Immunoassay hapten heterology

Figure 1 Schematic of the quasi-equihbria using heterologous haptens in coating antigen immunoassay formats. Ka represents the equilibrium constant for binding of antibody (Y) to target analyte (A). Kh is the equilibrium constant for the binding of antibody to hapten-protein conjugate (H-) immobihzed on a solid phase...

Immunoassays for diuron (Figure 13) are another example of improved assay performance using heterologous assay conditions. One antibody was derived from a hapten that extended the dimethylamine side chain of diuron with methylene groups. 

Figure 13 Structures of haptens used for immunizing and coating antigens in a monoclonal antibody-based immunoassay for diuron. A sensitive assay was developed using coating hapten I that had the handle in a position different from the immunogen hapten. When the oxygen in the urea moiety of hapten I was replaced with a sulfur (hapten 11), increasing the heterology, even greater sensitivity was achieved...

In 1982, the first enzyme immunoassay of clenbuterol was described (134). It was used to determine clenbuterol levels in plasma of human patients treated by oral route with this drug. It was a highly sensitive double-antibody and heterologous immunoassay based on a competition for binding to a clenbuterol-specific antibody between a diazotized clenbuterol analogue labeled with -galactosidase and unlabeled standard or sample clenbuterol. The antibody-bound enzyme hapten was separated from free hapten by anti-rabbit IgG immobilized to a polystyrene ball. The assay could detect levels as low as 0.5 pg clenbuterol per tube. 

Lee, N., D.P. McAdam, and J.H. Skerritt. 1998. Development of immunoassays for type II synthetic pyrethroids. 1. Hapten design and application to heterologous and homologous assays. J. Agric. Food Chem. 46 520-534. 

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