The Amersham HCPQuant CHO cell lysate kit is designed to quantify Chinese hamster ovary (CHO) host cell protein (HCP) contamination in process-derived samples. This HCP assay has been developed by Rockland Immunochemicals, Inc. in collaboration with Cytiva, and extensively validated. The combination of high coverage (89%) with a broad linear range (2–200 ng/mL) increases the confidence of HCP quantification in both the low and high molecular weight ranges, which is critical to managing the risk of the immunogenicity effect arising from HCP in process-derived samples. These antibodies react strongly with CHO-K1 cell lysates, showing extremely high sensitivity for cells harvested at 60–85% viability. They were generated against CHO-K1 cell lysates that were derived from cells grown in chemically-defined media.