小细胞肺癌抗独特型单链抗体的表达及活性研究

目的:在大肠杆菌中高效表达小细胞肺癌(SCLC)抗独特型抗体3F6单链抗体(ScFv),并获得具有生物学活性的ScFv。方法:从SCLC抗独特型抗体3F6小鼠杂交瘤细胞中提取总RNA,反转录为cDNA。利用小鼠抗体骨架区共用引物,PCR扩增单抗重链可变区(VH)和轻链可变区(VL)。通过人工设计的柔性连接肽(Gly4Ser)3连接构建3F6ScFv。再将其重组到原核表达载体pQE31中,构建3F6ScFv表达载体。转化大肠杆菌M15,IPTG诱导表达,用NiNTA树脂对表达产物进行变性纯化。通过凝胶(SephacrylS200)柱上在位复性后,用竞争ELISA检测复性的3F6ScFv活性。结果:获得了SCLC抗独特型抗体3F6的VH和VL基因,构建了3F6ScFv表达质粒。在大肠杆菌中高效表达3F6ScFv,表达蛋白的相对分子质量为32×103,以包涵体形式存在。纯化后获得较纯的3F6ScFv蛋白,经复性后可竞争2F7抗体与SCLCNIHH128细胞结合。结论:成功构建、表达、纯化和复性了SCLC抗独特型抗体3F6ScFv,获得有活性的3F6ScFv,为SCLC抗独特型抗体的进一步研究奠定了基础。     

卵巢癌抗独特型微抗体疫苗诱导BALB/c小鼠体内抗肿瘤免疫应答的实验研究

背景与目的：6B11抗独特型微抗体由模拟人卵巢癌抗原的抗独特型单链抗体(6B11ScFv)融合人IgG1铰链区和CH3区所构成,它具有6811ScFv和人1gGFc的双重免疫学活性。本研究观察6811抗独特型微抗体在BALB／c小鼠体内诱导抗肿瘤免疫反应情况,探讨其作为卵巢癌疫苗的可能性。方法：用卵巢癌6B11抗独特型微抗体免疫BALB／c小鼠。采用间接ELISA、竞争抑制实验和流式细胞术检测免疫鼠血清。结果：6B11抗独特型微抗体免疫小鼠后,在不用佐剂的情况下可诱导小鼠产生较高的Ab3,末次免疫后30天仍持续在较高的水平。分别在末次免疫后4天、14天、24天和30天可刺激小鼠脾脏淋巴细胞CD4^ T细胞和CD8^ T细胞明显升高。结论：6811抗独特型微抗体可诱导机体产生特异体液免疫和细胞免疫反应,这为抗独特型微抗体疫苗的临床应用提供了一定的实验依据。     

107. 体外致敏鼻咽癌患者B细胞构建抗独特型噬菌体抗体库

根据Jerne免疫网络理论,抗独持型抗体（Ab2β）在三维空间能够模拟Ab1所识别的抗原结构,可以替代肿瘤抗原作为抗肿瘤疫苗,激发机体体液免疫和细胞免疫应答。抗独特型抗体的这种分子模拟功能在肿瘤免疫治疗领域已展示出诱人的前景。但因杂交瘤技术制备的单克隆抗独特型抗体为鼠源性抗体,临床应用受到极大的限制。为解决这一难题,本实验采用体外致敏法结合噬菌体呈现技术构建鼻咽癌抗独特型噬菌体抗体库。以本室制备的抗鼻咽癌单抗FC2（Ab1）为免疫原,体外致敏并用EBV转化10例鼻咽癌患者PBMC,经Sandwich ELISA检测其中8例有Ab2产生。抽提致敏、转化的鼻咽癌患者B细胞的总RNA,用cDNA合成试剂盒反转录为cDNA,经多次PCR扩增出5种VH（γ、μ)和9种VL（κ、λ）基因,经简并组成15种ScFv基因,在体外与载体fuse5连接,电导入大肠杆菌MC1061,经四环素抗性筛选,得到库容为1．1×107的初级噬菌体抗体库。随机挑取20个菌落检查噬菌体DNA中全长ScFv基因的插入率为70％。这不仅为进一步用抗鼻咽癌单抗亲和筛选具有内影像特点的抗独特型单链抗体（Ab2βScFv）奠定了基础,而且说明外致敏法结合噬菌体抗体库技术制备人源化Ab2βScFv的策略是完全可行的。     

卵巢癌抗独特型单链抗体6B11ScFv/鼠GMCSF融合蛋白(6B11mGM)的构建、表达和特性研究

抗独特型抗体能够模拟肿瘤抗原,调节机体免疫功能,已成为肿瘤免疫治疗研究中一个十分重要的研究领域.本中心制备的卵巢癌抗独特型抗体6B11能模拟卵巢癌抗原诱导特异性抗肿瘤免疫应答.为降低鼠源性单抗进入体内引起的不良免疫反应,本中心已成功制备了基因工程抗独特型单链抗体(6B11ScFv).为了增加6B11ScFv的免疫原性,又构建了6B11ScFv与人GM-CSF融合蛋白(6B11GM).但由于缺     

鼻咽癌抗独特型单克隆抗体的主动免疫初探

用湖南鼻咽癌细胞株HNI2为免疫原,制备了数株抗鼻咽癌单抗(Abl).再用两株Abl(FC_2、HNI-5)为免疫原,制备了两株抗独特型单抗Ab2(2H4和5D3).体外和体内实验证实,2H4、5D3能替代鼻咽癌抗原,诱导体液和细胞免疫应答.因而认为它们可以作为新型抗鼻咽癌疫苗的候选物.选择19例晚期鼻咽癌病人用氢氧化铝凝胶沉淀的Ab2(Alum-2H4、Alum5D3),配合放疗进行主动免疫治疗;9例单纯接受放疗的晚期鼻咽癌病人作为对照组.经血清学检测发现,治疗组病人的抗抗独特型抗体(Ab3)、抗肿瘤抗体(Ab1’)水平均有不同程度增高,但也产生了人抗鼠抗体(HAMA).血清细胞因子TNF-α、IFN-γ、IL-2水平在大多数治疗组病人中升高,而对照组Ab1 TNF-α、IFN-γIFM及IL-2血清水平均未升高.初步临床研究显示,鼠源性抗独特型单抗用于临床治疗是安全的,且Ab2能模拟肿瘤相关抗原,激发机体产生主动免疫应答.     

抗独特型抗体与肿瘤免疫治疗

抗独特型抗体的应用是近年来肿瘤免疫治疗的一种新方法，抗独特型抗体由特异性抗体Ab1诱导产生，具有替代抗原作用，能诱导机体产生特异性的免疫应答。大量的动物实验和临床资料表明，肿瘤特异性独特型瘤苗具有较多的优点和较强的抗瘤作用。本文对其产生特异免疫反应和抗瘤作用的机制进行了探讨，并根据国外最新研究动态，综述了独特型抗体在主动免疫治疗方面的实验资料及对几种肿瘤的治疗价值。     

抗独特型抗体对肿瘤的免疫治疗

1974年Jerne提出网络学说以来,对独特型(Id)、抗独特型(A-Id)、抗抗独特型调节网络进行了大量的研究,其中最受关注的是处于正负调节枢纽的Id环节,Id亦为抗原决定簇,为V基因编码的抗体和TCR表型.根据这一学说认为外在抗原为抗体中Id和T细胞受体所模仿,抗原注射于机体所产生的抗体为Ab1,而Ab1本身具有免疫原性产生A-Id抗体(Ab2),有一部分Ab2在三度空间模仿外在抗原,称     

鼻咽癌人源抗独特型单链抗体的制备及筛选

背景与目的:抗独特型抗体作为肿瘤抗原替代物可用于肿瘤治疗,这已在临床试验中得到证实。但由于目前所使用的抗独特型抗体多为鼠源性,用于人体可产生人抗鼠抗体反应,从而影响疗效。本实验拟构建噬菌体人源抗独特型抗体库,并从中筛选出能模拟鼻咽癌相关抗原的β型抗独特型单链抗体scFv(Ab2βscFv),以解决鼠源性抗独特型抗体用于临床所产生的人抗鼠抗体反应。方法:体外致敏并用EB病毒(Epstein-Barrvirus,EBV)转化鼻咽癌患者的外周血单个核细胞(peripheralbloodmononuclearcell,PBMC),用RT-PCR分别扩增VH和VL基因并连接成scFv基因,将scFv基因与载体fUSE5连接后,转化大肠杆菌MC1061,构建噬菌体呈现型scFv库。在用单抗FC2对文库进行4轮筛选后,用SandwichELISA和结合抑制法从中筛选出β型Ab2scFv。结果:用单抗FC2体外致敏并经EBV转化的10例鼻咽癌患者的PBMC中,8例有鼻咽癌抗独特型抗体产生。经PCR分别扩增出5种VH(γ、μ)和7种VL(κ、λ)基因,经连接组成14种scFv基因。在与载体连接后,导入大肠杆菌MC1061,得到库容为1.5×108的初级噬菌体抗独特型抗体库。经富集筛选后,从中随机挑取270个克隆进行ELISA筛选,得到91个Ab2scFv单克隆,阳性率为33.7%。再用结合抑制法从中初步筛选出5个可能为β型的Ab2scFv。结论:联     

HER2抗独特型单克隆抗体的制备和初步研究

目的:研制HER2抗独特型单克隆抗体,为进一步深入研究乳腺癌抗独特型抗体疫苗奠定基础。方法:用人HER2蛋白免疫家兔,获得特异性兔抗HER2抗体。再用兔抗HER2抗体免疫Balb/c小鼠,采用杂交瘤技术制备HER2抗独特型单克隆抗体。并筛选出β型HER2抗独特型单克隆抗体。结果:ELISA检测结果表明,获得的兔抗HER2抗体能特异性地与HER2蛋白结合,其OD值随HER2的浓度呈正线性关系。用兔抗HER2抗体免疫小鼠获得一株稳定分泌HER2抗独特型单克隆抗体的杂交瘤细胞1F5,其分泌的单克隆抗体能特异性的和兔抗HER2多克隆抗体结合,并与HER2产生竞争抑制作用。用1F5抗独特型单克隆抗体免疫家兔得到的抗血清能和HER2特异性的结合。该抗体亚型为IgG3,未浓缩腹水的效价为1∶1.02×104。结论:抗独特型单克隆抗体为β型HER2抗独特型抗体,有可能成为乳腺癌抗独特型单克隆抗体疫苗。     

用抗独特型疫苗主动免疫增强鼻咽癌病人的IL-2mRNA表达

用两株具有鼻咽癌相关抗原内影像的抗独特型单克隆抗体2H4,5D3,经氢氧化铝凝胶沉淀法制备成抗独特型疫苗Alum-2H4,Alum-5D3,对19例晚期鼻咽癌放疗病人作主动免疫治疗,9例放疗加生理盐水注射为对照组.用ELISA检测治疗前后病人血清抗体和细胞因子水平.用原位Northem杂交检测外周血单个核细胞(PBMC)IL-2mRNA的表达.发现接受Alum-2H4或Alum-5D3治疗的病人无1例有过敏或其他毒副反应,血清中均检测到抗抗独特型抗体(Ab3)、抗肿瘤抗体(Ab1’)水平均有不同程度的增高,但也产生了人抗鼠抗体(HAMA).血清细胞因子TNF-α,IFN-γ和IL-2水平在大多     

Tumor-antigen-specific humoral immune response of animals to anti-idiotypic antibodies and comparative serological analysis of patients with small-cell lung carcinoma.

We have previously developed 3 monoclonal anti-idiotypic antibodies (Ab2) of LOU rat origin directed against the binding site of the murine monoclonal IgM LAM8, which recognizes the small-cell lung carcinoma (SCLC)-associated sialoglycoprotein antigen sGP 90-135. The aim of this study was to compare the efficiencies of these 3 Ab2, designated LY8-229, LX8-531 and LX8-632, to induce antigen-specific immunity in different animal species without prior exposure of the recipients to the nominal antigen, and thereby possibly select an Ab2 candidate for active immunotherapy against SCLC in patients. The feasibility of this approach was further evaluated by a serological analysis of patients with SCLC compared with healthy individuals, in whom the spontaneous antibody reactivities against SCLC cell lines and Ab2 were tested. LY8-229 was shown to be the most effective Ab2 in inducing antigen-specific antibodies in BALB/c mice, CBA/J/Zur mice and one NZW rabbit. Furthermore, LY8-229 was the only Ab2 against which significantly elevated idiotype-specific antibody reactivities existed in sera of patients with SCLC. These reactivities correlated positively with binding to antigen-positive tumor cells. Our findings suggest that LY8-229 represents in its reactivity pattern the nominal SCLC antigen in humans also, and therefore may be of diagnostic and possibly therapeutic relevance for patients with SCLC.     

Monoclonal anti-idiotype antibody 6G6.C4 fused to GM-CSF is capable of breaking tolerance to carcinoembryonic antigen (CEA) in CEA-transgenic mice

Internal image anti-idiotypic antibodies are capable of mimicking tumor-associated antigens and thus may serve as surrogate for vaccination strategies in cancer patients. The monoclonal antibody (mAb) 6G6.C4 mimics an epitope specific for the human carcinoembryonic antigen (CEA) and generates a CEA-specific response (Ab3) in various experimental animals. In humans, however, 6G6.C4 only yields a very limited humoral anti-CEA reaction presumably due to tolerance against the CEA autoantigen. In this study, we investigated the CEA-specific Ab3 response in mice transgenic for the human CEA and tested whether the antigen tolerance could be overcome by fusing a recombinant single-chain variable fragment of 6G6.C4 (scFv6G6.C4) to the murine granulocyte macrophage colony-stimulating factor (GM-CSF).Like mAb 6G6.C4, the fusion protein (scFv6G6.C4/GM-CSF) retained binding to the CEA-specific idiotype mAb T84.66. Also, scFv6G6.C4/GM-CSF was biologically active as measured by proliferation of the GM-CSF-dependent murine FDC-P1 cells in vitro. After immunization with the scFv6G6.C4/GM-CSF fusion protein, CEA-transgenic animals showed significantly enhanced Ab3 antibody responses to scFv6G6.C4 (P=0.005) and to CEA (P=0.012) compared with the scFV6G6.C4 alone. Sera from mice immunized with the fusion protein specifically recognized CEA in Western blot analyses with no cross-reaction to CEA-related antigens. Finally, the Ab3 antisera detected single CEA-expressing tumor cells in suspension as shown by flow cytometry. Taken together, these data show in a model antigenically related to the human system that vaccination with scFv6G6.C4/GM-CSF improves vaccination against an endogenous tumor-associated antigen resulting in a highly specific humoral Ab3 response in vivo that is capable of bind single circulating CEA-positive tumor cells.     

小细胞肺癌2F7单抗ScFv的高效表达及复性研究

目的 在大肠杆菌中高效表达小细胞肺癌单抗2F7的单链抗体（ScFv)，并获得具有生物学活性的ScFv。方法 利用PCR方法将2F7单抗重链可变区（VH）和轻链可变区（VL）通过一人工设计的柔性连接肽（Linker)连接，再将单链抗体基因重组到原核表达载体pQE31中，构建单链抗体高效表达载体pQE-2F7-ScFv。将pQE-2F7-ScFv质粒转化大肠杆菌M15后诱导表达，并对表达产物进行纯化和稀释复性。结果 获得了2F7单链抗体的高效表达，表达蛋白大小约27.4kD，以包涵体形式存在。包涵体蛋白在经过变性、纯化和稀释复性后，获得了有功能的单链抗体。结论 成功地构建和表达了小细胞肺癌单抗F27的单链抗体，并对其进行了纯化和复性，将进一步促进2F7单抗小分子抗体的应用。     

Monoclonal anti-idiotypic antibody functionally mimics the human gastrointestinal carcinoma epitope GA733

Anti-idiotypic antibodies (Ab2) that bind to the antigen-combining region of anti-tumor antibodies (Ab1) may functionally, and even structurally, mimic tumor antigen. We have previously demonstrated that polyclonal goat Ab2 directed against anti-human gastrointestinal carcinoma Ab1 GA733 induces anti-anti-idiotypic antibodies (Ab3) in animals that are Ab1-like in their binding specificity and idiotope expression. To obtain more defined Ab2 vaccines with potentially increased specificity and efficacy, a monoclonal Ab2 (FG1) was produced against Ab1 GA733 in rats. The monoclonal Ab2 FG1, similar to the polyclonal Ab2 described previously, induced Ab3 in rabbits that were Ab1-like in their idiotope expression and binding specificity to tumor cells and antigen. Antigen-specific Ab3 induced by Ab2 FG1 were easily detected in unprocessed rabbit sera, whereas the demonstration of such Ab3 after polyclonal Ab2 immunization required purification of the Ab3 from the rabbit sera. In addition, Ab2 FG1 induced antigen-specific humoral and cellular immunity in mice. Murine Ab3 bound specifically to antigen-positive tumor cells. Ab2-immunized mice showed antigen-specific delayed-type hypersensitivity (DTH) reaction, and cultured splenocytes from the immune mice demonstrated specific proliferation and cytokine (interferon-γ and interleukin-4) secretion upon stimulation with GA733 antigen. However, immune mice were not protected against a challenge with syngeneic GA733 antigen-expressing colon carcinoma cells. © 1996 Wiley-Liss, Inc.     

Characterization of two human small cell lung carcinoma-reactive monoclonal antibodies generated by a novel immunization approach

Two human small cell lung carcinoma cell lines, NCI-H69 and NCI-H128, were used as alternating sources of immunogen to generate monoclonal antibodies to small cell lung carcinoma-associated antigens. BALB/c mice were sensitized with seven injections of live tumor cells, four with NCI-H69 cells and three with NCI-H128 cells. Somatic cell hybridization was performed by fusion of the immune murine splenocytes using syngeneic myeloma cells from the SP2/0 Ag14 cell line. Hybridoma colonies were screened against small cell lung carcinoma cells and normal lung fibroblasts with an enzyme-linked immunosorbent assay. Compared to animals immunized with only NCI-H69 or NCI-H128 cells, alternate immunization resulted in the generation of a significantly higher number of hybridomas that reacted selectively with both tumor cell lines. Monoclonal antibodies from two reactive hybrid clones generated by alternate immunization, SCLC 2051 and SCLC 5023, were uniformly negative to normal human tissues including lung, kidney, liver, spleen, breast, thyroid, brain, small intestine, and colon. While both monoclonal antibodies were nonreactive to paraffin-embedded, formalin-fixed, nonmalignant lung biopsies, the monoclonal antibody SCLC 5023 reacted with tumor cell infiltrates in biopsies from small cell lung carcinoma patients (14 of 14 cases positive), using the immunoperoxidase technique. This monoclonal reagent also reacted with other lung tumor cell types, including atypical carcinoid (5 of 5 positive), epidermoid (4 of 6 positive), undifferentiated and bronchoalveolar (3 of 4 cases each positive) carcinomas. By contrast, monoclonal antibody SCLC 2051 apparently identified an antigen expressed preferentially on small cell lung carcinoma cells (12 of 14 positive) and only rarely reacted with other lung tumor cell types (2 of 34 positive). Both monoclonal antibodies were negative to colon carcinoma, epidermoid carcinoma of the floor of the mouth, breast adenocarcinoma, and B- and T-cell leukemia and lymphoma cells, as determined by the enzyme-linked immunosorbent assay, indirect immunofluorescence, and immunoperoxidase techniques. These observations suggest that SCLC 2051 and SCLC 5023 may be of value in identifying tumor-associated antigens expressed in small cell and other lung carcinomas. In addition, the generation of antibody-producing cells towards common tumor-associated antigens may be enhanced by immunization with multiple tumor cell lines of the same histological type.     

Biodistribution of a radiolabelled monoclonal antibody NY3D11 recognizing the neural cell adhesion molecule in tumour xenografts and patients with small-cell lung cancer.

The neural cell adhesion molecule (NCAM) is highly expressed on the surface of small-cell-lung cancer (SCLC) cells. We have produced a monoclonal antibody, NY3D11, that binds to NCAM to investigate whether this antigen could be used to develop antibody-directed therapy for SCLC. 125I-labelled IgG and F(ab'')2 fragments of NY3D11 localized selectively in human SCLC xenografts grown in nude mice. The human biodistribution of 131I-labelled NY3D11 after intravenous administration was investigated by gamma-camera imaging in six patients with SCLC. Three patients received IgG and three received F(ab'')2. No evidence of localization to primary tumours or metastases was seen and antibody accumulated rapidly in the liver and bone marrow. The probable explanation for this distribution is that NY3D11 reacted with soluble NCAM or natural killer cells that possess the CD56 (NCAM) antigen.     

BASIC STUDY AND PHASE I CLINIC TRIAL OF ANTI-IDIOTYPIC ANTIBODY MIMICKING NASOPHARYNGEAL CARCINOMA CELL ANTIGEN

Becauseofthespecialroleofanti-idiotypic(anti-id)antibodies(Abs)inimmunenetwork,itspotentialroleintumorimmunotherapyandimmunopreventionhasdrawnwideinterest.Anti-idAbsmimickingcoIorectalcarcinoma-associatedantigenandhumanhighmolecularweightmelanoma-associatedantigen(HMW-MAA)havebeenpreparedandtriedforactiveimmunotherapyontumorpatients.l-6Buttherehasn'tbeenanyrepoftaboutanti-idAbofnasopharyngealcarcinoma(NPC).NPCisatumorwithhighepidemicincidenceinChinaandSoutheastAsia,therehasn'tbeenmuchst…     

Isolation and characterisation of a human anti-idiotypic scFv used as a surrogate tumour antigen to elicit an anti-HER-2/neu humoral response in mice

HER-2/neu is a tumour antigen that is overexpressed in human breast tumours. Among the vaccine strategies developed to overcome immune tolerance to self-proteins, vaccination with anti-idiotypic (anti-Id) antibodies has been described as a promising approach for treatment of several malignant diseases. To develop an active immunotherapy for cancer patients positive for HER-2/neu, we investigated immunisation with human anti-Id single-chain fragments (scFv) mimicking the conformation of HER-2/neu protein to induce a humoral response in mice. We selected by phage display two human anti-Id scFv (Ab2beta) directed against trastuzumab F(ab')2 fragments (Ab1), a humanised anti-HER-2/neu monoclonal antibody. Using competitive ELISA and Biacore biosensor analysis, we showed that anti-Id scFv 40 and scFv 69 could inhibit HER-2/neu binding to trastuzumab. Following vaccination of BALB/c mice with the soluble or phage-displayed scFv, Ab3 polyclonal antibodies, and among them Ab1' antibodies able to bind HER-2/neu, were detected in the sera of the immunised mice. These results demonstrate that the human anti-Id scFv could act as a surrogate antigen for HER-2/neu. The present study strongly suggests that the novel 30 kDa human mini-antibody could be used as an anti-idiotype-based vaccine formulation to induce an effective humoral response in patients bearing HER-2/neu-positive tumours.     

Tumor-cell killing by MAbs against fucosyl GM1, a ganglioside antigen associated with small-cell lung carcinoma.

Monoclonal antibodies (MAbs) reactive with the ganglioside fucosyl GM1 (Fuc-GM1), an antigen associated with small-cell carcinoma of the lung (SCLC), were tested for their ability to mediate tumor-cell killing in vitro in conjunction with humoral and cellular effectors and to inhibit tumor engraftment in nude mice in vivo. MAbs F12 and F15, both IgG3k, induced human complement-mediated cytolysis of 3 Fuc-GM1-expressing tumor cell lines: one rat hepatoma cell line, H4-II-E, and 2 human SCLC cell lines, NC1 H69 and NC1 H128. F12 and F15 also induced ADCC of these cell lines in the presence of either murine or human effector cells. Addition of sub-cytolytic amounts of fresh human serum as complement source resulted in enhanced ADCC induced by MAb F12 (IgG3). Also a Fuc-GM1-reactive MAb of IgM isotype, F9, was able to induce such complement-aided ADCC (CADCC). F12 and F15 both proved to effectively inhibit engraftment of H4-II-E tumors in nude mice. A single dose of a modest amount (40 micrograms) of MAb conferred 65 to 100% protection against development of tumors. Our results demonstrate that Fuc-GM1 can act as a target antigen on tumor cells for specific immunotherapy in vitro and in a mouse model in vivo. Complement and murine and human mononuclear effector cells were effective mediators of tumor cytolysis in vitro in the presence of murine Fuc-GM1-reactive MAbs. Our results also suggest that humoral and cellular effectors may co-operate in specific tumoricidal reactions and that these may be induced by antibodies of both IgG and IgM isotypes.