title: Human trophoblast cells express the immunomodulator progesterone-induced blocking factor.
abstract: Progesterone-induced blocking factor (PIBF) is an immunomoduatory factor with anti-abortive properties. In this study, we present evidence that PIBF is synthesized in the human placenta and determine its cellular source. Expression of PIBF was analysed with polyclonal rabbit anti-human PIBF antibodies against recombinant N-terminal 48kDa PIBF in first trimester and term placental tissues and in the choriocarcinoma cell line JAR by means of immunohistochemistry, confocal laser scanning microscopy of double immunofluorescence labelling, and Western blotting; RT-PCR was performed for analysis of PIBF mRNA in isolated trophoblast cells. PIBF protein is present in human first trimester and term placenta. Double immunofluorescence labelling localised PIBF to the extravillous cytotrophoblast. PIBF is also expressed heterogeneously by syncytiotrophoblast and part of the villous cytotrophoblast. Full-length PIBF mRNA encoded by exons 1-18 is present in isolated first trimester and term villous trophoblast and in the choriocarcinoma cell line JAR. The corresponding 90kDa protein is expressed by JAR cells, first trimester and term villous trophoblast cells. In addition, these cells express PIBF proteins of 50 and 34kDa. Trophoblast is a source of PIBF; its tissue distribution suggests a role both in systemic and local (decidual) immunoregulation.
authors.affiliation: Institute of Cell Biology, Histology and Embryology, Medical University of Graz, A-8010 Graz, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Anderle
authors.forename: A
authors.initials: A
authors.lastname: Hammer
authors.forename: B
authors.initials: B
authors.lastname: Polgár
authors.forename: M
authors.initials: M
authors.lastname: Hartmann
authors.forename: R
authors.initials: R
authors.lastname: Wintersteiger
authors.forename: A
authors.initials: A
authors.lastname: Blaschitz
authors.forename: G
authors.initials: G
authors.lastname: Dohr
authors.forename: G
authors.initials: G
authors.lastname: Desoye
authors.forename: J
authors.initials: J
authors.lastname: Szekeres-Barthó
authors.forename: P
authors.initials: P
authors.lastname: Sedlmayr
mesh_terms: D019002:CD56 Antigen / Q000032:analysis; D045744:Cell Line, Tumor; D002823:Chorion / Q000737:chemistry; D003656:Decidua / Q000737:chemistry; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000032:analysis* / Q000235:genetics / Q000652:urine; D012333:RNA, Messenger / Q000032:analysis; D013491:Suppressor Factors, Immunologic / Q000032:analysis* / Q000235:genetics / Q000652:urine; D014327:Trophoblasts / Q000737:chemistry / Q000276:immunology*
chemical_list: D019002:CD56 Antigen; C110058:PIBF1 protein, human; D011257:Pregnancy Proteins; D012333:RNA, Messenger; D013491:Suppressor Factors, Immunologic