白介素12基因修饰的树突细胞疫苗治疗自发性转移性肺癌

背景与目的:对转移性肺癌的治疗已进行了大量研究,但仍缺乏有效的治疗方法。本研究目的是探讨白介素12(IL-12)基因修饰的树突细胞(DC)疫苗对自发性转移性肺癌的治疗作用。方法:小鼠足垫注射3LLLewis肺癌细胞,建立自发性转移性肺癌模型,经IL-12基因修饰、3LL特异抗原多肽Mut1体外致敏DC疫苗(DC-IL-12/Mut1)皮下免疫2次,观察荷瘤鼠肺重量、肺表面转移结节数量、存活期及相应免疫指标的变化,组间差异行t检验,生存期行时序检验。结果:与对照组(DC-LacZ/Mut1)相比,DC-IL-12/Mut1组肺重量轻、肺表面转移结节数量少、存活期长(P<0.01),细胞毒性T淋巴细胞(CTL)活性和NK活性增强(P<0.01)。结论:IL-12基因修饰的DC疫苗对自发性转移性肺癌有明显的治疗作用,其可能机理是诱导特异性CTL和增强NK活性。     

Improving efficacy of interleukin-12-transfected dendritic cells injected into murine colon cancer with anti-CD137 monoclonal antibodies and alloantigens

Intralesional administration of cultured dendritic cells (DCs) engineered to produce IL-12 by in vitro infection with recombinant adenovirus frequently displays eradicating efficacy against established subcutaneous tumors derived from the CT26 murine colon carcinoma cell line. The elicited response is mainly mediated by cytolytic T lymphocytes. In order to search for strategies that would enhance the efficacy of the therapeutic procedure against less immunogenic tumors, we moved onto malignancies derived from the inoculation of MC38 colon cancer cells that are less prone to undergo complete regression upon a single intratumoral injection of IL-12-secreting DCs. In this model, we found that repeated injections of such DCs, as opposed to a single injection, achieved better efficacy against both the injected and a distantly implanted tumor; that the use of semiallogeneic DCs that are mismatched in one MHC haplotype with the tumor host showed slightly better efficacy; and that the combination of this treatment with systemic injections of immunostimulatory anti-CD137 (4-1BB) monoclonal antibody achieved potent combined effects that correlated with the antitumor immune response measured in IFN-gamma ELISPOT assays. The elicited systemic immune response eradicates concomitant untreated lesions in most cases. Curative efficacy was also found against some tumors established for 2 weeks when these strategies were used in combination. These are preclinical pieces of evidence to be considered in order to enhance the therapeutic benefit of a strategy that is currently being tested in clinical trials. Supplementary Material for this article can be found on the International Journal of Cancer website at http://www.interscience.wiley.com/jpages/0020-7136/suppmat/index.html.     

Fusion hybrid of dendritic cells and engineered tumor cells expressing interleukin-12 induces type 1 immune responses against tumor

AIMS AND BACKGROUND: Dendritic cell (DC)-tumor fusion hybrid vaccinees that facilitate antigen presentation represent a novel powerful strategy in cancer immunotherapy. Preclinical studies have demonstrated that IL-12 promotes specific antitumor immunity mediated by T cells in several types of tumors. In the present study, we investigated the antitumor immunity derived from vaccination of fusion hybrids between DCs and engineered J558/IL-12 myeloma cells secreting Th1 cytokine IL-12. METHODS: The expression vector pcDNA-IL-12 was generated and transfected into J558 myeloma cells and then bone marrow-derived DCs were fused with engineered J558/IL-12 cells. The antitumor immunity derived from vaccination of the fusion hybrid DC/J558/IL-12 was evaluated in vitro and in vivo. RESULTS: DC/J558/IL-12 cells secreted recombinant IL-12 (1.6 ng/mL), and inoculation of BALB/c mice with DC/J558/IL-12 hybrid induced a Th1 dominant immune response and resulted in tumor regression. Immunization of mice with engineered DC/J558/IL-12 hybrid elicited stronger J558 tumor-specific cytotoxic T lymphocyte (CTL) responses in vitro as well as more potent protective immunity against J558 tumor challenge in vivo than immunization with the mixture of DCs and J558/IL-12, J558/IL-12 and J558, respectively. Furthermore, the anti-tumor immunity mediated by DC/J558/IL-12 tumor cell vaccination in vivo appeared to be dependent on CD8+ CTL. CONCLUSIONS: These results demonstrate that the engineered fusion hybrid vaccines that combine Th1 cytokine gene-modified tumor cells with DCs may be an attractive strategy for cancer immunotherapy.     

光动力法制备DC胶质瘤疫苗抗肿瘤作用的研究

目的:研究光动力法(photodynamic therapy,PDT)处理后,用酸洗法获取C6胶质瘤细胞的抗原肽,制备树突状细胞(dendritic cell,DC)疫苗,诱导细胞毒性T淋巴细胞(cytotoxic T lymphocyte,CTL)在体外杀伤C6细胞的活性,以及PDT对C6胶质瘤细胞免疫原性的直接影响。方法:自大鼠骨髓分离DC前体细胞于体外诱导、扩增获得成熟DC。C6细胞经PDT处理后,对尚贴壁的细胞以酸洗法获取其表面抗原,从上清液中提取全细胞抗原,未作PDT处理的C6细胞以酸洗或冻融法提取抗原。分别以这4种抗原致敏DC,制成DC疫苗接种SD大鼠后,取脾作CTL的体外杀伤活性测定。结果:用PDT处理后酸洗法获得的抗原刺激DC成熟的能力最强,它制备的DC疫苗诱导的CTL的体外杀伤率最高,为(95.5±1.6)%,而光照后上清组为(90.2±2.4)%,酸洗组为(73.3±2.7)%,冻融组为(63.6±4.9)%,PBS对照组为0。结论:PDT能直接增强肿瘤细胞的免疫原性,用酸洗法获取PDT处理后的肿瘤细胞的抗原肽制备DC疫苗是一种有前景的新方法。     

低剂量安素泰联合树突状细胞治疗小鼠肺癌的疗效研究

目的：探讨低剂量化疗联合树突状细胞治疗小鼠肺源性肿瘤的疗效。方法：皮下注射3LL肿瘤细胞予小鼠体内,成瘤后分成4个治疗组,即对照组、低剂量安素泰治疗组、DC免疫治疗组、低剂量安素泰联合DC免疫治疗组,分别测量各组肿瘤面积;应用免疫组化方法检测各组瘤体内CD4＋,CD8＋的T淋巴细胞的浸润;ELISA法检测小鼠引流淋巴结内IFN-γ的分泌。结果：低剂量安素泰联合DC免疫治疗组能有效地抑制肿瘤的生长,瘤床内CIM＋、CD8＋的T淋巴细胞浸润明显,引流淋巴结内分泌高水平的IFN-γ。结论：低剂量化疗联合DC免疫治疗能有效地抑制小鼠肺部肿瘤的生长。     

Administration route-dependent vaccine efficiency of murine dendritic cells pulsed with antigens

Dendritic cells (DCs) loaded with tumour antigens have been successfully used to induce protective tumour immunity in murine models and human trials. However, it is still unclear which DC administration route elicits a superior therapeutic effect. Herein, we investigated the vaccine efficiency of DC2.4 cells, a murine dendritic cell line, pulsed with ovalbumin (OVA) in the murine E.G7-OVA tumour model after immunization via various routes. After a single vaccination using 1 x 10(6)OVA-pulsed DC2.4 cells, tumour was completely rejected in the intradermally (i.d.; three of four mice), subcutaneously (s.c.; three of four mice), and intraperitoneally (i.p.; one of four mice) immunized groups. Double vaccinations enhanced the anti-tumour effect in all groups except the intravenous (i.v.) group, which failed to achieve complete rejection. The anti-tumour efficacy of each immunization route was correlated with the OVA-specific cytotoxic T lymphocyte (CTL) activity evaluated on day 7 post-vaccination. Furthermore, the accumulation of DC2.4 cells in the regional lymph nodes was detected only in the i.d.-and s.c.-injected groups. These results demonstrate that the administration route of antigen-loaded DCs affects the migration of DCs to lymphoid tissues and the magnitude of antigen-specific CTL response. Furthermore, the immunization route affects vaccine efficiency.     

Immunosuppressive effects of interleukin-12 coexpression in melanoma antigen gene-modified dendritic cell vaccines

Genetic immunotherapy with tumor antigen gene-modified dendritic cells (DC) generates robust immunity, although antitumor protection is not complete in all models. Previous experience in a model in which C57BL/6 mice immunized with DC transduced with adenoviral vectors expressing MART-1 demonstrated a 20-40% complete protection to a tumor challenge with B16 melanoma cells. Tumors that did develop in immunized mice had slower growth kinetics compared to tumors implanted in na?ve mice. In the present study, we wished to determine if the supraphysiological production of the Th1-skewing cytokine interleukin-12 (IL-12) could enhance immune activation and antitumor protection in this model. In a series of experiments immunizing mice with DC cotransduced with MART-1 and IL-12, antitumor protection and antigen-specific splenocyte cytotoxicity and interferon gamma production inversely correlated with the amount of IL-12 produced by DC. This adverse effect of IL-12 could not be explained by a direct cytotoxic effect of natural killer cells directed towards DC, nor the production of nitric oxide leading to down-regulation of the immune response - the two mechanisms previously recognized to explain immune-suppressive effects of IL-12-based vaccine therapy. In conclusion, in this animal model, IL-12 production by gene-modified DC leads to a cytokine-induced dose-dependent inhibition of antigen-specific antitumor protection.     

The boosting effect of co-transduction with cytokine genes on cancer vaccine therapy using genetically modified dendritic cells expressing tumor-associated antigen

The T-helper 1 (Th1) immune reaction is most important in dendritic cell (DC)-based immunotherapy. Interleukin 12 (IL-12) and granulocyte macrophage colony-stimulating factor (GM-CSF) play a pivotal role in inducing Th1 and cytotoxic T lymphocyte (CTL) responses. In this study, DCs expressing the natural tumor antigen gp70 of BALB/c-derived CT26 were adenovirally transduced with the IL-12 gene and/or GM-CSF gene, and it was examined whether vaccinations using these genetically engineered DCs can induce strong therapeutic antitumor immunity. Mice were immunized once by subcutaneous (s.c.) injection with genetically modified DCs. The cytotoxic activity of splenocytes against CT26 was assayed in a 51Cr-release assay 14 days after immunization. The therapeutic efficacy of the vaccination was examined in s.c. tumor models. The cytotoxic activity of CTLs against CT26 in mice immunized with DCs expressing gp70 (DC-AxCAgp70) was significantly augmented by co-transduction with the GM-CSF/IL-12 gene (p<0.0001) and remarkably reduced by the depletion of CD4+ or CD8+ cells (p<0.01). The cytotoxic activity against CT26 of the plain spleen cells in mice immunized with DC-AxCAgp70/GM-CSF/IL-12 was significantly higher than that in mice immunized with DC-AxCAgp70 (p<0.0001), and this activity decreased to almost 50% upon the depletion of NK cells. Vaccinations using DC-AxCAgp70/GM-CSF/IL-12 or DC-AxCAgp70/IL-12 could elicit potent therapeutic immunity in s.c. tumor models; tumor-free mice were observed in these vaccination groups. However, there was no significant difference between these two groups. A vaccination therapy using DCs co-transduced with the TAA gene and Th 1-type cytokine genes, especially the IL-12 gene, is ideal for immunotherapy in terms of the activation of DCs, NK cells, CD4+ T cells and CD8+ T cells, and may be useful in the clinical application of a cancer vaccine therapy.     

Construction of a recombinant adeno-associated virus (rAAV) vector expressing murine interleukin-12 (IL-12)

IL-12 is a heterodimeric cytokine that is known to induce tumor regression and long-term antitumor immunity. Recombinant adeno-associated virus (rAAV) vectors are advantageous for gene therapy in that they lack pathogenicity in humans, infect dividing as well as nondividing cells, and show a broad range of infectivity. We constructed an rAAV vector expressing interleukin-12 (IL-12) for cancer immunotherapy studies in a mouse model by inserting murine IL-12 (mIL-12) p35 and p40 cDNAs into the plasmid pRep4 and inserting the encephalomyocarditis virus internal ribosomal entry site between the p35 and p40 cDNAs. The mIL-12 expression cassette containing the Rous sarcoma virus promoter and a simian virus 40 polyadenylation signal was subcloned into the AAV plasmid p008Sub/NeoR, which contains two AAV inverted terminal repeat sequences and the NeoR gene driven by the thymidine kinase promoter. rAAV virions (10(4) infectious particles/ml) were generated by cotransfection of rAAV-mIL-12 and a helper plasmid (pAAV/Ad) into 293 cells previously infected with adenovirus 5. After infection of D6 fibroblasts with rAAV-mIL-12, G418-resistant clones were isolated. Each of the 1D D6 clones isolated produced up to 5.2 ng/10(6) cells/48 hours of mIL-12 as determined by enzyme-linked immunosorbent assay. Induction of interferon-gamma, enhanced lymphocyte proliferation, and cytotoxicity assays confirmed biologically functional IL-12 production by the vector. This is the first report indicating that an rAAV vector expresses mIL-12, which can be used to model the effects of mIL-12 alone and/or in combination with other antitumor agents.     

Anti-tumor efficacy of gene vaccine expressing PSMA

Objective  

To observe anti-tumor eff ects of PVAX-PSMA gene vaccine.     

树突细胞-食管癌融合细胞体外诱导特异性抗食管癌免疫反应

背景与目的:树突细胞(dendritic cells,DC)是人体专职的抗原呈递细胞,以DC为基础的DC/肿瘤细胞融合疫苗可以有效地诱导特异性抗肿瘤免疫应答.本研究旨在探讨成熟的DC与人食管癌细胞株ECl09细胞融合疫苗体外诱导特异性抗食管癌细胞的免疫反应.方法:从健康志愿者外周血中分离出单个核细胞(peripheral blood mononuclear cells,PBMC),在重组人粒/巨噬细胞集落刺激因子(recombinant human granulocyte-macrophage-colony-stimulating factor,rhGM-CSF)和白介素(interleukin-4,IL-4)作用下体外诱导DC,采用聚乙二醇(polyethylene glyco1,PEG)融合法使DC与EC109细胞融合制备DC/EC109细胞融合疫苗,四甲基偶氮唑盐(MTT)实验检测融合疫苗刺激T淋巴细胞增殖的活性,乳酸脱氢酶(LDH)实验检测融合疫苗活化的细胞毒性T淋巴细胞(cytotoxic T lymphocyte,CTL)在体外特异性杀伤EC109细胞的活性,并与对人胃癌细胞株SGC7901及人乳腺癌细胞株MCF7的杀伤作用进行比较.结果:DC与EC109细胞的融合效率最高达到22.25%.DC/EC109细胞融合疫苗能有效地刺激T淋巴细胞的增殖反应,其刺激T淋巴细胞增殖的能力显著高于DC或EC109细胞(P＜0.05).DC/EC109细胞融合疫苗活化的CTL对EC109细胞具有特异性的杀伤作用,对EC109细胞的杀伤作用显著强于对SGC7901细胞及MCF7细胞的杀伤作用(P＜0.05).结论:DC/EC109细胞融合疫苗能有效诱导抗EC109细胞的特异性免疫应答.     

Improved efficacy of dendritic cell vaccines and successful immunization with tumor antigen peptide‐pulsed peripheral blood mononuclear cells by coadministration of recombinant murine interleukin‐12

The well‐characterized P815 tumor model was used to optimize anti‐tumor immunization approaches in mice. Tumor peptides derived from antigens P198 or P1A were targeted to antigen‐presenting cells (APC) by ex vivo pulsing. Initial experiments with irradiated pulsed splenic dendritic cells (sDC) injected weekly in the hind footpads for 3 weeks demonstrated cytolytic T lymphocyte (CTL) generation in 10–20% of mice. Because of the importance of interleukin‐12 (IL‐12) in tumor rejection responses, pulsed sDCs also were given together with recombinant murine IL‐12 (rmIL‐12). This strategy induced peptide‐specific CTL in 100% of the mice. The IL‐12 had to be injected in the footpads on days 0, 1 and 2 of each immunization week to achieve an optimal effect. The improvement seen with the addition of IL‐12 prompted examination of other sources of APC. Purified resting B cells, lipopolysaccharide (LPS) blasts and non‐fractionated splenocytes or peripheral blood mononuclear cells (PBMC) were pulsed with peptide and administered with the same schedule of rmIL‐12. Because these cell types appeared to bind peptides less avidly than did DC, increasing peptide doses were used during pulsing. Interestingly, immunization with each of these APC also induced specific CTL in 100% of mice, provided rmIL‐12 was coadministered. CTLs were detected both in the spleen and in the peripheral blood. Immunization with irradiated, P1A‐pulsed PBMC plus rmIL‐12 resulted in protection against challenge with tumors expressing the specific antigen in all mice. The ease by which human patient PBMCs can be prepared provides a straightforward vaccination approach to be used in clinical trials of peptide‐based immunization in melanoma. Int. J. Cancer 80:324–333, 1999. © 1999 Wiley‐Liss, Inc.     

Progenipoietin-generated dendritic cells exhibit anti-tumor efficacy in a therapeutic murine tumor model

Progenipoietin (ProGP-4) is a chimeric molecule, exhibiting both Flt-3 and granulocyte-colony stimulating factor (G-CSF) receptor agonist activities. Subcutaneous administration of ProGP-4 to BALB/c mice at a dose of 40-100 microg/day for up to 12 consecutive days induces both CD11c(+) dendritic cells (DCs) and CD11c(-)/CD11b(+) granulocytes in spleen, blood and lymph nodes of treated animals. Peak numbers of all cell populations were observed on day 7 of treatment, with CD11c(+) DCs representing approximately 8% of total splenocytes at that time. Approximately 40-50% of these CD11c(+) cells were also able to endocytose and process the exogenous fluorescent antigen DQ-BSA. As a test of their therapeutic utility, freshly prepared CD11c(+) DCs were pulsed with a defined tumor-associated peptide epitope (murine p53(232-240)) and injected as a vaccine into BALB/c mice bearing day 7 established CMS4 sarcomas. Similarly prepared DCs were injected again 1 week later. Based on our results, we conclude that (i) both peptide-pulsed CD11c(+) DCs (harvested directly from ProGP-4 treated mice) and pulsed bone marrow-derived DCs effectively slow the growth of or mediate the regression (in 25 of 89 [28%] cases) of CMS4 tumors, and (ii) nonpulsed DCs mediated minimal or no therapeutic effect. These data support the ability of ProGP-4 to enhance the peripheral frequencies of DCs that exhibit therapeutic efficacy when applied as a vaccine to treat tumor-bearing animals.     

Hyperthermia-induced shedding and masking of melanoma-associated antigen

Hyperthermia has been reported to induce a dose-dependent reduction in the expression of melanoma-associated surface antigens. The objective of the present work was to study the mechanisms for the reduction in the expression of the p250 antigen recognized by the monoclonal antibody 9.2.27. Measurements at 37°C showed that antibody binding induced a certain degree of modulation (internalization) of the melanoma-associated antigen. Masking of the antigen due to internalization and/or damage in situ, as well as shedding of the antigen, were measured after hyperthermia, and found to increase in a heat-dose-dependent manner, although for antigen masked this increase was not significant compared with control cells at 37°C. The sum of antigen shed and masked after hyperthermia correlated with the overall reduction in antigen expression measured independently. During hyperthermia, antigen was shed and masked in approximately equal amounts. After the treatment, hyperthermia-induced shedding continued as a function of time and caused a further reduction in antigen expression, but masking did not differ from 37°C controls.     

Biodistribution and vaccine efficiency of murine dendritic cells are dependent on the route of administration.

Dendritic cells (DCs) are professional antigen-presenting cells, well equipped to initiate an immune response. Currently, tumor antigen-derived peptide loaded DCs are used in clinical vaccination in cancer patients. However, the optimal dose and route of administration of a DC vaccine still remain to be determined. Using indium-111-labeled DCs, we investigated whether the route of administration does affect the biodistribution of DCs in lymphoid organs and whether it influences the outcome of DC vaccination in the B16 mouse melanoma tumor model. The results demonstrate that i.v. injected DCs mainly accumulate in the spleen, whereas s.c. injected DCs preferentially home to the T-cell areas of the draining lymph nodes. Using tyrosinase-related protein-2-derived peptide-loaded DC vaccination in a fully autologous B16 melanoma tumor model, we observed a delay in tumor growth, improved survival as well as increased antitumor cytotoxic T-cell reactivity after s.c. vaccination as compared to i.v. vaccination. These data demonstrate that optimal induction of antitumor reactivity against the autologous melanocyte differentiation antigen tyrosinase-related protein-2-derived peptide occurs after s.c. vaccination and correlates with the preferential accumulation of DCs in the T-cell areas of lymph nodes.     

IL-23基因修饰的树突细胞疫苗联合β-榄香烯对小鼠胰腺癌生长的影响

背景与目的:树突细胞(dendriticcells,DC)疫苗是目前最具应用潜能的治疗性疫苗,功能性细胞因子能显著增强DC的活性及其诱导的宿主抗肿瘤作用,利用细胞因子基因修饰DC是当今肿瘤免疫治疗中最活跃的领域。本研究探讨β-榄香烯联合白细胞介素-23(interleukin-23,IL-23)修饰的DC疫苗对胰腺癌小鼠的协同抗肿瘤作用。方法:克隆并构建IL-23基因真核双表达载体,转染DC并负载肿瘤抗原后制备成疫苗。将IL-23基因转染的DC疫苗、空质粒转染的DC疫苗、未转染的DC疫苗及对照生理盐水分别注射小鼠,体外观察各组小鼠脾脏T淋巴细胞IFN-γ及IL-4的分泌。体内观察β-榄香烯联合DC疫苗对荷胰腺癌小鼠肿瘤生长的抑制作用及对小鼠存活期的影响。结果:基因测序证实IL-23基因克隆及双表达载体构建成功,转染后DC共刺激分子MHC-Ⅰ和MHC-Ⅱ的表达增强。接种IL-23转染DC疫苗后小鼠的免疫防御能力显著增强,有效地延缓并防御接种肿瘤的发生。DC介导的免疫应答促进了IFN-γ生成型Th1细胞的产生,未转染DC疫苗组和空质粒转染DC疫苗组IL-4分泌量与IL-23转染的DC疫苗组比较差异有显著性(P<0.05);IL-23转染DC疫苗组IFN-γ的分泌与其他各组比较差异有显著性(P<0.01)。β-榄香烯联合IL-23转染DC疫苗组肿瘤生长受到显著抑制,该组小鼠存活期与DC组、NS对照组及β-榄香烯组比较差异有极显著性(P<0.01)。结论:IL-23修饰DC疫苗可强化宿主针对特异肿瘤的Th1及CTL的免疫应答,使宿主不仅产生防御性免疫反应而且增强自动免疫能力。β-榄香烯有一定的协同抗癌作用。     

Hyperthermia-induced shedding and masking of melanoma-associated antigen

Hyperthermia has been reported to induce a dose-dependent reduction in the expression of melanoma-associated surface antigens. The objective of the present work was to study the mechanisms for the reduction in the expression of the p250 antigen recognized by the monoclonal antibody 9.2.27. Measurements at 37 degrees C showed that antibody binding induced a certain degree of modulation (internalization) of the melanoma-associated antigen. Masking of the antigen due to internalization and/or damage in situ, as well as shedding of the antigen, were measured after hyperthermia, and found to increase in a heat-dose-dependent manner, although for antigen masked this increase was not significant compared with control cells at 37 degrees C. The sum of antigen shed and masked after hyperthermia correlated with the overall reduction in antigen expression measured independently. During hyperthermia, antigen was shed and masked in approximately equal amounts. After the treatment, hyperthermia-induced shedding continued as a function of time and caused a further reduction in antigen expression, but masking did not differ from 37 degrees C controls.     

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.