EVIDENCE THAT THE EXPRESSION OF PROGESTERONE-INDUCED BLOCKING FACTOR BY MATERNAL T-LYMPHOCYTES IS POSITIVELY CORRELATED WITH CONCEPTION

PROBLEM: To compare the expression by T-lymphocytes of an immunomodula tory protein known as progesterone-induced blocking factor (PIBF) in c onception versus non-conception cycles even when there has been defini te fertilization and embryo formation. METHOD: PIBF expression on T ly mphocytes was measured using an immunohistochemical method with a PIBF -specific polyclonal antibody. These levels were determined in patient s undergoing three types of therapy: non-in vitro fertilization (IVF), IVF-embryo transfer (ET), and frozen ET. Sera were drawn 12 days from ovulation in non-IVF cycles or 9 days after ET and were assayed for P IBF and beta human chorionic gonadotropin. Comparison of the frequency of lymphocyte expression of PIBF in pregnant versus non-pregnant wome n were made. RESULTS: PIBF was detected in 29.5% of non-pregnant women and 52.5% of pregnant women. There were no differences in PIBF levels by therapy used in non-pregnant cases or in the pregnant group. CONCL USION: These data are consistent with the hypothesis that maternal exp ression of PIBF in T-lymphocytes soon after trophoblast invasion may d epend on successful implantation.