Expression of PD1 and BTLA on the CD8^+T Cell and γδT Cell Subsets in Peripheral Blood of Non-Small Cell Lung Cancer Patients

Objective To investigate the expression and regulation of programmed cell death protein 1(PD1),B lymphocyte and T lymphocyte attenuator(BTLA)in peripheral blood of patients with non-small cell lung cancer(NSCLC);to examine the correlation of the mRNA levels between PD and BTLA in NSCLC.Methods Flow cytometry was used to detect the expression of PD1 and BTLA on the surfaces of CD8^+T cells andγδ+T cells in the peripheral blood samples collected from 32 in-patients with stage IV NSCLC and 30 healthy individuals.We compared the expression of PD1 and BTLA on the surfaces ofγδ+T cells in the NSCLC patients with bone metastasis before and after the treatment of zoledronic acid.The correlations of PD1 and BTLA,as well as their ligands were analyzed using Pearson correlation analysis with the cBioPortal data platform.Results The frequency of PD1 on the surfaces of CD8^+T cells was significantly higher than that of theγδT cells in both healthy controls(t=2.324,P=0.024)and NSCLC patients(t=2.498,P=0.015).The frequency of PD1 on CD8^+T cells,rather than onγδ+T cells,was significantly upregulated in advanced NSCLC patients compared with that in healthy controls(t=4.829,P<0.001).The PD1+BTLA+γδT cells of the healthy controls were significantly lower than that of the NSCLC patients(t=2.422,P=0.0185).No differences in percentage of PD1+γδ+and BTLA+γδ+T cells were observed in 7 NSCLC patients with bone metastasis before and after zoledronic acid treatment.PD1 was positively correlated with BTLA in both lung adenocarcinoma(r=0.54;P<0.05)and lung squamous cell carcinoma(r=0.78;P<0.05).Conclusions The upregulation of co-inhibitory molecules occurs on the surfaces of both CD8^+T cells andγδT cells in advanced NSCLC,suggesting that these molecules were involved in regulating the inactivation of CD8^+T cells andγδ+T cells,immune escape and tumor invasion.

Glutamine deprivation impairs function of infiltrating CD8^(+)T cells in hepatocellular carcinoma by inducing mitochondrial damage and apoptosis

BACKGROUND The functions of infiltrating CD8^(+)T cells are often impaired due to tumor cells causing nutrient deprivation in the tumor microenvironment.Thus,the mechanisms of CD8^(+)T cell dysfunction have become a hot research topic,and there is increased interest on how changes in metabolomics correlate with CD8^(+)T cell dysfunction.AIM To investigate whether and how glutamine metabolism affects the function of infiltrating CD8^(+)T cells in hepatocellular carcinoma.METHODS Immunohistochemical staining and immunofluorescence were performed on surgically resected liver tissues from patients.Differentially expressed genes in infiltrating CD8^(+)T cells in hepatocellular carcinoma were detected using RNA sequencing.Activated CD8^(+)T cells were co-cultured with Huh-7 cells for 3 d.The function and mitochondrial status of CD8^(+)T cells were analyzed by flow cytometry,quantitative real-time polymerase chain reaction,and transmission electron microscopy.Next,CD8^(+)T cells were treated with the mitochondrial protective and damaging agents.Functional alterations in CD8^(+)T cells were detected by flow cytometry.Then,complete medium without glutamine was used to culture cells and their functional changes and mitochondrial status were detected.RESULTS There were a large number of infiltrating PD-1+CD8^(+)T cells in liver cancer tissues.Next,we cocultured CD8^(+)T cells and Huh-7 cells to explore the regulatory effect of hepatoma cells on CD8^(+)T cells.Flow cytometry results revealed increased PD-1 expression and decreased secretion of perforin(PRF1)and granzyme B(GZMB)by CD8^(+)T cells in the co-culture group.Meanwhile,JC-1 staining was decreased and the levels of reactive oxygen species and apoptosis were increased in CD8^(+)T cells of the co-culture group;additionally,the mitochondria of these cells were swollen.When CD8^(+)T cells were treated with the mitochondrial protective and damaging agents,their function was restored and inhibited,respectively,through the mitochondrial damage and apoptotic pathways.Subsequently,complete medium without glutamine was used to culture cells.As expected,CD8^(+)T cells showed functional downregulation,mitochondrial damage,and apoptosis.CONCLUSION Glutamine deprivation impairs the function of infiltrating CD8^(+)T cells in hepatocellular carcinoma through the mitochondrial damage and apoptotic pathways.

Peripheral CD4^(+)CD8^(+) double positive T cells:A potential marker to evaluate renal impairment susceptibility during systemic lupus erythematosus

Lupus nephritis(LN) has a high incidence in systemic lupus erythematosus(SLE) patients, but there is a lack of sensitive predictive markers. The purpose of the study was to investigate the association between the CD4^(+)CD8^(+)double positive T(DPT) lymphocytes and LN. The study included patients with SLE without renal impairment(SLE-NRI), LN, nephritic syndrome(NS), or nephritis. Peripheral blood lymphocyte subsets were analyzed by flow cytometry. Biochemical measurements were performed with peripheral blood in accordance with the recommendations proposed by the National Center for Clinical Laboratories. The proportions of DPT cells in the LN group were significantly higher than that in the SLE-NRI group(t=4.012, P<0.001), NS group(t=3.240,P=0.001), and nephritis group(t=2.57, P=0.011). In the LN group, the risk of renal impairment increased significantly in a DPT cells proportion-dependent manner. The risk of LN was 5.136 times(95% confidence interval, 2.115–12.473) higher in cases with a high proportion of DPT cells than those whose proportion of DPT cells within the normal range. These findings indicated that the proportion of DPT cells could be a potential marker to evaluate LN susceptibility, and the interference of NS and nephritis could be effectively excluded when assessing the risk of renal impairment during SLE with DPT cell proportion.

Effect of Mg^(2+)level on the functions of CD8^(+)T lymphocytes and NK cells in patients with COVID-19

Objective:To investigate the changes of Mg^(2+) levels in serum and peripheral blood mononuclear cells(PBMCs)of patients with COVID-19 and its effects on the functions of CD8^(+)T lymphocytes and NK cells.Methods:A total of 165 COVID-19 patients hospitalized in Ezhou Central Hospital from January 20 to February 20,2020 were divided into mild/common group(98 cases)and severe/critical group(67 cases).At the same time,34 healthy persons were selected as the control group.Peripheral blood was collected and PBMCs were isolated,the level of Mg^(2+) in serum and PBMCs was detected.The subsets of CD8^(+)T lymphocytes and NK cell and the expression levels of their surface inhibitory molecular PD-1 and activator molecular NKG2D were detected by flow cytometry.The correlation between Mg^(2+) concentration and the expression levels of PD-1 and NKG2D was also analyzed.Results:Compared with the control group,the concentration of Mg^(2+) in serum and PBMCs,the counts of CD8^(+)T lymphocytes and NK cell in patients with mild/common and severe/critical groups were significantly reduced(P<0.05),while the expression level of surface inhibitory molecular PD-1 were significantly increased(P<0.05),while the expression level of the activation molecule NKG2D were significantly decreased(P<0.05).However,the changes of the above indicators in patients with severe/critical group were greater than those in the mild/common group(P<0.05).In addition,the Mg^(2+) concentration in COVID-19 patients was negatively correlated with the expression level of PD-1 on CD8^(+)T lymphocytes and NK cells(P<0.05),and positively correlated with the expression levels of NKG2D(P<0.05).Conclusion:The concentration of Mg^(2+) in the serum and PBMCs of COVID-19 patients is significantly reduced,which may cause the function of CD8^(+)T lymphocytes and NK cells to be inhibited.

CD8^+调节性T细胞与器官移植

调节性T细胞（regulatory T cells，Treg）在维持机体免疫平衡方面发挥关键作用，对于器官移植术后诱导治疗和维持免疫耐受具有重要意义。

体外扩增小鼠CD8^+NK1.1^+NKT细胞的研究

目的研究体外扩增小鼠CD8+NK1.1+NKT细胞的表面分子标志、分化途径及细胞属性。方法获取超抗原SEB活化后体外扩增的小鼠效应细胞,用抗CD3-PerCP、CD4-FITC、CD8-PE、NK1.1-APC、TcRVβ8-FITC和CD69-FITC荧光抗体染色后,用流式细胞仪(FCMCalibueBD,USA)鉴定CD8+NK1.1+NKT细胞的表面分子标志和分化途径。用逆转录聚合酶链反应测定细胞内各种细胞因子和Foxp3基因转录水平。结果体外扩增的细胞中91.92%是CD8+T细胞,其中22.75%的细胞是CD8+NN1.1+NKT细胞,高于正常值(0.21±0.19,n=12)108倍以上。19.61%NKT细胞是TcRVβ8+NN1.1+NKT细胞。CD69分子的表达由原始0.11%增加到85.95%。CD4+T、CD3+T细胞亚群和CD4+NKT、CD3+NKT及CD4-CD8-NKT细胞亚群没有增加。扩增细胞TGF-β的mRNA表达呈阳性,不表达Foxp3和细胞因子IL-2、4、5、6、10及IFN-γ。CD8+NKT细胞直接由CD8+T细胞分化而来。结论 CD8+NK1.1+NKT细胞的分子特征为CD69+Foxp3-TcRVβ8+TGF-β+CD8+NK1.1+;它们既不是CD8+T调节细胞(Treg.),也不是CD4+NKT细胞,直接由CD8+T细胞分化而来,带有TCRVβ8受体,应属于T细胞亚群。

CD8^+T细胞依赖的急性移植物抗宿主病小鼠模型的建立

目的建立CD8^+T细胞依赖的急性移植物抗宿主病(GVHD)小鼠模型。方法分别以主要组织相容性抗原(MHC)相同,而次要组织相容性抗原(miHAs)不同的8～12周龄C3H．SW(H-2D^b,CD45．2^+)和B6/SJL(H-2D^b,CD45．1^+)雌性小鼠为供受体,从供体骨髓分离去除T细胞的骨髓细胞(T BM),与其脾脏和淋巴结来源的CD8^+T细胞混合,经尾静脉输注给受致死剂量^(137)γ照射的受体鼠。观察移植后受体的体重、毛色、皮肤和生存率的变化,并用流式细胞术(FACS)和组织病理学进一步分析受鼠靶器官细胞浸润和损伤状况。结果移植后受体鼠出现体重明显减轻、毛发脱落、皮肤溃疡等表现,并在28d后出现死亡；FACS证实浸润受鼠骨髓、脾脏和肝脏的细胞主要为CD45．2^+的供鼠细胞,实验组中还有大量CD45．2^+CD8^+T细胞浸润；组织病理学发现肝脏中大量淋巴细胞浸润,皮肤结构破坏,组织坏死。结论成功建立了miHAs不匹配的异基因骨髓移植诱导的CD8^+ T细胞依赖的GVHD动物模型,该模型模拟了目前临床病人采用的同种异基因骨髓移植配型方式,可为异基因骨髓移植GVHD发病机理及该病的防治研究提供良好的实验平台和工具。

X-ray irradiation selectively kills thymocytes of different stages and impairs the maturation of donor-derived CD4^+CD8^+ thymocytes in recipient thymus

The aim of the present study was to determine whether the sensitivity of thymocytes to X-ray radiation depends on their proliferative states and whether radiation impairs the maturation of donor-derived thymocytes in recipient thymus.We assigned 8-week-old C57BL/6J mice into three treatment groups：1） untreated;2） X-ray radiation;3） X-ray radiation plus bone marrow transplantation with donor bone marrow cells from transgenic mice express-ing enhanced green fluorescent protein（GFP） on a universal promoter.After 4 weeks,the size of the thymus,the number and proliferation of thymocytes and ratios of different stage thymocytes were analyzed by immunohisto-chemistry and flow cytometry.The results showed that：1） CD4＋CD8＋ thymocytes were more sensitive to X-ray radiation-induced cell death than other thymocytes;2） the proliferative capacity of CD4＋CD8＋ thymocytes was higher than that of other thymocytes;3） the size of the thymus,the number of thymocytes and ratios of thymo-cytes of different stages in irradiated mice recovered to the normal level of untreated mice by bone marrow trans-plantation;4） the ratio of GFP-positive CD4＋CD8＋ thymocytes increased significantly,whereas the ratio of GFP-positive CD4＋ or CD8＋ thymocytes decreased significantly.These results indicate that the degree of sensitivity of thymocytes to X-ray radiation depends on their proliferative states and radiation impairs the maturation of donor-derived CD4＋CD8＋ thymocytes in recipient thymus.

Myeloid cells meet CD8^(+)T cell exhaustion in cancer:What,why and how

Exhausted T cell(Tex)is a specific state of T cell dysfunction,in which these T cells gradually lose their effector function and change their phenotype during chronic antigen stimulation.The enrichment of exhausted CD8^(+)T cell(CD8^(+)Tex)in the tumor microenvironment is one of the important reasons leading to the poor efficacy of immunotherapy.Recent studies have reported many reasons leading to the CD8^(+)T cell exhaustion.In addition to cancer cells,myeloid cells can also contribute to T cell exhaustion via many ways.In this review,we discuss the history of the concept of exhaustion,CD8^(+)T cell dysfunction states,the heterogeneity,origin,and characteristics of CD8^(+)Tex.We then focus on the effects of myeloid cells on CD8^(+)Tex,including tumor-associated macrophages(TAMs),dendritic cells(DCs)and neutrophils.Finally,we systematically summarize current strategies and recent advancements in therapies reversing and CD8^(+)T cell exhaustion.

Revolutionizing tumor immunotherapy:unleashing the power of progenitor exhausted T cells

In exploring persistent infections and malignancies, a distinctive subgroup of CD8^(+) T cells, progenitor exhausted CD8^(+) T(Tpex) cells, has been identified. These Tpex cells are notable for their remarkable self-renewal and rapid proliferation abilities. Recent strides in immunotherapy have demonstrated that Tpex cells expand and differentiate into responsive exhausted CD8^(+) T cells, thus underscoring their critical role in the immunotherapeutic retort. Clinical examinations have further clarified a robust positive correlation between the proportional abundance of Tpex cells and enhanced clinical prognosis. Tpex cells have found noteworthy applications in the formulation of inventive immunotherapeutic approaches against tumors. This review describes the functions of Tpex cells in the tumor milieu, particularly their potential utility in tumor immunotherapy. Precisely directing Tpex cells may be essential to achieving successful outcomes in immunotherapy against tumors.

Notoginsenoside Ft1 inhibits colorectal cancer growth by increasing CD8^(+)T cell proportion in tumor-bearing mice through the USP9X signaling pathway

The management of colorectal cancer(CRC)poses a significant challenge,necessitating the development of innovative and effective therapeutics.Our research has shown that notoginsenoside Ft1(Ng-Ft1),a small molecule,markedly inhibits subcutaneous tumor formation in CRC and enhances the proportion of CD8^(+)T cells in tumor-bearing mice,thus restraining tumor growth.Investigation into the mechanism revealed that Ng-Ft1 selectively targets the deubiquitination enzyme USP9X,undermining its role in shieldingβ-catenin.This leads to a reduction in the expression of downstream effectors in the Wnt signaling pathway.These findings indicate that Ng-Ft1 could be a promising small-molecule treatment for CRC,working by blocking tumor progression via the Wnt signaling pathway and augmenting CD8^(+)T cell prevalence within the tumor environment.

A novel method for identifying SARS-CoV-2 infection mutants via an epitope-specific CD8^(+)T cell test

Since the outbreak of the coronavirus disease 2019(COVID-19)epidemic in 2019,the public health system has faced enormous challenges.Tracking the individuals who test positive for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is a key step for interrupting chains of transmission of SARS-CoV-2 and reducing COVID-19-associated mortality.With the increasing of asymptomatic infections,it is difficult to track asymptomatic infections through epidemiological surveys and virus whole-genome sequencing.However,due to the cross-reactivity of neutralizing antibodies produced by multiple virus subtypes,neutralizing antibody detection cannot be used to determine whether an individual has a history of infection with a specific subtype of SARS-CoV-2.We recruited 4 human leukocyte antigen A2(HLA-A2)infections,15 individuals who received three doses of inactivated vaccines,and 30 breakthrough infections after vaccination and discussed a case-tracking approach to detect epitope-specific CD8^(+)T cells in the peripheral blood of close contacts,including accurate HLA typing based on ribonucleic acid(RNA)-sequencing and flow cytometry data and the comparison and characterization of SARS-CoV-2 HLA-A2 and HLA-A24 epitope-specific CD8^(+)T cells.From individuals who received three doses of inactivated vaccine,we observed that the CD8^(+)T cell specificity for ancestral epitopes was significantly higher than for mutated epitopes,and the fold change of CD8^(+)T cells corresponding to mutated epitopes relative to ancestral epitopes was less than 1.The enzyme-linked immunospot(ELISpot)results further validate this result.This study forms a“method for understanding the infection history of SARS-CoV-2 subtypes based on the proportion of epitope-specific CD8^(+)T cells in the peripheral blood of subjects”,covering up to 46%of the population,including HLA-A2+and HLA-A24+donors,providing a novel method for SARS-CoV-2 infected case tracing.

Mettl3依赖的m^(6)A甲基化调控CD8^(+)T细胞效应分化和记忆形成

Efficient immune responses rely on the proper differentiation of CD8^(+)T cells into effector and memory cells.Here,we show a critical requirement of N^6-Methyladenosine(m^(6)A)methyltransferase Mettl3 during CD8^(+)T cell responses upon acute viral infection.Conditional deletion of Mettl3 in CD8^(+)T cells impairs effector expansion and terminal differentiation in an m^(6)A-dependent manner,subsequently affecting memory formation and the secondary response of CD8^(+)T cells.Our combined RNA-seq and m^(6)AmiCLIP-seq analyses reveal that Mettl3 deficiency broadly impacts the expression of cell cycle and transcriptional regulators.Remarkably,Mettl3 binds to the Tbx21 transcript and stabilizes it,promoting effector differentiation of CD8^(+)T cells.Moreover,ectopic expression of T-bet partially restores the defects in CD8^(+)T cell differentiation in the absence of Mettl3.Thus,our study highlights the role of Mettl3 in regulating multiple target genes in an m^(6)A-dependent manner and underscores the importance of m^(6)A modification during CD8^(+)T cell response.

Blockade of Tim-3 Pathway Ameliorates Interferon-γ Production from Hepatic CD8^+ T Cells in a Mouse Model of Hepatitis B Virus Infection

T cell immunoglobulin- and mucin-domain-containing molecule-3 （Tim-3） has been reported to participate in the pathogenesis of inflammatory diseases. However, whether Tim-3 is involved in hepatitis B virus （HBV） infection remains unknown. Here, we studied the expression and function of Tim-3 in a hydrodynamics-based mouse model of HBV infection. A significant increase of Tim-3 expression on hepatic T lymphocytes, especially on CD8^＋ T cells, was demonstrated in HBV model mice from day 7 to day 18. After Tim-3 knockdown by specific shRNAs, significantly increased IFN-γ production from hepatic CD8^＋ T cells in HBV model mice was observed. Very interestingly, we found Tim-3 expression on CD8^＋ T cells was higher in HBV model mice with higher serum anti-HBs production. Moreover, Tim-3 knockdown influenced anti-HBs production in vivo. Collectively, our data suggested that Tim-3 might act as a potent regulator of antiviral T-cell responses in HBV infection. Cellular ＆ Molecular Immunology.

Potentiating CD8^(+) T cell antitumor activity by inhibiting PCSK9 to promote LDLR-mediated TCR recycling and signaling

Metabolic regulation has been proven to play a critical role in T cell antitumor immunity.However,cholesterol metabolism as a key component of this regulation remains largely unexplored.Herein,we found that the low-density lipoprotein receptor(LDLR),which has been previously identified as a transporter for cholesterol,plays a pivotal role in regulating CD8+T cell antitumor activity.Besides the involvement of cholesterol uptake which is mediated by LDLR in T cell priming and clonal expansion,we also found a non-canonical function of LDLR in CD8+T cells:LDLR interacts with the T-cell receptor(TCR)complex and regulates TCR recycling and signaling,thus facilitating the effector function of cytotoxic T-lymphocytes(CTLs).Furthermore,we found that the tumor microenvironment(TME)downregulates CD8+T cell LDLR level and TCR signaling via tumor cell-derived proprotein convertase subtilisin/kexin type 9(PCSK9)which binds to LDLR and prevents the recycling of LDLR and TCR to the plasma membrane thus inhibits the effector function of CTLs.Moreover,genetic deletion or pharmacological inhibition of PCSK9 in tumor cells can enhance the antitumor activity of CD8+T cells by alleviating the suppressive effect on CD8+T cells and consequently inhibit tumor progression.While previously established as a hypercholesterolemia target,this study highlights PCSK9/LDLR as a potential target for cancer immunotherapy as well.

4-1BB signaling activates glucose and fatty acid metabolism to enhance CD8^(+) T cell proliferation

4-1BB(CD137)is a strong enhancer of the proliferation of CD8^(+)T cells.Since these cells require increased production of energy and biomass to support their proliferation,we hypothesized that 4-1BB signaling activated glucose and fatty acid metabolism.We found that treatment with agonistic anti-4-1BB mAb promoted the proliferation of CD8^(+)T cells in vitro,increasing their size and granularity.Studies with a glycolysis inhibitor and a fatty acid oxidation inhibitor revealed that CD8^(+)T cell proliferation required both glucose and fatty acid metabolism.Anti-4-1BB treatment increased glucose transporter 1 expression and activated the liver kinase B1(LKB1)-AMP-activated protein kinase(AMPK)-acetyl-CoA carboxylase(ACC)signaling pathway,which may be responsible for activating the metabolism of glucose and fatty acids.We also examined whether blocking glucose or fatty acid metabolism affected cell cycle progression and the anti-apoptotic effect of 4-1BB signaling.The increase of anti-apoptotic factors and cyclins in response to anti-4-1BB treatment was completely prevented by treating CD8^(+)T cells with the fatty acid oxidation inhibitor,etomoxir,but not with the glycolysis inhibitor,2-deoxy-D-glucose.We conclude that anti-4-1BB treatment activates glucose and fatty acid metabolism thus supporting the increased demand for energy and biomass,and that fatty acid metabolism plays a crucial role in enhancing the cell cycle progression of anti-CD3-activated CD8^(+)T cells in vitro and the anti-apoptotic effects of 4-1BB signaling on these cells.

Single cell atlas of developing mouse dental germs reveals populations of CD24^(+)and Plac8^(+)odontogenic cells

The spatiotemporal relationships in high-resolution during odontogenesis remain poorly understood.We report a cell lineage and atlas of developing mouse teeth.We performed a large-scale(92,688 cells)single cell RNA sequencing,tracing the cell trajectories during odontogenesis from embryonic days 10.5 to 16.5.Combined with an assay for transposase-accessible chromatin with high-throughput sequencing,our results suggest that mesenchymal cells show the specific transcriptome profiles to distinguish the tooth types.Subsequently,we identified key gene regulatory networks in teeth and bone formation and uncovered spatiotemporal patterns of odontogenic mesenchymal cells.CD24^(+)and Plac8^(+)cells from the mesenchyme at the bell stage were distributed in the upper half and preodontoblast layer of the dental papilla,respectively,which could individually induce nonodontogenic epithelia to form tooth-like structures.Specifically,the Plac8^(+)tissue we discovered is the smallest piece with the most homogenous cells that could induce tooth regeneration to date.Our work reveals previously unknown heterogeneity and spatiotemporal patterns of tooth germs that may lead to tooth regeneration for regenerative dentistry.

A novel cyclic peptide targeting LAG-3 for cancer immunotherapy by activating antigenspecific CD8^+ T cell responses

PD-1 and CTLA-4 antibodies offer great hope for cancer immunotherapy.However,many patients are incapable of responding to PD-1 and CTLA-4 blockade and show low response rates due to insufficient immune activation.The combination of checkpoint blockers has been proposed to increase the response rates.Besides,antibody drugs have disadvantages such as inclined to cause immune-related adverse events and infiltration problems.In this study,we developed a cyclic peptide C25 by using Ph.D.-C7C phage display technology targeting LAG-3.As a result,C25 showed a relative high affinity with human LAG-3 protein and could effectively interfere the binding between LAG-3 and HLA-DR(MHC-II).Additionally,C25 could significantly stimulate CD8^+T cell activation in human PBMCs.The results also demonstrated that C25 could inhibit tumor growth of CT26,B16 and B 16-OVA bearing mice,and the infiltration of CD8^+T cells was significantly increased while FOXP3^+Tregs significantly decreased in the tumor site.Furthermore,the secretion of IFN-γby CD8^+T cells in spleen,draining lymph nodes and especially in the tumors was promoted.Simultaneously,we exploited T cells depletion models to study the anti-tumor mechanisms for C25 peptide,and the results combined with MTT assay confirmed that C25 exerted anti-tumor effects via CD8+T cells but not direct killing.In conclusion,cyclic peptide C25 provides a rationale for targeting the immune checkpoint,by blockade of LAG-3/HLA-DR interaction in order to enhance anti-tumor immunity,and C25 may provide an alternative for cancer immunotherapy besides antibody drugs.

A naturally occurring CD8^＋CD122^＋ T-cell subset as a memory-like Treg family

Despite extensive studies on CD4^＋CD25^＋ regulatory T cells （Tregs） during the past decade, the progress on their clinical translation remains stagnant. Mounting evidence suggests that naturally occurring CD8^＋CD122^＋ T cells are also Tregs with the capacity to inhibit T-cell responses and suppress autoimmunity as well as alloimmunity. In fact, they are memory-like Tregs that resemble a central memory T cell （TcM） phenotype. The mechanisms underlying their suppression are still not well understood, although they may include IL-IO production. We have recently demonstrated that programmed death-1 （PD-1） expression distinguishes between regulatory and memory CD8^＋CD122^＋ T cells and that CD8^＋CD122^＋ Tregs undergo faster homeostatic proliferation and are more potent in the suppression of allograft rejection than conventional CD4^＋CD25^＋ Tregs. These findings may open a new line of investigation for accelerating effective Treg therapies in the clinic. In this review, we summarize the significant progress in this promising field of CD8^＋CD122^＋ Treg research and discuss their phenotypes, suppressive roles in autoimmunity and alloimmunity, functional requirements, mechanisms of action and potential applications in the clinic.

EBV-Induced Human CD8^＋ NKT Cells Synergise CD4^＋ NKT Cells Suppressing EBV-Associated Tumours upon Induction of Thl-Bias

CD8^＋ natural killer T （NKT） cells from EBV-associated tumour patients are quantitatively and functionally impaired. EBV-induced CD8^＋ NKT cells drive syngeneic T cells into a Thl-bias response to suppress EBV-associated malignancies. IL-4-biased CD4^＋ NKT cells do not affect either syngeneic T cell cytotoxicity or Th cytokine secretion. Circulating mDC1 cells from patients with EBV-associated malignancies impair the production of IFN-T by CD8^＋ NKT cells. In this study, we have established a human-thymus-SCID chimaera model to further investigate the underlying mechanism of EBV-induced CD8^＋ NKT cells in suppressing EBV-associated malignancies. In the human-thymus-SCID chimera, EBV-induced CD8^＋ NKT cells suppress EBV-associated malignancies in a manner dependent on the Thl-bias response and syngeneic CD3^＋ T cells. However, adoptive transfer with CD4^＋ NKT cells alone inhibits T cell immunity. Interestingly, CD4^＋ NKT cells themselves secrete high levels of IL-2, enhancing the persistence of adoptively transferred CD8^＋ NKT cells and T cells, thereby leading to a more pronounced T cell anti-tumour response in chimaeras co-transferred with CD4^＋ and CD8^＋ NKT cells. Thus, immune reconstitution with EBV-induced CD4^＋ and CD8^＋ NKT cells synergistically enhances T cell tumour immunity, providing a potential prophylactic and therapeutic treatment for EBV-associated malignancies.