Direct solid-phase chemiluminescence immunoassay for salivary progesterone

Abstract

A simple, direct chemiluminescence immunoassay for progesterone in mixed, unstimulated saliva is described. We use purified polyclonal anti-progesterone antibodies covalently coupled to polyacrylamide beads and progesterone-11α-hemisuccinyl-aminobutylethyl isoluminol as the chemiluminescent ligand marker. Bound and free ligand are separated by simple centrifugation. The detection limit of the assay is 1.5 pg per tube (38 pmol/L). Intra- and interassay coefficients of variation for low, medium, and high progesterone concentrations are 7.9, 6.8, 8.8% and 9.3, 6.9, 8.5%, respectively. Analytical recovery of added progesterone is 99.6%. Mean ± SD progesterone concentrations (pmol/L) in saliva are 178 ± 46 in the follicular phase, 313 ± 90 in the periovulatory phase, and 658 ± 166 in the luteal phase of the menstrual cycle. Correlation between progesterone concentrations in serum (assayed by RIA after extraction) and in saliva is good (r = 0.88, p <0.001, n = 96). The assay is simple, fast (4 h, including 1.5 h of incubation time), and reliable.