title: Microparticle-free placentally derived soluble factors downmodulate the response of activated T cells.
abstract: Soluble placental factors may have immunoregulatory properties and have been demonstrated to inhibit T-lymphocyte proliferation in vitro. On the other hand, placentally derived syncytiotrophoblast microparticles and crude placental homogenates have been demonstrated to inhibit proliferation of mixed lymphocytes in vitro. Because previous studies on placentally derived soluble factors may have been contaminated by the presence of trophoblast-derived microparticles, we prepared microparticle-free placental supernatants. Such supernatants reduced the activation response of T cells, as well as their proliferation and the production of cytokines such as interleukin-2 and interferon gamma, in a dose-dependent manner. This reduction in T-cell proliferation does not appear to be caused by indoleamine 2,3-dioxygenase (IDO) because it was not reversed by the addition of L-tryptophan or an inhibitor of IDO (1-methyl-DL-tryptophan). No evidence was found for the presence of IDO in these supernatants when we used a biochemical assay measuring tryptophan catabolism. We conclude that the placenta produces currently unknown soluble factors that reduce T-cell activation, proliferation, and cytokine production.
authors.affiliation: Laboratory for Prenatal Medicine, University Women's Hospital/Department of Research, University Hospital, Basel, Switzerland.
authors.forename: Anurag Kumar
authors.initials: AK
authors.lastname: Gupta
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Holzgreve
authors.forename: Sinuhe
authors.initials: S
authors.lastname: Hahn
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism; D017209:Apoptosis; D049109:Cell Proliferation; D002824:Chorionic Villi / Q000276:immunology* / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D007155:Immunologic Factors; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000037:antagonists & inhibitors / Q000378:metabolism; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000276:immunology*; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D016207:Cytokines; D007155:Immunologic Factors; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D037181:Lectins, C-Type; D000099192:CD69 Antigens