Dual-label one-step immunoassay for simultaneous measurement of free and total prostate-specific antigen concentrations and ratios in serum.
We developed a simple one-step dual-label immunoassay for simultaneous measurement of the free, noncomplexed form of prostate-specific antigen (PSA) and total PSA. The assay is based on time-resolved fluorescence and includes a stable fluorescent chelate of Eu to label a monoclonal antibody (mAb) that detects only free PSA, whereas a second mAb labeled with a fluorescent chelate of Tb provides equimolar detection of both free PSA and PSA complexed to alpha 1-antichymotrypsin. A third mAb on a solid phase captures the free and complexed forms of PSA in an equimolar fashion. The simultaneous measurement of the free-to-total PSA ratio (F/T) with the one-step dual assay is not sensitive to variations in the sample volume. The discrimination between benign prostatic hyperplasia and prostate cancer patients, i.e., the area under the receiver-operating characteristic curve, increased from 0.64 (total PSA assay) to 0.78 and 0.81 when the F/T ratio was measured with single and dual assays, respectively.
Mitrunen
K
K
Department of Biotechnology, University of Turku, Finland.
Pettersson
K
K
Piironen
T
T
Björk
T
T
Lilja
H
H
Lövgren
T
T
D000911:Antibodies, Monoclonal; D005063:Europium; D005260:Female; D005455:Fluorescent Antibody Technique / Q000706:statistics & numerical data; D006801:Humans; D007700:Kinetics; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood; D012680:Sensitivity and Specificity; D000514:alpha 1-Antichymotrypsin / Q000378:metabolism
D000911:Antibodies, Monoclonal; D000514:alpha 1-Antichymotrypsin; D005063:Europium; D017430:Prostate-Specific Antigen