Dormancy and NKG2D system in brain metastases: Analysis of immunogenicity.

Patients with breast cancer (BC) and lung cancer (LC) are prone to developing brain metastases, which are associated with devastating prognoses. Dormant tumor cells, a population of non­apoptotic quiescent cells and immunological escape mechanisms, including the Natural Killer Group 2 member D (NKG2D) receptor­ligand system, represent potential mechanisms of tumor recurrence. To date, the immunological characteristics of dormant tumor cells concerning the NKG2D system in cerebral malignancies are mostly unknown. In the present study, an extensive characterization of dormant and NKG2D ligand (NKG2DL)+ cells in cerebral metastases was performed. The expression profiles and localization patterns of various NKG2DL and several dormancy markers were analyzed in solid human brain metastases from patients with BC and LC using immunostaining and reverse transcription­quantitative polymerase chain reaction analyses. Statistical analysis was performed using Student's t­test and Bravais­Pearson correlation analysis. Not only 'peripheral', but also 'central' dormancy markers, which had been previously described in primary brain tumors, were identified in all cerebral metastases at detectable levels at protein and mRNA levels. Notably, the majority of NKG2DL+ cells were also positive for 'central' dormancy markers, but not 'peripheral' dormancy markers in both patient groups. This cell population may represent a promising future therapeutic target.

Sesamolin affects both natural killer cells and cancer cells in order to create an optimal environment for cancer cell sensitization.

In our previous study, we demonstrated that sesamolin can increase the level of cancer cell susceptibility to natural killer (NK) cell mediated cytolysis when it treats cancer cells. The present study attempted to demonstrate the direct influence of sesamolin on NK cells. To achieve the study goal, an NK cell (NK-92MI) or Raji cell was treated with sesamolin for use in the analysis of the cytolytic activity of NK cells. When NK-92MI cells were treated with sesamolin, the cytolysis activities of NK cells increased depending on the concentration of sesamolin. However, the highest cytolytic activity of NK cells was observed when Raji and NK-92MI cells were treated with sesamolin at 20 µg/mL and 40 µg/mL, respectively. Sesamolin also increased the expression of the degranulation marker, CD107a, on the surface of NK cells and the production of immune-activation cytokine, IFN-γ, from NK cells. The effects of sesamolin on NK cells were reproduced in the naïve NK cells. We found that sesamolin effects are triggered by the result of phosphorylation of the p38, ERK1/2 and JNK pathways in NK cells. Taken together, this study proved that NK cell activity can be increased by the stimulation of sesamolin on NK cells as well as cancer cells.

The early expansion of anergic NKG2Apos/CD56dim/CD16neg natural killer represents a therapeutic target in haploidentical hematopoietic stem cell transplantation.

Natural killer cells are the first lymphocyte population to reconstitute early after non-myeloablative and T cell-replete haploidentical hematopoietic stem cell transplantation with post-transplant infusion of cyclophosphamide. The study herein characterizes the transient and predominant expansion starting from the second week following haploidentical hematopoietic stem cell transplantation of a donor-derived unconventional subset of NKp46neg-low/CD56dim/CD16neg natural killer cells expressing remarkably high levels of CD94/NKG2A. Both transcription and phenotypic profiles indicated that unconventional NKp46neg-low/CD56dim/CD16neg cells are a distinct natural killer cell subpopulation with features of late stage differentiation, yet retaining proliferative capability and functional plasticity to generate conventional NKp46pos/CD56bright/CD16neg-low cells in response to interleukin-15 plus interleukin-18. While present at low frequency in healthy donors, unconventional NKp46neg-low/CD56dim/CD16neg cells are greatly expanded in the seven weeks following haploidentical hematopoietic stem cell transplantation, and express high levels of the activating receptors NKG2D and NKp30 as well as of the lytic granules Granzyme-B and Perforin. Nonetheless, NKp46neg-low/CD56dim/CD16neg cells displayed a markedly defective cytotoxicity that could be reversed by blocking the inhibitory receptor CD94/NKG2A. These data open new and important perspectives to better understand the ontogenesis/homeostasis of human natural killer cells and to develop a novel immune-therapeutic approach that targets the inhibitory NKG2A check-point, thus unleashing natural killer cell alloreactivity early after haploidentical hematopoietic stem cell transplantation.

Regulatory effects of dexamethasone on NK and T cell immunity.

Glucocorticoids (GCs) act via the intracellular glucocorticoid receptor (GR), which can regulate the expression of target genes. With regard to the immune system, GCs may affect both innate and adaptive immunity. Our study analyzed the immunoregulatory effects of dexamethasone (Dex) treatment on splenic T, Treg, NK and NKT cells by treating C57Bl6 mice with various doses of Dex. We observed that treatment with Dex decreased the number of NK cells in the spleen and suppressed their activity. In particular, the expression of both Ly49G and NKG2D receptors was decreased by Dex. However, Dex did not affect the population of NKT cells. With regard to splenic T cells, our results show a dose-dependent reduction in CD3+, CD4+, CD8+, CD44+ and CD8+CD122+ T cells, but a stimulatory effect on CD4+CD25+ regulatory T cells by Dex treatment. In addition, treatment with Dex suppressed anti-tumor immune response in a mouse EG7 tumor model. We conclude that Dex may suppress both T- and NK-mediated immunity.

Endogenous TWEAK is critical for regulating the function of mouse uterine natural killer cells in an immunological model of pregnancy loss.

Uterine natural killer (uNK) cells are the most abundant lymphocyte population in the feto-maternal interface during early gestation, and uNK cells play a significant role in the establishment and maintenance of pregnancy-related vascularization, as well as in tolerance to the fetus. Tumour necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor-inducible molecule (Fn14), are involved in preventing local cytotoxicity and counterbalancing the cytotoxic function of uNK cells. Here, we studied the regulation of TWEAK/Fn14-mediated innate immunity in the uterus using a lipopolysaccharide (LPS)-induced model of abortion in pregnant mice. Specifically, we detected the expression of TWEAK and Fn14 in the uterus and in uNK cells following LPS treatment. Our results revealed that TWEAK and Fn14 are expressed by uNK cells in pregnant mice; in particular, it appears that the cytokine TWEAK is primarily derived from uNK cells. Interestingly, the down-regulation of TWEAK in uNK cells and the up-regulation of the Fn14 receptor in the uterus in LPS-treated mice may contribute to the disruption of decidual homeostasis by altering uNK cell cytotoxicity - ultimately leading to fetal rejection. In conclusion, the present study strongly suggests that the TWEAK-Fn14 axis in uNK cells is involved in maintaining the tolerance necessary for successful pregnancy.

MICA/B and ULBP1 NKG2D ligands are independent predictors of good prognosis in cervical cancer.

BACKGROUND: NKG2D (natural killer group 2, member D) is thought to play an important role in mediating the activation of anticancer immune response. Expression of NKG2D ligands (NKG2DLs) is pronounced in malignancies and the heterogeneity of NKG2DL expression remains unclear. Here, we investigate the expression and clinical significance of NKG2DLs in cervical cancer. METHODS: Immunohistochemical analyses of MICA/B, ULBP1, ULBP2, ULBP3, RAET1E, and RAET1G were performed using tissue microarray analysis of 200 cervical cancers, 327 high-grade cervical intraepithelial neoplasias (CINs), 99 low-grade CINs, and 541 matched nonadjacent normal cervical epithelial tissues and compared the data with clinicopathologic variables, including the survival of cervical cancer patients. RESULTS: MICA/B, ULBP1, and RAET1E expression was higher in cervical cancer than in low-grade CIN (p<0.001, p=0.012, p=0.013, respectively) and normal cervix (all p<0.001). Among these markers, expression of ULBP1 was significantly different depending on patient tumor stage (p=0.010) and tumor size (p=0.045). ULBP1 expression was correlated with MICA/B (p<0.001) and ULBP2 (p=0.002) expression in cervical cancer. While MICA/B+ or ULBP1+ patients had improved disease-free survival time (p=0.027 and p=0.009, respectively) relative to that of the low expression group, RAET1E+ or RAET1G+ was correlated with shorter survival time (p=0.018 and p=0.029, respectively). However, in terms of overall survival, the ULBP1+ group had significantly longer survival time than the low expression group (p=0.009). Multivariate analysis indicated that MICA/B+/ULBP1+ (HR=0.16, p=0.015) and ULBP1+ (HR=0.31, p=0.024) are independent prognostic factors of disease-free survival in cervical cancer. CONCLUSIONS: High expression of either ULBP1 or MICA/B and ULBP1 combined is an indicator of good prognosis in cervical cancer, suggesting their potential utility as prognostic tests in clinical assessment.

Augmenting the expression of NKp44 molecule and the natural killer activity in peripheral blood mononuclear cells from patients with malignant colorectal carcinoma.

OBJECTIVE: NKp44 and NKG2D are of the main NK activating receptors involved in recognition and killing of tumors. Here we studied the stimulatory effects of PHA and/or K562 cell line on induction of NKp44 and NKG2D expression and the NK activity of PBMCs from patients with colorectal carcinoma (CRC). MATERIALS AND METHODS: Peripheral blood samples were collected from 10 patients with CRC. The peripheral blood mononuclear cells (PBMCs) from each patient received a single stimulation with PHA or double stimulation with PHA and irradiated K562 cell line (iK562). The expression of CD56, NKG2D and NKp44 were detected by flowcytometry. The NK activity of PBMCs against a colorectal carcinoma cell line named as SW742 was determined with 51Cr-release assay. RESULTS: Double stimulation of PBMCs with PHA+iK562 significantly augmented the number CD56(+) cells compared to PHA alone and non-stimulated PBMCs (P<0.000, P<0.0000; respectively). A single stimulation of PBMCs with PHA resulted in an enhancement in NKG2D and NKp44 expression from 16.6±3.3% (for non-stimulated PBMCs) to 42±5.6% and 48.1±3.8% respectively (p<0.05). Double stimulation of PBMCs augmented the NKp44 expression significantly in comparison with single stimulation with PHA (73.6±12%, p<0.05). Double stimulation of PBMCs significantly enhanced the NK activity against SW742 target cells compared to single stimulation with PHA (p<0.05). DISCUSSION AND CONCLUSION: Our results demonstrated that the mitogen and iK562 exposure to PBMCs can significantly improve NK activity which is co-related to the higher expression of NKp44 and NKG2D. These data may help to improve cancer immunotherapy protocols.

[Expression and significance of the NK cell receptors in primary hepatocellular carcinoma and paracancerous tissues].

AIM: To investigate the expression of the activating and inhibitory receptors on the surface of NK cells of primary hepatocellular carcinoma and its adjacent tissues, and the relationship between these two receptors and occurrence and development of primary liver cancer was analyzed. METHODS: The number and activity of the NK cells, the expression of the activating and the inhibitory receptors on the surface of those cells were detected flow cytometry and immunohistochemistry, which were obtained from 52 cases of primary hepatocellular carcinoma and its adjacent tissues. The relative analysis was done between those results and clinical relative factors. RESULTS: In the tissues of primary hepacellular carcinoma, the number of NK cells is lower than that in the adjacent tissues obviously (P<0.01); the expression of activating receptors, NKG2D and NKP44, is also lower than that in the adjacent tissues obviously (P<0.05); the expression of inhibitory receptors, CD158b and CD159a, is significantly higher than that in the adjacent tissues (P<0.05). A negative correlation was found between the expression of NKG2D, NKP30 and NKP44 and the clinical stage of the liver cancer. The expression of NKG2D, NKP30 and NKP44 was higher in patients with early and middle stages (P<0.05). The content of the inhibitory receptors of NK cells, CD158b and CD159a, is higher in tissues from patients with advanced cancer stage (P<0.05). That's also correlated with the level of AFP and the HBsAg. There is no significant statistical difference between the expression of NK receptors and the distant metastasis, tumor differentiation as well as the tumor size (P>0.05). CONCLUSION: The decrease of NK cell numbers and the activating NK cell receptors and the increase of the inhibitory receptors would be relevant to the incidence of primary hepacellular carcinoma.

Expression of NKG2D and CD107 in CD8(+) effector memory lymphocytes in Churg-Strauss syndrome.

OBJECTIVES: Churg-Strauss syndrome (CSS) is a necrotising vasculitis of small vessels in which oligoclonally expanded TCR Vß CD8+ effector memory T cells populations (TEM) may be involved in vasculitic damage. The aim of this study was to assess the functional role of CD8+ T cells in CSS patients by flow cytometry analysis of membrane expression of cytotoxic markers NKG2D and CD107a. METHODS: Immunostaining of peripheral T cells and effector memory lymphocytes (TEM) from CSS patients and controls was performed by gating CD28 and CD45RA in the CD8+NKG2D+ and CD4+NKG2D+ populations. CD107a expression was evaluated in both whole CD8+ and CD4+ and the TEM cells by gating CD62 and CD45RA following polyclonal stimulation. RESULTS: NKG2D expression was shifted toward the CD8+CD28- fraction of T cells in CSS patients compared to healthy controls (56.1±25.8% versus 17.2±7.3%, respectively, p=0.002). CD8+Vß+ expanded T cells showed a significantly increased expression of NKG2D compared to the whole CD8+ T cell population (91.4±1.9% versus 79.7±3.8%, respectively, p=0.015). Moreover the CD8+ population from CSS upregulates CD107a on its surface upon polyclonal stimulation in a significantly higher proportion than healthy subjects (26.2±10.8% versus 8.2±2.9%, p=0.0031) and the majority CD8+ CD107+ cells from CSS patients showed a TEM phenotype compared to controls (64.8±4.9% vs. 19.8±2.9, respectively, p<0.001). CONCLUSIONS: In CSS, CD8+ TEM lymphocytes show markers of cytotoxic activity, which suggests a role for these cells in vasculitic damage.

Control of Mycobacterium tuberculosis growth by activated natural killer cells.

We characterized the underlying mechanisms by which glutathione (GSH)-enhanced natural killer (NK) cells inhibit the growth of Mycobacterium tuberculosis (M. tb) inside human monocytes. We observed that in healthy individuals, treatment of NK cells with N-acetyl cysteine (NAC), a GSH prodrug in conjunction with cytokines such as interleukin (IL)-2 + IL-12, resulted in enhanced expression of NK cytotoxic ligands (FasL and CD40L) with concomitant stasis in the intracellular growth of M. tb. Neutralization of FasL and CD40L in IL-2 + IL-12 + NAC-treated NK cells resulted in abrogation in the growth inhibition of M. tb inside monocytes. Importantly, we observed that the levels of GSH are decreased significantly in NK cells derived from individuals with HIV infection compared to healthy subjects, and this decrease correlated with a several-fold increase in the growth of M. tb inside monocytes. This study describes a novel innate defence mechanism adopted by NK cells to control M. tb infection.

Enhancement of natural killer cell effector functions against selected lymphoma and leukemia cell lines by dasatinib.

As NK cell immunotherapy is still poorly successful, combinations with drugs enhancing NK cell activity are of major interest. NK large granular lymphocyte expansions associated with improved survival have been described under monotherapy with the Bcr-Abl/Src inhibitor dasatinib, which inhibits NK cell functions in vitro. As Src kinases play a major role in inhibitory and activating signaling pathways of NK cells, both outcomes appear plausible. To clarify these contradictory observations and potentially enable the use of dasatinib as adjuvant, we analyzed how clinically relevant doses promote NK cell effector functions. Polyclonal human NK cells were studied ex vivo. Functional outcomes assessed included conjugate formation, calcium flux, receptor regulation, cytokine production, degranulation, cytotoxicity, apoptosis induction and signal transduction. While dasatinib inhibits NK cell effector functions during functional assays, 24 hr pretreatment of NK cells followed by washout of dasatinib, led to dose-dependent enhancement of cytokine production, degranulation marker expression and cytotoxicity against selected lymphoma and leukemia cell lines. Mechanistically, this was neither due to an altered viability of NK cells nor increased NKG2D, LFA-1 or conjugate formation with target cells. Receptor proximal signaling events were inhibited. However, a slight time dependent enhancement of Vav phosphorylation was observed under certain circumstances. The shift in Vav phosphorylation level may be one major mechanism for NK cell activity enhancement induced by dasatinib. Our findings argue for a careful timing and dosing of dasatinib application during leukemia/lymphoma treatment to enhance NK cell immunotherapeutic efforts.

In vitro increased natural killer cell activity of metastatic melanoma patients with interferon-α alone as opposed to its combination with 13-cis retinoic acid is associated with modulation of NKG2D and CD161 activating receptor expression.

PURPOSE: Considering tumor-induced suppression of natural killer (NK) cell activity the aim of this study was to investigate the in vitro effect of a standard immunotherapeutic cytokine, interferon (IFN)α, and a less investigated agent, 13-cis retinoic acid (RA) on the functional and receptor characteristics of CD16-defined NK cells and their functionally diverse dim and bright subsets in patients with metastatic melanoma (MM). METHODS: Peripheral blood lymphocytes (PBL) of patients with clinical stage IV MM were stimulated in vitro for 18 h in RPMI 1640 culture medium (CM) alone, CM supplemented with IFN-α (250 U7sol;ml), RA (10-6M) and their combination. NK cell activity was determined using standard 4 h radioactive cytotoxicity assay, while the expression of activating (NKG2D, CD1617rpar; and inhibitory (CD158a, CD158b) NK cell receptors on CD3-CD16+ NK cells and their functional bright and dim subsets were analyzed by flow cytometry. RESULTS: NK cell cytotoxic activity was increased after in vitro treatment with IFN-α alone and in combination with RA, while only IFN-α induced increase in NKG2D and CD161 activating NK cell receptor expression. Contrary to this, RA treatment increased the expression of inhibitory KIR CD158b. IFN-α-obtained increase in CD161 expression was due to its induction on both NK cell subsets, while for NKG2D only on CD16bright subset. CONCLUSION: The favorable enhancement of NK cell activity of MM patients obtained with IFN-α is associated with upregulation of activating NKG2D and CD161 receptors, while the lack of RA-associated upregulation is probably due to the shown increased expression of inhibitory KIR receptor CD158b after in vitro treatment with this agent.

The soluble major histocompatibility complex class I-related chain A protein reduced NKG2D expression on natural killer and T cells from patients with prolactinoma and non-secreting pituitary adenoma.

This study analyses aspects of the immune system in prolactinoma and non-secreting pituitary adenoma. Serum soluble major histocompatibility complex class I-related chain A protein (sMICA) concentrations were measured by enzyme-linked immunosorbent assay. NKG2D-expressing natural killer and T cells were analyzed by flow cytometry. A correlation analysis was also performed to associate sMICA levels with NKG2D expression. The expression of MICA was examined in specific tissues by use of the reverse transcription-polymerase chain reaction. A significant amount of sMICA was detected in the serum of nearly all patients. We found decreased percentage and mean fluorescence intensity of NKG2D-expressing natural killer and T cells from patients with prolactinoma and non-secreting pituitary adenoma compared to those from healthy donors. Pearson analysis showed a negative correlation between sMICA and NKG2D-expressing cells. The immune-escape of pituitary adenoma is related to the down-regulation of NKG2D and the up-regulation of its ligand MICA.

Activation of natural killer cells during acute infection with hepatitis C virus.

BACKGROUND & AIMS: Natural killer (NK) cells are essential early after infection, not only for viral containment but also for timely and efficient induction of adaptive responses. An inhibitory effect of hepatitis C virus (HCV)-E2 proteins on NK cells has been reported, but the features of NK cell responses in the acute phase of hepatitis C are still largely undefined. Therefore, the aim of this study was to characterize the function and phenotype of NK cells in the acute phase of infection and compare individuals with chronic and self-limited outcomes. METHODS: Twenty-two individuals with acute HCV infection, 14 with chronic evolution, and 8 with self-limited infection, were studied using NK phenotypic and functional assays. RESULTS: An increased expression of NKG2D on both CD56(bright) and CD56(dim) NK cells was detected in patients with acute HCV, irrespective of the outcome, as compared with healthy controls. Also, interferon gamma production and cytotoxicity by NK cells were higher in individuals with acute HCV infection than in healthy controls. Subset analysis showed increased interferon gamma production in both NK cell subsets carrying group 1 and group 2 HLA-C-specific killer cell immunoglobulin-like receptors. However, increased CD107a was noted only on NK cells expressing the group 1 HLA-C-specific killer cell immunoglobulin-like receptor and was maximal in self-limited infection. CONCLUSIONS: Our data show that in the acute phase of HCV infection, NK cells are activated regardless of outcome, with no evidence of a suppressive effect of HCV on NK cell function.

Radiotherapy-induced changes of peripheral blood lymphocyte subpopulations in cervical cancer patients: relationship to clinical response.

PURPOSE: To determine the absolute number and percentage of peripheral blood lymphocyte subpopulations positive (+) cells CD8(+), CD8(+)NKG2D(+), CD8(+), Granzyme B(+) (GrB), CD16(+), CD16(+)NKG2D(+), CD56(+) and CD56(+)NKG2D(+) in cervical cancer patients before and after radiotherapy (RT), and to analyze whether their changes are related to the clinical response. MATERIALS AND METHODS: Stage IIB - IVA cervical cancer patients received external irradiation and concomitant intracavitary brachytherapy. Blood samples for immunophenotypic analysis by flow cytometry were collected from each patient one day before starting RT and one day after completing RT. Fifteen healthy volunteers served as controls. Surface marker expression and granzyme B positivity were quantified on FACSCalibur flow cytometer. RESULTS: Unlike their absolute numbers, the percentages of all analyzed lymphocyte subsets of all patients, including those with complete response (CR), were significantly increased (p <0.05) after RT. Only in patients with progressive disease (PD), CD8(+), CD8(+)NKG2D(+), CD16(+) and CD56(+)NKG2D(+) lymphocytes were not significantly increased. In healthy volunteers, the percentage of CD8(+)GrB(+) lymphocytes was lower than in patients after RT, while the percentages of CD56(+) and CD56(+)NKG2D(+) cells were higher than in patients before RT (p <0.05). CONCLUSION: Our data indicate that RT, besides its direct cytoreductive effect on tumor cells, may contribute to better immunological control of cervical cancer.

Prospective study of natural killer cell phenotype in recurrent hepatitis C virus infection following liver transplantation.

BACKGROUND/AIMS: Graft re-infection invariably occurs after liver transplantation (OLT) for chronic hepatitis C and disease progression is unpredictable. We prospectively examined peripheral blood mononuclear cells (PBMC) subsets and natural killer (NK) cell receptors (NKRs) in patients with recurrent hepatitis C post-OLT. METHODS: PBMC were obtained at baseline and at different time points after OLT. NKRs were identified using monoclonal antibodies by flow cytometry. RESULTS: The proportions of NK, natural T (NT), total and gammadelta T cells were significantly reduced (p<0.01) 7 days post-transplant, probably as a result of graft repopulation. NKG2D+ NK cells were significantly higher compared with healthy controls (p<0.01), declined post-OLT and subsequently returned to baseline values. This, together with a progressive increase in the proportion of CD94/NKG2C+ NK cells over time (p< or = 0.01), appeared to be related to hepatitis C recurrence. There was a statistically significant correlation between expression of the natural cytotoxicity receptors (NCRs) and ALT (p<0.05), supporting the hypothesis that NK cells participate in the necroinflammatory process. CONCLUSIONS: The data are compatible with homing of immune cells to the liver allograft after surgery, most of which return to pre-OLT levels. HCV recurrence may cause variations in selected NKRs expression akin to other viral infections.

TNK cells (NKG2D+ CD8+ or CD4+ T lymphocytes) in the control of human tumors.

Innate and adaptive immune responses have many interactions that are regulated by the balance of signals initiated by a variety of activatory and inhibitory receptors. Among these, the NKG2D molecule was identified as expressed by T lymphocytes, including most CD8+ cells and a minority of CD4+ cells, designated TNK cells in this paper. Tumor cells may overexpress the stress-inducible NKG2D ligands (NKG2DLs: MICA/B, ULBPs) and the NKG2D signaling has been shown to be involved in lymphocyte-mediated anti-tumor activity. Aberrant expression of NKG2DLs by cancer cells, such as the release of soluble form of NKG2DLs, can lead to the impairment of these immune responses. Here, we discuss the significance of NKG2D in TNK-mediated anti-tumor activity. Our studies demonstrate that NKG2D+ T cells (TNK) are commonly recruited at the tumor site in melanoma patients where they may exert anti-tumor activity by engaging both TCR and NKG2D. Moreover, NKG2D and TCR triggering was also observed by peripheral blood derived T lymphocyte- or T cell clone-mediated tumor recognition, both in melanoma and colorectal cancer (CRC) patients. Notably, heterogeneous expression of NKG2DLs was found in melanoma and CRC cells, with a decrease of these molecules along with tumor progression. Therefore, through the mechanisms that govern NKG2D engagement in anti-tumor activity and the expression of NKG2DLs by tumor cells that still need to be dissected, we showed that NKG2D expressing TNK cells are a relevant T cell subtype for immunosurveillance of tumors and we propose that new immunotherapeutic interventions for cancer patients should be aimed also at enhancing NKG2DLs expression by tumor cells.