title: Time-resolved immunofluorometric assay of trypsin-1 complexed with alpha(1)-antitrypsin in serum: increased immunoreactivity in patients with biliary tract cancer.
abstract: BACKGROUND
  Increased serum concentrations of trypsin immunoreactivity occur in patients with biliary tract cancer. To characterize this trypsin, we developed a sensitive time-resolved immunofluorometric assay for trypsin-1 complexed with alpha(1)-antitrypsin (AAT) and studied the concentrations of this complex in sera from healthy individuals (n = 130) and patients with benign biliary disease (n = 32), biliary tract cancer (n = 17), pancreatic cancer (n = 27), and hepatocellular cancer (n = 12).
  
  
  METHODS
  We used a trypsin-1-specific monoclonal antibody on the solid phase and a europium-labeled polyclonal antibody to AAT as tracer. The detection limit was 0.42 microgram/L. The validity of the trypsin-1-AAT test for detection of biliary tract cancer was compared with trypsin-2-AAT and CA19-9.
  
  
  RESULTS
  Increased concentrations of trypsin-1-AAT (>33 microgram/L) were found in 76% of patients with biliary tract cancer, and the concentrations were significantly higher than in those with benign biliary disease (P <0. 0001). The median concentration of trypsin-1-AAT in serum from patients with biliary tract cancer was 3.7-fold higher than in healthy controls, 2.6-fold higher than in patients with benign biliary tract disease, 1.7-fold higher than in patients with pancreatic cancer, and 2.0-fold higher than in patients with hepatocellular cancer.
  
  
  CONCLUSIONS
  Of the markers studied, trypsin-1-AAT had the largest area (0.83) under the receiver operating curve in differentiating biliary tract cancer from benign biliary tract disease. Our results suggest that trypsin-1-AAT is a new potential marker for biliary tract cancer.
authors.affiliation: Department of Clinical Chemistry, University of Helsinki, FIN-00029 Helsinki, Finland. johan.hedstrom@huch.fi
authors.forename: J
authors.initials: J
authors.lastname: Hedström
authors.forename: C
authors.initials: C
authors.lastname: Haglund
authors.forename: E
authors.initials: E
authors.lastname: Kemppainen
authors.forename: M
authors.initials: M
authors.lastname: Leinimaa
authors.forename: J
authors.initials: J
authors.lastname: Leinonen
authors.forename: U H
authors.initials: UH
authors.lastname: Stenman
mesh_terms: D001660:Biliary Tract Diseases / Q000097:blood; D001661:Biliary Tract Neoplasms / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood; D018395:CA-19-9 Antigen / Q000097:blood; D015200:Fluoroimmunoassay / Q000379:methods; D006801:Humans; D007527:Isoenzymes / Q000097:blood; D010190:Pancreatic Neoplasms / Q000097:blood; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014357:Trypsin / Q000097:blood*; D014362:Trypsinogen / Q000097:blood; D000515:alpha 1-Antitrypsin / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D018395:CA-19-9 Antigen; D007527:Isoenzymes; D000515:alpha 1-Antitrypsin; D014362:Trypsinogen; D014357:Trypsin