• Immunomodulatory protein;
  • IVF;
  • leukocyte immunization;
  • NK cells;
  • progesterone receptor;
  • spontaneous abortion

PROBLEM: To determine if allogenic stimulation from leukocyte immunization (LI) can increase the production of an immunomodulatory protein called progesterone induced blocking factor (PIBF) by CD8+ T-lymphocytes.

METHOD: The study group consisted of 35 women, 29 who failed to conceive after repeated embryo transfers (ETs) and six with recurrent spontaneous abortion (RSA). The women underwent LI using the male partner's blood as the source of leukocytes. Progesterone induced blocking factor was measured pre- and post-LI with an immunocytochemistry method using a PIBF-specific polyclonal antibody.

RESULTS: The mean percentage of lymphocytes expressing PIBF, as well as the percentage of cases whose PIBF level increased to 1% or more, was significantly higher post-LI. Similarly post-LI, there was a significantly lower percentage of zero PIBF levels.

CONCLUSIONS: Leukocyte immunization causes an increase in PIBF in many cases. Possibly the improved pregnancy outcome in immunized patients with RSA or previous failure to conceive with in vitro fertilization may be partially or possibly completely explained by its stimulatory effect on PIBF.