Development of time-resolved immunofluorometric assays for CA 72-4 and application in sera of patients with gastric tumors.
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.
Sheng
Shi Le
SL
Department of Nuclear Medicine, Renji Hospital, Shanghai JiaoTong University School of Medicine, Shanghai 200001, China.
Wang
Qing
Q
Huang
Gang
G
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*
D015295:Antigens, Tumor-Associated, Carbohydrate; C083825:CA-72-4 antigen