Serum-free production and purification of chimeric IgA antibodies

Natural IgA antibodies are abundantly produced in vivo to protect serosal surfaces from invading infectious organisms. However, the immunotherapeutic potential of IgA has hardly been explored, although there is evidence that recombinant IgA antibodies may broaden the armentarium to combat certain infectious or malignant diseases. One of the limitations for exploring IgA's therapeutic activity has been the difficulty to obtain enough recombinant material with desired specificity for in vivo studies. Here, we describe the production and purification of monomeric recombinant IgA1 and IgA2 antibodies under serum-free conditions. For antibody production, suspension adapted CHO-K1 cells and a glutamine synthetase selection vector were used, which resulted in specific production rates of up to 2.2 pg/cell/day. Purities of > 95% of monomeric antibodies were obtained by a combination of affinity chromatography–using an anti-κ-light chain matrix–and size exclusion chromatography. Purified antibodies displayed the expected biochemical characteristics and were functionally fully active. Importantly, all required reagents and methods are commercially available and not dependent on the specificity of the desired antibody. In addition, all employed technologies and methodologies are similar to those used for the production of therapeutic IgG antibodies — thus allowing further up-scaling and streamlining according to existing antibody production technologies. In conclusion, the described methodology may assist in the development of recombinant IgA antibodies for therapeutic applications.