Human germinal centres engage memory and naive B cells after influenza vaccination

正Influenza viruses remain a major public health threat.Seasonal influenza vaccination in humans primarily stimulates pre-existing memory B cells, leading to a transient wave of circulating antibody-secreting plasmablasts1-3.This recall response contributes to original antigenic sin, the selective boosting of antibody specificities from prior exposures to influenza virus antigens4.It remains unclear whether such vaccination can also induce germinal centre(GC) reactions in the draining lymph     

Whole tumor antigen vaccination using dendritic cells: Comparison of RNA electroporation and pulsing with UV-irradiated tumor cells

Because of the lack of full characterization of tumor associated antigens for solid tumors, whole antigen use is a convenient approach to tumor vaccination. Tumor RNA and apoptotic tumor cells have been used as a source of whole tumor antigen to prepare dendritic cell (DC) based tumor vaccines, but their efficacy has not been directly compared. Here we compare directly RNA electroporation and pulsing of DCs with whole tumor cells killed by ultraviolet (UV) B radiation using a convenient tumor model expressing human papilloma virus (HPV) E6 and E7 oncogenes. Although both approaches led to DCs presenting tumor antigen, electroporation with tumor cell total RNA induced a significantly higher frequency of tumor-reactive IFN-gamma secreting T cells, and E7-specific CD8+ lymphocytes compared to pulsing with UV-irradiated tumor cells. DCs electroporated with tumor cell RNA induced a larger tumor infiltration by T cells and produced a significantly stronger delay in tumor growth compared to DCs pulsed with UV-irradiated tumor cells. We conclude that electroporation with whole tumor cell RNA and pulsing with UV-irradiated tumor cells are both effective in eliciting antitumor immune response, but RNA electroporation results in more potent tumor vaccination under the examined experimental conditions.     

CD4(+) CD25(+) T cells prevent arthritis associated with Borrelia vaccination and infection

CD4(+) CD25(+) T cells are a population of regulatory T cells associated with control of arthritis in anti-interleukin-17 antibody-treated Borrelia-vaccinated and challenged gamma interferon-deficient mice. Here, we present direct evidence that adoptive transfer of enriched CD4(+) CD25(+) T cells from these mice can prevent the development of arthritis in Borrelia-vaccinated and challenged mice. These findings establish a major role for CD4(+) CD25(+) T cells in the prevention of arthritis in Borrelia-vaccinated and challenged animals.     

Antibody-targeted vaccination to lung dendritic cells generates tissue-resident memory CD8 T cells that are highly protective against influenza virus infection

Influenza virus gains entry into the body by inhalation and initiates its replication cycle within the lung. The early stage of infection, while the virus is confined to the lung mucosa, provides the ideal window of opportunity for an effective immune response to control the infection. Tissue-resident memory (Trm) CD8 T cells, located in a variety of tissues including the lung, are ideally situated to act during this window and stall the infection. The factors involved in the differentiation of lung Trm cells remain poorly defined. We demonstrate that recognition of antigen presented locally by dendritic cells (DCs) and transforming growth factor-β (TGFβ) signaling are both required. We exploited this knowledge to develop an antibody-targeted vaccination approach to generate lung Trm cells. Delivering antigen exclusively to respiratory DCs results in the development of lung CD8 Trm cells that are highly protective against lethal influenza challenge. Our results describe an effective vaccination strategy that protects against influenza virus infection.     

应用抗CD137L单克隆抗体阻断CD137/CD137L信号通路抑制小鼠SGVHD的发生

目的：探讨抗CD137L单克隆抗体阻断CD137/CD137L信号通路在小鼠同基因型移植物抗宿主病（SGVHD）诱导中的作用,以阐明SGVHD的发生机制.方法：用致死剂量的X射线照射受体小鼠后,移植同基因骨髓细胞,从移植的当天开始连续21天腹腔注射环孢素A（CsA）诱导SGVHD.于诱导的第10天起给治疗组小鼠腹腔注射抗CD137L单克隆抗体进行干预治疗.观察各组小鼠的临床症状（体重下降,腹泻）、组织病理学和细胞因子改变.结果：抗CD137L单克隆抗体治疗组小鼠SGVHD的发生率明显低于诱导组小鼠SGVHD的发生率（25% vs 67%）,两者差异具有统计学意义（P＜0.01）.SGVHD小鼠肝脏和结肠组织病理学呈严重炎症细胞浸润,组织中细胞因子IL-12、IFN-γ、TNF-α mRNA水平升高.而抗体治疗组小鼠织病理学呈轻度炎症细胞浸润,组织中细胞因子IL-12、IFN-γ、TNF-α mRNA水平较低或检测不到.结论：单独用抗CD137L单克隆抗体阻断CD137/CD137L信号通路可明显抑制小鼠SGVHD的发生,提示CD137/CD137L信号通路在小鼠SGVHD免疫反应中是较为重要的通路之一.     

CD4 T cells in tumor immunity

T cell immunity is the key to protective immune responses against tumors. Traditionally, this function has been ascribed to CD8 T lymphocytes with cytotoxic activity, which are restricted by MHC class I molecules. In recent years the realization that CD4 T cells can also play a relevant role in protective anti-tumor responses has received growing attention. Here we will discuss the role of MHC class II-restricted T cells in response to, and in the regulation of, tumor antigens. Emphasis will be placed on four areas: (1) the role of CD4 T cell immunity in tumor protection in animal models and putative mode of action, (2) tumor antigens recognized by human CD4 T cells, (3) the cooperation between two CD4 T cells of different specificity as a new way to jump start the response against sub-immunogenic determinants of tumor antigens in a tolerant environment, and (4) the negative impact of regulatory CD4 T cells on anti-tumor T cell responses. By drawing attention to these four areas, it is our intention to provide the reader with a comprehensive view of issues of contemporary importance for this field, in the expectation that the information will help a better design of therapeutic cancer vaccines.     

CD4 T cells in tumor immunity

T cell immunity is the key to protective immune responses against tumors. Traditionally, this function has been ascribed to CD8 T lymphocytes with cytotoxic activity, which are restricted by MHC class I molecules. In recent years the realization that CD4 T cells can also play a relevant role in protective anti-tumor responses has received growing attention. Here we will discuss the role of MHC class II-restricted T cells in response to, and in the regulation of, tumor antigens. Emphasis will be placed on four areas: (1) the role of CD4 T cell immunity in tumor protection in animal models and putative mode of action, (2) tumor antigens recognized by human CD4 T cells, (3) the cooperation between two CD4 T cells of different specificity as a new way to jump start the response against sub-immunogenic determinants of tumor antigens in a tolerant environment, and (4) the negative impact of regulatory CD4 T cells on anti-tumor T cell responses. By drawing attention to these four areas, it is our intention to provide the reader with a comprehensive view of issues of contemporary importance for this field, in the expectation that the information will help a better design of therapeutic cancer vaccines.     

CD137-induced apoptosis is independent of CD95

CD95 (APO-1/Fas) and CD137 (ILA/4-1BB) are members of the tumour necrosis factor receptor family, and both are involved in induction of apoptosis in lymphocytes. Contrary to the case of CD95, apoptosis by CD137 is caused by cross-linking of the respective ligand rather than the receptor. Nothing is known so far about the mechanism of CD137-induced cell death. Here, we show that immobilized CD137 protein induces expression of CD95 in resting primary T and B lymphocytes. However, induction of apoptosis by CD137 is independent of CD95, because: (1) antagonistic anti-CD95 antibody fragments do not block CD137-induced apoptosis; and (2) CD137, but not anti-CD95, can induce apoptosis in resting lymphocytes.     

Human CD4 and CD8 regulatory T cells in infectious diseases and vaccination

Regulatory T cells (Tregs) are crucial players in balancing inflammation and antigen specific immune responses. In chronic infectious diseases, Tregs dampen inflammation to limit tissue damage, but they can also inhibit ensuing effector immunity, thereby impairing pathogen clearance. Chronic persistent infections by human pathogens such as parasites, viruses, and (myco)bacteria can all result in the induction of both CD4(+) and CD8(+) Tregs. However, among the many different subsets of Tregs that are induced, mostly CD4(+) Tregs have been studied. A remarkably increased frequency has been observed at the site of infection, supporting a role in pathogen containment. Indeed, antigen specificity has been demonstrated for several pathogen derived antigens. Here we review different classes of human Tregs in infectious diseases, including CD4 and CD8 Treg subsets. A better understanding of the induction and activity of Tregs is relevant for the design of better vaccines that optimally induce effector immunity without co-induction of excessive Treg activity.     

CD133+ colon cancer cells are more interactive with the tumor microenvironment than CD133- cells

Experimental data indicate that colorectal cancer cells with CD133 expression exhibit enhanced tumorigenicity over CD133-negative (CD133-) cells. We hypothesized that CD133-positive (CD133+) cells, compared with CD133-, are more tumorigenic because they are more interactive with and responsive to their stromal microenvironment. Freshly dissected and dissociated cells from a primary colon cancer were separated into carcinoma-associated fibroblasts (CAF) and the epithelial cells; the latter were further separated into CD133+ and CD133- cells using fluorescence-activated cell sorter. The CD133+ cells formed large tumors in non-obese diabetic-severe combined immunodeficient (NOD-SCID) mice, demonstrating the phenotypic cellular diversity of the original tumor, whereas CD133- cells were unable to sustain significant growth. Affymetrix gene array analyses using t-test, fold-change and multiple test correction identified candidate genes that were differentially expressed between the CD133+ vs CD133- cells. RT-PCR verified differences in expression for 30 of the 46 genes selected. Genes upregulated (+ vs - cells) included CD133 (9.3-fold) and CXCR4 (4-fold), integrin β8 and fibroblast growth factor receptor 2. The CAF highly express the respective ligands: stromal-derived factor-1 (SDF-1), vitronectin and FGF family members, suggesting a reciprocal relationship between the CD133+ and CAF cells. SDF-1 caused an increase in intracellular calcium in cells expressing both CD133 and CXCR4, confirming functional CXCR4. The CD133+/CXCR4+ phenotype is increased to 32% when the cells are grown in suspension compared with only 9% when the cells were allowed to attach. In Matrigel 3-D culture, the CD133+/CXCR4+ group treated with SDF-1 grew more colonies compared with vehicle, as well as significantly larger colony sizes of tumor spheres. These data demonstrate proof of principle that the enhanced tumorigenic potential of CD133+, compared with CD133-, cells is due to their increased ability to interact with their neighboring CAF.     

Induction of proliferation and monocytic differentiation of human CD34+ cells by CD137 ligand signaling

CD137 is a member of the tumor necrosis factor receptor family and is involved in the regulation of activation, proliferation, differentiation, and cell death of leukocytes. Bidirectional signaling exists for the CD137 receptor/ligand system, as CD137 ligand, which is expressed as a transmembrane protein, can also transduce signals into the cells on which it is expressed. In this study, we have identified expression of CD137 in human bone marrow and expression of CD137 ligand on a subset of CD34+ cells. Cross-linking of CD137 ligand on CD34+ cells by CD137 ligand agonists induces activation, prolongation of survival, proliferation, and colony formation. CD137 ligand agonists induce differentiation of early hematopoietic progenitor cells to colony-forming units-granulocyte/macrophage and subsequently to monocytes and macrophages but not to dendritic cells. These data uncover a novel function of CD137 and CD137 ligand by showing their participation in the growth and differentiation of hematopoietic progenitor cells.     

Circulating CD137+CD8+ T cells accumulate along with increased functional regulatory T cells and thoracic tumour burden in lung cancer patients

CD137 is a promising target for immunostimulation strategies against cancer. Previous studies showed that CD137⁺CD8⁺ T cells are enriched in antitumour effector T cells in both preclinical tumour models and cancer patients, but to date, such T cells in the blood of lung cancer patients have not been sufficiently investigated. In this study, circulating antigen‐activated CD8⁺ T cell subsets, identified as CD137⁺CD8⁺ or PD‐1⁺ (programmed cell death protein 1) CD8⁺, and regulatory T cells (Treg), identified as CD4⁺CD25⁺CD127^low/?, in 40 untreated lung cancer patients and in 49 age‐ and sex‐matched healthy controls (HCs) were assessed by flow cytometry. Results were evaluated for associations with lung cancer patient clinical characteristics. Correlations between antigen‐activated CD8⁺ T cells and effector Treg (CTLA‐4⁺ [cytotoxic T‐lymphocyte antigen 4] CD4⁺CD25⁺CD127^low/?) were also investigated. Higher percentages of PD‐1⁺, CD137⁺ and PD‐1⁺CD137⁺ amongst CD8⁺ T cells were observed in lung cancer patients compared with HCs. The percentages of CD137⁺CD8⁺ and PD‐1⁺CD137⁺CD8⁺ T cell subsets amongst CD8⁺ T cells were positively correlated with thoracic tumour burden and were strongly positively correlated with the percentage of effector Treg subset. Smoking patients harboured higher percentages of the PD‐1⁺CD8⁺ T cell subset compared with non‐smoking patients. This study demonstrated that circulating antigen‐activated CD8⁺ T cells accumulated in lung cancer patients along with increased effector Treg and thoracic tumour burden. These findings aid a better understanding of immune‐host interactions in lung cancer patients using peripheral blood, and further support immunotherapeutic intervention strategies using combination therapy for differential control of Treg and activation of tumour‐specific effector T cells.     

Murine CD8 lymphocyte expansion in vitro by artificial antigen-presenting cells expressing CD137L (4-1BBL) is superior to CD28, and CD137L expressed on neuroblastoma expands CD8 tumour-reactive effector cells in vivo

The ability to expand tumour-infiltrating lymphocytes in vitro has been greatly enhanced by the use of antigen-independent mechanisms of immune cell costimulation. We have produced human, using the K562 cell line, and murine, using YAC-1 cells, artificial antigen presenting cells (aAPC) and demonstrate that these cell types stimulate murine lymphocyte populations in distinct ways. Using aAPC that have been transfected with CD137L (4-1BBL) and CD32 (FcRgammaII), as a means to bind anti-CD3 and anti-CD28 antibody, we found that CD4 cells preferentially expanded in vitro with K562 aAPC, while CD8 cells expanded with both K562 and YAC-1 aAPC. Co-stimulation mediated by CD137L on aAPC was superior to that mediated by anti-CD28 antibody. This was seen in both long and short-term expansion assays, and by the rapid induction of a CD8+ DX5+ population. DX5 serves, under these in vitro conditions, as a general marker for lymphocyte activation. In vivo, the superiority of CD137L was demonstrated by the induction of T helper 1 effectors seen in freshly isolated splenocytes from mice immunized with CD137L-expressing neuroblastoma tumour vaccines. The ability to stimulate a strong CD8 CTL response in vivo correlated with the induction of a DX5+ cell population in splenocytes with a memory-effector phenotype. The presence of this unique DX5+ cell population, phenotypically distinct with regards to CD69 and CD62L expression from DX5+ cells induced by aAPC in vitro, may be associated with the ability of CD137L to induce strong anti-tumour immunity.     

抗原基因修饰的树突状细胞诱导机体产生特异性免疫应答的实验研究

目的：探讨腺病毒介导的肿瘤抗原基因修饰的树突状细胞（ＤＣ） 体内免疫后对抗原特异性抗肿瘤免疫反应的诱导作用。方法：以βｇａｌ 为模拟抗原,以转染有ＬａｃＺ基因并稳定表达βｇａｌ 的淋巴瘤细胞Ｅ２２ 为肿瘤细胞模型,用携带编码βｇａｌ的ＬａｃＺ基因的重组腺病毒载体（ＡｄＬａｃＺ） 转染小鼠骨髓ＤＣ,检测转染的效率及ＬａｃＺ基因修饰ＤＣ刺激Ｔ细胞增殖的能力,观察皮下免疫ＬａｃＺ基因修饰ＤＣ后小鼠引流区淋巴结细胞数量和组分的变化以及诱导产生ＣＴＬ和抵抗Ｅ２２ 细胞再攻击的能力。结果：ＬａｃＺ基因修饰后２４ 、４８ 、７２ ｈ,均能检测到８０％ 以上的ＤＣ表达βｇａｌ,此基因修饰的ＤＣ可有效刺激同基因型小鼠脾脏Ｔ淋巴细胞增殖反应;将其皮下免疫小鼠１ ｗ 后再接种Ｅ２２ 细胞,小鼠的存活期较其他ＤＣ免疫小鼠显著延长,但对Ｂ１６ 黑色素瘤细胞的攻击无免疫保护作用。此外,ＬａｃＺ基因修饰的ＤＣ免疫小鼠的引流淋巴结细胞数量显著增加,且产生了针对Ｅ２２ 的而非ＥＬ４ 或Ｂ１６ 的特异性ＣＴＬ。结论：腺病毒介导的肿瘤抗原基因修饰的ＤＣ能有效诱导机体产生特异的抗肿瘤免疫反应。     

Harnessing CD1d-restricted iNKT cells to design novel vaccination strategies

The success of vaccination strategies depends on the efficient generation of appropriate antigen-specific T- and B-cell responses. The unique position of invariant natural killer T (iNKT) cells at the interface of the innate and adaptive immune systems and their ability to direct the maturation of dendritic cells and B cells offer the possibility of harnessing them to ‘jump-start’ the antigen-specific immune response to both microbial pathogen and tumour antigens. In this brief review, the biology and activation of iNKT cells is discussed, with particular emphasis on the development of pharmacological agents to be used as adjuvants to antigenic proteins, to achieve an iNKT cell-dependent augmentation of antigen-specific T- and B-cell responses. In addition, we discuss the future directions and challenges in translating these findings from experimental data obtained in mice to use in the clinic.     

Apoptotic tumor cells induce IL-27 release from human DCs to activate Treg cells that express CD69 and attenuate cytotoxicity

Intrinsic immunosuppression is a major obstacle for successful cancer therapy. The mechanisms for the induction and regulation of immunosuppression in humans are ill defined. A microenvironmental component that might prevent antitumor immunity is the presence of dying tumor cells, which are abundant following conventional cancer ablation methods such as chemo- or radiotherapy. Shedding of apoptotic debris and/or secretion of factors to the tumor bed or draining lymph nodes thus might have a profound impact on professional phagocytes, such as DCs, and subsequent priming of lymphocytes. Here, we exposed human DCs to supernatants of live, apoptotic, or necrotic human breast cancer cells and cocultured them with autologous T cells. Priming with apoptotic debris prevented DCs from establishing cytotoxicity toward live human tumor cells by inducing a Treg-cell population, defined by coexpression of CD39 and CD69. Immunosuppression via Treg cells was transferable and required the release of sphingosine-1-phosphate (S1P) from apoptotic cells, acting via S1P receptor 4 on DCs to induce IL-27 secretion. We propose that CD69 expression on CD39(+) Treg cells enables them to interact with CD73-expressing CD8(+) T cells to generate adenosine, thereby suppressing cytotoxicity. These findings aid the understanding of how dying tumor cells limit antitumor immunity.