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Immunoassay for the discrimination of free prostate-specific antigen (fPSA) forms with internal cleavages at Lys(145) or Lys(146) from fPSA without internal cleavages at Lys(145) or Lys(146)

Peltola, Mari T.; Niemela, Pauliina; Alanen, Kalle; Nurmi, Martti; Lilja, Hans LU and Pettersson, Kim (2011) In Journal of Immunological Methods 369(1-2). p.74-80
Abstract
Total levels of circulating prostate-specific antigen (tPSA) are strongly associated with prostate cancer (PCa) risk and outcome but benign prostate disease is the most frequent cause of a moderately elevated PSA level. Free PSA (fPSA) forms are independently associated with PCa risk and contribute modest diagnostic enhancements above and beyond tPSA alone. We developed an immunoassay for fPSA subfractions containing internal cleavages at Lys(145) or Lys(146) (fPSA-N). The assay was based on blocking intact single-chain fPSA (fPSA-I) with antibody 4D4 which does not detect PSA containing internal cleavages at Lys(145) or Lys(146). We also measured fPSA-N in blood from healthy volunteers and in anti-coagulated plasma from 76 men with or... (More)
Total levels of circulating prostate-specific antigen (tPSA) are strongly associated with prostate cancer (PCa) risk and outcome but benign prostate disease is the most frequent cause of a moderately elevated PSA level. Free PSA (fPSA) forms are independently associated with PCa risk and contribute modest diagnostic enhancements above and beyond tPSA alone. We developed an immunoassay for fPSA subfractions containing internal cleavages at Lys(145) or Lys(146) (fPSA-N). The assay was based on blocking intact single-chain fPSA (fPSA-I) with antibody 4D4 which does not detect PSA containing internal cleavages at Lys(145) or Lys(146). We also measured fPSA-N in blood from healthy volunteers and in anti-coagulated plasma from 76 men with or without evidence of PCa at biopsy. The analytical and functional detection limits of this assay were 0.016 ng/mL and 0.10 ng/mL, respectively. The median recovery of male fPSA-N from female plasma was 95.0%. All 12 female samples (average age 28 years) had fPSA-N concentrations at or below the analytical detection limit. The median fPSA-N concentration (0.050 ng/mL) in 9 healthy male volunteers (age <40 years) was below the functional detection limit, 0.420 ng/mL in 27 patients with benign prostate conditions and 0.239 ng/mL in 49 patients with PCa. Deming regression analysis of the patient samples showed that the measured fPSA-N concentrations were generally 23% lower than the previously calculated (fPSA minus fPSA-I) concentrations, likely due to differences in the antibody combinations used. In conclusion, we have developed a sensitive, specific and direct immunoassay for fPSA-N which can be used to study the clinical relevance of this PSA isoform. (C) 2011 Elsevier B.V. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Prostate-specific antigen, Free PSA isoform, Internally cleaved PSA, Nicked PSA, Immunoassay, Prostate cancer
in
Journal of Immunological Methods
volume
369
issue
1-2
pages
74 - 80
publisher
Elsevier
external identifiers
  • wos:000292799000008
  • scopus:79958838315
ISSN
1872-7905
DOI
10.1016/j.jim.2011.04.006
language
English
LU publication?
yes
id
f3f49e0b-9dcc-4622-897c-afe9d5c264fa (old id 2094077)
date added to LUP
2011-09-02 08:35:24
date last changed
2017-04-16 03:53:24
@article{f3f49e0b-9dcc-4622-897c-afe9d5c264fa,
  abstract     = {Total levels of circulating prostate-specific antigen (tPSA) are strongly associated with prostate cancer (PCa) risk and outcome but benign prostate disease is the most frequent cause of a moderately elevated PSA level. Free PSA (fPSA) forms are independently associated with PCa risk and contribute modest diagnostic enhancements above and beyond tPSA alone. We developed an immunoassay for fPSA subfractions containing internal cleavages at Lys(145) or Lys(146) (fPSA-N). The assay was based on blocking intact single-chain fPSA (fPSA-I) with antibody 4D4 which does not detect PSA containing internal cleavages at Lys(145) or Lys(146). We also measured fPSA-N in blood from healthy volunteers and in anti-coagulated plasma from 76 men with or without evidence of PCa at biopsy. The analytical and functional detection limits of this assay were 0.016 ng/mL and 0.10 ng/mL, respectively. The median recovery of male fPSA-N from female plasma was 95.0%. All 12 female samples (average age 28 years) had fPSA-N concentrations at or below the analytical detection limit. The median fPSA-N concentration (0.050 ng/mL) in 9 healthy male volunteers (age &lt;40 years) was below the functional detection limit, 0.420 ng/mL in 27 patients with benign prostate conditions and 0.239 ng/mL in 49 patients with PCa. Deming regression analysis of the patient samples showed that the measured fPSA-N concentrations were generally 23% lower than the previously calculated (fPSA minus fPSA-I) concentrations, likely due to differences in the antibody combinations used. In conclusion, we have developed a sensitive, specific and direct immunoassay for fPSA-N which can be used to study the clinical relevance of this PSA isoform. (C) 2011 Elsevier B.V. All rights reserved.},
  author       = {Peltola, Mari T. and Niemela, Pauliina and Alanen, Kalle and Nurmi, Martti and Lilja, Hans and Pettersson, Kim},
  issn         = {1872-7905},
  keyword      = {Prostate-specific antigen,Free PSA isoform,Internally cleaved PSA,Nicked PSA,Immunoassay,Prostate cancer},
  language     = {eng},
  number       = {1-2},
  pages        = {74--80},
  publisher    = {Elsevier},
  series       = {Journal of Immunological Methods},
  title        = {Immunoassay for the discrimination of free prostate-specific antigen (fPSA) forms with internal cleavages at Lys(145) or Lys(146) from fPSA without internal cleavages at Lys(145) or Lys(146)},
  url          = {http://dx.doi.org/10.1016/j.jim.2011.04.006},
  volume       = {369},
  year         = {2011},
}