Characterization of an ELISA standard

Comparing the Host Cell Protein content in mock and harvest samples


Before developing a custom process-specific HCP ELISA, our client wished to confirm the suitability of their mock sample for this purpose. LC-MS analysis showed that the mock sample only contained 65% of the HCPs found in the harvest sample, making it unsuitable for generating process-specific ELISA antibodies. These findings saved them from spending time and resources developing an ELISA with low coverage.

This EU-based biopharmaceuticals development and manufacturing company wished to compare the Host Cell Protein (HCP) impurities in their harvest and mock samples. Furthermore, they wanted an evaluation of the mock sample’s suitability for application as an HCP ELISA Standard in developing a process-specific HCP ELISA that could detect the majority of HCPs in the final drug substance.


The protein profile of the mock sample used to develop ELISA antibodies for a process-specific ELISA must represent the Host Cell Proteins in the harvest sample. Otherwise, the ELISA will not be capable of detecting the (majority of) HCPs in the final drug substance. However, mock samples are not always true to the producing line sample. Characterizing the resemblance between mock and harvest samples is, therefore, necessary to determine whether the resulting custom ELISA will fit for purpose.


An HCP analysis using the Alphalyse LC-MS approach found that the client’s mock sample contained only 65% of the HCPs in the harvest sample, making it unsuitable for generating process-specific ELISA antibodies.

Comparison of host cell proteins present in a mock sample
and the corresponding harvest sample

These findings saved our client from developing an ELISA that would most likely have low coverage.

In addition, we analyzed a batch of the client’s drug substance and the standard provided with their commercial ELISA kit. The commercial ELISA standard contained 92% of the HCPs identified in the harvest sample, including all 7 HCPs found in the final drug substance. Therefore, our client is now considering using this standard in the late-stage clinical phases instead of the mock sample.  

The coverage percentage of the client’s commercial ELISA standard and
list of the specific HCPs of concern identified

EU-based CDMO_logo
"The data showed that our mock was unsuitable and thus saved us from developing a process-specific ELSA with low coverage of the HCPs in our drug product"

EU-based CDMO- Managing Partner

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