Post transplant infusion of donor-type natural killer (NK) cells has been shown to have an anti-leukemia-enhancing effect without evoking GVHD in murine hematopoietic cell transplantation (HCT) models. Here, we tested 14 patients (age, 23-65 years), 12 with acute leukemia and 2 with myelodysplastic syndrome, who underwent HLAmismatched HCT and subsequently received donor NK cell infusions. Cell donors (age, 16-51 years), comprising seven siblings, five offspring, and two mothers of the patients, underwent growth factor-mobilized leukapheresis for 3-5 days. Cells collected on the first 2-4 days were used for HCT, whereas those collected on the last day were CD34 selected by magnetic-activated cell sorting (median, 2.22 Â 10 6 cells/kg; range, 0.29-5.66). Donor NK cells were generated from the CD34 þ cells by ex vivo cell culture over a 6-week period (median, 9.28 Â 10 6 cells/ kg; range, 0.33-24.50; CD122/CD56 þ 64%; CD3 þ 1.0%; and viability 88%). There were no signs of acute toxicity in patients infused with these cells 6-7 weeks post transplant. Overall, one and five patients developed acute and chronic GVHD during post transplant period, respectively. These results showed that clinical-grade donor NK cell production from CD34 þ cells is feasible.

Natural killer (NK) cells play important roles in immune surveillance. However, the tumor microenvironment suppresses NK cell function and allows cancer cells to evade immune detection. In this study, we investigated whether the thyroid cancer cell microenvironment has this effect on NK cells. We found that prostaglandin (PG) E2 produced by thyroid cancer cells suppressed the cytolytic activity of NK cells by inhibiting the expression of the natural cytotoxicity receptors NKp44 and NKp30 and the death receptor tumor necrosis factor-related apoptosis-inducing ligand. PGE2 and cyclooxygenase-2 were highly expressed in thyroid cancer cells; moreover, anaplastic thyroid cancer cells released higher amounts of PGE2 than the papillary subtype, which was associated with suppression of NK cell-inducing nuclear factor-κB and mitogen-activated protein kinase/extracellular signal-regulated kinase pathways via PGE2 receptor (EP) 2 and EP4 expressed on the NK cell surface. In addition, PGE2 inhibited the functional maturation of NK cells and reduced their cytotoxicity against target cells. These results indicate that PGE2 promotes thyroid cancer progression by inhibiting NK cell maturation and cytotoxicity. Thus, therapeutic strategies that target PGE2 in thyroid cancer could potentiate the immune response and improve patient prognosis.

The doses of donor-derived natural killer (NK) cells that can be given safely after human leukocyte antigen (HLA)-haploidentical hematopoietic cell transplantation (HCT) remain to be defined. Forty-one patients (ages 17 to 75 years) with hematologic malignancy underwent HLA-haploidentical HCT after reduced-intensity conditioning containing busulfan, fludarabine, and antithymocyte globulin. Cell donors (ages 7 to 62 years) underwent growth factor-mobilized leukapheresis for 3 to 4 days. Cells collected on the first 2 to 3 days were used for HCT, whereas those collected on the last day were CD3-depleted and cultured into NK cells using human interleukins-15 and -21. These NK cells were then infused into patients twice at 2 and 3 weeks after HCT at an escalating doses of .2 × 10(8) cells/kg of body weight (3 patients), .5 × 10(8) cells/kg (3 patients), 1.0 × 10(8) cells/kg (8 patients), and ≥ 1.0 × 10(8) cells/kg or available cells (27 patients). At all dose levels, no acute toxicity was observed after NK cell infusion. After HLA-haploidentical HCT and subsequent donor NK cell infusion, when referenced to 31 historical patients who had undergone HLA-haploidentical HCT after the same conditioning regimen but without high-dose NK cell infusion, there was no significant difference in the cumulative incidences of major HCT outcomes, including engraftment (absolute neutrophil count ≥ 500/μL, 85% versus 87%), grade 2 to 4 acute graft-versus-host disease (GVHD, 17% versus 16%), moderate to severe chronic GVHD (15% versus 10%), and transplantation-related mortality (27% versus 19%). There was, however, a significant reduction in leukemia progression (74% to 46%), with post-transplantation NK cell infusion being an independent predictor for less leukemia progression (hazard ratio, .527). Our findings showed that, when given 2 to 3 weeks after HLA-haploidentical HCT, donor-derived NK cells were well tolerated at a median total dose of 2.0 × 10(8) cells/kg. In addition, they may decrease post-transplantation progression of acute leukemia.

NK cells are a key component of innate immune systems, and their activity is regulated by cytokines and hormones. Adiponectin, which is secreted from white adipose tissues, plays important roles in various diseases, including hypertension, cardiovascular diseases, inflammatory disorders, and cancer. In this study the effect of adiponectin on NK cell activity was investigated. Adiponectin was found to suppress the IL-2-enhanced cytotoxic activity of NK cells without affecting basal NK cell cytotoxicity and to inhibit IL-2-induced NF-κB activation via activation of the AMP-activated protein kinase, indicating that it suppresses IL-2-enhanced NK cell cytotoxicity through the AMP-activated protein kinase-mediated inhibition of NF-κB activation. IFN-γ enhances NK cell cytotoxicity by causing an increase in the levels of expression of TRAIL and Fas ligand. The production of IFN-γ, one of the NF-κB target genes in NK cells, was also found to be suppressed by adiponectin, accompanied by the subsequent down-regulation of IFN-γ-inducible TRAIL and Fas ligand expression. These results clearly demonstrate that adiponectin is a potent negative regulator of IL-2-induced NK cell activation and thus may act as an in vivo regulator of anti-inflammatory functions.

IntroductionNatural killer (NK) cells play key roles in innate and adaptive immune responses during early host defense against infectious pathogens and tumors via 2 major mechanisms: contact-dependent cytotoxicity and cytokine production for immune modulation. [1][2][3][4] Target-cell death is primarily mediated via the granule-exocytosis pathway. NK cells are armed by functional cytotoxic granules containing perforin (Prf1) and granzymes, essential effector molecules for NK-cell cytotoxicity as shown in knockout mice, 4,5 and are triggered to mediate effector activity by receptor ligation. Prf1 facilitates the delivery of granzymes into the cytosol of the target cell, and GzmB, the best-characterized granzyme, cleaves several procaspases, BID, inhibitor of caspase-activated DNase, and other intracellular substrates to initiate the classic apoptotic pathways. [6][7][8][9] Many of the studies of Prf1 and GzmB expression in NK cells have suggested the possible involvement of posttranscriptional regulation. Recently, studies using murine NK cells have shown that acquisition of murine NK-cell cytotoxicity requires the translation of a pre-existing pool of Prf1 and GzmB mRNAs. 4 Despite high basal levels of Prf1 and GzmB mRNA, little protein expression is observed under resting conditions in many types of NK cells, whereas expression of both proteins is up-regulated during activation. 4,10,11 These observations are consistent with a posttranscriptional mechanism operating to allow NK cells to be poised for but to prevent translation before activation, such as silencing by microRNAs. 12,13 microRNAs are an abundant class of endogenous small noncoding RNAs (19-22 nt) generated by sequential processing of primary miRNA transcripts by the ribonuclease Drosha in the nucleus and Dicer1 in the cytoplasm, both of which are essential enzymes in the miRNA biogenesis pathway. In mammals, mature miRNAs are integrated into an RNA-inducing silencing complex, including Argonaute 2 (Ago2), a required endonuclease in the RNA interference pathway, and they associate with 3Ј untranslated regions (UTRs) of specific target mRNAs to down-regulate gene expression by targeting mRNAs for translational suppression or mRNA degradation. [13][14][15][16][17] The involvement of miRNA in immune responses and the development of immune cells from hematopoietic stem cells have been widely investigated by manipulation of specific miRNA levels 13,18 or by disruption of molecules involved in biogenesis and activity of all miRNAs, such as Arg, 19 Drosha, 20 and Dicer. [21][22][23][24] Recently, characterization of NK cells from mice with conditional deletion of Dicer and DiGeorge syndrome critical region 8 were reported, with evidence of impairments in NK-cell activation, survival, and function during viral infection. 24 These genetic studies have suggested miRNAs play essential roles in immune cell development and function. 13,14,25 Despite evidence for a broad impact in regulation of immune function, the molecular mechanism, importance, and biologic si...