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Quantitative immunoassay for complexes of prostate-specific antigen with alpha2-macroglobulin
F España1, J Sánchez-Cuenca, A Estellés
1Research Center, La Fe Univesity Hospital, Valencia, Spain.
Clinical Chemistry
|April 1, 1996
Summary
New ELISAs accurately measure prostate-specific antigen (PSA) complexed with alpha2-macroglobulin (alpha2M) in various bodily fluids. These assays show potential for detecting PSA:alpha2M complexes in patients with prostate disease.
Area of Science:
- Biochemistry
- Analytical Chemistry
- Urology
Background:
- Prostate-specific antigen (PSA) is a key biomarker for prostate health.
- Understanding PSA complexation with other proteins like alpha2-macroglobulin (alpha2M) is crucial for accurate diagnostics.
- Existing methods may not adequately quantify PSA:alpha2M complexes in diverse biological matrices.
Purpose of the Study:
- To develop and validate two distinct Enzyme-Linked Immunosorbent Assays (ELISAs) for quantifying prostate-specific antigen complexed with alpha2-macroglobulin (PSA:alpha2M).
- To adapt assays for specific biological fluids: one for semen with excess PSA, another for blood plasma with excess alpha2M.
- To assess the concentration of PSA:alpha2M complexes in seminal fluid and plasma from healthy individuals and prostate disease patients.
Main Methods:
- Development of two specific ELISAs using a partially purified PSA:alpha2M complex as the calibrator.
- Assay validation for quantification range (2-1000 µg/L), detection limit (3 µg/L), and precision (intra-assay CVs 7-13%, inter-assay CVs 11-17%).
- Analysis of PSA:alpha2M complex levels in seminal fluid, prostatic fluid, seminal vesicle fluid, and plasma from healthy subjects and patients with prostate disease.
Main Results:
- Developed ELISAs with a quantification range of 2-1000 µg/L and a detection limit of 3 µg/L.
- Healthy seminal fluid showed mean PSA:alpha2M levels of 5.2 ± 2.6 µg/L.
- In plasma, purified PSA formed complexes with alpha2M (approx. 25%), alpha1-antichymotrypsin (10%), and other inhibitors.
- Twenty out of 30 prostate disease patients exhibited detectable plasma PSA:alpha2M complexes.
Conclusions:
- Successfully developed sensitive and precise ELISAs for quantifying PSA:alpha2M complexes in semen and plasma.
- Established baseline levels of PSA:alpha2M in seminal and prostatic fluids of healthy men.
- Identified detectable plasma PSA:alpha2M complexes in a majority of prostate disease patients, suggesting potential diagnostic utility requiring further investigation.