Purification and stabilisation of a poorly soluble mouse IgG3 monoclonal antibody

The anti-T cell monoclonal antibody (Mab) RIV9 (mouse IgG3, kappa) has been developed for clinical use in the treatment of allograft rejection. In order to obtain a clinical grade Mab preparation, RIV9 was purified from cell culture supernatants by protein A affinity and anion exchange chromatography. Reasonable yields of highly purified product could only be obtained if stabilising compounds were added and Tween 80 was used in all stages of the purification process. Prior to anion exchange chromatography, dextran sulphate (MW 5000) was added to keep the Mab in solution. Many other additives were tested but did not solubilise RIV9 under the low salt strength conditions required for ion exchange chromatography. The complex character of the solubility-determining factors was demonstrated by the influence of buffer composition, buffer concentration, pH, and sodium chloride concentration on the solubility of RIV9.