title: Progesterone induced blocking factor seen in pregnancy lymphocytes soon after implantation.
abstract: OBJECTIVE
  The immunomodulatory effect of progesterone (P) in pregnancy manifested via a protein named the P-induced blocking factor (PIBF) was previously reported. The goal of this study was to measure and compare the PIBF expression on lymphocytes between pregnant and non-pregnant women especially in early pregnancy.
  
  
  METHODS
  PIBF expression was determined by immunocytochemistry using a PIBF-specific polyclonal antibody. Levels were assessed during the mid-cycle, luteal phase, and first trimester of pregnancy.
  
  
  RESULTS
  PIBF expression was found in 24.9% of mid-cycle sera, 49% of luteal phase sera of women who failed to conceive, and 75% of luteal phase sera of women who conceived.
  
  
  CONCLUSIONS
  These data indicate that the percentage of PIBF expressing lymphocytes increases as a result of pregnancy and that the stimulus for PIBF induction occurs soon after implantation. These data support the concept that PIBF may play an important role in early implantation possibly by inhibiting the destructive function of natural killer lymphocytes.
authors.affiliation: University of Medicine and Dentistry of New Jersey, Robert Wood Johnson University Medical Center, Department of Obstetrics and Gynecology, Camden, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Check
authors.forename: J
authors.initials: J
authors.lastname: Szekeres-Bartho
authors.forename: A
authors.initials: A
authors.lastname: O'Shaughnessy
mesh_terms: D000951:Antigens, Neoplasm / Q000032:analysis / Q000096:biosynthesis*; D010064:Embryo Implantation / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism*; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000096:biosynthesis*; D011374:Progesterone / Q000494:pharmacology*; D013491:Suppressor Factors, Immunologic
chemical_list: D000951:Antigens, Neoplasm; C110058:PIBF1 protein, human; D011257:Pregnancy Proteins; D013491:Suppressor Factors, Immunologic; C020163:blocking factor; D011374:Progesterone