消减免疫法制备克伦特罗单克隆抗体

目的：制备克伦特罗（CL）单克隆抗体。方法：重氮化法制备克伦特罗完全抗原,消减免疫法免疫BALB／c小鼠,常规杂交瘤技术制备抗克伦特罗单克隆抗体。结果：消减免疫法使小鼠获得了对BSA的耐受,单抗筛选过程中获得了高达8．2％的阳性率。最后得到了针对CL的特异性抗体。结论：用消减免疫法制备针对小分子污染物的单克隆抗体,可减少在制备单克隆抗体时筛选的工作量,可增加获得预期抗体的机会。     

DNA免疫技术在单克隆抗体开发中的研究进展

DNA免疫是将编码特异性抗原的重组表达载体转入动物体内,特异性基因序列在动物体内得以表达并诱导产生其特异性抗体的一系列免疫应答过程。目前,DNA免疫已成为多种保护性以及诊断性单克隆抗体研究和开发的主要技术手段,尤其对于在体外难以表达和纯化的抗原,DNA免疫比传统的蛋白免疫占绝对优势。DNA免疫在宿主细胞内表达抗原及递呈方式类似于病毒感染,既能产生体液免疫,又能产生细胞免疫,由此克服了传统蛋白质免疫方法的缺陷,为制备高质量单克隆抗体提供了良好的技术平台。然而这项技术在实践应用中遇到了不少挑战,尤其是以传统的肌肉注射法免疫单一的质粒DNA,使递送效率和抗体表达水平都很低,导致DNA免疫的低免疫原性。综述了DNA免疫技术在单克隆抗体开发中的应用,对DNA免疫相关概念、诱导机制、载体的构建、递送方式、不同免疫佐剂的影响、优点和发展前景等方面进行论述,旨在为DNA免疫技术在制备高质量单克隆抗体中的应用以及提高其免疫效率提供有效的理论知识。     

1组曲霉单克隆抗体的制备与鉴定

目的制备并鉴定一组抗曲霉不同抗原的单克隆抗体。方法采用烟曲霉细胞壁抗原成分、分泌抗原和灭活分生孢子,分别免疫BALB／c小鼠,制备单克隆抗体,免疫荧光法鉴定单克隆抗体与曲霉属和念珠菌属抗原的交叉反应。结果获得29株稳定分泌抗曲霉单抗的杂交瘤细胞株,其中用烟曲霉细胞壁抗原成分免疫获得11株,用分泌抗原免疫获得13株,用孢子免疫获得5株;Ig亚类鉴定,11个克隆株为IgG1亚类,3个克隆株为IgG3,15个克隆株为IgM。免疫荧光法鉴定29株单抗特异性识别烟曲霉细胞壁抗原,与其他曲霉抗原有交叉反应。结论29株单克隆抗体,对于建立侵袭性曲霉感染早期诊断方法、筛选曲霉保护性抗体以及研究抗体保护机制奠定了实验基础。     

群特异性蓝舌病病毒单克隆抗体的制备和鉴定

目的：制备群特异性抗蓝舌病病毒（BTV）单克隆抗体,并对其特性进行鉴定,为建立检测BTV抗原及抗体的ELISA方法奠定基础。方法：用纯化的BTV颗粒为免疫抗原免疫BALB/c鼠,以大肠杆菌表达的VP7蛋白作为筛选抗原,用间接ELISA法筛选杂交瘤细胞株;选取抗体效价最高的一株制备BTV单克隆抗体,以该抗体为捕获抗体与8种不同血清型BTV进行ELISA反应,结果与细胞病变反应进行比对;以该抗体为竞争抗体,与12种不同血清型绵羊BTV抗血清进行竞争ELISA反应,并将结果与参比c-ELISA试剂盒结果进行比对。结果：筛选出5株稳定分泌BTV单克隆抗体的杂交瘤细胞株,并选其中一株（3E2）制备了高纯度的单克隆抗体;该单抗用于检测不同血清型BTV,与细胞病变反应结果完全相符;用于检测不同血清型绵羊BTV抗血清,其结果与参比c-ELISA试剂盒符合率为100%,与鹿流行性出血热病毒抗原和抗体均无交叉反应。结论：制备的BTV单克隆抗体具有良好的群特异性,可用于检测不同血清型BTV抗原及BTV抗体。     

博尔纳病病毒抗原免疫的杂交瘤细胞系的评价

目的评价博尔纳病病毒(BDV)抗原免疫的杂交瘤细胞系的产生抗体能力与抗体特异性。方法随机抽取2株由BDV抗原免疫的杂交瘤细胞系H1和H2,通过体内和体外方法制备单克隆抗体,通过间接免疫荧光、免疫印迹和间接酶联免疫吸附3种试验方法对制备的抗体进行特异性鉴定及效价测定。结果杂交瘤细胞系H1和H2可以产生一定效价的单克隆抗体,并对BDV的P24和P40抗原具有特异性。结论由杂交瘤细胞系H1和H2产生的单克隆抗体可以用于检测BDV特异性抗原。     

抗人甲状腺球蛋白单克隆抗体的制备

目的:制备分泌特异性抗人甲状腺球蛋白(thyroglobulin,Tg)单克隆抗体的杂交瘤细胞株,为建立高灵敏度的Tg检测方法做准备。方法:以天然人源甲状腺球蛋白为抗原经皮下免疫BALB/c小鼠,通过细胞融合制备分泌抗人甲状腺球蛋白单克隆抗体,并对其进行特异性鉴定,建立检测Tg的双抗体ELISA(enzyme-linked immunosorbent assay)夹心法。结果:获得7株可稳定分泌抗人甲状腺球蛋白单克隆抗体的杂交瘤细胞株,经ELISA鉴定,筛选抗体可与Tg抗原有良好的特异性反应。建立的双抗体夹心ELISA方法敏感性可达1 ng/mL。结论:成功制备了抗人Tg单克隆抗体并建立了检测人Tg双抗体夹心ELISA方法,为进一步研发Tg快速诊断试剂盒提供了原料。     

粘膜耐受在预防和治疗自身免疫病中的应用

粘膜应用自身抗原诱导外周免疫耐受状态,依赖应用抗原剂量,诱导产生两种粘膜耐受机制：高剂量偏向产生Ｔ细胞克隆无能／排除,低剂量偏向产生分泌抑制性细胞因子（ＴＧＦ－β,ＩＬ－４,ＩＬ－１０）的Ｔ细胞克隆扩增。大量研究表明鼻内或口服应用抗原诱导粘膜耐受可有效预防的几种实验性自身免疫病（ＥＡＥ,ＥＡＭＧ,ＥＡＵ,ＩＤＤＭ和ＣＩＡ）,在同等剂量鼻内应用比口服诱导粘膜耐受更有效。基于动物实验结果,对人类自身免     

基于B细胞表位制备抗肝细胞生成素的抗体

目的：基于B细胞表位制备抗肝细胞生成素（HPO）的抗体。方法：根据HPO的空间结构选择了2个候选B细胞表位,展示在T7噬菌体的表面,将提取的重组噬菌体免疫动物,采用ELISA法检测抗血清的效价,通过杂交瘤技术制备针对HPOC端表位的单克隆抗体。结果：2个候选B细胞表位KDGSCD和DGWKDGSC均能诱导抗相应表位多肽的多克隆抗体的产生,免疫6周后血清中抗体效价均达到1∶103,产生的抗体还能够特异识别HPO全蛋白;针对HPOC端表位KDGSCD的单克隆抗体也能识别HPO全蛋白,且具有良好的特异性。结论：基于T7噬菌体展示的B细胞表位可作为免疫原用于制备识别该B细胞表位来源的全蛋白质的抗体。     

抗EHFV的独特型抗体在大鼠体内诱导免疫应答的研究

本文介绍用流行性出血热（EHF）病毒J10株制备单克隆抗体（McAb),以及用7个McAb免疫家兔,使其产生抗EHF病毒McAb的抗体即独特型抗体（Ab2）。Ab2能在体外同出血热病人恢复期血清和EHF病毒免疫的兔血清发生特异性结合。再经EHF－McAb亲和层析法分离提纯Ab2,免疫BALb/c小鼠,将所获得的免疫血清（Ab3）用荧光和ELISA分别加以测定,结果表明,抗－抗独特型抗体可在体外识别EHF病毒,而不能同病病人恢复期血清发生结合,从而支持免疫网络学说,可能为我们提供一种新型的抗原来源途径。     

抗EHFV的独特型抗体在小鼠体内诱导免疫应答的研究

本文介绍用流行性出血热（EHF）病毒J10株制备单克隆抗体（McAb）,以及用7个McAb免疫家兔,使其产生抗EHF病毒McAb的抗体即抗独特型 抗体（Ab2).Ab2能在体外同出血热病人恢复期血清和EHF病毒免疫的兔血清发生特异性结合。再经EHF－McAb亲和层析法分离提纯Ab2,免疫BALb/c小鼠,将所获得的免疫血清（Ab3）用荧光和ELISA分别加以测定。结果表明,抗－抗独特型抗体可在体外识别EHF病毒,而不能同病病人恢复期血清发生结合,从而支持免疫网络学说,可能为我们提供一种新型的抗原来源途径。     

Targeting the proteome/epitome,implementation of subtractive immunization

Monoclonal antibody technology has generated invaluable tools for both the analytical and clinical sciences. However, standard immunization approaches frequently fail to provide monoclonal antibodies with the desired specificity. Subtractive immunization provides a powerful alternative to standard immunization and allows for the production of truly unique antibodies. With the intent of targeting specific epitopes within the proteome, subtractive immunization has been broadly and successfully implemented for the production of monoclonal antibodies otherwise unobtainable by standard immunization. Subtractive immunization utilizes a distinct immune tolerization approach that can substantially enhance the generation of monoclonal antibodies to desired antigens. The approach is based on tolerizing the host animal to immunodominant or otherwise undesired antigen(s) (tolerogen) that may be structurally or functionally related to the antigen of interest. Tolerization of the host animal can be achieved through one of three methods: High Zone, Neonatal, or Drug-induced tolerization. The tolerized animal is then inoculated with the desired antigen (immunogen) and antibodies generated by the subsequent immune response are screened for the desired antigenic reactivity. Over the past 15 years a large number of investigators have used the subtractive approach with cleverly chosen tolerogen-immunogen combinations and successfully generated uniquely reactive antibodies which are often neutralizing or function-blocking. This review will focus on the implementation of subtractive immunization for the production of antibodies otherwise unobtainable by standard immunization.     

Enhanced immunization techniques to obtain highly specific monoclonal antibodies

Despite fast advances in genomics and proteomics, monoclonal antibodies (mAbs) are still a valuable tool for areas such as the evolution of basic research in stem cells and cancer, for immunophenotyping cell populations, diagnosing and prognosis of diseases, and for immunotherapy. To summarize different subtractive immunization approaches successfully used for the production of highly specific antibodies, we identified scientific articles in NCBI PubMed using the following search terms: subtractive immunization, monoclonal antibody, tolerization, neonatal, high-zone tolerance, masking immunization. Patent records were also consulted. From the list of results, we included all available reports, from 1985 to present, that used any enhanced immunization technique to produce either polyclonal or monoclonal antibodies. Our examination yielded direct evidence that these enhanced immunization techniques are efficient in obtaining specific antibodies to rare epitopes, with different applications, such as to identify food contaminants or tumor cells.     

Subtractive immunization techniques for the production of monoclonal antibodies to rare antigens.

Traditional techniques for the production of monoclonal antibodies usually result in generation of monoclonal antibodies to immunodominant molecules. To enhance the production of monoclonal antibodies to rare or less immunodominant antigens, subtractive immunization techniques have been employed. This study compared the ability of several subtractive immunization techniques to suppress the immune system to a given antigen. Neonatal tolerization, chemical immunosuppression with cyclophosphamide, a combination of the two and various permutations of these techniques were compared. The results from this study indicated that chemical immunosuppression with cyclophosphamide was the most effective subtractive immunization technique and that the cyclophosphamide regime employed was a critical determinant in the success of chemical immunosuppression.     

Generation of Monoclonal Antibodies against Highly Conserved Antigens

Background

Therapeutic antibody development is one of the fastest growing areas of the pharmaceutical industry. Generating high-quality monoclonal antibodies against a given therapeutic target is very crucial for the success of the drug development. However, due to immune tolerance, some proteins that are highly conserved between mice and humans are not very immunogenic in mice, making it difficult to generate antibodies using a conventional approach.

Methodology/Principal Findings

In this report, the impaired immune tolerance of NZB/W mice was exploited to generate monoclonal antibodies against highly conserved or self-antigens. Using two highly conserved human antigens (MIF and HMGB1) and one mouse self-antigen (TNF-alpha) as examples, we demonstrate here that multiple clones of high affinity, highly specific antibodies with desired biological activities can be generated, using the NZB/W mouse as the immunization host and a T cell-specific tag fused to a recombinant antigen to stimulate the immune system.

Conclusions/Significance

We developed an efficient and universal method for generating surrogate or therapeutic antibodies against “difficult antigens” to facilitate the development of therapeutic antibodies.     

Subtractive immunization yields monoclonal antibodies that specifically inhibit metastasis

Subtractive immunization allowed the isolation and characterization of monoclonal antibodies that specifically inhibit metastasis but not proliferation of highly metastatic human tumor cells. The tolerizing agent cyclophosphamide was used to suppress the immune system in mice to dominant immunodeterminants present on a non-metastatic variant (M-) of the human epidermoid carcinoma cell line (HEp3). Mice were then inoculated with a highly metastatic variant (M+) of HEp3 to enhance an immune response to antigenic determinants present on metastatic cells. Hybridomas were generated and screened by ELISA for differential reactivity to M+ HEp3 over M- HEp3 cells. This experimental approach, termed subtractive immunization (S.I.), was compared to a control immunization protocol, which eliminated the cyclophosphamide treatment. The S.I. protocol resulted in an eight-fold increase in the proportion of mAbs that react with molecules enriched on the surface of the M+ HEp3 cells. Two of the mAbs derived from the S.I. protocol, designated DM12-4 and 1A5, were purified and examined for their effect in a metastasis model system in which chick embryos are transplanted with primary HEp3 tumors. Purified mAbs DM12-4 and 1A5, inoculated i.v. into the embryos, inhibited spontaneous metastasis of HEp3 cells by 86 and 90%, respectively. The mAbs are specifically anti-metastatic in that they have no effect on the growth of HEp3 cells in vitro nor did they inhibit primary tumor growth in vivo. The mAbs recognize M+ HEp3 cell surface molecules of 55 kD and 29 kD, respectively. These data demonstrate that the S.I. protocol can be used for the development of unique mAbs that are reactive with antigenic determinants whose expression is elevated on metastatic human tumor cells and which function mechanistically in the metastatic cascade.     

An alternative strategy for high throughput generation and characterization of monoclonal antibodies against human plasma proteins using fractionated native proteins as immunogens

Construction of a monoclonal antibody (mAb) bank containing a vast variety of antibodies against human tissue proteins is important for proteomic research. A novel strategy of subtractive immunization using fractionated native proteins was developed for high throughput generation of mAb against human plasma proteins. By this novel approach, the bottleneck of antigen preparation can be overcome by combining repeated immunization of animals with subtracted fractions of plasma or tissue proteins and identification of target antigen by immunoprecipitation/mass spectrum strategies. Plasma freshly collected from healthy adults was pooled and three fractions were prepared by size exclusion chromatography. Mice were immunized with the fractionated plasma proteins, and 205 strains of hybridomas secreting mAb were obtained after two-round subtractive immunizations and cell fusions. In the first round, 110 strains of hybridomas were established, in which 77 strains secreting mAb were identified against 10 human plasma high-abundant proteins. In the second round, plasma fraction I was absorbed with mAb against IgM, IgG, ceruloplasmin and haptoglobin. The absorbed fraction I was used as immunogen for the second round immunization and cell fusion. Ninety-five strains of hybridomas secreting mAb were obtained. Although the target antigens of mAb from 82 strains of hybridomas were identified as IgM, IgA, alpha2-macroglobulin and fibrinogen, about 85% antibodies obtained from this round were identified as new antibodies when compared with mAb obtained in the first round immunization with plasma fraction I. The results suggest that subtractive immunization with fractionated plasma proteins followed by identification of antigens with immunoprecipitation/mass spectrum may be an effective approach for rapid preparation of mAb against high-and medium-abundant plasma or tissue proteins.     

Applications and optimization of immunization procedures

Classical immunization protocols have produced an antibody-based humoral response that is very effective against susceptible infectious diseases. Immunization introduces an external substance to induce the host immune system to respond specifically. Typically an antigen is used, but DNA, or a primed, pre-existing leukocyte or antigen-presenting cell, can also be used. Immunization is currently being used or investigated for the prevention and treatment of infectious diseases, cancer, addictions, allergies, pregnancy, and autoimmune diseases. It is also being used to produce biologically active materials such as polyclonal and monoclonal antibodies, antivenins, and anti-toxins for treating a wide range of conditions. Animals have been integral to the development of immunization techniques, as producers of toxoids and antitoxins, as models (e.g., to validate materials and protocols used for immunization, to understand the impact of immunization itself on the immune system, and to help investigators devise methods for determining the efficacy of vaccines) and as beneficiaries themselves of vaccines and antitoxins. The choice of immunization protocols is complex, and results may be affected by many factors such as dose and concentration of antigen, choice of adjuvants, time between inoculation and response measurement, and method of detection. The immune system responses to an antigen are also complex and continue to develop with advancing age. Anatomical, physiological, and immune system differences between species influence responses to immunization, as do the purity and presentation of the antigens and adjuvants. When directly comparing results, animals should be sourced from the same supplier. This review highlights the many uses of immunization techniques and introduces important considerations for the choice of protocols and animal models.     

Immunogenic Properties of Colloidal Gold

We studied the capacity of colloidal gold for enhancing specific and nonspecific immune response in laboratory animals (rabbits, rats, and mice) immunized with antigens of various nature. The antibody titers obtained with colloidal gold as a carrier were higher as compared to the standard immunization techniques (free antigen or its combination with Freund's adjuvant). Application of colloidal gold also enhanced nonspecific immune responses, such as lysozyme concentration in the blood, activity of the complement system proteins, as well as phagocytic and bactericidal activities. The antibodies were tested by immunodot assay using gold markers. Immunization of the animals with colloidal gold conjugates with haptens or complete antigens (without other adjuvants) was shown to induce the production of highly active antibodies. In addition, the amount of antigen used for animal immunization with colloidal gold was an order of magnitude lower, compared to immunization with complete Freund's adjuvant. This fact can be evidence for adjuvant properties of colloidal gold proper.     

The use of tolerization in the production of monoclonal antibodies against minor antigenic determinants

An initial attempt to prepare monoclonal antibodies specific for the Dictyostelium discoideum lysosomal enzyme beta-glucosidase was unsuccessful. All of the antibodies resulting from this fusion recognized an extremely immunogenic epitope that is present on all of the lysosomal enzymes of Dictyostelium. In two succeeding fusions, changes in the immunization schedule intended to increase the immune response to enzyme-specific epitopes were not entirely successful. Although nine hybridomas producing antibodies specific for beta-glucosidase resulted from these two fusions, most (70%) of the cell lines isolated secrete antibodies that recognize the shared, immunodominant epitope. Moreover, the nine beta-glucosidase-specific antibodies proved to be of limited utility since none recognize the native enzyme. Therefore, we attempted to tolerize a BALB/c mouse to the common epitope by injecting the lysosomal enzyme, N-acetylglucosaminidase, within 40 h after birth. As an adult, this animal was immunized with beta-glucosidase. Fusion of the spleen cells from this mouse with myeloma cells resulted in the isolation of nine hybridoma lines that produce antibodies specific for beta-glucosidase. No antibodies reactive with the common epitope were detected. These results suggest that tolerization may provide a means whereby an undesired class of antibody-producing cell lines can be selectively eliminated from the products of a fusion.     

Chickens with humanized immunoglobulin genes generate antibodies with high affinity and broad epitope coverage to conserved targets

Transgenic animal platforms for the discovery of human monoclonal antibodies have been developed in mice, rats, rabbits and cows. The immune response to human proteins is limited in these animals by their tolerance to mammalian-conserved epitopes. To expand the range of epitopes that are accessible, we have chosen an animal host that is less phylogenetically related to humans. Specifically, we generated transgenic chickens expressing antibodies from immunoglobulin heavy and light chain loci containing human variable regions and chicken constant regions. From these birds, paired human light and heavy chain variable regions are recovered and cloned as fully human recombinant antibodies. The human antibody-expressing chickens exhibit normal B cell development and raise immune responses to conserved human proteins that are not immunogenic in mice. Fully human monoclonal antibodies can be recovered with sub-nanomolar affinities. Binning data of antibodies to a human protein show epitope coverage similar to wild type chickens, which we previously showed is broader than that produced from rodent immunizations.