Purification of a murine monoclonal antibody of the IgM class

Isolation and Characterization of IgM and IgY Antibodies from Plasma of Magellanic Penguins (Spheniscus magellanicus)

Infectious diseases such as aspergillosis, avian malaria, and viral infections are significant threats to the conservation of penguins, leading to morbidity and mortality of these birds both in captivity and in the wild. The immune response to such infectious diseases is dependent on different mechanisms mediated by cells and soluble components such as antibodies. Antibodies or immunoglobulins are glycoproteins that have many structural and functional features that mediate distinct effector immune functions. Three distinct classes of antibodies have been identified in birds: immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin Y (IgY). In this study we aim to establish an efficient laboratory method to obtain IgM and IgY antibodies from plasma samples of healthy adult Magellanic penguins (Spheniscus magellanicus). The protocol was developed combining plasma delipidation, sequential precipitation with caprylic acid and ammonium sulfate, and size-exclusion chromatography. The efficiency of the protocol and the identity of the purified IgM and IgY antibodies were confirmed through enzyme-linked immunosorbent assay, Western blotting, one-dimensional and two-dimensional polyacrylamide gel electrophoresis, and lectin binding assay. Structural and physicochemical properties of IgM and IgY from Magellanic penguins were consistent with those of other avian species. This purification protocol will allow for more detailed studies on the humoral immunity of penguins and for the development of high specificity serologic assays to test Magellanic penguins for infectious pathogens.

Monoclonal antibodies against hepatitis B viral surface antigens and epitope grouping

Monoclonal antibodies (MAbs) were generated against subtypes (ad/ad/rw) of the human hepatitis B viral surface antigen (HBsAg). Among dozens of antibodies that were generated, the majority was shown to commonly react with various ad/ay subtypes of the S protein. Epitope(s) of these antibodies were grouped by various immunoassay methods, and at least four distinct epitope regions were identified. Some of these antibodies were selected to formulate sandwich enzyme immunoassays for quantitative determinations of HBsAg in reconstituted specimens. Epitope-defined monoclonal antibodies with high affinity and specificity might be suitable for formulations as vaccines (containing a mixture of humanized monoclonal antibodies) for passive immunization in humans for immunoprophylaxis of HBV infection.

Development of a two-step chromatography procedure that allows the purification of a high-purity anti-histone H1 monoclonal immunoglobulin M antibody with immunosuppressant activity

In organ transplantation, the development of a novel immunosuppressant free of the need for permanent administration and any serious side effects has eagerly been awaited. We have previously reported that an anti-histone H1 polyclonal antibody has immunosuppressant activity. Here we prepared an anti-histone H1 monoclonal antibody as an analytical tool to elucidate its mechanism of immunosuppression. The isotype of this monoclonal antibody was immunoglobulin M. A monoclonal antibody prepared for administration to organ transplantation model animals should not contain any allogenic proteins and should have high purity. Therefore, we conducted a two-step chromatography procedure, consisting of strong anion-exchange chromatography and gel filtration chromatography, to purify an anti-histone H1 monoclonal immunoglobulin M antibody from the serum-free culture supernatant of hybridomas. Consequently, we successfully purified the monoclonal antibody at 96%, a purification rate at which its administration to organ transplantation model animals is possible.

A comparison of type I collagen, fibronectin, and vitronectin in supporting adhesion of mechanically strained osteoblasts

We used an adhesion assay for cells cultured under high dynamic strain to measure human osteoblast-like HOS cell adherence to immobilized type I collagen, fibronectin, and vitronectin. These conditions were designed to model the increased forces present at unstable fractures or loose joint prostheses. At a constant, low protein-coating density (1000 molecules/microm2) and 20% cyclic strain for 24 h, type I collagen, fibronectin, and vitronectin supported 24.6 +/- 2%, 16.7 +/- 3%, and 1.1 +/- 1% adherence, respectively, which paralleled the relative number of integrin-binding sites in each protein. Thus, when the number of available binding sites was limited, strain resistance was proportional to the number of integrin-ligand interactions. In contrast, at high protein-coating densities (> or = 2,500 molecules/microm2), vitronectin supported greater adherence (45.7 +/- 2%) when compared with type I collagen (37 +/- 2%) or fibronectin (34.8 +/- 2%) and directed constitutive expression of osteopontin (OPN), which suggested that there exist discrete signals on vitronectin receptor occupancy that promoted cell adherence and survival under strain. Integrin-mediated binding was necessary for resistance to strain, as evidenced by the low levels of strain resistance observed when cells were adherent in a nonintegrin-dependent manner. These findings support the utilization of at least two distinct mechanisms (i.e., tensegrity and integrin-mediated signal transduction) by HOS cells to remain adherent and viable on exposure to mechanical forces.

Purification of monoclonal antibodies from ascitic fluid using preparative electrophoresis

Four monoclonal antibodies (including Ig subclasses, G1, G2a, and G2b) were purified from murine ascitic fluid by a preparative electrophoresis system using a charge- and size-based strategy. Most of the smaller contaminating proteins were removed at pH 8.3 when the ascitic fluid was passed through a cartridge containing a separating membrane with a pore size of M(r) 100,000. After this single step, the immunoglobulin heavy and light chains were the only significant bands present when analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A second step, involving electrophoresis at pH 6.4-7.5 depending on the antibody can be used to remove residual contaminants. For each of the antibodies tested, the recovery of activity at each step was over 80%. As this technology is directly scalable, purification of antibodies by the method described here could be considered a cost effective alternative to protein A chromatography.

Efficient purification of mouse anti-FGF receptor IgM monoclonal antibody by magnetic beads

Affinity chromatography has been widely used for the purification of monoclonal antibodies (MAb). Traditionally, activated agarose beads conjugated with specific antisera have been used as a solid support in chromatographic protein purification. Magnetic beads conjugated with various antibodies have recently become an alternative method for the isolation of diverse proteins, nucleic acids, and cell types. In this study, murine anti-fibroblast growth factor receptor 1 (FGFR1) immunoglobulin M (IgM) was isolated from protein solutions to compare immunoaffinity column chromatography and magnetic bead IgM purification methods. Using immobilized rat anti-mouse IgM MAb, an UltraLink 1-ethyl-3-(3-dimethylaminopropyl)carboiimide (EDC)/diaminodipropylamine (DADPA) immunoaffinity column and polystyrene-coated magnetic beads were used for the purification of mouse IgM from bovine serum albumin/phosphate-buffered saline (BSA/PBS) as well as from crude ascites. Protein quantitation and percent IgM yield were determined by reducing SDS-PAGE electrophoresis followed by silver staining, then IgM and protein contaminants were quantitated using densitometry analysis. IgM anti-FGFR1 binding specificity and immunologic activity were determined by enzyme-linked immunosorbant assay (ELISA). This study demonstrates that magnetic bead isolation of IgM from ascites is more effective than traditional affinity chromatography purification as determined by greater IgM yield, purity, and immunologic activity.

Pilot scale purification of human monoclonal IgM (COU-1) for clinical trials

No standard procedure is available for the purification of human monoclonal antibodies for human i.v. administration. Here we describe the procedure developed for pilot scale purification of the human IgM monoclonal antibody COU-1 directed against a cancer-associated antigen. The hybridoma cells were grown in protein-free medium and purification from the clarified culture supernatant was carried out in 4 simple chromatographic steps: (1) hydroxylapatite chromatography; (2) hydrophobic interaction chromatography on phenyl-Sepharose: (3) cation-exchange chromatography on sulphonyl-Sepharose; and (4) anion-exchange chromatography on tetraethylamino-Sepharose. The product was substantially pure with regard to protein after step 3, but contained DNA which was removed in step 4. The average recovery of the IgM was 54% with a range of 40-65%. Importantly, the ability of the antibody to bind to its antigen in ELISA was fully maintained during the purification. Subsequently, the purified antibody was isotope labelled and successfully used for in vivo detection of colon, rectal and pancreas carcinomas in patients. The purification procedure described appears to compare favourably with previously published methods, but a critical comparison is not possible due to the lack of necessary information in the available literature.

Preparation of a monoclonal antibody to a glycidic epitope of the epidermal growth factor receptor that recognizes inhibitors of astrocyte proliferation and reactive microglia

A mouse monoclonal antibody (5B9), directed against a carbohydrate epitope of human epidermal growth factor receptor (EGFR), recognized an 81-kDalton glycoprotein in buffer-soluble and detergent-solubilized rat brain extracts (BE). The glycoprotein was more abundant in extracts prepared from injured brain than in those from normal tissue. Removal from BE of the antigens recognized by 5B9 increased their astrocyte mitogenic activity. Sections of injured rat brain and cultures derived from damaged brain, enriched in microglia, showed 5B9 immunoreactivity in ED1-positive cells. The abundance of the glycoprotein recognized by 5B9 in injured, relative to normal, tissue, suggested that molecules with EGFR immunoreactivity may be expressed in reactive microglial cells and released after injury.

Purification of murine immunoglobulin M from spent tissue culture supernatant by one-step gel filtration chromatography procedure

Optimal purification of immunoglobulin M (IgM) grown as spent tissue culture supernatant can be achieved by a straightforward size-exclusion chromatography procedure. Preparative isolation of IgM was achieved by precipitation with saturated ammonium sulphate to achieve a 45% solution. IgM was then purified by gel filtration chromatography with a solution of 100 mM Tris + 150 mM NaCl at pH 8. Denaturing electrophoresis and Western immunoblotting revealed two prominent bands at 80 and 25 kDa, indicative of the heavy and light chains of IgM respectively. The specific immunoreactivity of this IgM was assessed by a modified enzyme antigen capture assay. In contrast to affinity and ion-exchange chromatographies, gel filtration allows retention of IgM immunoreactivity.

Purification and immunochemical characterization of a natural human polyreactive monoclonal IgM antibody

In vitro and in vivo experiments to explain the function of natural polyreactive antibodies, usually of the IgM isotype, require large amounts of purified antibodies. We have developed a two-step purification procedure using a human natural polyreactive monoclonal IgM antibody (CB03). This combines hydrophobic interaction chromatography on phenyl-Superose and gel filtration over Superose 12 and readily permits scaling-up to isolate mg to g amounts of antibody. Retention of the CB03 antibody during gel filtration by precipitation and interaction with the gel matrix was overcome by the addition of 10 mM 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate. The yield of purified antibody was 34% and Fab fragments were obtained from the purified CB03 antibody by hot tryptic digestion (yield, 68% of theoretical amount). In an enzyme-linked immunosorbent assay, Fab and complete antibody had similar reaction patterns with different antigens.

Purification of two murine monoclonal antibodies of the IgM class by hydroxylapatite chromatography and gel filtration

A two-step method using hydroxylapatite chromatography and gel filtration is described for the purification of two murine monoclonal antibodies of the IgM class. Ascites fluid from each hybridoma was diluted in sodium phosphate buffer (0.01 M, pH 6.8), loaded onto a hydroxylapatite column and eluted with a stepwise sodium phosphate gradient. The immunoreactive protein peaks were concentrated and subjected to gel filtration using either Sephadex G-200 or Sephacryl S-200HR. The biological activity of the end-products was confirmed by complement lysis assay and by indirect immunofluorescence and flow cytometry. The purity of the end-products as assessed by SDS polyacrylamide gel electrophoresis and densitometry was at least 90%. The methods described produced immunoreactive material with a high level of purity. The procedure for each antibody was reproducible and provides a reliable method for purification of monoclonal antibodies of the IgM class.