title: Development of time-resolved immunofluorometric assays for CA 72-4 and application in sera of patients with gastric tumors.
abstract: BACKGROUND
  Immunoradioassay (IRMA) with (125)I-labeled monoclonal antibodies is widely used to measure levels of cancer antigen (CA) 72-4. We investigated a time-resolved immunofluorometric assay (TR-IFMA) to determine its sensitivity and specificity compared with those of IRMA.
  
  
  METHODS
  We used 2 CA 72-4-specific monoclonal antibodies with different specificities. One was immobilized on a solid phase, and one was labeled with Eu(3+). Serum from 44 adults with newly diagnosed gastric cancer and 208 control subjects was assayed by TR-IFMA and a conventional IRMA.
  
  
  RESULTS
  The detection limit of TR-IFMA was 0.55 U/ml. The calibration curve was linear to 1000 U/ml, with no hook effect up to 1000 U/ml. Intraassay CVs were 4.2-10.26% over the calibration range. Compared with IRMA, TR-IFMA had a broader analytical range and a shorter analysis time. At a cutoff of 99% specificity, TR-IFMA and IRMA results were positive in 37 and 26 patients, respectively.
  
  
  CONCLUSIONS
  TR-IFMA is a rapid and sensitive nonradioactive method applicable to large-scale screening for CA 72-4. In addition to its broad, linear analytical range, TR-IFMA was more sensitive and specific than conventional IRMA. It was easy to perform and automate.
authors.affiliation: Department of Nuclear Medicine, Renji Hospital, Shanghai JiaoTong University School of Medicine, Shanghai 200001, China.
authors.forename: Shi Le
authors.initials: SL
authors.lastname: Sheng
authors.forename: Qing
authors.initials: Q
authors.lastname: Wang
authors.forename: Gang
authors.initials: G
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000097:blood*; D002138:Calibration; D005260:Female; D015200:Fluoroimmunoassay; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000097:blood*
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; C083825:CA-72-4 antigen