Cellular localization of insulin-degrading enzyme in rat liver using monoclonal antibodies specific for this enzyme

Although insulin-degrading enzyme (IDE) has been implicated in the intracellular degradation of insulin, the cellular localization of this enzyme is still controversial. In the present study, we have examined the cellular localization of IDE in the rat liver by three different techniques using monoclonal antibodies. First, direct immunohistochemical staining of rat liver with one of the monoclonal antibodies revealed that IDE immunoreactivity mainly exists in parenchymal cells, especially in the vicinity of the portal tract and also in the epithelium of the bile duct under light microscopy. In the electron microscopic study, IDE immunoreactivity was found in the cytoplasm near the rough endoplasmic reticulum but not in the plasma membrane, nucleus, or mitochondria. Second, immunoblotting analysis of the subcellular fraction in rat liver showed that the monoclonal antibody specifically reacted with a single polypeptide in the cytosolic fraction, of apparent Mr 110,000, which was consistent with the Mr of IDE. However, a polypeptide band corresponding to IDE could not be observed in the plasma membrane, mitochondrial, or lysosomal fraction. Third, IDE was only detectable in the cytosolic fraction by sandwich radioimmunoassay using two monoclonal antibodies. These results all suggest that IDE is a cytosolic enzyme.     

Expression and purification of the outer shell proteinVP2 of the 4th serotype Bluetongue virus,and preparation of monoclonal antibodies against this protein

Bluetongue (BT) is an arbovirus transmitted disease by bites of the genus Culicoides and infects wild and domestic ruminants particularly in sheep. As an important outer shell protein which defines BTV serotypes, VP2 has been shown to be an ideal target antigen for identification of different BTV serotypes. In order to prepare a monoclonal antibody (mAb) against the VP2 protein of BTV-4, the corresponding encoding gene L2 was divided into three segments and then cloned into pET-28a (+) and pMAL-c5X vectors to generate recombinant plasmids, which were expressed in Escherichia coli BL21 (DE3) as histidine (His)-tagged (His-4A/4B/4C) and maltose-binding protein (MBP)-tagged (MBP-4A/4B/4C) fusion proteins. After affinity purification of His-4A/4B/4C with Ni-NTA agarose and MBP-4A/4B/4C with amylose resin, His-4A/4B/4C were used to immunize BALB/mice and MBP-4A/4B/4C were used to screen for mAb-secreting hybridomas. Five hybridoma cell lines stably secreting mAbs against different VP2 segments were obtained, in which 4A-1G7 and 4B-1B6 could recognize BTV-4 and also cross-react with other BTV serotypes. With the joint action of the two mAbs, BTV-4 and BTV-20 infection would be distinguished from other BTV serotypes. The successful preparation of recombinant VP2 segments and mAbs provides valuable materials that can be used in serological diagnosis of BTV-4.     

The use of monoclonal antibodies against insulin for isolation of proteins inhibiting the cell growth

Extracts of pig kidneys or germinated soya beans after preliminary steps were affinity chromatographied on Sepharose containing cyanogen bromide immobilized monoclonal antibodies to pig insulin. The material bound to the affinity column was separated by HPLC resulting in one homogeneous protein from each source. Both proteins have been shown to inhibit DNA synthesis in cultured embryonic human fibroblasts and VERO fibroblasts. The effect of pig kidney protein was potentiated by insulin. Soya and pig proteins were characterized by the following parameters: molecular weights of 8.5 and 10.3 kD, apparent constants of dissociation with rat liver plasma membranes of 4.7 x 10(-8) M and 9.8 X 10(-8) M, respectively. The soya proteins competed for the binding sites on plasma membranes with insulin whereas the pig protein did not. The N-terminal amino acid sequences of 20 residues were determined for both proteins. Comparison of these sequences with known protein sequences was performed. A 30-40% primary structure homology of the studied fragment of soya bean protein with the fragments of some oncogenic viruses proteins and transforming proteins was revealed.     

Production of monoclonal antibodies against avidin

Monoclonal antibodies of the IgG1 subclass were generated against chicken avidin. These antibodies were shown to be as sensitive as polyclonal antiserum in detecting avidin by radioimmunoassay (RIA) and enzyme linked immunosorbent assay (ELISA) methods. Furthermore, the monoclonal antibodies were considerably more specific. Our results with a monoclonal anti-avidin RIA support previous findings that in inflammatory conditions avidin is synthesized also in other organs than the oviduct, although in the liver a major part of the activity detected by polyclonal anti-avidin RIA or biotin-bentonite assay was not due to avidin.     

Polyclonal antibodies against RNase L. Subcellular localization of this enzyme in mouse cells.

RNase L activated by 2-5A (a series of 2'-5'-linked adenylic oligoribonucleotides) is a key enzyme of the interferon system. To study RNase L (endonuclease L) in intact cells independently of intracellular 2-5A and of its activity, we have developed polyclonal antibodies against RNase L. RNase L from mouse spleen was purified on a column of 2-5A-Sepharose and used to immunize rabbits in co-injection with polyadenylic-polyuridylic acid as adjuvant. Antibodies were purified by chromatography on Affi-Gel blue and 2-5A-Sepharose-immobilized RNase L. These polyclonal antibodies immunoprecipitate the 80- and 40-kDa forms of RNase L in mouse spleen. In Western blot, only the 80-kDa form of RNase L is recognized by these antibodies. These purified antibodies were used to localize RNase L in the cytoplasm of intact mouse NIH 3T3 cells by immunofluorescence. The cytoplasmic localization of RNase L was confirmed by its 2-5A binding activity after cellular fractionation.     

Use of monoclonal antibodies against horse immunoglobulin in an enzyme immunoassay of bacterial toxins and anatoxins

Immunization of BALB/c mice by horse antiserum against diphtheria made it possible to obtain IgG1 monoclonal antibodies (MoAbs) 2B7E4 specific for light chains of horse immunoglobulin (Ig). Unlike commercial preparations of anti-horse immunoglobulin antibodies, which are specific for the whole Ig molecule or its Fc-fragment, the peroxidase (HRP) conjugate of the MoAb, 2B7E4-HRP did not interact with human, mouse, rabbit, and sheep Igs, or horse albumin. The conjugate obtained was used with MoAbs against bacterial toxins and commercial horse anatoxins, as a universal reagent in sandwich enzyme immunoassay (ELISA) for bacterial toxins and anatoxins. The detection sensitivity of diphtheria toxin/anatoxin equaled 0.0005 Lf/ml; tetanus toxin and anatoxin were detected with sensitivities of 20 LD50/ml and 0.005 UI/ml, respectively. A similar sandwich ELISA for botulinum anatoxins (group measurement) allowed types A, B, and E to be detected at 0.02, 0.002, and 0.001 UI/ml, respectively; selective measurement was only possible in the case of type E anatoxin (0.001 UI/ml).     

Use of monoclonal antibodies against horse immunoglobulin in an enzyme immunoassay of bacterial toxins and toxoids

Immunization of BALB/c mice by horse antiserum against diphtheria made it possible to obtain IgG₁ monoclonal antibodies (MoAbs) 2B7E4 specific for light chains of horse immunoglobulin (Ig). Unlike commercial preparations of anti-horse immunoglobulin antibodies, which are specific for the whole Ig molecule or its Fc-fragment, the peroxidase (HRP) conjugate of the MoAb, 2B7E4-HRP did not interact with human, mouse, rabbit, and sheep Igs, or horse albumin. The conjugate obtained was used with MoAbs against bacterial toxins and commercial horse antitoxins, as a universal reagent in sandwich enzyme immunoassay (ELISA) for bacterial toxins and toxoids. The detection sensitivity of diphtheria toxin/toxoid equaled 0.0005 Lf/ml; tetanus toxin and toxoid were detected with sensitivities of 20 LD₅₀/ml and 0.005 UI/ml, respectively. A similar sandwich ELISA for botulinum toxoids (group measurement) allowed types A, B, and E to be detected at 0.02, 0.002, and 0.001 UI/ml, respectively; selective measurement was only possible in the case of type E toxoid (0.001 UI/ml).     

抗磺胺对甲氧嘧啶单克隆抗体的研制及其特性分析

目的制备针对磺胺对甲氧嘧啶的单克隆抗体,建立对该物质的免疫学检测方法。方法以BSA-磺胺对甲氧嘧啶为免疫原,免疫BALB／c小鼠,取脾细胞与小鼠Sp-2／0骨髓瘤细胞融合后,经筛选和亚克隆,建立杂交瘤细胞株。结果获得2株能稳定分泌抗磺胺对甲氧嘧啶抗体的细胞株。对抗体进行了特性分析,抗体的效价分别为1：400000和1：1630000,抗体类型及亚类都为IgGl。其中,单克隆抗体1H10的亲和力为1．4×109L／mol,利用该抗体采用竞争间接ELISA法检测磺胺对甲氧嘧啶的范围是1025—16μg/mL,最低检测浓度是8μg/mL。单抗1H10与其他6种磺胺药（SMM、SMZ、SM2、SD、SulfaquinoxalineSodium、Sulfametetyrazine）无交叉反应。结论单克隆抗体1H10可用于研制免疫学方法检测磺胺对甲氧嘧啶残留的产品。     

Human alfa-fetoprotein: isolation and production of monoclonal antibodies.

Alfa-fetoprotein from human cord serum was purified in a single step by hydrophobic interaction chromatography on Phenyl Sepharose CL-4B with a final recovery of alfa-fetoprotein of about 90% and a purification factor of 900. The purified preparation was homogeneous on SDS-PAGE and native PAGE running with a relative molecular weight of 72,000. Monoclonal antibodies against this purified preparation were raised by hybridoma technology using Sp2/0 myeloma cells as a fusion partner. 50% of culture wells exhibited hybrid growth and 7% of these wells contained anti-AFP secreting hybrids. Positive hybrid cells were cloned twice by the limiting dilution method and 8 clones were obtained that secreted monoclonal antibodies. Five of these cell lines (3F6H10, 3F6H4, 3F6H1, 3F6G5 and 3F6G10) were selected at random for purification and characterization purposes. All 5 cell lines secreted monoclonal antibodies of IgG1 subclass which were purified by affinity chromatography on Protein A- Sepharose CL-4B column with a final recovery of 80% and a purification factor of about 13. The purified preparations were homogeneous on SDS-PAGE, native PAGE and IEF. The monoclonal antibodies were highly specific for human alfa-fetoprotein as determined by Western blotting. The affinity constants (K) of these Mab ranged from 10(6) to 10(9) l/mol.     

A highly sensitive and convenient method to detect monoclonal antibodies against acetylcholine receptors

Three methods were compared for detecting monoclonal antibodies against Narke japonica acetylcholine receptors as to the sensitivity of the detection and the convenience of operation. One of the methods involves the use of a microplate lid with 96 attached plugs that are immersed into opposite wells, and requires very simple operations. This method was found to be highly sensitive and could detect specific antibodies at levels of less than 150 pg/ml in the culture medium of hybridoma cells.     

Preparation and purification of monoclonal antibodies against chloramphenicol

Monoclonal antibodies (McAbs) against chloramphenicol (CAP) were produced to detect CAP residues, which could be toxic and possesses a potential threat to human health. The CAP-BSA conjugate was obtained by bovine serum albumin (BSA) coupled with CAP, and used to immunize the mice. The splenocytes from the immunized mice were fused with mouse myeloma cells SP2/0 to form hybridoma, which may secrete McAbs against CAP. Hybridomas 1D₁ and 3G₁₂ secreting McAbs against CAP were obtained by screening. Ascites containing McAbs were prepared by injecting 1 x 10⁶ cells of hybridoma 1D₁ and 3G₁₂ into the abdomen of mice. Protein A affinity chromatography was used to purify McAbs against CAP in a single chromatographic step with recovery yield above 80% and purity above 95% and full recovery of antibody activity. Experiments showed that McAb 3G₁₂ was highly specific for CAP and had no cross-reactivity with analogues which have a structure similar to CAP. The IC₅₀ value was 50.8 ng/mL.     

Solid-phase enzyme immunoassay of urokinase using monoclonal antibodies

Using two monoclonal antibodies directed against urokinase, we have developed a micro enzyme-linked immunosorbant assay (ELISA) to detect and measure urokinase in biological fluids. The system presents the following characteristics: simple and rapid procedure, reproducibility, sensitivity (urokinase levels down to 1 ng/ml) and evaluation of the enzyme in biological fluids such as urine, pleural effusions, and ascitic fluids without preliminary purification.     

Transfer of monoclonal antibodies into mammalian cells by electroporation

A simple rapid and reproducible procedure for transferring monoclonal antibodies into mammalian cells by electroporation is described. Two functionally different monoclonal antibodies (Mab 3F3 and Mab 2B4) specific for asparagine synthetase (EC 6.3.1.1) were used for electroporation into HeLa, HT-5, and L5178Y D10/R (L-asparaginase-resistant) cells. The conditions were optimized so that the viability of the electroporated cells was very high (80-90%), and 90% of the viable cells had antibody incorporated. Electropermeabilized cells were structurally intact, and the high voltage electric pulse had no inhibitory effect on overall cellular DNA and protein synthesis. Incorporated immunoglobulins showed unaltered structural integrity and were functionally active. L5178Y D10/R cells incorporated with an antibody (Mab 3F3) known to be a potent inhibitor of tumor asparagine synthetase showed increased dependence on an exogenous source of asparagine in the culture medium, while the growth of cells incorporated with a control (noninhibitory) antibody (Mab 2B4) remained unaffected. These studies demonstrate that electroporation can be employed successfully for large scale transfer of antibodies into cultured mammalian cells for the study of cellular metabolism.     

The isolation of monoclonal antibodies to Cryptococcus neoformans antigens

In this work conditions for the reproduction of hybridoma technology, specially adapted to C. neoformans, for obtaining monoclonal hybridomas (McAb) to diagnostically significant antigens of C. neoformans, the infective agent of cryptococcosis, are presented. The advantages of using the short-time cycle of stimulation of mouse B lymphocytes with low doses of C. neoformans capsular polysaccharide and the effectiveness of the hybridization of mouse spleen cells with myeloma cells, line Sp2/0, are shown. Four lines of stable hybridomas, producing McAb to different epitopes of C. neoformans surface antigens, have been obtained. The specific activity of McAb has been studied in the indirect immunofluorescence assay, the cytochemical and solid-phase enzyme immunoassays (EIA). McAb 3E2, Cr2 and 2G9 have been shown to be suitable for use in diagnostic EIA systems.     

抗酸土脂环酸芽孢杆菌(Alicyclobacillus acidoterrestris)单克隆抗体制备

【背景】基于本实验室已经建立的脂环酸芽孢杆菌检测和鉴定方法工作基础之上,以期建立具有很好的经济价值和实用价值,且更为方便、快捷、准确、特异、灵敏的检测方法。【目的】实现对果汁生产中脂环酸芽孢杆菌从原料到成品的快速检测和鉴定。【方法】采用杂交瘤细胞技术,以Alicyclobacillus acidoterrestris(ATCC49025)免疫BALB/c小鼠,用建立的间接ELISA方法筛选杂交瘤细胞,得到了3株能稳定分泌A.acidocaldarius抗体的杂交瘤细胞株,其中两株为Ig G1亚类,并对其进行生物学特性的鉴定。【结果】得到的两株单抗3F7和9C4是针对不同的抗原位点,且多次传代后稳定性基本保持不变;特异性实验表明两株单抗均不与A.acidocaldarius(NCIMB11725)、Bacillus cereus(ATCC11778)、Bacillus subtilis(ATCC11774)、A.cycloheptanicus(ATCC49029)等发生交叉反应。【结论】3F7和9C4这两株单抗可以进一步用于检测胶体金试纸条的研制。     

Characteristics of monoclonal antibodies against Lassa virus

Some properties of monoclonal antibodies to the Lassa virus have been characterized. The competitive immunoenzyme analysis has revealed the presence of at least three antigens in the Lassa virus nucleoprotein.     

The production of monoclonal antibodies against aldosterone

We have prepared several monoclonal antibodies against aldosterone-3-carboxy-methyloxime-BSA conjugate by fusing spleen lymphocytes from an immunized mouse with the mouse myeloma line HL-1 Friendly. A total of 6 different clones were isolated and expanded. All of the antibodies exhibited low cross-reactivities against most of the compounds tested. Antibodies A5A3, A2E11, and C1E2 exhibited low cross-reactivity with 18-hydroxycorticosterone and 18-hydroxydeoxycorticosterone and showed no detectable displacement of tritiated aldosterone from the antibodies with cortisol, corticosterone, and related steroids. The only steroid that showed moderate cross-reactivity was 3 alpha,5 beta-tetrahydroaldosterone (around 3%). Clone A5H12 antibodies exhibited high cross-reactivity with tetrahydroaldosterone (19.3%) but otherwise was very similar to the above clones. Antibody of clone C1E4 showed high cross-reactivity to tetrahydroaldosterone (41.2%) and 18-hydroxyDOC (2%) with relatively low cross-reactivity to DOC (0.078%). Clone A2G9 antibodies were the only ones for which cortisol and corticosterone displaced tritiated aldosterone with cross-reactivities of 0.0042% and 0.125%, making them unsuitable for a direct radioimmunoassay of plasma aldosterone. The monoclonal antibodies were very sensitive to freezing and thawing. The cross-reactivities of the first three clones' antibodies compare favorably with those polyclonal antibodies that have been described to be suitable for use in direct radioimmunoassays of plasma aldosterone. Their advantage is the reliable supply of an antibody with consistent, predictable properties.     

Characterization of monoclonal antibodies against Gnathostoma nipponicum

Monoclonal antibodies (mAbs) were produced against the proteins of advanced third-stage larvae (AdL3) of Gnathostoma nipponicum. Six mAbs (Gn2C3, Gn2H3, Gn4C3, Gn4E9, GnSH1, and Gn10B7) were obtained as determined by enzyme-linked immunosorbent assay (ELISA). Gn4E9 and GnSH1 seemed to be genus-specific, as they did not cross-react with Anisakis sp., Dirofilaria immitis, Gongylonema pulchrum, Toxocara canis, Trichinella sp., Trichuris vulpis, Metagonimus sp., or Spirometra erinaceieuropaei by ELISA. Immunohistochemistry showed that Gn2C3, Gn4E9, and Gn5H1 reacted strongly with the central esophagus; Gn2H3 reacted with cuticle,muscle, intestine, and the cervical sac; and Gn4C3 and Gn10B7 reacted with cuticle, muscle, esophagus, intestine, and the cervical sac of AdL3. In Western blotting analysis, Gn2C3, Gn4E9, and Gn5H1 reacted to 60-, 53-, 46-, and 41-kDa proteins; Gn4C3 reacted to the AdL3 protein of G. nipponicum (>42 kDa). Moreover, proteins purified using a mAb Gn4E9 immunoprecipitation method (sizes 60-, 53-, 46-, and 41-kDa) were used as antigens in ELISAs. A significant difference (P < 0.01) was shown between mouse sera infected with G. nipponicum and sera infected with Trichnella sp. or not infected. These results provide a rationale for evaluating esophageal proteins for the development of diagnostic methods for detecting G. nipponicum or Gnathostoma sp. infections.     

Production of monoclonal antibodies against avian LHRH-I

Summary Production of antibodies against peptides or poorly antigenic proteins by conventional methods often requires either large quantities of the native immunogen or some chemical modification to increase their antigenicity. In this study an in vivo and in vitro immunization protocol has been used to generate monoclonal antibodies against the decapeptide luteinizing hormone-releasing hormone (LHRH). Two injections of 100 μg of avian LHRH-I into BALB/c mice were given 7 d apart. Dissociated splenocytes were collected under sterile conditions. They were incubated with 100 μg of the immunogen in 75-cm² tissue culture flasks in thymocyte-conditioned media. After 5 to 8 d exposure to the antigen, splenocytes were fused with SP2/O myeloma cells by polyethylene glycol. The cells were plated into 24 wells and then incubated in hypoxanthine aminopterin and thymidine selective media. After 14 d an initial screening was done by enzyme immunoassay. The positive wells (6/24) were expanded into 96-well plates and rescreened. Selected lines were cloned out 3 times by limiting dilution and the most positive expanded for ascites production. The antibody was affinity purified in a protein A column. The antibody cross-reacted with LHRH-I and II but preferentially to LHRH-I, as shown by competitive assay. A hypothalamic extract from a mature chick showed a higher response than preparations from whole brain explants of 1- to 3-d posthatched chicks, mature quail, and mature mouse. This work was funded by the Maryland Agricultural Experiment Station artical no. A4975, contribution no. 8019.