转染癌胚抗原基因的人树突状细胞疫苗表达的研究

目的 探索使用质粒转导制备转基因DCs疫苗的方法。方法 采用细胞因子rhIL-4和rhGM—CSF诱导培养法制备人外周血树突状细胞，用Lipofectine向人DCs转染含人CEA真核表达质粒。结果 转染组DCs培养上清CEA含量明显高于末转染组培养上清CEA含量。结论 人CEA真核表达质粒转染DCs可内源性表达CEA。     

CEA mRNA转染的成熟树突状细胞体外诱导特异性抗肿瘤作用

目的:将体外转录的癌胚抗原(carcinoembryonic antigen,CEA)mRNA转染入成熟树突状细胞(dendritic cell,DCs),观察其体外诱导的特异性抗肿瘤作用。方法:GM-CSF、IL-4、TNF-α体外诱导成熟DCs并用流式鉴定。构建pcDNA3.1-CEA载体,体外转录为CEA mRNA,电穿孔法将CEA mRNA转染入DCs。流式细胞术检测转染后DCs中CEA蛋白的表达;MTT法检测DCs刺激T细胞增殖能力;LDH法检测DCs体外诱导的CTL的特异性抗肿瘤作用;ELISA法检测诱导的CTL上清中IFN-γ的水平。结果:CEA mRNA转染后DCs细胞内CEA蛋白显著高于对照组(83.32%vs3.34%,P<0.01)。CEA mRNA转染组DCs在效靶比为1∶10时,刺激T细胞增殖作用最强,明显高于未转染组[(19.11±1.89)%vs(15.59±0.70)%,P<0.05]。CEAmRNA转染组DCs能产生CEA特异性的CTL效应,在效靶比为5∶1、10∶1、20∶1和40∶1时杀伤率分别为[(5.42±0.87)%、(14.09±1.13)%、(27.16±0.72)%、(32.49±0.84)%,P<0.01],而未转染组和对照靶细胞均无杀伤作用。转染组DCs诱导的CTL上清中IFN-γ分泌量显著高于未转染组[(141.73±28.61)vs(9.45±4.63)pg/ml,P<0.01]。结论:CEAmRNA转染的成熟DCs体外能产生特异性抗肿瘤作用,为研制CEA RNA-DCs疫苗提供了实验依据。     

重组腺病毒介导survivin基因转染树突状细胞对肾细胞癌的免疫效应

目的:研究重组腺病毒介导survivin基因转染的树突状细胞(DCs)体外诱导特异性抗肾细胞癌的免疫效应.方法:以携带survivin基因的重组腺病毒(Ad-svv)感染DCs, Western bloting检测转染DCs的survivin的表达,流式细胞术检测DCs表面分子CD83、MHCⅡ、CD80、CD86的表达,ELISA法检测DCs培养上清中IL-12 的含量;混合淋巴细胞反应(MLR)测定DCs刺激同种异体淋巴细胞增殖的能力, ELISA法检测DCs刺激淋巴细胞后上清中IFN-γ含量,MTT法检测其诱导的特异的细胞毒性T淋巴细胞(CTLs)免疫效应.结果:各组Ad-svv转染DCs后均表现出成熟的DCs表型特征,均可见survivin蛋白表达;转染Ad-svv或转染空白腺病毒载体(Ad-CMV)的DCs上清中IL-12均高于对照组(P<0.01),转染Ad-svv的DCs上清中IL-12高于转染Ad-CMV-DCs组(P<0.01).MLR中,转染或未转染腺病毒的DCs均能刺激同种异体T淋巴细胞的增殖,Ad-svv-DC刺激T淋巴细胞增殖的能力最强(P<0.01);MLR后,转染或未转染重组腺病毒的DCs均能刺激T淋巴细胞IFN-γ的分泌,Ad-svv-DC组IFN-γ的分泌能力最强(P<0.01).Ad-svv-DCs组诱导的CTL对survivin表达阳性的786-0肾癌细胞的杀伤率明显高于无survivin表达的L-02肝细胞(P<0.01),Ad-CMV-DCs、空白DC对786-0肾癌细胞无杀伤作用.结论:重组腺病毒介导survivin基因转染能显著提高DCs对肾癌细胞抗原的提呈能力、激活特异性细胞毒性T淋巴细胞、诱导针对survivin的特异性抗癌免疫效应.     

CEA多聚核苷酸疫苗免疫原性的实验研究

以CEA为靶抗原的基因免疫治疗是近年来肿瘤治疗学研究的突出进展,我们用CEA真核表达质粒(pCEA)免疫兔子,分别以重组人CEA痘苗病毒(rV-CEA)和生理盐水作阳性和阴性对照.与生理盐水组相比,pCEA组和rV-CEA组兔血清CEA含量明显升高,并出现高滴度的抗人CEA抗体,CEA核苷酸疫苗较rV-CEA疫苗作用时间持续更长久.     

人肺癌组织总RNA转染树突状细胞方法的优化

背景与目的树突状细胞(dendriticcell,DCs)作为体内惟一能活化初始T细胞的抗原递呈细胞,是激发机体特异性免疫反应的关键,以DCs为基础构建的疫苗广泛应用于各种肿瘤免疫治疗中。其中RNA转染DCs构建DCs疫苗的方法,因避免了抗原的筛选和鉴定,所需肿瘤量小等优点,特别适于像肺癌这样的缺乏特异性肿瘤抗原、异质性大、抗原性弱的肿瘤。然而,目前缺乏RNA转染DCs的最佳时间和方法的研究。本研究以人肺癌组织总RNA体外转染DCs,试图摸索转染DCs的最佳条件。方法用免疫组化的方法选择肿瘤组织癌胚抗原CEA、粘蛋白MUC1双阳性的10例肺癌患者,一步法提取肿瘤组织总RNA,采集和分离外周血单核细胞,体外培养DCs和T细胞,将RNA于不同时间和不同方法转染DCs,用流式细胞仪检测CEA和MUC1的表达,混合淋巴细胞反应测定DCs刺激自体T细胞增殖能力。结果未成熟期DCs转染人肺癌总RNA后CEA和MUC1表达量(11.33±2.64和39.68±7.25)明显高于成熟期DCs(5.46±1.63和27.17±4.16),且刺激自身T细胞增殖反应能力更强。电穿孔法转染人肺癌总RNA后DCs表达CEA和MUC1的量(20.53±3.64和65.39±9.33)明显多于脂质体转染(11.33±2.64和39.68±7.25)和直接混合法(0.91±0.27和18.53±3.26),且刺激自身T细胞增殖反应能力更强。结论采用电穿孔法将肺癌总RNA体外转染未成熟DCs可以使DCs表达肿瘤抗原量更高,刺激T细胞增殖的活性更强。     

人MeCP2基因shRNA真核表达质粒的构建及鉴定

目的 构建针对人甲基化结合蛋白MeCP2的shRNA真核表达质粒,稳定转染肺腺癌细胞A-549观察其对MeCP2表达的影响.方法 根据MeCP2的mRNA序列,利用Ambion网上设计软件设计两条针对该基因不同靶点的shRNA干扰序列,克隆到线性化的质粒载体上,PCR、测序鉴定插入成功,且插入方向正确.转染A-549细胞,观察其在mRNA和蛋白水平对MeCP2的影响.结果 成功构建两个MeCP2的shRNA真核表达质粒,并稳定转染到肺癌细胞A-549中,两个真核表达质粒在mRNA水平和蛋白水平对MeCP2有明显的抑制作用.结论 人MeCP2的shRNA真核表达质粒成功构建及鉴定为进一步研究该蛋白的功能奠定了基础.     

人肺癌组织总RNA转染树突状细胞诱导特异性抗肿瘤免疫的研究

目的:探讨以人肺癌组织总RNA体外转染树突状细胞(dendritic cells,DCs)诱导细胞毒T淋巴细胞(cytotoxic T lymptocyte,CTL)发挥特异性抗肿瘤免疫的作用.方法:10例肿瘤组织经免疫组化测定为CEA、MUC1双阳性.一步法提取肿瘤组织总RNA和10例正常肺组织RNA.采集患者外周血单个核细胞体外诱导未成熟DCs,电穿孔法转染肿瘤和肺组织RNA,刺激DCs成熟后,部分行流式细胞仪检测,部分用于体外诱导CTL.以原代培养的肿瘤细胞和肺上皮细胞作为靶细胞,定量乳酸脱氢酶法测定杀伤率.结果:体外培养的DCs形态典型,高表达CD86、CD80、CD40、HLA-DR和CD83.转染肿瘤组织RNA DCs的CEA和MUC1表达量为(20.53±3.64)%和(65.39±9.33)%,明显高于转染肺组织RNA的DCs[(0.78±0.39)%和(18.32±4.24)%],P＜0.01.肿瘤组织RNA转染DCs诱导的CTL可产生针对肿瘤细胞的特异性杀伤;且用自身肿瘤组织RNA转染DCs诱导的CTL对自身肿瘤细胞杀伤活性最大.结论: 以人肺癌总RNA体外转染DCs诱导CTL可以产生特异性抗肿瘤免疫,此方法构建肺癌疫苗是可行的.     

CEA分泌性肿瘤基因疫苗的研究

以CEA为靶抗原的基因免疫治疗是近年来肿瘤治疗学研究的突出进展,我们用CEA阳性中国胃癌细胞株构建了胃癌cDNA定向表达基因文库,库容量为1.2×10~6,重组率>99%.从文库随机挑出10个噬菌斑,对其插入片段做PCR扩增,电泳显示插入片段大小介于0.5～5Kb,平均1±500pb,符合一般cDAN文库构建的要求,为今后克隆已知或未知目的基因创造了条件.用国外获得的人CEA真核表达质粒,构建了中国天坛株重组人CEA痘苗病毒(rV-CEA),经细胞学和兔动物接种实验再次证实:中国天坛株痘苗病毒也是一种高效真核表达载体;rV-CEA在活体可高效表达人CEA,可激发机体抗CEA的免疫反应;rV-CEA的应用是安全的.用CEA真核表达质粒(pCEA)免疫兔子,兔血清CEA含量升高,     

人核糖体蛋白L6对白血病K562/A02细胞耐药性的影响

目的观察核糖体蛋白L6(RPL6)表达的改变对白血病耐药性的作用。方法通过RT-PCR方法获得RPL6cDNA序列,用真核表达载体pcDNA3.1( )分别构建正向插入和反向插入的RPL6cDNA重组质粒。以脂质体将正义RPL6cDNA真核表达质粒转染K562细胞,将反义RPL6cDNA真核表达质粒转染K562/A02细胞,以MTT观察其对化疗药物耐药性的作用。结果转染正义RPL6cDNA真核表达质粒后,K562细胞对阿霉素的耐药性比未转染的K562细胞增强3.25倍,转染反义RPL6cDNA真核表达质粒后,K562/A02细胞对阿霉素的耐药性比未转染的K562/A02细胞降低62%。结论RPL6基因过表达在K562/A02细胞耐药性的形成中起重要作用。     

GPC3基因转染的树突状细胞对人肝癌HepG2细胞杀伤作用的观察

目的:以GPC3基因转染人外周血单个核细胞来源的树突状细胞(DCs),诱导CTL产生特异性抗肝癌免疫.方法:从HLA-A2正常健康成人外周血分离单个核细胞,经GM-CSF和IL-4诱导产生DCs;通过脂质体转染法将携带人GPC3基因的质粒pEF-hGPC3转染DCs,蛋白质印迹法检测磷脂酰肌醇蛋白聚糖-3表达,流式细胞仪检测DCs表型的变化;MTT法检测DC诱导CTL对人肝癌细胞HepG2的特异性杀伤.结果:经细胞因子诱导产生了具有典型形态学的DCs,经肿瘤坏死因子-α(TNF-α)刺激成熟后可高表达CD80、CD86及CD83,而转染GPC3基因对协同刺激因子在DCs中的表达的影响并不显著.转染GPC3基因后,DCs可促进CTL特异性杀伤HepG2细胞,在不同效靶比的杀伤率:100∶1为(38.90±0.95)%,50∶1为(30.83±1.24)%,10∶1为(20.84±0.65)%,明显高于空载体组和对照组,P＜0.05.结论:GPC3基因转染人外周血单个核细胞来源的DCs可诱导和促进CTL特异性杀伤肝癌细胞HepG2作用,为治疗肝癌提供了新的免疫靶点.     

The infection of human dendritic cells with recombinant avipox vectors expressing a costimulatory molecule transgene (CD80) to enhance the activation of antigen-specific cytolytic T cells

Human dendritic cells (DCs) express MHC class I and II molecules and several T-cell costimulatory molecules that contribute to their efficiency as antigen-presenting cells (APCs). Whereas most human DC populations uniformly express some costimulatory molecules such as B7-2 (CD86), previous studies have shown a wide variation in the expression of B7-1 (CD80) among different human DC preparations. In the studies reported here, we demonstrate that replication-defective avipox vectors expressing B7-1 can be used to rapidly and efficiently infect human DCs and can enhance the efficacy of human DCs to activate specific human T-cell populations. This has been demonstrated both in systems using peptide as a source of signal 1 and in systems using recombinant avipox vector to deliver signal 1. The antigen used in these studies was the tumor-associated human carcinoembryonic antigen (CEA). An immunodominant 9-mer CTL epitope for CEA (designated CAP-1) has been previously characterized (K. Y. Tsang et al., J. Natl. Cancer Inst. (Bethesda), 87: 982-990, 1995). The source of signal 1 used in these studies was (a) the CAP-1 peptide; (b) recombinant avipox-CEA; or (c) the dual transgene recombinant avipox-CEA/B7-1. These studies demonstrate that CEA-specific T cells are more efficiently activated using as APCs peptide-pulsed DCs infected with avipox-B7-1, as compared with peptide-pulsed DCs infected with wild-type vector, or with uninfected peptide-pulsed DCs. Greater activation of CEA-specific T cells was also obtained using as APCs DCs that were infected with avipox-CEA/B7-1 as compared with the use of DCs infected with avipox-CEA. A CEA tetramer was also used to isolate high- and low-tetramer-binding CEA-specific T-cell populations. Although both high- and low-tetramer-binding T cells had the ability to lyse CEA peptide-pulsed targets, only the high-tetramer-binding T cells had the ability to lyse colon carcinoma cells expressing CEA, which suggests the existence of tetramer-binding populations with different T-cell receptor (TCR) affinities. The demonstrated safety of recombinant avipox vectors in humans and the previously demonstrated ability to administer them multiple times without host immune response limitations indicate that these vectors expressing B7-1 have a potential use in enhancing the efficacy of human DC immunotherapy protocols using either peptide or recombinant vector to deliver signal 1.     

Induction of carcinoembryonic antigen (CEA)-specific cytotoxic T-lymphocyte responses in vitro using autologous dendritic cells loaded with CEA peptide or CEA RNA in patients with metastatic malignancies expressing CEA.

The application of dendritic cells (DC) to the active immunotherapy of cancer currently relies on the generation of potent DC capable of presenting tumor antigens such as carcinoembryonic antigen (CEA). It is unknown whether the T cells of patients with advanced malignancies can be reliably stimulated against tumor antigens by their autologous DC. In this study, starting with the peripheral blood mononuclear cells (PBMC) of patients with metastatic malignancies expressing CEA, autologous DCs were generated in vitro in serum-free media supplemented with GM-CSF and IL-4. The DCs from HLA A2 positive patients were loaded with the CEA peptide CAP-1 and the DCs from HLA A2 negative patients were depleted of bystander lymphocytes and loaded with mRNA encoding CEA. The DC preparations were tested to determine their phenotype and were used to stimulate autologous PBMC twice, separated by 10-14 days. The stimulated cells were then tested for their ability to lyse CEA-expressing target cells. We successfully generated an adequate number of DC for a clinical trial from all patients. The harvested DC preparations contained 49% DC and 87% DC if depleted of bystander lymphocytes. Phenotypic analysis showed the typical pattern of CD11c+ CD40+ CD86+ HLA-DR+ CD80(low) CD83(low) CD14(low). All preparations but one were able to stimulate CEA-specific cytotoxic T-lymphocyte (CTL) activity, suggesting that the majority of patients are not anergic to CEA and possess functional DC. The CTL activity was similar for the CEA peptide and CEA RNA-loaded DC.     

抗CEA抗体可变区基因的克隆及其嵌合抗体的表达

目的 在真核细胞中表达抗癌胚抗原（carcinoembryonic antigen,CEA)人－鼠嵌合抗体。方法 从分泌抗CEA鼠单抗C50的杂交瘤细胞扩增、克隆可变区基因。测序鉴定后连入真核表达载体,导入二氢叶酸还原酶缺陷型中国仓鼠卵巢（dihydrofolate reductase-deficient Chinese hamster ovary CHO-dhfr）细胞进行表达。采用间接和竞争抑制ELISA检测表达产物的人源性和抗原结合特异性。结果 序列测定初步确定所克隆的是功能性抗体可变区基因。在转染细胞上清中测到抗CEA嵌合抗体的表达。ELISA试验证实嵌合抗体具有人的恒定区,并与原鼠单抗C50有相同的抗原结合特异性。结论 成功地在真核细胞中表达了抗CEA人－鼠嵌合抗体。     

A Phase I study of active immunotherapy with carcinoembryonic antigen peptide (CAP-1)-pulsed, autologous human cultured dendritic cells in patients with metastatic malignancies expressing carcinoembryonic antigen.

Dendritic cells (DCs), antigen-presenting cells capable of priming naive T cells to specific antigens in an HLA-restricted fashion, have been demonstrated to induce protective T cell-mediated immunity in tumor-bearing animals. We performed this study to test the safety, feasibility, and clinical response of immunizations with in vitro-generated DCs, loaded with an HLA-A2-restricted peptide fragment of the tumor antigen carcinoembryonic antigen (CEA), for the treatment of patients with advanced CEA-expressing malignancies. Cell preparations enriched for autologous DCs were generated from the patients' plastic adherent peripheral blood mononuclear cells in serum-free media supplemented with granulocyte macrophage colony-stimulating factor and interleukin-4. Within the cell preparation, 66% of the cells expressed the phenotype typical for DCs (CD86high, HLA-DRhigh, and CD14low). The DCs were loaded with the CEA peptide CAP-1 and cryopreserved. Groups of three to six patients received four weekly or biweekly i.v. infusions of the CAP-1-loaded DC in escalating dose levels of 1 x 10(7), 3 x 10(7), and 1 x 10(8) cells/dose. A subset of the patients in the last group also received intradermal injections of 1 x 10(6) DCs. There were no toxicities directly referable to the treatments. One patient had a minor response, and one had stable disease. Skin punch biopsy at DC injection sites demonstrated pleomorphic infiltrates in the three patients evaluated. We conclude that it is feasible and safe to generate and administer large numbers of previously cryopreserved DCs loaded with CAP-1 peptide to patients with advanced malignancies.     

Analyses of recombinant vaccinia and fowlpox vaccine vectors expressing transgenes for two human tumor antigens and three human costimulatory molecules.

PURPOSE: The poor immunogenicity of tumor antigens and the antigenic heterogeneity of tumors call for vaccine strategies to enhance T-cell responses to multiple antigens. Two antigens expressed noncoordinately on most human carcinomas are carcinoembryonic antigen (CEA) and MUC-1. We report here the construction and characterization of two viral vector vaccines to address these issues. EXPERIMENTAL DESIGN: The two viral vectors analyzed are the replication-competent recombinant vaccinia virus (rV-) and the avipox vector, fowlpox (rF-), which is replication incompetent in mammalian cells. Each vector encodes the transgenes for three human costimulatory molecules (B7-1, ICAM-1, and LFA-3, designated TRICOM) and the CEA and MUC-1 transgenes (which also contain agonist epitopes). The vectors are designated rV-CEA/MUC/TRICOM and rF-CEA/MUC/TRICOM. RESULTS: Each of the vectors is shown to be capable of faithfully expressing all five transgenes in human dendritic cells (DC). DCs infected with either vector are shown to activate both CEA- and MUC-1-specific T-cell lines to the same level as DCs infected with CEA-TRICOM or MUC-1-TRICOM vectors. Thus, no evidence of antigenic competition between CEA and MUC-1 was observed. Human DCs infected with rV-CEA/MUC/TRICOM or rF-CEA/MUC/TRICOM are also shown to be capable of generating both MUC-1- and CEA-specific T-cell lines; these T-cell lines are in turn shown to be capable of lysing targets pulsed with MUC-1 or CEA peptides as well as human tumor cells endogenously expressing MUC-1 and/or CEA. CONCLUSION: These studies provide the rationale for the clinical evaluation of these multigene vectors in patients with a range of carcinomas expressing MUC-1 and/or CEA.     

Effect of radiation on the expression of carcinoembryonic antigen of human gastric adenocarcinoma cells

The changes of antigenic expression of cultured human gastric adenocarcinoma MKN45 cells caused by irradiation were investigated to elucidate the immune responses to localized irradiation. The expression of carcinoembryonic antigen (CEA) showed remarkable increases in the culture supernatant and on the surface of the membrane of irradiated cells. The expression of major histocompatibility complex Class I antigen on the membrane also was enhanced by irradiation. In addition, the irradiated cell groups, when analyzed using a CEA-specific probe, showed remarkable increases in the CEA mRNA. These enhancements increased in the 10-Gy and 15-Gy irradiated populations compared with the 5-Gy irradiated population. These results suggest that the enhancement of expression of CEA by radiation takes place at the CEA gene expression (mRNA) level but not at the protein level.     

Effective production of carcinoembryonic antigen by conversion of the membrane-bound into a recombinant secretory protein by site-specific mutagenesis

Carcinoembryonic antigen (CEA), the most widely used human tumor marker, is a heavily glycosylated protein over-expressed by a wide range of tumors. It has been indicated that CEA might be a useful target for human anti-tumor immunotherapy. CEA assay for research as well as clinical trials demands a continuous source of CEA protein preparations. In a multi-purpose research program to provide a reliable source for large production of CEA, we converted the membrane-bound carcinoembryonic antigen into a secretory protein by site-specific mutagenesis. We made the secretory CEA protein by introducing a new stop codon at 99 bp upstream of the original stop codon in CEA cDNA by PCR-based mutagenesis. The glycosylation of recombinant CEA proteins, especially those destined for administration to human trials is crucially important. To produce CEA with the same glycosylation pattern and immunogenicity as the native CEA expressed by human tumorsin vivo, the truncated CEA cDNA which does not encode the last C-terminal 33-amino acid hydrophobic domain was transfected into HT29, a human colon carcinoma cell line by the calcium phosphate method. Stable transfectants were selected and pooled. CEA secretion from the cells was verified by analysis of the transfectant culture supernatant for CEA protein. As determined by ELISA, 16 μg/L of recombinant CEA was secreted per 10⁶ transfectants within 48 hrs, an increase over 40 times relative to the untransfected cells. The size of the recombinant CEA secreted by HT29 transfectants in our experiment is identical to that of reference CEA secreted from tumors and is fully antigenic. It seems that the C-terminal truncation does not affect CEA glycosylation in HT29 cells. It is predicted that human cancer immunotherapy using recombinant CEA expressed in this system would be more effective than the commercial protein which is usually prepared from bacterial or other heterologous expression systems.     

Antitumor Activity of Lentivirus-mediated Interleukin -12 Gene Modified Dendritic Cells in Human Lung Cancer in Vitro

Objectives: Dendritic cell (DC)-based tumor immunotherapy needs an immunogenic tumor associatedantigen (TAA) and an effective approach for its presentation to lymphocytes. In this study we explored whethertransduction of DCs with lentiviruses (LVs) expressing the human interleukin-12 gene could stimulate antigenspecificcytotoxic T cells (CTLs) against human lung cancer cells in vitro. Methods: Peripheral blood monocytederivedDCs were transduced with a lentiviral vector encoding human IL-12 gene (LV-12). The anticipated targetof the human IL-12 gene was detected by RT-PCR. The concentration of IL-12 in the culture supernatant of DCswas measured by ELISA.Transduction efficiencies and CD83 phenotypes of DCs were assessed by flow cytometry.DCs were pulsed with tumor antigen of lung cancer cells (DC+Ag) and transduced with LV-12 (DC-LV-12+Ag).Stimulation of T lymphocyte proliferation by DCs and activation of cytotoxic T-lymphocytes (CTL) stimulatedby LV-12 transduced DCs pulsed with tumor antigen against A549 lung cancer cells were assessed with methylthiazolyltetrazolium (MTT). Results: A recombinant lentivirus expressing the IL-12 gene was successfullyconstructed. DC transduced with LV-12 produced higher levels of IL-12 and expressed higher levels of CD83than non-transduced. The DC modified by interleukin -12 gene and pulsed with tumor antigen demonstratedgood stimulation of lymphocyte proliferation, induction of antigen-specific cytotoxic T lymphocytes and antitumoreffects. Conclusions: Dendritic cells transduced with a lentivirus-mediated interleukin-12 gene have anenhanced ability to kill lung cancer cells through promoting T lymphocyte proliferation and cytotoxicity.     

Immunotherapy with autologous,human dendritic cells transfected with carcinoembryonic antigen mRNA

Immunizations with dendritic cells (DC) transfected with RNA encoding tumor antigens induce potent tumor antigen-specific immune responses in vitro and in murine models. We performed a phase I study of patients with advanced carcinoembryonic antigen (CEA)-expressing malignancies followed by a phase II study of patients with resected hepatic metastases of colon cancer to assess safety and feasibility of administering autologous DC loaded with CEA mRNA. The immunizations were well tolerated. Of the 24 evaluable patients in the dose-escalation phase, there was 1 complete response (by tumor marker), 2 minor responses, 3 with stable disease, and 18 with progressive disease. In the phase II study, 9 of 13 patients have relapsed at a median of 122 days. Evidence of an immunologic response was demonstrated in biopsies of DC injection sites and peripheral blood of selected patients. We conclude that it is feasible and safe to administer mRNA-loaded DC to patients with advanced malignancies.     

Tumor cyclooxygenase 2-dependent suppression of dendritic cell function.

Dendritic cells (DCs) serve as professional antigen-presenting cells and are pivotal in the host immune response to tumor antigens. To define the pathways limiting DC function in the tumor microenvironment, we assessed the impact of tumor cyclooxygenase (COX)-2 expression on DC activities. Bone marrow-derived DCs were cultured in either tumor supernatant (TSN) or TSN from COX-2-inhibited tumors. After culture, DCs were pulsed with tumor-specific peptides, and their ability to generate antitumor immune responses was assessed following injection into established murine lung cancer. In vitro, DC phenotype, alloreactivity, antigen processing and presentation, and interleukin (IL)-10 and IL-12 secretion were evaluated. DCs cultured in TSN failed to generate antitumor immune responses and caused immunosuppressive effects that correlated with enhanced tumor growth. However, genetic or pharmacological inhibition of tumor COX-2 expression restored DC function and effective antitumor immune responses. Functional analyses indicated that TSN causes a decrement in DC capacity to (a) process and present antigens, (b) induce alloreactivity, and (c) secrete IL-12. Whereas TSN DCs showed a significant reduction in cell surface expression of CD11c, DEC-205, MHC class I antigen, MHC class II antigen, CD80, and CD86 as well as a reduction in the transporter-associated proteins, transporter associated with antigen processing 1 and 2, the changes in phenotype and function were not evident when DCs were cultured in supernatant from COX-2-inhibited tumors. We conclude that inhibition of tumor COX-2 expression or activity can prevent tumor-induced suppression of DC activities.