A robust immunoassay for pregnancy-associated plasma protein-A2 based on analysis of circulating antigen: establishment of normal ranges in pregnancy.

Pregnancy-associated plasma protein-A (PAPP-A) and PAPP-A2, two homologous metzincin metalloproteases, are both tightly linked to regulation within the insulin-like growth factor (IGF) system because of their specific cleavage of IGF binding proteins. Recent studies suggest that PAPP-A may be involved in clinical conditions related to unwanted cellular growth, and the circulating levels of PAPP-A is an established biomarker in prenatal screening for chromosomal abnormalities. Microarray data indicate that PAPP-A2 has potential as a biomarker for pre-eclampsia. However, well-characterized immunological methods of quantification are not available. We therefore developed monoclonal antibodies against recombinant PAPP-A2. The antibodies were epitope mapped against recombinantly expressed chimeras between PAPP-A2 and PAPP-A. Furthermore, circulating PAPP-A2 was immunoaffinity purified and characterized by sequence analysis and mass spectrometry. Unlike PAPP-A, PAPP-A2 is a noncovalent dimer in which each subunit of 1558 amino acids originates from all of the 22 predicted coding exons. A previously hypothesized variant (PAPP-E) does not exist, but low amounts of a C-terminally truncated PAPP-A2 variant was detected. A sensitive and robust ELISA for full-length PAPP-A2 was developed and used to establish normal ranges of PAPP-A2 through pregnancy. The functional sensitivity of this ELISA at 20% CV was 0.08 ng/ml, and the serum concentration of PAPP-A2 was found to increase during pregnancy in agreement with placental synthesis. The existence of this assay will enable an assessment of the biomarker potential of PAPP-A2 in pre-eclampsia as well as other clinical conditions.
AuthorsS Kløverpris, E Gaidamauskas, L C V Rasmussen, M T Overgaard, C Kronborg, U B Knudsen, M Christiansen, A Kumar, C Oxvig
JournalMolecular human reproduction (Mol Hum Reprod) Vol. 19 Issue 11 Pg. 756-63 (Nov 2013) ISSN: 1460-2407 [Electronic] England
PMID23804707 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References
  • Antigens
  • Biomarkers
  • PAPPA2 protein, human
  • Pregnancy-Associated Plasma Protein-A
  • Animals
  • Antigens (blood)
  • Biomarkers (blood)
  • Female
  • Fetal Diseases (blood, diagnosis)
  • HEK293 Cells
  • Humans
  • Immunoassay (methods)
  • Mice
  • Mice, Knockout
  • Pre-Eclampsia (blood, diagnosis)
  • Pregnancy (blood)
  • Pregnancy-Associated Plasma Protein-A (analysis)
  • Prenatal Diagnosis (methods, standards)
  • Reference Values
  • Sensitivity and Specificity

Join CureHunter, for free Research Interface BASIC access!

Take advantage of free CureHunter research engine access to explore the best drug and treatment options for any disease. Find out why thousands of doctors, pharma researchers and patient activists around the world use CureHunter every day.
Realize the full power of the drug-disease research network!

Choose Username:
Verify Password: