title: Validation and comparison of tumor-associated trypsin inhibitor (TATI) immunoassays.
abstract: BACKGROUND
  Tumor-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.
  
  
  METHODS
  We 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.
  
  
  RESULTS
  The assay range and precision were 0.8-45 μg/L and <9.1% for the ELISA, and 0.13 μg/L-150 μg/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 4 weeks and at -80°C for 8 weeks. The 95% reference limits for serum TATI in adults were 5.2-15.3 μg/L in the age group 18-70 years and 7.5-21.3 μg/L in the age group >70 years.
  
  
  CONCLUSIONS
  Significantly 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.
authors.affiliation: Department of Clinical Chemistry, University of Helsinki, Helsinki, Finland.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Janeiro
authors.forename: Joana
authors.initials: J
authors.lastname: Guimarães
authors.forename: Ulf-Håkan
authors.initials: UH
authors.lastname: Stenman
authors.forename: Manuela
authors.initials: M
authors.lastname: Catarino
authors.forename: Outi
authors.initials: O
authors.lastname: Itkonen
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002138:Calibration; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D012016:Reference Values; D012680:Sensitivity and Specificity; D014359:Trypsin Inhibitor, Kazal Pancreatic / Q000097:blood*; D055815:Young Adult
chemical_list: D014359:Trypsin Inhibitor, Kazal Pancreatic