Validation and comparison of tumor-associated trypsin inhibitor (TATI) immunoassays

Abstract

BackgroundTumor-associated trypsin inhibitor (TATI) is mainly proposed as a tumor marker for ovarian cancer. However, recent discoveries of TATI in cancer and inflammatory diseases show that assay of TATI in biological samples is of increasing interest. MethodsWe validated a previously described TR-IFMA and a newly developed dual-monoclonal sandwich ELISA for TATI. These methods were compared with a commercial radioimmunoassay (RIA). We studied preanalytical factors affecting serum TATI concentrations and established age- and gender specific reference intervals using serum samples from 195 healthy volunteers. ResultsThe assay range and precision were 0.8–45μg/L and <9.1% for the ELISA, and 0.13μg/L–150μg/L and <12.5% for the TR-IFMA, respectively. Both assays correlated well with a RIA. Type of blood sample and nutritional status were not critical and TATI was stable in serum samples when stored at +4°C and −20°C for 4weeks and at −80°C for 8weeks. The 95% reference limits for serum TATI in adults were 5.2–15.3μg/L in the age group 18–70years and 7.5–21.3μg/L in the age group >70years. ConclusionsSignificantly higher concentrations of serum TATI were observed in elderly women and in men. Both ELISA and TR-IFMA technologies can be employed to develop sensitive and robust immunoassays for TATI using monoclonal antibodies.