Standardization of immunoassays for hapten analytes.

The pace of the development and commercialization of immunoassay methodology has been so great, that the parallel development of ways to ensure comparability between the results of different immunoassays for the same substance has fallen behind. If, as is the case with many hapten analytes, the analyte is chemically defined, homogeneous and available at very high purity, the rigorous standardization of different immunoassays developed to determine the same would appear to be feasible. However, many published details of external quality assessment schemes and of studies on the comparability of commercial assays indicate that the results of immunoassays for hapten analytes are not generally and reliably comparable. Lack of comparability is most marked for assays detecting a variety of analyte subforms or metabolites. This problem is surveyed with respect to the variability of hapten immunoassays, factors related to details of immunoassays. Finally, the assessment of assay comparability and some potential strategies for improving it are discussed.