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Elotuzumab enhances natural killer cell activation and myeloma cell killing through interleukin-2 and TNF-α pathways. Cancer Immunol Immunother 2014; 64:61-73. [PMID: 25287778 PMCID: PMC4282702 DOI: 10.1007/s00262-014-1610-3] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 09/12/2014] [Indexed: 01/22/2023]
Abstract
Elotuzumab is a humanized monoclonal antibody specific for signaling lymphocytic activation molecule-F7 (SLAMF7, also known as CS1, CD319, or CRACC) that enhances natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC) of SLAMF7-expressing myeloma cells. This study explored the mechanisms underlying enhanced myeloma cell killing with elotuzumab as a single agent and in combination with lenalidomide, to support ongoing phase III trials in patients with relapsed/refractory or newly-diagnosed multiple myeloma (MM). An in vitro peripheral blood lymphocyte (PBL)/myeloma cell co-culture model was developed to evaluate the combination of elotuzumab and lenalidomide. Expression of activation markers and adhesion receptors was evaluated by flow cytometry, cytokine expression by Luminex and ELISPOT assays, and cytotoxicity by myeloma cell counts. Elotuzumab activated NK cells and promoted myeloma cell death in PBL/myeloma cell co-cultures. The combination of elotuzumab plus lenalidomide demonstrated superior anti-myeloma activity on established MM xenografts in vivo and in PBL/myeloma cell co-cultures in vitro than either agent alone. The combination enhanced myeloma cell killing by modulating NK cell function that coincided with the upregulation of adhesion and activation markers, including interleukin (IL)-2Rα expression, IL-2 production by CD3+CD56+ lymphocytes, and tumor necrosis factor (TNF)-α production. In co-culture assays, TNF-α directly increased NK cell activation and myeloma cell death with elotuzumab or elotuzumab plus lenalidomide, and neutralizing TNF-α decreased NK cell activation and myeloma cell death with elotuzumab. These results demonstrate that elotuzumab activates NK cells and induces myeloma cell death via NK cell-mediated ADCC, which is further enhanced when combined with lenalidomide.
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Khaznadar Z, Henry G, Setterblad N, Agaugue S, Raffoux E, Boissel N, Dombret H, Toubert A, Dulphy N. Acute myeloid leukemia impairs natural killer cells through the formation of a deficient cytotoxic immunological synapse. Eur J Immunol 2014; 44:3068-80. [PMID: 25041786 DOI: 10.1002/eji.201444500] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 06/30/2014] [Accepted: 07/10/2014] [Indexed: 11/08/2022]
Abstract
Acute myeloid leukemia (AML) cells are killed by allogeneic NK cells. However, autologous NK cells from AML patients express decreased levels of activating receptors, and show reduced cytotoxicity. Here, we investigated how interactions between NK and AML cells might cause loss of NK-cell activity in patients. Our results show that AML cell lines and primary blasts alter the NK-cell phenotype, reducing their cytotoxic potential upon prolonged contact. Downregulation of NK-cell-activating receptors was contact-dependent and correlated with conjugate formation. Time-lapse imaging of HL60 AML cell line and NK-cell interactions showed a high proportion of noncytolytic contacts. Studies of NK-cell immunological synapses revealed a defect in lytic synapse formation. Namely, despite correct F-actin and LFA-1 recruitment, polarization of lytic granules toward primary blasts or AML cell lines was reduced. The NK-AML cell line synapses showed impairment of CD3ζ recruitment. Attempts to correct these synapse defects by cytokine stimulation of NK cells improved conjugate formation, but not granule polarization. Pretreatment of AML cell lines with the immunomodulating molecule lenalidomide significantly enhanced granule polarization. We speculate that combining immunomodulatory drugs and cytokines could increase AML cell sensitivity to autologous NK cells and reinforce the activity of allogeneic NK cells in adoptive immunotherapy.
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Affiliation(s)
- Zena Khaznadar
- Institut National de la Santé et de la Recherche Médicale (INSERM UMRS 1160), Paris, France; Institut Universitaire d'Hématologie, Univ Paris Diderot, Paris, France
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53
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Lagrue K, Carisey A, Oszmiana A, Kennedy PR, Williamson DJ, Cartwright A, Barthen C, Davis DM. The central role of the cytoskeleton in mechanisms and functions of the NK cell immune synapse. Immunol Rev 2014; 256:203-21. [PMID: 24117823 DOI: 10.1111/imr.12107] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Natural killer (NK) cells discriminate between healthy and unhealthy target cells through a balance of activating and inhibitory signals at direct intercellular contacts called immune synapses. Rearrangements in the cellular cytoskeleton have long been known to be critical in assembly of immune synapses. Here, through bringing together the vast literature on this subject, the number of different ways in which the cytoskeleton is important becomes evident. The dynamics of filamentous actin are critical in (i) creating the nanometer-scale organization of NK cell receptors, (ii) establishing cellular polarity, (iii) coordinating immune receptor and integrin-mediated signaling, and (iv) directing secretion of lytic granules and cytokines. The microtubule network also is important in the delivery of lytic granules and vesicles containing cytokines to the immune synapse. Together, these data establish that the cytoskeleton acts as a central regulator of this complex and dynamic process - and an enormous amount of NK cell biology is controlled through the cytoskeleton.
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Affiliation(s)
- Kathryn Lagrue
- Manchester Collaborative Centre for Inflammation Research, University of Manchester, Manchester, UK; Division of Cell and Molecular Biology, Imperial College, London, UK
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54
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Kuehn C, Vermette P, Fülöp T. Cross talk between the extracellular matrix and the immune system in the context of endocrine pancreatic islet transplantation. A review article. ACTA ACUST UNITED AC 2014; 62:67-78. [DOI: 10.1016/j.patbio.2014.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 01/31/2014] [Indexed: 12/14/2022]
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Mace EM, Dongre P, Hsu HT, Sinha P, James AM, Mann SS, Forbes LR, Watkin LB, Orange JS. Cell biological steps and checkpoints in accessing NK cell cytotoxicity. Immunol Cell Biol 2014; 92:245-55. [PMID: 24445602 PMCID: PMC3960583 DOI: 10.1038/icb.2013.96] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 11/06/2013] [Indexed: 12/11/2022]
Abstract
Natural killer (NK) cell-mediated cytotoxicity is governed by the formation of a lytic immune synapse in discrete regulated steps, which give rise to an extensive array of cellular checkpoints in accessing NK cell-mediated cytolytic defense. Appropriate progression through these cell biological steps is critical for the directed secretion of specialized secretory lysosomes and subsequent target cell death. Here we highlight recent discoveries in the formation of the NK cell cytolytic synapse as well as the molecular steps and cell biological checkpoints required for this essential host defense process.
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Affiliation(s)
- Emily M Mace
- Center for Human Immunobiology, Baylor College of Medicine and Texas Children's Hospital, Houston, TX, USA
| | - Prachi Dongre
- Center for Human Immunobiology, Baylor College of Medicine and Texas Children's Hospital, Houston, TX, USA
| | - Hsiang-Ting Hsu
- Center for Human Immunobiology, Baylor College of Medicine and Texas Children's Hospital, Houston, TX, USA
| | - Papiya Sinha
- Center for Human Immunobiology, Baylor College of Medicine and Texas Children's Hospital, Houston, TX, USA
| | | | - Shaina S Mann
- Case Western Reserve Medical School, Cleveland, OH, USA
| | - Lisa R Forbes
- Center for Human Immunobiology, Baylor College of Medicine and Texas Children's Hospital, Houston, TX, USA
| | - Levi B Watkin
- Center for Human Immunobiology, Baylor College of Medicine and Texas Children's Hospital, Houston, TX, USA
| | - Jordan S Orange
- Center for Human Immunobiology, Baylor College of Medicine and Texas Children's Hospital, Houston, TX, USA
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56
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MiRNA-296-3p-ICAM-1 axis promotes metastasis of prostate cancer by possible enhancing survival of natural killer cell-resistant circulating tumour cells. Cell Death Dis 2013; 4:e928. [PMID: 24263102 PMCID: PMC3847334 DOI: 10.1038/cddis.2013.458] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 10/06/2013] [Accepted: 10/21/2013] [Indexed: 01/28/2023]
Abstract
Natural killer (NK) cells are important in host to eliminate circulating tumour cells (CTCs) in turn preventing the development of tumour cells into metastasis but the mechanisms are very poorly defined. Here we find that the expression level of miR-296-3p is much lower in the non-metastatic human prostate cancer (PCa) cell line P69 than that in the highly metastatic cell line M12, which is derived from P69. We demonstrate that miR-296-3p directly targets and inhibits the expression of intercellular adhesion molecule 1 (ICAM-1) in the malignant M12. The data from clinical tissue microarrays also show that miR-296-3p is frequently upregulated and ICAM-1 is reversely downregulated in PCa. Interestingly, ectopic expression of miR-296-3p in P69 increases the tolerance to NK cells whereas knockdown of miR-296-3p in M12 reduces the resistance to NK cells, which both phenotypes can be rescued by re-expression or silencing of ICAM-1 in P69 and M12, respectively. These results are also manifested in vivo by the decrease in the incidence of pulmonary tumour metastasis exhibited by knockdown of miR-296-3p in M12 when injected into athymic nude mice via tail vein, and consistently down-expression of ICAM-1 reverses this to increase extravasation of CTCs into lungs. Above results suggest that this newly identified miR-296-3p-ICAM-1 axis has a pivotal role in mediating PCa metastasis by possible enhancing survival of NK cell-resistant CTC. Our findings provide novel potential targets for PCa therapy and prognosis.
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57
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Natural killer cell biology: an update and future directions. J Allergy Clin Immunol 2013; 132:536-544. [PMID: 23906377 DOI: 10.1016/j.jaci.2013.07.006] [Citation(s) in RCA: 274] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 07/08/2013] [Accepted: 07/11/2013] [Indexed: 12/11/2022]
Abstract
Natural killer (NK) cells constitute a minor subset of normal lymphocytes that initiate innate immune responses toward tumor and virus-infected cells. They can mediate spontaneous cytotoxicity toward these abnormal cells and rapidly secrete numerous cytokines and chemokines to promote subsequent adaptive immune responses. Significant progress has been made in the past 2 decades to improve our understanding of NK cell biology. Here we review recent discoveries, including a better comprehension of the "education" of NK cells to achieve functional competence during their maturation and the discovery of "memory" responses by NK cells, suggesting that they might also contribute to adaptive immunity. The improved understanding of NK cell biology has forged greater awareness that these cells play integral early roles in immune responses. In addition, several promising clinical therapies have been used to exploit NK cell functions in treating patients with cancer. As our molecular understanding improves, these and future immunotherapies should continue to provide promising strategies to exploit the unique functions of NK cells to treat cancer, infections, and other pathologic conditions.
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58
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Yin S, Zhang J, Mao Y, Hu Y, Cui L, Kang N, He W. Vav1-phospholipase C-γ1 (Vav1-PLC-γ1) pathway initiated by T cell antigen receptor (TCRγδ) activation is required to overcome inhibition by ubiquitin ligase Cbl-b during γδT cell cytotoxicity. J Biol Chem 2013; 288:26448-62. [PMID: 23897818 DOI: 10.1074/jbc.m113.484600] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
T cell antigen receptor γδ (TCRγδ) and natural killer group 2, member D (NKG2D) are two crucial receptors for γδT cell cytotoxicity. Compelling evidences suggest that γδT cell cytotoxicity is TCRγδ-dependent and can be co-stimulated by NKG2D. However, the molecular mechanism of underlying TCRγδ-dependent activation of γδT cells remains unclear. In this study we demonstrated that TCRγδ but not NKG2D engagement induced lytic granule polarization and promoted γδT cell cytotoxicity. TCRγδ activation alone was sufficient to trigger Vav1-dependent phospholipase C-γ1 signaling, resulting in lytic granule polarization and effective killing, whereas NKG2D engagement alone failed to trigger cytotoxicity-related signaling to overcome the inhibitory effect of Cbl-b; therefore, NKG2D engagement alone could not induce effective killing. However, NKG2D ligation augmented the activation of γδT cell cytotoxicity through the Vav1-phospholipase C-γ1 pathway. Vav1 overexpression or Cbl-b knockdown not only enhanced TCRγδ activation-initiated killing but also enabled NKG2D activation alone to induce γδT cell cytotoxicity. Taken together, our results suggest that the activation of γδT cell cytotoxicity requires a strong activation signal to overcome the inhibitory effect of Cbl-b. Our finding provides new insights into the molecular mechanisms underlying the initiation of γδT cell cytotoxicity and likely implications for optimizing γδT cell-based cancer immunotherapy.
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Affiliation(s)
- Shanshan Yin
- From the Department of Immunology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Peking Union Medical College, National Key Laboratory of Medical Molecular Biology, Beijing 100005, China
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59
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Abstract
Integrins not only mediate cell-cell and cell-extracellular matrix adhesion, but also affect the multitude of signal transduction cascades in control of cell survival, proliferation, differentiation and organ development. Mutations in integrins or the major effectors of integrin signalling pathways cause defective organ development, immunodeficiency, cancer or autoimmune disease. Understanding of the signalling events that drive integrin activation and signalling is therefore crucial to uncover the molecular mechanisms of these diseases. This review discusses the key signalling complexes regulating integrin activation and function in both 'inside-out' and 'outside-in' pathways in T lymphocytes, including kinases, SLP-76, VAV1, ADAP, SKAP-55, RapL, RIAM, Rap1, Talin and Kindlin.
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Affiliation(s)
- Yanbo Zhang
- The State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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60
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Integrin inside-out signaling and the immunological synapse. Curr Opin Cell Biol 2011; 24:107-15. [PMID: 22129583 DOI: 10.1016/j.ceb.2011.10.004] [Citation(s) in RCA: 291] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 10/19/2011] [Indexed: 11/22/2022]
Abstract
Integrins dynamically equilibrate between three conformational states on cell surfaces. A bent conformation has a closed headpiece. Two extended conformations contain either a closed or an open headpiece. Headpiece opening involves hybrid domain swing-out and a 70 Å separation at the integrin knees, which is conveyed by allostery from the hybrid-proximal end of the βI domain to a 3 Å rearrangement of the ligand-binding site at the opposite end of the βI domain. Both bent-closed and extended-closed integrins have low affinity, whereas extended-open integrin affinity is 10(3) to 10(4) higher. Integrin-mediated adhesion requires the extended-open conformation, which in physiological contexts is stabilized by post-ligand binding events. Integrins thus discriminate between substrate-bound and soluble ligands. Analysis of LFA-1-ICAM-1 interactions in the immunological synapse suggests that bond lifetimes are on the order of seconds, which is consistent with high affinity interactions subjected to cytoskeletal forces that increase the dissociation rate. LFA-1 βI domain antagonists abrogate function in the immunological synapse, further supporting a critical role for high affinity LFA-1.
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61
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Schürpf T, Springer TA. Regulation of integrin affinity on cell surfaces. EMBO J 2011; 30:4712-27. [PMID: 21946563 DOI: 10.1038/emboj.2011.333] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 08/22/2011] [Indexed: 11/09/2022] Open
Abstract
Lymphocyte activation triggers adhesiveness of lymphocyte function-associated antigen-1 (LFA-1; integrin α(L)β(2)) for intercellular adhesion molecules (ICAMs) on endothelia or antigen-presenting cells. Whether the activation signal, after transmission through multiple domains to the ligand-binding αI domain, results in affinity changes for ligand has been hotly debated. Here, we present the first comprehensive measurements of LFA-1 affinities on T lymphocytes for ICAM-1 under a broad array of activating conditions. Only a modest increase in affinity for soluble ligand was detected after activation by chemokine or T-cell receptor ligation, conditions that primed LFA-1 and robustly induced lymphocyte adhesion to ICAM-1 substrates. By stabilizing well-defined LFA-1 conformations by Fab, we demonstrate the absolute requirement of the open LFA-1 headpiece for adhesiveness and high affinity. Interaction of primed LFA-1 with immobilized but not soluble ICAM-1 triggers energy-dependent affinity maturation of LFA-1 to an adhesive, high affinity state. Our results lend support to the traction or translational motion dependence of integrin activation.
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Affiliation(s)
- Thomas Schürpf
- Department of Pathology, Harvard Medical School, Immune Disease Institute and Children's Hospital, Boston, MA, USA
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62
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Dustin ML, Depoil D. New insights into the T cell synapse from single molecule techniques. Nat Rev Immunol 2011; 11:672-84. [PMID: 21904389 DOI: 10.1038/nri3066] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
T cell activation depends on extracellular ligation of the T cell receptor (TCR) by peptide-MHC complexes in a synapse between the T cell and an antigen-presenting cell. The process then requires the assembly of signalling complexes between the TCR and the adaptor protein linker for activation of T cells (LAT), and subsequent filamentous actin (F-actin)-dependent TCR cluster formation. Recent progress in each of these areas, made possible by the emergence of new techniques, has forced us to rethink our assumptions and consider some radical new models. These describe the receptor interaction parameters that control T cell responses and the mechanism by which LAT is recruited to the TCR signalling machinery. This is an exciting time in T cell biology, and further innovation in imaging and genomics is likely to lead to a greater understanding of how T cells are activated.
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Affiliation(s)
- Michael L Dustin
- Helene and Martin Kimmel Center for Biology and Medicine of the Skirball Institute of Biomolecular Medicine, Department of Pathology, New York University School of Medicine, 540 First Avenue, New York, New York 10012, USA.
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63
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Long EO. ICAM-1: getting a grip on leukocyte adhesion. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2011; 186:5021-3. [PMID: 21505213 PMCID: PMC3860744 DOI: 10.4049/jimmunol.1100646] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Eric O Long
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
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64
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Liu D, Martina JA, Wu XS, Hammer JA, Long EO. Two modes of lytic granule fusion during degranulation by natural killer cells. Immunol Cell Biol 2011; 89:728-38. [PMID: 21483445 PMCID: PMC3257049 DOI: 10.1038/icb.2010.167] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Lytic granules in cytotoxic lymphocytes, which include T cells and natural killer (NK) cells, are secretory lysosomes that release their content upon fusion with the plasma membrane (PM), a process known as degranulation. Although vesicle exocytosis has been extensively studied in endocrine and neuronal cells, much less is known about the fusion of lytic granules in cytotoxic lymphocytes. Here, we used total internal reflection fluorescence microscopy to examine lytic granules labeled with fluorescently tagged Fas ligand (FasL) in the NK cell line NKL stimulated with phorbol ester and ionomycin and in primary NK cells activated by physiological receptor–ligand interactions. Two fusion modes were observed: complete fusion, characterized by loss of granule content and rapid diffusion of FasL at the PM; and incomplete fusion, characterized by transient fusion pore opening and retention of FasL at the fusion site. The pH-sensitive green fluorescence protein (pHluorin) fused to the lumenal domain of FasL was used to visualize fusion pore opening with a time resolution of 30 ms. Upon incomplete fusion, pHluorin emission lasted several seconds in the absence of noticeable diffusion. Thus, we conclude that lytic granules in NK cells undergo both complete and incomplete fusion with the PM, and propose that incomplete fusion may promote efficient recycling of lytic granule membrane after the release of cytotoxic effector molecules.
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Affiliation(s)
- Dongfang Liu
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
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65
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Martinez E, Brzostowski JA, Long EO, Gross CC. Cutting edge: NKG2D-dependent cytotoxicity is controlled by ligand distribution in the target cell membrane. THE JOURNAL OF IMMUNOLOGY 2011; 186:5538-42. [PMID: 21464092 DOI: 10.4049/jimmunol.1002254] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Although the importance of membrane microdomains in receptor-mediated activation of lymphocytes has been established, much less is known about the role of receptor ligand distribution on APC and target cells. Detergent-resistant membrane domains, into which GPI-linked proteins partition, are enriched in cholesterol and glycosphingolipids. ULBP1 is a GPI-linked ligand for natural cytotoxicity receptor NKG2D. To investigate how ULBP1 distribution on target cells affects NKG2D-dependent NK cell activation, we fused the extracellular domain of ULBP1 to the transmembrane domain of CD45. Introduction of this transmembrane domain eliminated the association of ULBP1 with the detergent-resistant membrane fraction and caused a significant reduction of cytotoxicity and degranulation by NK cells. Clustering and lateral diffusion of ULBP1 was not affected by changes in the membrane anchor. These results show that the partitioning of receptor ligands in discrete membrane domains of target cells is an important determinant of NK cell activation.
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Affiliation(s)
- Emily Martinez
- Molecular and Cellular Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
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66
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Guilmot A, Hermann E, Braud VM, Carlier Y, Truyens C. Natural killer cell responses to infections in early life. J Innate Immun 2011; 3:280-8. [PMID: 21411972 DOI: 10.1159/000323934] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Accepted: 12/24/2010] [Indexed: 12/12/2022] Open
Abstract
Natural killer (NK) cells are an important component of innate immune responses to infectious diseases. They mediate protection by being able to rapidly lyse infected cells and produce cytokines (primarily interferon-γ) that shape innate and adaptive immune responses. This review summarizes current knowledge on the phenotype and functional abilities of NK cells from healthy newborns/infants and on NK cell responses against viral, bacterial and protozoan infections in early life. Interestingly, NK cell blood counts are higher in newborns than in adults but they do not display striking differences in phenotype, except for an increased frequency of expression of the inhibitory CD94/NKG2A receptor. They display some inherent functional defects, mainly a lower cytolytic capacity that may contribute to the immaturity of the neonatal immune system. Changes in circulating levels of NK cells observed during pediatric infections and the ability of NK cells from newborns and children to produce interferon-γ at the encounter with pathogens indicate that NK cells participate in the immune response to infectious diseases in early life. Unfortunately, information is currently insufficient to assess whether these NK cell responses really contribute to control infections, either vertically transmitted or acquired in infancy.
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Affiliation(s)
- Aline Guilmot
- Laboratoire de Parasitologie, Faculté de Médecine, Université Libre de Bruxelles, Brussels, Belgium
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