• Immunomodulatory protein;
  • implantation;
  • luteal phase

PROBLEM: To compare the expression by T-lymphocytes of an immunomodulatory protein known as progesterone-induced blocking factor (PIBF) in conception versus non-conception cycles even when there has been definite fertilization and embryo formation.

METHOD: PIBF expression on T lymphocytes was measured using an immunohistochemical method with a PIBF-specific polyclonal antibody. These levels were determined in patients 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 PIBF and beta human chorionic gonadotropin. Comparison of the frequency of lymphocyte expression of PIBF in pregnant versus non-pregnant women 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.

CONCLUSION: These data are consistent with the hypothesis that maternal expression of PIBF in T-lymphocytes soon after trophoblast invasion may depend on successful implantation.