Approaches to Minimizing Interference by Cross-Reacting Molecules in Immunoassays

Here we review techniques useful in eliminating or reduc-ing interferences caused by molecules that cross-react in immunoassays. The biochemical rationale for usingthese techniques is discussed. Examples are taken from recent studies aimed at reducing interferences caused by endog-enous molecules such as digoxin-like immunoreactive factors or steroid hormones. In this context the role of protein-binding of cross-reacting molecules is also con-sidered. Immunoassay ligand selectivity can be inherently limited by the heterogeneity of the antigenic response or by the structural similarity of epitopes on multiple ligands. Certain empirical approaches have proved useful in max-imizing the analytical specificity of immunoassays. These approaches include isolating the relevant ligands before immunoassay, adjusting the kinetic or equilibrium condi