MiRNA-mediated control of HLA-G expression and function.

HLA-G is a non-classical HLA class-Ib molecule expressed mainly by the extravillous cytotrophoblasts (EVT) of the placenta. The expression of HLA-G on these fetal cells protects the EVT cells from immune rejection and is therefore important for a healthy pregnancy. The mechanisms controlling HLA-G expression are largely unknown.

The unique properties of uterine NK cells.

Natural killer (NK) cells are lymphocytes of the innate immunity system that are able to kill various hazardous pathogens and tumors. However, it is now widely accepted that NK cells also possess non-destructive functions, as has been demonstrated for uterine NK cells. Here, we review the unique properties of the NK cells in the uterine mucosa, prior to and during pregnancy.

Notch activation enhances IFNgamma secretion by human peripheral blood and decidual NK cells.

NK cells specialize in killing tumor cells and virally infected cells and also possess non-cytotoxic functions, which include secretion of a variety of cytokines and growth factors. Their activity is mediated by a vast repertoire of inhibitory and activating NK receptors. Recently, it was demonstrated that ligation of the Notch receptor plays a significant role not only in T cell development but also in human T cell and mouse NK cell activation.

Endometrial NK cells are special immature cells that await pregnancy.

NK cells populate the human endometrium before pregnancy. Unlike decidual NK cells that populate the decidua during pregnancy, the NK cells present in the human endometrium, before pregnancy, have not been fully characterized. In this study, we provide a detailed analysis of the origin, phenotype, and function of endometrial NK cells (eNK).

Influenza virus infection augments NK cell inhibition through reorganization of major histocompatibility complex class I proteins.

The killing by natural killer (NK) cells is regulated by inhibitory, costimulatory, and activating receptors. The inhibitory receptors recognize mainly major histocompatibility complex (MHC) class I molecules, while the activating NK receptors recognize stress-induced ligands and viral products. Thus, changes in the expression of the various inhibitory and activating ligands will determine whether target cells will be killed or protected.

Intracellular cysteine residues in the tail of MHC class I proteins are crucial for extracellular recognition by leukocyte Ig-like receptor 1.

The activity of NK cells is regulated by activating receptors that recognize mainly stress-induced ligands and by inhibitory receptors that recognize mostly MHC class I proteins on target cells. Comparing the cytoplasmic tail sequences of various MHC class I proteins revealed the presence of unique cysteine residues in some of the MHC class I molecules which are absent in others. To study the role of these unique cysteines, we performed site specific mutagenesis, generating MHC class I molecules lacking these cysteines, and demonstrated that their expression on the cell surface was impaired.

Decidual NK cells regulate key developmental processes at the human fetal-maternal interface.

Human CD56(bright) NK cells accumulate in the maternal decidua during pregnancy and are found in direct contact with fetal trophoblasts. Several mechanisms have been proposed to explain the inability of NK cells to kill the semiallogeneic fetal cells. However, the actual functions of decidual NK (dNK) cells during pregnancy are mostly unknown.