CD4+ T cells support polyfunctionality of cytotoxic CD8+ T cells with memory potential in immunological control of tumor

Polyfunctionality/multifunctionality of effector T cells at the single cell level has been shown as an important parameter to predict the quality of T cell response and immunological control of infectious disease and malignancy. However, the fate of polyfunctional CD8⁺ CTLs and the factors that control the polyfunctionality of T cells remain largely unknown. Here we show that the acquisition of polyfunctionality on the initial stimulation is a sensitive immune correlate of CTL survival and memory formation. CD8⁺ T cells with high polyfunctionality, assessed with γ‐interferon and tumor necrosis factor‐α production and surface mobilization of the degranulation marker CD107a, showed enhanced Bcl‐2 expression, low apoptosis, and increased CD127^highKLRG1^low memory precursor phenotype. Consistent with these observations, CD8⁺ T cells were found to acquire high frequency of cells with polyfunctionality when stimulated in conditions known to enhance memory formation, such as the presence of CD4⁺ T cells, interleukin (IL)‐2, or IL‐21. Utilizing T‐cell receptor (TCR) transgenic mouse‐derived CD8⁺ T cells that express a TCR specific for a tumor‐derived neoantigen, we showed that polyfunctional tumor‐specific CTLs generated in the presence of CD4⁺ T cells showed long persistence in vivo and induced enhanced tumor regression when adoptively transferred into mice with progressing tumor. Acquisition of polyfunctionality thus impacts CTL survival and memory formation associated with immunological control of tumor.     

CD4+FoxP3+ regulatory T cells gradually accumulate in gliomas during tumor growth and efficiently suppress antiglioma immune responses in vivo

The suppressive activity of regulatory T cells (Treg) has been implicated as an important factor limiting immune mediated destruction of tumor cells. However, not much is known about the presence and function of Treg within tumors. Here we show in a syngeneic murine glioma model a time-dependent accumulation of CD4+FoxP3+ Treg in brain tumors. Further analysis revealed a time-dependent upregulation of CD25, CTLA-4, GITR and CXCR4 on intratumoral CD4+FoxP3+ Treg during tumor growth. Moreover, freshly isolated intratumoral Treg were highly suppressive when tested directly ex vivo. Treatment with anti-CD25 monoclonal antibodies (mAbs) significantly reduced the number of these highly suppressive CD4+FoxP3+ cells within the growing tumor and provoked a CD4 and CD8 T cell dependent destruction of the glioma cells. Combining Treg depletion with administration of blocking CTLA-4 mAbs further boosted glioma-specific CD4+ and CD8+ effector T cells as well as antiglioma IgG2a antibody titers resulting in complete tumor eradication without any signs of autoimmunity. These data illustrate that intratumoral accumulation and activation of CD4+FoxP3+ Treg act as a dominant immune escape mechanism for gliomas and underline the importance of controlling tumor-infiltrating Treg in glioma immunotherapy.     

Tumor PD-L1 engages myeloid PD-1 to suppress type I interferon to impair cytotoxic T lymphocyte recruitment

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MGBA负载脐带血DC诱导特异性CTL对乳腺癌细胞的杀伤作用

目的：观察乳腺珠蛋白（mammaglobin A, MGBA）负载脐带血来源树突状细胞（dendritic cell, DC）诱导产生的细胞毒性T细胞（cytotoxic T lymphocyte, CTL）对乳腺癌细胞的体外杀伤效果。方法：采集健康剖宫产女性志愿者的脐带血,分离脐带血单个核细胞并诱导DC生成,用MGBA致敏DC与自体淋巴细胞共培养诱导CTL。采用流式细胞术测定DC的表型(CD83、CD86、HLADR)变化,ELISA法测定IL-10、IL-12分泌水平,CCK-8法测定CTL对乳腺癌细胞的杀伤活性。结果：成功培养出形态典型、功能成熟的DC,MGBA负载DC诱导的MGBA特异性CTL对乳腺癌细胞MDA-MB-415 产生显著的杀伤效果（P<0.05）;加入HLA-I 抗体可显著减弱杀伤效果,加入HLA-II 抗体细胞毒活性无显著变化,加入HLA-I 抗体或HLA-II 抗体对正常乳腺细胞的杀伤性均无影响。结论：MGBA 能明显加强脐带血DC 诱导的CTL 对乳腺癌细胞的杀伤活性,该杀伤活性具有MHC限制性。     

FOLFOX4与1-D-甲基色氨酸联合治疗对荷胃癌小鼠调节性T细胞的影响

目的： 研究FOLFOX4与1-D-甲基色氨酸 (1-D-methyl tryptophan,1-D-MT)联合应用是否有利于改善荷胃癌小鼠的免疫耐受状态。方法：用脂质体转染法,将pcDNA3.1-IDO质粒和pcDNA3.1 (+)空质粒稳定转染MFC细胞,并设未转染组;用RT-PCR和Western blot法检测未转染组、空质粒转染组和pcDNA3.1-IDO转染组IDO mRNA和蛋白的表达;然后建立荷胃癌小鼠皮下移植瘤模型,并设未转染组、空质粒转染组,IDO+生理盐水 (NS)组、FOLFOX4组、1-D-MT组和FOLFOX4+1-D-MT联合处理组,采用流式细胞术检测各组小鼠脾脏中Treg细胞数量变化;RT-PCR检测FOXP3 mRNA表达量变化。结果：IDO mRNA与蛋白表达在稳定转染pcDNA3.1-IDO质粒组细胞较未转染组、空质粒转染组表达量明显增加 (P<0.05)。IDO+NS组小鼠脾脏Treg细胞比例及FOXP3 mRNA含量较未转染组、空质粒组均明显增多 (P<0.05)。FOLFOX4+1-D-MT组和1-D-MT组与FOLFOX4组相比,Treg细胞比例及FOXP3 mRNA含量均明显降低 (P<0.05),且联合治疗组较1-D-MT组降低更明显 (P<0.01)。结论：通过抑制Treg的增殖及降低FOXP3 mRNA表达,FOLFOX4与1-D-MT联合应用可降低机体免疫逃逸能力。     

Prognostic significance of regulatory T cells in tumor

Since entering the immunological stage several decades ago, regulatory T cell biology has been realized as fundamentally important in the prevention of autoimmune conditions, induction of transplant tolerance and the immune response to cancer. The role of regulatory T cells in tumor immunobiology is still being elucidated. Currently, regulatory T cells are implicated in the dampening of antitumor T‐cell responses both through direct and indirect means. A number of investigators have demonstrated that regulatory T cell density and location may serve as independent prognostic factors in several types of cancer and are alternately detrimental or beneficial to patient survival. In this article, we will review the characteristics and functional phenotype of classical regulatory T cells, describe their distribution and quantification in tumor‐bearing hosts and summarize recent studies investigating the prognostic significance of regulatory T cell number and locality in various cancers.     

Transcutaneous immunization in mice: induction of T-helper and cytotoxic T lymphocyte responses and protection against human papillomavirus-induced tumors

Previous reports have shown that transcutaneous immunization (TCI) with proteins or peptides in combination with adjuvants efficiently induces specific cellular and humoral immune responses. However, depending on the kind of skin pretreatment, induction of cellular immune responses was restricted to generation of either specific cytotoxic T lymphocytes (CTLs) or T-helper (Th) cells. In this study, we induced antigen-specific CTL responses together with the appropriate Th responses by TCI of C57BL/6 mice. We applied ovalbumin protein or an ovalbumin-derived fusion peptide containing a CTL and Th epitope together with a combination of cholera toxin (CT) and CpG oligodeoxynucleotide (CpG) onto cold wax-depilated and hydrated bare skin. TCI with the ovalbumin fusion peptide induced more robust CTL and Th responses than that with ovalbumin protein. The fusion peptide in combination with the nontoxic CT derivative CTA1-D2D1 and CpG induced an antigen-specific CTL response, albeit less efficiently than in combination with complete CT. Further, we compared the potency of HPV-16 E7 oncoprotein-derived peptides containing single (CTL) or multiple (CTL + Th + B cell) epitopes to induce effective CTL responses. Strong E7-specific CTL responses were detected only after TCI with the E7 multiepitope peptide. This peptide was also shown to protect mice against tumor growth after challenge with HPV-16 E7-positive tumor cells. TCI with E7 protein and CT/CpG led to formation of an E7-specific humoral immune response.     

肿瘤患者外周血调节性T细胞的检测及临床意义

目的：研究肿瘤患者外周血调节性T细胞水平的变化并探讨其临床意义,旨在了解肿瘤患者的免疫功能改变,为肿瘤患者临床治疗及判断预后提供依据。方法：采用流式细胞仪对40例肿瘤患者及40例正常人外周血CD4＋CD25＋T细胞、CD4＋CD25highT细胞及CD4＋CD25＋Foxp3＋Treg细胞水平进行检测。结果：肿瘤患者外周血中CD4＋CD25＋T细胞和CD4＋CD25highT细胞高于正常对照组（P〈0.05）;CD4＋CD25＋Foxp3＋调节性T细胞亦明显高于对照组（P〈0.01）。结论：肿瘤患者细胞免疫功能明显异常,CD4＋CD25＋Foxp3＋调节性T细胞增多可能是肿瘤患者免疫功能受抑的重要原因之一;调节性T细胞水平检测在评价肿瘤患者疗效及判断预后方面具有一定的临床价值。     

Apoptotic body-loaded dendritic cells efficiently cross-prime cytotoxic T lymphocytes specific for NA17-A antigen but not for Melan-A/MART-1 antigen

DCs hold promise for cancer immunotherapy due to their functional ambivalence: iDCs internalize antigens, then mDCs trigger naive T-cell activation. However, no consensus has been reached concerning the optimal mode of antigen acquisition for efficient cross-priming of TAA-specific CTLs, and this remains a field of investigation. Here, we used highly purified apobodies derived from an HLA-A*0201-negative melanoma line as a source of tumor antigens for HLA-A*0201 DCs. We compared in vitro mDCs loaded with apobodies to DCs loaded with antigenic peptides, NA17-A(1-9) and Melan-A/MART-1(26-35) A27L analogue, for their capacity to stimulate melanoma antigen-specific T cells from autologous PBLs. Apobody phagocytosis did not induce spontaneous DC maturation, but phagocytic DCs were still responsive to maturation signals, resulting in a functional ability to activate antigen-specific lymphocytes. NA17-A-specific T lymphocytes were activated by both types of stimulation, whereas only peptide-pulsed DCs stimulated the growth of Melan-A/MART-1-specific lymphocytes. We also observed a lack of staining of melanoma-derived apobodies with a Melan-A-specific MAb, suggesting protein alteration during apoptosis induction. After HLA-A*0201/NA17-A multimer sorting, antigen-specific lymphocytes induced by mature DCs loaded with either peptide or apobodies displayed similar functional capacity against peptide-pulsed T2 cells and melanoma cells. Therefore, apobody-loaded DCs can achieve T-cell priming similar to that induced by peptide-pulsed DCs, provided that the apoptotic process allows the preservation of antigen expression.     

Identification of an HLA-A*0201 cytotoxic T lymphocyte epitope specific to the endothelial antigen Tie-2

Tie-2 stabilises pericyte-endothelial interactions during angiogenesis and is highly expressed on endothelium during several diseases, including arthritis, age-related macular degeneration and cancer. A vaccine that targets endothelium overexpressing Tie-2 may result in vessel damage and stimulate an inflammatory cascade resulting in disease regression. We have identified a region unique to Tie-2 (amino acids 1-196) that is homologous in humans and mice. Using computer algorithms, several HLA-A*0201 epitopes that are identical in mice and humans were predicted within this region; however, binding assays showed that the majority of these epitopes were of low affinity. Modification of the anchor residues of 4 epitopes enhanced HLA binding. These epitopes were incorporated by site-directed mutagenesis into a Tie-2 DNA construct. Immunisation of HLA*0201 transgenic mice with one of the modified Tie-2 constructs stimulated CTLs that recognised both wild-type and modified peptide-pulsed target cells. In contrast, no CTLs were generated in mice immunised with wild-type Tie-2 construct, demonstrating that the modified epitope was necessary in the generation of CTLs. Moreover, CTLs from mice immunised with the modified construct killed HLA-A*0201 endothelial cells overexpressing Tie-2. Our study demonstrates that it is possible to break tolerance to the endothelial antigen Tie-2, suggesting that it may be feasible to design a vaccine to activate CTLs to kill endothelial cells overexpressing Tie-2.     

A reduction of recipient regulatory T cells by cyclophosphamide contributes to an anti-tumor effect of nonmyeloablative allogeneic stem cell transplantation in mice

We have recently established a unique model system of nonmyeloablative allogeneic stem cell transplantation (SCT) for treatment of murine solid tumors, based on cyclophosphamide‐induced tolerance. An injection of allogeneic donor spleen cells and bone marrow cells (BMC) followed by cyclophosphamide treatment induced a stable mixed chimerism with long lasting tolerance to the allografts. A donor lymphocyte infusion (DLI) in the cyclophosphamide‐induced tolerant mice exerted strong anti‐tumor effects on an MBT‐2 murine bladder tumor, MBT‐2 via their graft versus tumor (GVT) activity. In the present study, we determined whether a cyclophosphamide‐induced reduction of naturally occurring regulatory T cells (Tregs) was associated with the anti‐tumor activity in our nonmyeloablative SCT system. The number of recipient CD4+ CD25+ Foxp3+ Tregs significantly decreased 3 days after an intraperitoneal injection of cyclophosphamide in C3H/HeN mice that had been injected with spleen cells and BMC of donor AKR/J mice, compared with the number of CD4+ CD25+ Foxp3‐ T cells. An adoptive transfer of CD4+ CD25+ T cells from naïve C3H/He x AKR/J F1 mice into recipient mice 1 day after DLI significantly suppressed the expansion and IFN‐γ production of host‐reactive donor CD4+T cells and hampered the MBT‐2 anti‐tumor activity when compared with the transfer of CD4+ CD25‐ T cells. These results indicated that cyclophosphamide‐induced reduction of recipient Tregs is associated with retardation of tumor progression via the expansion of host‐reactive donor T cells and IFN‐γ production after DLI in our nonmyeloablative SCT system.     

Donor lymphocyte infusion leads to diversity of specific T cell responses and reduces regulatory T cell frequency in clinical responders

T cell responses against malignant cells play a major role in maintaining remission and prolonging overall survival in patients after allogeneic stem cell transplantation and donor lymphocyte infusion (DLI) due to graft-versus-leukemia effect. For better characterization of the T cell responses, we assessed frequency and diversity of leukemia-associated antigen (LAA)-specific cytotoxic T cells using ELISpot and pMHC multimer assays and analyzed the frequency of regulatory T cells (Treg) as well as cytokine profiles before/after DLI. The data were correlated to the clinical course of patients. Significantly more LAA-derived T cell epitopes (p = 0.02) were recognized in clinical responders (R) when compared to nonresponders (NR). In addition, pMHC multimer-based flow cytometry showed a significantly higher frequency of LAA-specific T cells in R versus NR. The frequency of Treg in R decreased significantly (p = 0.008) while keeping stable in NR. No differences in T cell subset analysis before/after DLI were revealed. Clinical responders were correlated to specific immune responses and all clinical responders showed an increase of specific immune responses after DLI. Cytokine assays using enzyme-linked immunosorbent assay showed a significant increase of IL-4 after DLI. Taken together, an increase of specific CTL responses against several LAA after DLI was detected. Moreover, this study suggests that enhanced LAA diversity in T cell responses as well as decreasing numbers of Treg contribute to clinical outcome of patients treated with DLI.     

Tumor‐specific cytotoxic T cell generation and dendritic cell function are differentially regulated by interleukin 27 during development of anti‐tumor immunity

Interleukin (IL‐) 27 is a member of IL‐12 cytokine family with Th1‐promoting and anti‐inflammatory effects. IL‐27 has been shown to facilitate tumor‐specific cytotoxic T lymphocyte (CTL) induction against various tumors. However, IL‐27 suppresses cytokine production of lymphocytes and antigen‐presenting function of dendritic cells (DCs). To examine the in vivo role of IL‐27 in generation of anti‐tumor immunity, we examined IL‐27‐mediated antitumor‐effects using WSX‐1 (IL‐27 receptor α chain)‐deficient (WSX‐1^?/?) mice. In WSX‐1^?/? mice inoculated with B16 melanoma cells, tumor growth was higher than in wild‐type (WT) mice. Accordingly, tumor‐specific CTL generation was lower in WSX‐1^?/? mice than in WT mice. CTL induction in WSX‐1^?/? mice was not restored by transfer of WT DCs pulsed with TRP2 peptide, indicating that IL‐27 is directly required for generation of tumor‐specific CTLs. However, when transferred into tumor‐bearing mice, WSX‐1^?/? DCs pulsed with TRP2 peptide was more potent than WT DCs in tumor growth inhibition and generation of CTLs, indicating suppressive effects of IL‐27 on DC function. Finally, the combination of WT CD8⁺ T cells and KO DCs is more potent in generation of antigen‐specific CTLs than any other combinations. Expression of perforin gene and percentages of tumor‐specific CD8⁺ T cells were also the highest in the combination of WT CD8+ T cells and WSX‐1^?/? DCs. It was thus revealed that IL‐27 promotes CTL generation while suppressing DC function during generation of tumor immunity. The combination of WT T cells and IL‐27 signal‐defective DCs may have therapeutic potential against tumors. © 2008 Wiley‐Liss, Inc.     

Elimination of regulatory T cells is essential for an effective vaccination with tumor lysate-pulsed dendritic cells in a murine glioma model

Both melanoma and glioma cells are of neuroectodermal origin and share common tumor associated antigens. In this article, we report that the melanocyte differentiation antigen TRP2 (tyrosinase-related protein 2) is not predominantly involved in the tumor rejection of a syngeneic murine glioma. Although GL261 glioma cells endogenously expressed TRP2 and were lysed by TRP2 specific cytotoxic T cells (CTLs) in vitro, vaccinations with TRP2 peptide-pulsed dendritic cells (DCs) could only induce minor antiglioma responses in a prophylactic setting and failed to work in a stringent setting where vaccine and tumor were administered on the same day. Further analysis revealed that TRP2 is not recognized by bulk CTLs after depletion of regulatory T cells which results in tumor rejections in vivo. In contrast to TRP2 peptide-pulsed DC, tumor lysate-pulsed DCs were more potent as a vaccine and completely protected mice from tumor outgrowth in a prophylactic setting. However, the vaccine efficacy of tumor lysate-pulsed DC was not sufficient to prevent the tumor outgrowth when tumors were inoculated the same day. In this case, Treg depletion before vaccination was essential to boost antiglioma immune responses leading to the rejection of 80% of the mice and long-term immunity. Therefore, we conclude that counteracting the immunosuppressive glioma tumor environment via depletion of regulatory T cells is a prerequisite for successful eradication of gliomas after targeting multiple tumor antigens by using tumor lysate-pulsed DCs as a vaccine in a more stringent setting.     

微波消融治疗对肝癌小鼠调节性 T 细胞的影响

目的：研究微波消融治疗荷肿瘤后小鼠的Treg和淋巴细胞亚群的变化,探讨微波消融治疗荷瘤小鼠后的机体免疫功能的变化.方法：建立H22荷瘤小鼠模型,分为荷瘤对照组和微波消融组.微波消融荷瘤小鼠肿瘤.流式细胞术检测脾脏中的CD4＋CD25＋T细胞、CD25＋FOXP3＋T细胞、CD4＋T细胞、CD8＋T细胞.结果：与荷瘤对照组相比,微波消融治疗后21天、28天组小鼠CD25＋FOXP3＋T细胞明显下降,差异有统计学意义（P＜0.05）,以术后28天下降更为明显（P＜0.01）.微波消融术后各组小鼠CD4＋/CD8＋比值明显增高（P＜0.05）.结论：微波消融治疗减低Tregs比例可能是热消融治疗提高机体抗肿瘤免疫作用的主要机制.微波消融治疗肿瘤后,Treg数量下降及功能降低,且CD4＋/CD8＋比值升高,提示了微波消融治疗肝癌可以改善机体的免疫状态.     

Soluble γc receptor attenuates anti‐tumor responses of CD8+ T cells in T cell immunotherapy

Previous studies have shown that soluble common γ‐chain (sγc) modulates CD4⁺ T cell immunity with antagonistic functions in γc cytokine signaling. However, the role of sγc in functional properties of effector CD8⁺ T cells has not been fully defined. In this study, we report a new mechanism by which the anti‐tumor activity of mouse CD8⁺ T cells is suppressed in sγc of their own producing. While sγc significantly inhibits cytotoxicity of CD8⁺ T cells, blocking sγc production by genetic modification leads to potentiated effector function of CD8⁺ T cells, establishing persistent CD8⁺ T cells. This is due to the modulation of IL‐2 and IL‐15 signaling, which is required for expansion and survival of CD8⁺ T cells as well as for optimal cytotoxic activity. More efficient management of tumor growth was achieved by an adoptive transfer of sγc‐deficient CD8⁺ T cells than that of wild‐type or sγc‐overexpressing CD8⁺ T cells. Blocking of IL‐2 and IL‐15 signaling by sγc attenuates the capacity of CD8⁺ T cells to mount an optimal response to the tumor, with both quantitative and qualitative effects on antigen‐specific CD8⁺ T cells. These results could have a critical implication for the generation and survival of optimal effector T cells for adoptive immunotherapy of cancer.     

Improved survival of chimeric antigen receptor‐engineered T (CAR‐T) and tumor‐specific T cells caused by anti‐programmed cell death protein 1 single‐chain variable fragment‐producing CAR‐T cells

Chimeric antigen receptor‐engineered T (CAR‐T)‐cell therapy holds significant promise for the treatment of hematological malignancies, especially for B‐cell leukemia and lymphoma. However, its efficacy against non‐hematological malignancies has been limited as a result of several biological problems characteristic of the tumor microenvironment of solid tumors. One of the main hurdles is the heterogeneous nature of tumor‐associated antigens (TAA) expressed in solid tumors. Another hurdle is the inefficient activation and limited persistence of CAR‐T cells, mainly as a result of T‐cell exhaustion caused by immunosuppressive factors in the tumor microenvironment. In the present study, to address these problems, we engineered CAR‐T cells to produce antagonistic anti‐programmed cell death protein 1 (PD‐1) single‐chain variable fragment (scFv), by which PD‐1‐dependent inhibitory signals in CAR‐T cells and adjacent tumor‐specific non‐CAR‐T cells are attenuated. In mouse solid tumor models, PD‐1 scFv‐producing CAR‐T cells induced potent therapeutic effects superior to those of conventional CAR‐T cells, along with a significant reduction of apoptotic cell death not only in CAR‐T cells themselves but also in TAA‐specific T cells in the tumor tissue. In addition, the treatment with anti‐PD‐1 scFv‐producing CAR‐T cells resulted in an increased concentration of PD‐1 scFv in tumor tissue but not in sera, suggesting an induction of less severe systemic immune‐related adverse events. Hence, the present study developed anti‐PD‐1 scFv‐producing CAR‐T cell technology and explored its cellular mechanisms underlying potent antitumor efficacy.     

肝癌荷瘤小鼠调节性T细胞数量的改变及其与肿瘤生长的关系

目的研究肝癌荷瘤小鼠调节性T细胞数量的改变及其与肿瘤生长的关系。方法采用小鼠肝癌细胞系H22接种BALB／c小鼠,建立肝癌模型;采用流式细胞术方法检测CD4^＋ CD25^＋T／CD4^＋T细胞的比例;以RT-PCR和流式细胞术检测Foxp3基因的表达。以免疫磁珠分选法纯化CD4^＋CD25^＋T和CD4^＋CD25^-T细胞;在体外,用3H-TdR掺入法检测T细胞的增殖情况;在体内,观察荷瘤小鼠来源的CD4^＋CD25^＋T细胞对肿瘤生长的作用。结果（1）荷瘤小鼠在引流淋巴结中,CD4^＋CD25^＋T细胞占CD4＋T细胞（18．80％±0．06％）比例增高,与对照组（9．50％±0．03％）相比,差异有统计学意义（P〈0．01）;在非引流淋巴结（LN）和脾脏（SP）中,荷瘤小鼠CD4^＋CD25^＋T／CD4^＋T比例分别为16．28％±0．02％和17．28％±0．06％,与对照组9．50％±0．03％和11．08％±0．04％相比,差异有统计学意义（P〈0．01,P〈0．05）;同时,调节性T细胞特异性标志Foxp3 mRNA的表达也升高。在同一只荷瘤小鼠中,引流淋巴结中CD4^＋CD25^＋T细胞数量（18．8％±0．06％）较对侧非引流淋巴结（16．28％±0．02％）略有升高,但差异无统计学意义（P〉0．05）。（2）从荷瘤小鼠中纯化的CD4^＋CD25^＋T细胞,在体外对抗CD3单抗的刺激无反应,但能抑制CD4^＋CD25^-T细胞的增殖。（3）CD4^＋CD25^＋T／CD4＋T比例与肿瘤大小呈正相关,并且可以抑制CD4^＋CD25^-T细胞的抗肿瘤效应。结论肝癌细胞在小鼠体内的生长可以提高调节性T细胞的数量,其数量的高低与肿瘤的大小呈正相关,提示清除调节性T细胞将是肿瘤免疫治疗的策略之一。     

Inflammatory and regulatory T cells contribute to a unique immune microenvironment in tumor tissue of colorectal cancer patients

Colorectal cancer is one of the five leading causes of cancer mortality worldwide. The mechanisms of pathogen clearance, inflammation and regulation by T cells in the healthy bowel are also important in controlling tumor growth. The majority of studies analyzing T cells and their relationship to colorectal tumor growth have focused on individual T cell markers or gene clusters and thus the complexity of the T cell response contributing to the growth of the tumor is not clear. We have studied the T cells in colorectal cancer patients and have defined a unique T cell signature for colorectal tumor tissue. Using a novel analytical flow cytometric approach in concert with confocal microscopy, we have shown that the tumor has a lower frequency of effector T cells (CD69+), but a higher frequency of both regulatory (CD25hi Foxp3+) and inflammatory T cells (IL‐17+) compared with associated nontransformed bowel tissue. We have also identified minor populations of T cells expressing conventional markers of both inflammatory and regulatory T cells (CD4+IL‐17+Foxp3+) in the tumor tissue. These cells may represent intermediate populations or they may dictate an inflammatory versus regulatory function in surrounding T cells. Together, these data describe an immune microenvironment in colorectal cancer unique to the tumor tissue and distinct from the surrounding healthy bowel tissue, and this distinct environment is reflected by a gradient of T cells expressing markers of multiple T cell populations. These findings may be used to improve diagnosis and prognosis of colorectal cancer patients.     

Human T‐cell lymphotropic/leukemia virus type 1 (HTLV‐1) Tax‐specific T‐cell exhaustion in HTLV‐1‐infected individuals

Adult T‐cell leukemia/lymphoma (ATL) is caused by Human T‐cell lymphotropic/leukemia virus type 1 (HTLV‐1), and a higher HTLV‐1 provirus load in PBMC is a risk factor for ATL development. Here, we document a significant inverse correlation between the function of HTLV‐1 Tax‐specific CTL (Tax‐CTL), as assessed by ex vivo cytokine production in response to cognate peptide, and the HTLV‐1 provirus load in PBMC in both HTLV‐1 asymptomatic carriers (AC) (Spearman rank correlation coefficient [Rs] = ?0.494, P = .037, n = 18) and ATL patients (Rs = ?0.774, P = .001, n = 15). There was also a significant correlation between the HTLV‐1 provirus load and the percentage of PD‐1‐positive Tax‐CTL in both HTLV‐1 AC (Rs = 0.574, P = .013) and ATL patients (Rs = 0.676, P = .006). Furthermore, the percentage of PD‐1‐positive Tax‐CTL was inversely correlated with their function in HTLV‐1 AC (Rs = ?0.542, P = .020), and ATL patients (Rs = ?0.639, P = .010). These findings indicate that the function of Tax‐CTL decreased as their programmed cell death protein 1 (PD‐1) levels increased, parallel to the increased HTLV‐1 provirus load in PBMC. We propose that functional Tax‐CTL are crucial for determining the HTLV‐1 provirus load in PBMC, not only in HTLV‐1 AC, but also in ATL, and that PD‐1 expression levels are reliable markers of Tax‐CTL function. Thus, modulating the immunological equilibrium between Tax‐CTL and HTLV‐1‐infected cells to achieve dominance of functional effectors could represent an ideal strategy for controlling HTLV‐1‐associated disease.