DNA免疫制备单克隆抗体的研究进展

DNA免疫是近年发展起来的一种新型抗体制备法。DNA免疫克服了传统蛋白质免疫方法的缺陷,能更为有效地激发机体的体液和细胞免疫应答。尤其是在仅知DNA编码而不能获得目的蛋白或获得的抗原蛋白为低免疫性的情况下,蛋白质免疫将很难得到特异性的抗体,但通过DNA免疫可制备高效价特异性的抗体,这为某些疾病如病毒性疾病和肿瘤等的诊断和免疫治疗开拓了新的途径。     

抗激活小鼠T细胞抗原单克隆抗体(2H3)的免疫生物学特性分析

2H3为一株抗激活小鼠T细胞表面抗原的单克隆抗体。间接ELISA法所进行的免疫球蛋白属性分析实验表明:2H3属于IgG_1型抗体。同位素H~3-TdR掺入实验表明:2H3能以剂量依赖的方式明显抑制小鼠激活T细胞及CTLL-2细胞依赖IL-2的增殖;能够明显抑制ConA诱导小鼠脾细胞转化早期(12h内)的非特异性淋巴细胞增殖反应。对不同品系小鼠间的双向混合淋巴细胞反应(MLR),2H3也表现出明显的抑制作用,且这种抑制作用具有剂量相关性和无H-2限制性。实验结果提示:2H3具有抗小鼠细胞膜表面IL-2R单克隆抗体的免疫生物学特征。     

DNA免疫法制备抗人Flt3-ligand单克隆抗体及其鉴定

Ｆｌｔ3 ｌｉｇａｎｄ(ＦＬ)是近几年新发现的一种相对分子质量 (Ｍｒ)为 30 0 0 0的糖蛋白 ,其中有Ｍｒ 为 120 0 0的糖类〔1,2〕,主要参与体内的造血调控。在体外培养体系中 ,Ｆｌｔ3 ｌｉｇａｎｄ可与ＩＬ 3,ＩＬ 6,ＳＣＦ及ＧＭ ＣＳＦ等细胞因子协同 ,刺激造血干 /祖细胞增殖 ,并能协同诱导造血干 /祖细胞分化为树突状细胞等 ,因而在造血干 /祖细胞的体外培养中获得广泛应用〔1,3〕。ＤＮＡ免疫法是一种新的制备单克隆抗体(ｍＡｂ)的免疫方法 ,它不需要制备大量抗原 ,只需将编码抗原的ｃＤＮＡ克隆到真核表达载体上 ,用重组质粒对动物…     

抗人DAF单克隆抗体的制备及鉴定

以初步纯化的人红细胞膜ＤＡＦ免疫Ｂａｌｂ／ｃ小鼠,取免疫小鼠脾细胞与ＳＰ２／０骨髓瘤细胞融合,成功地获得３株（ＤＧ３、ＤＧ９和ＤＡ１１）抗人ＤＡＦ单克隆抗体。经间接ＥＬＩＳＡ测定,３株杂交瘤细胞培养上清及腹水的抗体效价分别为１０－３～１０－４及１０－６～１０－７;３株单抗的重链为小鼠ＩｇＧ１亚类,轻链为κ型。结合还原条件下的免疫印迹实验及３株单抗对ＤＡＦ促衰变活性的抑制作用,推测ＤＧ９识别的抗原表位为ＳＣＲ１,而ＤＧ３和ＤＡ１１为ＳＣＲ２至ＳＣＲ４。     

抗肿瘤相关糖抗原sTn单克隆抗体的制备及鉴定

细胞发生转化时,经常伴随着细胞膜表面糖脂或糖蛋白糖链的改变〔１〕。在肿瘤细胞,特别是腺癌细胞,其表面粘蛋白分子的糖链经常由于合成不全而缩短,形成肿瘤相关的简单粘蛋白糖抗原,ｓＴｎ即为其中的一种〔２〕。ｓＴｎ（ＮｅｕＡｃα２→６ＧａｌＮＡｃα１→ＯＳｅｒ／Ｔｈｒ）是一种二糖结构,可表达于各种腺癌组织,而在正常组织中则很少或不表达。血清、细胞或组织中ｓＴｎ的检测,主要依赖抗ｓＴｎ的单克隆抗体（ｍＡｂ）。我们应用富含ｓＴｎ侧链的绵羊颌下腺粘蛋白（ＯＳＭ）免疫制备了抗ｓＴｎ的ｍＡｂ〔３〕,目的在于为建立检测ｓＴ…     

抗单链DNA单克隆抗体在细胞凋亡检测中的应用研究

随着对细胞凋亡研究的深入，发现凋亡与机体的健康和疾病状态息息相关。因而建立一种简便有效的检测凋亡细胞的生物学方法对于临床与基础研究非常重要。最近研究发现抗单链DNA的特异性单克隆抗体在检测细胞凋亡方面具有其它方法无可比拟的优势，如高度的特异性与敏感性，低廉的费用，故而有着广阔的应用前景。     

利用DNA免疫技术制备人CLDN18.2单克隆抗体

目的:制备CLDN18.2特异性单克隆抗体并对其特性和在免疫检测中的应用进行鉴定,为CLDN18.2的抗体药物研发奠定基础。方法:将in vivo-jetPEI-Gal和pcDNA3.1-CLDN18.2质粒在体外混合后经尾静脉免疫小鼠,筛选效价较高的小鼠进行细胞融合和单克隆筛选,制备CLDN18.2的特异性单克隆抗体,然后对获得的单克隆抗体的亲和力和特异性及其在细胞ELISA、流式细胞术、细胞免疫荧光和免疫沉淀等实验中的应用进行鉴定。结果:共获得15株有较好特异性的CLDN18.2单克隆抗体,其与CLDN18.2结合的EC50s均在纳摩尔或亚纳摩尔级,可在ELISA、免疫沉淀、流式细胞术和细胞免疫荧光实验中用于对CLDN18.2的特异检测,但均不能用于Western blot实验。结论:成功制备并获得了15株可识别蛋白天然构象、亲和力高、特异性好的小鼠抗人CLDN18.2单克隆抗体,为CLDN18.2抗体药物的研发奠定了重要基础。     

抗人滋养细胞单克隆抗体的制备及其免疫生物学特性鉴定

研制抗人滋养细胞单克隆抗体并分析其免疫生物学特性。方法采用滋养细胞免疫Ｂａｌｂ／ｃ小鼠;用细胞ＥＬＩＳＡ法鉴定ｍＡｂ的特异性;用补体依赖的溶细胞作用测定ｍＡｂ的细胞毒性。结论利用细胞免疫法所获该组ｍＡｂ所针对的抗原表位,可能是诱发免疫性流产的滋养细胞膜特异性抗原。     

DNA immunization followed by a single boost with cells: a protein-free immunization protocol for production of monoclonal antibodies against the native form of membrane proteins

Recent advancements in antibody-based therapies require the development of an efficient method for generation of monoclonal antibodies (MAbs) against the native form of membrane proteins. We examined DNA immunization followed by a single boost with cells as a protein-free immunization protocol for production of MAbs. Mice immunized with plasmid cDNAs encoding human CD30 or Ret tyrosine kinase were given a single boost with cells expressing the corresponding antigen prior to cell fusion. A total of nine cell fusion experiments revealed that the cell boost is necessary for efficient generation of hybridomas and the DNA-cell boost method gave good yields of specific MAbs (5–59 MAbs from one mouse). All IgG isotypes except IgG3 were generated, although IgG2a was the dominant isotype. All the MAbs reacted with native antigens expressed on cells in a fluorescence-activated cell sorter (FACS) analysis as well as with recombinant CD30 or Ret protein genetically fused with human Fc in an enzyme-linked immunosorbent assay (ELISA). The affinities of the anti-CD30 MAbs to CD30-Fc protein ranged from 0.9 to 12.4 nM K_ds, which were comparable to existing MAbs to these proteins, which range from 3.0 to 13.0 nM. Western blot analysis and topographical epitope mapping experiments based on the mutual competition of pairs of the anti-CD30 MAbs revealed that about 40% of the epitopes were linear epitopes and that each epitope was topographically classified into one of six groups. The large number of MAbs that react with high affinities to a variety of epitopes on the native form of antigens indicates that the method presented in this paper could be generally useful for generating MAbs to other membrane proteins.     

Production of polyclonal and monoclonal antibodies against CD54 molecules by intrasplenic immunization of plasmid DNA encoding CD54 protein

DNA immunization, in theory, is of great interest as a source of specific antibodies against different antigens. In an attempt to produce polyclonal and monoclonal antibodies against cell surface molecules by using the DNA immunization strategy, intramuscular and intrasplenic routes of DNA injection were compared. Two to five, but not a single, intramuscular DNA immunizations induced anti-CD54 and anti-CD147 antibody production. In contrast, a single intrasplenic immunization of CD54-encoding DNA could induce anti-CD54 antibody production. To produce monoclonal antibody (mAb), spleen cells obtained from an intrasplenic CD54-encoding DNA immunized mouse were fused with myeloma cells using the standard hybridoma technique. A hybridoma secreting specific mAb to CD54 was established. The generated mAb reacted to CD54 protein expressed on transfected COS cells and various cell types, the same as using standard CD54 mAb MEM-111. Our results demonstrated that direct immunization of antigen-encoding DNA into spleen is an effective route for production of both polyclonal and monoclonal antibodies to cell surface molecules. This finding is very useful for the production of antibodies to cell surface molecules where the protein antigen is not available or difficult to prepare, but cDNA encoding the corresponding protein is available.     

Production of anti-dengue NS1 monoclonal antibodies by DNA immunization

Monoclonal antibodies against dengue NS1 protein were generated following immunization of mice with plasmid DNA encoding the transmembrane form of NS1 from dengue serotype 2 virus. A mammalian expression vector, pDisplay, was engineered to direct cell surface expression of dengue NS1 and tested for transient expression in COS cells. Two mice were immunized intramuscularly with six doses of 100 microg of plasmid at 2-week intervals; one mouse received a booster of live virus prior to the last plasmid injection. Both mice showed antibody responses against dengue antigens in dot enzyme immunoassay. Following fusion, hybridomas were screened with dot enzyme immunoassay against all four dengue serotypes. Specificity to the NS1 protein was confirmed by western blot analysis. Among five anti-dengue NS1 monoclonal antibodies generated, two clones were serotype 2 specific, two clones reacted with all four serotypes and the last also reacted with Japanese encephalitis virus. Reactivity against native or denatured forms of NS1 revealed three clones with reactivity to linear epitopes and two clones recognizing conformational epitopes. Such diverse specificity of anti-dengue NS1 monoclonal antibodies indicates that DNA immunization, especially with the combination of virus boosting, is an efficient way of producing monoclonal antibodies against viral protein. This has opened up a possibility of producing monoclonal antibodies to rare viral proteins that are difficult to isolate or purify.     

Production of a monoclonal antibody against SARS-CoV spike protein with single intrasplenic immunization of plasmid DNA

Severe acute respiratory syndrome (SARS) is a highly infectious disease caused by a novel coronavirus (SARS-CoV). Specific monoclonal antibodies (mAbs) against the SARS-CoV are vital for early diagnosis and pathological studies of SARS. Direct intrasplenic inoculation of plasmid DNA encoding antigen is an effective and fast approach to generate specific mAb when the protein antigen is difficult to prepare or dangerous in use. In this study, we selected one fragment of SARS-CoV spike protein (S1-₃) as antigenic determinant by immunoinformatics. Single intrasplenic immunization of plasmid DNA encoding S1-₃ induced anti-spike protein antibodies. We established one hybridoma cell line secreting specific mAb and evaluated this mAb with murine leukemia virus pseudotyped with SARS-CoV spike protein (MLV/SARS-CoV). The mAb could recognize the spike protein on the MLV/SARS-CoV-infected Vero E6 cells albeit with no neutralizing effect on the infectivity of the pseudotype virus. Our results show that a single-shot intrasplenic DNA immunization is efficient for the production of specific mAb against SARS spike protein, and a linear epitope of the spike protein is recognized in this study.     

Production and characterization of monoclonal antibodies against DNA single ring diamines adducts

The synthetic conjugate of the genotoxic compound 2,4 diaminotoluene (2,4 DAT) with gelatin (2,4 DAT-GEL) was employed to elicit specific antibodies directed against a restricted class of aromatic diamines. Using this immunogen, mouse monoclonal antibodies (MAbs) have been produced. These MAbs have been characterized and used in ELISA to detect 2,4 DAT covalently linked to biopolymers. The MAbs could bind to different synthetic 2,4 DAT-biopolymer adducts as well as to DNA from rats treated in vivo with the aromatic diamine, but they did not react with gelatin or biopolymers alone. The use of these MAbs has been investigated in order to develop a highly sensitive test to detect adducts of this genotoxic compound with nuclear DNA.     

Characterization of monoclonal antibodies against prostate specific antigen produced by genetic immunization

Prostate specific antigen (PSA) is the most important marker for prostate cancer. Antibodies against minor variants of PSA may be useful in the development of novel diagnostic tests for prostate cancer, but it has been difficult to produce such antibodies by protein immunization. In this study, we have compared the characteristics of monoclonal antibodies (MAbs) obtained by genetic immunization with those obtained by protein immunization. The whole coding region of PSA-cDNA was cloned in a mammalian expression vector pCDNA-3. Six mice were immunized four times by intra-muscular (i.m.) injection of the PSA-pCDNA3 plasmid. The MAbs produced were characterized with respect to subclass, epitope specificity, binding to various molecular forms of PSA and affinity. After intra-muscular injection of DNA, anti-PSA antibodies were detected in the serum of all mice, but the antibody titers were markedly lower than after protein immunization. After fusion of the spleen cells from the mice, five hybridomas producing MAbs to PSA were obtained. The MAbs were of IgG1 and IgG2a isotype and they all recognized equally different forms of free PSA, namely enzymatically active, nicked and proPSA. Epitope mapping showed that these MAbs reacted with the same antigenic regions as those obtained by protein immunization. Thus, genetic immunization leads to production of anti PSA MAbs with similar characteristics to those obtained by immunizing with PSA protein. As applied in the present study, it is less efficient than protein immunization, but it is a useful technique when the antigen is not available in the quantities needed for immunization.     

特异性抗细胞表面分子单链抗体的分离和鉴定

目的：从抗KG1a细胞的噬菌体展示文库中分离和鉴定抗造血干/祖细胞表面分子单链抗体（scFv）,克隆其基因并研究其对应抗原在不同细胞表面的分布。方法：用完整的KG1a细胞吸附法富集文库3轮,再用CD44单克隆抗体为引导分子进行引导选择,分离单克隆后用间接免疫荧光法鉴别其细胞结合特异性。对具有不同细胞结合特异性的克隆进行DNA序列分析,用一级结构不同的单链抗体作免疫印迹鉴别抗原分子量。结果：间接免疫荧光结果显示,64个阳性克隆分别识别不同的细胞系,分属3种细胞结合谱,DNA序列测定结果证明C95、H1两个克隆具有独特的一级结构,利用Westernblot成功测定它们特异性识别KG1a细胞膜蛋白的表观分子量分别为34kD/22kD。结论：成功建立了分离和鉴定抗细胞表面分子phage-scFv单克隆的方法,并从抗KG1a细胞的噬菌体展示文库中分离出2个抗造血干/祖细胞的特异性克隆。     

Production of monoclonal antibodies against hepatitis B surface antigen (HBsAg) by somatic cell hybrids

Hybridomas secreting anti-HBs were produced by fusion of either adw or ayw HBsAg primed mouse spleen cells with either P3 X63 Ag8 or P3 NSI 1 Ag4 1 mouse myeloma cell lines. Individual anti-HBs secreting clones were isolated by limiting dilution procedures, and six cell lines have been established, namely, BX182, BX259, BX248, CN324, DN283, and DN296. Progenies of each cell line were derived from a single clone obtained from three subclonings of six anti-HBs positive initial fusion colonies. Clones were passaged in tissue culture and as tumors in syngeneic mice for upwards of six months. Anti-HBs of each line showed characteristic reactivity (detection) patterns in radio-immunoassay using different antigen subtype solid phases followed by either ¹²⁵I-HBsAg or ¹²⁵I-goat anti-mouse IgG probe. The specificity of the anti-HBs from each clone for the subdeterminants of HBsAg was identified by their reaction with ¹²⁵I-HBsAg ligands of several subtypes in a radioimmunoprecipitation assay. Four types of reaction were identified and correlated to the conventional serological subtyping definitions; they were anti-HBs/a (BX259 and CN324), anti-HBs/d (BX182), and possibly anti-HBs/w (BX248 and DN296) and anti-HBs/y (DN283). These monoclonal antibodies will be important for the elucidation of the antigenic structure of native HBsAg and will provide valuable reagents for both antigen detection and subtyping.     

Production and characterization of monoclonal antibodies against pigtailed macaque (Macaca nemestrina) cell adhesion molecules

Our previous in vitro studies indicate a significant role for cell adhesion molecules in the biology of HIV-1 and HTLV-1. Confirmation of the involvement of these molecules in the pathogenesis of retrovirus infection in vivo will require a suitable animal model. The SIV/pigtailed macaque (Macaca nemestrina) model of acquired immunodeficiency syndrome (AIDS) is an ideal system in which to study adhesion molecules and viral pathogenesis. The monoclonal antibodies (MAbs) against human adhesion molecules previously produced in our laboratory either do not react with or fail to block function of pigtailed macaque adhesion molecules. We have used papiovirus-transformed pigtailed macaque B cells as immunogen to generate murine MAbs against macaque adhesion molecules including ICAM-1, VCAM-1, and LFA-1. The specificity of the MAbs was confirmed by immunoprecipitation from lysates of vectorially iodinated cells, flow cytometry analysis of transfected cell lines and primary cells, binding assays on recombinant soluble human VCAM-1 and ICAM-1, and by inhibition of adhesion functions. MAbs against ICAM-1 and VCAM-1 showed positive staining of fixed tissue in immunohistochemistry studies. The same antibodies also blocked the function of these two adhesion molecules. The new MAbs can be used to study the tissue expression of adhesion molecules in SIV-infected animals as well as to test the involvement of these molecules in virus infection. Thus they should prove invaluable as probes of the role of cell adhesion molecules in AIDS pathogenesis in an animal model.