RPL8基因修饰的树突状细胞对胶质瘤的免疫治疗作用

目的 探讨RPL8基因修饰的树突状细胞（DC）对胶质瘤生长的抑制作用。方法 通过重组腺病毒将RPL8基因导入树突状细胞,荧光显微镜观察细胞内绿色荧光蛋白的表达,RT-PCR分析细胞内RPL8mRNA表达,RPL8基因修饰的DC与T细胞混合培养,MTT法检测活化T细胞对胶质瘤细胞的杀伤效应。DC注入荷瘤小鼠体内,观察肿瘤体积变化及小鼠生存时间。结果 重组病毒转染DC后,细胞内可见绿色荧光,RT-PCR分析细胞内有RPL8mRNA表达;Ad-RPL8组、Ad组及PBS组激活T细胞对GL261细胞的杀伤率分别为78%、49%和43%,Ad-RPL8组较Ad组及PBS组明显增高（P<0.05）,RPL8基因修饰的DC注入小鼠后,与Ad组及PBS组比,小鼠生存期明显延长（P<0.05）,肿瘤体积变小（P<0.05）,肿瘤细胞坏死增多。结论 RPL8基因修饰的DC对胶质瘤具有生长抑制作用,为胶质瘤免疫治疗开辟新途径。     

淋巴细胞减少期联合免疫重建和瘤苗免疫增强抗肿瘤免疫的机制

目的阐明向免疫重建的淋巴细胞减少小鼠（reconstituted lymphopeniemice,RLM）进行瘤苗免疫增强抗肿瘤免疫反应的机制。方法分别以放疗和环磷酰胺处理C57BL／6小鼠,建立淋巴细胞减少模型,并各设正常一非免疫组、RLM-非免疫组、正常-免疫组和RLM-免疫组等4个实验组。在免疫重建的24h内,分别用灭活黑色素瘤细胞F10（放疗实验部分）和GM—CSF修饰的活黑色素瘤细胞D5-G6（化疗实验部分）免疫,8—10d后采集肿瘤疫苗部位引流淋巴结（tumor vaccine draining lymphnode,TVDLN）,以FACS分析细胞表型。磁珠纯化的T细胞分别经anti—CD3及anti—TCRβ刺激后,分别以[^3H]一TdR掺入法和FACS检测T细胞的增殖能力和CD69的表达情况,以此反映T细胞的激活阈值。结果RLM-免疫组TVDLN中,DC细胞和活化T细胞的频数显著增高。新鲜T细胞的体外增殖能力显著增强,激活阈值明显降低。结论放、化疗引起的淋巴细胞减少可诱导T细胞增殖活化,激活阈值降低,有助于瘤苗免疫打破机体对肿瘤的免疫耐受,增强抗肿瘤免疫反应。     

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。     

自体恶性黑色素瘤抗原激活的树突状细胞体外诱导免疫试验

树突状细胞(dendritic cells,DC)是迄今为止所知的抗原呈递能力最强的抗原呈递细胞(antigen presenting cells,APC).肿瘤患者因DC免疫功能低下致宿主抗肿瘤免疫无能.研究表明,人外周血单核细胞在体外用粒/巨噬细胞集落刺激因子(granulocyte/macrophage colony-stimulating factor,GM-CSF)及白介素4(IL-4)诱导后,可培养出表达高水平MHCI、MHCII类抗原和CD80、CD86等因子的DC.本实验拟应用黑色素瘤患者外周血单核细胞,经GM-CSF及IL-4诱导后获得DC,再经自体肿瘤细胞冻融物冲击,在体外激活自体T淋巴细胞产生细胞毒性T淋巴细胞(CTL),观察其体外抗肿瘤作用.     

放疗或化疗诱导淋巴细胞减少联合免疫重建和瘤苗免疫

目的利用淋巴细胞减少期T细胞发生增殖活化的原理,以全身照射或环磷酰胺引起淋巴细胞减少,联合免疫重建及肿瘤疫苗免疫,以增强机体的肿瘤特异性免疫反应。方法分别以放疗或化疗（环磷酰胺）引起小鼠淋巴细胞减少,然后输入同系小鼠的未致敏脾细胞,建立免疫重建的淋巴细胞减少小鼠模型（RLM）。用黑色素瘤细胞F10对前者行免疫．肿瘤攻击实验,并行T细胞亚群清除试验。而化疗-RLM-免疫模型的抗肿瘤免疫反应效果通过过继免疫治疗检测。免疫用瘤苗为GMCSF修饰的黑色素瘤细胞D6-G6。免疫后9～10d,采集肿瘤疫苗接种部位的引流淋巴结,制备效应T细胞,然后过继回输给荷瘤3d（D5）的小鼠。2周后处死小鼠,计数肺转移灶数目。结果63．2％的放疗-RLM-免疫组小鼠可对肿瘤攻击产生抵抗,显著高于正常-免疫组（16．7％,P〈0．0001）。CD8^＋T细胞是介导抗肿瘤保护性免疫的主要效应细胞。延长免疫重建和瘤苗接种之问的间隔可削弱保护性抗肿瘤免疫。化疗-RLM-免疫组效应T细胞的在体抗肿瘤活性显著强于正常．免疫组。结论在放、化疗引起的淋巴细胞减少期进行瘤苗免疫,有助于打破机体对肿瘤的免疫耐受,增强抗肿瘤免疫反应。     

血管内皮生长因子受体-2胞外区基因修饰树突状细胞的抗实验性肺转移作用

目的研究血管内皮生长因子受体-2胞外区基因修饰树突状细胞(DC)的抗肿瘤转移作用及其机制。方法电穿孔法基因转染DC,ELISA检测基因转染DC表达sVEGFR-2水平;经尾静脉给C57BL／6小鼠分别注射PBS、DC、pcDNA3．1修饰的DC(DC-vector)、pcDNA3．1／sVEGFR-2修饰的DC(DC-sVEGFR-2),连续3次,每次间隔1周,最后一次免疫注射后10 d,以51Cr释放法检测小鼠脾细胞VEGFR-2特异性CTL活性,藻酸钠小珠法检测肿瘤细胞诱导的新生血管形成,以B16黑色素瘤肺转移模型观察DC-sVEGFR-2免疫的抗肿瘤转移作用。以抗-CD4单抗或抗-CD8单抗分别剔除体内CD4+T细胞及CD8+T细胞,研究DC-sVEGFR-2免疫抗肿瘤转移作用的免疫学机制。结果DC- sVEGFR-2能有效表达sVEGFR-2,而DC-vector和DC不表达sVEGFR-2。DC-sVEGFR-2免疫小鼠脾细胞能有效杀伤VEGFR-2+的靶细胞H5V和3LL-sVEGFR,与对照组相比,差异有统计学意义(P<0．01),但对VEGFR-2-的同系EL4和3LL细胞无杀伤作用。DC-sVEGFR-2免疫能显著抑制肿瘤诱导的新生血管形成,DC-sVEGFR-2免疫小鼠藻酸钠小珠中FITC-dextran的摄取量仅为对照组的50％,与对照组相比,差异有统计学意义(P<0．01)。DC-sVEGFR-2免疫组小鼠B16黑色素瘤肺转移灶数目显著减少,瘤灶体积显著小于对照组,与DC-vector免疫组相比,肺表面转移灶数目下降81．9％(49．7±12．7:9．0±3．2,P<0．01)。体内T细胞亚群剔除试验显示,DC-sVEGFR-2免疫的抗肿瘤转移作用由CD8+T细胞介导。结论DC-sVEGFR-2免疫能打破自身免疫耐受,诱导针对VEGFR-2的CTL应答,抑制肿瘤诱导的新生血管形成,显著抑制肿瘤的转移,其抗肿瘤转移作用由CD8+T细胞介导。     

HSP70-Id复合物修饰的树突状细胞体外诱导特异性抗肿瘤作用

目的观察人慢性B淋巴细胞性白血病（B-CLL）细胞的独特型抗原Id-ScFv与热休克蛋白70（HSP70）形成复合物修饰的树突状细胞（DC）体外诱导特异性抗肿瘤作用,并初步探讨其机制。方法将HSP70与Id-ScFv体外结合形成复合物HSP70-Id,修饰自人外周血单核细胞获取的DC。倒置相差显微镜观察DC的形态特征;流式细胞仪检测修饰前后DC的表型变化,酶联免疫吸咐试验（ELISA）检测DC分泌的白细胞介素12（IL-12）和肿瘤坏死因子-α（TNF-α）,四甲基偶氮唑蓝（MTT）法检测修饰的DC对自身淋巴细胞的激活和增殖作用,流式细胞仪检测激活的自身淋巴细胞T细胞亚群的变化,台盼蓝染色法检测其对Daudi、K562和HepG2等细胞的杀伤作用。结果DC体外诱导培养成功,HSP70-Id复合物可使DC成熟,镜下可见典型的DC形态,其CD1a表达率为20％-30％,CD83表达率〉72％,CD86和HLA-DR表达显著增加（P〈0．05）,上清中IL-12、TNF-α亦显著高于DC对照组（P〈0．01）。HSP70-Id复合物修饰的DC激活自身淋巴细胞,对Daudi细胞的杀伤率为71．24％,而对K562细胞杀伤作用较弱,对HepG2细胞无明显作用。其淋巴细胞亚群中,CD4^＋T细胞、CD8^＋T细胞的比例均显著增加,分别为56．51％和70．21％,CD4^＋T细胞／CD8^＋T细胞比值由空白对照组的1．49倒置为0．81。结论HSP70-Id复合物修饰的DC生物学活性增强,经其刺激后,传代培养的淋巴细胞可产生高效而特异性的抗肿瘤免疫效应,可能是CD4^＋T细胞、CD8^＋T细胞及DC协同作用的结果。     

肿瘤细胞裂解物联合IL-2预防黑色素瘤发生并抑制肿瘤生长的免疫机制

目的 探讨肿瘤细胞裂解物（TCL）联合IL-2对黑色素瘤的预防和抑制作用及其免疫机制。方法 超声破碎仪制备B16F10黑色素瘤细胞TCL。24只C57BL/6小鼠随机分为四组,分别予PBS、IL-2、TCL及TCL+IL-2预防性免疫3周,第4周对侧植瘤。观察小鼠出瘤时间及肿瘤大小,连续采集外周血行流式细胞术动态监测CD4+T及CD8+T细胞。流式细胞术及免疫组织化学检测小鼠脾脏及肿瘤组织CD4+T及CD8+T细胞。结果 TCL+IL-2组预防性免疫后明显延迟了小鼠的出瘤时间（P=0.034）,且肿瘤体积（P=0.023）及瘤重（P=0.0015）也明显小于对照组。流式细胞术动态监测结果提示TCL+IL-2组及单纯TCL组外周血中CD8+T细胞较对照组均有明显上升（P=0.0016, P=0.012）。TCL+IL-2组的CD4+T细胞在植瘤后较对照组有所下降（P=0.0089）。脾脏及肿瘤组织中CD4+T细胞及CD8+T细胞的结果与外周血中的表达趋势相同。结论 TCL联合IL-2的肿瘤疫苗通过激活CD8+T细胞途径,预防小鼠黑色素瘤的发生并抑制肿瘤生长。     

表皮生长因子受体通路底物8疫苗对乳腺癌细胞的抑制效应及其可能机制

目的：探索表皮生长因子受体通路底物8（epidermal growth factor receptor substrate 8,EPS8）疫苗对乳腺癌细胞的抑制效应及其可能的机制。方法:Western blotting检测EPS8蛋白在小鼠乳腺癌4T1细胞株中的表达。通过基因重组、表达和纯化等技术制备特异性的小鼠源性EPS8,以EPS8蛋白为靶点制备抗肿瘤疫苗并免疫BALB/c小鼠,间接ELISA测定免疫前后不同时间小鼠血清内抗EPS8抗体效价;流式细胞术检测免疫前后的脾T淋巴细胞亚群比例。建立乳腺癌4T1细胞荷瘤小鼠模型并接种EPS8疫苗,接种佐剂作为对照,比较2组荷瘤小鼠的生存期、肿瘤体积、肿瘤重量,计算EPS8疫苗抑瘤率;流式细胞术检测荷瘤小鼠脾T淋巴细胞亚群比例,LDH法检测其细胞毒性T细胞（CTL）杀伤率。结果：EPS8蛋白在乳腺癌4T1细胞株中高表达。成功构建的EPS8蛋白疫苗免疫小鼠后产生抗EPS8抗体,且随着免疫次数的增加,小鼠体内抗EPS8抗体滴度呈上升趋势。乳腺癌4T1细胞接种于经EPS8疫苗或佐剂免疫后的小鼠后,与佐剂对照组相比,EPS8疫苗组小鼠生存期显著升高\[中位生存时间：44(38~50) vs 37 (34~40) d; t=2.477, P=0043\],肿瘤质量显著降低\[（2.21±0.35）vs（331±0.88）g;t=3.574,P=0.009\],EPS8疫苗的抑瘤率为33.23%。EPS8疫苗组小鼠脾CD4+T比例和CD4+/CD8+比值均显著高于佐剂对照组（P<0.001）,EPS8疫苗组CD4+CD25+Treg/CD4+T细胞的比值显著低于佐剂对照组（P<0.001）。效靶比为20〖DK〗∶1时,EPS8疫苗组CTL对靶细胞的杀伤活性即显著高于佐剂对照组\[(19.05±4.41)% vs (13.36±3.10)%;t=2263,P=0.040\] 。结论：EPS8疫苗不仅具有诱导小鼠产生体液免疫应答的功能,还能够降低荷瘤小鼠体内Treg细胞比例,激活机体内T细胞免疫功能;EPS8疫苗可抑制肿瘤的生长、有效延长荷瘤小鼠的生存期。     

表达CD40L基因的卵巢癌细胞诱导树突状细胞成熟及分泌Th1型细胞因子的作用机制

目的 探讨转染CD40L cDNA的卵巢癌细胞株OVHM对树突状细胞(DC)成熟、分化的影响及诱导其分泌细胞因子的机制.方法 采用脂质体转染法将鼠全长CD40L基因转染人小鼠卵巢癌细胞株OVHM中,用G418筛选出表达CD40L基因的抗药性克隆细胞(CD40L-OVHM).应用免疫磁珠分选并纯化小鼠骨髓DC.将DC与转染和未转染CD40L cDNA的OVHM细胞混合培养,流式细胞术检测DC细胞表面人主要组织相容性复合物Ⅰ类分子(MHC-Ⅰ)、Ⅱ类分子(MHC-Ⅱ)、CD80、CD86和CCR7的表达,逆转录聚合酶链反应(RT-PCR)检测共培养细胞中白细胞介素(IL)-12、IL-23、IL-27、IL-18、γ干扰素(IFN-γ)、Mig基因的表达.结果 DC与CD40L-OVHM细胞混合培养后可形成集落,且上调了DC细胞MHC-Ⅰ、MHC-Ⅱ、CD80、CD86、CCR7的共刺激分子和黏附分子的表达.在DC+CD40L-OVHM组可检测到细胞因子IL-12、IL-23、IL-27、IL-18、IFN-γ、Mig基因的表达,而在DC组、DC+OVHM组、CD40L-OVHM组、OVHM组未检测到这些基因的表达.结论 表达CD40L的卵巢癌细胞促进了DC的成熟,诱导了Th1型细胞因子的分泌,这可能是转染CD40L基因的卵巢癌细胞产生抗肿瘤效应的机制之一.     

负载抗原肽的树突状细胞增强腺病毒载体介导hTRP2诱发抗小鼠黑色素瘤免疫

目的探讨人黑色素瘤相关抗原TRP2(hTRP2)MHCⅠ多肽TRP2p180-188 (SVYDFFVWL)修饰小鼠骨髓来源的树突状细胞(DC),增强腺病毒载体介导hTRP2(Ad hTRP2)诱发的抗小鼠黑色素瘤免疫效果。方法Ad hTRP2免疫C57BL／6小鼠,3周后分别用Ad hTRP2或DC／SVYDFFVWL再免疫一次。用体内细胞毒性T淋巴细胞(CTL)杀伤实验和细胞内IFNγ染色(ICS)分析CTL杀伤活性和IFNγ的产生;或给免疫小鼠皮下接种B16．F10细胞,观察荷瘤小鼠的成活情况。结果测定脾脏中6 h CTL杀伤率和产生IFNγ的CD8+T细胞比例,结果分别是:Ad hTRP2(初免)- Ad hTRP2(加强)组为68．40％±5．50％和0．67％±0．16％,DC／SVYDFFVWL(初免)-DC／SVYDFFVWL(加强)组为28．50％±6．40％和0．22％±0．07％,而Ad hTRP2(初免)-DC／SVYDFFVWL(加强)组为98．90％±0．90％和1．05％±0．21％。荷瘤实验显示,小鼠接种1×106 B16．F10细胞后3个月,DC／SVYDFFVWL(初免)-DC／SVYDFFVWL(加强)组小鼠无一成活,Ad hTRP2(初免)-Ad hTRP2(加强)组只有40％的小鼠存活,而Ad hTRP2(初免)-DC／SVYDFFVWL(加强)组小鼠100％存活。结论用DC／SVYDFFVWL加强免疫能显著地增强Ad hTRP2初次免疫的效果,表明Ad hTRP2(初免)-DC／SVYDFFVWL(加强)免疫是一种克服重复应用腺病毒并不能提高抗肿瘤免疫效应的有效方式。     

A comparison of two types of dendritic cell as adjuvants for the induction of melanoma-specific T-cell responses in humans following intranodal injection.

Dendritic cells (DCs) elicit potent anti-tumoral T-cell responses in vitro and in vivo. However, different types of DC have yet to be compared for their capacity to induce anti-tumor responses in vivo at different developmental stages. Herein, we correlated the efficiencies of different types of monocyte-derived DC as vaccines on the resulting anti-tumor immune responses in vivo. Immature and mature DCs were separately pulsed with a peptide derived from tyrosinase, MelanA/MART-1 or MAGE-1 and a recall antigen. Both DC populations were injected every 2 weeks in different lymph nodes of the same patient. Immune responses were monitored before, during and after vaccination. Mature DCs induced increased recall antigen-specific CD4(+) T-cell responses in 7/8 patients, while immature DCs did so in only 3/8. Expansion of peptide-specific IFN-gamma-producing CD8(+) T cells was observed in 5/7 patients vaccinated with mature DCs but in only 1/7 using immature DCs. However, these functional data did not correlate with the tetramer staining. Herein, immature DCs also showed expansion of peptide-specific T cells. In 2/4 patients vaccinated with mature DCs, we observed induction of peptide-specific cytotoxic T cells, as monitored by chromium-release assays, whereas immature DCs failed to induce peptide-specific cytotoxic T cells in the same patients. Instead, FCS-cultured immature DCs induced FCS-specific IgE responses in 1 patient. Our data demonstrate that this novel vaccination protocol is an efficient approach to compare different immunization strategies within the same patient. Thus, our data define FCS-free cultured mature DCs as superior inducers of T-cell responses in melanoma patients.     

腺病毒转染黑色素瘤抗原基因3的树突状细胞疫苗抗胃癌的免疫效应

目的 研究趋化因子巨噬细胞炎症蛋白1α(MIP-1α)动员的树突状细胞(DC),经黑色素瘤抗原基因3(MAGE-3)腺病毒转染后对胃癌细胞的免疫效应.方法 615小鼠尾静脉注射MIP-1α,分选得到B220-CD11c+细胞,加入细胞因子连续培养,检测其细胞表面标志和混合淋巴细胞反应(MLR).收集培养后的B220-CD11c+细胞,加入编码MAGE-3的重组腺病毒进行转染,制备表达肿瘤抗原的DC疫苗,以荷载小鼠前胃癌(MFC)全肿瘤细胞抗原制备的DC疫苗作为阳性对照.采用二苯基溴化四氮唑蓝(MTT)法,榆测活化的T淋巴细胞在体外对MFC细胞的杀伤作用.采用酶联免疫吸附试验(ELISA),检测γ干扰素(INF-γ)的分泌情况.DC疫苗皮下注射MFC荷瘤小鼠,观察小鼠瘤体生长情况和存活时间.结果 MIP-1α注射后,外周血中B220-CD11c+细胞明显升高.新鲜分离的B220-CD11c+细胞在体外经过细胞因子诱导分化后具有典型的DC表面标志,并在MLR中具有极强的刺激T淋巴细胞增殖的能力.腺病毒转染MAGE-3的DC激活的T淋巴细胞表现出对MFC细胞的特异性杀伤作用,产牛高水平的INF-γ[(1460.00±16.82)ps/ml].实验组荷瘤小鼠接受DC疫苗治疗后,肿瘤牛长缓慢,观察至MFC细胞接种后的第27天,其肿瘤体积仅为(3.46±1.12)cm3;实验组小鼠的肿瘤体积与对照组之间的差异有统计学意义(P<0.01).实验组小鼠存活时间明显延长,与对照组之间的差异有统计学意义(P<0.01).结论 注射趋化因子MIP-1α可快速动员并诱导分化为成熟DC.肿瘤抗原基因MAGE-3经腺病毒转染制备的DC疫苗,在体外可以诱导出针对胃癌细胞的特异性杀伤作用,在体内对MFC荷瘤小鼠有明显的免疫治疗作用.     

The Comparison of Biologic Characteristics between Mice Embryonic Stem Cells and Bone Marrow Derived Dendritic Cells

OBJECTIVE This research was to induce dendritic cells (DCs)from mice embryonic stem cells and bone marrow mononuclear cells in vitro, and then compare the biologic characteristics of them.METHODS Embryonic stem cells (ESCs) suspending cultured in petri dishes were induced to generate embryonic bodies (EBs).Fourteen-day well-developed EBs were transferred to histological culture with the same medium and supplemented 25 ng/ml GM-CSF and 25 ng/ml IL-3. In the next 2 weeks, there were numerous immature DCs outgrown. Meantime, mononuclear cells isolated from mice bone marrow were induced to derive dendritic cells by supplementing 25 ng/ml GM-CSF and 25 ng/ml IL-4, and then the morphology, phenotype and function of both dendritic cells from different origins were examined.RESULTS Growing mature through exposure to lipopolysaccharide (LPS), both ESC-DCs and BM-DCs exhibited dramatic veils of cytoplasm and extensive dendrites on their surfaces, highly expressed CD11c, MHC-Ⅱ and CD86 with strong capacity to stimulate primary T cell responses in mixed leukocyte reaction (MLR).CONCLUSION ESC-DC has the same biologic characteristics as BM-DC, and it provides a new, reliable source for the functional research of DC and next produce corresponding anti-tumor vaccine.     

Murine dendritic cells transfected with human GP100 elicit both antigen-specific CD8(+) and CD4(+) T-cell responses and are more effective than DNA vaccines at generating anti-tumor immunity.

Dendritic cells (DCs) are potent inducers of cytotoxic T lymphocytes (CTLs) when pulsed with an antigenic peptide or tumor lysate. In this report, we have used liposome-mediated gene transfer to examine the ability of plasmid DNA encoding the human melanoma-associated antigen gp100 to elicit CD8(+) and CD4(+) T-cell responses. We also compared the efficacy between gp100 gene-modified DCs and naked DNA (pCDNA3/gp100)-based vaccines at inducing anti-tumor immunity. DCs were generated from murine bone marrow and transfected in vitro with plasmid DNA containing the gp100 gene. These gp100-modified DCs (DC/gps) were used to stimulate syngeneic naive spleen T cells in vitro or to immunize mice in vivo. Antigen-specific, MHC-restricted CTLs were generated when DC/gps were used to prime T cells both in vitro and in vivo. Thus, these CTLs were cytolytic for gp100-transfected syngeneic (H-2(b)) tumor MCA106 (MCA/gp) and vaccinia-pMel17/gp100-infected syngeneic B16 and MCA106, but not parental tumor MCA106 and B16, or gp100-transfected allogeneic tumor P815 (H-2(d)). Immunization with DC/gp protected mice from subsequent challenge with MCA/gp but not parental MCA106. Antibody-mediated T-cell subset depletion experiments demonstrate that induction of CTLs in vivo is dependent on both CD4(+) and CD8(+) T cells. Furthermore, DC/gp immunization elicits an antigen-specific CD4(+) T-cell response, suggesting that DC/gps present MHC class II epitopes to CD4(+) T cells. In addition, our data show that gene-modified, DC-based vaccines are more effective than the naked DNA-based vaccines at eliciting anti-tumor immunity in both prophylactic and therapeutic models. These results suggest that the use of DCs transfected with plasmid DNA containing a gene for TAA may be superior to peptide-pulsed DCs and naked DNA-based vaccines for immunotherapy and could provide an alternative strategy for tumor vaccine design.     

Targeting the immunoregulator SRA/CD204 potentiates specific dendritic cell vaccine-induced T-cell response and antitumor immunity

Although dendritic cell (DC) vaccines offer promise as cancer immunotherapy, further improvements are needed to amplify their clinical therapeutic efficacy. The pattern recognition scavenger receptor SRA/CD204 attenuates the ability of DCs to activate CD8(+) T-cell responses. Therefore, we examined the impact of SRA/CD204 on antitumor responses generated by DC vaccines and we also evaluated the feasibility of enhancing DC vaccine potency by SRA/CD204 blockade. DCs from SRA/CD204-deficient mice were more immunogenic in generating antitumor responses to B16 melanoma, compared with DCs from wild-type mice. Similarly, siRNA-mediated knockdown of SRA/CD204 by lentiviral vectors improved the ability of wild-type DCs to stimulate the expansion and activation of CD8(+) T cells specific for idealized or established melanoma antigens in mice. Using SRA/CD204-silenced DCs to generate antigen-targeted vaccines, we documented a marked increase in the level of antitumor immunity achieved against established B16 tumors and metastases. This increase was associated with enhanced activation of antigen specific CTLs, greater tumor infiltration by CD8(+) T cells and NK cells, and increased intratumoral ratios of both CD4(+) and CD8(+) T-effector cells to CD4(+)CD25(+) T-regulatory cells. Our studies establish that downregulating SRA/CD204 strongly enhances DC-mediated antitumor immunity. In addition, they provide a rationale to enhance DC vaccine potency through SRA/CD204-targeting approaches that can improve clinical outcomes in cancer treatment.     

Dendritic cells transduced with tumor-associated antigen gene elicit potent therapeutic antitumor immunity: comparison with immunodominant peptide-pulsed DCs

Several studies have shown that vaccine therapy using dendritic cells (DCs) pulsed with specific tumor antigen peptides can effectively induce antitumor immunity. Peptide-pulsed DC therapy is reported to be effective against melanoma, while it is still not sufficient to show the antitumor therapeutic effect against epithelial solid tumors such as gastrointestinal malignancies. Recently, it has been reported that vaccine therapy using DCs transduced with a surrogate tumor antigen gene can elicit a potent therapeutic antitumor immunity. In this study, we investigated the efficacy of vaccine therapy using DCs transduced with the natural tumor antigen in comparison with peptide-pulsed DCs. DCs derived from murine bone marrow were adenovirally transduced with murine endogenous tumor antigen gp70 gene, which is expressed in CT26 cells, or DCs were pulsed with the immunodominant peptide AH-1 derived from gp70. We compared these two cancer vaccines in terms of induction of antigen-specific cytotoxic T lymphocyte (CTL) responses, CD4+ T cell response against tumor cells, migratory capacity of DCs and therapeutic immunity in vivo. The cytotoxic activity of splenocytes against CT26 and Meth-A pulsed with AH-1 in mice immunized with gp70 gene-transduced DCs was higher than that with AH-1-pulsed DCs. CD4+ T cells induced from mice immunized with gp70 gene-transduced DCs produced higher levels of IFN-gamma by stimulation with CT26 than those from mice immunized with AH-1-pulsed DCs (p < 0.0001), and it was suggested that DCs transduced with tumor-associated antigen (TAA) gene induced tumor-specific CD4+ T cells, and those CD4+ T cells played a critical role in the priming phase of the CD8+ T cell response for the induction of CD8+ CTL. Furthermore, DCs adenovirally transduced with TAA gene showed an enhancement of expression of CC chemokine receptor 7 and improved the migratory capacity to draining lymph nodes. In subcutaneous models, the vaccination using gp70 gene-transduced DCs provided a remarkably higher therapeutic efficacy than that using AH-1-pulsed DCs. These results suggested that vaccine therapy using DCs adenovirally transduced with TAA gene can elicit potent antitumor immunity, and may be useful for clinical application.     

A universal anti-cancer vaccine: Chimeric invariant chain potentiates the inhibition of melanoma progression and the improvement of survival

For many years, clinicians and scientists attempt to develop methods to stimulate the immune system to target malignant cells. Recent data suggest that effective cancer vaccination requires combination immunotherapies to overcome tumor immune evasion. Through presentation of both MHC-I and II molecules, DCs-based vaccine platforms are effective in generating detectable CD4 and CD8 T cell responses against tumor-associated antigens. Several platforms include DC transfection with mRNA of the desired tumor antigen. These DCs are then delivered to the host and elicit an immune response against the antigen of interest. We have recently established an mRNA genetic platform which induced specific CD8⁺ cytotoxic T cell response by DC vaccination against melanoma. In our study, an MHC-II mRNA DCs vaccine platform was developed to activate CD4⁺ T cells and to enhance the anti-tumor response. The invariant chain (Ii) was modified and the semi-peptide CLIP was replaced with an MHC-II binding peptide sequences of melanoma antigens. These chimeric MHC-II constructs are presented by DCs and induce proliferation of tumor specific CD4⁺ T cells. When administered in combination with the MHC-I platform into tumor bearing mice, these constructs were able to inhibit tumor growth, and improve mouse survival. Deciphering the immunological mechanism of action, we observed an efficient CTLs killing in addition to higher levels of Th1 and Th2 subsets in the groups immunized with a combination of the MHC-I and MHC-II constructs. These universal constructs can be applied in multiple combinations and offer an attractive opportunity to improve cancer treatment.     

Intratumoral injection of immature dendritic cells enhances antitumor effect of hyperthermia using magnetic nanoparticles

Dendritic cells (DCs) are potent antigen-presenting cells that play a pivotal role in regulating immune responses in cancer and have recently been shown to be activated by heat shock proteins (HSPs). We previously reported that HSP70 expression after hyperthermia induces antitumor immunity. Our hyperthermia system using magnetite cationic liposomes (MCLs) induced necrotic cell death that was correlated with HSP70 release. In the present study, we investigated the therapeutic effects of DC therapy combined with MCL-induced hyperthermia on mouse melanoma. In an in vitro study, when immature DCs were pulsed with mouse B16 melanoma cells heated at 43 degrees C, major histocompatibility complex (MHC) class I/II, costimulatory molecules CD80/CD86 and CCR7 in the DCs were upregulated, thus resulting in DC maturation. C57BL/6 mice bearing a melanoma nodule were subjected to combination therapy using hyperthermia and DC immunotherapy in vivo by means of tumor-specific hyperthermia using MCLs and directly injected immature DCs. Mice were divided into 4 groups: group I (control), group II (hyperthermia), group III (DC therapy) and group IV (hyperthermia + DC therapy). Complete regression of tumors was observed in 60% of mice in group IV, while no tumor regression was seen among mice in the other groups. Increased cytotoxic T lymphocyte (CTL) and natural killer (NK) activity was observed on in vitro cytotoxicity assay using splenocytes in the cured mice treated with combination therapy, and the cured mice rejected a second challenge of B16 melanoma cells. This study has important implications for the application of MCL-induced hyperthermia plus DC therapy in patients with advanced malignancies as a novel cancer therapy.     

Dendritic cell-tumor cell hybrids enhance the induction of cytotoxic T lymphocytes against murine colon cancer: a comparative analysis of antigen loading methods for the vaccination of immunotherapeutic dendritic cells

Dendritic cells (DCs) have been used successfully for inducing effective anti-tumor immune responses in advanced cancer patients undergoing tumor-specific immunotherapy. Appropriate antigen pulsing is a crucial parameter for optimizing the efficacy of immunotherapy as well as anti-tumor protection therapy. Using a murine colon cancer model, we evaluated the anti-tumor efficacy of four different preparations of DC vaccines that contained either a whole tumor or its derivatives, including i) DCs pulsed with tumor lysate, ii) DCs pulsed with necrotic tumor cells, iii) DCs pulsed with apoptotic tumor cells, and iv) DC-tumor cell fusion hybrids. Our data show that DC-tumor cell fusion hybrids and DCs pulsed with irradiated apoptotic tumor cells were more potent than DCs with freeze-thawed necrotic tumor cells for the induction of protective anti-tumor responses. The vaccination of DCs pulsed with tumor lysate failed to elicit any anti-tumor effect. In animals administered with higher doses of a tumor-cell challenge, DC-tumor cell fusion hybrids elicited the most effective anti-tumor response. Among the preparations tested, mice immunized with DC-tumor cell fusion hybrids resulted in the greatest induction of cytotoxicity as measured by the cytotoxic T lymphocyte activity of both the splenocytes and the Thy1.2-positive T lymphocytes. Furthermore, the in vitro production of IFN-gamma polarized to the Th1 cytokine responses was highest in the splenocytes derived from mice vaccinated with DC-tumor cell fusion hybrids. Our results suggest that DC-tumor cell fusion hybrids are more potent inducers of protection against solid tumors, such as colon cancer, than other antigen-loading strategies using whole tumor cell materials.