title: Expression of CD24 and Siglec-10 in first trimester placenta: implications for immune tolerance at the fetal-maternal interface.
abstract: During pregnancy, the fetal-maternal interface establishes immune tolerance between the fetus and the mother. CD24, a mucin-like glycoprotein expressed at the surface of hematopoietic cells and diverse tumor cells, is known to interact with the sialic acid-binding immunoglobulin-type lectins (Siglecs). This interaction was assessed as a candidate complex for the immune suppression response in the placenta. CD24 was affinity purified from term placenta and characterized by SDS-PAGE, Western blot and ELISA. Binding of recombinant Siglecs to placental CD24 was evaluated by ELISA. The expression of CD24 and Siglec-10 in first trimester placental tissues was investigated by immunohistochemistry and immunofluorescence. Placental CD24 had an apparent molecular weight of 30-70 kDa consistent with its high degree of N- and O-linked glycosylation. EDTA-sensitive CD24-Siglec-10 interaction via the terminal sialic acid glycan residues of CD24 was observed. CD24 did not interact with Siglec-3 or Siglec-5. During the first trimester, and already in gestational week (GA) 8, CD24 showed high expression in villous and extravillous cytotrophoblasts. There was also a mild expression in stromal cells, while syncytiotrophoblasts were negative. Co-localization of CD24 with Siglec-10 was observed in endometrial glands and in first trimester decidual cells in close vicinity to extracellular trophoblasts. This study is the first to demonstrate the early presence of CD24 in the placenta cytotrophoblast layers, placental bed and maternal uterine glands. The presence of the CD24-Siglec-10 in these regions of fetal-maternal interactions suggests a possible role in mediating immune tolerance at the fetal-maternal interface.
authors.affiliation: Prof. Ephraim Katzir Department of Biotechnology Engineering, ORT Braude College, P.O. Box 78, 2161002, Karmiel, Israel. sammar@braude.ac.il.
authors.forename: Marei
authors.initials: M
authors.lastname: Sammar
authors.affiliation: Institute of Cell Biology, Histology and Embryology, Medical University of Graz, 8010, Graz, Austria.
authors.forename: Monika
authors.initials: M
authors.lastname: Siwetz
authors.affiliation: Hy laboratories, Rehovot and TeleMarpe, Tel Aviv, Israel.
authors.forename: Hamutal
authors.initials: H
authors.lastname: Meiri
authors.affiliation: Skin Cancer Unit, DKFZ, Heidelberg, Germany.|Department of Dermatology Venereology and Allergology, University Medical Center Mannheim Ruprecht-Karl University of Heidelberg, Mannheim, Germany.
authors.forename: Viktor
authors.initials: V
authors.lastname: Fleming
authors.affiliation: Skin Cancer Unit, DKFZ, Heidelberg, Germany.|Department of Dermatology Venereology and Allergology, University Medical Center Mannheim Ruprecht-Karl University of Heidelberg, Mannheim, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Altevogt
authors.affiliation: Institute of Cell Biology, Histology and Embryology, Medical University of Graz, 8010, Graz, Austria.
authors.forename: Berthold
authors.initials: B
authors.lastname: Huppertz
mesh_terms: D051927:CD24 Antigen / Q000096:biosynthesis* / Q000276:immunology / Q000302:isolation & purification; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology*; D037102:Lectins / Q000096:biosynthesis* / Q000276:immunology / Q000302:isolation & purification; D008431:Maternal-Fetal Exchange / Q000276:immunology*; D010920:Placenta / Q000276:immunology* / Q000378:metabolism; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000276:immunology* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000276:immunology / Q000302:isolation & purification
chemical_list: D051927:CD24 Antigen; C497889:CD24 protein, human; D037102:Lectins; D011956:Receptors, Cell Surface; C426228:SIGLEC10 protein, human
keywords: CD24; Cytotrophoblast; First trimester; Glycans; Placenta; Siglecs; Syncytiotrophoblast