Method qualification of an electrochemiluminescence assay to quantitate anti-FcεR1α autoantibodies: a case study of an antibody-based biomarker

Chronic spontaneous urticaria is a common immunological disease that affects over 1% of the population. Recently, the anti-FcεR1α autoantibody has been discovered as a prominent biomarker related to the disease. Therefore, there is a need for robust, qualified assays to characterize and measure anti-FcεR1α autoantibodies in human serum. However, biomarker assay qualification is a topic of discussion and can sometimes be left open to interpretation. Currently, there is little guidance or best practices outlined for the method qualification of autoantibodies. These molecules are typically endogenous and such assays fall somewhere between quantitative and qualitative.Herein, we develop an electrochemiluminescence assay for the detection of anti-FcεR1α autoantibodies and provide an outline of method qualification. Two assay formats are investigated with one being fully developed and optimized. Other considerations stemming from immunogenicity qualifications are also assessed, such as isotyping, cut-point, and a confirmatory assay.