engleski

Mutual cytotoxic reactions between decidual NK and dendritic cells

The aim of this study was to investigate possible mutual cytotoxic reactions and mechanisms employed by decidual DC and CD56+ cells. Decidual mononuclear cells (DMC), obtained from early human pregnancy decidua after enzymatic digestion and gradient centrifugation were cultured overnight at 37oC. Non adherent DMC fraction was used for positive magnetic separation of CD56+ cells and enrichment of CD83+ cells from "CD56 negative" fraction. Decidual CD1a+ cells were separated from decidual adherent cells. The expression of cytotoxicity receptors were performed in CD56+ cells and CD1a+CD56- cells by flow cytometry. Perforin, granulysin, Fas ligand (FasL), tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and serine asterases were investigated by RT-PCR, flow cytometry and/or confocal microscopy in decidual NK or DC, respectively. Cytotoxicity of NK cells against DC and vice versa were measured by 2-hours PKH-26 cytotoxicity assay. In some assays monoclonal antibodies (mAb) toward cytolytic molecules, NK cell receptors or MHC class I chain related – A/B (MIC A/B) antigen were used, respectively. CD1a+ cells from freshly isolated DMC suspensions express pro-inflammatory cytokines  IL-15 and IL-18 (30-45%), IFN- (~15%) and TNF- (~6%) , cytolytic mediators (perforin, granulysin, FasL and TAIL) and CD94, NKG2D in higher percentage. These cells were able to kill cognate decidual NK cells from 5-15% (effector:target ratios 6:1 - 25:1) by perforin mechanism. Decidual CD56+ cells, riched in cytolytic granules, kill significantly less CD1a+ cells in comparison to CD83+ cells, although perforin caused both lyses. Additional effects of anti-FasL, anti-TRAIL and anti-granulysin mAb were observed neither in DC nor in CD56+ cells killing. NKG2D is expressed on positively selected CD56+ cells, but decidual DC are devoid of MIC A/B, that way anti-NKG2D and anti-MIC A/B mAb did not affect killing of DC. Anti-NKp46 mAb completely abrogated NK cell killing of CD1a+ cells, but not those of CD83+ cells, thus the effects of anti-NKp44 oe anti-NKp30 was not observed. Decidual CD1a+ cells are able to produce pro-inflammatory cytokines, cytolytic mediators and show selective cytotoxicity against cognate NK cells. CD1a+ cells are somehow protected more than CD83+ cells from NK cell mediated lysis, although CD1a+ DC are able to bind for NKp46 receptor on decidual NK cells providing that way activating signal in NK cells for their own lyses. Perforin seems to be main cytolytic mediator imployed in regulation of leukocyte subpopulations at the maternal-fetal interface.

decidual NK cells; dendritic cells; pregnancy

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