CEA 迷你肽表位基因疫苗诱导小鼠抗肿瘤免疫的研究

目的:利用含有CEA625-667 基因的单倍体疫苗pcDNA-CEA625-667 及三串联体的DNA 疫苗pcDNA-triCEA625-667 免疫小鼠后,观察其诱导的抗肿瘤免疫效应。方法: 采用4 ~ 6 周纯系BALB/ c 小鼠,肌肉注射法分pc-DNA3.0、pcDNA-CEA625-667 、pcDNA-triCEA625-667 三组免疫小鼠,对其激发的机体特异性及非特异性免疫反应进行研究。流式细胞术检测免疫小鼠脾细胞的T 细胞亚群和CD4+ / CD8+比值;3 H-TdR 掺入法检测免疫小鼠的特异性淋巴细胞增殖;Western blot 杂交及ELISA法检测免疫小鼠血清中的CEA 特异性抗体;ELISA 法检测免疫动物脾细胞体外诱导IFN-β、IL-4、GM-CSF 的分泌水平。结果:实验组与对照组的CD4+ / CD8+比值差异无统计学意义;经过基因疫苗免疫的小鼠与天然小鼠相比,其脾细胞在体外与短肽共孵育之后,会在更短的时间内出现更明显的细胞增殖;免疫了CEA 迷你基因串联体肿瘤疫苗的小鼠血清中可以产生低滴度的抗体,提示HTL 的活化;免疫小鼠脾细胞上清中IFN鄄酌的含量明显高于对照组,而pc-DNA3.0,pcDNA-CEA625-667 ,pcDNA-tri-CEA625-667各组IL-4 的含量均很低,差异无统计学意义;迷你基因三倍体疫苗所引发的增殖效应以及释放细胞因子的水平均高于迷你基因一倍体,说明我们所采用将目的基因多倍串联的抗原改造的方式起到了增强免疫效应的作用。结论:CEA 迷你肽表位基因单倍体及三倍体疫苗均不能显著改变动物体内CD4/ CD8 比值,但均能诱导HTL 活化,使被免疫机体T 细胞趋向于Th1 效应且三倍体疫苗的免疫原性强于单倍体疫苗。     

CEA 迷你基因串联体疫苗的体内抗肿瘤活性观察

目的:观察已构建的含有CEA625-667 基因单倍体疫苗pcDNA-CEA625-667 及三串联体的DNA 疫苗pcDNA-triCEA625-667 对荷瘤小鼠体内肿瘤的抑制情况及小鼠存活时间的改变。方法:建立小鼠肝细胞癌实验动物模型,应用单倍体疫苗pcDNA-CEA625-667 及三串联体DNA 疫苗pcDNA-triCEA625-667 免疫小鼠,以生理盐水为对照组,观察各实验组小鼠皮下肿瘤生长情况,记录皮下肿瘤生长曲线,观察疫苗对荷瘤小鼠肿瘤生长速度的影响以及疫苗对荷瘤小鼠生存时间的影响。结果:与生理盐水对照组相比,两种疫苗均能明显抑制CEA 阳性荷瘤小鼠的肿瘤体积以及生长速度(P <0.01),其中,pcDNA-triCEA625-667 疫苗组的抑制作用明显优于pcDNA-CEA625-667 疫苗组(P<0.01),而二者均不能抑制CEA 阴性荷瘤小鼠的肿瘤生长。pcDNA-CEA625-667 疫苗组平均生存时间为(48.50±6.73)d,与生理盐水对照组(39.00±6.64)d 相比有显著差异(P<0.01);pcDNA-triCEA625-667 疫苗组生存时间(48.50依6.73)d 明显高于生理盐水对照组和pcDNA-CEA625-667 疫苗组(P<0.01)。两组疫苗均不能延长CEA 阴性荷瘤小鼠的生存时间。结论:无论是单倍体还是三串联体的DNA 疫苗,均能够明显抑制CEA 阳性荷瘤小鼠的肿瘤生长速度(P<0.01)及明显延长其生存时间(P<0.01),而对CEA 阴性荷瘤小鼠则无治疗作用。     

CEA抗原表位串联体与FL共表达基因疫苗抑制小鼠肝癌细胞体内生长的研究

目的:观察CEA抗原表位串联体与FL共表达基因疫苗抑制荷瘤小鼠肿瘤生长。方法:利用基因重组技术将CEA抗原表位三串联体和FL基因片段克隆到质粒pcDNA3.0上,肌注免疫BALB/c小鼠,观察重组基因疫苗对CEA阳性肿瘤的抑制作用、小鼠生存时间及其诱导小鼠杀伤效应细胞的活性。结果:pcDNA-triCEA625-667-sFL免疫组小鼠生存时间延长,肿瘤生长速度缓慢,瘤块较小,与对照组小鼠比较有显著性差异(P0.01);经pcDNA-triCEA625-667-sFL免疫的小鼠脾细胞对H22-CEA+的杀伤率明显升高,差异有显著性(P0.01)。结论:共表达三倍体CEA抗原表位和FL的基因疫苗可以有效抑制CEA阳性肿瘤在小鼠体内的生长,并增强小鼠杀伤效应细胞的活性。     

癌胚抗原基因重组疫苗的构建及免疫效果观察

目的：探讨含癌胚抗原（CEA）部分编码基因的真核重组质粒pIRES-CEAⅢ用于CEA阳性肿瘤免疫治疗可能性。方法：应用基因重组技术构建了含CEA信号肽和Ⅲ区编码序列的真核表达质粒pIRES，CEAⅢ，肌注免疫BALB／c小鼠，再分别应用野生型小鼠肝癌细胞H22及CEAcDNA全序列转染的Hn细胞进行小鼠皮下接种，观察基因重组疫苗对CEA阳性肿瘤的抑制作用及其诱导小鼠细胞毒性T淋巴细胞（CTL）特异性杀伤CEA阳性肿瘤细胞的能力。结果：pIRES-CEAⅢ真核重组质粒免疫组小鼠CEA阳性肿瘤的生长速度趋缓，瘤块较小，与对照组小鼠（免疫空载体质粒和接种野生型H控细胞）相比有明显差异（P〈0．05）；经pIRES-CEAⅢ重组质粒免疫的小鼠脾细胞对H22．CEA（＋）细胞的杀伤率明显升高，差异显著（P〈0．01）；但对H22细胞则没有明显的杀伤作用。结论：pIRES-CEAⅢ作为基因疫苗可以抑制CEA阳性肿瘤在小鼠体内的生长，诱导小鼠CTL对CEA阳性肿瘤细胞的特异性杀伤。     

CEA迷你基因原核表达及其诱导小鼠特异性淋巴细胞增殖的研究

目的 在原核细胞中表达人癌胚抗原(CEA)的迷你基因短肽,纯化及鉴定目的 蛋白,并检测其在小鼠体内的抗原性.方法 利用PCR技术从人基因组中得到一段来源于CEA的DNA序列,其中包含两个编码分别能被HLA-DR4/9、HLA-DR53以及HLA-DR4/7/9型别的人群所识别辅助性T细胞(HTL)表位的迷你基因,构建重组表达质粒pQE30-CEA625-667,在大肠杆菌M15中诱导表达.Westren Blot杂交鉴定、镍凝胶亲和层析法纯化目的 蛋白.3H-TdR掺入法检测目的 短肽诱导的小鼠淋巴细胞增殖反应.结果 CEA625-667短肽在大肠杆菌M15中以包涵体形式表达.Western-blot结果显示,在相对分子质量约6 700处有表达产物与6×his mAb特异性结合带.镍柱纯化后可得到纯化的目的 蛋白.3H-TdR掺入实验所得不同浓度的CEA625-667与小鼠脾细胞共孵育7～9 d后的刺激指数相继达到对照组的10倍以上.结论 成功诱导了CEA625-667短肽的原核表达,通过镍凝胶亲和层析法获得纯度较高的CEA625-667短肽,并证明在一定浓度下目的 短肽可于体外诱导小鼠的特异性淋巴细胞增殖.为CEA625-667迷你基因作为表位疫苗在抗肿瘤方面的进一步研究提供条件.     

B7-1基因转染小鼠肝癌细胞诱导的抗瘤效应研究

目的：研究共刺激分子B7-1在抗肿瘤免疫中的作用.方法：体外观察转染B7-1基因及空载体的小鼠肝癌细胞株H22与同源小鼠脾细胞混合培养后,测定淋巴细胞增殖指数、CTL,于小鼠皮下接种不同H22细胞后观察肿瘤生长情况.结果：转染B7-1基因的H22细胞体外可刺激淋巴细胞增殖,增强CTL的杀伤活性,接种小鼠后成瘤潜伏期和荷瘤鼠存活期明显延长（P＜0.05）.结论：转入B7-1基因的小鼠肝癌细胞H22能增强免疫原性,能有效诱导CTLs介导的抗肿瘤免疫反应.     

中国株HIV-1 gp120核酸疫苗的实验免疫研究

目的　探讨表达中国株HIV 1gp12 0基因的核酸疫苗在小鼠体内的免疫反应。方法　将表达HIV 1gp12 0的核酸疫苗质粒pVAXP经肌肉注射免疫Balb c小鼠 ,检测免疫小鼠脾CD4 +、CD8+T细胞亚群的数量 ,脾特异性CTL杀伤活性和血清抗体滴度。结果　重组质粒pVAXP免疫组小鼠脾CD4 +、CD8+T细胞亚群的数值均比对照组高 (P <0 .0 5 ) ;免疫组脾特异性CTL杀伤活性与对照组相比差异极显著 (P <0 .0 1) ;血清抗体滴度显著高于对照组 (P <0 .0 5 )。结论　表达HIV 1gp12 0基因的核酸疫苗质粒pVAXP能诱导小鼠产生特异性细胞和体液免疫。     

IL-2的真核表达载体对乙肝病毒基因疫苗的免疫佐剂效应

单以乙肝病毒S区基因疫苗 (pCR3 1 S)或联合IL 2真核表达载体 (pDOR IL 2 )注射BALB/c小鼠 (H 2 d)股四头肌 ,ELISA法检测小鼠血清抗HBs,4h51Cr释放法检测小鼠脾细胞CTL活性。免疫 8周后 ,单注射pCR3 1 S及共注射IL 2真核表达载体的小鼠血清 45 0nmA值分别为 1 2 4± 0 1及 1 98± 0 17。CTL细胞杀伤活性分别为 (5 0 5± 6 4) %、 (6 1 9± 7 1) % ,两组均有明显差异 (P <0 0 1)。脾细胞悬液经抗CD4+ 单克隆抗体处理后CTL细胞杀伤活性分别为 (4 8 3± 5 9) %、 (5 6 2±6 1) % ,抗CD8+ 单克隆抗体处理后分别为 (10 6± 1 4) %、 (13 6± 1 3) %。结果表明 ,IL 2的真核表达载体能够提高小鼠对DNA疫苗的免疫应答 ,CTL细胞杀伤活性主要由CD8+ 执行。基因疫苗可能用于预防及治疗HBV感染。     

HIV DNA疫苗与重组腺病毒伴随病毒联合免疫效果的研究

目的 构建含HIV-1B亚型中国株gagV3基因的DNA疫苗及重组腺病毒伴随病毒(rAAV)疫苗，并研究DNA疫苗和rAAV联合免疫的免疫效果。方法 将HIV-1B亚型中国株gagV3基因克隆入真核表达载体pCI-neo上，构建了含HIV-1 gagV3基因的DNA疫苗pCI-gagV3。采用电击法将pCI-gagV3质粒转染p815细胞，用G418压力筛选，得到转入重组质粒的细胞系p815-gagV3，用免疫酶法检测细胞系中HIV-1基因的表达。用该DNA疫苗进行小鼠免疫实验，检测免疫效果；用该DNA疫苗初次免疫，含同样gagV3基因的重组腺病毒伴随病毒rAAV-gagV3加强免疫，采用免疫酶法检测免疫小鼠血清中HIV-1特异性的抗体水平，用乳酸脱氢酶法检测免疫小鼠的HIV-1特异性CTL水平。结果 pCI-gagV3可以在p815细胞中表达HIV-1的基因，免疫BALB／c小鼠后可以在小鼠体内诱发HIV-1特异性的细胞和体液免疫反应。HIV-1特异性抗体滴度为1：20；效靶比为50：1时，CTL平均杀伤率为41．7％。pCI-gagV3与rAAV-gagV3联合免疫并不能明显提高抗体水平，但可以提高CTL反应，效靶比为50：1时，CTL平均杀伤率为61.3％，高于单独用DNA疫苗或重组AAV疫苗免疫后产生的CTL活性。结论 DNA疫苗与重组腺病毒伴随病毒联合免疫可以提高免疫小鼠产生的HIV-1特异性CTL反应。     

共刺激分子4-1BBL基因免疫对HBsAg核酸疫苗诱导小鼠特异性免疫应答的影响

目的 研究共刺激分子4-1BBL基因免疫对HBsAg核酸疫苗诱导小鼠特异性体液和细胞免疫应答的影响.方法 将HBV表面抗原核酸疫苗pcDS2单独或联合共刺激分子4-1BBL质粒肌肉注射免疫C57BL/6小鼠;ELISA法检测小鼠血清抗-HBs IgG及亚型IgG1和IgG2a;迟发型超敏反应(DTH)反应检测体内细胞反应;流式细胞仪检测CD4+ T淋巴细胞分泌IL-4和IFN-γ及CD8+T淋巴细胞分泌IFN-γ水平;流式细胞仪检测小鼠脾细胞HBsAg特异性体外细胞毒性T淋巴细胞杀伤作用(CTL).结果 与单纯免疫核酸疫苗pcDS2组比较,pcDS2和4-1BBL联合免疫组小鼠的抗-HBs水平显著提高,抗-HBs IgG亚类以IgG2a占优;免疫小鼠经HBsAg脚掌皮下刺激后,联合免疫组小鼠脚掌的厚度显著高于pcDS2组;联合免疫组CD4+T淋巴细胞的IL-4和IFN-γ表达水平及CD8+T淋巴细胞的IFN-γ表达水平显著升高;DNA疫苗免疫的各组小鼠,HBsAg特异性体外CIL杀伤作用高于对照组,其中联合免疫组小鼠的体外CTL杀伤作用最强.结论共刺激分子4-1BBL不仅能增强HBV DNA疫苗诱导特异性体液免疫应答,还能增强特异性型细胞免疫反应,尤其增强体内CIL的杀伤活性.     

DNA vaccine expressing repeated carcinoembryonic antigen (CEA)(625-667) induces strong immunity in mice

The efficacy of immunization with DNA plasmids for single truncated carcinoembryonic antigen (CEA) peptide or triple repeated CEA peptides in mice was evaluated. A DNA fragment the truncated CEA gene (nucleotide 625-667) encoding two helper T lymphocyte (HTL) epitopes was amplified by PCR and cloned for generating recombinant plasmids for single CEA(625-667) (pcDNA-CEA(625-667)) or triple CEA(625-667) (pcDNA-triCEA(625-667)), respectively. Subsequently, groups of BALB/c female mice were intramuscularly injected with pcDNA-CEA(625-667,) pcDNA-triCEA(625-667) or control pcDNA3.0 vector, respectively. Ten days after the last immunization, the frequency of splenic CD4(+) and CD8(+) T cells in the mice was determined by flow cytometry. The antigen-specific proliferation of splenic T cells and cytokine production ex vivo were analyzed by (3)H-TdR uptake and cytokine ELISA, respectively. The levels of serum antibodies against CEA in the mice were detected by Western blot and ELISA. Although immunization with plasmid for the CEA(625-667) peptide(s) did not alter the frequency of CD4(+) and CD8(+) T cells in mice, vaccination with plasmid for CEA peptide induced strong antigen-specific T cell proliferation, particularly for the plasmid encoding the triple-repeated CEA peptides, accompanied by significantly elevated levels of IFN-γ secreted by T cells from the mice immunized with triple-repeated peptides. Furthermore, immunization with the plasmid for CEA peptide stimulated higher levels of antigen-specific antibody responses in mice. Vaccination with the plasmid for the triple repeated CEA peptides induced stronger Th1 responses. Our findings may be useful for the development of effective DNA vaccine for the immunotherapy of cancer.     

Induction of protective immunity to Listeria monocytogenes with dendritic cells retrovirally transduced with a cytotoxic T lymphocyte epitope minigene

In the present study, we developed a cytotoxic T lymphocyte (CTL) epitope minigene-transduced dendritic cell (DC)-based vaccine against Listeria monocytogenes. Murine bone marrow-derived DCs were retrovirally transduced with a minigene for listeriolysin O (LLO) 91-99, a dominant CTL epitope of L. monocytogenes, and were injected into BALB/c mice intravenously. We found that the DC vaccine was capable of generating peptide-specific CD8+ T cells exhibiting LLO 91-99-specific cytotoxic activity and gamma interferon production, leading to induction of protective immunity to the bacterium. Furthermore, we demonstrated that the retrovirally transduced DC vaccine was more effective than a CTL epitope peptide-pulsed DC vaccine and a minigene DNA vaccine for eliciting antilisterial immunity. These results provide an alternative strategy in which retrovirally transduced DCs are used to design vaccines against intracellular pathogens.     

Anti-idiotype antibody induced cellular immunity in mice transgenic for human carcinoembryonic antigen

In the present study, we have analysed the detailed cellular immune mechanisms involved in tumour rejection in carcinoembryonic antigen (CEA) transgenic mice after immunization with dendritic cells (DC) pulsed with an anti-idiotype (Id) antibody, 3H1, which mimics CEA. 3H1-pulsed DC vaccinations resulted in induction of CEA specific cytotoxic T lymphocyte (CTL) responses in vitro and the rejection of CEA-transfected MC-38 murine colon carcinoma cells, C15, in vivo (Saha et al.,Cancer Res 2004; 64: 4995-5003). These CTL mediated major histocompatibility complex (MHC) class I-restricted tumour cell lysis, production of interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha), and expression of Fas ligand (FasL) and TNF-related apoptosis-inducing ligand (TRAIL) in response to C15 cells. CTL used perforin-, FasL-, and TRAIL-mediated death pathways to lyse C15 cells, although perforin-mediated killing was the predominant lytic mechanism in vitro. The cytokines IFN-gamma and TNF-alpha synergistically enhanced surface expression of Fas, TRAIL receptor, MHC class I and class II on C15 cells that increased the sensitivity of tumour cells to CTL lysis. CTL activity generated in 3H1-pulsed DC immunized mice was directed against an epitope defined by the idio-peptide LCD-2, derived from 3H1. In vivo lymphocyte depletion experiments demonstrated that induction of CTL response and antitumour immunity was dependent on both CD4+ and CD8+ T cells. The analysis of splenocytes of immunized mice that had rejected C15 tumour growth revealed up-regulated surface expression of memory phenotype Ly-6C and CD44 on both CD4+ and CD8+ T cells. The adoptive transfer experiments also suggested the role of both CD4+ and CD8+ T cells in this model system. Furthermore, mice that had rejected C15 tumour growth, developed tumour-specific immunological memory.     

TH细胞在记忆性CTL介导的肿瘤抑制中的作用研究

目的 观察记忆性CTL的抑瘤作用是否需要抗原特异性TH细胞的辅助。方法 表达OVAT细胞表位SIINFEKL特异性TCR的T细胞转输RAG^-l-小鼠，经相应T细胞表位多肽刺激后产生记忆性CTL，将此记忆性CTL转输已产生特异性和非特异性TH细胞的C57BL／6小鼠体内并接种肿瘤细胞EG7。结果 经T细胞表位多肽免疫后，SIINFEKL特异性TCR T细胞成功在RAG^-l-小鼠体内增殖并分化为记忆性CTL；抗原特异性TH细胞可辅助产生较多效应性CTL但并没有完全的肿瘤抑制作用；记忆性CTL的完全抑瘤活性需要抗原特异性TH细胞的辅助。结论机体对肿瘤的长期完全杀伤作用不但需要肿瘤特异性抗原诱导产生的记忆性CTL，而且需要特异性TH细胞的辅助，肿瘤疫苗的设计必须包括特异性的CTL表位多肽和辅助性TH细胞多肽。     

Limitations of HLA-transgenic mice in presentation of HLA-restricted cytotoxic T-cell epitopes from endogenously processed human papillomavirus type 16 E7 protein

We investigated the use of mice transgenic for human leucocyte antigen (HLA) A*0201 antigen-binding domains to test vaccines composed of defined HLA A*0201-restricted cytotoxic T-lymphocyte (CTL) epitopes of human papillomavirus (HPV) type 16 E7 oncoprotein. HPV is detected in >90% of cervical carcinomas. HPV16 E7 oncoprotein transforms cells of the uterine cervix and functions as a tumour-associated antigen to which immunotherapeutic strategies may be directed. We report that although the HLA A*0201 E7 epitope peptides function both to prime for E7 CTL responses, and to sensitize target cells for E7-directed CTL killing in situations where antigen processing is not required, the epitopes are not processed out of either endogenously expressed or immunization-introduced E7, by the mouse antigen-processing and presentation machinery. Thus (1) CTL induced by HLA A*0201 peptide immunization killed E7 peptide-pulsed target cells, but did not kill target cells expressing whole E7; (2) immunization with whole E7 protein did not elicit CTL directed to HLA A*0201-restricted E7 CTL epitopes; (3) HLA A*0201-restricted CTL epitopes expressed in the context of a DNA polytope vaccine did not activate E7-specific T cells either in 'conventional' HLA A*0201 transgenic (A2.1Kb) mice, or in HHD transgenic mice in which expression of endogenous H-2 class 1 is precluded; and (4) HLA A*0201 E7 peptide epitope immunization was incapable of preventing the growth of an HLA A*0201- and E7-expressing tumour. There are generic implications for the universal applicability of HLA-class 1 transgenic mice for studies of human CTL epitope presentation in murine models of human infectious disease where recognition of endogenously processed antigen is necessary. There are also specific implications for the use of HLA A2 transgenic mice for the development of E7-based therapeutic vaccines for cervical cancer.