Chapter 6 - Immunoassay Design and Mechanisms of Interferences

Abstract

Immunoassays are routinely used for analysis of a large number of analytes tested in clinical laboratories, and these assays use photometric, luminometric, or fluorometric signals and homogeneous or heterogeneous formats. Serum and plasma are the main specimen types used for immunoassays, although alternate types of specimens have also been used. Although immunoassays exhibit excellent sensitivity and specificity, a major limitation of immunoassays is interference from various endogenous (heterophilic antibody, rheumatoid factors, high bilirubin, etc.) and exogenous factors (drug metabolites and structurally similar compounds) that may falsely elevate or reduce the true value of the analyte. There are various ways of detecting such false-positive or false-negative results and eliminating such interferences in immunoassays to obtain accurate results. In this chapter, the focus is on eliminating interferences from heterophilic and autoantibodies.