4-1BBL基因修饰colon26细胞的体内抗肿瘤作用

背景与目的:研究4-1BBL基因修饰的小鼠结肠癌细胞瘤苗在小鼠体内诱导产生免疫反应及抗肿瘤效应的能力. 材料与方法:采用脂质体介导法将真核表达质粒pMKIT/4-1BBL导人小鼠结肠癌细胞colon26,经G418筛选后获得4-1BBL稳定高表达细胞克隆colon26/4-1BBL和空载体细胞克隆colon26/pMKITneo,以丝裂霉素C处理,制成癌细胞瘤苗.将野生型colon26、eolon26/pMKITneo和colon26/4-IBBL细胞分别接种于BALB/c小鼠右侧背部皮下,观察细胞致瘤性.取MMC处理的colon26细胞、colon26/pMKITneo细胞和colon26/4-1BBL细胞,分别腹腔免疫BALB/c小鼠,采用改良MTT法测定CTL和NK细胞杀伤活性,取血清用ELISA法测定IL-2、IFN-γ含量.于BALB/c小鼠皮下接种colon26细胞制备早期癌模型,第2 d腹腔注射colon26/4-1BBL瘤苗,7 d后再注射1次,观察肿瘤生长情况.结果:与野生型colon26和colon26/pMKITneo细胞相比,colon26/4-1BBL细胞在小鼠体内的致瘤性明显下降,表现为肿瘤结节出现时间延迟,肿瘤体积明显小于对照组(P＜0.05).MMC处理的肿瘤细胞瘤苗免疫小鼠后,colon26/4-1BBL组小鼠CTL和NK细胞的杀伤活性明显增高(P＜0.05);血清IL-2和IFN-γ的含量明显增高(P＜0.01);而且能对亲本肿瘤细胞colon26产生免疫保护作用,大部分小鼠能保持无瘤状态长期存活(100 d以上).colon26/4-1BBL瘤苗治疗后,部分小鼠保持无瘤生存,成瘤小鼠肿瘤生长缓慢,小鼠生存期明显延长(＞70 d).结论:4-1BBL基因修饰的小鼠结肠癌细胞瘤苗能显著增强小鼠的免疫功能,并能产生显著的抗肿瘤作用.     

转4-1BBL 基因的小鼠肝癌细胞瘤苗刺激脾细胞产生细胞因子的研究

 目的 研究转4-1BBL基因的小鼠肝癌细胞瘤苗体外刺激同系小鼠脾细胞产生细胞因子（IL-2、TNF-α和GM-CSF）的能力。方法 以丝裂霉素C（MMC）处理高表达转m4-1 BBL基因的小鼠Hepa1-6肝癌细胞，制成肿瘤细胞瘤苗（TCV），体外与同系小鼠脾淋巴细胞共同培养后，观察其对脾细胞产生细胞因子（IL-2、TNF-α和GM—CSF）的影响。结果 TCV-4-1 BBL刺激后，脾细胞体外分泌细胞因子IL-2、TNF-α和GM-CSF的水平明显增高。结论 转4-1BBL基因的小鼠肝癌细胞瘤苗能刺激脾细胞产生细胞因子IL-2、TNF-α和GM-CSF。     

自体肿瘤瘤苗对荷瘤鼠Th1、Th2型细胞因子及细胞毒作用的影响

目的研究经处理的H22肝癌细胞肿瘤瘤苗作为全细胞瘤苗对H22荷瘤小鼠体内Th1/Th2细胞比例和细胞因子的影响以及CTL的杀伤活性.方法用加重组白细胞介素2、重组粒细胞单核细胞集落刺激因子及福氏不完全佐剂制成疫苗,建立荷瘤小鼠模型,用51Cr释放法测定瘤苗免疫组、荷瘤组、正常组小鼠脾细胞对亲本H22肝癌细胞的杀伤活性;流式细胞仪检测单个核细胞中的Th1和Th2细胞,并取血检测血清中IL-10、IFN-γ水平.结果效靶比为200:1时,免疫小鼠脾细胞体外杀伤亲本H22肝癌细胞的杀伤率为38.3%,显著高于荷瘤组的13.6%,正常组的7.5%,以及对S180细胞的9.1%(P均＜0.05).瘤苗免疫组Th1细胞及Th1/Th2细胞的比值显著升高(P＜0.01),血清IFN-γ较对照组明显升高(P＜0.01);血清IL-10较对照组明显降低(P＜0.01).结论肿瘤细胞加小剂量IL-2和GM-CSF及佐剂组成的肿瘤细胞瘤苗可激发特异性细胞介导的免疫反应,改善抗肿瘤免疫反应.     

表达CD40L的小鼠结肠癌colon26瘤苗增强DC活性

目的：观察表达CD40L的小鼠结肠癌colon26瘤苗体内外对DC活性的影响。方法：以脂质体法将CD40L基因转染colon26细胞获得稳定表达CD40L的colon26/CD40L瘤苗。colon26/CD40L细胞与小鼠骨髓来源DC共培养,流式细胞术检测DC表型变化,RT-PCR法检测细胞因子基因P19、P35、P40、IL-18和IFN-γ的表达,ELISA法检测共培养上清中IL-12、IL-23和IFN-γ的水平。BALB/c小鼠皮下注射colon26细胞制备荷瘤小鼠模型,colon26/CD40L致敏DC治疗荷结肠癌小鼠,ELISA法检测荷瘤小鼠外周血中IL-12、IL-23、IFN-γ、IL-10和TGF-β的水平,H-E染色观察肝、脾和肿瘤组织的病理学变化。结果：成功获得高表达CD40L的丝裂霉素（MMC)处理的colon26/CD40L瘤苗。DC与colon26/CD40L瘤苗共培养后,DC表面共刺激分子CD80、CD86、MHCⅠ和MHCⅡ表达增高（P<0.01）;共培养体系中可检测到P19、P35、P40、IL-18和IFN-γ mRNA的表达,而在其他组未检测到上述基因的表达;共培养细胞上清中有较高水平的IL-12、IL-23和IFN-γ（P<0.01）。colon26/CD40L瘤苗致敏DC治疗组与colon26/CD40L瘤苗治疗组、DC治疗组比较,小鼠移植瘤的体积和质量明显减小和减少（P<0.05）;小鼠外周血IL-12、IL-23和IFN-γ明显升高（P<0.01）,IL-10和TGF-β明显降低（P<0.01）;小鼠移植瘤组织病理变化显著减轻。结论：表达CD40L的丝裂霉素（MMC)处理的结肠癌瘤苗可促进DC的成熟,刺激DC分泌细胞因子,增强DC体内外活性,从而增强治疗体系的抗肿瘤免疫效应。     

Caveolin1对KDR信号通路的作用

目的:研究以小鼠结肠癌细胞CT-26RNA作为抗原体外转染经mIL-12基因修饰的树突状细胞(dendriticcells,DC),观察其诱导特异性抗肿瘤的效应。方法:小鼠骨髓细胞体外以rmGM-CSF、rmIL-4诱导培养获取树突状细胞,流式细胞术检测纯度;293细胞扩增携带mIL-12基因的重组腺病毒,体外转染树突状细胞;Trizol法提取CT-26细胞总RNA,应用Trans-Messenger体外转染mIL-12基因修饰的树突状细胞,免疫接种小鼠。ELISA法检测细胞上清及小鼠血液中mIL-12水平,LDH释放法检测小鼠体内细胞毒性T淋巴细胞(CTL)杀伤活性。结果:小鼠骨髓细胞经诱导培养后,获得大量高纯度的树突状细胞,流式细胞术检测CD11c 的树突状细胞>90%;提取的CT-26细胞总RNA体外经TransMessenger介导,转染mIL-12基因修饰的树突状细胞后,回输小鼠,可以诱导体内生成较高水平的特异性CTL活性,亲本肿瘤接种后小鼠100%长期存活,而以该RNA转染Ad-LacZ修饰DC后的对照组及RNA转染DC的对照组,诱导机体生成的特异性CTL活性显著低于实验组(P<0.01),亲本肿瘤接种后小鼠60%长期存活,DC、PBS对照组则均未诱导机体生成特异性CTL活性,小鼠无长期存活。结论:树突状细胞经小鼠结肠癌CT26细胞RNA转染和mIL-12基因修饰后免疫接种小鼠,可在体内有效提呈肿瘤抗原,诱导机体产生高水平的CTL,更有效地诱发特异性抗肿瘤效应。     

基于Survivin的模拟病毒瘤苗体外激发CTL杀伤活性的实验研究

目的探讨基于Survivin的模拟病毒瘤苗体外激发细胞毒性T细胞(cytotoxicTlymphocytes,CTL)对乳腺癌细胞的杀伤作用。方法制备含有Survivin的模拟病毒瘤苗,体外刺激HLA-A2·1阳性健康者外周血单个核细胞(peripheralbloodmononu-clearcell,PBMC),用酶联免疫斑点实验(enzymelinkedimmunospotassay,ELISPOT)和标准51Cr释放实验分别检测瘤苗所诱导的特异性CTL活性。结果Survivin模拟病毒瘤苗能够在体外诱导出特异性CTL,对HLA-A2·1阳性的乳腺癌细胞系MCF-7有明显的杀伤毒性,杀伤率为56·4%;并可诱导CTL产生IFN-γ等细胞因子,ELISPOT显示斑点数为287个/105细胞,P<0·05。结论模拟病毒瘤苗能有效激发出特异性CTL应答,为新型乳腺癌治疗性疫苗的设计提供了新思路。     

肝癌树突状细胞瘤苗诱导抗肿瘤作用的研究

目的：研究负载肝癌抗原的肝癌树突状细胞（dendritic cell,DC）瘤苗诱导的抗肿瘤作用。方法：于体外用rhGM-CSF和rhIL-4从肝癌患者外周血诱导DC,并用肝癌细胞抗原冲击致敏,制成负载肝癌抗原的肝癌DC瘤苗。肝癌DC瘤苗活化自体T淋巴细胞分化为细胞毒性T淋巴细胞（cytotoxic of T-lymphocytes,CTL）,采用流式细胞术检测CTL分型;乳酸脱氢酸（LDH）4 h释放法检测CTL对肝癌细胞的特异性杀伤作用。MTT法检测肝癌DC瘤苗及其活化CTL培养上清对肿瘤细胞的抑制作用;ELISA法检测肝癌DC瘤苗活化的CTL培养上清中IL-12、IFN-γ和TNF-α水平。结果：经肝癌DC瘤苗活化后的T淋巴细胞群中,CD56^＋细胞数量显著减少,CD4^＋T和CD8^＋T细胞数量增加,其中以CD8^＋T细胞增加较明显;细胞毒实验显示,该CTL对自体肝癌细胞具有较强的杀伤作用,而对与致敏DC的肝癌抗原无关的CT26结肠腺癌细胞无明显杀伤作用;单纯肝癌DC瘤苗或其激活的CTL培养上清也表现出较强的抑瘤作用,而且这种抑瘤作用具有广谱性,可抑制多种肿瘤细胞的生长;在CTL培养上清中可检测到IL-12、TNF-α和IFN-γ的含量。结论：肝癌DC瘤苗不仅诱导了对肝癌细胞的特异性CTL杀伤作用,而且可激活CD4^＋T和CD8^＋T细胞分泌IL-12、TNF-α和IFN-γ等细胞因子,以非杀伤方式直接或间接地抑制肿瘤细胞生长,发挥非特异性的抗肿瘤作用。     

gp96-肽复合物体外诱导CTL反应及其抗肿瘤效应研究

目的研究小鼠肝癌腹水瘤H22细胞来源的gp96-肽复合物体外诱导小鼠脾淋巴细胞特异性细胞毒T细胞的产生及其抗肿瘤效应.方法利用蛋白提取纯化技术、Western-blot法、细胞培养技术、流式细胞术、CCK-8法、RT-PCR法等研究gp96-肽复合物体外诱导扩增CTL及其抗肿瘤效应.结果流式细胞仪检测表明,经gp96-肽复合物诱导后的CD8 T细胞比例达到近70%,远远高于对照组的35%、26%.该活化的CTL细胞在效靶比为50:1时的肿瘤杀伤率达72%与对照组相比具有统计学意义;将活化的CTL细胞回输小鼠体内能产生对该肿瘤细胞良好的过继性免疫保护,延长荷瘤小鼠的生存时间;RT-PCR法检测该活化的脾细胞较正常脾淋巴细胞高表达IFN-γ mRNA.结论肿瘤来源的热休克蛋白gp96-肽复合物能诱导小鼠脾淋巴细胞的CTL反应,并增强脾细胞 IFN-γ mRNA的表达,该CTL具有特异性抗H22肿瘤细胞的免疫保护作用.     

髓系抑制性细胞对神经母细胞瘤抗原特异性细胞毒性T淋巴细胞体外增殖和杀伤抑制作用北大核心CSCD

目的探讨髓系抑制性细胞(myeloid-derived suppressor cell,MDSC)对神经母细胞瘤抗原特异性细胞毒性T淋巴细胞(cytotoxic T lymphocyte,CTL)体外增殖和杀伤活性的影响。方法体外培养神经母细胞瘤SK-N-SH细胞、自BALB/c小鼠分离培养树突状细胞(dendritic cell,DC)和CD3+T细胞,制备DC诱导的神经母细胞瘤抗原特异性CTL。分离纯化小鼠MDSC,将CTL与MDSC混合培养,采用CFSE荧光染色和流式细胞学方法,检测MDSC对CTL增殖抑制情况。将CTL与SK-N-SH、MDSC混合培养,ELISA法检测不同组CTL对SK-N-SH杀伤率及上清液中IL-2和IFN-γ分泌情况。结果磁珠分选纯化后Gr-1+CD11b+MDSC细胞比例为84.6%。负载抗原的CTL细胞上清液中IL-2和IFN-γ含量较单纯培养T细胞上清液中IL-2和IFN-γ含量明显增高(P<0.05)。与MDSC共培养的CTL细胞增殖明显受抑;而单独培养CTL随时间延长细胞增殖明显。MDSC+CTL+SK-N-SH组杀伤率较CTL+SK-N-SH组明显降低(t=6.506,P<0.001);两组上清液中IL-2和IFN-γ分泌量差异亦有统计学意义(均P<0.01)。结论 MDSC可抑制神经母细胞瘤抗原特异性CTL的体外增殖和活性而产生免疫耐受,抑制CTL对神经母细胞瘤细胞的杀伤作用。     

CB6F1小鼠树突状细胞诱导细胞毒性T淋巴细胞的杀伤作用

[目的]探讨CB6F1小鼠脾树突状细胞(DC)的培养及其诱导针对小鼠路易斯肺癌(LLC)的细胞毒性T淋巴细胞(CTL)对肿瘤的杀伤效应.[方法]应用CB6F1小鼠脾细胞在GM-CSF、IL-4等细胞因子作用下培养出DC,反复冻融法制备LLC抗原致敏DC,与淋巴细胞及IL-2混合培养诱导出肿瘤特异性CTL,利用乳酸脱氢酶法检测CTL的杀伤活性.[结果]用GM-CSF、IL4联合培养小鼠脾细胞第4d,可见细胞形态发生改变,培养第8d,可见典型的刺突样DC,通过流式细胞术检测了DC表型高表达CD80占76.5％,CD86占60.0％,MHCⅡ占67.4％,CD11C占80.6％.[结论]应用GM-CSF、IL-4、LPS等细胞因子培养CB6F1小鼠脾细胞经过肿瘤抗原冲击,可以培养出成熟DC,并且DC可以诱导出具有杀伤活性的肿瘤特异性CTL.     

Tumor cell lysate-pulsed dendritic cells induce a T cell response against colon cancer in vitro and in vivo

To investigate whether tumor cell lysate-pulsed (TP) dendritic cells (DCs) induce cytotoxic T lymphocyte (CTL) activity against colon cancer in vitro and in vivo. Hematopoietic progenitor cells were magnetically isolated from BALB/c mice bone marrow cells. These cells were cultured with cytokines GM-CSF, IL-4, and TNFα to induce their maturation. They were analyzed by morphological observation and phenotype analysis. DCs were pulsed with tumor cell lysate obtained by rapid freezing and thawing at a 1:3 DC:tumor cell ratio. CTL activity and interferon gamma (IFNγ) secretion was evaluated ex vivo. In order to determine whether or not vaccination with CT26 TP DCs induce the therapeutic potential in the established colon tumor model, CT26 colon tumor cells were implanted subcutaneously (s.c.) in the midflank of naïve BALB/c mice. Tumor-bearing mice were injected with vaccination with CT26 TP DCs on days 3 and 10. Tumor growth was assessed every 2–3 days. Finally, CTL activity and IFNγ secretion were evaluated in immunized mice. Hematopoietic progenitor cells from mice bone marrow cells cultured with cytokines for 8 days showed the character of typical mature DCs. Morphologically, these cells were large with oval or irregularly shaped nuclei and with many small dendrites. Phenotypically, FACS analysis showed that they expressed high levels of MHC II, CD11b, CD80, and CD86 antigen, and were negative for CD8α. However, immature DCs cultured with cytokines for 5 days did not have typical DCs phenotypic markers. Ex vivo primed T cells with CT26 TP DCs were able to induce effective CTL activity against CT26 tumor cells, but not B16 tumor cells (E:T = 100:1, 60.36 ± 7.11% specific lysis in CT26 group vs. 17.36 ± 4.10% specific lysis in B16 group), and produced higher levels of IFNγ when stimulated with CT26 tumor cells but not when stimulated with B16 tumor cells (1210.33 ± 72.15 pg/ml in CT26 group vs. 182.25 ± 25.51 pg/ml in B16 group, P < 0.01). Vaccination with CT26 TP DCs could induce anti-tumor immunity against CT26 colon tumor in murine therapeutic models (tumor volume on day 19: CT26 TP DCs 342 ± 55 mm³ vs. the other control groups, P < 0.05). In addition, all splenic CD3⁺ T cells obtained from mice vaccinated with CT26 TP DCs produced high levels of IFNγ and shown specific cytotoxic activity against CT26 tumor cells, but no cytotoxic activity when stimulated with B16 tumor cells. Tumor cell lysate-pulsed DCs can induce tumor-specific CTL activity against colon cancer in vitro and in vivo.     

Anti-tumor immune response induced by dendritic cells transduced with truncated PSMA IRES 4-1BBL recombinant adenoviruses

Up-regulation of receptor–ligand pairs during interaction of a peptide-bound MHC complex on dendritic cells (DCs) with cognate TCR may amplify, sustain, and drive diversity in the ensuing T cell immune response. Members of the TNF ligand superfamily and the TNFR superfamily contribute to this costimulatory molecule signaling. In the present study, we used replication deficient adenoviruses to introduce a tumor-associated Ag (a truncated human prostate-specific membrane antigen (tPSMA)) and the T cell costimulatory molecule 4-1BBL into murine DCs, and observed the ability of these recombinant DCs to elicit tPSMA-directed T-cell responses in vitro and anti-tumor immunity to RM-1-tPSMA in a murine tumor model. Infection of DCs with Ad-tPSMA-IRES-m4-1BBL induced tPSMA-specific proliferative responses and up-regulated CD80 and CD86 s signaling molecules. The cytotoxic T lymphocytes activated by the Ad-tPSMA-IRES-m4-1BBL-transfected DCs showed significantly higher IFN-γ production and cytotoxicity against the RM-1 cells transfected with tPSMA. Moreover, vaccination of mice with Ad-tPSMA-IRES-m4-1BBL-transfected DCs induced a potent protective and therapeutic anti-tumor immunity to RM-1-tPSMA in a tumor model. These results demonstrated that development of DCs engineered to express tPSMA and 4-1BBL by recombinant adenovirus-mediated gene transfer may offer a new strategy for prostate cancer immunotherapy.     

过继回输腺病毒介导的白细胞介素10基因转染CTL对机体抗肿瘤免疫功能的增强效应

本研究探讨了白细胞介紊10(IL-10)对小鼠体内抗肿瘤免疫功能的影响。鉴于C26结肠癌细胞转染了IL-10基因后在体内的致瘤性明显下降，本研究构建了一株对C26结肠癌细胞具有杀伤括性的CD8^ CTL并观察了IL-10基因转染的该细胞株对肿瘤的治疗作用。携带IL-10基因的重组腺病毒能有效介导小鼠琳巴细胞的基因转染并使之分泌较高水平的IL-10。IL-10基因转染的CTL过继回输荷瘤小鼠体内能明显增强荷瘤小鼠的体内抗肿瘤免疫功能，使实验性肺转移小鼠肺部转移结节数明显减少．这表明，IL-10对于过继回输的肿瘤特异性CTL的免疫功能具有明显的增强作用。     

SCF或（和）GM—CSF体内基因转染对“自杀基因”疗法抗肿瘤作用的增？…

目的 通过增强体内抗原提呈功能提高“自杀基因”疗法疗效,探讨其相关免疫学机理。方法 采用腺病毒介导的ＳＣＦ,ＧＭ－ＣＳＦ基因体内转染联合ＣＤ／５ＦＣ“自杀基因”疗法治疗小鼠的ＣＴ２６结肠腺癌,观察肿瘤的生长和荷瘤小鼠的存活期,不同方法所诱导的ＣＴＬ杀伤活性及肿瘤局部的细胞因子表达。结果 一次性低剂量腺病毒介导的ｍＧＭ－ＣＳＦ或（和）ｍＳＣＦ基因的体内转染,能增强“自杀基因”疗法的疗效,在肿瘤局部出     

转染4-1BBL基因的胃癌细胞在小鼠体内的抗肿瘤及免疫调节作用

目的:观察转染4-1BBL基因的小鼠胃癌细胞株MFC的体内致瘤性及其对小鼠免疫功能的影响。方法:通过脂质体介导以重组质粒pMKITneo和pMKITneo/4-1BBL转染小鼠胃癌细胞株MFC。用RT-PCR法检测目的基因的表达。计数法绘制体外培养细胞生长曲线。将转染前后肿瘤细胞,分别接种于615小鼠背部皮下观察其致瘤性。流式细胞仪测定荷瘤小鼠外周血NK、CD4 T和CD8 T细胞数,并测定荷瘤小鼠肿瘤结节内细胞凋亡率。结果:MFC/4-1BBL细胞中可检测到4-1BBLmRNA表达。转染前后肿瘤细胞的体外生长速度无明显变化。MFC/4-1BBL细胞在小鼠体内的致瘤性较MFC/pMKITneo细胞和野生型MFC细胞明显降低。接种MFC/4-1BBL细胞的小鼠外周血NK细胞及CD8 T细胞数明显增多;其肿瘤结节内细胞凋亡率亦明显增高。结论:转染4-1BBL基因后并未影响MFC细胞的体外生长,但其在小鼠体内的致瘤性明显降低。MFC/4-1BBL细胞可诱导荷瘤小鼠体内CD8 T和NK细胞增殖,而且能促进肿瘤细胞的凋亡。     

Murine sarcoma virus (MSV)-induced tumors in mice. I. Distribution of MSV-immune cytolytic T lymphocytes in vivo.

Quantitative studies using a 51Cr release assay were performed to analyse the time-course of appearance and specificity of cytolytic cells in C57Bl/6 mice inoculated with Moloney murine sarcoma virus (MSV). Various lymphoid organs were studied including spleen, mesenteric lymph nodes (MLN), lymph nodes regional to the MSV-induced tumor (RLN), and peripheral blood. Furthermore, the kinetics of appearance of cytolytic cells within the MSV-induced tumor was determined. In agreement with previous studied, it was found that cytolytic T lymphocytes (CTL) specific for MSV-associated antigens were present among the cells extracted from the tumor and from the lymphoid organs. However, differences in the kinetics of CTL activity could be documented: lymphoid cells from spleen, RLN and peripheral blood showed peak activity at the time of maximum tumor diameter, while intratumoral cells showed peak activity at the onset of tumor regression. MLN cells showed cytolytic activity only when tumor regression had begun. Naturally cytotoxic cell populations of thymus-independent origin, present in normal control mice, were also detected in MSV-infected mice.     

Recruitment and activation of tumor-specific immune T cells in situ: functional studies using a sponge matrix model

The activation of tumor-specific precursor cytotoxic T lymphocytes (CTLP) into cytotoxic T cells (CTL) was demonstrated in situ using the well-defined, highly metastatic ESb tumor as murine model system. Ten days after optimal immunization of syngeneic mice with a sublethal dose of live ESb tumor cells in the pinna, tumor-sensitized non-cytotoxic CTLP were recovered from the spleen and lymph nodes. These cells mature into tumor-specific CTL upon restimulation in vitro. Using a confined sponge matrix compartment, in combination with a specific tumor vaccine (autologous inactivated tumor cells), we induced a CD8+ (Lyt 2+) T-cell-mediated, highly cytotoxic anti-tumor immune response in situ in immunized mice. It was not possible to activate a similar response directly in lymphoid organs such as the spleen. The cytotoxic CD8+ T cells, recovered by simple mechanical pressing of the sponge, were active against the specific tumor cells in a 51Cr-release assay in vitro and also in a Winn neutralization assay in vivo. CTL activity was increased and remained in the non-adherent fraction when the cell mixture, squeezed out of the sponges, was passed over nylon wool. In a cell recruitment assay, the delayed-type hypersensitivity (DTH) potential of the activated sponge-infiltrating T cells was demonstrated by their capacity to recruit circulating host lymphocytes to sites of tumor-cell location in situ.     

Immunomodulatory gene therapy with interleukin 12 and 4-1BB ligand: long- term remission of liver metastases in a mouse model

BACKGROUND: The success of immunomodulatory cancer therapy is frequently hampered by the transient nature of the antitumor immune response. We have shown previously in a mouse model that interleukin 12 (IL-12) generates a strong natural killer (NK) cell-mediated antitumor response and reduces liver metastases induced by a colon carcinoma cell line. However, only a small percentage of the treated animals developed the cytotoxic T-lymphocytic response required for a long-term systemic antitumor immunity. 4-1BB is a co-stimulatory molecule expressed on the surface of activated T cells. Interaction of 4-1BB with its natural ligand (4-1BBL) has been shown to amplify T-cell (especially CD8+)-mediated immunity. In this study, we investigated the effects of adenovirus-mediated gene therapy delivering both IL-12 and 4-1BBL genes on mice with hepatic metastases induced by colon cancer cells. METHODS: Syngeneic BALB/c mice received intrahepatic injection of poorly immunogenic MCA26 colon cancer cells. Various combinations of replication-defective adenoviruses expressing IL-12 and 4-1BBL genes were injected into the established liver tumors. Changes in tumor size and animal survival were then monitored. All statistical tests were two-sided. RESULTS: The long-term survival rate of mice treated with the combination of IL-12 and 4-1BBL was significantly improved over that of animals in the control group (P =.0001). In vivo depletion of NK cells or CD8+ T cells completely abolished the long-term survival advantage of the IL-12 plus 4-1BBL-treated animals (P<.002). Moreover, the systemic immunity induced by this combination treatment protected these animals against a subcutaneous challenge with parental MCA26 cells. CONCLUSION: Adenovirus-mediated transfer of IL-12 and 4-1BBL genes directly into liver tumors resulted in tumor regression that required both NK and CD8+ T cells and generated a potent, long-lasting antitumor immunity.     

Regulation of CTL responses to MHC-restricted class I peptide of the gp70 tumour antigen by splenic parenchymal CD4+ T cells in mice failing immunotherapy with DISC-mGM-CSF

Direct intratumour injection of the disabled infectious single-cycle-herpes simplex virus-encoding murine granulocyte/macrophage colony-stimulating factor (DISC-HSV-mGM-CSF) into established colon carcinoma CT26 tumours induced complete tumour rejection in up to 70% of treated animals (regressors), while the remaining mice developed progressive tumours (progressors). This murine Balb/c model was used to dissect the cellular mechanisms involved in tumour regression or progression following immunotherapy. CTLs were generated by coculturing lymphocytes and parenchymal cells from the same spleens of individual regressor or progressor animals in the presence of the relevant AH-1 peptide derived from the gp70 tumour-associated antigens expressed by CT26 tumours. Tumour regression was correlated with potent CTL responses, spleen weight and cytokine (IFN-gamma) production. Conversely, progressor splenocytes exhibited weak to no CTL activity and poor IFN-gamma production, concomitant with the presence of a suppressor cell population in the progressor splenic parenchymal cell fraction. Further fractionation of this parenchymal subpopulation demonstrated that cells inhibitory to the activation of AH-1-specific CTLs, restimulated in vitro with peptide, were present in the nonadherent parenchymal fraction. In vitro depletion of progressor parenchymal CD3+/CD4+ T cells restored the CTL response of the cocultured splenocytes (regressor lymphocytes and progressor parenchymal cells) and decreased the production of IL-10, suggesting that CD3+CD4+ T lymphocytes present in the parenchymal fraction regulated the CTL response to AH-1. We examined the cellular responses associated with tumour rejection and progression, identifying regulatory pathways associated with failure to respond to immunotherapy.