Radioimmunoassay for a progestagen-associated protein of the human endometrium.

Abstract

We have previously demonstrated the presence of a progestagen-associated endometrial protein (PEP) in women. In this communication, we report the development of a RIA for PEP. We describe the use of this method for determining changes in PEP concentration that occur in the endometrium, amniotic fluid, and serum during the normal menstrual cycle and pregnancy. This assay used a partially purified PEP as the reference standard, purified radioiodinated PEP as the tracer, and a goat antibody to PEP as the specific antibody. The assay appears to be highly specific, since the tracer did not bind to antibodies to several known pregnancy-associated plasma, uterine, or placental proteins, including human transferrin, α1-anti-trypsin, ceruloplasmin, human PRL, placental protein SP1, pregnancy zone protein, α-fetoprotein, hCG, pregnancy-associated plasma proteins, and rabbit uteroglobin. Also, hCG, human PRL, and rabbit uteroglobin did not compete for the binding of the tracer to anti-PEP. The detection threshold of...