Radioimmunometric assay for a monoclonal antibody-defined tumor marker, CA 19-9.

Authors:
  • BVB C Del Villano
    B C Del Villano
  • SBS Brennan
    S Brennan
  • PBP Brock
    P Brock
  • CBC Bucher
    C Bucher
  • VLV Liu
    V Liu
  • MMM McClure
    M McClure
  • BRB Rake
    B Rake
  • SSS Space
    S Space
  • BWB Westrick
    B Westrick
  • HSH Schoemaker
    H Schoemaker
  • VZV R Zurawski
    V R Zurawski
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Abstract
We describe a solid-phase radioimmunometric sandwich assay for a new tumor marker defined by a monoclonal antibody (19-9). This antibody reacts with a carbohydrate antigenic determinant (CA 19-9) found at low concentrations in sera from healthy individuals but frequently increased in sera from patients with adenocarcinomas. The assay is sensitive and simple to perform. It requires duplicate 100-microL samples and may be performed in 6 h. The concentration of CA 19-9 in samples is determined by reference to a standard curve, which is essentially linear from 0 to 120 arbitrary units/mL. The average CV is approximately 10% in the range of 5.8 to 120 units/mL. The minimum detectable dose is 1.4 units/mL and analytical recovery of CA 19-9 is 97.6 to 100.6%. The average concentration of CA 19-9 in sera from 1020 healthy individuals was 8.4 (SD 7.4) units/mL; only 0.6% of such sera had concentrations greater than 37 units/mL. The assay has high specificity (98.5%), even among patients with benign diseases, and has high sensitivity (up to 79%) for patients with gastrointestinal adenocarcinomas, especially those of the pancreas.