Human decidual stromal cells express HLA-G: Effects of cytokines and decidualization

BACKGROUND: Decidual stromal cells (DSC) are the main cellular componentof the decidua, the maternal tissue in close contact with fetaltrophoblast. Although of mesenchymal origin, DSC exert numerousimmune functions that seem to be relevant for the immunologicalrelationship between the mother and fetus. HLA-G, an antigenpreferentially expressed by trophoblast, appears to participatein the immune tolerance by the mother of the semiallogeneicfetus. METHODS AND RESULTS: We show by flow cytometry, fluorescence microscopy, westernblotting and RT–PCR that DSC isolated and maintained inculture express HLA-G weakly but consistently. We also detectedthis antigen by flow cytometry in fresh DSC. Interleukin (IL)-10,a cytokine associated with normal pregnancy, increased the expressionof HLA-G by DSC (P < 0.00001), whereas IL-2, a cytokine involvedin spontaneous abortion, showed no effect. Decidualization byprogesterone and cAMP also up-regulated the expression of HLA-Gby DSC (P < 0.001). Interferon , a cytokine implicated inthe vascular remodelling of the decidua necessary for embryoimplantation, also increased the expression of HLA-G by DSC(P < 0.05). CONCLUSIONS: Our results suggest the existence of a network in which hormonestogether with cytokines regulate the expression of HLA-G byDSC, and that may be of relevance in the maintenance of maternal–fetaltolerance.