Epitope analysis of human cytomegalovirus glycoprotein complexes using murine monoclonal antibodies

A panel of 10 monoclonal antibodies reactive with human cytomegalovirus (HCMV) glycoproteins was generated. These antibodies immunoprecipitated disulfide-linked complexes which contained glycoproteins with molecular weights of 130,000, 93,000, and 52,000. These complexes were designated gC-I. Epitope analysis of gC-I was done with a simultaneous two antibody binding assay. A network of epitopes was revealed which clustered in three major domains designated I, II, and III. Antibodies within individual domains I and II showed strong mutual inhibition of each other's binding. However, there were multiple antibody interactions between domains I and II. For example, the binding of most antibodies in domain I was augmented to some extent by antibodies from domain II. However, the binding of only one antibody from domain II was augmented by all antibodies from domain I. The augmentation in binding between two antibodies was dependent on the native structure of gC-I and was sensitive to conformational changes due to nonionic detergent extraction of gC-I and/or disruption of disulfide bonds. A synergistic effect was also observed between antibodies in domains I and II in a virus neutralization assay. A neutralizing antibody had a much greater neutralizing activity in the presence of a nonneutralizing antibody, which also enhanced the binding of the neutralizing antibody in the simultaneous two antibody binding assay. Also, two antibodies which were nonneutralizing individually were neutralizing when used in combination. Such antibodies also augmented each other's binding in the simultaneous two antibody binding assay. Finally, domain III consisted of a nonneutralizing antibody that inhibited the binding of all antibodies in domains I and II. This antibody also inhibited the neutralizing activity of a neutralizing antibody in a virus neutralizing assay.     

Clinical research of specific IgE and IgG4 antibody in allergic children. Correlation specific IgE antibody to specific IgG4 antibody to food allergen

We analysed the correlation specific IgE antibodies to specific IgG4 antibodies to food allergens in 150 asthmatic children by Multiple Factor Analysis-Type II and examined the role of both antibodies. The following results were obtained. 1) Of soybean, there was the stronger influence power between specific IgE and IgG4 antibody than the other 2 food allergens. 2) IgE antibody to soybean had the strong influence power to IgG4 antibodies to egg white and cow's milk and IgG4 antibody to soybean had same influence power to IgE antibodies to egg white and cow's milk. So, the specific IgE and IgG4 antibodies to soybean may be play the role of "the bride" between specific IgE antibody group and specific IgG4 antibody group of food allergens.     

A rapid and simple ELISA for the determination of duplicate monoclonal antibodies during epitope analysis of antigens and its application to the study of C1(-)-INH

A rapid and simple ELISA has been developed for identifying the specificities of two monoclonal antibodies recognizing either similar or distinct epitope(s) of an antigen. The method utilizes microtiter plates coated with one of the monoclonal antibodies either by direct adsorption of the purified antibody to the plastic or by immobilization of the antibody from ascites or hybridoma supernatants via immobilized polyclonal anti-mouse immunoglobulin antibodies. After preincubation of the antigen with the second monoclonal antibody, the mixture is added to the surface-immobilized first antibody. The amount of antigen bound to the first antibody is subsequently measured by rabbit polyclonal antibodies to the antigen and peroxidase-conjugated anti-rabbit immunoglobulin antibodies. Binding of antigen to the first antibody is only observed when the second monoclonal antibody binds to a distinct epitope. The major advantages of this procedure are its simplicity, rapidity and independence of radioisotopes. Using this method a library of monoclonal antibodies against human C1(-)-INH has been tested and several duplicate monoclonal antibodies have been identified. Furthermore, the above analytical procedure was capable of detecting conformational changes of the C1(-)-INH molecule induced either by binding of a monoclonal antibody to C1(-)-INH or by enzymatic cleavage of C1(-)-INH.     

Strategies to Extend Plasma Half-Lives of Recombinant Antibodies

Recombinant antibodies, including whole antibodies, antibody fragments, antibody fusion proteins or conjugates, and more recently also small antibody mimetics, have found increasing applications as therapeutics, e.g. for the treatment of cancer or inflammatory diseases. While whole antibodies have an exceptionally long half-life, small antibody derivatives often suffer from rapid elimination from the circulation. In order to improve administration and therapeutic efficacy, modifications to extend the plasma half-life have been developed and implemented in these antibody formats. This review provides a comprehensive summary of the various strategies currently available to extend plasma half-lives of recombinant antibodies.     

Discrimination of epitopes identified by monoclonal antibodies by competitive binding to nitrocellulose bound antigens

A new method is described for determining the distribution of epitopes identified by monoclonal antibodies. The method utilizes nitrocellulose membranes as a solid support for antigens which are rapidly adsorbed to nitrocellulose by vacuum-blotting and then used in competitive antibody binding assays. The distribution of epitopes is established by the reciprocal cross-blocking of radiolabeled antibody by increasing concentrations of unlabeled antibody. When unlabeled antibody does not block the binding of labeled antibody to antigen, the 2 antibodies recognize distinct epitopes. When unlabeled antibody blocks the binding of labeled antibody to antigen, the 2 antibodies recognize the same epitope. The method is rapid, sensitive and should be applicable to screening monoclonal antibodies to any epitope.     

人源抗乙肝表面抗原基因工程抗体的研究

目的 研制人源抗乙肝表面抗原(HBsAg)基因工程抗体.方法 采集多个HBsAg加强免疫后表面抗体阳性(HBsAb+)志愿者的外周血,分离淋巴细胞,构建人源抗HBsAg Fab噬菌体抗体基因文库.用纯化的HBsAg对抗体库进行富集筛选,经过序列测定确定抗体轻重链型别,分别克隆入真核细胞表达载体pAc-FcR和HL51-14,转染昆虫Sf9细胞和293T细胞,利用杆状病毒/昆虫细胞系统和哺乳动物细胞系统实现全抗体的分泌型表达.结果 成功筛选出20株抗HBsAg的人源Fab抗体并制备出其中6株的IgG全抗体,竞争性ELISA结果显示6株全抗体针对的是HBsAg 3个不同表位.结论 成功筛选并获得了6株针对3个不同表位的抗HBsAg的IgG全抗体,为治疗性抗体和新疫苗的研制奠定了基础.     

Association of vimentin antibody and other non-HLA antibodies with treated antibody mediated rejection in heart transplant recipients

Non-human leukocyte antigen (HLA) antibodies have been implicated in heart transplantation rejection. However, targets of non-HLA antibodies remain elusive. Here, we utilized a panel of multiplex beads-based assay to determine the specificity of non-HLA antibodies following heart transplantation. We utilized a selected cohort of recipients who did not have HLA donor specific antibodies, but were diagnosed with antibody mediated rejection and treated for antibody mediated rejection. We found the presence of vimentin antibody was associated with treated antibody mediated rejection. Our results suggest that, in heart transplant recipients who are suspected of AMR but in the absence of HLA donor specific antibodies, non-HLA antibodies should be examined.     

噬菌体展示抗体库技术的研究进展及临床应用

治疗性抗体的发展,主要经历了异源性抗体、人源化抗体和人源性抗体几个阶段。目前,人源性抗体是治疗性抗体发展的主要方向,而噬菌体抗体库构建技术为人源性抗体的制备提供了良好的技术平台。噬菌体展示抗体库构建技术,是一种将抗体组合文库与噬菌体表面展示技术相结合所形成的新技术,是20世纪90年代初期抗体工程领域的一项重大进展,目前广泛应用于生物医学的多个方面。将就此技术的原理、分类、筛选方法及主要应用领域等方面进行综述。     

Monoclonal antibodies to human intermediate filament proteins. III. Analysis of tumors

A panel of monoclonal antibodies to human intermediate filament proteins was tested on an unselected series of 246 neoplasms. The antibody panel includes two different anti-cytokeratin antibodies, an anti-vimentin antibody, and an anti-neurofilament antibody (Gown and Vogel, Am J Pathol 114:309, 1984). The studies were done on Carnoy's or methacarn-fixed, paraffin-embedded tissue. When used as a panel, they can unequivocally distinguish carcinomas, melanomas, and lymphomas. All carcinomas react with at least one of the anti-cytokeratin antibodies, and carcinomas can be subtyped based upon the pattern of reactivity with the two anti-cytokeratin antibodies. Melanomas react only with the anti-vimentin antibody, and lymphomas react with none of the antibodies. Neural and neuroendocrine tumors can be identified with the anti-neurofilament antibody. A minority of neoplasms, including lymphomas, seminomas, and some sarcomas, do not react with any of the antibodies. These antibodies are reliable diagnostic reagents that are useful in distinguishing different categories of human tumors.     

Kinetics of Epstein-Barr Virus (EBV) Neutralizing and Virus-Specific Antibodies after Primary Infection with EBV

Prospective studies of antibodies to multiple Epstein-Barr virus (EBV) proteins and EBV neutralizing antibodies in the same individuals before, during, and after primary EBV infection have not been reported. We studied antibody responses to EBV in college students who acquired primary EBV infection during prospective surveillance and correlated the kinetics of antibody response with the severity of disease. Neutralizing antibodies and enzyme-linked immunosorbent assay (ELISA) antibodies to gp350, the major target of neutralizing antibody, reached peak levels at medians of 179 and 333 days after the onset of symptoms of infectious mononucleosis, respectively. No clear correlation was found between the severity of the symptoms of infectious mononucleosis and the peak levels of antibody to individual viral proteins or to neutralizing antibody. In summary, we found that titers of neutralizing antibody and antibodies to multiple EBV proteins increase over many months after primary infection with EBV.     

Rapid screening and selection of monoclonal antibodies by bivariate flow cytometric analyses

We describe a bivariate flow cytometric assay to rapidly identify hybridomas producing new monoclonal antibodies recognizing subpopulations that are unreactive with existing immunological reagents. In this screen, whole cells in microtiter wells are labeled first with a red-linked test antibody, and then with a green-linked cocktail of existing monoclonal antibody reagents. The multiply-stained fluorescent cells are analyzed flow cytometrically and bivariate distributions of red vs. green-linked antibody fluorescence are generated. Test antibodies that recognize different subpopulations than those labeled by antibodies in the cocktail are readily identified. The use of an antibody cocktail conjugated with a single fluorophore allows comparison of the reactivity of the test antibody with multiple existing antibodies in a single analysis. This screen allows rapid (approximately 100 test antibodies can be evaluated in 40 min) identification of potentially interesting new antibodies for discrimination of subpopulations in heterogeneous tissues. We describe application of this assay to identify antibodies useful to mark hemopoietic subpopulations.     

复发性流产患者HLA及血小板特异性糖蛋白抗体GPⅡb/Ⅲa表达的初步研究

目的:探讨原因不明复发性流产(RSA)患者HLA抗体和血小板特异性糖蛋白(GPⅡb/Ⅲa)抗体的表达情况。方法:对299名复发性流产的患者血浆中HLA抗体和GPⅡb/Ⅲa抗体进行检测,血小板抗体检测试剂盒(固相凝集法)筛查IgG抗体,Antigen Tray-LATM板检测HLA抗体,GTI公司PAK-PLUS检测试剂盒检测血小板特异性抗体,利用流式细胞仪技术进行GPⅡb/Ⅲa抗体的确证。结果:检测的299例RSA患者中,IgG抗体阳性26例,阳性率8.69%。26例IgG抗体阳性患者中,25例HLA抗体呈阳性。HLA-Ⅰ类抗体阳性占5.02%,HLA-Ⅱ类抗体阳性占1.33%,HLA-Ⅰ+Ⅱ类抗体阳性占2.01%;在26例RSA患者中,GPⅡb/Ⅲa抗体阳性4例(占15.38%),其中GPⅡb/Ⅲa阳性和HLA抗体均阳性3例(占11.54%),GPⅡb/Ⅲa抗体单独阳性1例(占3.85%)。结论:初步探讨了RSA患者HLA抗体和GPⅡb/Ⅲa抗体的分布情况,本研究为复发性流产患者血小板抗体的检测提供了初步的实验基础。     

Quantitation of antibody isotypes in solid-phase assays. Comparison of myeloma protein and monoisotypic antibody standards

Two methods have been proposed for the standardization of isotype specific antibody assays. In one, myeloma proteins directly attached to plastic surfaces are used as standards, whereas the other method employs antigen coated surfaces followed by monoisotypic antibodies as standards. These standardization methodologies have been investigated by submitting 4 monoisotypic human antibodies to a solid-phase assay standardized by the myeloma method. Specific antibody concentrations of each were determined so that each could serve as a monoisotypic standard. Three purified monoclonal mouse antibodies were also tested which allowed use of the same preparation as a monoisotypic antibody standard or as a 'myeloma protein' standard. Ten times more myeloma protein than specific antibody is needed for the same level of binding of the anti-isotype antibody. Therefore, assays standardized with myeloma proteins give erroneously high concentrations for sample antibodies. The same concentration of antibodies of different specificities (used with different antigen coats) gave very comparable levels of binding of the labeled antibody. This supports the claim that for quantitation of antibodies an antibody standard can be used that is of different specificity to the sample antibody to be measured.     

Transfer of anti-HLA-DR antibodies from the mother to the child Are DR antigens expressed on the placenta?

Materno-foetal transfer of anti-HLA-DR antibodies was studied in 7 women. In 6 cases, the antibody was induced by the current pregnancy and in one case, it was a residual antibody from a previous pregnancy. When the maternal antibody was induced by the current pregnancy, no anti-DR antibody was detected in the child. When the antibody was residual, it was weakly present in the child. A comparison was made between the materno-foetal transfer of anti-HLA-A,B,C antibodies and that of anti-DR antibodies. Anti-HLA-DR antibody placental absorption suggested that the corresponding antigens were expressed on certain placenta cells.     

Role of Humoral Immunity in Host Defense Against HIV

Individuals infected with HIV-1 and nearly everyone vaccinated with HIV-1 vaccines will, in time, generate antibodies against viral proteins. These antibodies do not resolve natural infection, and vaccine candidates that successfully stimulate the production of high titers of neutralizing antibodies have failed to protect against infection. In spite of this, antibodies continue to be a focus of vaccine research. One reason for the continued interest in antibodies is the failure of a vaccine engineered to generate cell-mediated immunity against HIV. Successful protective immunity against most intracellular pathogens involves several arms of the immune response. A successful vaccine should also stimulate both protective cell-mediated immunity and specific antibody. Efforts should be directed toward making a vaccine that will stimulate the production of 1) more antibody, 2) more broadly cross-reactive neutralizing antibody (broadly neutralizing antibodies), and 3) antibody with a particular functional activity (antibody-dependent cell-mediated cytotoxicity; catalytic antibodies).     

Induction of Salivary Antibody Responses in Rats after Immunization in Peyer''s Patches

We examined salivary, milk, and serum antibody levels after immunization in the Peyer's patches (Pp) of rats with horse spleen ferritin. Priming of the Pp one day after parturition led to the appearance of IgG, but not IgA or IgM, anti-ferritin antibodies in saliva 9 days later. IgG and IgM antibodies were detected both in milk and in serum, whereas IgA antibodies could only be demonstrated in milk. During a second lactation period the salivary antibodies had vanished but IgG antibodies could still be detected in milk and serum. During a third lactation period, when the rats were immunized in the Pp a second time, not only IgG but also IgA anti-ferritin antibodies appeared in the saliva. Salivary IgG antibody levels and milk IgG, IgM, and IgA antibody levels were higher than those observed after primary immunization in the Pp. The IgG antibody activity in the saliva was positively correlated to the serum IgG antibody activity. It is concluded that salivary IgA antibody responses can be induced by immunization in the Pp. The results of this study suggests that IgA antibodies detected in saliva are produced locally by cells that have migrated from the intestinal lymphoid tissue to the salivary glands.     

Identification of scFv antibody fragments that specifically recognise the heroin metabolite 6-monoacetylmorphine but not morphine

Use of phage display of recombinant antibodies and large repertoire naïve antibody libraries for identifying antibodies of high specificity has been extensively reported. Nevertheless, there have been few reported antibodies to haptens that have originated from naïve antibody libraries with potential use in diagnostics. We have used chain shuffling of lead single-chain fragment variable (scFv) antibodies, isolated from a naïve antibody library, to screen for antibodies that specifically recognise the major metabolite of heroin, 6-monoacetylmorphine (6MAM). The antibodies were identified by screening high-density colonies of Escherichia coli expressing soluble scFv antibody fragments without prior expression on bacteriophage (phage display). The antibodies recognise 6MAM with affinities of 1–3×10⁻⁷ M with no crossreactivity to morphine. These antibodies can potentially be used for developing a rapid immunoassay in drug-testing programs. To our knowledge, this is the first report of an antibody that distinguishes 6MAM from its de-acetylated form, morphine.     

HCV感染后NS5区抗体的动态观察与检测意义

本文报道用ＨＣＶＮＳ５区两段抗原性较好的合成肽研制的ＥＬＩＳＡ试剂盒及ＵＢＩＨＣＶＮＳ５区抗体检测ＥＬＩＳＡ试剂盒观察１４例ＨＣＶ感染者ＮＳ５区抗体的动态变化，证实ＮＳ５区抗体如同ＮＳ４区抗体一样比Ｃ及ＮＳ３区抗体出现晚。ＮＳ５区抗体总体检出率近似于ＮＳ４区抗体；１．５５％的血清为单独ＮＳ５区抗体阳性；存在ＮＳ５区抗体与其他区抗体滴度有互补作用的标本等提示ＮＳ５区抗体仍有一定的诊断价值。采用ＵＢＩＮＳ５区抗体检测试剂盒发现，９５．６５％（２２／２３）ＵＢＩ试剂盒诊断为ＮＳ５区抗体阳性的标本中含ＨＣＶＲＮＡ，６／１４ＨＣｖ感染者用ＵＢＩ试剂盒检出的抗体出现在ＡＬＴ再次异常升高或剧烈升高（高于参考值的３倍以上）前后，４／１４的感染者抗体出现于ＡＬＴ首次升高前后（其余４／１４的感染者未检出抗ＮＳ５抗体），因此ＵＢＩ抗ＨＣＶＮＳ５抗体诊断试剂盒检测的抗体似与疾病的活动有关。     

Identification of HBsAg-specific antibodies from a mammalian cell displayed full-length human antibody library of healthy immunized donor

Hepatitis B immunoglobulin (HBIG) is important in the management of hepatitis B virus (HBV) infection. Aiming to develop recombinant monoclonal antibodies as an alternative to HBIG, we report the successful identification of HBV surface antigen (HBsAg)-specific antibodies from a full-length human antibody library displayed on mammalian cell surface. Using total RNA of peripheral blood mononuclear cells of a natively immunized donor as template, the antibody repertoire was amplified. Combining four-way ligation and the Flp recombinase-mediated integration (Flp-In) system, we constructed a mammalian cell-based, fully human, full-length antibody display library in which each cell displayed only one kind of antibody molecule. By screening the cell library using fluorescence-activated cell sorting (FACS), eight cell clones that displayed HBsAg-specific antibodies on cell surfaces were identified. DNA sequence analysis of the antibody genes revealed three unique antibodies. FACS data indicated that fluorescent strength of expression (FSE), fluorescent strength of binding (FSB) and relative binding ability (RBA) were all different among them. These results demonstrated that by using our antibody mammalian display and screening platform, we can successfully identify antigen-specific antibodies from an immunized full-length antibody library. Therefore, this platform is very useful for the development of therapeutic antibodies.     

Heterophile antibodies indicate progression of autoimmunity in human type 1 diabetes mellitus before clinical onset

We previously reported serum cytokines in a group of long term non-progressors to Type 1 diabetes; this reactivity detected in ELISA is now identified as heterophile antibody in some sera. Here, we characterize heterophile antibody activity. A 14 kDa-polypeptide from heterophile antibody containing serum bound to an anti-IL-4 column, but IL-4 was not detected by Western blot or by MS/MS sequencing. However, in 2/13 heterophile antibody positive sera, T-cell growth was potentiated and was blocked by an anti-human immunoglobulin. To examine the relationship between low affinity heterophile antibody presence and disease progression, 1100 archived serum samples were analyzed with two pairs of antibodies from 443 diabetes-free first degree relatives of Type 1 diabetes mellitus patients for heterophile antibody; 95 individuals developed diabetes on follow-up. Twenty-two individuals, whose serum was heterophile antibody positive with the second pair of antibodies (but negative with the first pair of antibodies), had a significantly higher incidence of developing diabetes after five years. Thirty-seven individuals with heterophile antibody reactivity with the first pair of antibodies, regardless of reactivity with the second pair of antibodies, had a significantly lower incidence of developing diabetes. While we cannot exclude the presence of genuine cytokine in all sera, these data indicate the presence of distinct groups of heterophile antibodies in patients at high risk to develop diabetes. Thus, anti-Ig heterophilic antibodies with different immunochemical reactivities are linked to the progression of or protection from Type 1 diabetes autoimmunity.