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During execution of anti-drug antibody (ADA) testing it is common for laboratories to periodically exhaust their supply of negative control (NC) due to its multiple uses in an assay method. The NC is used for calculation of platespecific cut points, as a base pool for preparation of positive controls (PC), and as a diluent in the evaluation antibody titers. Whenever the NC is depleted, a new lot is needed to replace it. However, without appropriate upfront qualification of the replacement NC lot, issues can arise that complicate its implementation and use as a key critical reagent.

Ideally a new NC lot is generated in such a way that its performance is comparable to the previous lot that it is intended to replace. Unfortunately, simply combining matrix from multiple subjects to create a new pool of presumed antibody-free NC matrix seldom results in a new lot that performs similarly to the original. To aid the process of generating a new NC lot, we have devised a systematic approach that we believe increases the likelihood that the new NC lot will perform comparably to the previous one. Below are recommendations for screening matrix for NC lot generation, followed by NC qualification and cut point adjustment, if needed. For implementation of this NC preparation strategy, it is important to execute the work prior to completely depleting the original lot of NC.