Development of a new Prolifigen TPA IRMA assay using monoclonal anti-cytokeratin antibodies.

A new immunoassay for TPA determination has been developed in which anticytokeratin monoclonal antibodies are used. A three-Mab combination with different anticytokeratin antibody specificities has been selected to mimic the complex pattern found for the polyclonal anti-TPA antibody. The accuracy of the assay is good, as judged from analytical-recovery experiments, analysis of quality-assessment samples and comparison with the polyclonal Prolifigen TPA IRMA. No significant interferences or cross-reactivities have been identified. The lower limit of detection of the assay (mean + 3 SD of the zero standard) is below 15 U/L and the imprecision in low, giving a working range of 15-4000 U/L. The improved handling of the assay, including a single incubation step of 2 hours with shaking at room temperature, results in a narrower normal distribution, thereby giving a better separation of normal and pathological samples.