Status Of Natural Killer Cells Research Articles

Altered natural killer (NK) cell frequency and phenotype in latent autoimmune diabetes in adults (LADA) prior to insulin deficiency

Approximately 10% of the patients diagnosed with type 2 diabetes (T2D) have detectable serum levels of glutamic acid decarboxylase 65 autoantibodies (GADA). These patients usually progress to insulin dependency within a few years, and are classified as being latent autoimmune diabetes in adults (LADA). A decrease in the frequency of peripheral blood natural killer (NK) cells has been reported recently in recent-onset T1D and in high-risk individuals prior to the clinical onset. As NK cells in LADA patients have been investigated scarcely, the aim of this study was to use multicolour flow cytometry to define possible deficiencies or abnormalities in the frequency or activation state of NK cells in LADA patients prior to insulin dependency. All patients were GADA-positive and metabolically compensated, but none were insulin-dependent at the time blood samples were taken. LADA patients exhibited a significant decrease in NK cell frequency in peripheral blood compared to healthy individuals (P=0.0018), as reported previously for recent-onset T1D patients. Interestingly, NKG2D expression was increased significantly (P<0.0001), whereas killer cell immunoglobulin-like receptor (KIR)3DL1 expression was decreased (P<0.0001) within the NK cell population. These observations highlight a defect in both frequency and activation status of NK cells in LADA patients and suggest that this immunological alteration may contribute to the development of autoimmune diabetes by affecting peripheral tolerance. Indeed, recent evidence has demonstrated a regulatory function for NK cells in autoimmunity. Moreover, the decrease in NK cell number concords with observations obtained in recent-onset T1D, implying that similar immunological dysfunctions may contribute to the progression of both LADA and T1D.

Anti-natural Killer Inhibitory Receptors in Elderly Patients with Acute Myeloid Leukaemia

Treatment with anti-killer-cell immunoglobulin-like receptor (KIR) monoclonal antibody (mAb) is a new approach aimed at harnessing the antileukaemic potential of natural killer (NK) cells for the treatment of acute myeloid leukaemia (AML). NK cell antitumour activity is regulated by a balance between activating and inhibitory receptors (KIR). 1-7F9/IPH2101 is a fully human immunoglobulin G4 (IgG4) mAb that binds to inhibitory KIR and blocks binding with its ligand (human leukocyte antigen C [HLA-C] molecule) on leukaemic cells.In vitro,and in a surrogatein vivomodel in mice, treatment with 1-7F9/IPH2101 was able to induce NK cell activation and cytotoxicity against leukaemic cells. Patients with AML often display abnormal NK cell function, while evidence of an impact of NK cell status on AML outcome has been reported in allogeneic transplantation. 1-7F9/IPH2101 is currently under clinical investigation in patients with AML. This article reviews the mechanisms of NK cell antileukaemic activity and its role and defects in AML. Currently available data on the pre-clinical and clinical development of 1-7F9/IPH2101 are presented, and the rationale for its future use as a single agent or in combination is discussed.

Long Lasting Alteration of Natural Killer Cells Post-Chemotherapy in Elderly Patients with Acute Myeloid Leukemia (AML).

Abstract 1653Poster Board I-679 BackgroundThe immune system is involved in AML control and Natural Killer (NK) cells are among the most promising effectors. The therapeutic potential of NK cells has been revealed by the Killer Immunoglobulin Receptor (KIR) mismatch allogeneic transplant model where the anti-leukemic effect of the graft, is due to unleashed NK cells towards AML blasts, as suggested by enhanced in vitro lytic activity of KIR-HLA mismatched donor NK cells against recipient blasts (Miller et al. 2005; Ruggeri et al. 2002). Receptors involved in the function of NK cells against AML blasts have been identified (Pende et al., 2005). Some of these receptors are altered in AML patients at diagnosis and might be involved in the immune escape of AML blasts (Costello et al., 2002). However, the status of NK cells during early stages of patient's chemotherapy (CT) treatment is unknown. The present study monitored status of NK cells during early stages following patient's remission after CT that may be critical for their long lasting clinical response, and results might provide new targets for immunotherapy. MethodsWe enrolled 20 elderly patients (60 to 80 years old) with non promyelocytic AML in first CR following induction and pre-consolidation CT with normal renal and hepatic functions. Patient peripheral NK, gd T and CD8 T cells were analyzed before consolidation CT and every other week after treatment for 8 weeks. 6-colors flow cytometry was performed to investigate the expression of MHC receptors (CD158a, b, e, i, CD85j and NKG2A), activating receptors (NKp30, NKp46, NKG2D, CD16, DNAM-1, 2B4) as well as their differentiation status (perforin and granzyme expression). Their function, as determined by cytotoxicity (51Cr release and CD107 expression) and cytokine production (intracellular staining of IFN-g), was analyzed using purified NK cells stimulated by K562, or in redirected assays using NKp30, NKp46 and CD16 mAbs. ResultsNK cell counts were depressed away from the induction and pre-consolidation CT as compared to NK cell counts of age-matched controls (ctl) (95±107 NK/μL vs 229±91 NK/μL respectively); they were further depressed during the first 2 weeks post-consolidation CT (55±57 NK/μL), but were back to pre-consolidation CT level at 4 weeks (105±102 NK/μL). In contrast, CD8 T cells and gd T cells counts were normal even at early times post-CT. Expression of 2B4 was depressed at all time points. In contrast, NKp30 expression was lower at diagnosis and close to ctl level post-consolidation CT (p=0.0003) and NKp46 expression increased after CT (p<0.0001).Sizes of NK cell subsets expressing CD158a or CD158b in patients post-induction and consolidation CT were smaller than those of ctl (% CD158a+: p=0.003; % CD158b+: p=0.014). In contrast the NKG2A or CD85j positive NK cell subsets were either unchanged or slightly increased respectively at all time points (p=0.0015 for CD85j+). Moreover, sizes of perforin or granzyme positive NK cell subsets were increased in treated AML patients (% Granzyme+: p= 0.0125 and % Perforin+: p=0.0268). In addition, we observed an important heterogeneity in the expression of the surface receptors among patients that is currently analyzed with respect to the duration of the CR. Finally, NK cell cytoxicity was comparable at all time points to the one of age-matched ctl. In contrast, IFN-g secretion was decreased, at all time points, against K562 or in redirected assays using CD16 mAb and almost abolished using redirected assay with NKp30 mAb. ConclusionsThis study demonstrates that in elderly AML patients in CR after CT (1) several alterations are detected at all time points, (2) NK cell number is lower and (3) IFN-g secretion is impaired. However NK cytotoxic function is comparable to age-matched controls. The likely basis of the complex pattern of modifications might rely on an interplay between the direct and indirect effects of chemotherapy, activation of immune system, NK cell differentiation and its interaction with AML blasts. Altogether this study indicates that new immunotherapeutic approaches might be used to increase NK cell numbers and functions (cytotoxicity and IFN-g secretion) at early times post-CT in elderly patients with AML. DisclosuresRomagne:Innate Pharma: Employment.

Natural killer cell‐based immunotherapy in cancer: current insights and future prospects

As our understanding of the molecular mechanisms governing natural killer (NK) cell activity increases, their potential in cancer immunotherapy is growing increasingly prominent. This review analyses the currently available preclinical and clinical data regarding NK cell-based immunotherapeutic approaches in cancer starting from a historical background and an overview of molecular mechanisms taking part in NK cell responses. The status of NK cells in cancer patients, currently investigated clinical applications such as in vivo modulation of NK cell activity, ex vivo purification/expansion and adoptive transfer as well as future possibilities such as genetic modifications are discussed in detail.

The innate natural killer cells in transplant rejection and tolerance induction

The roles of adaptive immune cells in transplant models have been extensively studied, but very little is known about the role of innate immune cells in the allograft response, especially in tolerance induction. In this review, we summarized the latest developments in the study of the role of natural killer cells in mediating graft rejection and tolerance induction. Natural killer cells are potent cytolytic cells; they also induce tissue inflammation by producing powerful proinflammatory cytokines. Thus, natural killer cells can act as effector cells in transplant rejection. Recent studies, however, have demonstrated additional roles for natural killer cells in the induction of transplant tolerance. We found that natural killer cells control survival of graft-derived donor cells and killing of donor dendritic cells by host natural killer cells inhibits direct priming of alloreactive T cells. Natural killer cells are also shown directly to suppress the activation of T cells. In other models, natural killer cells are found to regulate the induction of regulatory T cells. These new findings may have important clinical implications in tolerance induction. Natural killer cells are involved in both graft rejection and tolerance induction; such opposing effects may be mediated by differences in the activation status of natural killer cells. We believe that natural killer cells can be therapeutically modified for the induction of transplant tolerance.

Age-associated decline in natural killer (NK) activity reflects primarily a defect in function of NK cells

The possible role that natural killer (NK) cells might play in the control of tumors and certain infections prompted an investigation of the status of NK cells in aged mice of two inbred strains (C3H and C57BL/6). The frequency of NK cells in young-adult and aged mice was assessed by two methods that provided accurate estimates of the relative numbers of NK cells; (a) a functional assay procedure from which the number of lytic units could be estimated, and (b) a target-cell (YAC-1 tumor cells) binding procedure. The frequency of NK cells in the spleens of untreated mice as well as in mice infected with Trypanosoma musculi, the latter a powerful NK cell activating agent, was determined. In both strains of mice the frequency of functionally-competent NK cells declined significantly with age, to a greater extent in C3H than in C57BL/6 mice. Similarly, the potential to generate NK cells upon parasite activation was significantly less in aged than in young mice and the reduced potential was more apparent in C3H than in C57BL/6 mice. In contrast, the target cell-binding procedure showed only a modest decline in the frequency of NK cells in the spleens of aged mice of either strain. It appears, therefore, that the decline in NK activity during aging is a reflection of loss of competence to lyse targets rather than a major decline in the actual numbers of NK cells.