Purification of murine immunoglobulin E (IgE) by thiophilic interaction chromatography (TIC)

In addition to their known implication in allergy studies, IgE antibodies are becoming an increasingly interesting antibody class in cancer research. However, large-scale purification of IgE antibodies still poses substantial challenges, as they cannot be purified using techniques commonly used for other immunoglobulins such as protein A or protein G chromatography. Here, we have developed and optimised a gentle and simple IgE purification method based on thiophilic interaction chromatography (TIC). IgE binds to the thiophilic resin in presence of 1.2 M ammonium sulfate and is eluted in low salt concentration. Monomericity of purified antibodies ranged between 54 and 73%. Preparative size-exclusion chromatography was thereafter performed to further improve the purity, which reached >95% in the final product. The overall recovery was around 30%. The purification method was tested on both hybridoma-produced and recombinantly produced IgE antibodies with reproducible results. In addition, the antigen binding activity of purified IgE antibodies was preserved, as shown by binding ELISA. Purification by TIC is cheap, gentle in terms of pH to preserve IgE folding and function, and universal as any IgE antibody can be purified irrespective of the species of origin or affinity. Potentially, it could be used for purification of other antibody isotypes as well, when gentle conditions are required.