Administration of interleukin-12 enhances the therapeutic efficacy of dendritic cell-based tumor vaccines in mouse hepatocellular carcinoma

Dendritic cells (DCs) are potent antigen-presenting cells that are capable of priming systemic antitumor immune response. Here, we evaluated the combined effectiveness of tumor lysate-pulsed DC immunization and interleukin (IL)-12 administration on the induction of antitumor immunity in a mouse hepatocellular carcinoma (HCC) model. Mouse DCs were pulsed with lysate of BNL 1ME A.7R.1 (BNL), a BALB/c-derived HCC cell line, and then injected into syngeneic mice in combination with systemic administration of IL-12. Lymphocytes from mice treated with BNL lysate-pulsed DCs and IL-12 showed stronger cytolytic activity and produced higher amounts of IFN-gamma than those from mice treated with BNL lysate-pulsed DCs alone. Although immunization with BNL lysate-pulsed DCs alone did not lead to complete regression of established tumors, it significantly inhibited tumor growth compared with vehicle injection. Importantly, the combined therapy of BNL lysate-pulsed DCs and IL-12 resulted in tumor rejection or significant inhibition of tumor growth compared with mice treated with BNL lysate-pulsed DCs alone. In vivo lymphocyte depletion experiments demonstrated that this combination was dependent on both CD8+ and CD4+ T cells, but not natural killer cells. These results demonstrated that IL-12 administration enhanced the therapeutic effect of immunization of tumor lysate-pulsed DCs against HCC in mice. This combination of IL-12 and DCs may be useful for suppressing the growth of residual tumor after primary therapy of human HCC.     

Melanoma‐targeted chemo‐thermo‐immuno (CTI)‐therapy using N‐propionyl‐4‐S‐cysteaminylphenol‐magnetite nanoparticles elicits CTL response via heat shock protein‐peptide complex release

Melanogenesis substrate, N‐propionyl‐4‐S‐cysteaminylphenol (NPrCAP) is specifically taken up by melanoma cells and inhibits their growth by producing cytotxic free radicals. By taking advantage of this unique chemical agent, we have established melanoma‐targeting intracellular hyperthermia by conjugating NPrCAP with magnetite nanoparticles (NPrCAP/M) upon exposure to an alternating magnetic field (AMF). This treatment causes cytotoxic reaction as well as heat shock responses, leading to elicitation of antitumor immune response, which was proved by tumor rechallenge test and CTL induction. We found the level of heat shock protein 72 (Hsp72) to be increased in the cell lysate and culture supernatant after intracellular hyperthermia. Melanoma‐specific CD8⁺ T‐cell response to dendritic cells loaded with hyperthermia‐treated tumor lysate was enhanced when compared with non‐treated tumor lysate. When heat shock protein, particularly Hsp72, was immuno‐depleted from hyperthermia‐treated tumor cell lysate, specific CD8⁺ T‐cell response was abolished. Thus, it is suggested that antitumor immune response induced by hyperthermia using NPrCAP/M is derived from the release of HSP‐peptide complex from degraded tumor cells. Therefore, this chemo‐thermo‐immuno (CTI)‐therapy might be effective not only for primary melanoma but also for distant metastasis because of induction of systemic antimelanoma immune responses. (Cancer Sci 2010)     

rhHSP70联合冻融抗原修饰树突状细胞诱导的抗乳腺癌作用

  目的   利用rhHSP70联合树突状细胞递呈肿瘤抗原的特性提高细胞毒T淋巴细胞（CTLs）对乳腺癌细胞的杀伤活性。   方法   外周血单个核细胞体外经GM-CSF和IL-4诱导产生树突状细胞,负载冻融抗原肽的同时加入新型热休克蛋白（rhHSP70）,不同分组分别诱导自体CTLs产生。ELISA测定CTLs杀伤活性和细胞因子的分泌。   结果   冻融抗原肽致敏的DCs促进CTLs增殖,上调CTLs中CD3+和CD8+T细胞群及Th1型细胞因子的分泌;体外实验中具有对人乳腺癌细胞MCF-7的杀伤活性,在加入rhHSP70后效果更加明显,并能显著增强CTLs对肿瘤细胞的杀伤率。   结论   hHSP70联合肝癌冻融抗原修饰DCs,能够促进DCs的成熟,增强DCs刺激淋巴细胞增殖的能力,诱导的CTLs在体外对乳腺癌细胞能产生高效杀伤力。rhHSP70增强DCs抗肿瘤能力的机制可能与其促进DCs成熟有关。       

抑制SOCS1联合OK-432刺激的DC疫苗抗肿瘤效应的初步研究

BACKGROUND & OBJECTIVE: Suppressor of cytokine signaling 1 (SOCS1) plays a critical role in antitumor immunity. Down-regulating SOCS1 in antigen-presenting dendritic cells (DCs) could enhance antigen-specific antitumor immunity. This study was to investigate the antigen-specific antitumor effect and mechanism of DCs with siRNA-mediated inhibition of SOCS1, stimulated by OK-432 and pulsed with hepatocellular carcinoma cell line HepG2 antigens. METHODS: The expression of SOCS1 in immature DCs was down-regulated by RNA interference (RNAi). DCs were pulsed with lysate of HepG2 cells and stimulated with OK-432. The morphology of DCs was observed under converted phase microscopy. Phenotypic changes in cells after stimulation were characterized by flow cytometry (FCM). The Alamar Blue assay was adopted to evaluate the activation and proliferation of autologous lymphocytes induced by mature DCs. The cytotoxicity of cytotoxic T lymphocytes (CTLs) elicited by modified DCs to HepG2, EC109 and K562 cells was tested by the lactate dehydrogenase (LDH) assay. RESULTS: Cells displaying a typical morphology and phenotypic properties of mature DCs were obtained successfully. The expression of SOCS1 in DCs was down-regulated by SOCS1 RNAi. Mature DCs showed high expressions of CD80, CD83, CD86, and HLA-DR. Pulsing of DCs with lysate of HepG2 had no influence on the phenotypic properties of DCs. Down-regulating SOCS1 expression enhanced the maturation of DCs. The modified DC tumor vaccine stimulated the proliferation of autologous lymphocytes effectively, and the proliferation rate of T cells was (110.7+/-22.2)%. After being activated by modified DCs, TCLs exerted a specific and effective killing effect on HepG2 cells, but not on EC109 and K562 cells. CONCLUSION: Mature DCs could induce antigen-specific antitumor immunity against hepatocellular carcinoma after silencing of SOCS1 by siRNA, stimulation by OK-432 and pulsing of DCs with HepG2 cell antigens.     

Immune responses of dendritic cells combined with tumor-derived autophagosome vaccine on hepatocellular carcinoma

Background

To induce and collect tumor-derived autophagosomes (DRibbles) from tumor cells as an antitumor vaccine by inhibiting the functions of proteasomes and lysosomes.

Methods

Dendritic cells (DCs) generated from peripheral blood mononuclear cell (PBMC) of hepatocellular carcinoma (HCC) patients were cocultured with DRibbles, and then surface molecules of DCs, as well as surface molecules on DCs, were determined by flow cytometry. Meanwhile, immune responses of the DCs-DRibbles were examined by mixed lymphocyte reactions.

Results

DRibbles significantly induced the expression of CD80, CD83, CD86 and HLA-DR on DCs. The enzyme-linked immunosorbnent assay (ELISA) showed that IFN-γ levels after vaccination increased than before in most patients, but CD8+ proportion of PBMC increased only in nine patients. Higher levels of IFN-γ were detected in the CD8+ cells than CD4+ T cells. These results suggested that DCs-DRibbles vaccine could induce antigen-specific cellular immune response on HCC and could prime strong CD8+ T cell responses, supporting it as a tumor vaccine candidate.

Conclusions

Our results demonstrate that HCC/DRibbles-pulsed DCs immunotherapy might be deployed as an effective antitumor vaccine for HCC immunotherapy in clinical trials.     

Tumor cell lysate-pulsed human dendritic cells induce a T-cell response against pancreatic carcinoma cells: an in vitro model for the assessment of tumor vaccines

Dendritic cells (DCs) are potent antigen-presenting cells and play a pivotal role in T cell-mediated immunity. DCs have been shown to induce strong antitumor immune responses in vitro and in vivo, and their efficacy is being investigated in clinical trials. Compared with vaccination strategies directed against a single tumor antigen, tumor-cell lysate as the source of antigen offers the potential advantage of inducing a broad T-cell response against multiple known, as well as unknown, tumor-associated antigens expressed by the individual tumor. We used pancreatic carcinoma cell lines to develop an in vitro model for monitoring T-cell responses induced by lysate-pulsed DCs. Monocyte-derived DCs of HLA-A2(+) donors were pulsed with lysate generated from the HLA-A2(+) pancreatic carcinoma cell line Panc-1. In some experiments, the immunogenic protein keyhole limpet hemocyanin (KLH) was added to the lysate. Subsequently, the antigen-loaded DCs were activated with tumor necrosis factor-alpha and prostaglandin E(2). Autologous mononuclear cells were cocultured with DCs in the presence of low-dose interleukin (IL)-2 and IL-7 and were restimulated weekly with new DCs. High levels of IL-12 and IFN-gamma could be detected in the supernatants, indicating a T-helper type 1-type immune response. This cytokine profile was associated with the expression of the activation marker CD69 on both T helper and CTLs and with an antigen-induced proliferative T-cell response. After 4 weeks, CTL-mediated cytotoxicity was assessed. Tumor cell lysis was specific for Panc-1 tumor cells and was MHC class I-restricted. Cytokine secretion, CD69 expression of T cells, and antigen-induced T-cell proliferation correlated with the cytotoxic activity and were more pronounced when KLH was added to the lysate. This is the first study to show that T cells specific for pancreatic carcinoma cells can be generated in vitro by lysate-pulsed DCs and that the T-cell response can be enhanced by KLH. This in vitro model can be applied to compare different strategies in the development of DC-based tumor vaccines.     

Generation of in vitro B-CLL specific HLA class I restricted CTL responses using autologous dendritic cells pulsed with necrotic tumor lysate

New approaches in the treatment of chronic B lymphocytic leukemia (B-CLL) have led to improved clinical response rates. In this setting there is a need to evaluate novel therapeutic approaches that aim to eradicate minimal residual B-CLL cells following an initial favorable response. The use of tumor lysate-pulsed dendritic cells (DC) represents a potentially important development in the field of cancer vaccination. B-CLL is ideally suited for DC-based vaccination since tumor cells are readily available (peripheral blood) and both known (tumor idiotype) and unknown antigens can be exploited to stimulate immune responses. In the current study we have evaluated the ability to stimulate in vitro autologous immune reactivity against target B-CLL cells using autologous DCs pulsed with B-CLL tumor lysate. Enhanced specific T cell IFN-gamma expression was detected in 9 of 14 patients evaluated. These responses were specific with increased levels of IFN-gamma mRNA measurable in T-cells stimulated with NC-DCs and not unpulsed DCs or DCs pulsed with normal B cell lysate. CTLs demonstrating increased levels of IFN-gamma mRNA also lysed autologous B-CLL targets cells in an MHC class 1-restricted manner by (51)chromium release assay. Priming target leukemic cells with CD40 ligand and IL-4 enhanced CTL killing. The effector CTL displayed negligible toxicity against NK susceptible target cells K-562 and spared CD19(+)CD5(-) normal B cells in cytotoxicity assays. The specificity of the CTL response was confirmed by blocking HLA class I molecules and cold target inhibition assays.     

Dendritic cells pulsed with alpha-fetoprotein and mutant P53 fused gene induce bi-targeted cytotoxic T lymphocyte response against hepatic carcinoma

Dendritic cell (DC)-based immunotherapy is rapidly emerging as a promising treatment in cancer therapy. We had previously shown that DC pulsed with either defined mRNA of tumor antigen (Ag) such as α-fetoprotein (AFP), or total RNA of hepatocellular carcinoma (HCC) could elicit Ag-specific cytotoxic T lymphocyte (CTL) response. Therefore, we suggested a novel DC-based therapeutic method, in which DCs derived from CD34⁺ cells enriched peripheral blood mononuclear cells were pulsed with liposome-coated AFP and mutant P53 (mtP53) fused gene pEGFP-C3/AFP-mtP53 to induce bi-targeted specific CTL responses against HCC. Three different genotype HCC cell lines, HepG2 (human histocompatibility leukocyte antigens (HLA) A2 positive, AFP expressing positive, P53 expressing negative), SMMC7721 (HLA A2 positive, neither AFP nor P53 expressing positive), and HMCC97 (HLA A2 positive, both AFP and P53 expressing positive) were selected as targets for CTL responses. An important finding was that DCs pulsed with the liposome-coated fused gene could evoke more intensive bi-targeted Ag-specific CTL responses against HMCC97 than DCs pulsed with either AFP or P53 single gene ( P <  0.05). This experimental therapeutic model provides a new promising cytotherapeutic approach, in that DCs pulsed with the fused gene of different Ags might induce more extensive multitargeted antitumor immunity. ( Cancer Sci 2008; 99: 1420–1426)     

Tumor lysate and IL-18 loaded dendritic cells elicits Th1 response,tumor-specific CD8+ cytotoxic T cells in patients with malignant glioma

In this study, we demonstrate that tumor lysate-loaded dendritic cells can elicit a specific CD8+ cytotoxic T lymphocyte response against autologous tumor cells in patients with malignant glioma. CTL from three of five patients expressed strong cytolytic activity against autologous glioma cells, did not lyse autologous lymphoblasts and were variably cytotoxic against the LAK-sensitive cell line Daudi. Also, DCs pulsed normal brain lysate failed to induce cytolytic activity against autologous glioma cells, suggesting the lack of autoimmune response. Two of five patients CD8+ T cells expressed a modest cytotoxicity against autologous glioma cells. CD8+ T cells isolated during these ineffective primings secreted large amounts of IL-10, less amounts of IFN-γ as detected by ELISA, Type 2 bias in the CD8+ T cell response accounts for the lack of cytotoxic effector function from these patients. Cytotoxicity against autologous glioma cells could be significantly inhibited by anti-HLA class I antibody. These data demonstrate that tumor lysate-loaded DC can be an effective tool in inducing glioma-specific CD8+ CTL able to kill autologous glioma cells in vitro. However, high levels of tumor specific tolerance in some patients may account for a significant barrier to therapeutic vaccination. Moreover, cytotoxic responses were augmented by transfecting DC with the gene for IL-18. For all five patients, CD8+T cells treated with IL18 transfected DC produced Th1 response. These results may have important implications for the treatment of malignant glioma patients with immunotherapy. DCs loaded with total tumor lysate and IL-18 may represent a method for inducing Th1 immunoresponses against the entire repertoire of glioma antigens.     

Lentivirally engineered dendritic cells activate AFP-specific T cells which inhibit hepatocellular carcinoma growth in vitro and in vivo

α-fetoprotein (AFP), a tumor-associated antigen for hepatocellular carcinoma (HCC), is an established biomarker for HCC. In this study, we created a lentivirus expressing the AFP antigen and investigated the anti-tumor activity of AFP-specific CD8+ T cells, with and without CD4+ T cells, which were activated by either AFP peptide-pulsed or Lenti-AFP-engineered Dendritic cells (DCs) in vitro and in vivo. AFP-specific T cells could efficiently kill HepG2 HCC cells, and produced IL-2, IFN-γ, TNF-α, perforin and granzyme B, with minimal production of IL-10 (a negative regulator of T cell activation). Both strategies activated AFP-specific T cells, but the lentiviral strategy was superior by several measures. Data also support an impact of CD4+ T cells in supporting anti-tumor activity. In vivo studies in a xenograft HCC tumor model also showed that AFP-specific T cells could markedly suppress HCC tumor formation and morbidity in tumor-bearing nude mice, as well as regulate serum levels of related cytokines and anti-tumor molecules. In parallel with human in vitro T cell cultures, the in vivo model demonstrated superior anti-tumor effects and Th1-skewing with Lenti-AFP-DCs. This study supports the superiority of a full-length antigen lentivirus-based DCs vaccine strategy over peptides, and provides new insight into the design of DCs-based vaccines.     

树突状细胞诱导的细胞毒T淋巴细胞抑制移植瘤细胞增殖

目的　研究树突状细胞（ Ｄ Ｃ）体外诱导的细胞免疫能否抑制裸鼠移植瘤肿瘤细胞增殖。方法　联合应用粒／巨细胞集落刺激因子（ Ｇ Ｍ  Ｃ Ｓ Ｆ）及白介素４（ Ｉ Ｌ４）直接从肝癌患者外周血中培养出 Ｄ Ｃ;以源于人肝癌细胞系 Ｈｅｐ Ｇ２ 细胞的肿瘤抗原粗提物刺激 Ｄ Ｃ; Ｄ Ｃ 激活同源的 Ｔ 淋巴细胞产生细胞 毒性 Ｔ 淋 巴细胞 （ Ｃ Ｔ Ｌ）; 建立 人肝癌 细胞 系 Ｈｅｐ Ｇ２ 裸鼠移植瘤模型; Ｃ Ｔ Ｌ 治疗人肝癌细胞系 Ｈｅｐ Ｇ２ 裸鼠移植瘤;检测移植瘤标本肿瘤细胞 Ｐ Ｃ Ｎ Ａ 表达水平。结果　 Ｄ Ｃ诱导的 Ｃ Ｔ Ｌ抑制 Ｈｅｐ Ｇ２ 裸鼠移植瘤细胞增殖从而抑制移植瘤生长。结论　经肿瘤抗原激活的 Ｄ Ｃ 作为一新概念上的抗肿瘤疫苗有可能在肿瘤的治疗中发挥重要作用。     

树突状细胞与肿瘤疫苗治疗

树突状细胞(dendriticcells,DC)是人体内功能最强大的专职抗原递呈细胞,是肿瘤免疫反应中不可缺少的辅助细胞。未成熟DC可摄取抗原,当有危险信号刺激时可迁徙至淋巴器官,并递呈抗原给T细胞进而激发免疫应答。目前普遍采用的获取DC的方法是对外周血单核细胞(PBMC)进行体外诱导和培养。证据显示DC浸润与许多恶性肿瘤的预后有关。DC数量减少和功能缺陷,也是肿瘤细胞逃避机体免疫监视的机制之一。用于装载DC的抗原包括肿瘤细胞或肿瘤细胞提取物、肿瘤抗原蛋白、肿瘤抗原肽、肿瘤抗原DNA/RNA等。肿瘤抗原经脂质体介导在体内转染DC,也可激发特异性免疫应答。     

Presentation of renal tumor antigens by human dendritic cells activates tumor-infiltrating lymphocytes against autologous tumor: implications for live kidney cancer vaccines.

The clinical impact of dendritic cells (DCs) in the treatment of human cancer depends on their unique role as the most potent antigen-presenting cells that are capable of priming an antitumor T-cell response. Here, we demonstrate that functional DCs can be generated from peripheral blood of patients with metastatic renal cell carcinoma (RCC) by culture of monocytes/macrophages (CD14+) in autologous serum containing medium (RPMI) in the presence of granulocyte macrophage colony-stimulating factor and interleukin (IL) 4. For testing the capability of RCC-antigen uptake and processing, we loaded these DCs with autologous tumor lysate (TuLy) using liposomes, after which cytometric analysis of the DCs revealed a markedly increased expression of HLA class I antigen and a persistent high expression of class II. The immunogenicity of DC-TuLy was further tested in cultures of renal tumor infiltrating lymphocytes (TILs) cultured in low-dose IL-2 (20 Biologic Response Modifier Program units/ml). A synergistic effect of DC-TuLy and IL-2 in stimulating a T cell-dependent immune response was demonstrated by: (a) the increase of growth expansion of TILs (9.4-14.3-fold; day 21); (b) the up-regulation of the CD3+ CD56- TcR+ (both CD4+ and CD8+) cell population; (c) the augmentation of T cell-restricted autologous tumor lysis; and (d) the enhancement of IFN-gamma, tumor necrosis factor-alpha, granulocyte macrophage colony-stimulating factor, and IL-6 mRNA expression by TILs. Taken together, these data implicate that DC-TuLy can activate immunosuppressed TIL via an induction of enhanced antitumor CTL responses associated with production of Thl cells. This indicates a potential role of DC-TuLy vaccines for induction of active immunity in patients with advanced RCC.     

Apoptotic pancreatic tumor cells are superior to cell lysates in promoting cross-priming of cytotoxic T cells and activate NK and gammadelta T cells

Tumor vaccines using dendritic cells (DCs) have been shown to induce antitumor CTL responses. The choice of the tumor antigen preparation used for DC loading is still an unresolved issue. We compared DCs pulsed with cell lysates, whole apoptotic tumor cells or their supernatants of the HLA-A2(+) human pancreatic carcinoma cell line Panc-1 for their capacity to activate T cells. Monocyte-derived DCs from HLA-A2(+) donors were pulsed with tumor antigen, matured subsequently, and cocultured with autologeous peripheral blood mononuclear cells. After three weekly restimulations with DCs, T-cell activation was assessed by intracellular IFN-gamma staining and cytotoxicity assays. Compared with lysate, pulsing DCs with the supernatant of apoptotic tumor cells induced a higher frequency of activated CTLs and T-helper cells, as well as an enhanced MHC class I-restricted tumor cell lysis. No activation of natural killer (NK) or gammadelta T cells was detected. Pulsing DCs with whole apoptotic tumor cells induced an even more pronounced lytic effect. However, in this case, MHC class-I blocking was only partially effective, and unrelated cell lines were also killed. IFN-gamma staining revealed activation of CTLs and T-helper cells, as well as NK and gammadelta T cells. Trans-well cultures of NK cells, apoptotic tumor cells, and DCs showed that NK cell activation was dependent on direct cell-to-cell contact with tumor cells and the presence of interleukin-12 produced by DCs. These results indicate that the choice of antigen preparation is a critical determinant in the induction of antitumor immunity. Tumor vaccines consisting of DCs and apoptotic tumor cells may be able to activate CTLs, as well as effector cells of the innate immune system.     

细胞因子IL-7与IL-15联合优化胃癌EBV特异性CTL细胞培养体系

目的:探讨细胞因子白细胞介素-7（IL-7）和IL-15在胃癌EB病毒（EBV）抗原特异性细胞毒性T细胞（CTLs）培养中较IL-2的优势。方法:提取胃癌患者外周血单个核细胞贴壁培养2 h,贴壁细胞加IL-4和粒细胞-巨噬细胞集落刺激因子（GM-CSF）诱导树突状细胞（DC）,成熟的DC负载EBV抗原肽与T细胞混合培养,诱导EBV-CTLs,比较在细胞因子IL-2或IL-7/15培养条件下诱导的EBV-CTLs的扩增能力、表型、免疫应答及体外杀伤能力的差别。结果:与细胞因子IL-2相比较,IL-7联合IL-15培养的EBV-CTLs细胞中含有较高比例的CD3+ T细胞［（91.2±1.5）% vs （80.8±1.6）%,P=0.008 4］以及较高比例的CD3+CD8+ T细胞［（66.8±2.3）% vs （30.17±6.9）%,P=0.007 6］;在维持中央记忆性T细胞扩增方面,IL-7联合IL-15扩增的EBV-CTLs细胞中含有较高比例的CD8+CD62L+ T细胞［（26.4±2.3）% vs （9.6±1.4）%,P=0.003 6］及CD8+CD27+ T细胞［（38.5±3.7）% vs （16.7±2.9）%,P=0.01］;在免疫应答能力方面,接触DC负载抗原肽24 h后,IL-7联合IL-15培养的EBV-CTLs能分泌更多的γ干扰素（IFN-γ）,且CD137上调明显高于IL-2组;在体外杀伤实验中,IL-7联合IL-15诱导的EBV-CTLs对表达EBV抗原的靶细胞表现出更强的杀伤作用。结论:IL-7联合IL-15在扩增胃癌抗原特异性EBV-CTLs方面具有优势,扩增的细胞中含有较高比例的CD3+CD8+ T细胞,且能维持中央记忆性T细胞的扩增,表现出有更强的免疫应答和体外抗肿瘤效果,为其进一步临床个体化治疗 EBV阳性胃癌提供客观实验依据。     

Generation of tumor-specific T-lymphocytes by cross-priming with human dendritic cells ingesting apoptotic tumor cells

It has been suggested that dendritic cells (DCs) are capable of ingesting apoptotic tumor cells (ATCs) and presenting tumor-associated antigens to immune cells. We evaluated the potential of human DCs, which have ingested ATCs, to serve as a source of antigenic epitopes for presentation to T cells specific for PCI-13, a squamous cell carcinoma of the head and neck cell line. Immature DCs (DCimm) generated in the presence of interleukin 4 and granulocyte machrophage colony-stimulating factor from peripheral blood monocytes of HLA-A2+ healthy donors were incubated in the presence of ATCs. Uptake of ATCs by DCs was monitored by flow cytometry and confocal microscopy after 2-18 h of coincubation. When DCs were matured (DCmat) in the presence of proinflammatory cytokines, their capacity to uptake ATCs was reduced. Responses of PCI-13-specific CD8+ T cells to unmodified PCI-13 cells and to DCimm or DCmat +/- ATCs or +/- tumor lysates were tested in gamma-IFN enzyme-linked immunospot and cytotoxicity assays. Unmodified tumor cells were found to be the best stimulators of antitumor activity of the established T-cell line, and ATCs alone were minimally stimulatory. However, DCs that ingested ATCs were able to present tumor antigens to CTLs, and DCimm and DCmat were almost equally stimulatory. When DCs plus various tumor-derived preparations were used as antigen-presenting cells with autologous HLA-A2+ T cells obtained from normal donors, DCs that had ingested ATCs were more effective in generating CD8+ CTLs than tumor cells alone or DCs pulsed with tumor lysates. The results indicate that human DCs fed with ATCs and then matured effectively generated T cell-mediated antitumor responses in vitro.     

树突状细胞体外诱导抗肿瘤免疫通过诱导肿瘤细胞凋亡抑制裸鼠移植瘤生长

研究树突状细胞（ＤＣ）体外诱导的细胞免疫抑制裸鼠移植瘤生长作用及其机理。方法：联合应用粒／巨噬细胞集落刺激因子ＫＭ－ＣＳＦ）及白介素－４（ＩＬ－４）直接从肝癌患者外周血中培养出ＤＣ,以人肝癌细胞系ＨｅｐＧ２肿瘤细胞的肿瘤抗原粗提物刺激ＤＣ,ＤＣ激活同源的Ｔ淋巴细胞,建立裸鼠人肝癌细胞系ＨｅｐＧ２移植瘤模型,以被激活的Ｔ淋巴细胞治疗裸鼠ＨｅｐＧ２移植瘤并观察治疗效果,检测移植瘤标本肿瘤细胞凋亡情况。结果：ＤＣ诱导的Ｔ细胞免疫能够诱导裸鼠人肝癌细胞系ＨｅｐＧ２移植瘤肿瘤细胞大量凋亡从而抑制裸鼠ＨｅｐＧ２移植瘤生长。结论：经肿瘤抗原激活的ＤＣ作为一新概念上的抗肿瘤疫苗有可能在肿瘤的治疗中发挥重要作用。     

树突状细胞体外诱导抗肝癌免疫抑制裸鼠人肝癌细胞系HepG2移植瘤发生与生长

为研究树突状细胞(DC)体外诱导抗肿瘤免疫能否预防裸鼠移植瘤发生及抑制裸鼠移植瘤生长,联合应用粒/巨噬细胞集落刺激因子(GM-CSF)及白介素4(IL-4)直接从肝癌患者外周血中培养出DC;以源于人肝癌细胞系HepG2的肿瘤抗原粗提物刺激DC,DC激活同源的T淋巴细胞;以被激活的T淋巴细胞预防性接种于裸鼠皮下,观察进一步接种的人肝癌细胞系HepG2移植瘤发生;观察被激活的T淋巴细胞抑制已接种于裸鼠的人肝癌细胞系HepG2移植瘤生长.发现,DC诱导的抗肿瘤免疫不仅能预防裸鼠人肝癌细胞系HepG2移植瘤发生,而且能抑制该移植瘤生长.提示经肿瘤抗原激活的DC作为一新概念上的抗肿瘤疫苗有可能在肝癌的预防及治疗中发挥重要作用.     

Vaccination with tumor lysate-pulsed dendritic cells elicits antigen-specific, cytotoxic T-cells in patients with malignant glioma

The primary goal of this Phase I study was to assess the safety and bioactivity of tumor lysate-pulsed dendritic cell (DC) vaccination to treat patients with glioblastoma multiforme and anaplastic astrocytoma. Adverse events, survival, and cytotoxicity against autologous tumor and tumor-associated antigens were measured. Fourteen patients were thrice vaccinated 2 weeks apart with autologous DCs pulsed with tumor lysate. Peripheral blood mononuclear cells were differentiated into phenotypically and functionally confirmed DCs. Vaccination with tumor lysate-pulsed DCs was safe, and no evidence of autoimmune disease was noted. Ten patients were tested for the development of cytotoxicity through a quantitative PCR-based assay. Six of 10 patients demonstrated robust systemic cytotoxicity as demonstrated by IFN-gamma expression by peripheral blood mononuclear cells in response to tumor lysate after vaccination. Using HLA-restricted tetramer staining, we identified a significant expansion in CD8+ antigen-specific T-cell clones against one or more of tumor-associated antigens MAGE-1, gp100, and HER-2 after DC vaccination in four of nine patients. A significant CD8+ T-cell infiltrate was noted intratumorally in three of six patients who underwent reoperation. The median survival for patients with recurrent glioblastoma multiforme in this study (n = 8) was 133 weeks. This Phase I study demonstrated the feasibility, safety, and bioactivity of an autologous tumor lysate-pulsed DC vaccine for patients with malignant glioma. We demonstrate for the first time the ability of an active immunotherapy strategy to generate antigen-specific cytotoxicity in brain tumor patients.     

In vivo induction of dendritic cell-mediated cytotoxicity against allogeneic pancreatic carcinoma cells

The objective of this study was to assess the toxicity and immunological response induced by autologous dendritic cells (DCs) pulsed with allogeneic tumor lysate in a pancreatic cancer patient. The lack of available tumor peptides in pancreatic cancer strongly supports the idea to use allogeneic tumor cells as a source of antigens. The patient suffering from a stage IV pancreatic cancer received 1-2x10(7) autologous monocyte-derived DCs in three-week intervals injected into a groin lymph node. Monocytes from peripheral blood were isolated by magnetic bead selection. For the first ten vaccinations DCs were loaded with autologous tumor cell lysate obtained during surgical exploration. After consumption of the autologous lysate, equal numbers of DCs were pulsed with lysate of the tumor cell line AsPc-1 and BxPc-3 for a further five vaccinations. Peripheral mononuclear cells (PMNCs) were harvested after the seventh and compared with PMNCs obtained after the fourteenth vaccination for immunological response. Delayed type hypersensitivity reactivity to DCs pulsed with autologous and allogeneic tumor lysate was also assessed. The patient received a total of fifteen vaccinations. There was no toxicity or evidence of autoimmunity observed. Delayed type hypersensitivity was found to be positive for the autologous as well as the allogeneic tumor lysate pulsed DCs. in vitro cytotoxicity assays demonstrated a dramatic increase of the PMNC killing capacity against the pancreatic cancer cell lines AsPc-1 and BxPc-3 after the fourteenth compared to the seventh vaccination. CT scans revealed a stable disease for six months. The administration of autologous DCs pulsed with allogeneic tumor lysate is non-toxic and suitable for inducing an immunological anti-tumor response. Even though this study was confined to a single patient, the data might open a door for novel immunotherapeutical strategies.