Rational selection of an antibody probe to detect the heterogeneous collection of CHO-derived rhGM-CSF glycoforms.

Six anti-E. coli rhGM-CSF monoclonal antibodies were generated using hybridoma technology. One of these showed identical affinity for the CHO and E. coli-derived cytokine (dissociation constants of 0.14 +/- 0.01 nM and 0.13 +/- 0.01 nM, respectively), mapping an epitope that is not hindered by carbohydrates. The antibody was used to develop a simple, specific and sensitive competitive ELISA to quantify the entire set of rhGM-CSF glycoforms (detection limit of 780 pg/ml) and it was successful as an affinity ligand to purify them. Therefore, this particular antibody is a useful, reliable and reagent for most immunochemical purposes with the aim of detecting, quantifying and purifying the highly heterogeneous collection of the CHO-derived rhGM-CSF isoforms.