中国人CTLA—4基因的PCR—SSCP和DNA序列分析

ＣＴＬＡ－４是主要表达于成熟Ｔ细胞表面的蛋白分子，与Ｔ细胞参与的免疫应答负调控有关，目前有关ＣＴＬＡ－４的分子生物学资料多为外国提供，为了掌握中国人ＣＴＡＬ－４基因的第一手资料，我们对５０例中国人（其中２５例为正常人，２５例为类风湿性关节炎患者）的ＣＴＬＡ－４基因Ｖ区进行了ＰＣＲ扩增，并对其中４例正常人进行了ＤＮＡ序列分析，结果显示中国人ＣＴＬＡ－４ Ｖ区的ＤＮＡ序列与国外报道有两个位点存在差异，     

MOLECULAR COLNING AND SEQUENCE ANALYSIS OF THE IMMUNOGLOBULIN LIGHT

获得抗体的可变区基因是由鼠源性ＭｃＡｂ制备重组抗体的前提，本实验合成 与轻链可变区ＦＲ１和ＦＲ４互补的通用引物，由分泌抗人Ｃ１－ＩＮＨＭｃＡｂ的杂交瘤Ｆ７细胞株提取总ＲＮＡ，经ＲＴ－ＯＰＣＲ扩增出Ｆ７ＶＬ的ｃＤＮＡ片段，并将其克隆入ｐＵＣ１８／１９测序载体，     

抗体轻链可变区基因真核表达框架及抗CD3鼠/人嵌合轻链基因的构建

利用抗乙肝表面抗原的单抗２Ｈ１的轻链可变区基因的一部分，以核酸定点突变法引入ＭｌｕＩ限制性内切酶识别位点，构建了含有启动子、前导肽序列以及剪接供体信号等真核表达元件和“ＥｃｏＲＶ－Ｍｌｕ Ｉ”外显子克隆“匣”的通用的抗体轻链可变区基因真核表达框架ｐＧＥＭ－ＬＰＣＲ。从分泌ＣＤ３单抗的杂交瘤细胞中提取基因组ＤＮＡ，通过ＰＣＲ扩增及序列分析证实获得了ＣＤ３单抗轻链可变区基因的外显子。将其克隆到ｐＧＥＭ－ＬＰＣＲ中，切下完整的真核转录单位，与带有人Ｋａｐｐａ链恒定区基因及选择标记基因的表达载体相连接，成功地构建了抗ＣＤ３鼠／人嵌合轻链基因。此表达框架可用于多种抗体轻链可变区基因外显子的克隆及其真核转录单位的制备，大大简化了基因工程抗体的研制。     

CTLA41Ig对丝裂原诱导的淋巴细胞反应的影响

本研究证明ＣＴＬＡ４Ｉｇ一Ｂ７分子结合后，可以阻断Ｂ７与ＣＤ２８的结合。ＣＴＬＡ４Ｉｇ可以掏丝黎明原所解发淋巴细胞的增殖反应，同时抑制细胞因子ＩＬ－２，ＩＬ－４的产生以及ＩＬ－２Ｒ的表达。表明ＣＴＬＡ４Ｉｇ可以通过不同的途径影响Ｔ淋巴细胞的活化。     

人血小板生成素cDNA转染COS-7细胞及表达产物对小鼠骨髓巨核细胞的作用

将克隆全长１．１ｋｂ血小板生成素（ＴＰＯ）ｃＤＮＡ构建重组ＰＣＩｎｅｏＴＰＯ表达载体，利用ＬｉｐｏｆｅｃｔｉｎＴＭ介导转染ＣＯＳ－７细胞中，对阳性克隆ＣＯＳ－７细胞的ＤＮＡ、ｍＲＮＡ和培养上清分别进行ＰＣＲ扩增Ｓｏｕｔｈｅｒｎｂｌｏｔ、斑点杂交和ＴＰＯ夹心ＥＬＩＳＡ检测，观察表达产物对小鼠骨髓巨核细胞的作用。结果表明：全长１．１ｋｂＴＰＯｃＤＮＡ转染ＣＯＳ－７细胞获得表达，最高表达量可达４８．２８Ｕ／ｍｌ，其产物使骨髓巨核细胞集落形成单位（ＣＦＵ－ＭＫ）集落数增加４倍，巨核细胞增大至４２．１０±６．７０μｍ（Ｐ＜０．０１）；动态观察骨髓ＣＦＵ－ＭＫ集落数于实验第８天达最高峰，约持续２ｄ，第１０天后开始下降。提示ＴＰＯｃＤＮＡ转染ＣＯＳ－７细胞表达产物对骨髓巨核细胞生成有刺激活性     

竞争性定量RT-PCR技术在t(8;21)AML微小残留病变检测中的应用

目的：建立针对ＡＭＬ－ＥＴＯ融合基因转录本的竞争性定量反向－聚合酶链反应（ＲＴ－ＰＣＲ）体系,并探讨其在ｔ（８;２１）急性髓细胞性白血病（ａｃｕｔｅ ｍｙｅｌｏｉｄ ｌｅｕｋｅｍｉａ,ＡＭＬ）微小残留病变跟踪中的应用价值。方法：采用重叠延伸剪接术（ｓｐｌｉｃｉｎｇ ｂｙ ｏｖｅｒｌａｐｐｉｎｇ ｅｘｔｅｎｔｉｏｎ,ＳＯＥ）获得竞争性ＤＮＡ片段,建立竞争性定量ＰＣＲ方法,并应用于ｔ（８;２１）ＡＭＬ患者的检测。结果：成功建立了竞争性定量ＰＣＲ方法〈并获得不同ｔ（８;２１）ＡＭＬ患者的ＡＭＬ１－ＥＴＯ融合基因转录本的竞争性定量ＰＣＲ结果。结论：以ＳＯＥ方法为基础的竞争性定量ＰＣＲ方法简单、适用;不同生存状态下的ｔ（８;２１）ＡＭＬ患者的ＡＭＬ１－ＥＴＯ融合基因转录本表达量具有明显差异。     

中国汉族乳腺癌中BRCA1基因的杂合性丢失和微卫星不稳定性

目的探讨中国汉族妇女乳腺癌与乳腺癌基因１的关系。方法对ＢＲＣＡ１区域内的４个微卫星多态位点，应用聚合酶链式反应（ＰＣＲ）－聚丙烯酰胺尿素凝胶电泳（ＰＡＵＧＥ）－ＤＮＡ银染方法，对上海市５０例乳腺癌患者进行了ＢＲＣＡ１有关微卫星的ＬＯＨ和ＭＳＩ研究。结果患者中ＬＯＨ的发生率为５８％，ＭＳＩ的发生率为４６％；对患者进行临床分组，发现病期越晚ＬＯＨ率越高，ＭＳＩ与临床分期的关系不很确定。结论提示中国汉族人的乳腺癌的发生同与ＢＲＣＡ１基因相连锁的微卫星ＤＮＡ有关，因而也可能与ＢＲＣＡ１基因的突变有关。     

抗体轻链可变区基因真核表达框架及抗CD3鼠／人嵌合…

利用抗乙肝表面抗原的单抗２Ｈ１的轻链可变区基因的一部分，以核酸定点突变法引入ＭｌｕＩ限制性内切酶识别位点，构建了含有启动子、前导肽序列以及剪接共体信号等真核表达元件和“ＥｃｏＲＶ－ＭｌｕＩ”外显子克隆“匣”的通用的抗体轻链可变区基因真核表达框架ｐＧＥＭ－ＬＰＣＲ。从分泌ＣＤ８单抗的杂交瘤细胞中提取基因组ＤＮＡ，通过ＰＣＲ扩增及序列分析证实获得了ＣＤ３单抗轻链可变区基因的外显子。将其克隆到ｐＧＥＭ－     

利用基因扫描分析TCR Vβ亚家族的CDR3长度方法检测T细胞克隆性

分析了健康人、Ｔ－ＡＬＬ外周血及Ｔ细胞株Ｍｏｌｔ－４和Ｊｕｒｋａｔ中ＴＣＲＶβＴ细胞的表达和克隆性。应用ＲＴ－ＰＣＲ扩增ＴＣＲＶβ２４个亚家族的ＣＤＲ３，并经基因扫描和序列分析确定Ｔ细胞克隆性。结果表明健康人表达除Ｖβ２０外的多克隆Ｔ细胞；Ｔ－ＡＬＬ仅表达３～４个Ｖβ亚家族Ｔ细胞；部分呈寡克隆性；Ｍｏｌｔ－４和Ｊｕｒｋａｔ分别表达Ｖβ２和Ｖβ８单克隆Ｔ细胞。Ｔ－ＡＬＬ中存在克隆性生长Ｔ细胞。该方法是检测Ｔ细胞克隆性的敏感和精确的方法。     

慢性髓系白血病bcr—abl融合基因的克隆及其在COS …

目的 克隆慢性髓系白血病（ＣＭＬ）融合基因ｂｃｒ－ａｂｌ的ｃＤＮＡ序列,并在真核细胞中表达。方法 以设计的两条引物扩增ｂｃｒ－ａｂｌ融合位点两侧的ｃＤＮＡ,测序后克隆至真核表达载体ｐｃＤＮＡ３．１,转染ＣＯＳ－７细胞。取常规培养的细胞进行ＲＴ－ＰＣＲ鉴定。结果 ①ＰＣＲ扩增出４９０ｂｐ大小的ｃＤＮＡ,其序列测定除第４５２位的碱基Ｃ突变为Ｔ外,其余序列均正确。②ＲＴ－ＰＣＲ法检测到转染细胞系中,有ｂ     

GPI-CTLA4Ig嵌合分子的构建和在CHO-dhfr-细胞膜上的表达

目的：研制GPI锚定修饰的新型免疫抑制分子GPI—CTLA4Ig。方法：通过将从促衰变因子(DAF)来源的GPI修饰性信号序列与CTLA4Ig嵌合，获得CPI修饰的CTLA4Ig分子。将编码GPI—CTLA4Ig嵌合分子的基因克隆到真核表达载体pCI—dhfr中，并用脂质体法转染CHO—dhfr^-细胞，用氨甲喋呤(MTX)进行筛选。重组蛋白的表达用RT—PCR、ELISA、细胞免疫荧光和Western blot进行鉴定。最后采用Protein A亲和层析纯化。结果：构建了GPI—CTLA4Ig嵌合分子，并在CHO—dhfr^-细胞膜上稳定表达。结论：GPI修饰的CTLA4Ig分子有可能作为新型的免疫抑制剂用于器官移植中，抑制移植排斥反应。     

腺病毒介导CTLA4Ig基因修饰骨髓间质干细胞体外抑制免疫应答的研究

目的:通过腺病毒载体介导CTLA4Ig在大鼠骨髓间质干细胞(MSC)中的表达,探讨MSC作为基因转移靶细胞的可行性和转染效率,研究其在体外对免疫应答的抑制作用。方法:构建含有CTLA4Ig基因的重组腺病毒载体pAd-CTLA4Ig,按照不同的感染倍率(MOI)转染大鼠MSC,用荧光显微镜和流式细胞仪分析转染效率,流式细胞术、Westernblotting等方法检测目的蛋白CTLA4Ig在MSC中的表达。将转基因MSC加入混合淋巴细胞反应(MLR)体系,观察其抑制淋巴细胞增殖的生物学效应。结果:重组腺病毒载体pAd-CTLA4Ig对MSC的最大转染率为80.7%±4.7%,转基因MSC可检测到目的蛋白的表达。基因修饰的MSC能有效抑制MLR体系中淋巴细胞的增殖,4d达到最大抑制效率51.46％;再次MLR证实这种抑制作用是供者特异性的。结论:MSC是一种较理想的基因转移靶细胞,其表达的转基因产物CTLA4Ig可在体外特异性地抑制免疫应答。     

核小体Th表位和CTLA4Ig双基因共表达真核表达载体的构建

目的将核小体Th表位与CTLA4Ig融合基因融合，研究CTLA4Ig作为真核表达载体的可行性。方法用touchdown PCR法扩增CTLA4Ig基因，同时引入核小体Th表位（H2B14-28）。将PCR产物连接真核表达载体pcDNA3．1（＋），构建pcDNA3．1（＋）-CTLA4Ig—H2B。将表达质粒转染COS-7细胞，Western blot检测转染细胞裂解上清中融合蛋白的表达。将构建表达CTLA4Ig—H2B的减毒鼠伤寒沙门氏菌SL7207喂饲BALB／c小鼠，取脾脏进行免疫组化鉴定重组蛋白在动物体内的表达。结果酶切鉴定和基因序列测定显示重组质粒构建成功。在pcDNA3．1（＋）-CTLA4Ig—H2B质粒转染后48h细胞裂解上清中，检测到CTLA4Ig融合蛋白的表达，该蛋白能与抗人CTLA-4单抗特异结合。重组蛋白在BALB／c小鼠脾脏免疫细胞胞浆中有阳性表达。结论成功构建了能稳定表达核小体Th表位和CTLA4Ig融合基因的真核表达载体。     

Differential inhibition of autoreactive memory- and alloreactive naive T cell responses by soluble cytotoxic T lymphocyte antigen 4 (sCTLA4), CTLA4Ig and LEA29Y

Cytotoxic T lymphocyte antigen 4 (CTLA4) is a potent inhibitory co-stimulatory molecule believed to be involved in type 1 diabetes and other autoimmune diseases. An association has been reported of both mRNA expression and serum levels of the soluble splice variant of CTLA4 (sCTLA4) with type 1 diabetes. Furthermore, recombinant fusion proteins CTLA4Ig and LEA29Y have been proposed as therapies for type 1 diabetes. We studied the role of (s)CTLA4 in islet autoimmunity. Binding capacity of the proteins to antigen-presenting cells was determined by flow cytometry in competition and binding assays. Functionality of sCTLA4 as well as the therapeutic inhibitory fusion proteins CTLA4Ig and LEA29Y was measured in a dose-response lymphocyte stimulation test, using a panel of diabetes-associated T cell clones reactive to islet autoantigens. As controls, mixed lymphocyte reactions (MLR) were performed to assess functionality of these proteins in a primary alloreactive setting. All three CTLA4 molecules were able to bind to antigen-presenting cells and inhibit the expression of CD80/CD86. sCTLA4 was able to suppress proliferation of different committed autoreactive T cell clones in a dose-dependent manner, whereas CTLA4Ig and LEA29Y were not. Conversely, CTLA4Ig and LEA29Y, rather than sCTLA4, were able to suppress naive alloreactive proliferation in a MLR. Our results indicate a differential role for sCTLA4, CTLA4Ig and LEA29Y proteins in memory versus primary immune responses with implications for efficacy in intervention therapy.     

抗人CTLA-4单克隆抗体的制备及其生物学活性研究

以我室用基因工程表达的人CTLA 4蛋白[1,2 ] 作为免疫原 ,采用细胞融合、ELISA法和免疫印迹等方法制备并筛选到鼠抗人CTLA 4的单克隆抗体 ,并以单向混合淋巴细胞刺激反应 (MLR )测定了抗人CTLA 4抗体对淋巴细胞增殖的影响。结果表明我们得到了 4株单克隆抗体 (1H7、 2G2、 2F11、 3A7) ,它们均可与近似天然构象的人CTLA 4Ig融合蛋白结合 ,又可与大肠杆菌表达出的经复性后的人CTLA 4蛋白结合 ,并且可分别识别人CTLA 4Ig融合蛋白不同抗原决定簇。其中一株(3A7)既和近似天然构象的蛋白结合又可与变性的蛋白结合 ,并具有显著阻断CTLA 4的抑制性免疫信号传递 ,促进同种异体混合淋巴细胞增殖的功能     

CTLA4-EGFP融合蛋白在K562细胞中的表达及其亚细胞定位研究

目的 :构建增强型绿色荧光蛋白 (EGFP)与CTLA4融合蛋白真核表达载体 ,分析其在K562细胞中的表达和亚细胞定位。方法 :以RT PCR方法克隆人CTLA4基因 ,构建CTLA4 EGFP融合蛋白的表达载体。以其转染K562细胞后 ,以流式细胞仪和激光共聚焦显微镜分析融合蛋白的表达及其亚细胞定位。结果 :从人外周血细胞中克隆到CTLA4基因的cDNA。通过PCR方法在起始位点前加入Kozak序列并删除终止密码 ,成功地构建CTLA4 EGFP融合蛋白表达载体。以该质粒转染K562细胞 2 4h后 ,CTLA4和EGFP双阳性细胞的百分率为 16%。表达的融合蛋白主要分布于胞内 ,细胞膜上分布较少。相反 ,转染空载体的细胞仅表达EGFP ,且其在细胞内呈弥散样分布。以佛波醇酯加离子霉素刺激后 ,CTLA4 EGFP融合蛋白在细胞表面表达水平升高到 2 9% ,且分布于胞内的融合蛋白向细胞膜靠近并与质膜融合 ;而转染空载体的细胞内EGFP的分布无明显改变。结论 :成功地构建CTLA4 EGFP融合蛋白表达载体 ,并在K562细胞中得到表达。表达的融合蛋白与天然CTLA4在活化T细胞中的定位和转运特点相似     

Local gene therapy with CTLA4-immunoglobulin fusion protein in experimental allergic encephalomyelitis

It has been reported previously that the induction phase of experimental allergic encephalomyelitis (EAE) is highly sensitive to systemic blockade of stimulation via MHC class II molecules and co-stimulation via the CD28 : CD80/CD86 pathways. In contrast, the effector phases of EAE were relatively unaffected by similar treatments using MHC class II antigen (Ag)-specific mAb and cytotoxic T lymphocyte antigen (CTLA)4-Ig fusion proteins in some studies. This has been attributed to different sensitivities of effector cell function or the poor penetrance of inhibitory proteins into the central nervous system (CNS). To examine this question further, MHC class II Ag-specific mAb and CTLA4-Ig were delivered directly into the CNS following EAE induction, and both were found to inhibit disease. While it was found that systemic administration of mouse CTLA4-Ig could also inhibit the progression of effector immune responses when administered shortly before or during clinical disease, these were significantly more active when delivered directly into the CNS, which probably involved an action on both CD28 ligands, CD80 and CD86. Although mouse CTLA4-human Ig was therapeutically less efficient than mouse CTLA4-mouse Ig protein, probably due to the enhanced immunogenicity and lower functional activity, gene delivery of CTLA4-human Ig into the CNS using a non-replicating adenoviral vector was more effective than a single injection of CTLA4-human Ig protein. Gene delivery significantly ameliorated the development of EAE, without necessarily inhibiting unrelated peripheral immune responsiveness. Local gene delivery of CTLA4-Ig may thus be an important target for immunotherapy of human autoimmune conditions such as multiple sclerosis.     

CTLA4Ig Primed Donor Lymphocyte Infusion: A Novel Approach to Immunotherapy after Haploidentical Transplantation for Advanced Leukemia

CTLA4Ig attenuates T cell activation by co-stimulation blockade, but natural killer (NK) cells are not only resistant to CTLA4Ig, they also may demonstrate better antileukemia effect in the presence of CTLA4Ig. To explore this phenomenon we used sequential CTLA4Ig primed donor lymphocyte infusion (DLI) after post-transplant cyclophosphamide–based haploidentical transplantation. Thirty patients (CTLA4Ig-DLI group) with advanced leukemia received CTLA4Ig on day –1 and subsequently on days +7, +21, and +35, followed 12hours later by DLI of 1 to 10?×?10⁶ CD3⁺ T cells/kg containing .1 to 3.27?×?10⁶/kg CD56⁺ NK cells, with low dose cyclosporine for 60days. The incidences of acute graft-versus-host disease (GVHD), chronic GVHD and nonrelapse mortality (NRM) were 6.7%, 21%, and 4.5 %, respectively, with disease progression of 23.3% and overall survival of 79% at 18 months. Patients without disease progression had a significant early surge in CD56^dimCD16⁺NK cells with lower NKG2A expression. CTLA4Ig primed DLI was associated with an upregulation of CD86 in mature NK cells that was not witnessed with CTLA4Ig administration alone. Thus, CTLA4Ig primed DLI resulted in early proliferation of mature NK cells with cytotoxic potential enabling early institution of adoptive immunotherapy to mitigate the risk of relapse in advanced leukemia with reduced GVHD and NRM.     

CTLA4Ig基因修饰BMSCs对异种胰岛移植排斥反应的影响

目的 探讨细胞毒性T淋巴细胞相关抗原4免疫球蛋白( CTLA4Ig)基因修饰骨髓间充质干细胞(BMSCs)在异种胰岛移植排斥反应中的作用.方法 构建携带CTLA4Ig基因的重组腺病毒载体,用其感染BMSCs并和人胰岛细胞移植到糖尿病大鼠肾包膜下,建立人-大鼠异种胰岛移植模型.观察胰岛移植后糖尿病大鼠血糖变化、生存情况以...     

CTLA-4Ig治疗作用的实验研究进展

控制器官移植后的排斥反应以及治疗风湿性关节炎之类的自身免疫性疾病一直是医学科学领域的难题.传统采用一些非特异的免疫抑制剂比如激素、环孢霉素进行治疗,其作用有限,而且会导致全身感染、肿瘤发生等副作用.CTLA-4Ig是人CTLA-4分子胞外区与人免疫球蛋白γ1绞链区、CH2、CH3区组成的融合蛋白,与B7有高度的亲和力,可以阻断B7与CD28的结合.它不但可以封闭B7,导致免疫耐受,而且可以调节免疫细胞的分化,调节免疫反应.因而,作为一种人类基因工程生物制剂,它在抗移植排斥反应、治疗自身免疫性疾病等方面具有重要的应用价值,而且不会损害免疫系统的功能.