Vaccination with Live Leishmania major and CpG DNA Promotes Interleukin-2 Production by Dermal Dendritic Cells and NK Cell Activation

ABSTRACT Cutaneous leishmaniasis due to Leishmania major is an emerging, chronic parasitic disease that causes disfigurement and social stigmatization. Drug therapy is inadequate, and there is no vaccine. Inoculation of virulent parasites (leishmanization) is the only intervention that has ever provided protection, because it mimics natural infection and immunity, but it was discontinued due to safety concerns (uncontrolled vaccinal lesions). In an effort to retain the benefits (immunity) while avoiding the side effects (lesions) of leishmanization, we immunized C57BL/6 mice with L. major and CpG DNA (Lm/CpG). This combination prevented lesions while inducing immunity. Also, the vaccination with live parasites and the Toll-like receptor 9 agonist enhanced innate immune responses by activating dermal dendritic cells (DCs) to produce cytokines. Here we report that the Lm/CpG vaccine induced dermal DCs, but not bone marrow-derived DCs, to produce interleukin-2 (IL-2). The release of this unusual DC-derived cytokine was concomitant with a peak in numbers of NK cells that produced gamma interferon (IFN-γ) and also enhanced activation of proliferation of IFN-γ+ CD4+ T cells. Parasite growth was controlled in Lm/CpG-vaccinated animals. This is the first demonstration of the ability of dermal DCs to produce IL-2 and of the activation of NK cells by vaccination in the context of leishmaniasis. Understanding how the Lm/CpG vaccine enhances innate immunity may provide new tools to develop vaccines against L. major, other chronic infectious diseases, or other conditions, such as cancer.

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Dengue Virus-Infected Dendritic Cells, but Not Monocytes, Activate Natural Killer Cells through a Contact-Dependent Mechanism Involving Adhesion Molecules

mBio ◽

10.1128/mbio.00741-17 ◽

2017 ◽

Vol 8 (4) ◽

Cited By ~ 25

Author(s):

Vivian Vasconcelos Costa ◽

Weijian Ye ◽

Qingfeng Chen ◽

Mauro Martins Teixeira ◽

Peter Preiser ◽

...

Keyword(s):

Dendritic Cells ◽

Virus Infection ◽

Dengue Virus ◽

Nk Cells ◽

Adhesion Molecules ◽

Cell Activation ◽

Nk Cell ◽

Denv Infection ◽

Ifn Γ

ABSTRACT Natural killer (NK) cells play a protective role against dengue virus (DENV) infection, but the cellular and molecular mechanisms are not fully understood. Using an optimized humanized mouse model, we show that human NK cells, through the secretion of gamma interferon (IFN-γ), are critical in the early defense against DENV infection. Depletion of NK cells or neutralization of IFN-γ leads to increased viremia and more severe thrombocytopenia and liver damage in humanized mice. In vitro studies using autologous human NK cells show that DENV-infected monocyte-derived dendritic cells (MDDCs), but not monocytes, activate NK cells in a contact-dependent manner, resulting in upregulation of CD69 and CD25 and secretion of IFN-γ. Blocking adhesion molecules (LFA-1, DNAM-1, CD2, and 2β4) on NK cells abolishes NK cell activation, IFN-γ secretion, and the control of DENV replication. NK cells activated by infected MDDCs also inhibit DENV infection in monocytes. These findings show the essential role of human NK cells in protection against acute DENV infection in vivo, identify adhesion molecules and dendritic cells required for NK cell activation, and delineate the sequence of events for NK cell activation and protection against DENV infection. IMPORTANCE Dengue is a mosquito-transmitted viral disease with a range of symptoms, from mild fever to life-threatening dengue hemorrhagic fever. The diverse disease manifestation is thought to result from a complex interplay between viral and host factors. Using mice engrafted with a human immune system, we show that human NK cells inhibit virus infection through secretion of the cytokine gamma interferon and reduce disease pathogenesis, including depletion of platelets and liver damage. During a natural infection, DENV initially infects dendritic cells in the skin. We find that NK cells interact with infected dendritic cells through physical contact mediated by adhesion molecules and become activated before they can control virus infection. These results show a critical role of human NK cells in controlling DENV infection in vivo and reveal the sequence of molecular and cellular events that activate NK cells to control dengue virus infection. IMPORTANCE Dengue is a mosquito-transmitted viral disease with a range of symptoms, from mild fever to life-threatening dengue hemorrhagic fever. The diverse disease manifestation is thought to result from a complex interplay between viral and host factors. Using mice engrafted with a human immune system, we show that human NK cells inhibit virus infection through secretion of the cytokine gamma interferon and reduce disease pathogenesis, including depletion of platelets and liver damage. During a natural infection, DENV initially infects dendritic cells in the skin. We find that NK cells interact with infected dendritic cells through physical contact mediated by adhesion molecules and become activated before they can control virus infection. These results show a critical role of human NK cells in controlling DENV infection in vivo and reveal the sequence of molecular and cellular events that activate NK cells to control dengue virus infection.

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Natural-killer cells and dendritic cells: “l'union fait la force”

Blood ◽

10.1182/blood-2005-03-1154 ◽

2005 ◽

Vol 106 (7) ◽

pp. 2252-2258 ◽

Cited By ~ 386

Author(s):

Thierry Walzer ◽

Marc Dalod ◽

Scott H. Robbins ◽

Laurence Zitvogel ◽

Eric Vivier

Keyword(s):

Dendritic Cells ◽

Nk Cells ◽

Natural Killer ◽

Cell Activation ◽

Nk Cell ◽

Interleukin 12 ◽

Cell Contact ◽

Ifn Γ

AbstractSeveral recent publications have focused on the newly described interactions between natural-killer (NK) cells and dendritic cells (DCs). Activated NK cells induce DC maturation either directly or in synergy with suboptimal levels of microbial signals. Immature DCs appear susceptible to autologous NK-cell-mediated cytolysis while mature DCs are protected. NK-cell-induced DC activation is dependent on both tumor necrosis factor-α (TNF-α)/interferon-γ (IFN-γ) secretion and a cell-cell contact involving NKp30. In vitro, interleukin-12 (IL-12)/IL-18, IL-15, and IFN-α/β production by activated DCs enhance, in turn, NK-cell IFN-γ production, proliferation, and cytotoxic potential, respectively. In vivo, NK-cell/DC interactions may occur in lymphoid organs as well as in nonlymphoid tissues, and their consequences are multiple. By inducing DC activation, NK-cell activation induced by tumor cells can indirectly promote antitumoral T-cell responses. Reciprocally, DCs activated through Toll-like receptors (TLRs) induce potent NK-cell activation in antiviral responses. Thus, DCs and NK cells are equipped with complementary sets of receptors that allow the recognition of various pathogenic agents, emphasizing the role of NK-cell/DC crosstalk in the coordination of innate and adaptive immune responses.

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NK cell activation by dendritic cells (DCs) requires the formation of a synapse leading to IL-12 polarization in DCs

Blood ◽

10.1182/blood-2004-01-0380 ◽

2004 ◽

Vol 104 (10) ◽

pp. 3267-3275 ◽

Cited By ~ 230

Author(s):

Christophe Borg ◽

Abdelali Jalil ◽

Diego Laderach ◽

Kouji Maruyama ◽

Hiro Wakasugi ◽

...

Keyword(s):

Dendritic Cells ◽

Nk Cells ◽

Neutralizing Antibodies ◽

Cell Activation ◽

Nk Cell ◽

Critical Role ◽

Interleukin 12 ◽

Loss Of Function ◽

Knock Out ◽

Ifn Γ

Abstract Mature dendritic cells (mDCs) can trigger the effector functions of natural killer (NK) cells. Knock-out, small-interfering RNA or neutralizing antibodies targeting interleukin 12 (IL-12) subunits revealed a critical role for IL-12 in NK cell interferon γ (IFN-γ) secretion promoted by mDCs. However, NK cell activation by DCs also required direct cell-to-cell contacts. DC-mediated NK cell activation involved the formation of stimulatory synapses between DCs and NK cells. The formation of DC/NK cell conjugates depended on cytoskeleton remodeling and lipid raft mobilization in DCs. Moreover, the disruption of the DC cytoskeleton using pharmacologic agents or the loss-of-function mutation of the Wiskott-Aldrich syndrome protein abolished the DC-mediated NK cell activation. Synapse formation promoted the polarized secretion of preassembled stores of IL-12 by DCs toward the NK cell. The synaptic delivery of IL-12 by DCs was required for IFN-γ secretion by NK cells, as assessed using inhibitors of cytoskeleton rearrangements and transwell experiments. Therefore, the cross-talk between DCs and NK cells is dictated by functional synapses. (Blood. 2004;104:3267-3275)

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Stem Cell Factor Enhances Interleukin-2–Mediated Expansion of Murine Natural Killer Cells In Vivo

Blood ◽

10.1182/blood.v90.9.3647 ◽

1997 ◽

Vol 90 (9) ◽

pp. 3647-3653 ◽

Cited By ~ 26

Author(s):

Todd A. Fehniger ◽

William E. Carson ◽

Ewa Mrózek ◽

Michael A. Caligiuri

Keyword(s):

Nk Cells ◽

Cell Expansion ◽

Stem Cell Factor ◽

Low Dose ◽

Nk Cell ◽

Interleukin 2 ◽

Innate Immune ◽

Ifn Γ

Abstract The administration of low dose interleukin-2 (IL-2) results in a selective expansion of natural killer (NK) cells in vivo, and promotes the differentiation of NK cells from hematopoietic precursor cells in vitro. We have previously shown that stem cell factor (SCF ), the ligand to the c-kit tyrosine kinase receptor, enhances IL-2–induced NK cell proliferation and differentiation in vitro. Here, we investigated the effects of SCF plus IL-2 delivered to mice in vivo. Eight-week-old C57BL/6 mice were treated with a continuous subcutaneous infusion of IL-2 (1 × 104 IU/d) plus a daily intraperitoneal dose of SCF (100 μg/kg/d), IL-2 alone, SCF alone, or vehicle alone for 8 weeks. The in vivo serum concentration of IL-2 ranged between 352 ± 12.0 pg/mL and 606 ± 9.0 pg/mL, achieving selective saturation of the high affinity IL-2 receptor, while the peak SCF serum concentration was 296 ± 13.09 ng/mL. Alone, the daily administration of SCF had no effect on the expansion of NK cells. The continuous infusion of IL-2 alone did result in a significant expansion of NK1.1+CD3− cells compared to mice treated with placebo or SCF. However, mice treated with both SCF and IL-2 showed an increase in the absolute number of NK cells that was more than twofold that seen with IL-2 alone, in the spleen (P ≤ .005), bone marrow (P ≤ .025), and blood (P < .05). NK cytotoxic activity against YAC-1 target cells was significantly higher for mice treated with SCF plus IL-2, compared to mice treated with IL-2 alone (P ≤ .0005). Interferon-γ (IFN-γ) production in cytokine-activated splenocytes was also greater for the SCF plus IL-2 group, over IL-2 treatment alone (P ≤ .01). The effect of SCF plus IL-2 on NK cell expansion was likely mediated via NK cell precursors, rather than mature NK cells. In summary, we provide the first evidence that SCF can significantly enhance expansion of functional NK cells induced by the prolonged administration of low dose IL-2 in vivo. Since the NK cell is a cytotoxic innate immune effector and a potent source of IFN-γ, this therapeutic strategy for NK cell expansion may serve to further enhance innate immune surveillance against malignant transformation and infection in the setting of cancer and/or immunodeficiency.

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Aberrant anti-viral response of natural killer cells in severe asthma

European Respiratory Journal ◽

10.1183/13993003.02422-2018 ◽

2020 ◽

Vol 55 (5) ◽

pp. 1802422

Author(s):

Justine Devulder ◽

Cécile Chenivesse ◽

Valérie Ledroit ◽

Stéphanie Fry ◽

Pierre-Emmanuel Lobert ◽

...

Keyword(s):

Nk Cells ◽

Natural Killer ◽

Severe Asthma ◽

Cell Activation ◽

Mononuclear Cells ◽

Nk Cell ◽

Peripheral Blood Mononuclear ◽

Healthy Donors ◽

Asthma Patients ◽

Ifn Γ

Rhinovirus infections are the main cause of asthma exacerbations. As natural killer (NK) cells are important actors of the antiviral innate response, we aimed at evaluating the functions of NK cells from severe asthma patients in response to rhinovirus-like molecules or rhinoviruses.Peripheral blood mononuclear cells from patients with severe asthma and healthy donors were stimulated with pathogen-like molecules or with the rhinoviruses (RV)-A9 and RV-2. NK cell activation, degranulation and interferon (IFN)-γ expression were analysed.NK cells from severe asthma patients were less cytotoxic than those from healthy donors in response to toll-like receptor (TLR)3, TLR7/8 or RV-A9 but not in response to RV-2 stimulation. Furthermore, when cultured with interleukin (IL)-12+IL-15, cytokines which are produced during viral infections, NK cells from patients with severe asthma were less cytotoxic and expressed less IFN-γ than NK cells from healthy donors. NK cells from severe asthmatics exhibited an exhausted phenotype, with an increased expression of the checkpoint molecule Tim-3.Together, our findings indicate that the activation of NK cells from patients with severe asthma may be insufficient during some but not all respiratory infections. The exhausted phenotype may participate in NK cell impairment and aggravation of viral-induced asthma exacerbation in these patients.

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Chlamydia psittaci-Infected Dendritic Cells Communicate with NK Cells via Exosomes To Activate Antibacterial Immunity

Infection and Immunity ◽

10.1128/iai.00541-19 ◽

2019 ◽

Vol 88 (1) ◽

Author(s):

Nadine Radomski ◽

Axel Karger ◽

Kati Franzke ◽

Elisabeth Liebler-Tenorio ◽

Rico Jahnke ◽

...

Keyword(s):

Dendritic Cells ◽

Nk Cells ◽

Nk Cell ◽

Early Response ◽

Chlamydia Psittaci ◽

Target Cells ◽

Necrosis Factor Alpha ◽

Content Type ◽

Host Cell Death ◽

Ifn Γ

ABSTRACT Dendritic cells (DCs) and natural killer (NK) cells are critically involved in the early response against various bacterial microbes. Functional activation of infected DCs and NK cell-mediated gamma interferon (IFN-γ) secretion essentially contribute to the protective immunity against Chlamydia. How DCs and NK cells cooperate during the antichlamydial response is not fully understood. Therefore, in the present study, we investigated the functional interplay between Chlamydia-infected DCs and NK cells. Our biochemical and cell biological experiments show that Chlamydia psittaci-infected DCs display enhanced exosome release. We find that such extracellular vesicles (referred to as dexosomes) do not contain infectious bacterial material but strongly induce IFN-γ production by NK cells. This directly affects C. psittaci growth in infected target cells. Furthermore, NK cell-released IFN-γ in cooperation with tumor necrosis factor alpha (TNF-α) and/or dexosomes augments apoptosis of both noninfected and infected epithelial cells. Thus, the combined effect of dexosomes and proinflammatory cytokines restricts C. psittaci growth and attenuates bacterial subversion of apoptotic host cell death. In conclusion, this provides new insights into the functional cooperation between DCs, dexosomes, and NK cells in the early steps of antichlamydial defense.

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Intravenous immunoglobulins suppress T-cell priming by modulating the bidirectional interaction between dendritic cells and natural killer cells

Blood ◽

10.1182/blood-2007-03-077057 ◽

2007 ◽

Vol 110 (9) ◽

pp. 3253-3262 ◽

Cited By ~ 57

Author(s):

Thanyalak Tha-In ◽

Herold J. Metselaar ◽

Hugo W. Tilanus ◽

Zwier M. A. Groothuismink ◽

Ernst J. Kuipers ◽

...

Keyword(s):

Dendritic Cells ◽

T Cell ◽

Nk Cells ◽

T Cell Activation ◽

Cell Activation ◽

Nk Cell ◽

Intravenous Immunoglobulins ◽

Interferon Γ ◽

T Cell Priming ◽

Induced Apoptosis

AbstractThe modes of action of intravenous immunoglobulins (IVIgs) in exerting their immunomodulatory properties are broad and not fully understood. IVIgs can modulate the function of various immune cells, including suppressing the capacity of dendritic cells (DCs) to stimulate T cells. In the present study, we showed that DCs matured in the presence of IVIgs (IVIg-DCs) activated NK cells, and increased their interferon-γ production and degranulation. The activated NK cells induced apoptosis of the majority of IVIg-DCs. In consequence, only in the presence of NK cells, IVIg-DCs were 4-fold impaired in their T-cell priming capacity. This was due to NK-cell–mediated antibody-dependent cellular cytotoxicity (ADCC) to IVIg-DCs, probably induced by IgG multimers, which could be abrogated by blockade of CD16 on NK cells. Furthermore, IVIg-DCs down-regulated the expression of NKp30 and KIR receptors, and induced the generation of CD56brightCD16−CCR7+ lymph node–type NK cells. Our results identify a novel pathway, in which IVIgs induce ADCC of mature DCs by NK cells, which downsizes the antigen-presenting pool and inhibits T-cell priming. By influencing the interaction between DCs and NK cells, IVIgs modulate the ability of the innate immunity to trigger T-cell activation, a mechanism that can “cool down” the immune system at times of activation.

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Tim-3, a Novel Immune Receptor, Is Constitutively Expressed on Human Natural Killer Cells and Functions as An Activating Coreceptor

Blood ◽

10.1182/blood.v116.21.106.106 ◽

2010 ◽

Vol 116 (21) ◽

pp. 106-106

Author(s):

Michelle Gleason ◽

Todd Lenvik ◽

Valarie McCullar ◽

Sarah Cooley ◽

Michael Verneris ◽

...

Keyword(s):

Nk Cells ◽

Board Of Directors ◽

Cell Activation ◽

Low Dose ◽

Cell Function ◽

Nk Cell ◽

Effector Function ◽

Advisory Committees ◽

Immune Receptor ◽

Ifn Γ

Abstract Abstract 106 NK cells are an attractive option for immunotherapy as they do not require pre-sensitization for anti-tumor activity and do not induce graft versus host disease (GvHD) in an allogeneic transplant setting. The potential of NK cells in controlling human hematological malignancies has been increasingly recognized in recent years, as the adoptive transfer of alloreactive NK cells in hematopoietic cell transplantation (HCT) clinical trials have demonstrated therapeutic anti-leukemia effects. NK cell function is regulated by the integration of antagonist signals received from cell surface activating and inhibitory receptors. Tim-3 is a novel immune receptor that is a member of the T cell immunoglobulin and mucin-containing domain (TIM) family of glycoproteins. While its role in T cells and antigen presenting cells has been described, little is known about its function in human NK cells. While Tim-3 is present on a variety of immune cells, resting NK cells constitutively express Tim-3 compared to other lymphocyte populations (NK: 73±3%; NKT: 6±1%; T: 1±1%; n=14) and we hypothesized that Tim-3 may be important in mediating NK cell function. The unique subset of cytokine producing CD56Bright NK cells exhibited significantly lower resting Tim-3 expression compared to CD56Dim NK cells (53±3% vs. 75±3%; p<0.001, n=14). Distinct Tim-3 expression patterns were found on resting CD56Dim NK cells and activation with low dose IL-12 (1ng/mL) and IL-18 (10ng/mL), intended to more closely mimic physiologic conditions, resulted in further differentiation of this unique expression pattern dividing NK cells into 4 distinct populations: Tim-3 was homogeneously up-regulated on all CD56Bright NK cells after activation while CD56Dim NK cells were further stratified into 3 defined populations with Tim-3hi, Tim-3lo and Tim-3neg expression. The only identified ligand of Tim-3 is galectin-9 (Gal-9), a β-galactoside binding lectin, which is expressed on a wide range of healthy and malignant cells. To investigate the potential function of Tim-3, an expression vector containing human Gal-9 was transduced into K562 and Raji cells, both without endogenous Gal-9 expression. Resting NK cytotoxicity (51Cr release) was found to be increased in the presence of Gal-9 compared to the non-Gal-9 expressing targets [E:T=0.7:1, K562 vs. K562-Gal-9: 25±3% vs. 33±3% (n=8, p<0.05); E:T=20:1, Raji vs. Raji-Gal-9: 8±1% vs. 17±2% (n=4, p<0.05)]. Analysis of CD107a degranulation showed that resting Tim-3+ CD56Bright cells were more functional against Gal-9 expressing targets than Tim-3− CD56Bright cells, suggesting that Tim-3 might also play a role in IFN-γ production. To further investigate this, resting NK cells were activated with low-dose IL-12/IL-18 overnight and IFN-γ levels were measured in response to soluble rhGal-9 (0, 2.5, 5, 10 and 20nM). Exposure to soluble rhGal-9 alone without IL-12/IL-18 did not induce IFN-γ production. For both the CD56Bright and CD56Dim IL-12/IL-18 activated NK populations, only Tim-3+ NK cells displayed a dose dependent increase in IFN-γ production upon exposure to soluble rhGal-9 compared to Tim-3− NK cells. To understand the relevance of the distinct Tim-3 populations circulating in resting blood, CD56Bright, CD56Dim/Tim-3hi, CD56Dim/Tim-3lo and CD56Dim/Tim-3neg populations were sorted, cultured overnight in IL-12/IL-18 and exposed to soluble rhGal-9. Results showed the Tim-3 expressing populations contain the predominant IFN-γ producing cells that were responsive to rhGal-9 (results for the sorted CD56Dim/Tim-3lo population shown in the figure below). This increase in IFN-γ production within the Tim-3 expressing NK cell populations was abrogated by the addition of β-lactose, a β-galactoside that binds and blocks Gal-9 activity. Lastly, Western blot and immunohistochemistry analysis of human primary acute leukemia blasts revealed high Gal-9 expression. As the presence of ligands for NK cell activating receptors on tumors provide an important prerequisite for NK cell activation and effector function, we show a novel functional role for the receptor Tim-3 in human NK cell biology in the presence of its ligand Gal-9. We, therefore, propose a model where constitutively expressed Tim-3 is up-regulated by NK cell activation and effector function is enhanced by Tim-3/Gal-9 interaction, which may potentiate the elimination of Gal-9 positive tumors by NK cells. Disclosures: Niki: GalPharma: Membership on an entity's Board of Directors or advisory committees. Hirashima:GalPharma: Membership on an entity's Board of Directors or advisory committees.

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The JAK1/JAK2 Inhibitor Ruxolitinib Substantially Affects NK Cell Biology

Blood ◽

10.1182/blood.v122.21.16.16 ◽

2013 ◽

Vol 122 (21) ◽

pp. 16-16 ◽

Cited By ~ 5

Author(s):

Kathrin Schönberg ◽

Janna Rudolph ◽

Isabelle Cornez ◽

Peter Brossart ◽

Dominik Wolf

Keyword(s):

Flow Cytometry ◽

Cell Proliferation ◽

Nk Cells ◽

Cell Activation ◽

Nk Cell ◽

Granzyme B ◽

Receptor Activation ◽

Jak2 Inhibitor ◽

Signaling Events ◽

Ifn Γ

Abstract Introduction We recently demonstrated that ruxolitinib (INCB018424), the first approved JAK1/JAK2 inhibitor for treatment of myelofibrosis (MF), exerts potent anti-inflammatory activity. This may at least in part explain higher infection rates observed in ruxolitinib-treated patients. NK cells are critical for cancer-immune surveillance and cytokine-mediated signals are central for proper NK cell activation. We here aimed to characterize in detail the effects of JAK1/2 inhibition on human NK cells. Methods Highly purified CD56+ NK cells were isolated from human peripheral buffy coats by magnetic bead isolation and subsequently exposed to increasing concentrations of ruxolitinib (0.1-10 µM). Cytokine (1000U/ml IL-2, 25ng/ml IL-15)-induced NK cell proliferation was analyzed by CFSE dilution. Phenotypic and functional NK cell activation markers (NKp46, NKG2D, Granzyme B, CD16, and CD69) were analyzed by flow cytometry (including CD107a expression for degranulation). NK cell function was tested by flow-cytometry-based killing assays and quantification of IFN-γ production upon stimulation with either MHC class I-deficient K562 target cells or cytokines (IL-12, IL-18). In addition, phenotypic and functional analyses were also tested during NK receptor activation via plate-bound activating NKp46 antibodies. Signaling events were analyzed by Western Blot analysis to detect phosphorylation of JAK1 and JAK2 as well as by applying phospho-flow technology to evaluate ruxolitinib-mediated changes of cytokine-dependent signalling cascades (pS6, pSTAT1, pSTAT3, pSTAT5, pERK, pAKT, pP38, and pZAP70). Results Our results demonstrate provide first evidence that ruxolitinib profoundly affects cytokine-induced NK cell activation. This includes a significant and dose-dependent reduction of NK cell proliferation, reduced induction of activation-associated surface markers (including NKp46, NKG2D, Granzyme B, CD16, CD69) as well as impaired killing activity against the classical NK target cell line K562. In addition, all main functional activities of NK cells are down-regulated as shown by reduced cytotoxic capacity, impaired degranulation and IFN-γ production. After wash-out, the inhibitory effects of ruxolitinib on NK cells are fully reversible, as shown by proper re-activation by cytokines. In contrast to cytokine-mediated NK cell activation, stimulation via the NK-specific receptor NKp46 are not affected by ruxolitinib. Of note, ruxolitinib does not affect NK cell viability. On a molecular level, phospho-flow analyses revealed that cytokine associated signaling events, such as phosphorylation of STAT5 and S6 were dose-dependently reduced by ruxolitinib in primary human NK cells. Conclusions Ruxolitinib strongly inhibits NK cell activation leading to impaired proliferation and functional activity. Experiments verifying these effects in patients are currently ongoing and will be presented at the meeting. Our findings may have important clinical implications, when considering the application of ruxolitinib as GvHD therapy, because NK cells are critically involved in the GvL effect after allogeneic stem cell transplantation. Disclosures: Wolf: Novartis: Honoraria, Research Funding.

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AFM13 Is the Most Advanced Bispecific NK-Cell Engaging Antibody in Clinical Development Substantially Enhancing NK-Cell Effector Function and Proliferation

Blood ◽

10.1182/blood.v128.22.1764.1764 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1764-1764 ◽

Cited By ~ 1

Author(s):

Jens Pahl ◽

Uwe Reusch ◽

Thorsten Gantke ◽

Anne Kerber ◽

Joachim Koch ◽

...

Keyword(s):

Nk Cells ◽

Cell Activation ◽

Nk Cell ◽

Target Cells ◽

Cell Cytotoxicity ◽

Cell Receptors ◽

Cell Responses ◽

Nk Cell Receptors ◽

Ifn Γ ◽

Nk Cell Cytotoxicity

Abstract Introduction: AFM13 is an NK-cell engaging CD30/CD16A bispecific tetravalent TandAb antibody currently in phase 2 clinical development in Hodgkin lymphoma (HL) and other CD30+ malignancies. It engages NK-cells through CD16A with high affinity and specificity and confers significantly stronger NK-cell activation compared to other therapeutic antibodies. We have previously shown synergistic efficacy when NK-cell activation by AFM13 is combined with check-point modulation such as anti-PD-1 treatment, which is known to unleash T cell and NK-cell activity. The goal of this study was to identify further candidates for combination treatments and biomarkers that potentially indicate NK-cell responses to AFM13 treatment. Methods: AFM13-mediated NK-cell cytotoxicity and IFN-γ production after 4-hour interaction with HL cell lines was measured by 51Cr release assays and flow cytometry, respectively. Expression of NK-cell receptors, NK-cell proliferation (CFSE dilution) and expansion (absolute cell counts) was analyzed by flow cytometry. Results: The interaction of NK-cells with AFM13-coated tumor cells up-regulated the expression of NK-cell receptors such as CD25, CD69, CD137/4-1BB as well as molecules that may serve as NK-cell check-points when compared with the unrelated NK-cell binding TandAb AFM12 that does not bind to target cells. Importantly, CD16A engagement by AFM13 enhanced the proliferation and expansion potential of NK-cells when subsequently incubated with IL-15 or with particularly low doses of IL-2. NK-cell cytotoxicity and IFN-γ production was substantially increased towards CD30+ tumor cells in the presence of AFM13. Even target cells resistant to naïve and IL-2/IL-15-activated NK-cells were susceptible to AFM13-induced NK-cell cytotoxicity. AFM13 concentrations of as low as 10-2 µg/mL resulted in maximal activity while AFM13 was significantly more potent than native anti-CD30 IgG1 antibody. NK-cell activation by IL-2 or IL-15 had a synergistic effect on AFM13-mediated cytotoxicity. Conclusion: AFM13 specifically enhances the cytotoxic, proliferative and cytokine-producing potential of NK-cells. Our data indicate that the distinctive modulation of NK-cell receptors can be utilized to monitor NK-cell responses during AFM13 therapy and provides candidates for therapeutic combination strategies. Moreover, the combination with low doses of IL-2 or with IL-15 may expand the quantity of tumor-reactive NK-cells after AFM13 treatment and promote NK-cell functionality in the tumor microenvironment in cancer patients. Disclosures Reusch: Affimed: Employment, Patents & Royalties: Patents. Gantke:Affimed GmbH: Employment. Kerber:Affimed: Employment. Koch:Affimed: Employment. Treder:Affimed: Employment. Cerwenka:Affimed: Research Funding.

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