One-step procedure for the rapid isolation of mouse monoclonal antibodies and their antigen binding fragments by fast protein liquid chromatography on a mono Q anion-exchange column

Synthesis and screening of a rationally designed combinatorial library of affinity ligands mimicking protein L fromPeptostreptococcus magnus

Rational design and combinatorial chemistry were utilized to search for lead protein L (PpL) mimetics for application as affinity ligands for the purification of antibodies and small fragments, such as Fab and scFv, and as potential diagnostic or therapeutic agents. Inspection of the key structural features of the complex between PpL and human Fab prompted the de novo design and combinatorial synthesis of a 169-membered solid-phase ligand library, which was assessed for binding to human IgG and subsequent selectivity for the Fab fragment. Eight ligands were selected, chemically characterized and compared with a commercial PpL-adsorbent for binding pure immunoglobulin fractions. The most promising lead, ligand 8/7, when immobilized on an agarose support, behaved in a similar fashion to PpL in isolating Fab fragments from papain digests of human IgG to a final purity of 97%.

Gas6, a ligand for the receptor protein-tyrosine kinase Tyro-3, is widely expressed in the central nervous system

Gas6 (growth arrest specific gene-6) is a ligand for members of the Axl subfamily of receptor protein-tyrosine kinases. One of these receptors, Tyro-3, is widely expressed in the central nervous system. We have used biochemical and histological techniques, including in situ hybridization, to determine the expression patterns of Gas6 mRNA and protein during development. Gas6 is widely expressed in the rat central nervous system (CNS) beginning at late embryonic stages and its levels remain high in the adult. Gas6 is detected as a single 85 kDa protein, which is encoded by a single 2.5 kb mRNA species. At embryonic day 14 it is detected in the heart, blood vessels, testes, choroid plexus, and in the ventral spinal cord. In the adult, Gas6 is expressed in the cerebral cortex, (predominantly in layer V), the piriform cortex, and the hippocampus (areas CA1, CA3 and the dentate gyrus). It is also expressed in thalamic and hypothalamic structures, the midbrain, and in a subset of motor and trigeminal nuclei. In the cerebellum, it is expressed in Purkinje neurons and deep cerebellar nuclei. Protein S, a protein related to Gas6, is only detected at low levels in the CNS. The spatial and temporal profiles of Gas6 expression suggest that it could potentially serve as the physiologically relevant ligand for Tyro-3 in the postnatal rat nervous system.

Effect of salt concentration gradient on separation of different types of specific immunoglobulins by ion-exchange chromatography on DEAE cellulose

A three-stage process, consisting of an ammonium sulfate precipitation step, dialysis desalination with microporous anion-exchange Neosepta membranes and anion-exchange chromatography on DEAE-cellulose DE-52 was used for the isolation of mouse monoclonal antibodies specific against different antigens. The ascites fluids contained monoclonal antibodies against human IgG, against horseradish peroxidase and against the heavy chain of human IgM. The effect of the salt concentration gradient in the elution buffer was examined with the aim of optimizing chromatographic conditions. The quality of separation of protein zones was determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis under non-reducing conditions. The immunoreactivity of purified monoclonal antibodies was determined by enzyme-linked immunosorbent assay using a solid-phase adsorbed antigens against which each monoclonal antibody type was directed.

Characterization of beta2-glycoprotein I-dependent and -independent "antiphospholipid" antibodies from lupus-prone NZW/BXSB F1 hybrid male mice

Male (NZW x BXSB)F1 (W/BF1) mice develop a systemic lupus-like syndrome characterized by thrombocytopenia, coronary vascular disease, nephritis, and anticardiolipin antibodies. Three stable hybridoma cell lines secreting monoclonal anticardiolipin antibodies were developed from these mice by fusing their splenic lymphocytes with nonsecreting myeloma cell line, NS-1. Monoclonal antibody A1.17 reacted with cardiolipin in a beta2-Glycoprotein I-dependent manner. The epitope for this antibody consisted of beta2-glycoprotein I bound to cardiolipin or immobilized on plastic plates. Other anionic phospholipid-binding proteins, such as prothrombin or annexin V, had no significant effect in the reactivity of these antibodies. The specificity is similar to the autoimmune anticardiolipin antibodies described in patients with systemic lupus erythematosus and other infectious diseases. In contrast, monoclonal antibodies A1.72 and A1.84 reacted with cardiolipin in the absence of beta2-glycoprotein I. Beta2-glycoprotein I, either in the fluid phase or bound to cardiolipin, inhibited the binding of these antibodies. The specificity of the latter two antibodies was similar to that described in patients with syphilis and allied disorders. Both types of antibodies had lupus anticoagulant properties. Thus lupus-prone male (NZW x BXSB)F1 (W/BF1) mice develop both beta2-glycoprotein I-dependent and beta2-glycoprotein I-independent anticardiolipin antibodies.

PDGF mediates a neuron-astrocyte interaction in the developing retina

Astrocytes invade the developing retina from the optic nerve head, over the axons of retinal ganglion cells (RGCs). RGCs express the platelet-derived growth factor A-chain (PDGF-A) and retinal astrocytes the PDGF alpha-receptor (PDGFR alpha), suggesting that PDGF mediates a paracrine interaction between these cells. To test this, we inhibited PDGF signaling in the eye with a neutralizing anti-PDGFR alpha antibody or a soluble extracellular fragment of PDGFR alpha. These treatments inhibited development of the astrocyte network. We also generated transgenic mice that overexpress PDGF-A in RGCs. This resulted in hyperproliferation of astrocytes, which in turn induced excessive vasculogenesis. Thus, PDGF appears to be a link in the chain of cell-cell interactions responsible for matching numbers of neurons, astrocytes, and blood vessels during retinal development.

Purification of the monoclonal heparin antibody H-1.18

An antibody of the (immunoglobulin) IgG1 subclass against heparin was purified. Here we report on the purification of the heparin antibody. Ammonium sulfate precipitation was performed and showed a high purity of the precipitate. In the heparin radioimmunoassay it showed a high heparin binding. Capillary electrophoresis showed that albumin and other proteins were separated from the heparin antibody. The purification method allowed a large scale production of the heparin antibody.

Influence of column type and chromatographic conditions on the ion-exchange chromatography of immunoglobulins

Immunoglobulins are often purified by affinity chromatography. However, this technique is costly, can result in poor resolution for subclasses (or is only group specific), and leads to possible leaching of contaminants into the purified products. Ion-exchange chromatography has shown great potential and has found an increased usage in the purification of immunoglobulins. The aim of this study is to further understand the separation mechanism with emphasis on the influence of column type and chromatographic conditions on the peak shape, selectivity and changes in the elution patterns. Included are strong cation-exchange, strong anion-exchange and weak anion-exchange columns. Five immunoglobulin G antibodies were used as test probes. Some sera and ascites were also used in the study. Among the chromatographic conditions examined were mobile phase pH, buffer type, buffer concentration, gradient rate, and column temperature. Significant differences in the chromatographic behavior (elution pattern, peak shape and selectivity) of the test samples are discussed in regard to the column type and the chromatographic conditions.

Recombinant proteins L and LG: efficient tools for purification of murine immunoglobulin G fragments

In order to improve antibody purification methods, recombinant proteins L and LG were tested in the purification of murine monoclonal immunoglobulin G (IgG) and its fragments. After affinity constant evaluation in different buffer systems, high-performance affinity chromatographic columns were prepared by coupling the proteins to Affi-prep 10 resin and tested with eight different murine monoclonal antibodies and their fragments of different isotypes. Affinity chromatographic experiments confirmed radioimmunoassay results showing that protein L bound 75% of the tested antibody fragments whereas protein LG had affinity for all the tested fragments. These results demonstrate that protein LG is the most powerful Ig-binding tool so far described.

Protein S binds to and inhibits factor Xa

Although human protein S binds to human factor Va and inhibits prothrombinase activity, this inhibition is not totally dependent on factor Va. Hence, we investigated possible interaction of protein S with human factor Xa. Factor Xa, diisopropylphospho-factor Xa and their biotin derivatives ligand blotted specifically to protein S and protein S ligand blotted specifically to factor X and factor Xa. Biotinylated factors X and Xa bound to immobilized protein S and, reciprocally, protein S bound to immobilized factor Xa with a Kd of approximately 19 nM. In fluid phase, protein S bound to factor Xa with a Kd of approximately 18 nM. Protein S at 33 nM reversibly inhibited 50% of factor Xa amidolytic activity. Protein S inhibition of prothrombin conversion to thrombin by factor Xa was phospholipid-independent and was 1.6 times stimulated by Ca2+ ions. Inhibition of prothrombinase activity by protein S was 2.3-fold more potent in the presence of factor Va, with 50% inhibition at approximately 8 nM protein S. Protein S prolonged the factor Xa one-stage clotting time of protein S-depleted plasma in a dose-dependent manner. These data demonstrate mechanisms of anticoagulant action for protein S that are independent of activated protein C and that involve direct binding to factors Xa and Va and direct inhibition of factor Xa.

Common idiotypes expressed on human, monoclonal, abnormal immunoglobulins and cryoglobulins with polyreactive autoantibody activities

Several human monoclonal immunoglobulins with the same autoantibody activity have been shown to have cross-reactive idiotypes (CRI). In this study, using polyclonal anti-idiotypic antibodies, we found that 28% of human monoclonal immunoglobulins with polyreactive autoantibody activity from myeloma, Waldenström's macroglobulinaemia and cryoglobulinaemia patients shared common idiotype(s). Furthermore, the latter were expressed on human and murine natural MoAbs (respectively in 12% and 22% of the clones tested) and on human IgG preparations used for therapeutic intravenous injections (IVIg) and which contain natural antibodies. These findings suggest that monoclonal immunoglobulins could arise from the proliferation of a clone that normally produces a natural antibody. The existence of common idiotype(s) between monoclonal immunoglobulins and IVIg could be relevant to the improvement noted after treatment with IVIg in patients suffering from peripheral neuropathies associated with monoclonal gammopathy.

Purification of mouse antibodies and Fab fragments

Although monoclonal antibodies can have different properties, it should still be possible to purify any antibody to homogeneity. Often, by utilizing these differences, the purification procedure can be improved. All of the methods discussed are fairly simple and fast. With 1 week of work, over 50 mg of purified antibody can be realized. These methods can also yield material of sufficient quality for structural studies.

Application of phase partitioning and thiophilic adsorption chromatography to the purification of monoclonal antibodies from cell culture fluid

A two-step method for the isolation of an IgG1 monoclonal antibody against horseradish peroxidase from hybridoma cell culture supernatant is described. Purification was achieved using an aqueous two-phase extraction procedure in conjunction with thiophilic adsorption chromatography. In an aqueous two-phase system composed of 5% PEG 1540 and 22% phosphate the monoclonal antibody preferentially associates with the PEG-rich top phase whereas proteins such as albumin and transferrin partition into the salt-rich bottom phase. Final purification of the monoclonal antibody was achieved by subjecting the PEG-rich top phase to thiophilic adsorption chromatography. The monoclonal antibody purified to homogeneity retained its specificity for horseradish peroxidase as revealed by polyacrylamide gel electrophoresis and an enzyme-linked immunosorbent assay. The potential of this purification protocol for large scale applications is discussed.

Single-step purification of F(ab')2 fragments of mouse monoclonal antibodies (immunoglobulins G1) by hydrophobic interaction high performance liquid chromatography using TSKgel Phenyl-5PW

Hydrophobic interaction high performance liquid chromatography (HPLC) using TSKgel Phenyl-5PW was applicable to single-step purification of F(ab')2 fragments from pepsin digests of mouse monoclonal antibodies of IgG1 class. The digests were applied to the gel equilibrated with phosphate-buffered saline containing 1 M ammonium sulfate. F(ab')2 fragments were adsorbed onto the gel using the same buffer, and eluted by reducing the ammonium sulfate concentration to 0 M. The fraction containing F(ab')2 fragments was homogeneous (purity: higher than 98%) by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration HPLC. The recovery of the antigen binding site was 42-58%. The cycle time of the Phenyl-5PW HPLC was 45 min, and F(ab')2 of up to 2200 mg was purified in a cycle. This method could be useful especially for large scale purification of F(ab')2 fragments.

Development of immunoassays for human interleukin 3 and interleukin 4, some of which discriminate between different recombinant DNA-derived molecules

Two panels of hybridomas were produced that secreted monoclonal antibodies (MAbs) against recombinant DNA-derived human interleukin 3 and interleukin 4 (rhIL-3 and rhIL-4). From each panel, sensitive immunoradiometric assays (IRMAs) were developed which were capable of detecting the recombinant molecule used as the immunogen but were unable to recognize natural or other recombinant forms of the same cytokine. Subsequent studies using the MAbs from each panel showed that a number of the MAbs appeared only to recognize that particular recombinant molecule used as immunogen, with little or no binding to other recombinant forms of the molecule. By using MAbs that were found to be unrestricted in their recognition for different recombinant forms of the cytokines, it was possible to develop an IRMA for IL-4 that was capable of detecting natural IL-4 as well as all the recombinant forms equally. An IRMA was also developed for IL-3 but was not of equivalent sensitivity in detecting the different recombinant forms of IL-3 used in the study. The recombinant DNA-derived cytokine molecules used to raise the two panels of MAbs contained amino acid substitutions relative to the natural sequences, and these findings indicate that caution should be exercised when using immunoassays to estimate natural sequence molecules if antibodies raised to modified rDNA-derived molecules are used.

Preparation of clinical grade monoclonal antibodies from serum-containing cell culture supernatants

Three mouse monoclonal antibodies (Mab), RIV6, MN12, and WT31, were purified from cell culture supernatants containing foetal bovine serum (FBS) by two-step purification protocols, involving protein A affinity and ion exchange chromatography. Provided that the purification conditions were adapted to the physico-chemical properties of the individual Mab, clinical grade products could be obtained. The residual levels of bovine IgG originating from FBS were below 1% on a protein basis. Endotoxin levels were below 1 ng/ml. The contents of other serum proteins, DNA, and protein A were below or near the detection limits. The final products met the requirements for therapeutic Mab. Special attention was paid to the behaviour of foetal bovine IgG in the different purification steps. Large variations in the IgG contents of different batches of FBS were observed. However, the properties of the IgG fractions of the batches were very similar. A major IgG fraction with a low affinity for protein A and with components with relatively acidic isoelectric points (pIs) was distinguished from a minor fraction exhibiting a high affinity for protein A and a more diverse pI pattern. The impact of these findings on the purification strategy used for the Mab is discussed.

Production of polyclonal and monoclonal antibodies to human granulocyte colony-stimulating factor (GCSF) and development of immunoassays

Murine monoclonal antibodies and a sheep polyclonal antiserum against recombinant human granulocyte colony-stimulating factor (GCSF) have been produced. These have been used to develop an immunoassay which can detect 250 pg/ml (25 U) of both natural and recombinant human GCSF. The assay involves forming a complex between GCSF and a monoclonal anti-GCSF, binding of the complex to microtitre wells coated with sheep anti-GCSF and detection of the bound complex with 125I-labelled sheep anti-mouse IgG. Unlike the classical bone marrow assay and other cell line based bioassays for GCSF, the immunoassay was specific for the cytokine, showing no cross-reactivity with GM-CSF, IL-6, IL-3 or IL-1 alpha and -beta. The assay does not exhibit interfering matrix effects when used for the estimation of human GCSF in serum.

Immunochemistry of high molecular-weight human salivary mucin

The purpose of this study was to determine the distribution of mucin glycoprotein 1 (MG1) within submandibular, parotid, labial and palatine salivary tissues. Formalin-fixed and frozen tissue sections were examined histochemically with PAS, Alcian blue and Meyer's mucicarmine, and immunocytochemically with an anti-mucin glycoprotein 1 monoclonal antibody (clone 3/E8). Clone 3/E8 was produced in Balb/c mice using mucin-enriched chromatographic fractions from submandibular-sublingual saliva. The monospecificity of 3/E8 was confirmed by immuno-dot blotting and SDS-PAGE/electrophoretic transfer. Clone 3/E8 (IgG1; kappa) was of moderate affinity, and was directed to a carbohydrate-containing, TPCK-trypsin-insensitive and pronase-insensitive epitope on this mucin, which was not blood-group specific. The location of mucin glycoprotein 1 was determined by both indirect (peroxidase-antiperoxidase) and direct methods. Mucin glycoprotein 1 was localized within all labial acini examined, but was not found within parotid tissues. Histochemical methods stained all submandibular, palatine and labial acini, but immunocytochemistry with monoclonal antibody revealed heterogeneous staining with clone 3/E8 in submandibular and palatine tissues. These findings suggest the presence of mucin glycoprotein 1-specific acinar cell subpopulations within human submandibular and palatine salivary tissues.

Applications of preparative high-performance liquid chromatography to the separation and purification of peptides and proteins

The basic differences between the problems encountered in the development of the analytical and preparative applications of high-performance liquid chromatography are analyzed and the principles of optimization of a preparative separation outlined. The application of these principles to the purification of peptides and proteins are discussed with emphasis on the specific problems raised by the separation of high-molecular-mass compounds. The relative advantages and inconveniences of displacement and overloaded elution are presented. The applications of the various retention modes of liquid chromatography (ion exchange, reversed-phase adsorption, hydrophobic interactions, size exclusion and bioaffinity) to the separation of various peptide and protein mixtures and/or to the extraction and purification of some of these compounds are reviewed. Separation performance reported in the literature are summarized in table form.

Comparison of protein A, protein G and copolymerized hydroxyapatite for the purification of human monoclonal antibodies

Protein A Superose, protein G Sepharose fast flow and copolymerized hydroxyapatite were used for the purification of human monoclonal antibodies against HIV 1. Both desalted culture supernatant and a prepurified protein solution were used as starting materials. The different runs were compared with respect to yield and recovery of biological activity. The biological activity (specific reactivity) was checked by antigen enzyme-linked immunosorbent assay with recombinant antigen. The human monoclonal antibodies could not be selectively eluted from the hydroxyapatite but elution could be effected from the protein A Superose at pH 4.0 and from protein G at pH 3.0. The eluted immunoglobulin G was distributed over a broad pH range when protein G Superose was used. Biologically active material could be obtained from protein A Superose and protein G Sepharose fast flow.

The production and characterisation of monoclonal antibodies against human prolactin and the development of a two-site immunoradiometric assay

Monoclonal antibodies against human prolactin (PRL) have been produced and characterised and used to develop a sensitive two-site immunoradiometric assay (IRMA). Nine anti-PRL monoclonal antibodies were assessed for reactivity in immunoblotting experiments with PRL, hPL, hGH and pituitary gland extract. There was no detectable crossreactivity with hPL or hGH. In liquid phase radioimmunoassay (RIA) studies using three of the antibodies there was no detectable crossreaction from hPL or hGH. Five antibodies were positive in immunocytochemical studies using sections of human pituitary gland. Using FPLC purified monoclonal antibodies, a two-site IRMA was developed that could assay PRL over the range 17.5-3500 mIU per litre and was readily adapted to assaying serum samples from patients. The two-site IRMA could be performed within one day without loss of sensitivity and has potential as a rapid and simple method for screening clinical samples.

Purification of monoclonal antibodies raised against prostate-specific acid phosphatase for use in vivo in radioimaging of prostatic cancer

In developing diagnostic reagents for the radioimaging of prostatic cancer, methods were optimized for the purification of two mouse IgG1 monoclonal antibodies raised against prostate-specific acid phosphatase and produced in cell culture. Two different two-step methods were selected. One method consisted of two successive ion exchange chromatographic steps on Mono S and Mono Q; in the other method, Mono S chromatography was followed by hydrophobic interaction (Alkyl Superose) chromatography. In both cases, fast protein liquid chromatography (FPLC) instrumentation was used. The antibodies were purified from cell culture media containing fetal calf serum (1-5%). Highly pure (greater than 95%) IgG1 antibodies, free of contaminating serum-derived proteins or column materials, were obtained in good yield (greater than 90% recovery). The purified antibodies completely retained their immunological reactivity towards prostate-specific acid phosphatase and were sterile and pyrogen-free. Since the monoclonal antibodies produced were intended for applications in vivo, an essential feature of the methods selected was the availability of in situ cleaning procedures for sterilization of the gel materials and for the inactivation of viruses and pyrogens in the gels. The methods developed could be readily scaled up for preparative purposes.

A comparison of four cathepsins (B, L, N and S) with collagenolytic activity from rabbit spleen

We have separated four cathepsins (B, L, N and S) from rabbit spleen. They are all collagen-degrading cysteine proteinases, with Mr values of 25,250, 23,500, 34,000 and 30,000 for cathepsin B, L, N and S respectively. Cathepsins B, N and S have isoelectric points of 5.4, 6.2 and 6.8 respectively, whereas cathepsin L exhibited multiple charge forms in the range 5.0-5.7. A comparison of their specific activity against a variety of protein and synthetic substrates shows many differences. These differences can be visually illustrated through isoelectric focusing and detection of enzymic activity with protein and synthetic-substrate overlays. By using an enzyme-linked immunosorbent assay based on the binding to chicken cystatin and detection with polyclonal and monoclonal antibodies to native cathepsins B and L, no cross-reactivity of the four native enzymes was observed. Studies on the co-operative or synergistic effect in degrading collagen indicated that, of the different combinations tested, only the combination of cathepsin B and N exhibited enhanced collagenolysis.

One-step purification of monoclonal IgG antibodies from mouse ascites. An evaluation of different adsorption techniques using high performance liquid chromatography

Monoclonal antibodies were purified in one step from mouse ascites by four different high performance liquid chromatography (HPLC) adsorption techniques. The antibodies were of the IgG1, IgG2a, IgG2b and IgG3 subtypes, with isoelectric points between 6.4 and 7.6. Similarly pretreated samples were applied to columns for anion exchange (Mono Q), cation exchange (Mono S), chromatofocusing (Mono P) and hydrophobic interaction chromatography (Alkyl Superose), respectively. Highly purified IgG fractions, as judged by electrophoresis, were obtained in all these techniques. The yields of immunoreactive material were above 80%. A strategy for single step HPLC purification of monoclonal IgG antibodies from mouse ascites by adsorption techniques is proposed, as a complement to the well-established technique of affinity chromatography on immobilized protein A. The strategy involves (i) cation exchange chromatography as a first choice for antibodies with high isoelectric points (greater than 7.2), and (ii) hydrophobic interaction chromatography as a first choice when the isoelectric point is below 7.2.

Transmission densitometry of stained nitrocellulose paper

We report a simple solution to the problem of quantitative densitometry of stained nitrocellulose paper. By immersing the paper in a household lubricating oil of matching refractive index, the light-scattering properties of the paper are largely eliminated, allowing precise transmission densitometry in any flat bed densitometer. The method was evaluated on immunochemically stained Western blots of the proteinases cathepsins B and L. An approximately linear relationship was found between the integrated absorbance of the stained zone and the logarithm of the amount of protease applied to the polyacrylamide gel over the range of 150 to 350 ng of cathepsin B and 50 to 250 ng of cathepsin L.

Inhibition of in vitro fertilization by a monoclonal antibody reacting with the zona pellucida of the oviductal egg but not with that of the ovarian egg of the golden hamster

A glycoprotein designated ZP-0 is secreted from the epithelial cells of the oviduct and is bound to the zonae pellucidae (ZPe) of the oviductal eggs. We have previously established a monoclonal antibody reacting with ZP-0, termed AZPO-8. In the present study, we have examined the effect of AZPO-8 on in vitro fertilization in the hamster. Treatment of the oviductal eggs with AZPO-8 at concentrations of more than 100 micrograms/ml resulted in: (1) the formation of "zona precipitation" on the outer region of the ZP; (2) inhibition of sperm binding to ZP; (3) the acquisition of resistance to protease treatment. Fertilization was inhibited by AZPO-8 in a dose-dependent manner. These results indicate that a monoclonal antibody (MoAb) to an additional component of ZP derived from the oviduct shows an inhibitory effect on fertilization in vitro.

Purification of ascitic fluid-derived murine monoclonal antibodies by anion-exchange and size-exclusion high-performance liquid chromatography

Ascitic fluid-derived murine monoclonal antibodies (MoAbs) of immunoglobulin (Ig) M and IgG isotypes (IgG1 and IgG2a subisotypes) were previously prepared against an isolate of Actinobacillus sp (CAs8C) for the purpose of identifying and characterizing outer membrane antigens on this bacterium. An attempt was made to purify these MoAbs by anion-exchange and size exclusion high-performance liquid chromatography (HPLC). Hybridomas producing the IgG1 and IgG2a MoAbs posed unique difficulties in that they also secreted irrelevant IgG2b MoAbs that were present in the ascitic fluids. Anion-exchange chromatography (Protein-Pak DEAE-5PW column), with a simultaneous change in gradients of pH and ionic strength, was used to purify IgG and as a first step in the purification of IgM. There was good separation of IgG2b from IgG2a, but not from IgG1. Size-exclusion chromatography (Protein-Pak 300 SW column) was required to complete the purification of IgM. The presence of MoAbs in the HPLC fractions was confirmed by discontinuous gradient polyacrylamide gel electrophoresis (denatured and either reduced or non-reduced conditions) and the enzyme-linked immunosorbent assay. HPLC-purified MoAbs were free from transferrin and albumin and retained their specificity for As8C.

Development of a general ligand for immunoaffinity partitioning in two phase aqueous polymer systems

The effect on the partition of erythrocytes in a two phase aqueous polymer system based on dextran T500 and polyethylene glycol (PEG) 8000 of a combination of immunoaffinity ligands, namely, rabbit immunoglobulin G (IgG) and PEG 1900-modified monoclonal IgG, was examined as a potential cell separation technique. Several hybridoma lines secreting mouse monoclonal IgG specific for the Fc receptor of rabbit IgG were raised. The monoclonal IgG was modified by cyanuric chloride attachment of PEG 1900, causing the modified antibody to partition predominantly into the PEG-rich upper phase of the systems. The PEG-modified monoclonal IgG was used as an affinity ligand in the two phase polymer system to specifically increase the partition of rabbit anti-NN glycophorin IgG. The rabbit IgG was applied together with the PEG-modified monoclonal IgG to increase the partition of human erythrocytes. The same system had no effect on the partition of rabbit erythrocytes. These experiments demonstrate that a monoclonal antibody can be modified and used as a general reagent with which to alter cell partition in two phase aqueous polymer systems in an immunologically specific manner.

Characterisation of two differently processed forms of human recombinant factor IX synthesised in CHO cells transformed with a polycistronic vector

A stable transformed cell line constitutively expressing human factor IX has been established. Wild-type Chinese hamster ovary cells (CHO cells) were transformed using a polycistronic expression vector carrying a previously isolated factor IX cDNA and a selection gene encoding the Escherichia coli xanthine-guanine phosphoribosyl transferase. One clone, CHO 622.4, contains a high number of genomically integrated plasmids and secretes 1-3 mg factor IX l-1 day-1 into the culture medium with a biological activity ranging from 25% to 40%. The recombinant molecule was purified either by conventional chromatography or by immunoaffinity chromatography using antibodies specific to a calcium-induced factor IX conformer. The purified recombinant protein migrates as a single band with the same mobility as that of natural factor IX on SDS/polyacrylamide gels. N-terminal sequencing shows tow differently processed forms of recombinant factor IX: whereas the majority of the zymogen is correctly processed, approximately 20% of the purified recombinant molecule contains an 18-amino-acid NH2-extension corresponding to the precursor form of factor IX. Analysis of the 4-carboxyglutamic acid content indicates a high but incomplete carboxylation (70%) of the recombinant molecule as compared to natural factor IX. The carbohydrate composition of both the natural and recombinant molecules has been determined. Both molecules have a N-glycan structure of similar complexity, indicating that factor IX contains all the information to direct the same glycosylation pattern in human liver cells and in an unrelated cell line such as CHO-K1.

Screening of monoclonal antibodies using antigens labeled with acetylcholinesterase: application to the peripheral proteins of photosystem 1

An original immunoenzymatic screening method, based on the use of antigens labeled with the stable enzyme acetylcholinesterase (AChE, EC 3.1.1.7), is described. The high turnover of this enzyme results in a very sensitive detection of antibodies. In this method, monoclonal antibodies from the supernatants of hybridoma cultures are immobilized on a solid phase coated with anti-mouse immunoglobulins and react simultaneously with the appropriate antigen labeled with biotin molecules. In a second step, biotinylated acetylcholinesterase is in turn associated to the system via avidin interactions and subsequently detected by a colorimetric assay. The method appears more sensitive and easier to use than either the corresponding radioimmunological test using a 125I-iodinated antigen or the same type of enzymatic immunoassay performed with biotinylated horseradish peroxidase instead of biotinylated AChE. The combined use of microtiter plates, solid-phase separation, and colorimetric detection allows a high level of automation of the method which makes it very efficient to process a large number of samples. This technique has been successfully applied to the screening of monoclonal antibodies directed against peripheral proteins of the photosystem 1 (PS1) membrane complex in photosynthesis. A complete set of antibodies recognizing these PS1 components was selected. The same technique was also tested in competition immunoassays and appears to be a very precise and useful tool for quantifying PS1 polypeptides in different biological extracts, including sodium dodecyl sulfate-denatured membranes. This can be of special interest for studying the biogenesis of membrane complexes.

A mouse monoclonal antibody that binds to an alpha-stichocyte of Trichinella spiralis

Monoclonal antibodies were generated for the isolation of specific antigens from Trichinella spiralis. A monoclonal antibody (TS32D12) of the IgG1 class was selected according to its reactivity and specificity by enzyme-linked immunosorbent assay and immunofluorescent technique. The TS32D12 antibody was purified from ascites by fast protein liquid chromatography. The purified antibody showed a sensitive reaction to the T. spiralis antigen, but not to any other heterologous parasite antigens so far examined. Western blot analysis showed that the monoclonal antibody bound to epitopes present on the 160-kDa molecule. The antigen molecule was fragmented into 56-kDa molecules by heat treatment. The epitopes seemed to be destroyed since the antibody could not bind to the 56-kDa molecule. Staining with the periodic acid-Schiff (PAS) reagent suggested that the two molecules of 160 kDa and 56 kDa were glycoproteins. The 160-kDa molecule was detected only in the alpha-stichocyte of T. spiralis muscle larvae.

Selective non-adsorption preparative chromatography of bovine immunoglobulin Gl

Bovine immunoglobulin Gl (IgGl) was purified from blood serum by isocratic elution through a mixed-bed ion-exchange column at low ionic strength. Selection of a mobile phase pH near the isoelectric point of IgG precluded its binding to the strong cation- and anion-exchange sorbents and allowed IgGl to be eluted isocratically. Under these conditions most of the other components in the serum sample were retained on the mixed-bed column. This approach gives excellent throughput and purity.

Human hematoxylin-stainable protein of keratohyalin granules origin. I. Extraction and purification

A human hematoxylin-stainable protein (HSP) was extracted from the massive stratum corneum of epidermal cysts. This protein was purified in two steps; first, through preparative isoelectric focusing, and, second, by affinity column chromatography bound with the specific, monoclonal antibody to keratohyalin granules (Ted-H-1). In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified HSP consisted of two proteins (70 and 62 kilodaltons [kd]), but only the 62-kd protein was detected in the 15,000 g supernatant fraction of the extract using the immunoblotting technique. The amino acid composition of the purified HSP included 30% glycine, 15% serine, 12% glutamic acid, and 4% ornithine, but only 2.3% histidine. Using the indirect immunofluorescent technique, observation showed that the monoclonal antibody, Ted-H-1, to the HSP, formed as a result of the partially purified antigen, was located in three places: 1) the keratohyalin granules; 2) in the cell membrane region of the lower part of the stratum corneum of the skin samples (forearm, cheek, and back); and 3) the keratohyalin granules in the follicular epithelium and on the trichohyalin granules. Reaction product was not seen in either the acrosyringium or in the plantar epidermis. As two positively reacted proteins with the Ted-H-1 were detected in the Tris-HCl extract from the plantar stratum corneum by the immunoblotting assay, however, the above negative result in the indirect immunofluorescent studies may be due to the masking of the antigenic site of keratohyalin granules in vivo. This hematoxylin-stainable protein was synthesized as one component of the keratohyalin granules in the stratum granulosum and may have been transferred to the stratum corneum cell membrane region.

Chromatography of complex protein mixtures

This review has shown that a variety of chromatographic techniques are available for fractionating proteins. Fortunately, high-quality columns of every type described in this review are commercially available. Most water-soluble proteins may be eluted from size-exclusion, hydrophobic-interaction, ion-exchange, metal chelate, and bioaffinity columns with ease. When this is the case, high recovery and retention of biological activity are the norm. The exception is reversed-phase chromatography where the organic solvents and acids used in polypeptide elution denature many proteins. When problems do occur, they are generally the result of unique structural features of the protein. Very hydrophobic proteins have presented the biggest problem in that they are difficult to solubilize, particularly with retention of biological activity. It has been found that zwitterionic and non-ionic detergents are the most suitable solubilizing agents, but urea has also been used in cases where hydrophobic interacts are not as strong. Unfortunately, there is still an element of trial-and-error in selecting the most suitable solubilizing agent. Heterogeneous glycosylation of proteins also presents a problem. Both neutral and charged monosaccharides can be incorporated into proteins through multiple steps at several sites. Thus, there is the potential in a sample for a large number of glycoprotein species which have the same polypeptide backbone and differing amounts of oligosaccharide. A problem arises when size-exclusion, ion-exchange, hydrophobic-interaction, reversed-phase and bioaffinity systems begin to discriminate between these very similar glycoprotein species. Chromatographic peaks can become very broad, due to incomplete fractionation, and the polypeptide chain of interest can be associated with multiple peaks. The separation of glycoproteins requires much more study before logical procedures can be suggested for column selection and operation. Aggregated species are another class of proteins which present occasional problems. Multimeric proteins are adsorbed to sorbents by a series of forces, among which are hydrogen bonding, hydrophobic interactions, and electrostatic forces. These forces are also responsible for the maintenance of quaternary structure in proteins. When the same forces dominate both retention of protein structure and adsorption at the sorbent surface, the quaternary structure of the protein can be disrupted during elution. Very basic proteins also present a problem in some cases. Columns with residual negative charges, such as a silica-based reversed-phase column, adsorb anionic species so strongly that they are difficult to elute.(ABSTRACT TRUNCATED AT 400 WORDS)

Combination of Zetaprep mass ion-exchange media and high-performance cation-exchange chromatography for the purification of high-purity monoclonal antibodies

A procedure involving diafiltration, mass ion exchange on a QAE Zetaprep disk, gel chromatography and cation-exchange chromatography was used for the purification of mouse monoclonal antibodies from hybridoma culture supernatant. Prior to the separation steps, the starting solution was adjusted to the desired pH and conductivity. Diafiltration was used for this purpose in order to keep the volume constant or even to reduce the volume of sample. A QAE Zetaprep disk was used to remove the main protein contaminants from the culture supernatant. After washing unbound proteins out of the Zetaprep disk, slightly bound protein was eluted with a buffer solution containing 50 mM sodium chloride. The monoclonal antibody was eluted with a solution containing 150 mM sodium chloride. The purity of the eluted antibody was 50%, and was increased to 99% by subsequent high-performance cat-ion-exchange chromatography. The purity was determined by means of sodium-dodecyl sulphate polyacrylamide gel electrophoresis and silver staining. The advantage of the two high-performance techniques, mass ion exchange and high-performance cation-exchange chromatography, are the high-flow-rates and the high resolution that can be obtained. These techniques are suitable for the production of injectable therapeutic preparations.

An improved immunoblotting procedure for the detection of antibodies against HIV

Immunoblotting ('Western blotting') is routinely used for detection of antibodies against HIV in the diagnosis of HIV infection. We describe an improved procedure, which does not require virus purification and is easy to control for 'false-positive' results. The technique also does not produce erroneous results due to reactivity of the developing system with residual cellular proteins or viral antigens and does not give high nonspecific background staining. The technique can be applied to the detection of antibodies to HIV in serum, plasma, and blood products.

Simple and rapid purification of monoclonal antibodies from cell culture supernatants and ascites fluids by hydroxylapatite chromatography on analytical and preparative scales

A simple and rapid method for the purification of murine and human monoclonal antibodies from ascites fluids and cell culture supernatants is described. The method, based on the use of hydroxylapatite (HAP) column chromatography, is applicable on both analytical and preparative scales. In our work on purification of monoclonal antibodies, we have found that the combination of a single step elution of impurities followed by linear gradient elution of antibody provides an excellent purification of the antibody from cell culture and ascites fluids. The procedure provides very good resolution at high flow rates. The cell culture supernatant can be pumped on the preparative column at the rate of 2-3 ml/min without any measureable back pressure. The binding is independent of the flow rate. This method has been successfully used to purify several monoclonal antibodies of different subtypes from cell culture supernatants.