Bispecific antibody-producing hybrid hybridoma and its use in one-step immunoassays for human lymphotoxin

A hybrid hybridoma cell line secreting a bispecific monoclonal antibody (MAb) was constructed by fusing horseradish peroxidase (HRPO)-immunized mouse splenocytes with previously established mouse hybridomas secreting anti-human lymphotoxin (hLT). This cell line was grown in ascitic fluid in mice to obtain large quantities of hybrid MAbs and a bispecific antibody, reacting with both HRPO and hLT, was separated from the monospecific antibody or other inactive immunoglobulin populations by hydroxylapatite chromatography. Sodium dodecylsulfate-polyacrylamide gel electrophoresis demonstrated that the bispecific antibody molecule contained two different types of heavy and light chains of both anti-HRPO and anti-hLT origin. The bispecific antibody was used to establish one-step enzyme immunoassays (EIAs) employing competitive and sandwich systems. The simple sandwich EIA was able to detect 1-100 U/ml of hLT and there was good correlation (r = 0.96) between hLT concentrations measured by the one-step EIA and a bioassay using L929 cell-lysis.     

Production and ELISA application of bispecific monoclonal antibodies against fluorescein isothiocyanate (FITC) and horseradish peroxidase (HRP)

Hybrid hybridomas producing bispecific monoclonal antibodies reacting with both horseradish peroxidase (HRP) and fluorescein isothiocyanate (FITC) were obtained by fusing two hybridoma lines and selecting the fused cells using a fluorescence activated cell sorter (FACS). FITC was used to label different monoclonal antibodies and the bispecific antibodies acted as a linking agent between FITC-labelled antibody and the marker enzyme HRP. This system was used in enzyme immunoassays for the detection of different antigens. The results suggest a wide application of bispecific anti-FITC/anti-HRP antibodies as a detection system in EIA.     

Quadroma-secreted bi(interferon alpha 2--peroxidase) specific antibody suitable for one-step immunoassay.

A mouse hybridoma (quadroma) was prepared by fusing hybridomas producing monoclonal antibody of G1-isotype to human interferon-alpha 2 with hybridomas producing monoclonal antibody of G2a-isotype against horseradish peroxidase. The established quadroma line secreted immunoglobulins of both G1/G2a-isotypes which manifested parental and bispecific binding characteristics. Culture supernatant containing the bifunctional antibody cross-linking interferon and peroxidase was used for a one-step immunoassay. The developed sandwich ELISA was able to detect the human interferon-alpha 2 at a concentration of 10 units/ml (0, 1 ng/ml) within 2-3 hours.     

Selection of hybrid hybridomas by flow cytometry using a new combination of fluorescent vital stains.

A new combination of fluorescent dyes (rhodamine 123 and hydroethidine) was used to internally label hybridoma fusion partners. Murine hybridoma 520C9 (recognizing human c-erbB-2) was labeled with hydroethidine. Murine hybridoma 3G8 (recognizing human Fc gamma receptor III) was labeled with rhodamine 123, and verapamil was used to block rhodamine efflux via P-glycoprotein. Viability assays showed little cytotoxicity from these dyes at the concentrations used. The labeled cells were fused with polyethylene glycol, sorted for dual fluorescence on an Epics V cell sorter, and cloned. Hybrid hybridomas producing bispecific antibodies were selected for ability to promote lysis of SK-Br-3 breast cancer cells by human mononuclear cells. Several positive clones were obtained and shown to have a double content of DNA. Bispecific antibody produced by subclone 2B1 was purified by anion exchange chromatography and shown to bind both tumor cells and Fc gamma R III bearing cells. Using two parameter flow cytometric analysis, we were able to measure a 'bridging' effect of this bispecific antibody, which caused formation of complexes between PMNs and SK-Br-3 cells. Either parental antibody could compete with bispecific antibody to block such complexing. This fusion method provides several advantages over other techniques presently used (speed, convenience, low toxicity and automatic exclusion of dead cells) and can be applied to produce other hybrid hybridomas.     

IgG型抗CD55×抗β-Gal基因工程双特异性抗体的构建

目的　探讨用生物学方法治疗病毒感染性疾病及肿瘤的新途径。方法　以有重要补体活化调节功能的膜补体调节蛋白CD5 5为靶点 ,以 β GaL为模拟病毒或肿瘤抗原 ,制备“IgG”型抗CD5 5×抗 β Gal基因工程双特异性抗体 ,并对该重组抗体真核表达后的结合活性进行初步的验证。结果　克隆的CD5 5抗体可变区片段为新的小鼠抗体可变区片段 ,经HEK 2 93细胞表达后的重组抗体显示了良好的CD5 5及Fc结合活性。结论　本研究为病毒性疾病或肿瘤的免疫学治疗提供了新的途径及实验依据     

Antigen binding properties of highly purified bispecific antibodies.

A panel of three bispecific monoclonal antibodies (bsMAbs) binding to follitropin (FSH) and to beta-galactosidase have been prepared by fusion of hybridoma cell lines resistant to oubain and neomycin. One of these bispecific antibodies contains heavy chains of the same IgG subclass, and two are composed of heavy chains of different IgG subclasses. We have investigated methods for the purification of bispecific antibodies from hybrid hybridoma supernatant fluids grown in serum-free medium. Following ammonium sulfate precipitation, bispecific antibodies can be purified in a single step by mixed mode ion-exchange HPLC on Bakerbond Abx columns. In one case, three species were resolved by ion-exchange HPLC and functional analysis showed that two peaks contained parental antibodies, and the third contained the bispecific. Ion-exchange HPLC purification of serum-free preparations from two other hybrid hybridomas resolved seven protein-containing peaks, only one of which was active in a bispecific ELISA. The equilibrium affinity constants for each of the parental antibodies for both FSH and beta-galactosidase were determined and found to be similar to those of the purified bsMAbs. Further, the association of FSH to one binding site on a bispecific antibody was shown to have no effect on the equilibrium binding constant for beta-galactosidase binding to the other site. Our results suggest that bsMAbs can be readily purified from hybrid hybridomas by a simple and rapid method, and the binding of antigen to one binding site on a bsMAb is independent of antigen binding to the second site.     

Monoclonal antibody production by hybridoma growth in Freund's adjuvant primed mice

Incomplete Freund's adjuvant was used as a priming agent prior to the injection of hybridoma cells in mice to expand monoclonal antibody production. Two hybridoma cell lines, FDO28B (IgG1) and FDO31C (IgM), which produce monoclonal antibodies reactive towards human placenta, were used. Monoclonal antibody was detected in the ascites fluids by agarose gel electrophoresis. It was found that the time interval between adjuvant priming and cell injection could be reduced to 1 day, allowing collection of ascites fluid containing monoclonal antibody within 2 weeks of priming. In addition, as few as 1 X 10(5) hybridoma cells were needed to collect approximately 5-7 ml of ascites fluid containing antibody detectable by gel electrophoresis. Thus priming with incomplete Freund's adjuvant enables production of large amounts of monoclonal antibody in a short time using a low number of hybridoma cells.     

Function of idiotypic networks in vivo: immunisation with idiotype-bearing (Id1) antibody induces further production of Id1 antibody.

Injection of BALB/c mice with an anti-foot-and-mouth disease virus (FMDV) monoclonal antibody (mAb) apparently induced the idiotype network to produce more anti-FMDV (idiotype-bearing) antibody, as determined by hybridoma production. Anti-idiotype antibodies were also induced, detected by binding directly to the mAb used for the immunizations (the "immunising" antibody). Many of the anti-idiotype antibodies were directed against regions in or near the paratope of the immunising mAb, since they competed for the binding of the latter mAb to 146S antigen. The induced idiotype-bearing (anti-FMDV) antibodies also competed for the binding of the immunizing mAb to 146S antigen, demonstrating that both antibodies were of similar epitope specificity. Consequently, it would appear that an idiotype-bearing (Id1) antibody can induce the idiotypic networks to produce more Id1 antibody of the same specificity as that used for the initial stimulation, demonstrating the in vivo functioning of the idiotype network.     

Production and use of rat monoclonal antibodies to the human myeloid cell nuclear differentiation antigen

A dot immunoblot screening assay was used to identify rat monoclonal antibodies to a human myeloid cell differentiation-specific nuclear antigen (MNDA). The selection was based on the positive reaction of hybridoma cell supernatants with a concentrated nuclear protein extract prepared from late stage human myeloid leukemia cells that express MNDA (HL-60) coincident with a negative reaction with the same extract prepared from a non-expressing more immature human myeloid leukemia cell line. The approach provided an efficient method for obtaining monoclonal antibodies to a specific low abundance nuclear antigen that has not been purified. Sixteen wells from three fusions contained antibody displaying a specific reaction with the nuclear protein fraction obtained from the HL-60 cells. Immunoblotting analysis revealed that all of the sixteen specific hybridoma cell lines produced antibody against the same Mr 55,000 nuclear antigen. Selecting hybridoma cells that produce antibody reactive with the native antigen provided antibody suitable for detecting MNDA in immunocytochemical tests. The rat monoclonal antibodies were purified and coupled to CNBr-activated agarose and carbonyldiimidazole-activated agarose. Although both antibody affinity matrices exhibited the same antigen binding capacities, the matrix prepared using carbonyldiimidazole-activated agarose bound the MNDA with a high level of specificity while the matrix prepared from CNBr-activated agarose bound numerous other nuclear proteins.     

Use of bispecific antibodies in molecular velcro assays whose specificity approaches the theoretical limit of immunodetection for Bordetella pertussis

A bispecific monoclonal antibody (bsMAb) that detects Bordetella pertussis, the causative agent of whooping cough, and horseradish peroxidase (HRPO) has been developed by use of the quadroma technology. A quadroma, P123, was produced by fusing two well-characterized hybridomas against the bacterium and the enzyme and was subcloned to obtain a stable bsMAb-secreting cell line. The quadroma was theoretically expected to produce up to 10 different molecular species of immunoglobulins, so secreted bispecific antibody was complexed with excess HRPO and the HRPO-bsMAb complex was purified in one step by benzhydroxamic acid-agarose affinity cochromatography. An ultrasensitive homosandwich molecular "velcro" enzyme-linked immunosorbent assay for the detection of B. pertussis whole bacteria with HRPO-bsMAb was established in both microplate and nasopharyngeal swab formats. This assay demonstrates a high sensitivity that approaches the theoretical limit of detection of one bacterium. This new nanoprobe can be used to develop a new generation of assays that are simple, inexpensive alternatives to quantitative PCR and that can be used by clinical laboratories. This strategy of homosandwich assays with solid-phase monospecific antibodies and solution-phase bsMAb with specificity for the same repeating surface determinants can be applied to generate ultrasensitive immunodiagnostic assays for viruses and bacteria.     

A general affinity method to purify peroxidase-tagged antibodies

Antibodies tagged with enzymes, e.g. horseradish peroxidase (HRPO) are used extensively in a broad range of immunoassay, immunohistochemical, and prodrug-based immunotherapeutic applications. These antibodies may be polyclonal, monoclonal, bispecific or genetically engineered in origin. Often, purification of the antibody is the single greatest obstacle to obtaining immunoprobes with high specific activity [Milstein and Cuello, Nature 305 (1983) 537]. We have circumvented this problem by utilising benzhydroxamic acid-agarose to purify the antibodies tagged with HRPO as a preformed immune complex. Benzhydroxamic acid has been shown to have affinity for the active site of HRPO [de Ropp et al., Biochemistry 38 (1999) 1077]. A preliminary ammonium sulfate precipitation of 250 ml of bispecific antibody supernatant was performed and the pellet resuspended and dialysed against phosphate buffer (pH 7.0). This fraction was incubated with HRPO, then loaded on the affinity column which was washed, and the labelled bispecfic monoclonal antibodies were eluted under mild conditions (borate buffer pH 9.0). The effective yield of this bispecific antibody-HRPO complex was 30 assay plates or 3000 wells. We have also successfully co-purified covalent polyclonal-HRPO conjugates and HRPO-labelled streptavidin using a similar strategy to obtain enzyme-labelled probes with high specific activities for a multitude of applications.     

Annexin A2单克隆抗体制备及初步鉴定

制备Annexin A2特异性单克隆抗体(McAb),为Annexin A2的体内外功能的研究提供有力的抗体工具。以原核表达的全长p36蛋白(Annexin A2单体)免疫BALB/c小鼠,通过杂交瘤技术制备针对Annexin A2的McAb。以间接ELISA法筛选出目的杂交瘤细胞株并进行染色体计数;分析McAb的亚型,检测其效价、浓度及亲和常数;以细胞荧光染色,Western blot和RT-PCR鉴定McAb特异性。结果得到1株能稳定分泌特异性针对p36的McAb的细胞株F8,其抗体亚类重链为IgG2a,轻链为κ型;腹水纯化后效价为1∶4 000;亲和常数为3.4×109L/mol。成功获得了能稳定分泌AnnexinA2特异性McAb的细胞株。     

人白细胞介素15单克隆抗体的制备及鉴定

目的 :用rhIL 15与沙门氏菌裸菌相偶联制备IL 15单克隆抗体 (monoclonalantibody ,McAb) ,以便为疾病的诊断、治疗和发病机制的研究提供可靠的生物制剂。方法 :将纯化的rhIL 15蛋白与沙门氏菌裸菌相偶联制成免疫原 ,用脾内、腹腔、静脉三种途径相结合免疫BALB c小鼠 ,以PEG为促融剂 ,将脾细胞与SP2 0细胞进行融合 ,HAT选择培养 ,间接ELISA筛选阳性克隆 ,通过多次克隆化 ,获得稳定分泌特异性McAb的杂交瘤细胞株 ,并对所获得的细胞株及分泌的McAb特性进行了分析。结果 :获得 4株能稳定分泌特异性McAb的杂交瘤细胞系 (hybridomacell,Hc) ,ELISA法检测其效价分别为 1:10 6 、1:10 7、1:10 7、1:10 7。Dotblot检测IL 15的灵敏度为 1 5ng ,其中一株 (1 7E4 )尚可用于Westernblot检测。结论 :成功制备了 4株IL 15McAb杂交瘤细胞系。     

抗人内皮细胞特异性分子-1单克隆抗体的研制和初步鉴定

运用B淋巴细胞杂交瘤技术 ,以人内皮细胞特异性分子 1(ESM 1)蛋白为抗原 ,经PEG融合 ,有限稀释法筛选 ,获得了 7株稳定分泌抗人ESM 1的杂交瘤细胞株 ,其中 3A7细胞株特异性尤为显著 ,效价高达 1∶6 0 0 0。所分泌抗体亚型为IgG2b ,Westernblot结果表明对内皮细胞中的ESM 1蛋白及细胞培养上清中的ESM 1均可特异性识别。并观察到ESM 1主要分布在内皮细胞的细胞胞质伴胞核中。在肾组织中 ,ESM 1定位于血管内皮细胞 ,且肾癌标本中ESM 1阳性表达显著高于正常肾组织。免疫组化结果表明所获单抗具有一定的特异性和实用性。     

One-step method for establishing 8-azaguanine-resistant hybridomas suitable for the preparation of triomas.

A simple and rapid one-step method for establishing azaguanine resistant (Agr) hybridomas, which can be used as a fusion partner for the construction of triomas (hybridoma x splenocyte), has been developed. The method relies on cloning the hybridoma cells in soft agar supplemented with 20 micrograms/ml 8-azaguanine. The drug-resistant subclones were isolated after 3-5 days, in comparison with 4-5 weeks reported for the conventional adaptation method. The high frequency (about 10(-3) of Agr-mutants achieved by the cloning method was demonstrated with five different hybridoma clones. One of the derived Agr-hybridomas was fused with mouse immune spleen cells in order to demonstrate its suitability for the generation of triomas secreting bispecific monoclonal antibodies.     

抗HIV p24和人A型红细胞双特异性单克隆抗体的研制

目的：制备抗HIV p24和人A型红细胞双特异性单抗(mAb)，并建立检测HIV p24的间接血凝试验。方法：将分泌抗HIV p2d mAb的杂交瘤株2-E4和分泌抗人A型红细胞mAb的杂交瘤株S2，分别用8-Ag和5-BrdU驯化，使成为HAT敏感株。将两者常规融合，筛选分泌双特异性mAb的杂交-杂交瘤株。然后制备并纯化双特异性mAb，用其建立的间接血凝法检测p24。结果：共获得6株杂交-杂交瘤细胞株，以其分泌的双特异性mAb建立了检测HIV p24的间接血凝法，敏感性可达400ng/L。结论：获得可稳定分泌双特异性mAb的杂交-杂交瘤株，并用纯化的双特异性mAb建立了快速检测HIV p24的间接血凝法。     

Flow sorting of hybrid hybridomas using the DNA stain Hoechst 33342

A two-step sorting procedure with the fluorescence-activated cell sorter (FACS) is described for the selection of hybrid hybridomas producing bispecific monoclonal antibodies. Parental hybridoma cells were first labelled before fusion with fluorescein isothiocyanate (FITC) and tetramethyl rhodamine isothiocyanate (TRITC); heterofluorescent cells were recovered after fusion. After a period of growth in culture, the cells were then stained with the DNA-specific dye bis-benzimidazole Hoechst 33342 and sorted on the basis of their DNA content. The staining conditions (10 micrograms/ml of Hoechst 33342, 90 min incubation time at 37 degrees C) were found to be optimal for obtaining a well resolved DNA histogram with minimal effect on the growth properties of cells from different mouse hybridoma lines. Employing this method we have isolated hybrid hybridomas synthesizing bispecific monoclonal antibodies reacting with human low density lipoprotein and alkaline phosphatase from calf intestine.     

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.     

Bispecific anti-human red blood Rhesus-D antigen x anti Fc gamma RI targeted antibody-dependent cell-mediated cytotoxicity and phagocytosis by mononuclear leucocytes.

The Fc receptor mediated antibody-dependent cell-mediated cytotoxicity (ADCC) and phagocytosis induced by bispecific antibody (BsAb) to the high-affinity Fc receptor for IgG (Fc gamma RI) and to human red blood group antigen RhD were studied in vitro, using human mononuclear leucocytes as effector cells. The results were compared with those obtained by using a human monoclonal IgG1 anti-RhD used alone and a reference human polyclonal anti-RhD antibody. The effect of non-specific human IgG on FcR-mediated functions by mononuclear leucocytes was checked. The results demonstrate that BsAb presents a high resistance of Fc-mediated function to blockade by non-specific human IgG compared with that of both polyclonal and monoclonal anti-RhD antibodies. These results further encourage possible clinical application of bispecific antibody in passive immunotherapy.     

Restoring antibody activity of a monoclonal anti-RNP antibody by dissociative HPLC. Demonstration of blocking antibody binding sites with antigen released from effete hybridoma cells.

In biomedical research, monoclonal anti-nuclear antibodies have a number of advantages over polyclonal antibodies in terms of both specificity and reproducibility. However, there are some potential problems in the preparation of monoclonal antibodies. A well characterized mouse monoclonal anti-ribonucleoprotein antibody (anti-RNP antibody, 2.73) known to function in Western blotting was found to lose this activity when produced in vitro from long term hybridoma cell culture. Whilst it could no longer detect RNP antigen by Western blotting, it could still function effectively in affinity purification of RNP antigen. Further studies suggested that this was due to blocking of antibody binding sites by RNP antigen released from effete hybridoma cells in culture. The activity of the antibody in affinity purification was retained because the antigen was stripped away by repeated elutions with 6 M urea. HPLC gel filtration in the presence of 6 M guanidine was able to restore the antibody activity of the protein A purified monoclonal antibody. This finding has important general consequences for the preparation of monoclonal antibodies against antigens present in hybridoma cell culture media.