes, and establish their association with the prognosis of patients with pancreatic cancer.

Methods

Blood and tissue samples were collected from patients with metastatic pancreatic cancer (n = 54), resectable pancreatic cancer (n = 12), and benign pancreatic cysts (n = 52) between April 2019 and January 2022 and analyzed.

Results

Patients with metastatic pancreatic cancer had a larger proportion of both tumor-suppressive and tumor-promoting cells than those with benign pancreatic cysts. In addition, the proportion of peripheral CD4+ T cells positively correlated with the survival of patients with metastatic pancreatic cancer, and the proportion of peripheral CD8+CD122+ T cells was associated with early mortality (< 90 days). After chemotherapy, CD8+CD122+ T cells decreased in patients who had a partial response or stable disease. Moreover, by analyzing resected specimens, we first proved that the existence of CD8+CD122+ T cells in a tumor microenvironment (TME) depends on their proportion in peripheral blood.

Conclusion

Circulating CD8+CD122+ T cells can be a prognostic indicator in patients with pancreatic cancer.

Nasopharyngeal Carcinoma and Its Microenvironment: Past, Current, and Future Perspectives

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy that raises public health concerns in endemic countries. Despite breakthroughs in therapeutic strategies, late diagnosis and drug resistance often lead to unsatisfactory clinical outcomes in NPC patients. The tumor microenvironment (TME) is a complex niche consisting of tumor-associated cells, such as fibroblasts, endothelial cells, leukocytes, that influences tumor initiation, progression, invasion, and metastasis. Cells in the TME communicate through various mechanisms, of note, exosomes, ligand-receptor interactions, cytokines and chemokines are active players in the construction of TME, characterized by an abundance of immune infiltrates with suppressed immune activities. The NPC microenvironment serves as a target-rich niche for the discovery of potential promising predictive or diagnostic biomarkers and the development of therapeutic strategies. Thus, huge efforts have been made to exploit the role of the NPC microenvironment. The whole picture of the NPC microenvironment remains to be portrayed to understand the mechanisms underlying tumor biology and implement research into clinical practice. The current review discusses the recent insights into the role of TME in the development and progression of NPC which results in different clinical outcomes of patients. Clinical interventions with the use of TME components as potential biomarkers or therapeutic targets, their challenges, and future perspectives will be introduced. This review anticipates to provide insights to the researchers for future preclinical, translational and clinical research on the NPC microenvironment.

Epstein–Barr Virus Epithelial Cancers—A Comprehensive Understanding to Drive Novel Therapies

Epstein–Barr virus (EBV) is a ubiquitous oncovirus associated with specific epithelial and lymphoid cancers. Among the epithelial cancers, nasopharyngeal carcinoma (NPC), lymphoepithelioma-like carcinoma (LELC), and EBV-associated gastric cancers (EBVaGC) are the most common. The role of EBV in the pathogenesis of NPC and in the modulation of its tumour immune microenvironment (TIME) has been increasingly well described. Much less is known about the pathogenesis and tumour–microenvironment interactions in other EBV-associated epithelial cancers. Despite the expression of EBV-related viral oncoproteins and a generally immune-inflamed cancer subtype, EBV-associated epithelial cancers have limited systemic therapeutic options beyond conventional chemotherapy. Immune checkpoint inhibitors are effective only in a minority of these patients and even less efficacious with molecular targeting drugs. Here, we examine the key similarities and differences of NPC, LELC, and EBVaGC and comprehensively describe the clinical, pathological, and molecular characteristics of these cancers. A deeper comparative understanding of these EBV-driven cancers can potentially uncover targets in the tumour, TIME, and stroma, which may guide future drug development and cast light on resistance to immunotherapy.

Necrosis Factor-α (TNF-α) and the Presence of Macrophage M2 and T Regulatory Cells in Nasopharyngeal Carcinoma

OBJECTIVE

To investigate the correlation between TLR3 and pro-inflammatory cytokines (TNFα, IL6) expression with the distribution of macrophage M2 and Treg on Epstein Barr virus-encoded RNAs (EBER+) nasopharyngeal carcinoma (NPC) tissues.

METHODS

A total of 23 FFPE NPC tissue samples were obtained from patients in Dr. Sardjito General Hospital, Yogyakarta, Indonesia in 2008-2010, which expressed EBER was collected. The expressions of TLR3, TNFα, and IL6 were examined using immunofluorescence assay. The distribution of macrophage M2 and Treg were examined by immunohistochemistry with anti-CD163 and -FOXP3 antibodies, respectively. The quantification of fluorescence intensity was analyzed by the RGB space method using ImageJ software. The M2 interpretation was done by the eyeballing method and the M2 scores were divided into 0 (negative), 1 (scant), 2 (focal), 3 (abundant). The average number of Treg FOXP3+ cells in five high power fields was counted. The relationship between variables were tested by the Spearman correlation test, and the coefficient correlation was used to see the correlation between variables.

RESULTS

All EBER+ NPC specimens showed TLR3 expression intracellularly. The expression of TNFα could be observed in the cell membranes and secreted extracellularly, while IL6 was secreted to the extracellular area. The expression of TNFα was two times higher than IL6. Most specimens showed low M2 score (56.52%) and high Treg (52.17%). A positive correlation was found between TLR3 and IL6 (12.9%). TNFα was positively correlated with the M2 distribution of 13.7% and Treg distribution of 12.9%, while the rest were explained by other factors.

CONCLUSION

TNFα has a positive correlation with M2 and Treg distribution,but mostly through a different mechanism other than EBER-TLR3 interaction. Possibly, other pro-inflammatory and anti-inflammatory cytokines are involved in the formation of the NPC microenvironment, especially related to the presence of M2 and Treg, which provide immunosuppressive effects in NPC tumors. 
.

Targeting Immune Modulators in Glioma While Avoiding Autoimmune Conditions

Communication signals and signaling pathways are often studied in different physiological systems. However, it has become abundantly clear that the immune system is not self-regulated, but functions in close association with the nervous system. The neural-immune interface is complex; its balance determines cancer progression, as well as autoimmune disorders. Immunotherapy remains a promising approach in the context of glioblastoma multiforme (GBM). The primary obstacle to finding effective therapies is the potent immunosuppression induced by GBM. Anti-inflammatory cytokines, induction of regulatory T cells, and the expression of immune checkpoint molecules are the key mediators for immunosuppression in the tumor microenvironment. Immune checkpoint molecules are ligand-receptor pairs that exert inhibitory or stimulatory effects on immune responses. In the past decade, they have been extensively studied in preclinical and clinical trials in diseases such as cancer or autoimmune diseases in which the immune system has failed to maintain homeostasis. In this review, we will discuss promising immune-modulatory targets that are in the focus of current clinical research in glioblastoma, but are also in the precarious position of potentially becoming starting points for the development of autoimmune diseases like multiple sclerosis.

The Roles of CD8+ T Cell Subsets in Antitumor Immunity

Effector CD8⁺ T cells are typically thought to be a homogenous group of cytotoxic cells that produce interferon-(IFN) γ. However, recent findings have challenged this notion because multiple subsets of CD8⁺ T cells have been described, each with distinct effector functions and cytotoxic potential. These subsets, referred to as the Tc subsets, have also been detected in tumor microenvironments (TMEs), where they potentially influence the antitumor response and patient outcomes. In this review, we highlight the prevalence and roles of Tc subsets in the TME. We also discuss their therapeutic applications in the context of adoptive immunotherapy to treat cancer.

IL-17-Producing Cells in Tumor Immunity: Friends or Foes?

IL-17 is produced by RAR-related orphan receptor gamma t (RORγt)-expressing cells including Th17 cells, subsets of γδT cells and innate lymphoid cells (ILCs). The biological significance of IL-17-producing cells is well-studied in contexts of inflammation, autoimmunity and host defense against infection. While most of available studies in tumor immunity mainly focused on the role of T-bet-expressing cells, including cytotoxic CD8⁺ T cells and NK cells, and their exhaustion status, the role of IL-17-producing cells remains poorly understood. While IL-17-producing T-cells were shown to be anti-tumorigenic in adoptive T-cell therapy settings, mice deficient in type 17 genes suggest a protumorigenic potential of IL-17-producing cells. This review discusses the features of IL-17-producing cells, of both lymphocytic and myeloid origins, as well as their suggested pro- and/or anti-tumorigenic functions in an organ-dependent context. Potential therapeutic approaches targeting these cells in the tumor microenvironment will also be discussed.

Expression and clinical significance of programmed death ligand 1 in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) has the highest incidence of all types of head and neck cancer in China. The present study aimed to investigate the association between the expression of programmed death ligand 1 (PD-L1) in NPC tissues and clinicopathological features, as well the outcomes for NPC patients. In addition, the association between tissue expression of PD-L1 and immune components in peripheral blood was assessed. The expression of PD-L1 was determined by immunohistochemistry, while immune indexes were determined by ELISA and flow cytometry. The positive expression rate of PD-L1 in NPC patients was 29.2%, and the PD-L1 expression levels were associated with distant metastasis (P=0.010) and the T-stage of the primary tumor (P=0.032). The expression of PD-L1 was associated with the distant metastasis-free survival of NPC patients (P=0.006). In addition, a statistically significant association of PD-L1 expression with Epstein-Barr virus viral capsid antigen IgA (EBV VCA-IgA; P=0.046) and with CD3^-CD19⁺ cells (P=0.014) was identified. These results indicated that PD-L1 may be a potential prognostic biomarker for NPC patients, and that EBV VCA-IgA and CD3^-CD19⁺ cells may be useful for predicting PD-L1 expression when its levels cannot be detected due to the lack of a tumor tissue sample.

Interplay of Viral Infection, Host Cell Factors and Tumor Microenvironment in the Pathogenesis of Nasopharyngeal Carcinoma

Undifferentiated nasopharyngeal carcinoma (NPC) is strongly associated with Epstein-Barr virus (EBV) infection. In addition, heavy infiltration of leukocytes is a common characteristic of EBV-associated NPC. It has long been suggested that substantial and interactive impacts between cancer and stromal cells create a tumor microenvironment (TME) to promote tumorigenesis. The coexistence of tumor-infiltrating lymphocytes with EBV-infected NPC cells represents a distinct TME which supports immune evasion and cancer development from the early phase of EBV infection. Intracellularly, EBV-encoded viral products alter host cell signaling to facilitate tumor development and progression. Intercellularly, EBV-infected cancer cells communicate with stromal cells through secretion of cytokines and chemokines, or via release of tumor exosomes, to repress immune surveillance and enhance metastasis. Although high expression of miR-BARTs has been detected in NPC patients, contributions of these more recently discovered viral products to the establishment of TME are still vaguely defined. Further investigations are needed to delineate the mechanistic linkage of the interplay between viral and host factors, especially in relation to TME, which can be harnessed in future therapeutic strategies.

TGF-β1 contributes to CD8+ Treg induction through p38 MAPK signaling in ovarian cancer microenvironment

CD8⁺ regulatory T cells (Tregs) contribute to cancer progression and immune evasion. We previously reported that CD8⁺ Tregs could be induced in vitro by co-culture of CD8⁺ T cells with the OC cell lines SKOV3/A2780. Here, we described the role of TGF-β1 in CD8⁺ Treg induction by the OC microenvironment. OC patients expressed high levels of TGF-β1, as did the co-culture supernatant from CD8⁺ T cells and SKOV3. Additionally, TGF-β1 levels were positively correlated with CD8⁺ Treg percentages in OC. Neutralization experiments, cytokine studies and proliferation assays revealed that the in vitro-induced CD8⁺Tregs depended at least partially on up-regulated expression of TGF-β1 to exert their suppressive function. CD8⁺ T cells cultured with SKOV3 exhibited marked activation of p38 MAPK than CD8⁺ T cells cultured alone, which could be inhibited by TGF-β1-neutralizing antibody. Moreover, the p38 specific inhibitor SB203580 dose-dependently blocked the TGF-β1 activated conversion of CD8⁺ T cells into CD8⁺ Tregs. These data suggested that in vitro-induction of CD8⁺ Tregs depended in part on TGF-β1 activation of p38 MAPK signaling. Therefore, p38 MAPK could be a therapeutic target in OC anti-tumor immunotherapy.

The tumor microenvironment: Thousand obstacles for effector T cells

The immune system is endowed with the capability to recognize and destroy transformed cells, but even in the presence of an immune infiltrate many tumors do progress. In the last decades new discoveries have shed light into (some of) the underlying mechanisms. Immune effector cells are not only under the influence of immune suppressive cell subsets, but also intrinsically regulated by immune check point molecules that under physiological condition avoid attach of healthy tissue. Moreover, tumor cells are modifying the surrounding microenvironment through secretion of immune modulators as well as via their own metabolism, thus further impairing the development of immune effector functions. Different approaches are currently being evaluated in the clinic to overcome those regulatory mechanisms and to unleash effector T cells.

Do tumor-infiltrating lymphocytes really indicate favorable prognosis in epithelial ovarian cancer?

OBJECTIVE

The aim of this study is to evaluate the impact of lymphocyte infiltration on prognostic parameters, recurrence and survival in ovarian cancer.

STUDY DESIGN

Sixty-two patients who were primarily operated for epithelial ovarian carcinoma between 1997 and 2008 were included. CD3, CD4, CD8, CD20 and FoxP3 expressions were evaluated immunohistochemically on sections obtained from paraffin-embedded tissues.

RESULTS

Median follow up was 87 months. In whole cohort, CD3+ and CD8+ T lymphocyte infiltrations were significantly higher in patients with high-grade tumors, advanced stage tumors and the patients with omental metastasis (for CD3 p=0.0001, p=0.029, p=0.016; for CD8 p=0.044, p=0.002, p=0.046, respectively). DFS was significantly lower among patients with CD8+ T lymphocytes with regard to patients who did not have CD8+ T lymphocyte infiltration (p=0.028). In univariate analysis, presence of CD8 cytotoxic T lymphocyte infiltration (p=0.03), stage (0.0001), tumor grade (p=0.007), omental metastasis (p=0.0001) and lymph node metastasis (p=0.0001) were significant risk factors for recurrence. But in multivariate analysis, only stage [HR: 116.6 (95% CI: 13.09-1039.45) (p=0.0001)] was found as an independent risk factor for recurrence.

CONCLUSION

CD3+ and CD8+ T lymphocyte infiltrations were related with advanced stage, high-grade tumor and the omental metastasis in ovarian cancer. DFS was significantly shorter in patients with CD8+ T lymphocyte infiltration. CD3+ and CD8+ T lymphocyte infiltrations were related with poor prognosis in ovarian cancer.

Gene expression profiling of CD8+ T cells induced by ovarian cancer cells suggests a possible mechanism for CD8+ Treg cell production

OBJECTIVES

The aim of this study was to investigate a possible mechanism of CD8⁺ regulatory T-cell (Treg) production in an ovarian cancer (OC) microenvironment.

MATERIALS AND METHODS

Agilent microarray was used to detect changes in gene expression between CD8⁺ T cells cultured with and without the SKOV3 ovarian adenocarcinoma cell line. QRT-PCR was performed to determine glycolysis gene expression in CD8⁺ T cells from a transwell culturing system and OC patients. We also detected protein levels of glycolysis-related genes using Western blot analysis.

RESULTS

Comparing gene expression profiles revealed significant differences in expression levels of 1420 genes, of which 246 were up-regulated and 1174 were down-regulated. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis indicated that biological processes altered in CD8⁺ Treg are particularly associated with energy metabolism. CD8⁺ Treg cells induced by co-culture with SKOV3 had lower glycolysis gene expression compared to CD8⁺ T cells cultured alone. Glycolysis gene expression was also decreased in the CD8⁺ T cells of OC patients.

CONCLUSIONS

These findings provide a comprehensive bioinformatics analysis of DEGs in CD8⁺ T cells cultured with and without SKOV3 and suggests that metabolic processes may be a possible mechanism for CD8⁺ Treg induction.

Interleukin-17 acts as double-edged sword in anti-tumor immunity and tumorigenesis

Interleukin-17 (IL-17), a proinflammatory cytokine, mainly produced by Th17 cells, participates in both innate and adaptive immune responses and is involved in various diseases, including infectious diseases, autoimmune disorders and cancer. Emerging evidence indicates that IL-17 not only has an oncogenic role in tumorigenesis by regulating tumor angiogenesis and enhancing tumor immune evasion but also exerts anti-tumor functions by enhancing natural killer (NK) cells and cytotoxic T lymphocytes (CTLs) activation and through the recruitment of neutrophils, NK cells and CD4⁺ and CD8⁺ T cells to tumor tissue. In this review, we provide an overview on the basic biology of IL-17 and recent findings regarding its enigmatic double-edged features in tumorigenesis, with special attention to the roles of IL-17 produced by tumor cells interacting with other factors in the tumor microenvironment.

Naive Treg-like CCR7(+) mononuclear cells indicate unfavorable prognosis in hepatocellular carcinoma

Chemokine receptor-like 1 (CCRL1) has the potential in creating a low level of CCL19 and CCL21 to hinder CCR7(+) cell tracking to tumor tissue. Previously, we found a tumor suppressive role of CCRL1 by impairing CCR7-related chemotaxis of tumor cells in human hepatocellular carcinoma (HCC). Here, we reported a contribution of CCR7(+) mononuclear cells in the tumor microenvironment to the progression of disease. Immunohistochemistry was used to investigate the distribution and clinical significance of CCR7(+) cells in a cohort of 240 HCC patients. Furthermore, the phenotype, composition, and functional status of CCR7(+) cells were determined by flow cytometry, immunofluorescence, and in vitro co-culture assays. We found that CCR7(+) mononuclear cells were dispersed around tumor tissue and negatively related to tumoral expression of CCRL1 (P < 0.001, r = 0.391). High density of CCR7(+) mononuclear cells positively correlated with the absence of tumor capsule, vascular invasion, and poor differentiation (P < 0.05). Survival analyses revealed that increased number of CCR7(+) mononuclear cells was significantly associated with worse survival and increased recurrence. We found that CCR7(+) mononuclear cells featured a naive Treg-like phenotype (CD45RA(+)CD25(+)FOXP3(+)) and possessed tumor-promoting potential by producing TGF-β1. Moreover, CCR7(+) cells were also composed of several immunocytes, a third of which were CD8(+) T cells. CCR7(+) Treg-like cells facilitate tumor growth and indicate unfavorable prognosis in HCC patients, but fortunately, their tracking to tumor tissue is under the control of CCRL1.

T-Cell Responses to EBV

Epstein-Barr virus (EBV) is arguably one of the most successful pathogens of humans, persistently infecting over ninety percent of the world's population. Despite this high frequency of carriage, the virus causes apparently few adverse effects in the vast majority of infected individuals. Nevertheless, the potent growth transforming ability of EBV means the virus has the potential to cause malignancies in infected individuals. Indeed, EBV is thought to cause 1% of human malignancies, equating to 200,000 malignancies each year. A clear factor as to why virus-induced disease is relatively infrequent in healthy infected individuals is the presence of a potent immune response to EBV, in particular, that mediated by T cells. Thus, patient groups with immunodeficiencies or whose cellular immune response is suppressed have much higher frequencies of EBV-induced disease and, in at least some cases, these diseases can be controlled by restoration of the T-cell compartment. In this chapter, we will primarily review the role the αβ subset of T cells in the control of EBV in healthy and diseased individuals.

Characterization of tumor infiltrating lymphocytes in paired primary and metastatic renal cell carcinoma specimens

Renal cell carcinoma (RCC) is one of the most chemo- and radio-resistant malignancies, with poor associated patient survival if the disease metastasizes. With recent advances in immunotherapy, particularly with PD-1/PD-L1 blockade, outcomes are improving, but a substantial subset of patients does not respond to the new agents. Identifying such patients and improving the therapeutic ratio has been a challenge, although much effort has been made to study PD-1/PD-L1 status in pre-treatment tumor. However, tumor infiltrating lymphocyte (TIL) content might also be predictive of response, and our goal was to characterize TIL content and PD-L1 expression in RCC tumors from various anatomic sites. Utilizing a quantitative immunofluorescence technique, TIL subsets were examined in matched primary and metastatic specimens. In metastatic specimens, we found an association between low CD8+ to Foxp3+ T-cell ratios and high levels of PD-L1. High PD-L1-expressing metastases were also found to be associated with tumors that were high in both CD4+ and Foxp3+ T-cell content. Taken together these results provide the basis for combining agents that target the PD-1/PD-L1 pathway with agonist of immune activation, particularly in treating RCC metastases with unfavorable tumor characteristics and microenvironment. In addition, CD8+ TIL density and CD8:Foxp3 T-cell ratio were higher in primary than metastatic specimens, supporting the need to assess distant sites for predictive biomarkers when treating disseminated disease.

Analysis of CD8+ Treg cells in patients with ovarian cancer: a possible mechanism for immune impairment

Regulatory T (Treg) cells may participate in mediating a suppressive microenvironment that blunts successful anti-tumor immunotherapy. Recent studies show that CD8⁺ Treg cells might impede effective immune responses to established tumors. However, there is limited research regarding CD8⁺ Treg cells in ovarian cancer (OC) patients. Here, we investigated CD8⁺ Treg cells in OC patients and their in vitro induction. The immunohistochemistry of tumor-infiltrating lymphocytes revealed a significant correlation between the intratumoral CD8⁺ T cells and the forkhead box p3 (Foxp3)⁺ cells in the intraepithelial and stromal areas of advanced OC tissues. We examined the expression of Treg markers in CD8⁺ T cells from the peripheral blood and fresh tumor tissues of OC patients using flow cytometry. Our results indicated an increase in the CD8⁺ Treg cell subsets of OC patients compared with those in patients with benign ovarian tumors and healthy controls, including an increased expression of CD25, cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), and Foxp3 and decreased CD28 expression. To demonstrate whether the tumor microenvironment could convert CD8⁺ effector T cells into suppressor cells, we used an in vitro transwell culturing system. Compared with the CD8⁺ T cells cultured alone, the CD8⁺ Treg cells induced in vitro by coculture with SK-OV-3/A2780 showed increased CTLA-4 and Foxp3 expression and decreased CD28 expression. In addition, the in vitro-induced CD8⁺ Treg cells inhibited naïve CD4⁺ T-cell proliferation, which was partially mediated through TGF-β1 and IFN-γ. Our study suggests that CD8⁺ Treg cells were increased in OC patients and could be induced in vitro, which may be the way that tumors limit antitumor immunity and evade immune surveillance.

Tumor-derived exosomes promote tumor progression and T-cell dysfunction through the regulation of enriched exosomal microRNAs in human nasopharyngeal carcinoma

Tumor-derived exosomes contain biologically active proteins and messenger and microRNAs (miRNAs). These particles serve as vehicles of intercellular communication and are emerging mediators of tumorigenesis and immune escape. Here, we isolated 30-100 nm exosomes from the serum of patients with nasopharyngeal carcinoma (NPC) or the supernatant of TW03 cells. Increased circulating exosome concentrations were correlated with advanced lymphoid node stage and poor prognosis in NPC patients (P < 0.05). TW03-derived exosomes impaired T-cell function by inhibiting T-cell proliferation and Th1 and Th17 differentiation and promoting Treg induction by NPC cells in vitro. These results are associated with decreases in ERK, STAT1, and STAT3 phosphorylation and increases in STAT5 phosphorylation in exosome-stimulated T-cells. TW03-derived exosomes increased the proinflammatory cytokines IL-1β, IL-6, and IL-10 but decreased IFNγ, IL-2, and IL-17 release from CD4⁺ or CD8+ T-cells. Furthermore, five commonly over-expressed miRNAs were identified in the exosomes from patient sera or NPC cells: hsa-miR-24-3p, hsa-miR-891a, hsa-miR-106a-5p, hsa-miR-20a-5p, and hsa-miR-1908. These over-expressed miRNA clusters down-regulated the MARK1 signaling pathway to alter cell proliferation and differentiation. Overall, these observations reveal the clinical relevance and prognostic value of tumor-derived exosomes and identify a unique intercellular mechanism mediated by tumor-derived exosomes to modulate T-cell function in NPC.

Lessons from rare tumors: Hepatic lymphoepithelioma-like carcinomas

In this review we focus on lymphoepithelioma-like hepatocellular carcinomas (LEL-HCC) and lymphoepithelioma-like cholangiocarcinomas (LEL-ICC). Despite their rarity, these tumors are of general interest because of their epidemiological and clinical features, and because they represent a distinct model of interaction between the immune system and neoplastic cells. Approximately half of LEL-HCC arise in the context of chronic hepatitis C virus (HCV) infection and have been described both in Eastern and Western patients. By contrast, LEL-ICC is associated in almost all cases with Epstein-Barr virus (EBV) infection and exhibits the same epidemiological features of EBV related malignancies. Compared with classical hepatocellular carcinoma and intrahepatic cholangiocarcinoma of corresponding stage, both LEL-HCC and LEL-ICC are characterized by lower rates of recurrence after surgery and better overall survival. How this behavior is related to distinct genetic alterations and tumor microenvironment is unclear. The pathophysiological mechanisms of lymphoid infiltrations seem to be different among the two groups of tumors. In fact, LEL-HCC frequently arises in the context of inflammatory changes driven by HCV infection, and has been recognized as a variant of classical hepatocellular carcinoma. At variance, lymphocyte recruitment of LEL-ICC is similar to that described in nasopharyngeal carcinoma and gastric LEL, and possibly depends on the expression pattern of latent EBV infection.

The immunology of Epstein-Barr virus-induced disease

Epstein-Barr virus (EBV) is usually acquired silently early in life and carried thereafter as an asymptomatic infection of the B lymphoid system. However, many circumstances disturb the delicate EBV-host balance and cause the virus to display its pathogenic potential. Thus, primary infection in adolescence can manifest as infectious mononucleosis (IM), as a fatal illness that magnifies the immunopathology of IM in boys with the X-linked lymphoproliferative disease trait, and as a chronic active disease leading to life-threatening hemophagocytosis in rare cases of T or natural killer (NK) cell infection. Patients with primary immunodeficiencies affecting the NK and/or T cell systems, as well as immunosuppressed transplant recipients, handle EBV infections poorly, and many are at increased risk of virus-driven B-lymphoproliferative disease. By contrast, a range of other EBV-positive malignancies of lymphoid or epithelial origin arise in individuals with seemingly intact immune systems through mechanisms that remain to be understood.

Constitutive induction of intestinal Tc17 cells in the absence of hematopoietic cell-specific MHC class II expression

The enteric pathogen Citrobacter rodentium induces a mucosal IL-17 response in CD4(+) T helper (Th17) cells that is dependent on the Nod-like receptors Nod1 and Nod2. Here, we sought to determine whether this early Th17 response required antigen presentation by major histocompatibility complex class II (MHCII) for full induction. At early phases of C. rodentium infection, we observed that the intestinal mucosal Th17 response was fully blunted in irradiated mice reconstituted with MHCII-deficient (MHCII(-/-) →WT) hematopoietic cells. Surprisingly, we also observed a substantial increase in the relative frequency of IL-17(+) CD8(+) CD4(-) TCR-β(+) cells (Tc17 cells) and FOXP3(+) CD8(+) CD4(-) TCR-β(+) cells in the lamina propria and intraepithelial lymphocyte compartment of MHCII(-/-) →WT mice compared with that in WT→WT counterparts. Moreover, MHCII(-/-) →WT mice displayed increased susceptibility, increased bacterial translocation to deeper organs, and more severe colonic histopathology after infection with C. rodentium. Finally, a similar phenotype was observed in mice deficient for CIITA, a transcriptional regulator of MHCII expression. Together, these results indicate that MHCII is required to mount early mucosal Th17 responses to an enteric pathogen, and that MHCII regulates the induction of atypical CD8(+) T-cell subsets, such as Tc17 cells and FOXP3(+) CD8(+) cells, in vivo.

Flow cytometry-based enumeration and functional characterization of CD8 T regulatory cells in patients with multiple myeloma before and after lenalidomide plus dexamethasone treatment

BACKGROUND

Multiple myeloma (MM) is a malignancy of plasma cells frequently associated with immune abnormalities. Several studies have confirmed that in MM immune deregulation can be mediated by increased numbers of CD4 T regulatory (Treg) cells, and these cells were also associated with poor outcome. In this study, we aimed to study CD8 Treg cells before and after lenalidomide plus dexamethasone (len-dex) treatment in MM patients.

METHODS

Using flow cytometry, we enumerated and assessed suppressive function of CD8 Treg cells in 16 MM patients before and after len-dex treatment.

RESULTS

Numbers of CD8 Treg cells (CD8+CD25hi+FoxP3+) (P < 0.01) were significantly increased in MM patients (before treatment) compared to healthy donors. However, no significant changes were observed in CD4 and CD8 T cells. A significant increase in CD8 Treg cells was observed after len-dex treatment compared to pre-treatment but no significant difference was observed in CD4 and CD8 T cells. Proliferation assay data showed that CD8 Treg cells inhibited proliferation of CD4 T cells and IFN-γ secretion in a concentration dependent manner. Suppressive activity of CD8 Treg cells did not differ significantly between healthy donors, untreated and len-dex treated MM patients. A significant abnormal level of IL-10 was observed from proliferation assays of untreated and len-dex treated MM patients compared to healthy donors (P ≤ 0.03).

CONCLUSIONS

Using flow cytometry, we have shown that suppressive CD8 Treg cells are increased in MM patients and len-dex treatment is unable to control these suppressive CD8 Treg cells.

Interferon regulatory factor 3 controls interleukin-17 expression in CD8 T lymphocytes

IFN regulatory factor (IRF) 3 plays a key role in innate responses against viruses. Herein we assessed its contribution to T-cell activation. We observed that poly(I:C)-induced IRF3 activation in CD8 T cells represses IL-17 expression in a type I IFN-independent fashion. Even in the absence of poly(I:C), polyclonally activated naïve IRF3(-/-) CD8 T cells expressed high levels of IL-17 and IL-23R in comparison with wild-type cells. Furthermore, IRF3(-/-) OT1 cells adoptively transferred into wild-type hosts also produced higher IL-17 levels upon immunization than their wild-type counterparts. This phenotype could be reversed by ectopic expression of IRF3, confirming that this effect is intrinsic to T cells. We show that IRF3 directly interacts with RORγt in the cytoplasm through its IRF interaction domain and limits its ability to bind and transactivate the IL-17 promoter. These observations uncover an unexpected role of IRF3 in the control of CD8 T-cell polarization.

CD30 is required for activation of a unique subset of interleukin-17A-producing γδ T cells in innate immunity against Mycobacterium bovis Bacillus Calmette-Guerin infection

Interleukin-17A (IL-17A)-producing γδ T cells are known to be activated following Mycobacterium bovis bacillus Calmette-Guérin (BCG) infection. Here, we show that CD30, a member of the tumor necrosis factor (TNF) receptor superfamily, is important for activation of IL-17A-producing γδ T cells after BCG infection. Vγ1(-) Vγ4(-) γδ T cells preferentially expressing Vγ6/Vδ1 genes were identified as the major source of IL-17A in the peritoneal cavity during the early stage of BCG infection. The number of IL-17A-producing Vγ1(-) Vγ4(-) γδ T cells bearing Vγ6 increased in peritoneal exudate cells (PEC) of wild-type (WT) mice but not in those of CD30 knockout (KO) mice in response to BCG infection. Consistently, CD30 ligand (CD30L) or CD30 expression, predominantly by Vγ1(-) Vγ4(-) γδ T cells, was rapidly upregulated after BCG infection. Inhibition of CD30L/CD30 signaling by in vivo administration of a soluble CD30 and immunoglobulin fusion protein (CD30-Ig) severely impaired activation of IL-17A-producing Vγ1(-) Vγ4(-) γδ T cells in WT mice, while stimulating CD30L/CD30 signaling by in vivo administration of agonistic anti-CD30 monoclonal antibody (MAb) restored IL-17A production by Vγ1(-) Vγ4(-) γδ T cells in CD30L KO mice after BCG infection. These results suggest that CD30 signaling plays an important role in the activation of IL-17A-producing Vγ1(-) Vγ4(-) γδ T cells bearing Vγ6 at an early stage of BCG infection.

Therapeutic targeting of regulatory T cells enhances tumor-specific CD8+ T cell responses in Epstein-Barr virus associated nasopharyngeal carcinoma

Epstein-Barr virus (EBV) is associated with multiple malignancies including nasopharyngeal carcinoma (NPC). In nasopharynx cancer, CD8+ T cells specific for EBV Nuclear Antigen-1 (EBNA-1) and Latent Membrane Protein 2 (LMP2) are important components of anti-tumor immunity since both are consistently expressed in NPC. We have previously shown that EBNA-1-specific CD8+ T cell responses were suppressed in NPC patients compared to healthy controls. We now find that CD8+ T cell responses specific for LMP2 are also abnormal in NPC patients, and both EBNA-1- and LMP2-specific responses are suppressed by regulatory T cells (Treg). EBNA-1 and LMP2-specific CD8+ T cell responses, as well as immune control of EBV-infected cells in vitro, could be restored by the depletion of Tregs and by use of a clinically approved drug targeting Tregs. Thus, in vivo modulation of Tregs may be an effective means of enhancing these anti-tumor immune responses in NPC patients.

Role of IL-17 in Glioma Progression

There is increasing evidence in the literature pointing to an important role of inflammation during initiation and progression of cancer. Glioblastoma is the most common malignant primary brain tumor with approximately 23,000 newly-diagnosed cases each year in the United States, and has a dismal median survival of only 15 months. Although the blood-brain barrier maintains an immune-privileged status of the brain under steady state, intracranial tumors including gliomas are invariably infiltrated with various types of immune cells. The T helper 17 (Th17) cells, a recently discovered interleukin (IL)-17-producing T cell subtype, have been reported in several extracranial and some intracranial tumors, where they have been implicated in either pro- or antitumor activity depending on the tumor type. Here, we present a succinct review of the current literature on the prevalence and potential role of IL-17 in malignant gliomas. Further mechanistic studies on IL-17 mediated inflammatory pathway in gliomas may provide with opportunities for novel immunotherapeutic interventions.

Functionally suppressive CD8 T regulatory cells are increased in patients with multiple myeloma: a cause for immune impairment

BACKGROUND

Multiple myeloma (MM) is a plasma cell malignancy frequently associated with impaired immune cell numbers and functions. In MM, several studies have previously shown that CD4 regulatory T (Treg) cells hamper effector T cell functions and enhance immune dysfunction. In this study, we aimed to prove the presence of functionally suppressive Treg cells expressing CD8 phenotype (CD8 Treg cells) in MM. To the best of our knowledge, this has not been reported previously in MM.

METHODS

We analyzed CD8 Treg cells and their transcription factor FoxP3 from 64 newly diagnosed MM patients using flow cytometry and real time-polymerase chain reaction (RT-PCR). RNA profile of cytokines in CD8 Treg cells was also assessed using RT-PCR. CD8 Treg cells from 5 MM patients and 5 healthy donors were functionally evaluated using proliferation assays.

RESULTS

CD8 Treg cells (CD8+CD25hi+) were significantly elevated in MM patients (P<0.0001), and their transcription factor FoxP3 expression was also higher in MM (P<0.0001) compared to healthy donors which was evidenced by flow cytometry and RT-PCR analyses. CD8 Treg cells negatively correlated with total lymphocyte count (P = 0.016). Functional studies revealed that CD8 Treg cells isolated from MM patients and healthy donors inhibited proliferation of CD4 T cells in a concentration dependent manner. In the presence of CD8 Treg cells in proliferation assays, level of IFN-γ was decreased but not IL-10. CD4 T cells from MM patients secreted abnormal level of IL-10 compared to healthy donors (P = 0.01) in proliferation assays without CD8 Treg cells. RNA profile of cytokines from CD8 Treg cells did not differ significantly between MM patients and healthy donors.

CONCLUSIONS

These findings show the presence of increased number of functionally suppressive CD8 Treg cells in MM patients. We believe that these suppressive CD8 Treg cells might enhance immune impairment and disease progression in MM.

Increased tumor-infiltrating CD8(+)Foxp3(+) T lymphocytes are associated with tumor progression in human gastric cancer

BACKGROUND

CD8(+)Foxp3(+) T lymphocytes have been detected in tumors. However, the distribution, phenotypic features, and regulation of these cells in gastric cancer remain unknown.

METHODS

The levels of CD8(+)Foxp3(+) T lymphocytes in the peripheral blood, tumor-draining lymph nodes, non-tumor tissues, and tumor tissues of patients with gastric cancer were detected by flow cytometry. Foxp3 induction in CD8(+)Foxp3(-) T cells was investigated in vitro. The suppressive function of CD8(+)Foxp3(+) T lymphocytes was analyzed by their effect on CD4(+) T-cell proliferation and IFN-γ production. The percentages of CD8(+)Foxp3(+) T lymphocytes were evaluated for the association with tumor stage.

RESULTS

The frequency of CD8(+)Foxp3(+) T lymphocytes in tumor tissues was significantly higher than that in non-tumor tissues, and similar results were also observed in tumor-draining lymph nodes compared with peripheral blood. Most intratumoral CD8(+)Foxp3(+) T lymphocytes were activated effector cells (CD45RA(-)CD27(-)). TGF-β1 levels were positively correlated with the frequency of CD8(+)Foxp3(+) T lymphocytes in tumor tissues, and in vitro TGF-β1 could induce the generation of CD8(+)Foxp3(+) T lymphocytes in a dose-dependent manner. Furthermore, intratumoral CD8(+)Foxp3(+) T lymphocytes suppressed the proliferation and IFN-γ production of CD4(+) T cells. Finally, intratumoral CD8(+)Foxp3(+) T lymphocytes were significantly increased with tumor progression in terms of tumor-node-metastasis (TNM) stage.

CONCLUSIONS

Our data have shown that increased intratumoral CD8(+)Foxp3(+) T lymphocytes are associated with tumor stage and potentially influence CD4(+) T-cell functions, which may provide insights for developing novel immunotherapy protocols against gastric cancer.

Differential cellular immune responses between chickens and ducks to H9N2 avian influenza virus infection

Avian influenza is an important infectious disease for the poultry industry and an ongoing public health concern. In this study, monoclonal antibodies (mAbs) specific to duck CD3ɛ, CD4 and CD8α were generated by immunizing mice with the corresponding Escherichia coli-expressed proteins and producing hybridomas. The resulting mAbs were used to investigate cellular immune responses of ducks and chickens during H9N2 avian influenza A virus (AIV) infection. By flow cytometric analysis, responses of T lymphocytes, especially CD8(+), CD8(+)CD25(+) and CD4(+)CD25(+) T cells, were stronger in ducks than in chickens following H9N2 AIV-infection. By quantitative real-time PCR analysis, virus mRNA could be detected in cloaca and oropharynx from both bird species and in spleens from chickens, and distinctive kinetics of transcriptional levels of interleukins and interferons were exhibited between chickens and ducks. With ducks showing more active and robust cellular immune responses than chickens, these results revealed that the distinct responses to H9N2 AIV infection may contribute to the different susceptibilities to AIV infection between the two species.

Increased production of nitric oxide correlates with tumor growth in Algerian patients with nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is thought to arise because of chronic inflammation. The correlation between nitric oxide (NO) production, a biomarker of inflammation and NPC development remains unexplored. To investigate this question, we performed a profile analysis on plasma collected from untreated, treated, remissive, cured and relapsing patients. Nitrites were measured to assess NO activity. We observed that increased nitrites concentrations in untreated and relapsing patients associated with tumor development. Moreover, nitrites levels were similar in remissive, cured and healthy individuals. Altogether, our results suggest that NO might be an interesting blood biomarker to monitor tumor growth in NPC patients.

Generation and immunologic functions of Th17 cells in malignant gliomas

Th17 cells, a recently discovered inflammatory T cell subtype, have been implicated with autoimmune disorders. However, mechanism of generation or functions of intratumoral Th17 cells are still unclear. We have been investigating the mechanism of induction and role of Th17 cells in malignant gliomas using primary tumor as well as cell lines. We report here that: (1) a higher frequency of Th17 cells in gliomas were associated with higher number of myeloid (CD11b) cells as well as the expression of TGF-β1 or IL-6; (2) conditioned medium from glioma cells (Gl CM) induced Th17 cell differentiation, which was inhibited by anti-TGF-β1 and anti-IL-6; (3) glioma-associated monocytes secreted Th17-promoting cytokines IL-1β and IL-23; (4) CM from glioma and monocyte co-culture (Gl+Mo CM) induced high frequency of Th17 cells in naïve T cell culture, which was abrogated by anti-IL-1β and anti-IL-23 antibodies; (5) In vitro Gl+Mo CM-mediated Th17 generation was associated with a decrease in IFN-γ and a concomitant increase in IL-10 secretion. Anti-TGF-β1, but not anti-IL-6, significantly reversed this cytokine profile. These results demonstrate prevalence of Th17 cells in gliomas and implicate the cytokines derived from the tumor as well as infiltrating myeloid cells in the induction of Th17 cells in glioma microenvironment. Moreover, the data also suggest that glioma-associated Th17 cells may contribute to immune-suppression via TGF-β1-induced IL-10 secretion. Further studies on the mechanism of tumor-infiltration, developmental pathways, and pro-/anti-tumor functions of Th17 cells will provide rationale for developing novel adjuvant immunotherapeutic strategies for malignant gliomas.

Dynamic education of macrophages in different areas of human tumors

Human tumor tissues can often be anatomically classified into areas of cancer nest, invading edge, and peritumoral stroma, each with distinct compositions and functional properties. Macrophages (Mφ) constitute a major component of the leukocyte infiltrate in tumors. These cells are derived from circulating monocytes, and in response to environmental signals, they exhibit distinct phenotypes with diverse functions. Soluble factors derived from cancer cells can alter the normal developmental process of Mφ that is intended to trigger transient early activation of monocytes in the peritumoral region, which in turn induces formation of suppressive Mφ in cancer nests. The activated monocytes in the peritumoral region attenuated the T-cell response by expressing B7-H1, and were superior to the suppressive tumor Mφ in inducing Th17 expansion, and thus repurpose the inflammatory response away from anti-tumor immunity (the sword) and towards tissue remodeling and proangiogenic pathways (a plowshare). In contrast, the suppressive Mφ can induce the production of Tregs in cancer nest. Accordingly, angiogenesis was most active at the invading edge, which was situated close to the peritumoral stroma with activated Mφ and the density of these activated monocytes is selectively associated with vascular invasion and metastasis in patients with hepatocellular carcinoma. These data reveal an intriguing mechanism in which human Th17 cells are generated and regulated by a fine-tuned collaborative action between different types of immune cells in distinct tumor microenvironments. These results give important new insights into the distinct role of macrophages in human tumor progression which would be helpful for the rational design of novel immune-based anticancer therapies.

Stromal CD4/CD25 positive T-cells are a strong and independent prognostic factor in non-small cell lung cancer patients, especially with adenocarcinomas

Within the concert of immune reactions against tumour cells cytotoxic and regulatory T-cells are of utmost importance. Several studies revealed contradictory results on this issue. We therefore focused on functional expression patterns and localization of tumour-infiltrating T-lymphocytes in non-small cell lung cancer (NSCLC) and their impact on patient's survival. 232 curatively operated NSCLC patients were included. After histological reevaluation and construction of tissue-multi-arrays immunohistochemical doublestains for CD3/CD8 and CD4/CD25 were performed to evaluate the total number of T-cells and their subsets of cytotoxic and activated T-cells. Additionally, the localization of the lymphocytes was included in the analysis. Hereby, T-cells within the tumour stroma were regarded as stromal, those among cancer cells as intraepithelial. The number of lymphocytes differed significantly between the histological subtypes being most prominent in large cell carcinomas. Survival analysis showed that high numbers of stromal T-lymphocytes are of beneficial prognostic influence in NSCLC patients. This also proved to be an independent prognostic factor in adenocarcinomas. Thus, in a large and well characterized cohort of NSCLC this is the first study to determine the prognostic value of stromal T-lymphocytes, as these are an independent prognosticator in NSCLC especially in adenocarcinomas whereas intraepithelial T-cells are not.

Host-tumor interactions in nasopharyngeal carcinomas

Like other human solid tumors, nasopharyngeal carcinoma (NPC) is a tissue and a systemic disease as much as a cell disease. Tumor cell population in NPC is highly heterogeneous. Heavy infiltration by non-malignant leucocytes results at least in part from the production of abundant inflammatory cytokines by the malignant epithelial cells. There is indirect evidence that interactions between stromal and malignant cells contribute to tumor development. Peripheral blood samples collected from NPC patients contain multiple products derived from the tumor, including cytokines, non-cytokine tumor proteins, tumor exosomes and viral nucleic acids. These products represent a potential source of biomarkers for assessment of tumor aggressiveness, indirect exploration of cellular interactions and monitoring of tumor response to therapeutic agents. Most NPC patients are immunocompetent with evidence of active humoral and cellular immune responses against EBV-antigens at the systemic level. Tumor development is facilitated by local immunosuppressive factors which are not fully understood. Local accumulation of regulatory T-cells is probably one important factor. At least two NPC tumor products are suspected to contribute to their expansion, the cytokine CCL20 and the tumor exosomes carrying galectin 9. In the future, new therapeutic modalities will probably aim at breaking immune tolerance or at blocking cellular interactions critical for tumor growth.