Coordinated regulation of NK receptor expression in the maturing human immune system

Inflammation mechanism and anti-inflammatory therapy of dry eye

Dry eye is a widespread chronic inflammatory disease that causes fatigue, tingling, burning, and other symptoms. Dry eye is attributed to rheumatic diseases, diabetes, hormone disorders, and contact lenses, which activate inflammatory pathways: mitogen-activated protein kinases (MAPK) and nuclear factor-B (NF-κB), promote macrophage inflammatory cell and T cell activation, and inflammation factors. Clinicians use a combination of anti-inflammatory drugs to manage different symptoms of dry eye; some of these anti-inflammatory drugs are being developed. This review introduces the dry eye inflammation mechanisms and the involved inflammatory factors. We also elucidate the anti-inflammatory drug mechanism and the detection limits.

Cord blood derived NK cells activated in counter with tumor cells

NK cells are initially known for their ability to kill tumor cells with no prior sensitization. Production of mature and long lasting NK cells from Umbilical Cord Blood (UCB) by using cytokines could be a promising method for immunotherapy. NK cells were generated from cord blood cells using IL2, IL7, and IL15 cytokines and measured expression of CD57 and NKp46 markers. Afterward, their capacity in the elimination of malignant cells (Reh cell line) was evaluated by assessment of interferon-γ (as cytokine production sign) and CD107-a expression (as cytotoxic function symptom) using flow cytometry. Our results showed efficient NKp46 + , and CD57 + NK cells generated on day 14. Also, expression of CD107-a and IFN-γ following co-culture with Reh cell lines significantly increased in comparison to the control. Taken together, we have reported one of the best culture conditions for the generation of CD57 + NK cells with on feeder cells and showed appropriate capacity in counter reh cell lines as a target.

The central role of DNA damage in immunosenescence

Ageing is the biggest risk factor for the development of multiple chronic diseases as well as increased infection susceptibility and severity of diseases such as influenza and COVID-19. This increased disease risk is linked to changes in immune function during ageing termed immunosenescence. Age-related loss of immune function, particularly in adaptive responses against pathogens and immunosurveillance against cancer, is accompanied by a paradoxical gain of function of some aspects of immunity such as elevated inflammation and increased incidence of autoimmunity. Of the many factors that contribute to immunosenescence, DNA damage is emerging as a key candidate. In this review, we discuss the evidence supporting the hypothesis that DNA damage may be a central driver of immunosenescence through senescence of both immune cells and cells of non-haematopoietic lineages. We explore why DNA damage accumulates during ageing in a major cell type, T cells, and how this may drive age-related immune dysfunction. We further propose that existing immunosenescence interventions may act, at least in part, by mitigating DNA damage and restoring DNA repair processes (which we term "genoprotection"). As such, we propose additional treatments on the basis of their evidence for genoprotection, and further suggest that this approach may provide a viable therapeutic strategy for improving immunity in older people.

Anti-Inflammatories in the Treatment of Dry Eye Disease: A Review

Inflammation is an important driver of dry eye disease (DED) pathogenesis. An initial insult that results in the loss of tear film homeostasis can initiate a nonspecific innate immune response that leads to a chronic and self-sustaining inflammation of the ocular surface, which results in classic symptoms of dry eye. This initial response is followed by a more prolonged adaptive immune response, which can perpetuate and aggravate inflammation and result in a vicious cycle of chronic inflammatory DED. Effective anti-inflammatory therapies can help patients exit this cycle, and effective diagnosis of inflammatory DED and selection of the most appropriate treatment are therefore key to successful DED management and treatment. This review explores the cellular and molecular mechanisms of the immune and inflammatory components of DED, and examines the evidence base for the use of currently available topical treatment options. These agents include topical steroid therapy, calcineurin inhibitors, T cell integrin antagonists, antibiotics, autologous serum/plasma therapy, and omega-3 fatty acid dietary supplements.

High Frequencies of Phenotypically and Functionally Senescent and Exhausted CD56+CD57+PD-1+ Natural Killer Cells, SARS-CoV-2-Specific Memory CD4+ and CD8+ T cells Associated with Severe Disease in Unvaccinated COVID-19 Patients

Unvaccinated COVID-19 patients display a large spectrum of symptoms, ranging from asymptomatic to severe symptoms, the latter even causing death. Distinct Natural killer (NK) and CD4+ and CD8+ T cells immune responses are generated in COVID-19 patients. However, the phenotype and functional characteristics of NK cells and T-cells associated with COVID-19 pathogenesis versus protection remain to be elucidated. In this study, we compared the phenotype and function of NK cells SARS-CoV-2-specific CD4+ and CD8+ T cells in unvaccinated symptomatic (SYMP) and unvaccinated asymptomatic (ASYMP) COVID-19 patients. The expression of senescent CD57 marker, CD45RA/CCR7differentiation status, exhaustion PD-1 marker, activation of HLA-DR, and CD38 markers were assessed on NK and T cells from SARS-CoV-2 positive SYMP patients, ASYMP patients, and Healthy Donors (HD) using multicolor flow cytometry. We detected significant increases in the expression levels of both exhaustion and senescence markers on NK and T cells from SYMP patients compared to ASYMP patients and HD controls. In SYMP COVID-19 patients, the T cell compartment displays several alterations involving naive, central memory, effector memory, and terminally differentiated T cells. The senescence CD57 marker was highly expressed on CD8+ TEM cells and CD8+ TEMRA cells. Moreover, we detected significant increases in the levels of pro-inflammatory TNF-α, IFN-γ, IL-6, IL-8, and IL-17 cytokines from SYMP COVID-19 patients, compared to ASYMP COVID-19 patients and HD controls. The findings suggest exhaustion and senescence in both NK and T cell compartment is associated with severe disease in critically ill COVID-19 patients.

Current Advances in Mechanisms and Treatment of Dry Eye Disease: Toward Anti-inflammatory and Immunomodulatory Therapy and Traditional Chinese Medicine

Dry eye is currently one of the most common ocular surface disease. It can lead to ocular discomfort and even cause visual impairment, which greatly affects the work and quality of life of patients. With the increasing incidence of dry eye disease (DED) in recent years, the disease is receiving more and more attention, and has become one of the hot research fields in ophthalmology research. Recently, with the in-depth research on the etiology, pathogenesis and treatment of DED, it has been shown that defects in immune regulation is one of the main pathological mechanisms of DED. Since the non-specific and specific immune response of the ocular surface are jointly regulated, a variety of immune cells and inflammatory factors are involved in the development of DED. The conventional treatment of DED is the application of artificial tears for lubricating the ocular surface. However, for moderate-to-severe DED, treatment with anti-inflammatory drugs is necessary. In this review, the immunomodulatory mechanisms of DED and the latest research progress of its related treatments including Chinese medicine will be discussed.

LIR-1 educates expanded human NK cells and defines a unique antitumor NK cell subset with potent antibody-dependent cellular cytotoxicity

Objective

KIR and NKG2A receptors educate human NK cells to stay responsive to cells with diminished HLA class I. Here, we addressed whether the HLA class I-binding receptor LIR-1 (LILRB1/ILT2/CD85j), which is widely expressed on human NK cells, can mediate education and contribute to antitumor functions of NK cells.

Methods

Healthy donor NK cells either unstimulated, overnight cytokine-activated or ex vivo-expanded were used to target human cell lines. Phenotype and function were analysed using flow cytometry and ⁵¹Cr-release assays.

Results

We found that the inhibitory receptor LIR-1 can mediate NK cell education under specific conditions. This novel finding was exclusive to expanded NK cells and further characterisation of the cells revealed high expression of granzyme B and DNAM-1, which both previously have been linked to NK cell education. Corroborating the rheostat education model, LIR-1 co-expression with an educating KIR further increased the responsiveness of expanded NK cells. Inversely, antibody masking of LIR-1 decreased the responsiveness. LIR-1⁺ expanded NK cells displayed high intrinsic ADCC that, in contrast to KIR and NKG2A, was not inhibited by HLA class I.

Conclusion

These findings identify a unique NK cell subset attractive for adoptive cell therapy to treat cancer. Given that LIR-1 binds most HLA class I molecules, this subset may be explored in both autologous and allogeneic settings to innately reject HLA class I^- tumor cells as well as HLA class I⁺ target cells when combined with antitumor antibodies. Further studies are warranted to address the potential of this subset in vivo.

Food Intolerance: The Role of Histamine

Histamine is a natural amine derived from L-histidine. Although it seems that our knowledge about this molecule is wide and diverse, the importance of histamine in many regulatory processes is still enigmatic. The interplay between different types of histamine receptors and the compound may cause ample effects, including histamine intoxication and so-called histamine intolerance or non-allergic food intolerance, leading to disturbances in immune regulation, manifestation of gastroenterological symptoms, and neurological diseases. Most cases of clinical manifestations of histamine intolerance are non-specific due to tissue-specific distribution of different histamine receptors and the lack of reproducible and reliable diagnostic markers. The diagnosis of histamine intolerance is fraught with difficulties, in addition to challenges related to the selection of a proper treatment strategy, the regular course of recovery, and reduced amelioration of chronic symptoms due to inappropriate treatment prescription. Here, we reviewed a history of histamine uptake starting from the current knowledge about its degradation and the prevalence of histamine precursors in daily food, and continuing with the receptor interactions after entering and the impacts on the immune, central nervous, and gastrointestinal systems. The purpose of this review is to build an extraordinarily specific method of histamine cycle assessment in regard to non-allergic intolerance and its possible dire consequences that can be suffered.

Experimental Pharmacotherapy for Dry Eye Disease: A Review

Dry eye disease (DED) is a complex multifactorial disease showing heterogenous symptoms, including dryness, photophobia, ocular discomfort, irritation and burning but also pain. These symptoms can affect visual function leading to restrictions in daily life activities and reduction in work productivity with a consequently high impact on quality of life. Several pathological mechanisms contribute to the disease: evaporative water loss leads to impairment and loss of tear homeostasis inducing either directly or indirectly to inflammation, in a self-perpetuating vicious cycle. Dysregulated ocular immune responses result in ocular surface damage, which further contributes to DED pathogenesis. Currently, DED treatment is based on a flexible stepwise approach to identify the most beneficial intervention. Although most of the available treatments may control to a certain extent some signs and symptoms of DED, they show significant limitations and do not completely address the needs of patients suffering from DED. This review provides an overview of the emerging experimental therapies for DED. Several promising therapeutic strategies are under development with the aim of dampening inflammation and restoring the homeostasis of the ocular surface microenvironment. Results from early phase clinical trials, testing the effects of EnaC blockers, TRPM8 agonist or mesenchymal stem cells in DED patients, are especially awaited to demonstrate their therapeutic value for the treatment of DED. Moreover, the most advanced experimental strategies in the pipeline for DED, tivanisiran, IL-1R antagonist EBI-005 and SkQ1, are being tested in Phase III clinical trials, still ongoing. Nevertheless, although promising results, further studies are still needed to confirm efficacy and safety of the new emerging therapies for DED.

SIV-induced terminally differentiated adaptive NK cells in lymph nodes associated with enhanced MHC-E restricted activity

Natural killer (NK) cells play a critical understudied role during HIV infection in tissues. In a natural host of SIV, the African green monkey (AGM), NK cells mediate a strong control of SIVagm infection in secondary lymphoid tissues. We demonstrate that SIVagm infection induces the expansion of terminally differentiated NKG2a^low NK cells in secondary lymphoid organs displaying an adaptive transcriptional profile and increased MHC-E-restricted cytotoxicity in response to SIV Env peptides while expressing little IFN-γ. Such NK cell differentiation was lacking in SIVmac-infected macaques. Adaptive NK cells displayed no increased NKG2C expression. This study reveals a previously unknown profile of NK cell adaptation to a viral infection, thus accelerating strategies toward NK-cell directed therapies and viral control in tissues.

Dual role of B7-H6 as a novel prognostic marker in hepatocellular carcinoma

B7 homolog 6 (B7-H6), a new member of the B7 family, is identified as an activating ligand for cytotoxicity triggering receptor 3 (NKp30) expressing on natural killer cells. The purpose of this study was to investigate the clinical significance of B7-H6 in hepatocellular carcinoma (HCC). We evaluated B7-H6 expression by immunohistochemistry in a cohort of 90 HCC tumors with clinical follow-up, the potential relationship between the B7-H6 expression and the clinicopathological characteristics of HCC patients was also analyzed. Stable B7-H6 knockdown in hepatoma cell line was established to explore the function and mechanism of B7-H6 in HCC. This study showed that high expression of B7-H6 was significantly associated with smaller tumor size, single tumor number in HCC, but no significant association was found between B7-H6 overexpression and other clinicopathological parameters. Moreover, Kaplan-Meier survival analysis showed that high expression of B7-H6 was significantly correlated with better survival of HCC patients. Knockdown of B7-H6 inhibited tumor cell proliferation and induced cell apoptosis. However, it also impaired the sensitivity of tumor cells to NK-mediated lysis together with significantly decreased degranulation and IFN-γ release of NK cells. These results indicated that B7-H6 has a dual role in HCC. It could be an independent indicator for better survival of HCC and maybe a potential target for future cancer treatment.

Targeting Inflammation and Immunosenescence to Improve Vaccine Responses in the Elderly

One of the most appreciated consequences of immunosenescence is an impaired response to vaccines with advanced age. While most studies report impaired antibody responses in older adults as a correlate of vaccine efficacy, it is now widely appreciated that this may fail to identify important changes occurring in the immune system with age that may affect vaccine efficacy. The impact of immunosenescence on vaccination goes beyond the defects on antibody responses as T cell-mediated responses are reshaped during aging and certainly affect vaccination. Likewise, age-related changes in the innate immune system may have important consequences on antigen presentation and priming of adaptive immune responses. Importantly, a low-level chronic inflammatory status known as inflammaging has been shown to inhibit immune responses to vaccination and pharmacological strategies aiming at blocking baseline inflammation can be potentially used to boost vaccine responses. Yet current strategies aiming at improving immunogenicity in the elderly have mainly focused on the use of adjuvants to promote local inflammation. More research is needed to understand the role of inflammation in vaccine responses and to reconcile these seemingly paradoxical observations. Alternative approaches to improve vaccine responses in the elderly include the use of higher vaccine doses or alternative routes of vaccination showing only limited benefits. This review will explore novel targets and potential new strategies for enhancing vaccine responses in older adults, including the use of anti-inflammatory drugs and immunomodulators.

Senescence blurs the line between innate and adaptive immune cells

In Covre et al. and Pereira et al., the authors demonstrate the parallels between senescent NK cells and senescent CD8 T cells, and formalise the mechanism by which senescent CD8 T cells become more NK cell-like, through the action of sestrins.

TGF-β and IL-15 Synergize through MAPK Pathways to Drive the Conversion of Human NK Cells to an Innate Lymphoid Cell 1-like Phenotype

Circulating NK cells are known to convert to a type 1 innate lymphoid cell (ILC1)-like phenotype in response to TGF-β exposure. However, the precise cellular changes defining this process as well as the downstream signaling pathways guiding it remain poorly defined, particularly in humans. We used mass cytometry by time-of-flight (CyTOF) to model this phenotypic shift in vitro and identify a synergistic activity of TGF-β and IL-15 in this cellular conversion. CyTOF profiling identified substantial heterogeneity in the propensity of NK cells to adopt an ILC1-like phenotype in culture, characterized by the step-wise acquisition of various markers, including CD69, CD9, CD103, and CD49a. Activating and inhibitory receptors, including NKG2A, NKG2D, KIR2DL1, KIR3DL1, NKp30, NKp44, and NKp46, were all found to be upregulated exclusively on the cellular subsets that converted most readily in response to TGF-β. An assessment of downstream TGF-β signaling identified TAK1-mediated activation of p38 MAPK as the critical pathway driving conversion. IL-15 enhanced TGF-β-mediated conversion through Ras:RAC1 signaling as well as via the activation of MEK/ERK. Interestingly, the adoption of an ILC1-like phenotype was independent of the effect of IL-15 or TGF-β on mTOR, as the culture of NK cells in the presence of mTOR inhibitors, such as rapamycin or torin1, had minimal impact on the degree of conversion. In conclusion, we have used in vitro human culture systems and CyTOF to define the conversion of circulating NK cells to an ILC1-like phenotype and have clarified the pathways responsible for this process.

The Immunological Basis of Dry Eye Disease and Current Topical Treatment Options

Homeostasis of the lacrimal functional unit is needed to ensure a well-regulated ocular immune response comprising innate and adaptive phases. When the ocular immune system is excessively stimulated and/or immunoregulatory mechanisms are disrupted, the balance between innate and adaptive phases is dysregulated and chronic ocular surface inflammation can result, leading to chronic dry eye disease (DED). According to the Tear Film and Ocular Surface Society Dry Eye Workshop II definition, DED is a multifactorial disorder of the ocular surface characterized by impairment and loss of tear homeostasis (hyperosmolarity), ocular discomfort or pain, and neurosensory abnormalities. Dysregulated ocular immune responses result in ocular surface damage, which is a further contributing factor to DED pathology. Several therapeutics are available to break the vicious circle of DED and prevent chronic disease and progression, including immunosuppressive agents (steroids) and immunomodulators (cyclosporine and lifitegrast). Given the chronic inflammatory nature of DED, each of these agents is commonly used in clinical practice. In this study, we review the immunopathology of DED and the molecular and cellular actions of current topical DED therapeutics to inform clinical decision making.

Distinct Human NK Cell Phenotypes and Functional Responses to Mycobacterium tuberculosis in Adults From TB Endemic and Non-endemic Regions

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB), which leads to an estimated 1. 5 million deaths worldwide each year. Although the immune correlates of protection against Mtb infection and TB disease have not been well-defined, natural killer (NK) cells are increasingly recognized as a key component of the innate immune response to Mtb and as a link between innate and adaptive immunity. In this study, we evaluated NK cell phenotypic and functional profiles in QuantiFERON-TB (QFT)⁺ and QFT⁻ adults in a TB endemic setting in Kisumu, Kenya, and compared their NK cell responses to those of Mtb-naïve healthy adult controls in the U.S. We used flow cytometry to define the phenotypic profile of NK cells and identified distinct CD56^dim NK cell phenotypes that differentiated the Kenyan and U.S. groups. Additionally, among Kenyan participants, NK cells from QFT⁺ individuals with latent Mtb infection (LTBI) were characterized by significant downregulation of the natural cytotoxicity receptor NKp46 and the inhibitory receptor TIGIT, compared with QFT⁻ individuals. Moreover, the distinct CD56^dim phenotypic profiles in Kenyan individuals correlated with dampened NK cell responses to tumor cells and diminished activation, degranulation, and cytokine production following stimulation with Mtb antigens, compared with Mtb-naïve U.S. healthy adult controls. Taken together, these data provide evidence that the phenotypic and functional profiles of NK cells are modified in TB endemic settings and will inform future studies aimed at defining NK cell-mediated immune correlates that may be protective against acquisition of Mtb infection and progression to TB disease.

Activatory Receptor NKp30 Predicts NK Cell Activation During Controlled Human Malaria Infection

Natural killer (NK) cells are known to be activated during malaria infection, exhibiting both cytokine production and cytotoxic functions. However, NK cells are heterogeneous in their expression of surface activatory and inhibitory receptors which may influence their response to malaria parasites. Here, we studied the surface marker profile and activation dynamics of NK cells during a Controlled Human Malaria Infection in 12 healthy volunteers. Although there was significant inter-patient variability in timing and magnitude of NK cell activation, we found a consistent and strong increase in expression of the activatory receptor NKp30. Moreover, high baseline NKp30 expression was associated with NK cell activation at lower parasite densities. Our data suggest that NKp30 expression may influence the NK cell response to P. falciparum, explaining inter-patient heterogeneity and suggesting a functional role for this receptor in malaria.

Pregnancy-Induced Alterations in NK Cell Phenotype and Function

Pregnant women are particularly susceptible to complications of influenza A virus infection, which may result from pregnancy-induced changes in the function of immune cells, including natural killer (NK) cells. To better understand NK cell function during pregnancy, we assessed the ability of the two main subsets of NK cells, CD56^dim, and CD56^bright NK cells, to respond to influenza-virus infected cells and tumor cells. During pregnancy, CD56^dim and CD56^bright NK cells displayed enhanced functional responses to both infected and tumor cells, with increased expression of degranulation markers and elevated frequency of NK cells producing IFN-γ. To better understand the mechanisms driving this enhanced function, we profiled CD56^dim and CD56^bright NK cells from pregnant and non-pregnant women using mass cytometry. NK cells from pregnant women displayed significantly increased expression of several functional and activation markers such as CD38 on both subsets and NKp46 on CD56^dim NK cells. NK cells also displayed diminished expression of the chemokine receptor CXCR3 during pregnancy. Overall, these data demonstrate that functional and phenotypic shifts occur in NK cells during pregnancy that can influence the magnitude of the immune response to both infections and tumors.

Phenotypic Evidence of T Cell Exhaustion and Senescence During Symptomatic Plasmodium falciparum Malaria

T cells play significant roles during Plasmodium falciparum infections. Their regulation of the immune response in symptomatic children with malaria has been deemed necessary to prevent immune associated pathology. In this study, we phenotypically characterized the expression of T cell inhibitory(PD-1, CTLA-4) and senescent markers (CD28(-), CD57) from children with symptomatic malaria, asymptomatic malaria and healthy controls using flow cytometry. We observed increased expression of T cell exhaustion and senescence markers in the symptomatic children compared to the asymptomatic and healthy controls. T cell senescence markers were more highly expressed on CD8 T cells than on CD4 T cells. Asymptomatically infected children had comparable levels of these markers with healthy controls except for CD8+ PD-1+ T cells which were significantly elevated in the asymptomatic children. Also, using multivariate regression analysis, CTLA-4 was the only marker that could predict parasitaemia level. The results suggest that the upregulation of immune exhaustion and senescence markers during symptomatic malaria may affect the effector function of T cells leading to inefficient clearance of parasites, hence the inability to develop sterile immunity to malaria.

Natural Killer Cells in Cancer Immunotherapy

Natural killer (NK) cells have evolved to complement T and B cells in host defense against pathogens and cancer. They recognize infected cells and tumors using a sophisticated array of activating, costimulatory, and inhibitory receptors that are expressed on NK cell subsets to create extensive functional diversity. NK cells can be targeted to kill with exquisite antigen specificity by antibody-dependent cellular cytotoxicity. NK and T cells share many of the costimulatory and inhibitory receptors that are currently under evaluation in the clinic for cancer immunotherapy. As with T cells, genetic engineering is being employed to modify NK cells to specifically target them to tumors and to enhance their effector functions. As the selective pressures exerted by immunotherapies to augment CD8+T cell responses may result in loss of MHC class I, NK cells may provide an important fail-safe to eliminate these tumors by their capacity to eliminate tumors that are “missing self.”

Expression of a Recombinant High Affinity IgG Fc Receptor by Engineered NK Cells as a Docking Platform for Therapeutic mAbs to Target Cancer Cells

Anti-tumor mAbs are the most widely used and characterized cancer immunotherapy. Despite having a significant impact on some malignancies, most cancer patients respond poorly or develop resistance to this therapy. A known mechanism of action of these therapeutic mAbs is antibody-dependent cell-mediated cytotoxicity (ADCC), a key effector function of human NK cells. CD16A on human NK cells has an exclusive role in binding to tumor-bound IgG antibodies. Though CD16A is a potent activating receptor, it is also a low affinity IgG Fc receptor (FcγR) that undergoes a rapid downregulation in expression by a proteolytic process involving ADAM17 upon NK cell activation. These regulatory processes are likely to limit the efficacy of tumor-targeting therapeutic mAbs in the tumor environment. We sought to enhance NK cell binding to anti-tumor mAbs by engineering these cells with a recombinant FcγR consisting of the extracellular region of CD64, the highest affinity FcγR expressed by leukocytes, and the transmembrane and cytoplasmic regions of CD16A. This novel recombinant FcγR (CD64/16A) was expressed in the human NK cell line NK92 and in induced pluripotent stem cells from which primary NK cells were derived. CD64/16A lacked the ADAM17 cleavage region in CD16A and it was not rapidly downregulated in expression following NK cell activation during ADCC. CD64/16A on NK cells facilitated conjugation to antibody-treated tumor cells, ADCC, and cytokine production, demonstrating functional activity by its two components. Unlike NK cells expressing CD16A, CD64/16A captured soluble therapeutic mAbs and the modified NK cells mediated tumor cell killing. Hence, CD64/16A could potentially be used as a docking platform on engineered NK cells for therapeutic mAbs and IgG Fc chimeric proteins, allowing for switchable targeting elements and a novel cancer cellular therapy.

Signatures of CD8+ T cell dysfunction in AML patients and their reversibility with response to chemotherapy

BACKGROUND

Our understanding of phenotypic and functional signatures of CD8+ T cell dysfunction in acute myeloid leukemia (AML) is limited. Deciphering these deranged T cell functional states and how they are impacted by induction chemotherapy is essential for incorporation of novel immune-based strategies to restore and maintain antileukemia immunity.

METHODS

We utilized high-dimensional immunophenotyping, gene expression, and functional studies to characterize peripheral blood and bone marrow CD8+ T cells in 72 AML patients at diagnosis and after induction chemotherapy.

RESULTS

Our data suggest that multiple aspects of deranged T cell function are operative in AML at diagnosis, with exhaustion and senescence being the dominant processes. Following treatment, the phenotypic and transcriptional profile of CD8+ T cells diverged between responders and nonresponders. Response to therapy correlated with upregulation of costimulatory, and downregulation of apoptotic and inhibitory, T cell signaling pathways, indicative of restoration of T cell function. In functional studies, AML blasts directly altered CD8+ T cell viability, expansion, co-signaling and senescence marker expression. This CD8+ T cell dysfunction was in part reversible upon PD-1 blockade or OX40 costimulation in vitro.

CONCLUSION

Our findings highlight the uniqueness of AML in sculpting CD8+ T cell responses and the plasticity of their signatures upon chemotherapy response, providing a compelling rationale for integration of novel immunotherapies to augment antileukemia immunity.

FUNDING

This work was supported by the Leukemia & Lymphoma Society grant no. 6449-13; NIH grants UM1-CA186691 and R01-HL110907-01; the American Society for Blood and Marrow Transplantation New Investigator Award/Gabrielle's Angel Foundation; the Vienna Fund for Innovative Cancer Research; and by fellowships from the Wenner-Gren Foundation and the Swedish Society for Medical Research.

Signatures of CD8+ T cell dysfunction in AML patients and their reversibility with response to chemotherapy

BACKGROUND

Our understanding of phenotypic and functional signatures of CD8+ T cell dysfunction in acute myeloid leukemia (AML) is limited. Deciphering these deranged T cell functional states and how they are impacted by induction chemotherapy is essential for incorporation of novel immune-based strategies to restore and maintain antileukemia immunity.

METHODS

We utilized high-dimensional immunophenotyping, gene expression, and functional studies to characterize peripheral blood and bone marrow CD8+ T cells in 72 AML patients at diagnosis and after induction chemotherapy.

RESULTS

Our data suggest that multiple aspects of deranged T cell function are operative in AML at diagnosis, with exhaustion and senescence being the dominant processes. Following treatment, the phenotypic and transcriptional profile of CD8+ T cells diverged between responders and nonresponders. Response to therapy correlated with upregulation of costimulatory, and downregulation of apoptotic and inhibitory, T cell signaling pathways, indicative of restoration of T cell function. In functional studies, AML blasts directly altered CD8+ T cell viability, expansion, co-signaling and senescence marker expression. This CD8+ T cell dysfunction was in part reversible upon PD-1 blockade or OX40 costimulation in vitro.

CONCLUSION

Our findings highlight the uniqueness of AML in sculpting CD8+ T cell responses and the plasticity of their signatures upon chemotherapy response, providing a compelling rationale for integration of novel immunotherapies to augment antileukemia immunity.

FUNDING

This work was supported by the Leukemia & Lymphoma Society grant no. 6449-13; NIH grants UM1-CA186691 and R01-HL110907-01; the American Society for Blood and Marrow Transplantation New Investigator Award/Gabrielle's Angel Foundation; the Vienna Fund for Innovative Cancer Research; and by fellowships from the Wenner-Gren Foundation and the Swedish Society for Medical Research.

Mass Cytometry for the Assessment of Immune Reconstitution After Hematopoietic Stem Cell Transplantation

Mass cytometry, or Cytometry by Time-Of-Flight, is a powerful new platform for high-dimensional single-cell analysis of the immune system. It enables the simultaneous measurement of over 40 markers on individual cells through the use of monoclonal antibodies conjugated to rare-earth heavy-metal isotopes. In contrast to the fluorochromes used in conventional flow cytometry, metal isotopes display minimal signal overlap when resolved by single-cell mass spectrometry. This review focuses on the potential of mass cytometry as a novel technology for studying immune reconstitution in allogeneic hematopoietic stem cell transplant (HSCT) recipients. Reconstitution of a healthy donor-derived immune system after HSCT involves the coordinated regeneration of innate and adaptive immune cell subsets in the recipient. Mass cytometry presents an opportunity to investigate immune reconstitution post-HSCT from a systems-level perspective, by allowing the phenotypic and functional features of multiple cell populations to be assessed simultaneously. This review explores the current knowledge of immune reconstitution in HSCT recipients and highlights recent mass cytometry studies contributing to the field.

Sex Differences in HIV Infection: Mystique Versus Machismo

Biological sex is a determinant of both susceptibility to and pathogenesis of multiple infections, including HIV. These differences have effects on the spectrum of HIV disease from acquisition to eradication, with diverse mechanisms including distinct chromosomal complements, variation in microbiota composition, hormonal effects on transcriptional profiles, and expression of different immunoregulatory elements. With a comparative biology approach, these sex differences can be used to highlight protective and detrimental immune activation pathways, to identify strategies for effective prevention, treatment, and curative interventions.

Chronic hepatitis C virus infection irreversibly impacts human natural killer cell repertoire diversity

Diversity is a central requirement for the immune system’s capacity to adequately clear a variety of different infections. As such, natural killer (NK) cells represent a highly diverse population of innate lymphocytes important in the early response against viruses. Yet, the extent to which a chronic pathogen affects NK cell diversity is largely unknown. Here we study NK cell functional diversification in chronic hepatitis C virus (HCV) infection. High-dimensional flow cytometer assays combined with stochastic neighbor embedding analysis reveal that chronic HCV infection induces functional imprinting on human NK cells that is largely irreversible and persists long after successful interventional clearance of the virus. Furthermore, HCV infection increases inter-individual, but decreases intra-individual, NK cell diversity. Taken together, our results provide insights into how the history of infections affects human NK cell diversity.

Natural killer (NK) cells are important immune cells for mediating antiviral immunity. Here the authors show that chronic hepatitis C virus infection in human can imprint lasting functional phenotypes in NK cells to increase their inter-individual but decrease intra-individual diversity.

Tracking KLRC2 (NKG2C)+ memory-like NK cells in SIV+ and rhCMV+ rhesus macaques

Natural killer (NK) cells classically typify the nonspecific effector arm of the innate immune system, but have recently been shown to possess memory-like properties against multiple viral infections, most notably CMV. Expression of the activating receptor NKG2C is elevated on human NK cells in response to infection with CMV as well as HIV, and may delineate cells with memory and memory-like functions. A better understanding of how NKG2C+ NK cells specifically respond to these pathogens could be significantly advanced using nonhuman primate (NHP) models but, to date, it has not been possible to distinguish NKG2C from its inhibitory counterpart, NKG2A, in NHP because of unfaithful antibody cross-reactivity. Using novel RNA-based flow cytometry, we identify for the first time true memory NKG2C+ NK cells in NHP by gene expression (KLRC2), and show that these cells have elevated frequencies and diversify their functional repertoire specifically in response to rhCMV and SIV infections.

Glycyrrhizin ameliorates atopic dermatitis-like symptoms through inhibition of HMGB1

Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease prevalent worldwide. This study investigated the effects of glycyrrhizin, an extract of licorice root, on the well-established model of 2,4-dinitrochlorobenzene-induced AD-like symptoms in mice. The severity of dermatitis, histopathological changes, serum IgE levels, changes in expression of high-mobility group box 1 (HMGB1), the receptor for advanced glycation end products (RAGE), nuclear factor (NF)-κB and inflammatory cytokines were evaluated. Treatment with glycyrrhizin inhibited the HMGB1 signaling cascade and ameliorated the symptoms of AD. Furthermore, in an in vitro study, the expression of RAGE was detected in a mouse mast cell line, P815 cells, and rmHMGB1 was found to be a potent inducer of mast cell activation by increasing Ca²⁺ influx, upregulating the CD117 and activating NF-κB signaling; these effects were also inhibited by glycyrrhizin. These findings implicate HMGB1 in the pathogenesis of AD and suggest that GL could be an effective therapeutic approach for cutaneous inflammation.

Diversification of human NK cells: Lessons from deep profiling

NK cells are innate lymphocytes with important roles in immunoregulation, immunosurveillance, and cytokine production. Originally defined on the functional basis of their "natural" ability to lyse tumor targets and thought to be a relatively homogeneous group of lymphocytes, NK cells possess a remarkable degree of phenotypic and functional diversity due to the combinatorial expression of an array of activating and inhibitory receptors. Diversification of NK cells is multifaceted: mechanisms of NK cell education that promote self-tolerance result in a heterogeneous repertoire that further diversifies upon encounters with viral pathogens. Here, we review the genetic, developmental, and environmental sources of NK cell diversity with a particular focus on deep profiling and single-cell technologies that will enable a more thorough and accurate dissection of this intricate and poorly understood lymphocyte lineage.

Cytokine-induced memory-like natural killer cells exhibit enhanced responses against myeloid leukemia

Natural killer (NK) cells are an emerging cellular immunotherapy for patients with acute myeloid leukemia (AML); however, the best approach to maximize NK cell antileukemia potential is unclear. Cytokine-induced memory-like NK cells differentiate after a brief preactivation with interleukin-12 (IL-12), IL-15, and IL-18 and exhibit enhanced responses to cytokine or activating receptor restimulation for weeks to months after preactivation. We hypothesized that memory-like NK cells exhibit enhanced antileukemia functionality. We demonstrated that human memory-like NK cells have enhanced interferon-γ production and cytotoxicity against leukemia cell lines or primary human AML blasts in vitro. Using mass cytometry, we found that memory-like NK cell functional responses were triggered against primary AML blasts, regardless of killer cell immunoglobulin-like receptor (KIR) to KIR-ligand interactions. In addition, multidimensional analyses identified distinct phenotypes of control and memory-like NK cells from the same individuals. Human memory-like NK cells xenografted into mice substantially reduced AML burden in vivo and improved overall survival. In the context of a first-in-human phase 1 clinical trial, adoptively transferred memory-like NK cells proliferated and expanded in AML patients and demonstrated robust responses against leukemia targets. Clinical responses were observed in five of nine evaluable patients, including four complete remissions. Thus, harnessing cytokine-induced memory-like NK cell responses represents a promising translational immunotherapy approach for patients with AML.

The Broad Spectrum of Human Natural Killer Cell Diversity

Natural killer (NK) cells provide protection against infectious pathogens and cancer. For decades it has been appreciated that two major NK cell subsets (CD56^bright and CD56^dim) exist in humans and have distinct anatomical localization patterns, phenotypes, and functions in immunity. In light of this traditional NK cell dichotomy, it is now clear that the spectrum of human NK cell diversity is much broader than originally appreciated as a result of variegated surface receptor, intracellular signaling molecule, and transcription factor expression; tissue-specific imprinting; and foreign antigen exposure. The recent discoveries of tissue-resident NK cell developmental intermediates, non-NK innate lymphoid cells, and the capacity for NK cells to adapt and differentiate into long-lived memory cells has added further complexity to this field. Here we review our current understanding of the breadth and generation of human NK cell diversity.

Redefining Memory: Building the Case for Adaptive NK Cells

Classically, natural killer (NK) cells have been defined by nonspecific innate killing of virus-infected and tumor cells. However, burgeoning evidence suggests that the functional repertoire of NK cells is far more diverse than has been previously appreciated, thus raising the possibility that there may be unexpected functional specialization and even adaptive capabilities among NK cell subpopulations. Some of the first evidence that NK cells respond in an antigen-specific fashion came from experiments revealing that subpopulations of murine NK cells were able to respond to a specific murine cytomegalovirus (MCMV) protein and that in the absence of T and B cells, murine NK cells also mediated adaptive immune responses to a secondary challenge with specific haptens. These data have been followed by demonstrations of NK cell memory of viruses and viral antigens in mice and primates. Herein, we discuss different forms of NK cell antigen specificity and how these responses may be tuned to specific viral pathogens, and we provide assessment of the current literature that may explain molecular mechanisms of the novel phenomenon of NK cell memory.

High-resolution phenotyping identifies NK cell subsets that distinguish healthy children from adults

Natural killer (NK) cells are critical in immune defense against infected, stressed or transformed cells. Their function is regulated by the heterogeneous expression of a wide array of surface receptors that shape its phenotypic diversity. Although NK cells develop in the bone marrow and secondary lymphoid tissues, substantive differentiation is apparent in the peripheral blood including known age-related variation. In order to gain greater insight into phenotypic and functional variation within peripheral blood NK cells across age groups, we used multi-parametric, polyfunctional flow cytometry to interrogate the NK cell variability in 20 healthy adults and 15 5–10, 11–15 and 16–20 year-old children. We found that the normative ranges in both adults and children displayed great inter-individual variation for most markers. While the expression of several receptors did not differ, among those that did, the majority of the differences existed between adults and the three pediatric groups, rather than among children of different ages. Interestingly, we also identified variation in the individual expression of some markers by sex and ethnicity. Combinatorial analysis of NK cell receptors revealed intermediate subsets between the CD56^bright and CD56^dim NK cells. Furthermore, on examining the NK cell diversity by age, adults were discovered to have the lowest developmental diversity. Thus, our findings identify previously unappreciated NK cell subsets potentially distinguishing children from adults and suggest functional correlates that may have relevance in age-specific host defense.

Regulatory myeloid cells: an underexplored continent in B-cell lymphomas

In lymphomas arising from the germinal center, prognostic factors are linked to the myeloid compartment. In particular, high circulating monocyte or myeloid-derived suppressor cell counts are associated with poor prognosis for patients with high-grade B-cell lymphomas. Macrophages with an M2 phenotype are enriched within lymphoma tumors. However, the M1/M2 nomenclature is now deprecated and the clinical impact of this phenotype remains controversial. Across cancer types, myeloid cells are primarily thought to function as immune suppressors during tumor initiation and maintenance, but the biological mechanisms behind the myeloid signatures are still poorly understood in germinal center B-cell lymphomas. Herein, we describe the role and clinical relevance of myeloid cells in B-cell lymphoma and propose innovative approaches to decipher this complex cellular compartment. Indeed, characterization of this heterogeneous cell ecosystem has been largely accomplished with "low-resolution" approaches like morphological evaluation and immunohistochemistry, where cells are characterized using a few proteins and qualitative metrics. High-resolution, quantitative approaches, such as mass cytometry, are valuable to better understand myeloid cell diversity, functions, and to identify potential targets for novel therapies.

Mass cytometry deep phenotyping of human mononuclear phagocytes and myeloid-derived suppressor cells from human blood and bone marrow

The monocyte phagocyte system (MPS) includes numerous monocyte, macrophage, and dendritic cell (DC) populations that are heterogeneous, both phenotypically and functionally. In this study, we sought to characterize those diverse MPS phenotypes with mass cytometry (CyTOF). To identify a deep phenotype of monocytes, macrophages, and DCs, a panel was designed to measure 38 identity, activation, and polarization markers, including CD14, CD16, HLA-DR, CD163, CD206, CD33, CD36, CD32, CD64, CD13, CD11b, CD11c, CD86, and CD274. MPS diversity was characterized for 1) circulating monocytes from healthy donors, 2) monocyte-derived macrophages further polarized in vitro (i.e., M-CSF, GM-CSF, IL-4, IL-10, IFN-γ, or LPS long-term stimulations), 3) monocyte-derived DCs, and 4) myeloid-derived suppressor cells (MDSCs), generated in vitro from bone marrow and/or peripheral blood. Known monocyte subsets were detected in peripheral blood to validate the panel and analysis pipeline. Then, using various culture conditions and stimuli before CyTOF analysis, we constructed a multidimensional framework for the MPS compartment, which was registered against historical M1 or M2 macrophages, monocyte subsets, and DCs. Notably, MDSCs generated in vitro from bone marrow expressed more S100A9 than when generated from peripheral blood. Finally, to test the approach in vivo, peripheral blood from patients with melanoma (n = 5) was characterized and observed to be enriched for MDSCs with a phenotype of CD14+HLA-DRlowS100A9high (3% of PBMCs in healthy donors, 15.5% in patients with melanoma, P < 0.02). In summary, mass cytometry comprehensively characterized phenotypes of human monocyte, MDSC, macrophage, and DC subpopulations in both in vitro models and patients.

Immune Checkpoint Function of CD85j in CD8 T Cell Differentiation and Aging

Aging is associated with an increased susceptibility to infection and a failure to control latent viruses thought to be driven, at least in part, by alterations in CD8 T cell function. The aging T cell repertoire is characterized by an accumulation of effector CD8 T cells, many of which express the negative regulatory receptor CD85j. To define the biological significance of CD85j expression on CD8 T cells and to address the question whether presence of CD85j in older individuals is beneficial or detrimental for immune function, we examined the specific attributes of CD8 T cells expressing CD85j as well as the functional role of CD85j in antigen-specific CD8 T cell responses during immune aging. Here, we show that CD85j is mainly expressed by terminally differentiated effector (TEMRAs) CD8 T cells, which increase with age, in cytomegalovirus (CMV) infection and in males. CD85j⁺ CMV-specific cells demonstrate clonal expansion. However, TCR diversity is similar between CD85j⁺ and CD85j⁻ compartments, suggesting that CD85j does not directly impact the repertoire of antigen-specific cells. Further phenotypic and functional analyses revealed that CD85j identifies a specific subset of CMV-responsive CD8 T cells that coexpress a marker of senescence (CD57) but retain polyfunctional cytokine production and expression of cytotoxic mediators. Blocking CD85j binding enhanced proliferation of CMV-specific CD8 T cells upon antigen stimulation but did not alter polyfunctional cytokine production. Taken together, these data demonstrate that CD85j characterizes a population of “senescent,” but not exhausted antigen-specific effector CD8 T cells and indicates that CD85j is an important checkpoint regulator controlling expansion of virus-specific T cells during aging. Inhibition of CD85j activity may be a mechanism to promote stronger CD8 T cell effector responses during immune aging.

DKK3 attenuates the cytotoxic effect of natural killer cells on CD133+ gastric cancer cells

Cancer stem cell (CSCs) has started a new era in cancer research. CD133 is a widely used marker for identification of CSCs. More and more studies showed that NK cells preferentially target cancer stem-like cells. However, the deeper mechanism of the susceptibility of cancer stem cells to NK cells remains unclear. In this study, we isolated CD133 positive population of a gastric cancer cell line, BGC823 cells, and cultured with NK cells. We found that CD133 could efficiently active NK cells in an NKG2D-dependent manner. DKK3 has been demonstrated as a suppressor in many cancers. Interestingly, we found that DKK3 suppressed CD133-induced activation in NK cells by inhibiting Erk pathway and immunological synapse (IS) formation. NK cells-based CSCs immunotherapy may be a novel approach for cancer therapy.

The natural killer cell response to West Nile virus in young and old individuals with or without a prior history of infection

West Nile virus (WNV) typically leads to asymptomatic infection but can cause severe neuroinvasive disease or death, particularly in the elderly. Innate NK cells play a critical role in antiviral defenses, yet their role in human WNV infection is poorly defined. Here we demonstrate that NK cells mount a robust, polyfunctional response to WNV characterized by cytolytic activity, cytokine and chemokine secretion. This is associated with downregulation of activating NK cell receptors and upregulation of NK cell activating ligands for NKG2D. The NK cell response did not differ between young and old WNV-naïve subjects, but a history of symptomatic infection is associated with more IFN-γ producing NK cell subsets and a significant decline in a specific NK cell subset. This NK repertoire skewing could either contribute to or follow heightened immune pathogenesis from WNV infection, and suggests that NK cells could play an important role in WNV infection in humans.

Deciphering the killer-cell immunoglobulin-like receptor system at super-resolution for natural killer and T-cell biology

Killer-cell immunoglobulin-like receptors (KIRs) are components of two fundamental biological systems essential for human health and survival. First, they contribute to host immune responses, both innate and adaptive, through their expression by natural killer cells and T cells. Second, KIR play a key role in regulating placentation, and hence reproductive success. Analogous to the diversity of their human leucocyte antigen class I ligands, KIR are extremely polymorphic. In this review, we describe recent developments, fuelled by methodological advances, that are helping to decipher the KIR system in terms of haplotypes, polymorphisms, expression patterns and their ligand interactions. These developments are delivering deeper insight into the relevance of KIR in immune system function, evolution and disease.

The newborn human NK cell repertoire is phenotypically formed but functionally reduced

BACKGROUND

Infection is a leading cause of death worldwide in babies under 1 month of age. Better vaccines and therapeutics are desperately needed for this vulnerable population.

METHODS

Because newborns rely heavily on the innate immune system, we evaluated cell phenotype and function of some of the earliest cellular responders during infection, natural killer (NK) cells. We used mass cytometry to provide a comprehensive comparison of NK cells from umbilical cord blood and adult peripheral blood.

RESULTS

In unsupervised analyses, including viSNE and principal component analysis, the structure of the cord blood and adult NK cell repertoires are highly similar, distinguishable mainly by maturity-related markers expressed on rare subpopulations of cells. However, in functional analyses, cord blood NK cells show reduced degranulation and cytokine production following target recognition, as well as antibody-dependent cell-mediated cytotoxicity and apoptosis induction in targets.

CONCLUSIONS

These findings show that the structure of the NK cell repertoire is intact at birth, suggesting great potential for vaccine and therapeutic strategies targeting this cell population. © 2016 International Clinical Cytometry Society.

Convergence of Innate and Adaptive Immunity during Human Aging

Aging is associated with profound changes in the human immune system, a phenomenon referred to as immunosenescence. This complex immune remodeling affects the adaptive immune system and the CD8⁺ T cell compartment in particular, leading to the accumulation of terminally differentiated T cells, which can rapidly exert their effector functions at the expenses of a limited proliferative potential. In this review, we will discuss evidence suggesting that senescent αβCD8⁺ T cells acquire the hallmarks of innate-like T cells and use recently acquired NK cell receptors as an alternative mechanism to mediate rapid effector functions. These cells concomitantly lose expression of co-stimulatory receptors and exhibit decreased T cell receptor signaling, suggesting a functional shift away from antigen-specific activation. The convergence of innate and adaptive features in senescent T cells challenges the classic division between innate and adaptive immune systems. Innate-like T cells are particularly important for stress and tumor surveillance, and we propose a new role for these cells in aging, where the acquisition of innate-like functions may represent a beneficial adaptation to an increased burden of malignancy with age, although it may also pose a higher risk of autoimmune disorders.

Natural Killer Cell Diversity in Viral Infection: Why and How Much?

Natural killer cells are a diverse group of innate lymphocytes that are specialized to rapidly respond to cancerous or virus-infected cells. NK cell function is controlled by the integration of signals from activating and inhibitory receptors expressed at the cell surface. Variegated expression patterns of these activating and inhibitory receptors at the single cell level leads to a highly diverse NK cell repertoire. Here I review the factors that influence NK cell repertoire diversity and its functional consequences for our ability to fight viruses.

T Cells Going Innate

Natural killer (NK) cell receptors (NKRs) play a crucial role in the homeostasis of antigen-experienced T cells. Indeed, prolonged antigen stimulation may induce changes in the receptor repertoire of T cells to a profile that features NKRs. Chronic antigen exposure, at the same time, has been shown to trigger the loss of costimulatory CD28 molecules with recently reported intensified antigen thresholds of antigen-experienced CD8(+) T cells. In transplantation, NKRs have been shown to assist allograft rejection in a CD28-independent fashion. We discuss here a role for CD28-negative T cells that have acquired the competency of the NKR machinery, potentially promoting allorecognition either through T cell receptor (TCR) crossreactivity or independently from TCR recognition. Collectively, NKRs can bring about innate-like T cells by providing alternative costimulatory pathways that gain relevance in chronic inflammation, potentially leading to resistance to CD28-targeting immunosuppressants.

Human NK cell repertoire diversity reflects immune experience and correlates with viral susceptibility

Innate natural killer (NK) cells are diverse at the single-cell level because of variegated expressions of activating and inhibitory receptors, yet the developmental roots and functional consequences of this diversity remain unknown. Because NK cells are critical for antiviral and antitumor responses, a better understanding of their diversity could lead to an improved ability to harness them therapeutically. We found that NK diversity is lower at birth than in adults. During an antiviral response to either HIV-1 or West Nile virus, NK diversity increases, resulting in terminal differentiation and cytokine production at the cost of cell division and degranulation. In African women matched for HIV-1 exposure risk, high NK diversity is associated with increased risk of HIV-1 acquisition. Existing diversity may therefore decrease the flexibility of the antiviral response. Collectively, the data reveal that human NK diversity is a previously undefined metric of immune history and function that may be clinically useful in forecasting the outcomes of infection and malignancy.

CD57 in human natural killer cells and T-lymphocytes

The CD57 antigen (alternatively HNK-1, LEU-7, or L2) is routinely used to identify terminally differentiated 'senescent' cells with reduced proliferative capacity and altered functional properties. In this article, we review current understanding of the attributes of CD57-expressing T-cells and NK cells in both health and disease and discuss how this marker can inform researchers about their likely functions in human blood and tissues in vivo. While CD57 expression on human lymphocytes indicates an inability to proliferate, these cells also display high cytotoxic potential, and CD57(pos) NK cells exhibit both memory-like features and potent effector functions. Accordingly, frequencies of CD57-expressing cells in blood and tissues have been correlated with clinical prognosis in chronic infections or various cancers and with human aging. Functional modulation of senescent CD57(pos) T-cells and mature CD57(pos) NK cells may therefore represent innovative strategies for protection against human immunological aging and/or various chronic diseases.

Influence of In Vitro IL-2 or IL-15 Alone or in Combination with Hsp 70 Derived 14-Mer Peptide (TKD) on the Expression of NK Cell Activatory and Inhibitory Receptors on Peripheral Blood T Cells, B Cells and NKT Cells

Previous studies from Multhoff and colleagues reported that plasma membrane Hsp70 acts as a tumour-specific recognition structure for activated NK cells, and that the incubation of NK cells with Hsp70 and/or a 14-mer peptide derived from the N-terminal sequence of Hsp70 (TKDNNLLGRFELSG, TKD, aa 450–463) plus a low dose of IL-2 triggers NK cell proliferation and migration, and their capacity to kill cancer cells expressing membrane Hsp70. Herein, we have used flow cytometry to determine the influence of in vitro stimulation of peripheral blood mononuclear cells from healthy individuals with IL-2 or IL-15, either alone or in combination with TKD peptide on the cell surface expression of CD94, NK cell activatory receptors (CD16, NK2D, NKG2C, NKp30, NKp44, NKp46, NKp80, KIR2DL4, DNAM-1 and LAMP1) and NK cell inhibitory receptors (NKG2A, KIR2DL2/L3, LIR1/ILT-2 and NKR-P1A) by CD3+CD56+ (NKT), CD3+CD4+, CD3+CD8+ and CD19+ populations. NKG2D, DNAM-1, LAMP1 and NKR-P1A expression was upregulated after the stimulation with IL-2 or IL-15 alone or in combination with TKD in NKT, CD8+ T cells and B cells. CD94 was upregulated in NKT and CD8+ T cells. Concurrently, an increase in a number of CD8+ T cells expressing LIR1/ILT-2 and CD4+ T cells positive for NKR-P1A was observed. The proportion of CD8+ T cells that expressed NKG2D was higher after IL-2/TKD treatment, when compared with IL-2 treatment alone. In comparison with IL-15 alone, IL-15/TKD treatment increased the proportion of NKT cells that were positive for CD94, LAMP1 and NKRP-1A. The more potent effect of IL-15/TKD on cell surface expression of NKG2D, LIR1/ILT-2 and NKRP-1A was observed in B cells compared with IL-15 alone. However, this increase was not of statistical significance. IL-2/TKD induced significant upregulation of LAMP1 in CD8+ T cells compared with IL-2 alone. Besides NK cells, other immunocompetent cells present within the fraction of peripheral blood mononuclear cells were influenced by the treatment with low-dose interleukins themselves or in combination with hsp70 derived (TKD) peptide.

Human NK Cell Diversity in Viral Infection: Ramifications of Ramification

Natural killer (NK) cells are a unique lymphocyte lineage with remarkable agility in the rapid destruction of virus-infected cells. They are also the most poorly understood class of lymphocyte. A spectrum of activating and inhibitory receptors at the NK cell surface leads to an unusual and difficult-to-study mechanism of cellular recognition, as well as a very high capacity for diversity at the single-cell level. Here, we review the evidence for the role of NK cells in the earliest stage of human viral infection, and in its prevention. We argue that single-cell diversity is a logical evolutionary adaptation for their position in the immune response and contributes to their ability to kill virus-infected cells. Finally, we look to the future, where emerging single-cell technologies will enable a new generation of rigorous and clinically relevant studies on NK cells accounting for all of their unique and diverse characteristics.