Immunoregulatory role of CD1d in the hydrocarbon oil-induced model of lupus nephritis

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that is accompanied by the emergence of autoreactive T cells and a reduction in regulatory T cells. Humans and mice with SLE have reduced numbers of CD1d-restricted NK T cells, suggesting a role for these cells in the regulation of SLE. In this study, we show that CD1d deficiency exacerbates lupus nephritis induced by the hydrocarbon oil pristane. This exacerbation in disease is associated with: 1) reduced TNF-alpha and IL-4 production by T cells, especially during the disease induction phase; and 2) expansion of marginal zone B cells. Strikingly, inoculation of pristane in wild-type mice resulted in reduced numbers and/or functions of NK T cells and CD1d-expressing dendritic cells. These findings suggest that CD1d may play an immunoregulatory role in the development of lupus in the pristane-induced model.     

IL-21 promotes lupus-like disease in chronic graft-versus-host disease through both CD4 T cell- and B cell-intrinsic mechanisms

T cell-driven B cell hyperactivity plays an essential role in driving autoimmune disease development in systemic lupus erythematosus. IL-21 is a member of the type I cytokine family with pleiotropic activities. It regulates B cell differentiation and function, promotes T follicular helper (T(FH)) cell and Th17 cell differentiation, and downregulates the induction of T regulatory cells. Although IL-21 has been implicated in systemic lupus erythematosus, the relative importance of IL-21R signaling in CD4(+) T cells versus B cells is not clear. To address this question, we took advantage of two induced models of lupus-like chronic graft-versus-host disease by using wild-type or IL-21R(-/-) mice as donors in the parent-into-F1 model and as hosts in the Bm12→B6 model. We show that IL-21R expression on donor CD4(+) T cells is essential for sustaining T(FH) cell number and subsequent help for B cells, resulting in autoantibody production and more severe lupus-like renal disease, but it does not alter the balance of Th17 cells and regulatory T cells. In contrast, IL-21R signaling on B cells is critical for the induction and maintenance of germinal centers, plasma cell differentiation, autoantibody production, and the development of renal disease. These results demonstrate that IL-21 promotes autoimmunity in chronic graft-versus-host disease through both CD4(+) T cell- and B cell-intrinsic mechanisms and suggest that IL-21 blockade may attenuate B cell hyperactivity, as well as the aberrant T(FH) cell pathway that contributes to lupus pathogenesis.     

The proinflammatory cytokines IL-2, IL-15 and IL-21 modulate the repertoire of mature human natural killer cell receptors

Natural killer (NK) cells play a crucial role in the immune response to micro-organisms and tumours. Recent evidence suggests that NK cells also regulate the adaptive T-cell response and that it might be possible to exploit this ability to eliminate autoreactive T cells in autoimmune disease and alloreactive T cells in transplantation. Mature NK cells consist of a highly diverse population of cells that expresses different receptors to facilitate recognition of diseased cells and possibly pathogens themselves. Ex vivo culture of NK cells with cytokines such as IL-2 and IL-15 is an approach that permits significant expansion of the NK cell subpopulations, which are likely to have potent antitumour, antiviral, or immunomodulatory effects in autoimmunity. Our data indicate that the addition of IL-21 has a synergistic effect by increasing the numbers of NK cells on a large scale. IL-2 and IL-15 may induce the expression of killer cell immunoglobulin-like receptors (KIRs) in KIR-negative populations, the c-lectin receptor NKG2D and the natural cytotoxic receptor NKp44. The addition of IL-21 to IL-15 or IL-2 can modify the pattern of the KIR receptors and inhibit NKp44 expression by reducing the expression of the adaptor DAP-12. IL-21 also preserved the production of interferon-γ and enhanced the cytotoxic properties of NK cells. Our findings indicate that the proinflammatory cytokines IL-2, IL-15 and IL-21 can modify the peripheral repertoire of NK cells. These properties may be used to endow subpopulations of NK cells with specific phenotypes, which may be used in ex vivo cellular immunotherapy strategies.     

Cytotoxicity of CD56(bright) NK cells towards autologous activated CD4+ T cells is mediated through NKG2D, LFA-1 and TRAIL and dampened via CD94/NKG2A

In mouse models of chronic inflammatory diseases, Natural Killer (NK) cells can play an immunoregulatory role by eliminating chronically activated leukocytes. Indirect evidence suggests that NK cells may also be immunoregulatory in humans. Two subsets of human NK cells can be phenotypically distinguished as CD16(+)CD56(dim) and CD16(dim/-)CD56(bright). An expansion in the CD56(bright) NK cell subset has been associated with clinical responses to therapy in various autoimmune diseases, suggesting an immunoregulatory role for this subset in vivo. Here we compared the regulation of activated human CD4(+) T cells by CD56(dim) and CD56(bright) autologous NK cells in vitro. Both subsets efficiently killed activated, but not resting, CD4(+) T cells. The activating receptor NKG2D, as well as the integrin LFA-1 and the TRAIL pathway, played important roles in this process. Degranulation by NK cells towards activated CD4(+) T cells was enhanced by IL-2, IL-15, IL-12+IL-18 and IFN-α. Interestingly, IL-7 and IL-21 stimulated degranulation by CD56(bright) NK cells but not by CD56(dim) NK cells. NK cell killing of activated CD4(+) T cells was suppressed by HLA-E on CD4(+) T cells, as blocking the interaction between HLA-E and the inhibitory CD94/NKG2A NK cell receptor enhanced NK cell degranulation. This study provides new insight into CD56(dim) and CD56(bright) NK cell-mediated elimination of activated autologous CD4(+) T cells, which potentially may provide an opportunity for therapeutic treatment of chronic inflammation.     

Artificial feeder cells expressing ligands for killer cell immunoglobulin-like receptors and CD94/NKG2A for expansion of functional primary natural killer cells with tolerance to self

Background aimsNatural killer (NK) cells are promising cells for immunotherapy of cancer, and there are ongoing efforts to improve their ex vivo expansion to clinically relevant numbers. This study focused on the development of a C1-, C2-, Bw4 killer cell immunoglobulin-like receptor (KIR) ligand and NKG2A ligand-containing feeder cell line for autonomous expansion of functional NK cells.MethodsPC3^PSCA-derived feeder cells expressing IL-2, 4-1BBL and membrane-bound IL-15-mutDAP12 (mIL-15d) fusion protein in combinations or alone were generated and used for expansion. Expanded NK cells were analyzed with respect to subpopulations, expression of NK cell receptors and immune checkpoint molecules as well as their cytotoxicity against K562 cells, cetuximab-marked tumor cells and autologous B cells.ResultsOnly combinatorial expression of IL-2 plus 4-1BBL or IL-2, 4-1BBL plus mIL-15d in feeder cells efficiently expanded NK cells and supported selective outgrowth of NK cells from peripheral blood mononuclear cell samples. Best expansion of NK cells was achieved using PC3^PSCA-IL-2-4-1BBL-mIL-15d feeder cells. Such expanded NK cells exhibited upregulation of natural cytotoxicity receptors, DNAM-1 and NKG2C and induced expression of high affinity IL-2 receptor, which were paralleled by attenuated KIR and increased expression of NKG2A and ILT2. In addition, elevated TIM-3 levels were noted and PD-1 and T cell immunoreceptor with Ig and ITIM domain (TIGIT) levels remained low. Expanded NK cells were highly cytolytic when encountering K562 cells and cetuximab-marked target cells but remained unresponsive to autologous B cells and target cells with protective levels of human leukocyte antigen.ConclusionsCollectively, the results demonstrate the feasibility of PC3^PSCA-IL-2-4-1BBL-mIL-15d feeder cells for robust expansion of NK cells, which remain tolerant to self and could be used in the future for adoptive cell therapy of cancer.     

IL-12-encoding plasmid has a beneficial effect on spontaneous autoimmune disease in MRL/MP-lpr/lpr mice

Systemic lupus erythematosus (SLE) is characterized by immune abnormalities explained by the overproduction of Th(2)cytokines such as autoantibody production and polyclonal B cell activation. We examined the effect of administering a DNA plasmid encoding IL-12 on the lupus-like disease of MRL/MP-lpr/lpr (MRL/lpr) mice. Treatments were delivered intramuscularly every 4 weeks, starting at 4 weeks of age. This intervention significantly inhibited the accumulation of CD4(-)CD8(-)T cells, and reduced lymphadenopathy and splenomegaly. A significant decrease in serum IgG anti-DNA autoantibody titers was observed, and plasmid IL-12 therapy was also associated with a reduction in the proteinuria and glomerulonephritis characteristic of this disease. Serum IFN-gamma level was increased by inoculating IL-12 encoding plasmid, suggesting that the cytokine balance was skewed towards Th(1). The clinical implications of this suppression of autoimmune disease are also discussed.     

CTL-promoting effects of CD40 stimulation outweigh B cell-stimulatory effects resulting in B cell elimination and disease improvement in a murine model of lupus

CD40/CD40L signaling promotes both B cell and CTL responses in vivo, the latter being beneficial in tumor models. Because CTL may also limit autoreactive B cell expansion in lupus, we asked whether an agonist CD40 mAb would exacerbate lupus due to B cell stimulation or would improve lupus due to CTL promotion. These studies used an induced model of lupus, the parent-into-F1 model in which transfer of DBA/2 splenocytes into B6D2F1 mice induces chronic lupus-like graft-vs-host disease (GVHD). Although agonist CD40 mAb treatment of DBA-->F1 mice initially exacerbated B cell expansion, it also strongly promoted donor CD8 T cell engraftment and cytolytic activity such that by 10 days host B cells were eliminated consistent with an accelerated acute GVHD. CD40 stimulation bypassed the requirement for CD4 T cell help for CD8 CTL possibly by licensing dendritic cells (DC) as shown by the following: 1) greater initial activation of donor CD8 T cells, but not CD4 T cells; 2) earlier activation of host DC; 3) host DC expansion that was CD8 dependent and CD4 independent; and 4) induction of acute GVHD using CD4-depleted purified DBA CD8+ T cells. A single dose of CD40 mAb improved lupus-like renal disease at 12 wk, but may not suffice for longer periods consistent with a need for continuing CD8 CTL surveillance. These results demonstrate that in the setting of lupus-like CD4 T cell-driven B cell hyperactivity, CTL promotion is both feasible and beneficial and the CTL-promoting properties of CD40 stimulation outweigh the B cell-stimulatory properties.     

C-type lectin receptor Dectin3 deficiency balances the accumulation and function of FoxO1-mediated LOX-1+ M-MDSCs in relieving lupus-like symptoms

Recent studies indicate that Toll-like receptors (TLRs) and C-type lectin receptors (CLRs) can function as the signal of pattern recognition receptors, which play a pivotal role in the pathogenesis of the autoimmune disease. Systemic lupus erythematosus (SLE) is a classic autoimmune disease. Previous reports mainly focused on the potential role of TLRs in regulating the development of SLE, but little is known about the role of CLRs in the progression of SLE. Our previous studies showed that the inflammation-mediated accumulation of myeloid-derived suppressor cells (MDSCs) including granulocytic (G-MDSCs) and monocytic (M-MDSCs) participated in the pathogenesis of lupus. Mice deficient in Card9 (the downstream molecule of CLRs) were more susceptible to colitis-associated cancer via promoting the expansion of MDSCs. Whether the abnormal activation of CLRs regulates the expansion of MDSCs to participate in the pathogenesis of lupus remains unknown. In the present study, the expressions of CLRs were examined in both SLE patients and mouse models, revealing the expression of Dectin3 was positively correlated with SLEDAI. Dectin3 deficiency retarded the lupus-like disease by regulating the expansion and function of MDSCs. The mechanistic analysis revealed that Dectin3 deficiency promoted FoxO1-mediated apoptosis of MDSCs. Syk-Akt1-mediated nuclear transfer of FoxO1 increased in Dectin3-deficient MDSCs. Notedly, the accumulation of M-MDSCs mainly decreased in Dectin3^−/− lupus mice, and the nuclear transfer of FoxO1 negatively correlated with the expression of LOX-1 on M-MDSCs. The silencing of FoxO1 expression in Dectin3^−/− mice promoted the expansion of LOX-1⁺ M-MDSCs in vivo, and LOX-1⁺ M-MDSCs increased the differentiation of Th17 cells. Both LOX-1 expression on M-MDSCs and Dectin3 expression on MDSCs increased in patients with SLE. These data indicated that increased LOX-1⁺ M-MDSCs were related to the exacerbation of SLE development and might be potential target cells for the treatment of SLE.Subject terms: Cell signalling, Autoimmunity, Cell death and immune response     

Generating natural killer cells for adoptive transfer: expanding horizons

Natural killer (NK) cells are unique innate lymphoid cells that have therapeutic potential in adoptive cell transfer-based cancer immunotherapy that has been established across a range of early-phase clinical trials. NK cells for use in adoptive transfer therapies are obtained from various sources, including primary NK cells from peripheral blood or apheresis products (autologous or allogeneic) and umbilical cord blood. NK cells have also been generated from CD34+ hematopoietic progenitors, induced pluripotent stem cells, embryonic stem cells and malignant cell lines. Apheresis-derived NK cell products are often administered after brief cytokine-based ex vivo activation, ideally aiming for in vivo expansion and proliferation. NK cells from other sources or from smaller volumes of blood require a longer period of expansion prior to therapeutic use. Although ex vivo NK cell expansion introduces a concern for senescence and exhaustion, there is also an opportunity to achieve higher NK cell doses, modulate NK cell activation characteristics and apply genetic engineering approaches, ultimately generating potent effector cells from small volumes of readily available starting materials. Herein the authors review the field of clinical-grade NK cell expansion, explore the desirable features of an idealized NK cell expansion approach and focus on techniques used in recently published clinical trials.     

Increased interleukin-23 receptor<Superscript>+</Superscript>T cells in peripheral blood mononuclear cells of patients with systemic lupus erythematosus

Introduction  

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by production of autoantibodies and immune complex deposition in various organs. Aberrations in the T lymphocyte compartment and dysregulated cytokine production are key features of SLE pathogenesis and disease progression. Recently, the role of the interleukin (IL)-17/IL-23 axis in the pathogenesis of SLE has been reported. IL-23 and IL-23R are essential for expansion of pathogenic IL-17-producing T lymphocytes and have been shown to be important in the pathogenesis of lupus in animal models.     

Deconvolution of Blood Microarray Data Identifies Cellular Activation Patterns in Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) is a systemic autoimmune disease with a complex spectrum of cellular and molecular characteristics including several dramatic changes in the populations of peripheral leukocytes. These changes include general leukopenia, activation of B and T cells, and maturation of granulocytes. The manifestation of SLE in peripheral blood is central to the disease but is incompletely understood. A technique for rigorously characterizing changes in mixed populations of cells, microarray expression deconvolution, has been applied to several areas of biology but not to SLE or to blood. Here we demonstrate that microarray expression deconvolution accurately quantifies the constituents of real blood samples and mixtures of immune-derived cell lines. We characterize a broad spectrum of peripheral leukocyte cell types and states in SLE to uncover novel patterns including: specific activation of NK and T helper lymphocytes, relationships of these patterns to each other, and correlations to clinical variables and measures. The expansion and activation of monocytes, NK cells, and T helper cells in SLE at least partly underlie this disease''s prominent interferon signature. These and other patterns of leukocyte dynamics uncovered here correlate with disease severity and treatment, suggest potential new treatments, and extend our understanding of lupus pathology as a complex autoimmune disease involving many arms of the immune system.     

Analysis of ex vivo expanded and activated clinical-grade human NK cells after cryopreservation

Background aimsSeveral methods to expand and activate (EA) NK cells ex vivo have been developed for the treatment of relapsed or refractory cancers. Infusion of fresh NK cells is generally preferred to the infusion of cryopreserved/thawed (C/T) NK cells because of concern that cryopreservation diminishes NK cell activity. However, there has been little head-to-head comparison of the functionality of fresh versus C/T NK cell products.MethodsWe evaluated activity of fresh and C/T EA NK cells generated by interleukin (IL)-15, IL-2 and CD137L expansion.ResultsAnalysis of C/T NK cell products demonstrated decreased recovery of viable CD56⁺ cells, but the proportion of NK cells in the C/T EA NK cell product did not decrease compared with the fresh EA NK cell product. Fresh and C/T EA NK cells demonstrated increased granzyme B compared with NK cells pre-expansion, but only fresh EA NK cells showed increased NKG2D. Compared with fresh EA NK cells, cytotoxic ability of C/T EA NK cells was reduced, but C/T EA NK cells remained potently cytotoxic against tumor cells via both antibody-independent and antibody-dependent mechanisms within 4 h post-thaw. Fresh EA NK cells generated high levels of gamma interferon (IFN-γ), which was abrogated by JAK1/JAK2 inhibition with ruxolitinib, but C/T EA NK cells showed lower IFN-γ unaffected by JAK1/JAK2 inhibition.DiscussionUsage of C/T EA NK cells may be an option to provide serial “boost” NK cell infusions from a single apheresis to maximize NK cell persistence and potentially improve NK-induced responses to refractory cancer.     

A proinflammatory role of IL-18 in the development of spontaneous autoimmune disease.

Serum from patients with systemic lupus erythematosus (SLE) contained significantly higher concentrations of IL-18 than normal individuals. MRL/lpr mice, which develop spontaneous lupus-like autoimmune disease, also had higher serum levels of IL-18 than wild-type MRL/++ mice. Daily injections of IL-18 or IL-18 plus IL-12 resulted in accelerated proteinuria, glomerulonephritis, vasculitis, and raised levels of proinflammatory cytokines in MRL/lpr mice. IL-18-treated MRL/lpr mice also developed a "butterfly" facial rash resembling clinical SLE. In contrast, MRL/lpr mice treated with IL-18 plus IL-12 did not develop a facial rash. The facial lesion in the IL-18-treated mice showed epidermal thickening with intense chronic inflammation accompanied by increased apoptosis, Ig deposition, and early systemic Th2 response compared with control or IL-12 plus IL-18-treated mice. These data therefore show that IL-18 is an important mediator of lupus-like disease and may thus be a novel target for therapeutic intervention of spontaneous autoimmune diseases.     

Reduced proportions of natural killer T cells are present in the relatives of lupus patients and are associated with autoimmunity

Introduction

Systemic lupus erythematosus is a genetically complex disease. Currently, the precise allelic polymorphisms associated with this condition remain largely unidentified. In part this reflects the fact that multiple genes, each having a relatively minor effect, act in concert to produce disease. Given this complexity, analysis of subclinical phenotypes may aid in the identification of susceptibility alleles. Here, we used flow cytometry to investigate whether some of the immune abnormalities that are seen in the peripheral blood lymphocyte population of lupus patients are seen in their first-degree relatives.

Methods

Peripheral blood mononuclear cells were isolated from the subjects, stained with fluorochrome-conjugated monoclonal antibodies to identify various cellular subsets, and analyzed by flow cytometry.

Results

We found reduced proportions of natural killer (NK)T cells among 367 first-degree relatives of lupus patients as compared with 102 control individuals. There were also slightly increased proportions of memory B and T cells, suggesting increased chronic low-grade activation of the immune system in first-degree relatives. However, only the deficiency of NKT cells was associated with a positive anti-nuclear antibody test and clinical autoimmune disease in family members. There was a significant association between mean parental, sibling, and proband values for the proportion of NKT cells, suggesting that this is a heritable trait.

Conclusions

The findings suggest that analysis of cellular phenotypes may enhance the ability to detect subclinical lupus and that genetically determined altered immunoregulation by NKT cells predisposes first-degree relatives of lupus patients to the development of autoimmunity.     

Intraperitoneal delivery of human natural killer cells for treatment of ovarian cancer in a mouse xenograft model

Background aimsThere is an urgent need for novel therapeutic strategies for relapsed ovarian cancer. Dramatic clinical anti-tumor effects have been observed with interleukin (IL)-2 activated natural killer (NK) cells; however, intravenous delivery of NK cells in patients with ovarian cancer has not been successful in ameliorating disease. We investigated in vivo engraftment of intraperitoneally (IP) delivered NK cells in an ovarian cancer xenograft model to determine if delivery mode can affect tumor cell killing and circumvent lack of NK cell expansion.MethodsAn ovarian cancer xenograft mouse model was established to evaluate efficacy of IP-delivered NK cells. Tumor burden was monitored by bioluminescent imaging of luciferase-expressing ovarian cancer cells. NK cell persistence, tumor burden and NK cell trafficking were evaluated. Transplanted NK cells were evaluated by flow cytometry and cytotoxicity assays.ResultsIP delivery of human NK cells plus cytokines led to high levels of circulating NK and was effective in clearing intraperitoneal ovarian cancer burden in xenografted mice. NK cells remained within the peritoneal cavity 54 days after injection and had markers of maturation. Additionally, surviving NK cells were able to kill ovarian cancer cells at a rate similar to pre-infusion levels, supporting that in vivo functionality of human NK cells can be maintained after IP infusion.ConclusionsIP delivery of NK cells leads to stable engraftment and antitumor response in an ovarian cancer xenograft model. These data support further pre-clinical and clinical evaluation of IP delivery of allogeneic NK cells in ovarian cancer.     

Cutting edge: protein phosphatase 2A confers susceptibility to autoimmune disease through an IL-17-dependent mechanism

The contribution of individual molecular aberrations to the pathogenesis of systemic lupus erythematosus (SLE), an autoimmune disease that affects multiple organs, is often difficult to evaluate because of the presence of abundant confounding factors. To assess the effect of increased expression of the phosphatase protein phosphatase 2A (PP2A) in T cells, as recorded in SLE patients, we generated a transgenic mouse that overexpresses the PP2Ac subunit in T cells. The transgenic mouse displays a heightened susceptibility to immune-mediated glomerulonephritis in the absence of other immune defects. CD4(+) T cells produce increased amounts of IL-17 while the number of neutrophils in the peripheral blood is increased. IL-17 neutralization abrogated the development of glomerulonephritis. We conclude that increased PP2Ac expression participates in SLE pathogenesis by promoting inflammation through unchecked IL-17 production and facilitating the development of end-organ damage.     

Lack of the long pentraxin PTX3 promotes autoimmune lung disease but not glomerulonephritis in murine systemic lupus erythematosus

The long pentraxin PTX3 has multiple roles in innate immunity. For example, PTX3 regulates C1q binding to pathogens and dead cells and regulates their uptake by phagocytes. It also inhibits P-selectin-mediated recruitment of leukocytes. Both of these mechanisms are known to be involved in autoimmunity and autoimmune tissue injury, e.g. in systemic lupus erythematosus, but a contribution of PTX3 is hypothetical. To evaluate a potential immunoregulatory role of PTX3 in autoimmunity we crossed Ptx3-deficient mice with Fas-deficient (lpr) C57BL/6 (B6) mice with mild lupus-like autoimmunity. PTX3 was found to be increasingly expressed in kidneys and lungs of B6lpr along disease progression. Lack of PTX3 impaired the phagocytic uptake of apoptotic T cells into peritoneal macrophages and selectively expanded CD4/CD8 double negative T cells while other immune cell subsets and lupus autoantibody production remained unaffected. Lack of PTX3 also aggravated autoimmune lung disease, i.e. peribronchial and perivascular CD3+ T cell and macrophage infiltrates of B6lpr mice. In contrast, histomorphological and functional parameters of lupus nephritis remained unaffected by the Ptx3 genotype. Together, PTX3 specifically suppresses autoimmune lung disease that is associated with systemic lupus erythematosus. Vice versa, loss-of-function mutations in the Ptx3 gene might represent a genetic risk factor for pulmonary (but not renal) manifestations of systemic lupus or other autoimmune diseases.     

Natural killer cells have a synergistic anti-tumor effect in combination with chemoradiotherapy against head and neck cancer

BackgroundThe use of natural killer (NK) cells is a promising approach in the field of cancer immunotherapy; however, combination treatments are required to enhance the effects of NK cell immunotherapy. In this study, we assessed the potential of irradiation and cisplatin as a chemoradiotherapy (CRT) regimen to augment the effects of NK cell immunotherapy in head and neck squamous cell carcinoma (HNSCC).MethodsNK cells were expanded using our recently established K562-OX40 ligand and membrane-bound interleukin (IL)-18 and IL-21 feeder cells in the presence of IL-2/IL-15 from peripheral blood of healthy donors.ResultsThe results showed an increase in the purity of NK cells and expression of activation markers such as NKG2D and lymphocyte function–associated antigen 1 during the expansion process, which is positively correlated to the NK cell infiltration and overall survival in patients with HNSCC. CRT induced NK cell activation ligand (ULBP2) and adhesion molecules (ICAM-1, -2 and -3) on HNSCC, leading to enhanced cytotoxicity of NK cells against HNSCC.ConclusionsOur findings suggest that the NK cells have a potent anti-tumor effect in combination with CRT against HNSCC.