TCR-independent CD137 (4-1BB) signaling promotes CD8+-exhausted T cell proliferation and terminal differentiation.

CD137 (4-1BB)-activating receptor represents a promising cancer immunotherapeutic target. Yet, the cellular program driven by CD137 and its role in cancer immune surveillance remain unresolved. Using T cell-specific deletion and agonist antibodies, we found that CD137 modulates tumor infiltration of CD8+-exhausted T (Tex) cells expressing PD1, Lag-3, and Tim-3 inhibitory receptors. T cell-intrinsic, TCR-independent CD137 signaling stimulated the proliferation and the terminal differentiation of Tex precursor cells through a mechanism involving the RelA and cRel canonical NF-κB subunits and Tox-dependent chromatin remodeling. While Tex cell accumulation induced by prophylactic CD137 agonists favored tumor growth, anti-PD1 efficacy was improved with subsequent CD137 stimulation in pre-clinical mouse models. Better understanding of T cell exhaustion has crucial implications for the treatment of cancer and infectious diseases. Our results identify CD137 as a critical regulator of Tex cell expansion and differentiation that holds potential for broad therapeutic applications.

Eomes-Dependent Loss of the Co-activating Receptor CD226 Restrains CD8+ T Cell Anti-tumor Functions and Limits the Efficacy of Cancer Immunotherapy.

CD8+ T cells within the tumor microenvironment (TME) are exposed to various signals that ultimately determine functional outcomes. Here, we examined the role of the co-activating receptor CD226 (DNAM-1) in CD8+ T cell function. The absence of CD226 expression identified a subset of dysfunctional CD8+ T cells present in peripheral blood of healthy individuals. These cells exhibited reduced LFA-1 activation, altered TCR signaling, and a distinct transcriptomic program upon stimulation. CD226neg CD8+ T cells accumulated in human and mouse tumors of diverse origin through an antigen-specific mechanism involving the transcriptional regulator Eomesodermin (Eomes). Despite similar expression of co-inhibitory receptors, CD8+ tumor-infiltrating lymphocyte failed to respond to anti-PD-1 in the absence of CD226. Immune checkpoint blockade efficacy was hampered in Cd226-/- mice. Anti-CD137 (4-1BB) agonists also stimulated Eomes-dependent CD226 loss that limited the anti-tumor efficacy of this treatment. Thus, CD226 loss restrains CD8+ T cell function and limits the efficacy of cancer immunotherapy.

CD155 on Tumor Cells Drives Resistance to Immunotherapy by Inducing the Degradation of the Activating Receptor CD226 in CD8+ T Cells.

The activating receptor CD226 is expressed on lymphocytes, monocytes, and platelets and promotes anti-tumor immunity in pre-clinical models. Here, we examined the role of CD226 in the function of tumor-infiltrating lymphocytes (TILs) and resistance to immunotherapy. In murine tumors, a large proportion of CD8+ TILs had decreased surface expression of CD226 and exhibited features of dysfunction, whereas CD226hi TILs were highly functional. This correlation was seen also in TILs isolated from HNSCC patients. Mutation of CD226 at tyrosine 319 (Y319) led to increased CD226 surface expression, enhanced anti-tumor immunity and improved efficacy of immune checkpoint blockade (ICB). Mechanistically, tumor-derived CD155, the ligand for CD226, initiated phosphorylation of Y319 by Src kinases, thereby enabling ubiquitination of CD226 by CBL-B, internalization, and proteasomal degradation. In pre-treatment samples from melanoma patients, CD226+CD8+ T cells correlated with improved progression-free survival following ICB. Our findings argue for the development of therapies aimed at maintaining the expression of CD226.

The receptors CD96 and CD226 oppose each other in the regulation of natural killer cell functions.

CD96, CD226 (DNAM-1) and TIGIT belong to an emerging family of receptors that interact with nectin and nectin-like proteins. CD226 activates natural killer (NK) cell-mediated cytotoxicity, whereas TIGIT reportedly counterbalances CD226. In contrast, the role of CD96, which shares the ligand CD155 with CD226 and TIGIT, has remained unclear. In this study we found that CD96 competed with CD226 for CD155 binding and limited NK cell function by direct inhibition. As a result, Cd96(-/-) mice displayed hyperinflammatory responses to the bacterial product lipopolysaccharide (LPS) and resistance to carcinogenesis and experimental lung metastases. Our data provide the first description, to our knowledge, of the ability of CD96 to negatively control cytokine responses by NK cells. Blocking CD96 may have applications in pathologies in which NK cells are important.

NK cells with adhesion defects and reduced cytotoxic functions are associated with a poor prognosis in Multiple Myeloma.

The promising results obtained with immunotherapeutic approaches for multiple myeloma (MM) call for a better stratification of patients based on immune components. The most pressing being cytotoxic lymphocytes such as Natural Killer (NK) cells that are mandatory for MM surveillance and therapy. In this study, we performed a single cell RNA sequencing analysis of NK cells from 10 MM patients and 10 age/sex matched healthy donors (HD) that revealed important transcriptomic changes in NK cell landscape affecting both the bone marrow and peripheral blood compartment. The frequency of mature cytotoxic "CD56dim" NK cell subsets was reduced in MM patients at the advantage of late-stage NK cell subsets expressing NFB and IFN-I inflammatory signatures. These NK cell subsets accumulating in MM patients were characterized by a low CD16 and CD226 expression and poor cytotoxic functions. MM CD16/CD226Lo NK cells also had adhesion defects with reduced LFA-1 integrin activation and actin polymerization that may account for their limited effector functions in vitro. Finally, analysis of BM infiltrating NK cells in a retrospective cohort of 177 MM patients from the IFM 2009 trial demonstrated that a high frequency of NK cells and their low CD16 and CD226 expression were associated with a shorter overall survival. Thus, CD16/CD226Lo NK cells with reduced effector functions accumulate along MM development and negatively impact patients' clinical outcome. Given the growing interest in harnessing NK cells to treat myeloma, this improved knowledge around MM-associated NK cell dysfunction will stimulate the development of more efficient immunotherapeutic drugs against MM.

RAS/RAF landscape in monoclonal plasma cell conditions.

ABSTRACT: Multiple myeloma is characterized by a huge heterogeneity at the molecular level. The RAS/RAF pathway is the most frequently mutated, in ∼50% of the patients. However, these mutations are frequently subclonal, suggesting a secondary event. Because these genes are part of our routine next-generation sequencing panel, we analyzed >10 000 patients with different plasma cell disorders to describe the RAS/RAF landscape. In this large cohort of patients, almost 61% of the patients presented a RAS/RAF mutation at diagnosis or relapse, but much lower frequencies occurred in presymptomatic cases. Of note, the mutations were different from that observed in solid tumors (higher proportions of Q61 mutations). In 29 patients with 2 different mutations, we were able to perform single-cell sequencing, showing that in most cases, mutations occurred in different subclones, suggesting an ongoing mutational process. These findings suggest that the RAS/RAF pathway is not an attractive target, both on therapeutic and residual disease assessment points of view.

SAR442085, a novel anti-CD38 antibody with enhanced antitumor activity against multiple myeloma.

Anti-CD38 monoclonal antibodies (mAbs) represent a breakthrough in the treatment of multiple myeloma (MM), yet some patients fail to respond or progress quickly with this therapy, highlighting the need for novel approaches. In this study we compared the preclinical efficacy of SAR442085, a next-generation anti-CD38 mAb with enhanced affinity for activating Fcγ receptors (FcγR), with first-generation anti-CD38 mAb daratumumab and isatuximab. In surface plasmon resonance and cellular binding assays, we found that SAR442085 had higher binding affinity than daratumumab and isatuximab for FcγRIIa (CD32a) and FcγRIIIa (CD16a). SAR442085 also exhibited better in vitro antibody-dependent cellular cytotoxicity (ADCC) against a panel of MM cells expressing variable CD38 receptor densities including MM patients' primary plasma cells. The enhanced ADCC of SAR442085 was confirmed using NK-92 cells bearing low and high affinity FcγRIIIa (CD16a)-158F/V variants. Using MM patients' primary bone marrow cells, we confirmed that SAR442085 had an increased ability to engage FcγRIIIa, resulting in higher natural killer (NK) cell activation and degranulation against primary plasma cells than preexisting Fc wild-type anti-CD38 mAbs. Finally, using huFcgR transgenic mice that express human Fcγ receptors under the control of their human regulatory elements, we demonstrated that SAR442085 had higher NK cell-dependent in vivo antitumor efficacy and better survival than daratumumab and isatuximab against EL4 thymoma or VK*MYC myeloma cells overexpressing human CD38. These results highlight the preclinical efficacy of SAR442085 and support the current evaluation of this next-generation anti-CD38 antibody in phase I clinical development in patients with relapsed/refractory MM.

Cancer immunoediting and immune dysregulation in multiple myeloma.

Avoiding immune destruction is a hallmark of cancer. Over the past few years, significant advances have been made in understanding immune dysfunction and immunosuppression in multiple myeloma (MM), and various immunotherapeutic approaches have delivered improved clinical responses. However, it is still challenging to completely eliminate malignant plasma cells (PCs) and achieve complete cure. The interplay between the immune system and malignant PCs is implicated throughout all stages of PC dyscrasias, including asymptomatic states called monoclonal gammopathy of undetermined significance and smoldering myeloma. Although the immune system effectively eliminates malignant PCs, or at least induces functional dormancy at early stages, malignant PCs eventually evade immune elimination, leading to progression to active MM, in which dysfunctional effector lymphocytes, tumor-educated immunosuppressive cells, and soluble mediators coordinately act as a barrier for antimyeloma immunity. An in-depth understanding of this dynamic process, called cancer immunoediting, will provide important insights into the immunopathology of PC dyscrasias and MM immunotherapy. Moreover, a growing body of evidence suggests that, together with nonhematopoietic stromal cells, bone marrow (BM) immune cells with unique functions support the survival of normal and malignant PCs in the BM niche, highlighting the diverse roles of immune cells beyond antimyeloma immunity. Together, the immune system critically acts as a rheostat that fine-tunes the balance between dormancy and disease progression in PC dyscrasias.

TIGIT immune checkpoint blockade restores CD8+ T-cell immunity against multiple myeloma.

Immune-based therapies hold promise for the treatment of multiple myeloma (MM), but so far, immune checkpoint blockade targeting programmed cell death protein 1 has not proven effective as single agent in this disease. T-cell immunoglobulin and ITIM domains (TIGIT) is another immune checkpoint receptor known to negatively regulate T-cell functions. In this study, we investigated the therapeutic potential of TIGIT blockade to unleash immune responses against MM. We observed that, in both mice and humans, MM progression was associated with high levels of TIGIT expression on CD8+ T cells. TIGIT+ CD8+ T cells from MM patients exhibited a dysfunctional phenotype characterized by decreased proliferation and inability to produce cytokines in response to anti-CD3/CD28/CD2 or myeloma antigen stimulation. Moreover, when challenged with Vk*MYC mouse MM cells, TIGIT-deficient mice showed decreased serum monoclonal immunoglobulin protein levels associated with reduced tumor burden and prolonged survival, indicating that TIGIT limits antimyeloma immune responses. Importantly, blocking TIGIT using monoclonal antibodies increased the effector function of MM patient CD8+ T cells and suppressed MM development. Altogether our data provide evidence for an immune-inhibitory role of TIGIT in MM and support the development of TIGIT-blocking strategies for the treatment of MM patients.

Imprinting of Mesenchymal Stromal Cell Transcriptome Persists even after Treatment in Patients with Multiple Myeloma.

INTRODUCTION: Multiple myeloma (MM) is a B-cell neoplasm characterized by clonal expansion of malignant plasma cells (MM cells) in the bone-marrow (BM) compartment. BM mesenchymal stromal cells (MSC) from newly diagnosed MM patients were shown to be involved in MM pathogenesis and chemoresistance. The patients displayed a distinct transcriptome and were functionally different from healthy donors' (HD) MSC. Our aim was to determine whether MM-MSC also contributed to relapse. METHODS: We obtained and characterized patients' MSC samples at diagnosis, two years after intensive treatment, without relapse and at relapse. RESULTS: Transcriptomic analysis revealed differences in gene expression between HD and MM-MSC, whatever the stage of the disease. An easier differentiation towards adipogenesis at the expense of osteoblatogeneis was observed, even in patients displaying a complete response to treatment. Although their transcriptome was similar, we found that MSC from relapsed patients had an increased immunosuppressive ability, compared to those from patients in remission. CONCLUSION: We demonstrated that imprinting of MSC transcriptome demonstrated at diagnosis of MM, persisted even after the apparent disappearance of MM cells induced by treatment, suggesting the maintenance of a local context favorable to relapse.

NK cells require IL-28R for optimal in vivo activity.

Natural killer (NK) cells are naturally circulating innate lymphoid cells that protect against tumor initiation and metastasis and contribute to immunopathology during inflammation. The signals that prime NK cells are not completely understood, and, although the importance of IFN type I is well recognized, the role of type III IFN is comparatively very poorly studied. IL-28R-deficient mice were resistant to LPS and cecal ligation puncture-induced septic shock, and hallmark cytokines in these disease models were dysregulated in the absence of IL-28R. IL-28R-deficient mice were more sensitive to experimental tumor metastasis and carcinogen-induced tumor formation than WT mice, and additional blockade of interferon alpha/beta receptor 1 (IFNAR1), but not IFN-γ, further enhanced metastasis and tumor development. IL-28R-deficient mice were also more susceptible to growth of the NK cell-sensitive lymphoma, RMAs. Specific loss of IL-28R in NK cells transferred into lymphocyte-deficient mice resulted in reduced LPS-induced IFN-γ levels and enhanced tumor metastasis. Therefore, by using IL-28R-deficient mice, which are unable to signal type III IFN-λ, we demonstrate for the first time, to our knowledge, the ability of IFN-λ to directly regulate NK cell effector functions in vivo, alone and in the context of IFN-αß.

High endothelial venule blood vessels for tumor-infiltrating lymphocytes are associated with lymphotoxin ß-producing dendritic cells in human breast cancer.

Blood vessels and tumor angiogenesis are generally associated with tumor growth and poor clinical outcome of cancer patients. However, we recently discovered that some blood vessels present within the tumor microenvironment can be associated with favorable prognosis. These vessels, designated tumor high endothelial venules (HEVs), appear to facilitate tumor destruction by allowing high levels of lymphocyte infiltration into tumors. In this study, we investigated the mechanisms regulating HEV blood vessels in human breast cancer. We found that lymphotoxin ß was overexpressed in tumors containing high densities of HEVs (HEV(high)) and correlated to DC-LAMP, a marker of mature DCs. DCs were the main producers of lymphotoxin ß in freshly resected HEV(high) breast tumor samples, and the density of DC-LAMP(+) DCs clusters was strongly correlated with the density of tumor HEVs, T and B cell infiltration, and favorable clinical outcome in a retrospective cohort of 146 primary invasive breast cancer patients. Densities of tumor HEVs and DC-LAMP(+) DCs were strongly reduced during breast cancer progression from in situ carcinoma to invasive carcinoma, suggesting that loss of tumor HEVs is a critical step during breast cancer progression. Finally, an increase in the infiltration of regulatory T cells was observed in HEV(high) breast tumors, indicating that tumor HEVs can develop in the presence of regulatory T cells. Together, our results support a key role for DCs and DC-derived lymphotoxin in the formation of tumor HEVs. These findings are important because novel therapeutic strategies based on the modulation of tumor HEVs could have a major impact on clinical outcome of cancer patients.

DNAM-1 control of natural killer cells functions through nectin and nectin-like proteins.

Natural killer (NK) cells represent key innate immune cells that restrain viral infection and malignant transformation and help mount an adaptive immune response. To perform such complicated tasks, NK cells express a wide set of inhibitory and activating receptors that alert them against cellular stress without damaging healthy cells. A new family of receptors that recognize nectin and nectin-like molecules has recently emerged as a critical regulator of NK cell functions. The most famous member of this family, DNAX accessory molecule (DNAM-1, CD226), is an adhesion molecule that control NK cell cytotoxicity and interferon-γ production against a wide range of cancer and infected cells. Its ligands CD112 and CD155 have been described in different pathological conditions, and recent evidence indicates that their expression is regulated by cellular stress. Additional receptors have been shown to bind DNAM-1 ligands and modulate NK cell functions bringing another level of complexity. These include CD96 (TACTILE) and TIGIT (WUCAM, VSTM3). Here, we review the role of DNAM-1, TIGIT and CD96 in NK cell biology summarizing the recent advances made on the role of these receptors in various pathologies, such as cancer, viral infections and autoimmunity.

Stimulated γδ T cells increase the in vivo efficacy of trastuzumab in HER-2+ breast cancer.

One fourth of women with HER-2(+) metastatic breast carcinoma are treated with a combination regimen with trastuzumab, but the frequent resistance to this Ab requires definition of new means to improve its bioactivity. The mechanisms of action of trastuzumab involve several pathways including Ab-dependent cellular cytotoxicity. Because human γδ T lymphocytes mediate Ab-dependent cellular cytotoxicity and can be activated further by phosphoantigens, these cells are prone to improve the efficacy of Abs, as recently demonstrated for CD20(+) B cell lymphomas. Whether this concept applies as well with carcinomas remained to be demonstrated in vivo, however. In this study, we asked whether a combination of trastuzumab and phosphoantigen-stimulated γδ lymphocytes increases the efficacy of trastuzumab against HER-2(+) breast carcinoma cell lines in vivo. We report that repeated infusions of this combination had a better efficacy than that of trastuzumab alone against HER-2(+) mammary carcinoma xenografts in mice. In these models, reduction of tumor growth was observed together with trastuzumab opsonization of HER-2(+) cells and tumor infiltration by γδ lymphocytes. In addition in humans, the mammary carcinomas of 27 of 30 patients showed significant γδ T cell infiltrates. Altogether, these findings indicate that combination of trastuzumab and stimulated γδ cells represents a new strategy to improve the efficacy of Herceptin (trastuzumab) in HER-2(+) breast cancer.

Phosphoantigens overcome human TCRVgamma9+ gammadelta Cell immunosuppression by TGF-beta: relevance for cancer immunotherapy.

Human gammadelta cells expressing TCRVgamma9 are HLA-unrestricted CTLs with high relevance for cancer immunotherapy. Many tumor cell types produce TGF-beta, however, a cytokine strongly immunosuppressive for conventional T CD4, CD8, and NK cells. Whether TGF-beta also inhibits TCRVgamma9+ lymphocytes was unknown. Because phosphoantigens (PAgs), such as bromohydrin pyrophosphate, selectively activate the antitumor functions of TCRVgamma9+ T cells, in this study, we investigated whether TGF-beta modulates these functions. We report that TGF-beta does not block activation of TCRVgamma9+ T cells but inhibits their PAg/IL-2-induced proliferation and maturation into effector cells and finally reduces the cytotoxic activity of these gammadelta T cells when exposed to lymphoma target cells. TGF-beta did not bias their differentiation pattern toward gammadelta Th17 or gammadelta regulatory T cells. Nevertheless, increasing doses of PAg stimulus countered TGF-beta inhibition. So, although TGF-beta impairs TCRVgamma9+ gammadelta cells like other cytolytic lymphocytes, PAg alone or combined to therapeutic mAb has the ability to bypass its immunosuppressive activity.

How tumors might withstand γδ T-cell attack.

Several clinical trials are currently assessing the therapeutic activity of human TCRVγ9Vδ2(+) lymphocytes in cancer. Growing tumors usually follow a triphasic "Elimination, Equilibrium, Escape" evolution in patients. Thus, at diagnostic, most tumors have already developed some means to escape to immune protection. We review here the conventional immunoescape mechanisms which might also protect against cytolytic TCRVγ9Vδ2(+) lymphocytes activated by phosphoantigens. Neutralization of these deleterious processes might prove highly valuable to improve the efficacy of ongoing γδ cell-based cancer immunotherapies.

Toll-like receptor 4 selective inhibition in medullar microenvironment alters multiple myeloma cell growth.

Bone marrow (BM) mesenchymal stromal cells (MSCs) are abnormal in multiple myeloma (MM) and play a critical role by promoting growth, survival, and drug resistance of MM cells. We observed higher Toll-like receptor 4 (TLR4) gene expression in MM MSCs than in MSCs from healthy donors. At the clinical level, we highlighted that TLR4 expression in MM MSCs evolves in parallel with the disease stage. Thus, we reasoned that the TLR4 axis is pivotal in MM by increasing the protumor activity of MSCs. Challenging primary MSCs with TLR4 agonists increased the expression of CD54 and interleukin-6 (IL-6), 2 factors directly implicated in MM MSC-MM cell crosstalk. Then, we evaluated the therapeutic efficacy of a TLR4 antagonist combined or not with conventional treatment in vitro with MSC-MM cell coculture and in vivo with the Vk*MYC mouse model. Selective inhibition of TLR4 specifically reduced the MM MSC ability to support the growth of MM cells in an IL-6-dependent manner and delayed the development of MM in the Vk*MYC mouse model by altering the early disease phase in vivo. For the first time, we demonstrate that specific targeting of the pathological BM microenvironment via TLR4 signaling could be an innovative approach to alter MM pathology development.

Hospicells derived from ovarian cancer stroma inhibit T-cell immune responses.

With metastatic disease at diagnosis for 70% of patients, ovarian cancer represents the most lethal gynecological malignancy. Ovarian carcinomas are aggressive malignancies that can evade immune surveillance and frequently develop into metastases. The tumor microenvironment is decisive for preventing immune attack but, in the case of ovarian carcinoma, the mechanisms are unclear. We recently isolated a novel type of stromal cell from the ascitis of patients with ovarian carcinoma that interacts with epithelial ovarian cancers conferring them chemoresistance. These cells, called Hospicells, have the cell surface markers CD9, CD10, CD29, CD146 and CD166. Here, we investigated whether Hospicells also have immunomodulatory functions that might interfere with immunity to cancer. We report that Hospicells inhibit the proliferation of human CD4(+), CD8(+) and Vgamma9Vdelta2 T cells in vitro and the production of cytokines by these immune cells. The immunosuppression of CD4(+) T cells is independent of direct contact with the Hospicells and is mainly due to nitric oxide produced by the inducible nitric oxide synthase and to products of the tryptophan degradation by indoleamine 2,3-dioxygenase. We proposed that Hospicells in the microenvironment of the tumor mediate immunosuppression of T cells and thus allow ovarian cancers to evade immune surveillance. Targeting of Hospicells could be an alternative to strong chemotherapy through the recovery of immune responses against tumor cells.

A regulatory cross-talk between Vgamma9Vdelta2 T lymphocytes and mesenchymal stem cells.

The physiological functions of human TCRVgamma9Vdelta2(+) gammadelta lymphocytes reactive to non-peptide phosphoantigens contribute to cancer immunosurveillance and immunotherapy. However, their regulation by mesenchymal stem cells (MSC), multipotent and immunomodulatory progenitor cells able to infiltrate tumors, has not been investigated so far. By analyzing freshly isolated TCRVgamma9Vdelta2(+) lymphocytes and primary cell lines stimulated with synthetic phosphoantigen or B-cell lymphoma cell lines in the presence of MSC, we demonstrated that MSC were potent suppressors of gammadelta-cell proliferation, cytokine production and cytolytic responses in vitro. This inhibition was mediated by the COX-2-dependent production of prostaglandin E2 (PGE(2)) and by MSC through EP2 and EP4 inhibitory receptors expressed by Vgamma9Vdelta2 T lymphocytes. COX-2 expression and PGE(2) production by MSC were not constitutive, but were induced by IFN-gamma and TNF-alpha secreted by activated Vgamma9Vdelta2 T cells. This regulatory cross-talk between MSC and Vgamma9Vdelta2 T lymphocytes involving PGE(2) could be of importance for the antitumor and antimicrobial activities of gammadelta T cells.

Human peripheral blood DNAM-1neg NK cells are a terminally differentiated subset with limited effector functions.

Natural killer (NK) cells are a heterogeneous population of innate lymphocytes whose potent anticancer properties make them ideal candidates for cellular therapeutic application. However, our lack of understanding of the role of NK cell diversity in antitumor responses has hindered advances in this area. In this study, we describe a new CD56dim NK cell subset characterized by the lack of expression of DNAX accessory molecule-1 (DNAM-1). Compared with CD56bright and CD56dimDNAM-1pos NK cell subsets, CD56dimDNAM-1neg NK cells displayed reduced motility, poor proliferation, lower production of interferon-γ, and limited killing capacities. Soluble factors secreted by CD56dimDNAM-1neg NK cells impaired CD56dimDNAM-1pos NK cell-mediated killing, indicating a potential inhibitory role for the CD56dimDNAM-1neg NK cell subset. Transcriptome analysis revealed that CD56dimDNAM-1neg NK cells constitute a new mature NK cell subset with a specific gene signature. Upon in vitro cytokine stimulation, CD56dimDNAM-1neg NK cells were found to differentiate from CD56dimDNAM-1pos NK cells. Finally, we report a dysregulation of NK cell subsets in the blood of patients diagnosed with Hodgkin lymphoma and diffuse large B-cell lymphoma, characterized by decreased CD56dimDNAM-1pos/CD56dimDNAM-1neg NK cell ratios and reduced cytotoxic activity of CD56dimDNAM-1pos NK cells. Altogether, our data offer a better understanding of human peripheral blood NK cell populations and have important clinical implications for the design of NK cell-targeting therapies.