Host-cell proteins (HCPs) are bioprocess-related impurities that may be present in intermediate or final biopharmaceutical products such as recombinant monoclonal antibodies (MAbs). Although the potential clinical and genetic effects of HCPs are largely unknown, studies have shown that HCPs may cause immune responses and adverse reactions in patients when present at sufficient high levels (1,2,3). Consequently, US Food and Drug Administration (FDA) and European Commission regulations require that the level of HCP in a bioproduct be quantitatively measured during manufacturing…