scholarly journals Loss of kindlin-3 alters the threshold for NK cell activation in human leukocyte adhesion deficiency-III

Blood ◽  
2012 ◽  
Vol 120 (19) ◽  
pp. 3915-3924 ◽  
Author(s):  
Raizy Gruda ◽  
Alice C. N. Brown ◽  
Valentin Grabovsky ◽  
Saar Mizrahi ◽  
Chamutal Gur ◽  
...  
Keyword(s):  
Cell Activation ◽  
Nk Cell ◽  
Leukocyte Adhesion ◽  
Cell Activity ◽  
Human Leukocyte ◽  
Target Cells ◽  
Leukocyte Adhesion Deficiency ◽  
Nk Cell Activity ◽  
Activating Receptors ◽  
Multiple Receptors

Abstract Recent evidence suggests that kindlin-3 is a major coactivator, required for most, if not all, integrin activities. Here we studied the function of kindlin-3 in regulating NK cell activation by studying a patient with kindlin-3 deficiency (leukocyte adhesion deficiency-III). We found that kindlin-3 is required for NK cell migration and adhesion under shear force. Surprisingly, we also found that kindlin-3 lowers the threshold for NK cell activation. Loss of kindlin-3 has a pronounced effect on NK cell–mediated cytotoxicity triggered by single activating receptors. In contrast, for activation through multiple receptors, kindlin-3 deficiency is overcome and target cells killed. The realization that NK cell activity is impaired, but not absent in leukocyte adhesion deficiency, may lead to the development of more efficient therapy for this rare disease.

scholarly journals Nonameric Peptide Orchestrates Signal Transduction in the Activating HLA-E/NKG2C/CD94 Immune Complex as Revealed by All-Atom Simulations

2021 ◽  
Vol 22 (13) ◽  
pp. 6670
Author(s):  
Eva Prašnikar ◽  
Andrej Perdih ◽  
Jure Borišek
Keyword(s):  
Signal Transduction ◽  
Cell Activation ◽  
Nk Cell ◽  
Innate Immune ◽  
Target Cells ◽  
Molecular Events ◽  
Activating Receptors ◽  
Molecular Machinery ◽  
Infected Cells ◽  
Bond Network

The innate immune system’s natural killer (NK) cells exert their cytolytic function against a variety of pathological challenges, including tumors and virally infected cells. Their activation depends on net signaling mediated via inhibitory and activating receptors that interact with specific ligands displayed on the surfaces of target cells. The CD94/NKG2C heterodimer is one of the NK activating receptors and performs its function by interacting with the trimeric ligand comprised of the HLA-E/β2m/nonameric peptide complex. Here, simulations of the all-atom multi-microsecond molecular dynamics in five immune complexes provide atomistic insights into the receptor–ligand molecular recognition, as well as the molecular events that facilitate the NK cell activation. We identify NKG2C, the HLA-Eα2 domain, and the nonameric peptide as the key elements involved in the molecular machinery of signal transduction via an intertwined hydrogen bond network. Overall, the study addresses the complex intricacies that are necessary to understand the mechanisms of the innate immune system.

scholarly journals miR-1224 contributes to ischemic stroke-mediated natural killer cell dysfunction by targeting Sp1 signaling

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Yan Feng ◽  
Yan Li ◽  
Ying Zhang ◽  
Bo-Hao Zhang ◽  
Hui Zhao ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Nk Cells ◽  
Natural Killer ◽  
Brain Ischemia ◽  
Cell Activation ◽  
Nk Cell ◽  
Cell Activity ◽  
Passive Transfer ◽  
Immune Defense ◽  
Nk Cell Activity

Abstract Background Brain ischemia compromises natural killer (NK) cell-mediated immune defenses by acting on neurogenic and intracellular pathways. Less is known about the posttranscriptional mechanisms that regulate NK cell activation and cytotoxicity after ischemic stroke. Methods Using a NanoString nCounter® miRNA array panel, we explored the microRNA (miRNA) profile of splenic NK cells in mice subjected to middle cerebral artery occlusion. Differential gene expression and function/pathway analysis were applied to investigate the main functions of predicted miRNA target genes. miR-1224 inhibitor/mimics transfection and passive transfer of NK cells were performed to confirm the impact of miR-1224 in NK cells after brain ischemia. Results We observed striking dysregulation of several miRNAs in response to ischemia. Among those miRNAs, miR-1224 markedly increased 3 days after ischemic stroke. Transfection of miR-1224 mimics into NK cells resulted in suppression of NK cell activity, while an miR-1224 inhibitor enhanced NK cell activity and cytotoxicity, especially in the periphery. Passive transfer of NK cells treated with an miR-1224 inhibitor prevented the accumulation of a bacterial burden in the lungs after ischemic stroke, suggesting an enhanced immune defense of NK cells. The transcription factor Sp1, which controls cytokine/chemokine release by NK cells at the transcriptional level, is a predicted target of miR-1224. The inhibitory effect of miR-1224 on NK cell activity was blocked in Sp1 knockout mice. Conclusions These findings indicate that miR-1224 may serve as a negative regulator of NK cell activation in an Sp1-dependent manner; this mechanism may be a novel target to prevent poststroke infection specifically in the periphery and preserve immune defense in the brain.

Thermal stresses reduce natural killer cell cytotoxicity

1995 ◽  
Vol 79 (3) ◽  
pp. 732-737 ◽  
Author(s):  
S. J. Won ◽  
M. T. Lin
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Target Cell ◽  
Nk Cell ◽  
Cell Activity ◽  
Cortisol Concentration ◽  
Target Cells ◽  
Nk Cell Activity ◽  
Colonic Temperature ◽  
Effector Target

The effects of different ambient temperatures (Ta) on the splenic natural killer (NK) cell activity, effector-target cell conjugation activity, and NK cell numbers were assessed in male inbred C3H/HeNCrj mice (7–10 wk old). The splenic NK cytotoxic activities were examined in a 4-h 51Cr release assay in mouse spleen cells that were obtained 1, 2, 4, 8, or 16 days after exposure to Ta of 22, 4, or 35 degrees C. The percentage of conjugating lymphocytes was calculated by counting the number of single lymphocytes bound to single target cells per 400 effector cells. The numbers of NK cells were expressed by the percentage of 5E6-positive cells. The 5E6 identifies only a subset of NK cells. It was found that the splenic NK cell activity, the effector-target cell conjugation activity, or the NK cell number began to fall 1 day after cold (Ta 4 degrees C) or heat (Ta 35 degrees C) stress. After a 16-day period of either cold or heat exposure, the fall in the splenic NK cell activity, the effector-target cell conjugation activity, or the number of 5E6-positive subsets of NK cells was still evident. Compared with those of the control group (Ta 22 degrees C), the cold-stressed mice had higher adrenal cortisol concentration and lower colonic temperature, whereas the heat-stressed animals had higher adrenal cortisol concentration and higher colonic temperature during a 16-day period of thermal exposure. However, neither cold nor heat stress affected both the body weight gain and the spleen weight in our mice.

IPH2101, a Novel Anti-Inhibitory KIR Monoclonal Antibody, and Lenalidomide Combine to Enhance the Natural Killer (NK) Cell Versus Multiple Myeloma (MM) Effect.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3870-3870 ◽  
Author(s):  
Don Benson ◽  
Courtney E Bakan ◽  
Shuhong Zhang ◽  
Lana Alghothani ◽  
Jing Liang ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Nk Cells ◽  
Tumor Cells ◽  
Nk Cell ◽  
Phase 1 ◽  
Granzyme B ◽  
Cell Activity ◽  
Target Cells ◽  
Nk Cell Activity ◽  
Immune Complex Formation

Abstract Abstract 3870 Poster Board III-806 Background NK cell activity against tumor cells is regulated by a balance of inhibitory and activating signals mediated by receptors on NK cells that recognize inhibitory and activating ligands expressed by cancer cells. IPH2101 (1-7F9) is a novel monoclonal anti-inhibitor KIR blocking antibody that has been shown to augment NK cell function against MM targets. Moreover, lenalidomide has been shown to expand and activate NK cells in vivo and in vitro. We have previously reported that the combination of IPH2101 and lenalidomide enhances NK cell mediated cytotoxicity against MM cells compared to each agent alone (Zhang et al., AACR 2009). We expand our studies to investigate potential mechanisms for the enhancement of NK cell activity by the combination of IPH2101 and lenalidomide. Methods The effects of IPH2101 and lenalidomide alone and in combination were studied using primary human NK cells from healthy donors as well as from MM patients. The MM cell lines U266 and RPMI 8226 as well as primary tumor cells from marrow aspirates of MM patients served as target cells. The effect of lenalidomide on MM activating and inhibitory ligand expression was studied by flow cytometry. NK cell trafficking was investigated with standard transwell plate migration assay. Immune complex formation between NK cell effectors and MM tumor targets was characterized by flow cytometry in control conditions and with NK cells pre-treated with IPH2101 and lenalidomide. The effects of IPH2101 and lenalidomide were studied regarding interferon-gamma and granzyme B production by ELISPOT and target-specific cytotoxicity studies were conducted to complement effector-based assays. Results IPH2101 (30 ug/ml) significantly enhanced cytotoxicity against U266 cells and primary MM tumor cells by both purified NK cells at effector:target (E:T) ratios of 10:1 or less, and also of freshly isolated peripheral blood mononuclear cells (PBMC) at E:T ratios of 60:1 or less, from more than 10 random donors. In addition, treatment of PBMC with 5-10 μmol/L lenalidomide for 72h without interleukin (IL)-2 increased NK cell lysis of U266. Treatment of PBMC from normal donors did not enhance the expression of the NK receptors KIR, NKG2D, NCR, TRAIL, and DNAM-1. Incubation of U266 cells with lenalidomide (5 uM) for 3-5 days resulted in significant enhancement of cytotoxicity by normal donor NK cells. This was associated with upregulation of the activating ligands, MICA, ULBP-2, DR4, and CD112. Using blocking antibodies to NKG2D, TRAIL, and DNAM-1, lenalidomide enhancement of MM cell killing was abrogated indicating the importance of the modulation of the ligands to the latter receptors by lenalidomide. Although IPH2101 and lenalidomide did not significantly increase NK cell migration into normal media, migration was enhanced 2.98-fold (+/− 0.36, p < 0.05) towards U266 cell targets (n= 3, p < 0.05) and MM patient serum 3.2-fold (+/− 0.4, n=3, p < 0.05). IPH2101 and lenalidomide also led to a 2.3-fold (+/− 0.43, p < 0.05) increase in immune complex formation between NK cells and MM tumor cells. IPH2101 and lenalidomide also augmented NK cell interferon gamma production against MM (control mean 303 spots/well +/− 13 versus 525 +/− 83, n=3, p < 0.05) and granzyme B production (control mean 115 +/− 98 versus 449 +/−72, n=3, p < 0.05). Importantly, in all experiments described herein, the effects of IPH2101 and lenalidomide together were greater than either agent alone. Conclusions Taken together, our data suggest that IPH2101 and lenalidomide may exert complementary mechanisms on both effector and target cells to enhance NK cell mediated killing of MM cells. Moreover, these agents have no predicted clinical cross-toxicities. A single-agent phase 1 clinical trial of IPH2101 has shown the mAb to be safe and well tolerated in MM patients. These findings support a phase 1/2 clinical trial of IPH2101 with lenalidomide as a first dual-innate immunotherapy for patients with MM. Disclosures: Andre: Innate Pharma: Employment. Squiban:Innate pharma: Employment. Romagne:Innate Pharma: Employment.

scholarly journals Dose of Retroviral Infection Determines Induction of Antiviral NK Cell Responses

2017 ◽  
Vol 91 (22) ◽  
Author(s):  
Elisabeth Littwitz-Salomon ◽  
Simone Schimmer ◽  
Ulf Dittmer
Keyword(s):  
Nk Cells ◽  
Cell Activation ◽  
Nk Cell ◽  
Cell Activity ◽  
High Dose ◽  
Nk Cell Activity ◽  
Retroviral Infection ◽  
Cell Functions ◽  
Virus Dose ◽  
Antiviral Activities

ABSTRACT Natural killer (NK) cells are part of the innate immune system and recognize virus-infected cells as well as tumor cells. Conflicting data about the beneficial or even detrimental role of NK cells in different infectious diseases have been described previously. While the type of pathogen strongly influences NK cell functionality, less is known about how the infection dose influences the quality of a NK cell response against retroviruses. In this study, we used the well-established Friend retrovirus (FV) mouse model to investigate the impact of virus dose on the induction of antiviral NK cell functions. High-dose virus inoculation increased initial virus replication compared to that with medium- or low-dose viral challenge and significantly improved NK cell activation. Antiviral NK cell activity, including in vivo cytotoxicity toward infected target cells, was also enhanced by high-dose virus infection. NK cell activation following high-dose viral challenge was likely mediated by activated dendritic cells (DCs) and macrophages and the NK cell-stimulating cytokines interleukin 15 (IL-15) and IL-18. Neutralization of these cytokines decreased NK cell functions and increased viral loads, whereas IL-15 and IL-18 therapy improved NK cell activity. Here we demonstrate that virus dose positively correlates with antiviral NK cell activity and function, which are at least partly driven by IL-15 and IL-18. Our results suggest that NK cell activity may be therapeutically enhanced by administering IL-15 and IL-18 in virus infections that inadequately activate NK cells. IMPORTANCE In infections with retroviruses, like HIV and FV infection of mice, NK cells clearly mediate antiviral activities, but they are usually not sufficient to prevent severe pathology. Here we show that the initial infection dose impacts the induction of an antiviral NK cell response during an acute retroviral infection, which had not investigated before. High-dose infection resulted in a strong NK cell functionality, whereas no antiviral activities were detected after low- or medium-dose infection. Interestingly, DCs and macrophages were highly activated after high-dose FV challenge, which corresponded with increased levels of NK cell-stimulating cytokines IL-15 and IL-18. IL-15 and IL-18 neutralization decreased NK cell functions, whereas IL-15 and IL-18 therapy improved NK cell activity. Here we show the importance of cytokines for NK cell activation in retroviral infections; our findings suggest that immunotherapy combining the well-tolerated cytokines IL-15 and IL-18 might be an interesting approach for antiretroviral treatment.

scholarly journals Patients with a deficiency of natural killer cell activity lack the VEP13-positive lymphocyte subpopulation

Blood ◽  
1985 ◽  
Vol 65 (1) ◽  
pp. 65-70 ◽  
Author(s):  
HW Ziegler-Heitbrock ◽  
H Rumpold ◽  
D Kraft ◽  
C Wagenpfeil ◽  
R Munker ◽  
...  
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Nk Cell ◽  
Natural Killer Cell Activity ◽  
Killer Cell ◽  
Cell Activity ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Target Cells ◽  
Nk Cell Activity

Many patients with B-type chronic lymphocytic leukemia (CLL) exhibit a profound defect in their natural killer (NK) cell activity, the basis of which is still obscure. Hence, we analyzed the NK cells from peripheral blood samples from 11 patients with CLL for phenotype and function, after removal of the leukemic cells with a monoclonal antibody (BA-1) plus complement. Phenotypic analysis of these nonleukemic cells with monoclonal antibodies (MoAbs) against NK cells revealed that the CLL patients had higher percentages of HNK-1-positive cells (23.5% compared to controls with 14.7%). In contrast, VEP13- positive cells were absent or low in seven patients (0.8% compared to controls with 11.2%) and normal in four patients (10.5%). When testing NK cell activities against K562 or MOLT 4 target cells, patients with no or minimal numbers of VEP13-positive cells were found to be deficient, while patients with normal percentages of VEP13-positive cells had NK cell activity comparable to controls. Isolation by fluorescence-activated cell sorter of HNK-1-positive cells from patients lacking VEP13-positive cells and NK cell activity indicated that the majority of the HNK-1-positive cells in these patients had the large granular lymphocyte morphology that is characteristic of NK cells. Thus, the deficiency of NK cell activity in CLL patients appears to result from the absence of cells carrying the VEP13 marker.

scholarly journals Selinexor Enhances NK Cell Activation Against Lymphoma Cells Via Downregulation of HLA-E

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2411-2411
Author(s):  
Jack Fisher ◽  
Christopher J. Walker ◽  
Peter Johnson ◽  
Mark S Cragg ◽  
Francesco Forconi ◽  
...  
Keyword(s):  
Nk Cells ◽  
Peripheral Blood ◽  
Research Funding ◽  
Cell Activation ◽  
Nk Cell ◽  
Cell Activity ◽  
Fold Increase ◽  
Target Cells ◽  
Lymphoma Cells ◽  
Pre Treatment

Abstract Introduction: Natural killer (NK) cells are powerful immune effectors which induce direct cytotoxicity, promote adaptive immune responses and mediate antibody dependent cellular cytotoxicity (ADCC). Enhancement of NK cell activity against cancer is currently the focus of intense research efforts and strategies include CAR-NK, stimulatory antibodies, cytokines and checkpoint inhibitors. Upregulation of exportin-1 (XPO1) is common in human cancers and high expression is negatively associated with survival in various cancers including diffuse large B cell lymphoma (DLBCL). Targeted inhibition of XPO1 by the selective inhibitor selinexor leads to cancer cell death via accumulation of tumour suppressor proteins in the nucleus, dysregulation of growth regulatory proteins and blockade of oncogene protein translation. The therapeutic efficacy of XPO1 inhibition has led to FDA approval of the oral XPO1 inhibitor selinexor for the treatment of multiple myeloma and DLBCL. The effect of selinexor on NK cell activity has not previously been investigated and was therefore addressed in this study. Methods: The B lymphoma cell lines JeKo-1, SU-DHL-4 and Ramos were incubated with selinexor (50-2000nM) for 18 hours before analysis. Flow cytometry was used to assess cell surface expression of activating and inhibitory ligands for NK cells. For NK based assays, peripheral blood derived NK cells were isolated from healthy donors and incubated with IL-15 (1ng/ml) overnight prior to co-culture with target lymphoma cells for a further 4 hours. Cytotoxicity was assessed using propidium iodide staining of target cells and degranulation of NK cells was assessed by measurement of CD107a. Whole blood samples from colorectal cancer patients (n=11) at pre-treatment and 3 weeks post selinexor monotherapy were assessed by flow cytometry for CD45+CD3-CD19-CD56+ NK cells. Results: Selinexor pre-treatment of target lymphoma cells significantly increased NK cell mediated cytotoxicity against SU-DHL-4 (2.2 Fold increase, p&lt;0.01), JeKo-1 (2 Fold increase, p&lt;0.01) and Ramos (1.7 Fold increase, p&lt;0.01) cells. In accordance with this, selinexor pre-treatment of target cells also increased the activation of NK cells against SU-DHL-4, JeKo-1 and Ramos cells as measured by CD107a expression in both CD56 bright and CD56 dim NK cell sub-groups. To identify the mechanism behind this, we measured expression of activating and inhibitory ligands for NK cells on SU-DHL-4 cells after incubation with selinexor. No significant changes in expression of activating ligands (MICA/B, ULBP-2/5/6, ULBP-1, Vimentin, B7H6, CD54) were evident. In contrast, selinexor significantly (p&lt;0.001) reduced the surface expression of HLA-E on SU-DHL-4 cells by 50%. Selinexor mediated downregulation of HLA-E was also evident in Ramos (60% reduction, p&lt;0.001) and JeKo-1 cells (20% reduction, p&lt;0.01). HLA-E binds the ITIM containing receptor NKG2A, a key inhibitory receptor for NK cells and subsets of T cells. In accordance with this, selinexor pre-treatment of SU-DHL-4 cells selectively increased NKG2A+ NK cell activation (p&lt;0.01) following co-culture. To examine the effect of selinexor on NK cells in patients, we assessed the proportion of NK cells in the peripheral blood of 11 colorectal cancer patients at pre-treatment and three weeks post selinexor monotherapy. % NK cells of CD45+ peripheral blood lymphocytes following treatment with selinexor was increased 2-fold (Median 5% pre-treatment vs 10% post selinexor). In addition, increased abundance of the less mature and less cytotoxic CD56 bright subset of NK cells was associated with poor response to therapy (Median 4% responders (n=3) vs 20% non-responders (n=8)). Larger patient datasets are required to confirm these effects and this analysis is currently ongoing. The effect of selinexor on NK cells in patients with lymphoma is also currently under investigation. Conclusions: The NKG2A:HLA-E axis is a novel immune checkpoint target and our data identifies that selinexor sensitises lymphoma cells to NK cell mediated killing via disruption of this interaction. In addition, we provide initial evidence that NK cells may be associated with clinical response to selinexor. This data indicates that NK cells may contribute to the therapeutic efficacy of selinexor and that selinexor may synergise with NK cell targeted therapies for the treatment of lymphoma. Disclosures Walker: Karyopharm Therapeutics: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Johnson: Morphosys: Honoraria; Kymera: Honoraria; Kite Pharma: Honoraria; Incyte: Honoraria; Genmab: Honoraria; Celgene: Honoraria; Bristol-Myers: Honoraria; Epizyme: Consultancy, Research Funding; Boehringer Ingelheim: Consultancy; Novartis: Honoraria; Takeda: Honoraria; Oncimmune: Consultancy; Janssen: Consultancy. Cragg: BioInvent International: Consultancy, Research Funding; GSK: Research Funding; UCB: Research Funding; iTeos: Research Funding; Roche: Research Funding. Forconi: Novartis: Honoraria; Roche: Honoraria; Janssen: Consultancy, Honoraria, Speakers Bureau; AbbVie: Consultancy, Honoraria, Speakers Bureau; Gilead: Research Funding. Landesman: Karyopharm Therapeutics: Current Employment, Current equity holder in publicly-traded company. Blunt: Karyopharm Therapeutics: Research Funding.

Increase In NK Cell Lysis of Leukemic Blasts Due to Loss of Mismatched HLA Haplotype After Haplo-Identical Stem Cell Transplantation

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2540-2540
Author(s):  
Yoshiyuki Takahashi ◽  
Itzel Bustos Villalobos ◽  
Sayoko Doisaki ◽  
Hideki Muramatsu ◽  
Akira Shimada ◽  
...  
Keyword(s):  
Nk Cells ◽  
Nk Cell ◽  
Immune Surveillance ◽  
Cell Activity ◽  
Leukemic Cells ◽  
Target Cells ◽  
Chromosome 6 ◽  
Nk Cell Activity ◽  
Before And After ◽  
Hla Loss

Abstract Abstract 2540 Introduction: Hematopoietic stem cell transplantation (HSCT) from HLA haplo-identical family donors is promising as a therapy for patients with leukemia who are at high risk for relapse. The lower relapse rates and improved survival, especially for patients with acute myelogenous leukemia (AML) who have received HSCT from killer cell immunoglobulin-like receptor (KIR) ligand-mismatched donors, suggest that donor NK cells that are alloreactive against the recipient's cells cause graft-versus-leukemia effects. An Italian group and we identified genomic loss of the patient-specific HLA haplotype in leukemic cells after haplo-identical HSCT. Analysis using SNP arrays revealed that the HLA loss in 29 to 66% of relapsed patients after haplo-identical HSCT was caused by segmental uniparental disomy (UPD) of the HLA region on chromosome 6. This suggested that leukemic cells often escape immunosurveillance through the loss of the mismatched HLA haplotype via the UDP mechanism after haplo-identical HSCT (Vago et al. N Engl J Med. 2009, Villalobos, IB et al. Blood 2010). Since NK cell effector function is tightly regulated by inhibitory KIRs on NK cells that bind to MHC class I on target cells, the escape of leukemic cells from immune surveillance by losing a mismatched HLA antigen might enhance the cytotoxicity of NK cells towards target cells. We examined alterations in donor-derived alloreactive NK cell activity against leukemic blasts of AML patients who relapsed after HLA haplo-identical HSCT. Patients and methods: We enrolled three patients with AML, aged 2, 3 and 12 years, who relapsed after HLA haplo-identical HSCT with T cell depletion of rabbit ATG in vivo. Two patients had AML M7 and the other had M0. Only one donor was KIR ligand-mismatched. Engraftment was achieved in all three patients within 28 days. Relapse occurred 35, 372 and 445 days after HSCT. Mononuclear cells were obtained from both donors and patients before and after HSCT. The NK cells were purified using NK cell selection kits (DYNAL) and measured by conventional 51Cr release assays of leukemic blasts from the patients and the control cell line K562. The mismatched HLA expression between patients and donors on hematopoietic cells was monitored by flow cytometry using anti-HLA antibody (One Lambda). Results: The mean of NK cell killing of the patients' leukemic cells at the same effector target ratio of 10 was significantly higher in donors (50.3%) than in relapsed patients (9.7%). Monitoring of alloreactive NK cell activity after HSCT showed that donor-derived NK cell killing against the patients' leukemic cells gradually decreased in the KIR ligand-mismatched setting. Relapse was minimal but obvious according to HLA monitoring of hematopoietic cells on day 98, which was 7 days after alloreactive NK cell activity was diminished in the patients. Monitoring HLA expression after HSCT also revealed that one patient had leukemic blasts at relapse with loss of the patient's specific HLA haplotype caused by UDP of the HLA region on chromosome 6. Notably, primary leukemic blasts in this patient were not killed by the donor NK cells (2.3%), but leukemic blasts at relapse were efficiently killed (69.0%) after HLA loss of leukemic cells. On the other hand, killing of leukemic blasts at relapse by the patient's NK cells after transplantation was much less effective (19.0%) than that by donor NK cells, although they originated from the same donor (Figure). Because haplotype loss of HLA caused by UDP does not change the status of the KIR ligand in patients with homozygous HLA-Cw, we further examined the expression of ULBP1-3 that are ligands for the activating NK receptor, NKG2D, on leukemic blasts before and after HLA loss. We found upregulated ULBP-2 expression on leukemic cells after the loss of HLA. Conclusions: Donor NK cells efficiently killed patients' AML blasts at relapse but NK cell activity in patients against their own leukemic blasts was impaired after HSCT. These findings indicate a rationale for donor NK cell infusions after HLA haplo-identical HSCT to avoid decreasing NK cell alloreactivity and to prevent the escape of leukemic cells from allo-immune surveillance by donor cytotoxic T lymphocytes. Disclosures: No relevant conflicts of interest to declare.

Azacytidine Compromises NK-Cell Activity in AML and MDS Patients Undergoing MRD-Based Pre-Emptive Treatment After Allogeneic Stem Cell Transplantation

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4122-4122
Author(s):  
Katja Sockel ◽  
Claudia Schönefeldt ◽  
Sieghart Sopper ◽  
Martin Wermke ◽  
Marc Schmitz ◽  
...  
Keyword(s):  
Stem Cell ◽  
Stem Cell Transplantation ◽  
Nk Cells ◽  
Cell Function ◽  
Nk Cell ◽  
Cell Activity ◽  
Nk Cell Activity ◽  
Activating Receptors

Abstract Abstract 4122 The hypomethylating agent azacytidine (AZA) represents the standard treatment for many high-risk MDS and AML patients. While the clinical efficacy has been confirmed in several studies, the precise molecular mechanism of action has not been fully understood yet. Human NK-cells play an important role in the regulation of immune responses against malignant cells. Their function is controlled by a complex interplay of activating and inhibitory receptors - some of them being regulated by methylation of the respective genes. We, therefore explored, whether AZA modulates in vitro NK-cell function as well as in vivo during minimal-residual disease (MRD)-guided treatment of imminent relapse in MDS and AML patients treated within the prospective RELAZA trial (NCT00422890). Methods: After purifying NK-cells of healthy donors by MACS (magnetic cell sorting), NK-cells were exposed in vitro to different concentrations of AZA (100nM, 1μM, 3μM) with or without IL-2. In parallel, the NK-cell phenotype of patients (n=12) with AML or MDS, undergoing MRD-guided treatment with AZA after stem cell transplantation was monitored by FACS from peripheral blood samples on day 1, 5 and 7 of the first and second AZA cycle. All patients were still in complete haematological remission at the time of therapy. Results: In vitro, we observed a significant reduction (3,1% to 1,8% p=0.028) of the immature and cytokine-regulating CD56bright NK-cell subpopulation with increasing concentrations of AZA. There was a trend towards a reduced expression of the death-ligand TRAIL, the activating receptors NKG2D and NKp46 and for an increased expression of the inhibitory KIR CD158b1/b2, whereas we could not detect any changes in the expression of FAS-L, Perforin, Granzyme B, NKp30, NKp44, CD69, CD57, DNAM-1, CD16, and NKG2A-CD94. Confirmatory, we observed a significant decrease in the expression of TRAIL (p=0.003), NKG2D (p=0.03) and NKp46 (p=0.006) during AZA treatment in-vivo. Interestingly, these changes appeared to be reversible. The observed reduction of NK-cell activating receptors and TRAIL during AZA treatment correlated with a reduction or stable course of MRD in all analyzed patients. Conclusion: In summary these data suggest that the clinical effects of AZA are not mediated by enhancing NK-cell activity. In fact, the drug may have inhibitory effects on NK-cell function which should be considered when applying AZA in the post-transplant setting. Disclosures: Platzbecker: Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Cellular and antibody mediated cytotoxicity in autoimmune thyroid disease

1987 ◽  
Vol 116 (1_Suppl) ◽  
pp. S133-S138 ◽  
Author(s):  
Ulrich Bogner ◽  
Jack R. Wall ◽  
Horst Schleusener
Keyword(s):  
Hashimoto’S Thyroiditis ◽  
Nk Cell ◽  
Cell Activity ◽  
Antithyroid Drug ◽  
Normal Subjects ◽  
Hashimoto's Thyroiditis ◽  
Target Cells ◽  
Graves Disease ◽  
Nk Cell Activity ◽  
Specific Lysis

Abstract. Antibody-dependent cell-mediated cytotoxicity (ADCC) and natural killer (NK) cell-mediated cytotoxicity was measured in patients with Hashimoto's thyroiditis (HT) and Graves' disease (GD) using a cytotoxicity assay against thyroid target cells. In the ADCC assay, mean ± sd specific lysis produced by sera from patients with HT was 21.7 ± 10% compared t 6.2 ± 3.9% from normal subjects. In the NK assay, cytotoxicity was significantly increased using lymphocytes from HT patients as effector cells. At effector: target (E:T) cell ratios of 50:1 and 25:1, mean specific lysis ± sd was 18.3 ± 14.3% and 14 ± 11.6%, respectively, compared to 3.7 ±2.1 and 3.1 ± 2.1, respectively, for normals. In Graves' disease, 9 of 19 patients had elevated cytotoxicity, whereas no significant changes of ADCC could be found either, as determined in thyrotoxic patients, after 6 months and at the end of a one-year antithyroid drug treatment. Eight of 19 patients showed normal cytotoxicity (mean % specific lysis 2.5 ± 3.1% compared to 2 ± 2.9% in normal controls) and low titres of microsomal antibodies (Mab), 3 patients had significantly increased cytotoxicity (mean specific lysis 27.6 ± 10%) in the presence of high titres of Mab, whereas 8 patients evidenced high values for cytoxicity (mean specific lysis 24.5 ± 14.1%) but low titres of Mab. NK cell activity, determined in euthyroid Graves' disease patients either under antithyroid drug therapy or in remission, was not significantly different than that of normal subjects at all E:T cell ratios. In conclusion, we demonstrated increased ADCC and NK cell activity in Hashimoto's thyroiditis but normal NK cell activity in euthyroid Graves' disease. Like in HT, ADCC is associated with titres of Mab in sera of Graves' disease patients but was also detectable in Mab-negative sera, which led us to suggest that a hitherto unknown cytotoxic antibody exists which is not measurable by passive haemagglutination for Mab.

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