NK Cells and Other Innate Lymphoid Cells in Hematopoietic Stem Cell Transplantation.

Natural killer (NK) cells play a major role in the T-cell depleted haploidentical hematopoietic stem cell transplantation (haplo-HSCT) to cure high-risk leukemias. NK cells belong to the expanding family of innate lymphoid cells (ILCs). At variance with NK cells, the other ILC populations (ILC1/2/3) are non-cytolytic, while they secrete different patterns of cytokines.

MSC and innate immune cell interactions: A lesson from human decidua.

Both experimental and clinical studies revealed that stromal cells (SC) are present in decidua (DSC) and placenta (PSC) at the early and late phase of pregnancy, respectively, and they may contribute to the induction of an anti-inflammatory/tolerogenic microenvironment crucial for the establishment/maintenance of successful pregnancy. These cells share common features with mesenchymal SC. In the present contribution, we provide an overall view on DSC features and on their ability to recruit NK cells and to regulate both differentiation and function not only of NK cells but also of CD14(+) myeloid cells.

Unique Eomes(+) NK Cell Subsets Are Present in Uterus and Decidua During Early Pregnancy.

Decidual and uterine natural killer (NK) cells have been shown to contribute to the successful pregnancy both in humans and mice. NK cells represent "cytotoxic" group 1 innate lymphoid cells (ILCs) and are distinct from the recently described "helper" ILC1. Here, we show that both in humans and mice the majority of group 1 ILC in endometrium/uterus and decidua express Eomesodermin (Eomes), thus suggesting that they are developmentally related to conventional NK cells.

Stromal cells from human decidua exert a strong inhibitory effect on NK cell function and dendritic cell differentiation.

Stromal cells (SC) are an important component of decidual tissues where they are in strict proximity with both NK and CD14(+) myelomonocytic cells that play a role in the maintenance of pregnancy. In this study we analyzed whether decidual SC (DSC) could exert a regulatory role on NK and CD14(+) cells that migrate from peripheral blood (PB) to decidua during pregnancy. We show that DSCs inhibit the IL15-mediated up-regulation of major activating NK receptors in PB-derived NK cells.

In vivo generation of decidual natural killer cells from resident hematopoietic progenitors.

Decidual natural killer cells accumulate at the fetal-maternal interface and play a key role in a successful pregnancy. However, their origin is still unknown. Do they derive from peripheral natural killer cells recruited in decidua or do they represent a distinct population that originates in situ? Here, we identified natural killer precursors in decidua and uterus of pregnant mice.