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

Developments in biotechnological research in Austria

Austria is a small European country with a small number of universities and biotechnological industries, but with great efforts in the implementation of environmental consciousness and corresponding legal standards. This review attempts to describe the biotechnological landscape of Austria, thereby focusing on the highlights in research by industry, universities, and research laboratories, as published during 1990 to early 1995. These will include microbial metabolite (organic acids, antibiotics) and biopolymer (polyhydroxibutyrate, S-layers) production; enzyme (cellulases, hemicellulases, ligninases) technology and biocatalysis; environmental biotechnology; plant breeding and plant protection; mammalian cell products; fermenter design; and bioprocess engineering.

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.

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.

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.