Prostate Cancer Biomarkers Detected by Immunoassay

Both free prostate specific antigen (fPSA) and total prostate specific antigen (tPSA) can be detected in a serum sample at the same time.

A flexible bead-based immunoassay, employing two mouse monoclonal antibodies has been developed that will rapidly measure tPSA and fPSA simultaneously and has compared favorably with conventional methods.

The method was developed by scientists at Fudan University, (Shanghai, China) who measured the PSA levels in serum obtained from 120 healthy donors and 94 patients examined for suspected prostate cancer. They used the Luminex xMAP bead array technology (Luminex, Austin, TX, USA), to measure tPSA and fPSA at one time, employing two mouse monoclonal anti-PSA antibodies (5G6 and 8A6) for coating and another mouse monoclonal anti-PSA antibody (5A6) for detection.

In blood samples from 120 healthy donors, the tPSA and fPSA concentration ranged from 0.2 ng/mL to 5.6 ng/mL and from 0.1 ng/mL to 1.3 ng/mL with a median of 1.9 ng/mL and 0.3 ng/mL, respectively. In blood samples from 94 suspected prostate cancer patients, the tPSA and fPSA concentration ranged from 0.8 ng/mL to 156.6 ng/mL and from 0.1 ng/mL to 18.5 ng/mL with a median of 9.3 ng/mL and 1.2 ng/mL, respectively. The lower detection limits of tPSA and fPSA in the assay were found to be 2.3 ng/mL and 1.3 pg/mL, respectively. The 120 healthy donors' sera and 94 suspected prostate cancer patients' sera were retested with the conventional enzyme-linked immunosorbent assay (ELISA) technique. For both healthy group and the suspected cancer group, a close correlation between the two assays was observed.

The scientists concluded that the bead-based platform is a rapid, sensitive, and less expensive assay, which allows for both single sample and high-throughput measurement of tPSA and fPSA over a wide range of concentrations. The study was published online on January 19, 2011 in the Journal of Clinical Laboratory Analysis.

Related Links:
Fudan University
Luminex