2-D Western blotting for evaluation of antibodies developed for detection of host cell protein

Recombinant proteins generated for therapeutic use must be substantially free of residual host cell protein (HCP). The presence of host cell protein (HCP) is usually assayed by ELISA using a polyclonal antibody mixture raised against a population of proteins derived from the host cell background. This antibody should recognize as high a proportion as possible of the potential HCPs in a given sample. A recommended method for evaluating the assay involves two-dimensional electrophoretic separation followed by Western blotting.We present here a method using commercial anti-HCP antibody and samples derived from Chinese Hamster Ovary (CHO) cells. The 2-D electrophoresis procedure gives highly reproducible spot patterns and entire procedure can be completed in less than 2 days. Software analysis enables the straightforward generation of percent coverage values for the antibody when used to probe HCP-containing samples.