Document Detail

Suppression of allogeneic reactivity in vitro by the syncytiotrophoblast membrane glycocalyx of the human term placenta is carbohydrate dependent.
MedLine Citation:
PMID:  8186548     Owner:  NLM     Status:  MEDLINE    
Immunosuppressive factors isolated from trophoblast are known to block both innate and major histocompatibility complex (MHC)-dependent cell-mediated immune responses in vitro and, in some cases, in vivo. We investigated the biochemical nature of these factors, which is presently unknown. Immunosuppressive activity, assessed by inhibition of two-way MLR, was extracted from term syncytiotrophoblast microvilli using 3 M KCl. The activity resisted both extensive pronase digestion and heating to 90 degrees C for 1 h, demonstrating that intact membrane proteins were not required. Although purified protein-linked oligosaccharides released by hydrazinolysis from the syncytiotrophoblast membrane were themselves inactive, they blocked the immunosuppressive activity of the KCl extract. After pronase digestion, the activity could be fractionated by TSK 55S gel filtration, followed by C18 reverse-phase chromatography. Sequential exoglycosidase digestion of hydrazine-released sugars of the active fraction demonstrated that it contained neutral N-linked oligomannose and hybrid oligosaccharides, which normally make up < 3% of the total syncytiotrophoblast-derived protein glycan library. These glycopeptides of the active fraction were associated with membrane phospholipid micelles. The possible mechanism by which incompletely processed N-linked oligosaccharides expressed by a variety of syncytiotrophoblast membrane glycoproteins may block allogeneic reactivity when presented as polyvalent sugar groups is discussed.
P D Arkwright; T W Rademacher; F Boutignon; R A Dwek; C W Redman
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Glycobiology     Volume:  4     ISSN:  0959-6658     ISO Abbreviation:  Glycobiology     Publication Date:  1994 Feb 
Date Detail:
Created Date:  1994-06-23     Completed Date:  1994-06-23     Revised Date:  2009-09-29    
Medline Journal Info:
Nlm Unique ID:  9104124     Medline TA:  Glycobiology     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  39-47     Citation Subset:  IM    
Department of Biochemistry, University of Oxford, UK.
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MeSH Terms
Carbohydrate Metabolism
Carbohydrates / immunology*
Cell Division
Glycoproteins / immunology*,  metabolism
Immune Tolerance / physiology*
Leukocytes, Mononuclear / cytology
Membrane Glycoproteins / immunology*,  metabolism
Membrane Lipids / immunology
Microvilli / immunology,  metabolism
Polysaccharides / immunology*,  metabolism
Trophoblasts / immunology*,  metabolism
Grant Support
//Wellcome Trust
Reg. No./Substance:
0/Carbohydrates; 0/Glycoproteins; 0/Membrane Glycoproteins; 0/Membrane Lipids; 0/Polysaccharides; EC 3.4.24.-/Pronase

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