The unique receptor repertoire of dNK cells further includes the expression of several Ly49 receptors, the expression of activation markers such as CD69 and KLRG1 (which is considered as a marker for active NK cell proliferation37) and the expression of CD117 (the c-kit receptor). Another study, by Mallidi et al.17 described the phenotype of NK1.1+ dNK cells as DX5+ NKp46+ CD27+ CD11b+ CD11c+ CD69+. Interestingly, the NK1.1+ dNK cells expressed more B220 and CD69 than NK1.1+ eNK cells and also expressed ICOS (which is expressed on activated NK cells38), whereas eNK cells did not express ICOS at all. In the fetal-maternal interface, the maternal uterine tissue is
in close contact with the fetal-derived trophoblast cells. This interface contains immune cells, which constitute selleck monoclonal humanized antibody 40% of the cells in the human decidua.39 Analysis of this immune population has revealed that, unlike any other tissues or mucosal surfaces, 50–70% of the human decidual lymphocytes are NK cells, while the remainder are CD14+ macrophages, dendritic cells,
CD4+ T cells, a few CD8+ T cells, γδ T cells, and NKT cells.35 dNK cell numbers are the highest in the first trimester of pregnancy and their numbers decline during the second trimester. As in mice, only few dNK cells are present in the human decidua at term.36 The majority of dNK cells are CD56bright CD16− (as opposed to mouse dNK cells which express high levels of CD1618). Indeed, dNK cells BI 6727 molecular weight resemble peripheral blood CD56bright CD16− NK cells also in the high expression levels of CD94/NKG2.40 However, similar to eNK cells, dNK cells resemble CD56dim CD16+ NK cells in the expression of KIRs41 and in their granules cell content. In fact, dNK cells differ from peripheral Buspirone HCl blood NK cells both in phenotype and in function. Comparison analysis of the gene expression in dNK cells versus peripheral blood NK cells showed that dNK cells
should be considered as a unique NK subset.27 dNK cells over-expressed several genes, compared with the two peripheral blood NK subsets and several genes were exclusively expressed in dNK cells. For example, granzyme A was significantly over-expressed in dNK cells, as were the C-type lectin-like receptors NKG2C and NKG2E. dNK cells have been shown to express several activating receptors, including NKp46, NKp30, NKp44 (in contrast to human eNK cells which lack NKp30 and NKp44 expression, as discussed above), NKG2D, and 2B4.42–44 The expression of NKp44 (which is not expressed on non-activated peripheral blood NK cells) and the expression of the activation marker CD6945 (which is also expressed on mouse dNK cells) suggest that dNK cells might already be activated in the local environment of the decidua.