Purification of transgenic tobacco-derived recombinant human monoclonal antibody

Purification of recombinant monoclonal antibody from transgenic plant extract is technically challenging as it involves the processing of large volume of material, containing low titre of antibody, present along with large quantities of native proteins and other impurities. The conventional approach of capturing antibody from a clarified extract using packed-bed chromatography is therefore not particularly suitable. This study evaluates the suitability of using a combination of ultrafiltration and chromatography for purifying transgenic tobacco-derived human monoclonal antibody. A two-stage cascade ultrafiltration process removed about 97% impurities while ensuring almost complete recovery of antibody, providing 32-fold antibody enrichment in the process. The primary objective of the ultrafiltration step was to reduce the burden on the subsequent chromatographic steps. A two-step chromatographic process was then used to eliminate remaining impurities. Using this approach, recombinant human antibody expressed in tobacco could be purified to greater than 95% purity with 50% overall recovery (ca. 12.5mgantibody/kg tobacco tissues).