Expression and Immunomodulatory Function of RANKL in Leukemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 245-245
Author(s):  
Benjamin J Schmiedel ◽  
Tina Baessler ◽  
Miyuki Azuma ◽  
Lothar Kanz ◽  
Helmut R. Salih
Keyword(s):  
Nk Cells ◽  
Cell Function ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Immune Surveillance ◽  
Leukemia Cells ◽  
Target Cells ◽  
Cytotoxic Lymphocytes ◽  
Hematopoietic Malignancies ◽  
Immunomodulatory Function

Abstract Abstract 245 The TNF family member RANKL and its receptors RANK and osteoprotegerin (OPG) are key regulators of bone remodelling, but have also been shown to influence progression of malignancies like breast cancer (Tan et al., Nature 2011), myeloma (Sordillo et al., Cancer 2003) and CLL (Secchiero et al. J Cell Physiol. 2006). NK cells are cytotoxic lymphocytes that play an important role in tumor immune surveillance especially of hematopoietic malignancies. Their reactivity is influenced by a variety of activating and inhibitory molecules expressed by their target cells including several members of the TNF family. Recently, we reported that RANK, upon interaction with RANKL which can be expressed by malignant hematopoietic cells, mediates signals that impair NK reactivity (Schmiedel et al., Blood 2010 116,21:893–893). Here we extended these analyses and comprehensively studied the expression and immunomodulatory function of RANKL in leukemia. Analysis of primary leukemia cells revealed substantial RANKL surface expression in a high proportion of the investigated cases (AML, 47 of 65 (72%); ALL, 16 of 21 (76%); CML, 6 of 10 (60%); CLL, all 54 (100%)). Signaling via surface-expressed RANKL into the malignant cells mediated the release of cytokines like TNF, IL-6, IL-8 and IL-10 which have been shown to act as autocrine and paracrine growth and survival factors in leukemia. Moreover, the factors released upon RANKL signaling upregulated RANK expression on NK cells. In line, NK cells from leukemia patients (n=75) displayed significantly (p<0.001, Mann-Whitney U-test) higher RANK expression compared to healthy controls (n=30) confirming our notion that RANK-RANKL interaction may contribute to leukemia pathophysiology. We further found that RANK-RANKL interaction, beyond directly inhibiting NK cell function via RANK, may contribute to evasion of leukemia cells from NK immunosurveillance by creating an NK inhibitory cytokine milieu. This was revealed by impaired cytotoxicity and degranulation in response to leukemia targets following exposure of the NK cells to the factors released upon RANKL signaling by leukemia cells. Notably, the RANKL-mediated cytokine release of leukemia cells could be disrupted by the clinically approved RANKL antibody Denosumab/AMG162. Thus, RANKL signaling may trigger a “vicious cycle” comprising of release of immunosuppressive cytokines and also upregulation of RANK on NK cells. The latter both directly inhibits NK reactivity and may result in augmented RANKL signaling into leukemia cells. Our data suggest that therapeutic modulation of the RANK/RANKL system e.g. with Denosumab/AMG162, which is approved for treatment of osteolysis, may be a promising strategy to reinforce NK reactivity against hematopoietic malignancies. Disclosures: No relevant conflicts of interest to declare.

RANKL Expressed by Acute Myeloid Leukemia Cells Impairs NK Cell-Mediated Immune Surveillance

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2164-2164
Author(s):  
Benjamin J Schmiedel ◽  
Constantin M Wende ◽  
Tina Baessler ◽  
Carolin Scheible ◽  
Stefan Wirths ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Nk Cells ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Immune Surveillance ◽  
Surface Protein ◽  
Leukemia Cells ◽  
Acute Myeloid Leukemia Cells ◽  
Acute Myeloid

Abstract Abstract 2164 NK cells play an important role in tumor immunosurveillance, especially of leukemia. Their reactivity is governed by various activating and inhibitory molecules expressed by their targets including multiple members of the TNF family. The TNF family member Receptor Activator of NF-κB ligand (RANKL) and its receptors RANK and osteoprotegerin (OPG) are key regulators of bone remodelling, but recently have also been shown to influence progression of hematopoetic malignancies. Here we studied the yet unkown role of the RANK/RANKL molecule system in NK cells and their reactivity against acute myeloid leukemia (AML). Primary leukemia cells from AML patients were found to substantially express RANKL mRNA and surface protein in 75% of the investigated cases (n=40). Reverse signaling via surface-expressed RANKL into AML blasts induced the release of soluble factors including the immunoregulatory cytokines TNF and IL-10, which impaired NK cell anti-tumor reactivity. Moreover, we observed upregulation of RANK on NK cells among PBMC of healthy donors upon exposure to IL-10. This was not caused by direct effects on NK cells, but was rather due to yet unidentified factors released by monocytes among the PBMC upon IL-10 exposure and could be prevented by the activating cytokine IL-2. Furthermore, functional experiments with NK cells and RANKL transfectants or RANKL-negative controls revealed that forward signaling into RANK-expressing NK cells by tumor-expressed RANKL also directly impaired NK cytotoxicity and IFN-γ production. In line, blocking RANK-RANKL interaction using anti-RANKL antibodies or RANK-Fc fusion protein increased cytotoxicity and cytokine production of allogenic NK cells in cultures with RANKL-positive primary AML cells. Our data indicate that RANKL expression enables immune evasion of leukemia cells both by directly inhibiting reactivity of RANK-expressing NK cells and by orchestrating a reciprocal interplay between AML cells, monocytes and NK cells resulting in an immunosuppressive cytokine milieu. Thus, therapeutic modulation of the RANK/RANKL system, e.g. with Denosumab/AMG162, which is presently being evaluated for treatment of both non-malignant and malignant osteolysis, holds promise to reinforce NK reactivity against hematopoietic malignancies. Disclosures: No relevant conflicts of interest to declare.

Pseudoexpression of Glucocorticoid-Induced TNF-Related (GITR) Ligand Upon Coating of Cancer Cells by Platelets Impairs NK Cell Anti-Tumor Reactivity

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3193-3193 ◽  
Author(s):  
Theresa Placke ◽  
Lothar Kanz ◽  
Helmut R. Salih ◽  
Hans-Georg Kopp
Keyword(s):  
Nk Cells ◽  
Tumor Cells ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Immune Surveillance ◽  
Substantial Reduction ◽  
Cell Activity ◽  
Target Cells ◽  
Tumor Immune Escape ◽  
Tumor Spread

Abstract Abstract 3193 NK cells as part of the innate immune system substantially contribute to cancer immune surveillance. They prevent tumor progression and metastasis due to their ability to mediate cellular cytotoxicity and to produce cytokines like IFN-γ, which, among others, stimulates subsequent adaptive immune responses. NK reactivity results from an integrative response emerging upon recognition of multiple ligands for activating and inhibitory NK cell receptors including various members of the TNFR family. Apart from the direct interaction with their target cells, NK cell activity is further influenced by the reciprocal interplay with various other hematopoietic cells like e.g. dendritic cells. Metastatic tumor spread in experimental animals is dramatically reduced in thrombopenic mice. Additional depletion of NK cells reverses this effect, indicating that platelets may impair NK anti-tumor reactivity. However, the underlying mechanisms have not been fully elucidated, especially in humans. Recently, we demonstrated that NK anti-tumor immunity is impaired by platelet-derived TGF-β, which is released upon interaction of platelets with tumor cells (Kopp et al., Cancer Res. 2009). Here we report that the ligand for the TNFR family member GITR (GITRL) is upregulated on megakaryocytes during maturation resulting in substantial GITRL expression by platelets. Since we recently identified GITR as inhibitory NK receptor involved in tumor immune escape (e.g., Baltz et al., Blood 2008, Baessler et al., Cancer Res. 2009) we investigated how platelet-derived GITRL influences platelet function and NK immune surveillance. Signaling via GITRL into platelets upon interaction with NK-expressed GITR or recombinant GITR-Ig fusion protein did not alter platelet activation as revealed by analysis of the activation marker CD62P and release of TGF-β. Interestingly, we found that GITRL-negative tumor cells rapidly get coated by platelets, which confers a seemingly GITRL-positive phenotype. “GITRL pseudoexpression” on tumor cells caused a substantial reduction of NK cell cytotoxicity and cytokine production. This reduced NK reactivity was not due to induction of apoptosis via GITR and could be restored by addition of a blocking GITR antibody. Thus, coating of tumor cells by platelets inhibits NK reactivity, which is in part mediated by platelet-derived GITRL. Our data provide a functional basis for the previously observed finding that platelets increase metastasis i.e. by enabling evasion of tumor cells from NK-mediated immune surveillance. Disclosures: No relevant conflicts of interest to declare.

Fc-Engineered NKG2D-IgG1 Fusion Proteins Target Leukemia Cells for Antibody-Dependent Cellular Cytotoxicity (ADCC) of NK Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1537-1537 ◽  
Author(s):  
Julia Hilpert ◽  
Katrin Baltz-Ghahremanpour ◽  
Benjamin J Schmiedel ◽  
Lothar Kanz ◽  
Gundram Jung ◽  
...  
Keyword(s):  
Nk Cells ◽  
Fusion Proteins ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Leukemia Cell ◽  
Leukemic Cells ◽  
Leukemia Cells ◽  
Target Cells ◽  
Cellular Cytotoxicity ◽  
Antibody Dependent Cellular Cytotoxicity

Abstract Abstract 1537 The capability of anti-tumor antibodies to recruit Fc-receptor (FcR) bearing effector cells like NK cells, a feature considered critical for therapeutic success, can be markedly improved by modifications of the human IgG1 part. At present, Fc-engineered antibodies targeting leukemia cells are yet not available. The various ligands of the NK cell-activating immunoreceptor NKG2D (NKG2DL) are generally absent on healthy cells but upregulated on malignant cells of various origins including leukemia. We aimed to take advantage of the tumor-restricted expression of NKG2DL by using them as target-antigens for Fc-optimized NKG2D-IgG1 fusion proteins targeting leukemia cells for antibody-dependent cellular cytotoxicity (ADCC) and IFN-g production of NK cells. NKG2D-IgG1 fusion proteins with distinct modifications in their Fc portion were generated as previously described (Lazar 2006; Armour 1999). Compared to wildtype NKG2D-Fc (NKG2D-Fc-WT), the mutants (S239D/I332E and E233P/L234V/L235A/DG236/A327G/A330S) displayed highly enhanced (NKG2D-Fc-ADCC) and abrogated (NKG2D-Fc-KO) affinity to the NK cell FcgRIIIa receptor but comparable binding to NKG2DL-expressing target cells. Functional analyses with allogenic NK cells and leukemia cell lines as well as primary leukemic cells of AML and CLL patients revealed that NKG2D-Fc-KO significantly (p<0.05, Mann-Whitney U test) reduced NK cytotoxicity and IFN-g production (about 20% and 30% reduction, respectively), which can be attributed to blockade of NKG2DL-mediated activating signals. Treatment with NKG2D-Fc-WT significantly (p<0.05, Mann-Whitney U test) enhanced NK reactivity (about 20% and 100% increase in cytotoxicity and cytokine production, respectively). The effects observed upon treatment with NKG2D-Fc-ADCC by far exceeded that of NKG2D-Fc-WT resulting in at least doubled NK ADCC and IFN-g production compared to NKG2D-Fc-WT. When applied in combination with Rituximab in analyses with CLL cells, a clear additive effect resulting in a more than four-fold increase of ADCC and FcgRIIIa-induced IFN-g production was observed. The NKG2D-Fc fusion proteins did not induce NK reactivity against healthy blood cells, which is in line with the tumor-restricted expression of NKG2DL. Of note, treatment with NKG2D-Fc-ADCC also significantly (p<0.05, Mann-Whitney U test) enhanced reactivity (up to 70% increase) of NK cells against NKG2DL-positive AML and CLL cells among patient PBMC in an autologous setting. Together, our results demonstrate that Fc-engineered NKG2D-Fc-ADCC fusion proteins can effectively target NKG2DL-expressing leukemia cells for NK anti-tumor reactivity. In line with the hierarchically organized potential of the various activating receptors governing NK reactivity and due to their highly increased affinity to the FcgRIIIa receptor, NKG2D-Fc-ADCC potently enhances NK anti-leukemia reactivity despite the inevitable reduction of activating signals upon binding to NKG2DL. Due to the tumor-restricted expression of NKG2DL, Fc-modified NKG2D-Ig may thus constitute an attractive means for immunotherapy of leukemia. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Platelet-Derived Proteases ADAM10 and ADAM17 Impair NK Cell Immunosurveillance of Metastasizing Tumor Cells By Diminishing NKG2D Ligand Surface Expression

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4164-4164
Author(s):  
Stefanie Raab ◽  
Korbinian Nepomuk Kropp ◽  
Alexander Steinle ◽  
Gerd Klein ◽  
Lothar Kanz ◽  
...  
Keyword(s):  
Nk Cells ◽  
Tumor Cells ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Immune Surveillance ◽  
Surface Expression ◽  
Cytotoxic Lymphocytes ◽  
Platelet Surface ◽  
Tumor Immune Evasion ◽  
Platelet Releasate

Abstract Introduction: NK cells are cytotoxic lymphocytes the reactivity of which is governed by the principles of ‘missing-self’ and “induced-self’ recognition. This implies that cells with low or absent expression of MHC class I and/or stress-induced expression of ligands for activating receptors like NKG2D (NKG2DL) are preferentially eliminated by NK cells. We and others reported previously that NKG2DL undergo proteolytic cleavage (i.e. shedding) which promotes evasion from NKG2D-mediated tumor immunosurveillance. Notably, the reactivity of NK cells is also influenced by various other components of the hematopoietic system, and we and others provided evidence for the involvement of platelets in tumor immune evasion including impairment of NKG2D-mediated immune surveillance (e.g., Kopp et al., Cancer Res 2009, Raab et al., Blood 2013 122:3488). Here we extend our recent findings and provide further data how platelets affect immunostimulatory NKG2D-NKG2DL interaction. Methods: Tumor cells were incubated with platelets from healthy donors or treated with platelet-derived soluble factors (releasate) obtained by stimulation of platelets with known platelet agonists including ADP and thrombin. NKG2DL and ADAM10 as well as ADAM17 surface expression on tumor cells and platelets, respectively, was measured by FACS, while release of NKG2DL was determined by ELISA. ADAM10 and 17 protein levels were assessed by immunoblotting. NK cell lysis of tumor cells in the presence or absence of coating platelets or platelet releasate was determined by chromium release assays. Results: We found that interaction of platelets with tumor cells resulted in substantially reduced NKG2DL expression on the surface of the malignant cells, which was paralleled by enhanced release of soluble NKG2DL. Similar albeit weaker effects were observed upon treatment of tumor cells with platelet releasate, indicating that platelet-derived factors mediate NKG2DL shedding from the tumor cell surface. Notably, ADAM10 and ADAM17, the known sheddases of NKG2DL, were found to be expressed on the platelet surface, and sheddases could also be detected in platelet releasate, pointing to an involvement in platelet-mediated NKG2DL shedding. Diminished NKG2DL surface expression resulted in reduced NKG2D-mediated NK cell cytotoxicity as revealed by blocking experiments using NKG2D antibody and F(ab)2 fragments specific for the modulated NKG2DL. Conclusion: We propose that induction of NKG2DL shedding constitutes a novel mechanism by which the interaction of platelets with metastasizing tumor cells impairs NK cell immunosurveillance. Disclosures No relevant conflicts of interest to declare.

The FLT3-Inhibitors Midostaurin, Sunitinib, Sorafenib, and TKI258 Differentially Affect NK Cell-Mediated Immunesurveillance of Acute Myeloid Leukemia.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3785-3785
Author(s):  
Julia Salih ◽  
Lothar Kanz ◽  
Helmut R Salih ◽  
Matthias Krusch
Keyword(s):  
Nk Cells ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Immune Surveillance ◽  
Leukemia Cells ◽  
Target Cells ◽  
Cell Reactivity ◽  
Flt3 Inhibitors ◽  
Ifn Γ

Abstract Abstract 3785 Poster Board III-721 FLT3 is a receptor tyrosine kinase with an important role in hematopoietic progenitor cell survival and proliferation. The discovery of internal tandem duplication mutations (ITD) in FLT3 was a major breakthrough in understanding the role of abnormally activated FLT3 in myeloid transformation. Between 15% and 34% of AML patients show FLT3-ITD mutations, and thus the inhibition of FLT3 in combination with chemotherapeutic agents may be a promising stragety in the treatment of Acute Myeloid Leukemia (AML). Several protein kinase inhibitors (PKI) targeting FLT3 like e.g. Midostaurin, Sunitinib, Sorafenib, and TKI258 are currently under preclinical and/or clinical evaluation (http://clinicaltrials.gov/ct2/results?term=AML+and+FLT3). Since those PKI, besides targeting their eponymous enzyme FLT3, also inhibit signaling via other molecules they may impair the effector function of various components of anti-tumor immunity. NK cells as part of the innate immune system play an important role in the immune surveillance of tumors due to their ability to directly kill target cells and to shape adaptive immune responses by secreting cytokines like IFN-γ. Clinical evidence for the particularly important role of NK cells in leukemia has recently been provided by studies of haploidentical stem cell transplantation (Ruggeri et al., Science 2002). We report here that CD107a expression as a surrogate marker for degranulation of NK cells within PBMC is inhibited by pharmacological concentrations of Sorafenib (10μg/ml) and Midostaurin (2μg/ml), but not by Sunitinib (200ng/ml) and TKI258 (125ng/ml). In line, pharmacological concentrations of Sunitinib and TKI258 did not affect NK cell cytotoxicity and IFN-γ production in cocultures with leukemia cells. Sorafenib and Midostaurin caused a clear concentration-dependent inhibition of NK cell cytokine production in response to target cells both in resting and in IL-2 activated state (92% and 66%, respectively at plasma peak levels). Furthermore, pharmacological concentrations of Sorafenib and Midostaurin also reduced lysis of leukemia cells by NK cells (54% and 58%, respectively, E:T ratio 10:1) and thus generally compromised NK cell reactivity. Analysis of NK cell signaling revealed that Sorafenib, but not Midostaurin decreased phosphorylation of PI3K and ERK which are important regulators of NK cell reactivity. Thus, Midostaurin inhibits yet undefined signaling events which are crucial for NK effector functions, but are independent of the “classical” PI3K – Rac – PAK – MEK – ERK pathway and are presently under study. Moreover, in light of the important role of NK cells in the immune surveillance of leukemia and the differential influence of clinically used FLT3-inhibitors on NK cell functions our data indicate that the choice and dosing of the most suitable compound in the treatment of AML requires further characterization and careful consideration. Disclosures: No relevant conflicts of interest to declare.

Costimulatory Effects of Interleukin-18 (IL-18) on Human Natural Killer (NK) Cells Activated through Fc Receptors for Immunoglobulin (IgG)

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2780-2780
Author(s):  
Shivani Srivastava ◽  
Hailin Feng ◽  
Menggang Yu ◽  
David Pelloso ◽  
Michael Robertson
Keyword(s):  
Monoclonal Antibodies ◽  
Nk Cells ◽  
Cell Function ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Fc Receptors ◽  
Cytolytic Activity ◽  
Mitogen Activated Protein Kinase ◽  
Target Cells

Abstract Abstract 2780 NK cells play an important role in innate and adaptive immune responses. Most human NK cells express CD16, an Fc receptor for IgG that mediates lysis of antibody-coated target cells and costimulates interferon (IFN)-g production in response to cytokines. IL-18 is an immunostimulatory cytokine with antitumor activity in preclinical animal models. The effects of IL-18 on human NK cell function were examined. Here we show that NK cells stimulated with immobilized IgG in vitro secreted IFN-g; such IFN-g production was partially inhibited by blocking CD16 with monoclonal antibodies. IL-18 augmented IFN-g production by NK cells stimulated with immobilized IgG or CD16 antibodies (Figure 1). NK cell IFN-g production in response to immobilized IgG and/or IL-18 was inhibited by chemical inhibitors of Syk, extracellular signal-related kinases (ERK), p38 mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI3-K). Stimulation with IL-18 or immobilized IgG could augment IL-12-induced IFN-g production by STAT4-deficient lymphocytes obtained from lymphoma patients after autologous stem cell transplantation (Figure 2). IL-18 also augmented the in vitro lysis of rituximab-coated Raji cells by human NK cells (Figure 3). These observations that IL-18 can co stimulate IFN-g production and cytolytic activity of NK cells activated through Fc receptors makes it an attractive cytokine to combine with monoclonal antibodies for treatment of cancer. Disclosure: No relevant conflicts of interest to declare.

Resveratrol Enhances NKG2D-Mediated Cytotoxicity Against Leukemia Cells by Upregulating Both NKG2D Receptor on NK Cells As Well As NKG2D Ligands on Target Cells,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3236-3236
Author(s):  
Luis J. Espinoza ◽  
Akiyoshi Takami ◽  
Katsuya Nakata ◽  
Ly Quoc Trung ◽  
Kayoko Yamada ◽  
...  
Keyword(s):  
Nk Cells ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Specific Inhibitor ◽  
Receptor Expression ◽  
Leukemia Cells ◽  
Target Cells ◽  
Lymphoid Leukemia ◽  
Nkg2d Ligands ◽  
Nkg2d Receptor

Abstract Abstract 3236 NKG2D is a powerful activating receptor expressed by natural killer (NK) cells that promotes cytotoxic lysis of cancer cells expressing NKG2D ligands (NKG2D-Ls). Pharmacological induction of NKG2D-Ls in malignant cells has been an attractive therapeutic approach but has gained poor clinical utility because currently available NKG2D-Ls inducers have been hampered either by their limited efficacy or by their associated toxicity. Resveratrol (RVT), a compound derived from several natural sources, has proved in vivo and in vitro potent anti-tumor effects against various cancers. Extensive research in the last decade has shown that such effects are mediated by targeting various molecules involved in the regulation of proliferation and cell survival and those include, NFκB, STAT3, ATM/ATR and ERK1/2. To date, it is unknown whether RVT has any effect on NKG2D-Ls expression. We report here NKG2D-Ls induction by RVT in a broad range of leukemia cells. RVT upregulated the NKG2D-Ls MICA/B, ULBP1, ULBP2 and ULBP3 in the myeloid leukemia cells OUN-1, NB4, THP-1 and KG1 and upregulated MICA/B, ULBP-1 and ULBP3 ligands in the lymphoid leukemia cells Jurkat and Molt-4. The upregulation of NKG2D-Ls by RVT was associated with increased transcription of each NKG2D-L gene. Ligand upregulation induced by RVT was prevented by cell pretreatment with caffeine, and inhibitor of ATM/ATR, which is the main signal regulator of NKG2D-Ls expression. Leukemia cells treated with RVT were more susceptible to killing by NK cells than untreated cells and the enhanced cytotoxicity of NK cells was blocked by the treatment of NK cells with anti-NKG2D monoclonal antibodies. Interestingly, the same concentration of RVT that effectively induced NKG2D-Ls in tumor cells, consistently upregulated NKG2D receptor expression in primary NK cells from healthy individuals and in the NK cell lines NKL and NK-92 and this effect was also associated with enhanced NKG2D-mediated NK cells cytotoxicity. RVT-induced NKG2D receptor enhancement in NK cells associated with the activation of the MAP kinase ERK1/2 and was prevented by the ERK1/2 specific inhibitor PD98059. Thus, RVT represents the first identified agent capable of activating both arms of the NKG2D axis. Since several clinical trials on RVT are ongoing, these previously unrecognized properties of this non toxic compound have an attractive immunotherapeutic potential. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Sialic Acids and Their Influence on Human NK Cell Function

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 263
Author(s):  
Philip Rosenstock ◽  
Thomas Kaufmann
Keyword(s):  
Nk Cells ◽  
Immune Cells ◽  
Cell Function ◽  
Nk Cell ◽  
Sialic Acids ◽  
Innate Immune ◽  
Target Cells ◽  
Carbon Backbone ◽  
Nk Cell Receptors ◽  
Cell Inhibition

Sialic acids are sugars with a nine-carbon backbone, present on the surface of all cells in humans, including immune cells and their target cells, with various functions. Natural Killer (NK) cells are cells of the innate immune system, capable of killing virus-infected and tumor cells. Sialic acids can influence the interaction of NK cells with potential targets in several ways. Different NK cell receptors can bind sialic acids, leading to NK cell inhibition or activation. Moreover, NK cells have sialic acids on their surface, which can regulate receptor abundance and activity. This review is focused on how sialic acids on NK cells and their target cells are involved in NK cell function.

scholarly journals The Ly-49D Receptor Activates Murine Natural Killer Cells

1996 ◽  
Vol 184 (6) ◽  
pp. 2119-2128 ◽  
Author(s):  
L.H. Mason ◽  
S.K. Anderson ◽  
W.M. Yokoyama ◽  
H.R.C. Smith ◽  
R. Winkler-Pickett ◽  
...  
Keyword(s):  
Gene Family ◽  
Nk Cells ◽  
Natural Killer ◽  
Cell Function ◽  
Nk Cell ◽  
Cell Subset ◽  
Class I ◽  
Target Cells ◽  
Color Flow ◽  
Functional Capabilities

Proteins encoded by members of the Ly-49 gene family are predominantly expressed on murine natural killer (NK) cells. Several members of this gene family have been demonstrated to inhibit NK cell lysis upon recognizing their class I ligands on target cells. In this report, we present data supporting that not all Ly-49 proteins inhibit NK cell function. Our laboratory has generated and characterized a monoclonal antibody (mAb) (12A8) that can be used to recognize the Ly-49D subset of murine NK cells. Transfection of Cos-7 cells with known members of the Ly-49 gene family revealed that 12A8 recognizes Ly-49D, but also cross-reacts with the Ly-49A protein on B6 NK cells. In addition, 12A8 demonstrates reactivity by both immunoprecipitation and two-color flow cytometry analysis with an NK cell subset that is distinct from those expressing Ly-49A, C, or G2. An Ly-49D+ subset of NK cells that did not express Ly49A, C, and G2 was isolated and examined for their functional capabilities. Tumor targets and concanovalin A (ConA) lymphoblasts from a variety of H2 haplotypes were examined for their susceptibility to lysis by Ly-49D+ NK cells. None of the major histocompatibility complex class I–bearing targets inhibited lysis of Ly-49D+ NK cells. More importantly, we demonstrate that the addition of mAb 12A8 to Ly-49D+ NK cells can augment lysis of FcγR+ target cells in a reverse antibody-dependent cellular cytotoxicity–type assay and induces apoptosis in Ly49D+ NK cells. Furthermore, the cytoplasmic domain of Ly-49D does not contain the V/IxYxxL immunoreceptor tyrosine-based inhibitory motif found in Ly-49A, C, or G2 that has been characterized in the human p58 killer inhibitory receptors. Therefore, Ly-49D is the first member of the Ly-49 family characterized as transmitting positive signals to NK cells, rather than inhibiting NK cell function.

scholarly journals CD38 deletion of human primary NK cells eliminates daratumumab-induced fratricide and boosts their effector activity

Blood ◽  
2020 ◽  
Vol 136 (21) ◽  
pp. 2416-2427 ◽  
Author(s):  
Meisam Naeimi Kararoudi ◽  
Yuya Nagai ◽  
Ezgi Elmas ◽  
Marcelo de Souza Fernandes Pereira ◽  
Syed Abbas Ali ◽  
...  
Keyword(s):  
Nk Cells ◽  
Cell Function ◽  
Nk Cell ◽  
Ex Vivo ◽  
Human Monoclonal Antibody ◽  
Metabolic Reprogramming ◽  
Target Cells ◽  
Plasma Cell Neoplasm ◽  
Cd38 Expression ◽  
The Impact

Abstract Multiple myeloma (MM) is a plasma cell neoplasm that commonly expresses CD38. Daratumumab (DARA), a human monoclonal antibody targeting CD38, has significantly improved the outcome of patients with relapsed or refractory MM, but the response is transient in most cases. Putative mechanisms of suboptimal efficacy of DARA include downregulation of CD38 expression and overexpression of complement inhibitory proteins on MM target cells as well as DARA-induced depletion of CD38high natural killer (NK) cells resulting in crippled antibody-dependent cellular cytotoxicity (ADCC). Here, we tested whether maintaining NK cell function during DARA therapy could maximize DARA-mediated ADCC against MM cells and deepen the response. We used the CRISPR/Cas9 system to delete CD38 (CD38KO) in ex vivo expanded peripheral blood NK cells. These CD38KO NK cells were completely resistant to DARA-induced fratricide, showed superior persistence in immune-deficient mice pretreated with DARA, and enhanced ADCC activity against CD38-expressing MM cell lines and primary MM cells. In addition, transcriptomic and cellular metabolic analysis demonstrated that CD38KO NK cells have unique metabolic reprogramming with higher mitochondrial respiratory capacity. Finally, we evaluated the impact of exposure to all-trans retinoic acid (ATRA) on wild-type NK and CD38KO NK cell function and highlighted potential benefits and drawbacks of combining ATRA with DARA in patients with MM. Taken together, these findings provide proof of concept that adoptive immunotherapy using ex vivo expanded CD38KO NK cells has the potential to boost DARA activity in MM.

Sign in / Sign up

Export Citation Format

Share Document