Immunological heterogeneity of pregnancy-associated plasma protein-A (PAPP-A). Effects on the radioimmunoassay of PAPP-A.
Pregnancy-associated plasma protein-A (PAPP-A) is a macromolecular glycoprotein produced by the trophoblast during pregnancy. Because the presence of PAPP-A in non-pregnant females is controversial, we re-evaluated our own radioimmunoassay technique for PAPP-A in the light of new observations about its immunological heterogeneity. Irrespective of the antibody (Geneva anti-PAPP-A or Dako anti-PAPP-A) the use of EDTA pregnancy plasma instead of pregnancy serum as a standard yielded different slopes of the standard curves and estimated significantly different amounts of PAPP-A in test samples. Moreover, highly purified tracers, isolated from maternal EDTA pregnancy plasma or pregnancy serum also produced significantly different results. So that the use of a tracer purified from EDTA plasma and EDTA pregnancy plasma as a standard will yield measurable levels of PAPP-A in non-pregnant female serum whereas the use of a tracer purified from maternal pregnancy serum and maternal pregnancy serum as a standard will not detect PAPP-A in the same samples. We conclude that, irrespective of the antiserum used, but depending on the biological origin of the tracer and the standard, different results will be obtained. PAPP-A is clearly immunologically heterogeneous, and the immunorecognition of PAPP-A will depend on whether or not blood coagulation has taken place.
Bischof
P
P
Department of Obstetrics and Gynaecology, University of Geneva, Switzerland.
Meisser
A
A
D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000276:immunology*; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis / Q000276:immunology*; D011863:Radioimmunoassay
D011257:Pregnancy Proteins; D011266:Pregnancy-Associated Plasma Protein-A