title: Cytotoxic potential of decidual NK cells and CD8+ T cells awakened by infections.
abstract: To establish a healthy pregnancy the maternal immune system must tolerate fetal allo-antigens, yet remain competent to respond to infections. The ability of decidual NK cells (dNK) to promote migration of fetal extravillous trophoblasts (EVT) and placental growth as well as the capacity of EVT to promote immune tolerance are topics of high interest and extensive research. However, the problem of how dNK and decidual CD8+ T cells (CD8+ dT) provide immunity to infections of the placenta and the mechanisms that regulate their cytolytic function has thus far largely been ignored. Fetal EVT are the most invasive cells of the placenta and directly interact with maternal decidual immune cells at this maternal-fetal interface. Besides the expression of non-polymorphic HLA-E and HLA-G molecules that are associated with immune tolerance, EVT also express highly polymorphic HLA-C molecules that can serve as targets for maternal dNK and CD8+ dT responses. HLA-C expression by EVT has a dual role as the main molecule to which immune tolerance needs to be established and as the only molecule that can present pathogen-derived peptides and provide protective immunity when EVT are infected. The focus of this review is to address the regulation of cytotoxicity of dNK and CD8+ dT, which is essential for maternal-fetal immune tolerance as well as recent evidence that both cell types can provide immunity to infections at the maternal-fetal interface. A particular emphasis is given to the role of HLA-C expressed by EVT and its capacity to elicit dNK and CD8+ dT responses.
authors: Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA; PhD Program in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.
authors: Ângela C
authors: ÂC
authors: Crespo
authors: Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA; Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, Netherlands.
authors: Anita
authors: A
authors: van der Zwan
authors: Center for Neuroscience and Cell Biology and Department of Life Sciences, University of Coimbra, Portugal.
authors: João
authors: J
authors: Ramalho-Santos
authors: Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA.
authors: Jack L
authors: JL
authors: Strominger
authors: Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA. Electronic address: tilburgs@fas.harvard.edu.
authors: Tamara
authors: T
authors: Tilburgs
mesh_terms: D056704:Adaptive Immunity; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D003656:Decidua / Q000276:immunology*; D005260:Female; D015236:HLA-C Antigens / Q000378:metabolism; D006801:Humans; D007108:Immune Tolerance; D007113:Immunity, Innate; D007112:Immunity, Maternally-Acquired; D007239:Infections / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D021041:Placental Circulation; D011247:Pregnancy; D014327:Trophoblasts / Q000276:immunology*
chemical_list: D015236:HLA-C Antigens
keywords: EVT; HCMV; Human; Perforin; Pregnancy