BACKGROUND: Prostate-specific antigen (PSA) occurs in serum both free and in complex with protease inhibitors. The complex with alpha1-antichymotrypsin (ACT) is the major form in serum, and the proportion of PSA-ACT is higher in prostate cancer (PCa) than in benign prostatic hyperplasia (BPH). PSA also forms a complex with alpha1-protease inhibitor (API) in vitro, and the PSA-ACT complex has been detected in serum from patients with prostate cancer. The aim of the present study was to develop a quantitative method for the determination of PSA-API and to determine the serum concentrations in patients with PCa and BPH. METHODS: The assay for PSA-API utilizes a monoclonal antibody to PSA as capture and a polyclonal antibody to API labeled with a Eu-chelate as a tracer. For calibrators, PSA-API formed in vitro was used. Serum samples were obtained before treatment from 82 patients with PCa, from 66 patients with BPH, and from 22 healthy females. RESULTS: The concentrations of PSA-API are proportional to the concentrations of total PSA. PSA-API comprises 1.0-7.9% (median, 2.4%) of total immunoreactive PSA in PCa and 1.3-12.2% (median, 3.6%) in BPH patients with serum PSA concentrations >4 microgram/L. In patients with 4-20 microgram/L total PSA, the proportion of PSA-API serum is significantly higher in BPH (median, 4.1%) than in PCa (median, 3. 2%; P = 0.02). CONCLUSIONS: The proportion of PSA-API in serum is lower in patients with PCa than in those with BPH. These results suggest that PSA-API is a potential adjunct to total and free PSA in the diagnosis of prostate cancer.
BACKGROUND:Prostate-specific antigen (PSA) occurs in serum both free and in complex with protease inhibitors. The complex with alpha1-antichymotrypsin (ACT) is the major form in serum, and the proportion of PSA-ACT is higher in prostate cancer (PCa) than in benign prostatic hyperplasia (BPH). PSA also forms a complex with alpha1-protease inhibitor (API) in vitro, and the PSA-ACT complex has been detected in serum from patients with prostate cancer. The aim of the present study was to develop a quantitative method for the determination of PSA-API and to determine the serum concentrations in patients with PCa and BPH. METHODS: The assay for PSA-API utilizes a monoclonal antibody to PSA as capture and a polyclonal antibody to API labeled with a Eu-chelate as a tracer. For calibrators, PSA-API formed in vitro was used. Serum samples were obtained before treatment from 82 patients with PCa, from 66 patients with BPH, and from 22 healthy females. RESULTS: The concentrations of PSA-API are proportional to the concentrations of total PSA. PSA-API comprises 1.0-7.9% (median, 2.4%) of total immunoreactive PSA in PCa and 1.3-12.2% (median, 3.6%) in BPH patients with serum PSA concentrations >4 microgram/L. In patients with 4-20 microgram/L total PSA, the proportion of PSA-API serum is significantly higher in BPH (median, 4.1%) than in PCa (median, 3. 2%; P = 0.02). CONCLUSIONS: The proportion of PSA-API in serum is lower in patients with PCa than in those with BPH. These results suggest that PSA-API is a potential adjunct to total and free PSA in the diagnosis of prostate cancer.
Authors: B Bindukumar; Stanley A Schwartz; Madhavan P N Nair; Ravikumar Aalinkeel; Elzbieta Kawinski; Kailash C Chadha Journal: Neoplasia Date: 2005-03 Impact factor: 5.715