Multiple forms of prostate-specific antigen in serum: differences in immunorecognition by monoclonal and polyclonal assays

Zhou, Anna; Tewari, Prakash C.; Bluestein, Barry I.; Caldwell, Gary W.; Larsen, Frank Wugt

doi:10.1093/clinchem/39.12.2483

Cited by 117 publications

(21 citation statements)

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“…This is because of differences in the recognition of epitopes of PSA by different types of immunoassays, i.e., monoclonal-mono-clonal sandwich assays versus monoclonal-polyclonal and polyclonal-polyclonal types of sandwich assays. Different forms of PSA (e.g., free seminal plasma PSA or PSA complexed with the protease inhibitor alpha,-antichymotrypsin) display different ratios of PSA epitopes, resulting in differential detection of different molecular forms of PSA among the various types of assays [21]. Stenman et al [15] and Lilja et al [16] determined that current PSA tests detect two forms of PSA in serum, a low molecular weight free PSA and PSA complexed to alpha-1-antichymotrypsin (PSA-ACT), and that PSA-ACT is the predominant form of PSA in serum [15,16].…”

Section: Discussionmentioning

confidence: 99%

Identity of PSA purified from seminal fluid by different methods: Comparison by amino acid analysis and assigned extinction coefficients

1995

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To determine the true extinction coefficient of prostate specific antigen (PSA) and to measure any differences in PSA when isolated from seminal fluid by four different published methods, we studied 10 different lots of PSA by quantitative amino acid analysis. Despite an expected PSA concentration of 1 mg/ml based on gravimetric analysis at an average optical density of 1.45 at 280 nm, we recovered only 0.79 mg/ml by quantitative amino acid analysis (range 0.752 to 0.820 mg/ml with a coefficient of variation [C.V.] of 3.3% among the 10 lots). The concentration of 0.79 mg/ml was based on a molecular weight of 28,430 daltons for glycosylated PSA determined by ion spray mass spectroscopy [Bélanger et al: Prostate, 27:187-197, 1995]. From these 10 amino acid analyses, we calculated the extinction coefficient of PSA at 280 nm as 1.84 +/- 0.04 ml x mg-1 x cm-1 (range 1.78 to 1.90 with a C.V. of 2.2%). Similar concentrations of PSA were obtained by amino acid analysis regardless of the method of purification. These observations support the presence of a single form of PSA in seminal fluid and are consistent with the molecular evidence that PSA is transcribed from a single gene locus on the long arm of chromosome 19 [Riegman et al.: Genomics 14:6-11, 1992]. They do not support the recent contention by the Roswell Park group that the PSA they isolated in 1979 [Wang et al.: Invest Urol 17:159-163, 1979; Wang et al.: Prostate 24:107-108, 1994] is different from p30 reported a year earlier [Sensabaugh: J Forensic Sci 23:106-115, 1978].

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Section: Discussionmentioning

confidence: 99%

Identity of PSA purified from seminal fluid by different methods: Comparison by amino acid analysis and assigned extinction coefficients

1995

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“…The larger molecular size of PSA in serum is due in large part to its being complexed with the protease inhibitor a,-antichymotrypsin (Lilja et al, 1991;Stenman et al, 1991). PSA is also complexed with a,-macroglobulin as demonstrated by Western blotting; however, the high molecular weight PSA-o!,-macroglobulin complex could not be detected by commercial PSA immunoassays following gel filtration chromatography (Zhou et al, 1993). In general, BPH patients have a higher proportion of uncomplexed PSA ( 3 5 4 5 % of total PSA) than is found for men with prostate cancer (about 15% uncomplexed, a factor which may prove helpful in differentiating BPH and cancer) (Christensson et al, 1993;Stenman et al, 1991;Zhou et al, 1993).…”

Section: Proteases In Prostate Diseasementioning

confidence: 96%

“…PSA is also complexed with a,-macroglobulin as demonstrated by Western blotting; however, the high molecular weight PSA-o!,-macroglobulin complex could not be detected by commercial PSA immunoassays following gel filtration chromatography (Zhou et al, 1993). In general, BPH patients have a higher proportion of uncomplexed PSA ( 3 5 4 5 % of total PSA) than is found for men with prostate cancer (about 15% uncomplexed, a factor which may prove helpful in differentiating BPH and cancer) (Christensson et al, 1993;Stenman et al, 1991;Zhou et al, 1993). However, about 12% of cancer patients demonstrate a reversed ratio of uncomplexed and complexed PSA (Lilja et al, 1991).…”

Section: Proteases In Prostate Diseasementioning

confidence: 96%

Proteases in prostate development, function, and pathology

Wilson

1995

Microscopy Res & Technique

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INTRODUCTIONThe prostate gland and its secretions have long been known to contain a variety of potent proteolytic activities (Mann and Lutwak-Mann, 1981). The functions of these proteases and peptidases in the control of normal cellular operations in the prostate gland (especially as affected by androgens), in the steps of tumor progression in prostate cancer, and in interacting with sperm and seminal constituents secreted by other accessory glands into the semen are not understood. The proteases secreted into the semen have been postulated to degrade seminal proteins, especially to produce liquefaction of seminal coagulum in humans, and to possibly interact with sperm so as to modify their cell surfaces and affect their fertilizing ability. Recently, more attention has been given to prostatic proteases that can modify extracellular matrix proteins and especially in relation to tissue organization changes that occur during normal growth in prostate development and in the generation of pathology in prostate diseases. Proteases and peptidases of each catalytic group (i.e., serine, cysteine, aspartic, and metalloproteases) are produced by the prostate and are found in its secretions. Although a number of amino-and carboxy-exopeptidases and serine and metallopeptidases active towards small peptides are produced by the prostate and may have important functions in the gland and in its secretion, this review will focus on our present understanding of the roles of proteases (endopeptidases that cleave internal peptide bonds in proteins) in the development of the prostate, in its secretions, and in the generation of pathology that commonly occurs with aging in the gland.

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“…12 Anti-PSA antibodies of commercially available PSA assay kits have different characteristics of immunoreactivity to PSA-ACT and free PSA. [13][14][15] If a different PSA kit is used, the clinical usefulness of g-Sm ratio may alter. The g-Sm ratio has been rarely re-evaluated when using other PSA assays.…”

Section: Introductionmentioning

confidence: 99%

Ratio of gamma‐seminoprotein to prostate‐specific antigen for the detection of prostate cancer: Its discrimination power could be influenced by the assay methods of PSA and/or gamma‐seminoprotein

et al. 1999

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Background: The ratio of gamma-seminoprotein (g-Sm) and prostate-specific antigen (PSA) has been regarded as being superior over PSA alone as a discriminator between prostate cancer and benign prostatic diseases. In previous studies, PSA and g-Sm were measured by the Eiken kit and the old-version or revised Chugai kit, respectively. We compared the power of g-Sm ratio with that of PSA alone when using Markit-M PSA assay and the revised Chugai g-Sm assay. Methods: Fifty-three patients with prostate cancer having no metastasis and 116 with benign prostatic diseases were enrolled in this study. Prostate-specific antigen was measured by Markit-M kit and g-Sm was measured by the revised Chugai kit. The discrimination power of g-Sm ratio and PSA alone was evaluated with receiver operating characteristic (ROC) curves. Comparisons between prostate cancer and benign diseases were performed with Mann-Whitney U-test and Fisher's exact test. Results:The optimal cut-off value was set at 3.1 ng/mL for PSA and 0.935 for g-Sm ratio. Sensitivity, specificity and positive predictive value of PSA alone were 81.1, 81.0 and 66.2%, respectively, while those of g-Sm ratio were 73.6, 90.5 and 78.0%, respectively. There was no statistical significance in each value between PSA and g-Sm ratio. Areas under the ROC curves of PSA and g-Sm ratio were 0.881 and 0.866, respectively (P > 0.05). Conclusion: Contrary to the previous reports, g-Sm ratio and PSA were not different in the discrimination between prostate cancer and benign prostatic diseases, which suggested that the discrimination power of g-Sm ratio, and presumably that of the free PSA to total PSA ratio as well, could be considerably influenced by the assay kits for serum PSA and/or g-Sm (free PSA) used. Therefore, the clinical significance of g-Sm ratio should be evaluated for each PSA assay kit.

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Multiple forms of prostate-specific antigen in serum: differences in immunorecognition by monoclonal and polyclonal assays

Cited by 117 publications

References 0 publications

Identity of PSA purified from seminal fluid by different methods: Comparison by amino acid analysis and assigned extinction coefficients

Identity of PSA purified from seminal fluid by different methods: Comparison by amino acid analysis and assigned extinction coefficients

Proteases in prostate development, function, and pathology

Ratio of gamma‐seminoprotein to prostate‐specific antigen for the detection of prostate cancer: Its discrimination power could be influenced by the assay methods of PSA and/or gamma‐seminoprotein

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