Abstract
A direct, solid-phase time-resolved fluoroimmunoassay (TRFIA) for measuring 17α-hydroxyprogesterone (17-OHP) in dried blood spotted on filter paper is described. The assay is based on competition between europium (Eu)-la beled 17- OHP and free 17-OHP in blood specimens for polyclonal rabbit anti-17-OHP antibodies. The antibody-label complex is separated by binding to anti-rabbit antibodies coated onto microtiter plate wells. The amount of bound Eu-labeled 17- OHP is inversely proportional to the amount of 17-OHP in the sample. After separation of bound and free fractions, the fluorescence intensity of Eu is measured by TRFIA. 17-OHP values obtained by this method correlated well with those obtained by enzyme linked immunosorbent assay (ELISA) (r=0.969). The detection limit of 17-OHP was 1pg/ assay, being almost equivalent to those of the chemiluminescent and fluorescent enzyme immunoassays developed previously.
