Ultrasensitive detection of prostate-specific antigen by a time- resolved immunofluorometric assay and the Immulite immunochemiluminescent third-generation assay: potential applications in prostate and breast cancers

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 42; no. 5; pp. 675 - 684
• Main Authors: Ferguson, RA, Yu, H, Kalyvas, M, Zammit, S, Diamandis, EP
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.05.1996; American Association for Clinical Chemistry
• Subjects: Biological and medical sciences; Breast Neoplasms - immunology; Cytosol - immunology; Drug Stability; Female; Fluoroimmunoassay - methods; Gynecology. Andrology. Obstetrics; Host-tumor relations. Immunology. Biological markers; Humans; Immunoassay - methods; Luminescent Measurements; Male; Mammary gland diseases; Medical sciences; Nephrology. Urinary tract diseases; Prostate-Specific Antigen - analysis; Prostate-Specific Antigen - blood; Prostatectomy; Prostatic Neoplasms - blood; Prostatic Neoplasms - surgery; Sensitivity and Specificity; Tumors; Tumors of the urinary system; Urinary tract. Prostate gland; Performance evaluation; Human; Prostate disease; Exploration; Chemiluminescence; Tumoral marker; Immunological method; Prostate specific antigen; Mammary gland diseases; Detection limit; Clinical biology; Tumor; Mammary gland; Immunofluorescence; Male genital diseases; Prostate; Quantitative analysis
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/42.5.675

We report an ultrasensitive time-resolved immunofluorometric assay (TRIFA) for prostate-specific antigen (PSA). The assay is an improvement of our previous report (Clin Chem 1993;39:2108-14) and includes the utilization of two monoclonal antibodies and a one-step incubation period, which greatly reduces analysis time. The new method demonstrates a superior lower analytical limit of detection (< or = 1 ng/L), a wide dynamic range, absence of a hook effect at 10(6) ng/L PSA, and equimolarity for free PSA and PSA-antichymotrypsin complex. Also, we have compared several aspects of our TRIFA with a commercially available third-generation assay (Immulite). An evaluation of breast tumor cytosol extracts from 315 patients shows PSA immunoreactivity > 15 ng/g of total protein in 28% and 23% by TRIFA and Immulite analysis, respectively. Both methods demonstrate a significant association between breast tumor PSA immunoreactivity and progesterone and estrogen receptor positivity (P <0.001). Analysis of serum samples obtained for monitoring of postradical prostatectomy patients reveals significant PSA changes at concentrations undetectable by conventional methods. The significance of these results as well as the potential applications of ultrasensitive PSA assays in breast and prostate cancers are discussed.