Antitumor Responses of Invariant Natural Killer T Cells

Lymphocyte profile in peripheral blood of patients with multiple myeloma

Multiple myeloma (MM) is a disease which remains incurable. One of the main reasons is a weakened immune system that allows MM cells to survive. Therefore, the current research is focused on the study of immune system imbalance in MM to find the most effective immunotherapy strategies. Aiming to identify the key points of immune failure in MM patients, we analysed peripheral lymphocytes subsets from MM patients (n = 57) at various stages of the disease course and healthy individuals (HI, n = 15) focusing on T, NK, iNKT, B cells and NK-cell cytokines. Our analysis revealed that MM patients exhibited immune alterations in all studied immune subsets. Compared to HI, MM patients had a significantly lower proportion of CD4 + T cells (19.55% vs. 40.85%; p < 0.001) and CD4 + iNKT cells (18.8% vs. 40%; p < 0.001), within B cells an increased proportion of CD21LCD38L subset (4.5% vs. 0.4%; p < 0.01) and decreased level of memory cells (unswitched 6.1% vs. 14.7%; p < 0.001 and switched 7.8% vs. 11.2%; NS), NK cells displaying signs of activation and exhaustion characterised by a more than 2-fold increase in SLAMF7 MFI (p < 0.001), decreased expression of NKG2D (MFI) and NKp46 (%) on CD16 + 56 + and CD16 + 56- subset respectively (p < 0.05), Effective immunotherapy needs to consider these immune defects and monitoring of the immune status of MM patients is essential to define better interventions in the future.

Proteomic profiling and biomarker discovery for predicting the response to PD-1 inhibitor immunotherapy in gastric cancer patients

Background: Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment; however, a significant proportion of gastric cancer (GC) patients do not respond to this therapy. Consequently, there is an urgent need to elucidate the mechanisms underlying resistance to ICIs and identify robust biomarkers capable of predicting the response to ICIs at treatment initiation. Methods: In this study, we collected GC tissues from 28 patients prior to the administration of anti-programmed death 1 (PD-1) immunotherapy and conducted protein quantification using high-resolution mass spectrometry (MS). Subsequently, we analyzed differences in protein expression, pathways, and the tumor microenvironment (TME) between responders and non-responders. Furthermore, we explored the potential of these differences as predictive indicators. Finally, using machine learning algorithms, we screened for biomarkers and constructed a predictive model. Results: Our proteomics-based analysis revealed that low activity in the complement and coagulation cascades pathway (CCCP) and a high abundance of activated CD8 T cells are positive signals corresponding to ICIs. By using machine learning, we successfully identified a set of 10 protein biomarkers, and the constructed model demonstrated excellent performance in predicting the response in an independent validation set (N = 14; area under the curve [AUC] = 0.959). Conclusion: In summary, our proteomic analyses unveiled unique potential biomarkers for predicting the response to PD-1 inhibitor immunotherapy in GC patients, which may provide the impetus for precision immunotherapy.

CTLs heterogeneity and plasticity: implications for cancer immunotherapy

Cytotoxic T lymphocytes (CTLs) play critical antitumor roles, encompassing diverse subsets including CD4+, NK, and γδ T cells beyond conventional CD8+ CTLs. However, definitive CTLs biomarkers remain elusive, as cytotoxicity-molecule expression does not necessarily confer cytotoxic capacity. CTLs differentiation involves transcriptional regulation by factors such as T-bet and Blimp-1, although epigenetic regulation of CTLs is less clear. CTLs promote tumor killing through cytotoxic granules and death receptor pathways, but may also stimulate tumorigenesis in some contexts. Given that CTLs cytotoxicity varies across tumors, enhancing this function is critical. This review summarizes current knowledge on CTLs subsets, biomarkers, differentiation mechanisms, cancer-related functions, and strategies for improving cytotoxicity. Key outstanding questions include refining the CTLs definition, characterizing subtype diversity, elucidating differentiation and senescence pathways, delineating CTL-microbe relationships, and enabling multi-omics profiling. A more comprehensive understanding of CTLs biology will facilitate optimization of their immunotherapy applications. Overall, this review synthesizes the heterogeneity, regulation, functional roles, and enhancement strategies of CTLs in antitumor immunity, highlighting gaps in our knowledge of subtype diversity, definitive biomarkers, epigenetic control, microbial interactions, and multi-omics characterization. Addressing these questions will refine our understanding of CTLs immunology to better leverage cytotoxic functions against cancer.

Melanoma Cells Inhibit iNKT Cell Functions via PGE2 and IDO1

Invariant natural killer T (iNKT) cells are a distinct group of immune cells known for their immunoregulatory and cytotoxic activities, which are crucial in immune surveillance against tumors. They have been extensively investigated as a potential target for adoptive cell immunotherapy. Despite the initial promise of iNKT cell-based immunotherapy as a treatment for melanoma patients, its effective utilization has unfortunately yielded inconsistent outcomes. The primary cause of this failure is the immunosuppressive tumor microenvironment (TME). In this study, we specifically directed our attention towards melanoma cells, as their roles within the TME remain partially understood and require further elucidation. Methods: We conducted co-culture experiments involving melanoma cell lines and iNKT cells. Results: We demonstrated that melanoma cell lines had a significant impact on the proliferation and functions of iNKT cells. Our findings revealed that co-culture with melanoma cell lines led to a significant impairment in the expression of the NKG2D receptor and cytolytic granules in iNKT cells. Moreover, we observed a strong impairment of their cytotoxic capability induced by the presence of melanoma cells. Furthermore, through the use of selective inhibitors targeting IDO1 and COX-2, we successfully demonstrated that the melanoma cell line's ability to impair iNKT cell activation and functions was attributed to the up-regulation of IDO1 expression and PGE2 production.

Safety and Clinical Response to Combined Immunotherapy with Autologous iNKT Cells and PD-1+CD8+ T Cells in Patients Failing First-line Chemotherapy in Stage IV Pancreatic Cancer

Purpose

A phase I clinical trial was conducted to assess the safety and feasibility of invariant natural killer T (iNKT) cells combined with PD-1⁺CD8⁺ T cells in patients with advanced pancreatic cancer and failing the first-line chemotherapy.

Patients and Methods

Fifteen eligible patients were enrolled, of whom 9 received at least three cycles of treatment each. In total, 59 courses were administered.

Results

Fever was the most common adverse event, peaking at about 2-4 hours after cell infusion and reverting within 24 hours without treatment in all patients. Influenza-like reactions such as headache, myalgia, and arthralgia were also observed in 4, 4, and 3 of the patients, respectively. In addition, vomiting and dizziness were prevalent, while abdominal pain, chest pain, rash, and stuffy nose were rare adverse events, each reported in 1 patient. Side effects above grade 2 were not observed. Two patients achieved partial regression, while 1 patient experienced disease progression assessed 4 weeks after the third course. Three patients are still alive at the time of writing and have progression-free survival longer than 12 months. The overall survival time has been extended to over 12 months in 6 of the 9 patients. No constant changes of CD4⁺ T, B, and NK cells were recorded except for elevated CD8⁺ T cells after the first course.

Conclusions

The combination of autologous iNKT cells and PD-1⁺CD8⁺ T cells was a safe therapeutic strategy against advanced pancreatic cancer. The patients exhibited a potentially promising prolonged survival time. Further study appears warranted to evaluate the efficacy of these combined cell infusions in pancreatic cancer.

Trial registration

This trial was included in the clinical trial which was registered in ClinicalTrials.gov (ID:NCT03093688) on March 15, 2017.

Significance

There is an unmet need for novel, more effective, and tolerable therapies for pancreatic cancer. Here we present a phase I clinical trial employing iNKT cells combined with PD-1⁺CD8⁺ T cells in 9 patients with advanced pancreatic cancer and failing the first-line chemotherapy. The combined immunotherapy was shown to be feasible in the enrolled patients with limited side effects and optimistic clinical responses, which could bring opportunity of therapeutic advancement.

Role of NKT cells in cancer immunotherapy-from bench to bed

Natural killer T (NKT) cells are a specific T cell subset known to express the αβ-T cell receptor (TCR) for antigens identification and express typical NK cell specifications, such as surface expression of CD56 and CD16 markers as well as production of granzyme. Human NKT cells are divided into two subgroups based on their cytokine receptor and TCR repertoire. Both of them are CD1-restricted and recognize lipid antigens presented by CD1d molecules. Studies have demonstrated that these cells are essential in defense against malignancies. These cells secret proinflammatory and regulatory cytokines that stimulate or suppress immune system responses. In several murine tumor models, activation of type I NKT cells induces tumor rejection and inhibits metastasis's spread. However, type II NKT cells are associated with an inhibitory and regulatory function during tumor immune responses. Variant NKT cells may suppress tumor immunity via different mechanisms that require cross-talk with other immune-regulatory cells. NKT-like cells display high tumor-killing abilities against many tumor cells. In the recent decade, different studies have been performed based on the application of NKT-based immunotherapy for cancer therapy. Moreover, manipulation of NKT cells through administering autologous dendritic cell (DC) loaded with α-galactosylceramide (α-GalCer) and direct α-GalCer injection has also been tested. In this review, we described different subtypes of NKT cells, their function in the anti-tumor immune responses, and the application of NKT cells in cancer immunotherapy from bench to bed.

Phase II study of α-galactosylceramide-pulsed antigen-presenting cells in patients with advanced or recurrent non-small cell lung cancer

Background

Invariant natural killer T (iNKT) cells produce copious amounts of cytokines in response to specific glycolipid antigens such as α-galactosylceramide (αGalCer) presented by CD1d-expressing antigen-presenting cells (APCs), thus orchestrating other immune cells to fight tumors. Because of their ability to induce strong antitumor responses activated by αGalCer, iNKT cells have been studied for their application in cancer immunotherapy. In our previous phase I/II trial in non-small cell lung cancer (NSCLC) patients who had completed the standard treatment, we showed a relatively long median survival time without severe treatment-related adverse events. Based on these results, we performed a phase II trial to evaluate clinical responses, safety profiles and immune responses as a second-line treatment for advanced NSCLC.

Methods

Patients with advanced or recurrent NSCLC refractory to first-line chemotherapy were eligible. αGalCer-pulsed APCs were intravenously administered four times. Overall survival time was evaluated as the primary endpoint. The safety profile and immune responses after APC injection were also monitored. This study was an open label, single-arm, phase II clinical trial performed at Chiba University Hospital, Japan.

Results

Thirty-five patients were enrolled in this study, of which 32 (91.4%) completed the trial. No severe adverse events related to the treatment were observed. The estimated median survival time of the 35 cases was 21.9 months (95% CI, 14.8 to 26.0). One case (2.9%) showed a partial response, 14 cases (40.0%) remained as stable disease, and 19 cases (54.3%) were evaluated as progressive disease. The geometric mean number of iNKT cells in all cases was significantly decreased and the mean numbers of natural killer (NK) cells, interferon-γ-producing cells in response to αGalCer, and effector CD8+ T cells were significantly increased after the administration of αGalCer-pulsed APCs.

Conclusions

The intravenous administration of αGalCer-pulsed APCs was well-tolerated and was accompanied by prolonged overall survival. These results are encouraging and warrant further evaluation in a randomized phase III trial to demonstrate the survival benefit of this immunotherapy.

Trial registration number

UMIN000007321.

Distinct Bioenergetic Features of Human Invariant Natural Killer T Cells Enable Retained Functions in Nutrient-Deprived States

Invariant natural killer T (iNKT) cells comprise a unique subset of lymphocytes that are primed for activation and possess innate NK-like functional features. Currently, iNKT cell-based immunotherapies remain in early clinical stages, and little is known about the ability of these cells to survive and retain effector functions within the solid tumor microenvironment (TME) long-term. In conventional T cells (TCONV), cellular metabolism is linked to effector functions and their ability to adapt to the nutrient-poor TME. In contrast, the bioenergetic requirements of iNKT cells - particularly those of human iNKT cells - at baseline and upon stimulation are not well understood; neither is how these requirements affect effector functions such as production of cytokines and cytolytic proteins. We find that unlike TCONV, human iNKT cells are not dependent upon glucose or glutamine for these effector functions upon stimulation with anti-CD3 and anti-CD28. Additionally, transcriptional profiling revealed that stimulated human iNKT cells are less glycolytic than TCONV and display higher expression of fatty acid oxidation (FAO) and adenosine monophosphate-activated protein kinase (AMPK) pathway genes. Furthermore, stimulated iNKT cells displayed higher mitochondrial mass and membrane potential relative to TCONV. Real-time Seahorse metabolic flux analysis revealed that stimulated human iNKT cells utilize fatty acids as substrates for oxidation more than stimulated TCONV. Together, our data suggest that human iNKT cells possess different bioenergetic requirements from TCONV and display a more oxidative metabolic program relative to effector TCONV. Importantly, iNKT cell-based immunotherapeutic strategies could co-opt such unique features of iNKT cells to improve their efficacy and longevity of anti-tumor responses.

Lentiviral Vectors for T Cell Engineering: Clinical Applications, Bioprocessing and Future Perspectives

Lentiviral vectors have played a critical role in the emergence of gene-modified cell therapies, specifically T cell therapies. Tisagenlecleucel (Kymriah), axicabtagene ciloleucel (Yescarta) and most recently brexucabtagene autoleucel (Tecartus) are examples of T cell therapies which are now commercially available for distribution after successfully obtaining EMA and FDA approval for the treatment of blood cancers. All three therapies rely on retroviral vectors to transduce the therapeutic chimeric antigen receptor (CAR) into T lymphocytes. Although these innovations represent promising new therapeutic avenues, major obstacles remain in making them readily available tools for medical care. This article reviews the biological principles as well as the bioprocessing of lentiviral (LV) vectors and adoptive T cell therapy. Clinical and engineering successes, shortcomings and future opportunities are also discussed. The development of Good Manufacturing Practice (GMP)-compliant instruments, technologies and protocols will play an essential role in the development of LV-engineered T cell therapies.

Translating Unconventional T Cells and Their Roles in Leukemia Antitumor Immunity

Recently, cell-mediated immune response in malignant neoplasms has become the focus in immunotherapy against cancer. However, in leukemia, most studies on the cytotoxic potential of T cells have concentrated only on T cells that recognize peptide antigens (Ag) presented by polymorphic molecules of the major histocompatibility complex (MHC). This ignores the great potential of unconventional T cell populations, which include gamma-delta T cells (γδ), natural killer T cells (NKT), and mucosal-associated invariant T cells (MAIT). Collectively, these T cell populations can recognize lipid antigens, specially modified peptides and small molecule metabolites, in addition to having several other advantages, which can provide more effective applications in cancer immunotherapy. In recent years, these cell populations have been associated with a repertoire of anti- or protumor responses and play important roles in the dynamics of solid tumors and hematological malignancies, thus, encouraging the development of new investigations in the area. This review focuses on the current knowledge regarding the role of unconventional T cell populations in the antitumor immune response in leukemia and discusses why further studies on the immunotherapeutic potential of these cells are needed.

Expansion of Human iNKT Cells Ex Vivo

Invariant natural killer T (iNKT) cells are credited with antitumor activity by preclinical studies and clinical trials. Efficient expansion of iNKT cells ex vivo is essential for their translational usage. The culturing procedure described here provides an optimized method for ex vivo expansion of iNKT cells using recombinant human IL-15 (rhIL-15) and recombinant human IL-12 (rhIL-12), which results in cell products with enhanced cytokine secretion and cytotoxicity while maintaining the purity and viability of iNKT cells.

Fatty change of the liver microenvironment influences the metastatic potential of colorectal cancer

Fatty liver is the most common cause of liver disease, and its prevalence has been increasing globally. Colorectal cancer (CRC) accounts for approximately 10% of all cancers and metastasizes most commonly to the liver. Paget's ‘Seed and Soil’ theory of metastasis proposed that the secondary growth of cancer cells is dependent on the distal organ microenvironment. This implies that the risk of metastasis may change due to changes in the microenvironment of target organs. However, the association between steatosis, fatty change in the liver microenvironment, and liver metastasis has not been clarified. Here, we induced fatty liver conditions in BALB/c mice using a choline‐deficient high‐fat diet with 0.1% methionine (CDAHFD) and then injected the CT26 cells to produce experimental metastasis. The number of metastatic tumours was significantly increased in mice with severe fatty liver as compared to control mice. The average size of metastatic tumours was smaller in mice with moderate fatty liver than in control mice. The stromal components, including cancer‐associated fibroblasts, tumour‐associated macrophages and tumour‐infiltrating lymphocytes, were also examined. Metastatic tumours in fatty liver showed invasive growth patterns without a fibrotic capsule. Compared to control groups, the polarization of macrophages and subtypes of tumour‐infiltrating lymphocytes differed depending on the extent of fatty liver progression. These results indicated that fatty changes in the liver influenced liver metastasis of CRC. Although moderate fatty changes suppress the growth of metastatic tumours in the liver, a severe fatty microenvironment may promote invasion and metastasis through alteration of the tumour microenvironment (TME).

Functional significance of lymphocytes in pregnancy and lymphocyte immunotherapy in infertility: A comprehensive review and update

During pregnancy, the fetal-maternal interface underlies several dynamic alterations to permit the fetus to be cultivated and developed in the uterus, in spite of being identifies by the maternal immune system. A large variety of decidual leukocyte populations, including natural killer cells, NKT cells, innate lymphoid cells, dendritic cells, B cells, T cells, subpopulations of helper T cells play a vital role in controlling the trophoblast invasion, angiogenesis as well as vascular remodeling. In contrast, several regulatory immunosuppressive mechanisms, including regulatory T cells, regulatory B cells, several cytokines and mediators are involved in maintain the homeostasis of immune system in the fetal-maternal interface. Nonetheless, aberrant alterations in the balance of immune inflammatory or immunosuppressive arms have been associated with various pregnancy losses and infertilities. As a result, numerous strategies have been developed to revers dysregulated balance of immune players to increase the chance of successful pregnancy. Lymphocyte immunotherapy has been developed through utilization of peripheral white blood cells of the husband or others and administered into the mother to confer an immune tolerance for embryo's antigens. However, the results have not always been promising, implying to further investigations to improve the approach. This review attempts to clarify the involvement of lymphocytes in contributing to the pregnancy outcome and the potential of lymphocyte immunotherapy in treatment of infertilities with dysregulated immune system basis.

License to Kill: When iNKT Cells Are Granted the Use of Lethal Cytotoxicity

Invariant Natural Killer T (iNKT) cells are a non-conventional, innate-like, T cell population that recognize lipid antigens presented by the cluster of differentiation (CD)1d molecule. Although iNKT cells are mostly known for mediating several immune responses due to their massive and diverse cytokine release, these cells also work as effectors in various contexts thanks to their cytotoxic potential. In this Review, we focused on iNKT cell cytotoxicity; we provide an overview of iNKT cell subsets, their activation cues, the mechanisms of iNKT cell cytotoxicity, the specific roles and outcomes of this activity in various contexts, and how iNKT killing functions are currently activated in cancer immunotherapies. Finally, we discuss the future perspectives for the better understanding and potential uses of iNKT cell killing functions in tumor immunosurveillance.

Tumor Microenvironment

Background and Objectives: The tumor microenvironment has been widely implicated in tumorigenesis because it harbors tumor cells that interact with surrounding cells through the circulatory and lymphatic systems to influence the development and progression of cancer. In addition, nonmalignant cells in the tumor microenvironment play critical roles in all the stages of carcinogenesis by stimulating and facilitating uncontrolled cell proliferation. Aim: This study aims to explore the concept of the tumor microenvironment by conducting a critical review of previous studies on the topic. Materials and Methods: This review relies on evidence presented in previous studies related to the topic. The articles included in this review were obtained from different medical and health databases. Results and Discussion: The tumor microenvironment has received significant attention in the cancer literature, with a particular focus on its role in tumor development and progression. Previous studies have identified various components of the tumor microenvironment that influence malignant behavior and progression. In addition to malignant cells, adipocytes, fibroblasts, tumor vasculature, lymphocytes, dendritic cells, and cancer-associated fibroblasts are present in the tumor microenvironment. Each of these cell types has unique immunological capabilities that determine whether the tumor will survive and affect neighboring cells. Conclusion: The tumor microenvironment harbors cancer stem cells and other molecules that contribute to tumor development and progression. Consequently, targeting and manipulating the cells and factors in the tumor microenvironment during cancer treatment can help control malignancies and achieve positive health outcomes.

NK-mediated antibody-dependent cell-mediated cytotoxicity in solid tumors: biological evidence and clinical perspectives

The process of antibody-dependent cell-mediated cytotoxicity (ADCC) makes use of the innate immune cells providing antitumor cytotoxicity activated by antibodies linked to target cells. Natural killer (NK) cells are a small set of lymphocytes, but are considered the most important cells among those able to induce ADCC. They provoke innate immune responses and harmonise spontaneous cytotoxicity towards tumor and virus-infected cells. They are able to swiftly produce biochemical signals and cytokines so as to stimulate subsequent adaptive immune responses. Immunotherapeutics that target NK cells, augmenting their immune response, can cause the antitumor dynamics of the antibodies to be improved. The recent developments in the field of NK cell immunotherapy and genotypic factors which might affect patient responses to antibody-dependent immunotherapies are the main subject of this review, with a particular focus on the manipulations and strategies used to augment ADCC. In the next years combined treatment with monoclonal antibodies (mAbs) and immunomodulatory drugs will be an important part in antitumor therapy. The main challenge remains the difficulty in distinguishing in the clinical setting, between the target effect that many mAbs exert against specific cell membrane receptors and the ADCC effect that they too also can induce. Drugs able to activate NK cells, that are major actors in mAb-mediated ADCC, will improve the ADCC effect against tumors.

Soluble factors derived from neuroblastoma cell lines suppress dendritic cell differentiation and activation

Dendritic cells (DC) play a key role in the initiation of both antitumor immunity and immunological tolerance. It has been demonstrated that exposure to soluble factors produced by tumor cells modulates DC functions and induces tolerogenic DC differentiation. In this study, we investigated the effects of neuroblastoma cell line-derived soluble factors on DC differentiation. Monocytes isolated from healthy volunteers were incubated with interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor in the presence of culture supernatants from neuroblastoma cell lines. The culture supernatants from neuroblastoma cell lines, such as NLF and GOTO, partially blocked both downregulation of CD14 and upregulation of CD1a, and dramatically decreased IL-12 and tumor necrosis factor (TNF)-α production from mature DC, while no effect of SH-SY5Y cell supernatant was noted. In addition, IL-6 and IL-10 production from monocytes was increased by the supernatants of NLF and GOTO cells at 24 hours after incubation. Furthermore, we evaluated DC functions through stimulation of invariant natural killer T (iNKT) cells. α-Galactosylceramide-pulsed DC co-cultured with supernatants of NLF cells were unable to sufficiently stimulate iNKT cells. The decreased ability of iNKT cells to produce interferon (IFN)-γ after stimulation with neuroblastoma cell line supernatant-cultured DC was reversed by addition of IL-12. CD40 expression and IL-12 production in NLF-sup-treated DC were increased by addition of exogenous IFN-γ. These results indicate that tolerogenic DC are induced in the neuroblastoma tumor microenvironment and attenuate the antitumor effects of iNKT cells. Interactions between iNKT cells and αGalCer-pulsed DC have the potential to restore the immunosuppression of tolerogenic DC through IFN-γ production.

Positive & Negative Roles of Innate Effector Cells in Controlling Cancer Progression

Innate immune cells are active at the front line of host defense against pathogens and now appear to play a range of roles under non-infectious conditions as well, most notably in cancer. Establishing the balance of innate immune responses is critical for the “flavor” of these responses and subsequent adaptive immunity and can be either “good or bad” in controlling cancer progression. The importance of innate NK cells in tumor immune responses has already been extensively studied over the last few decades, but more recently several relatively mono- or oligo-clonal [i.e., (semi-) invariant] innate T cell subsets received substantial interest in tumor immunology including invariant natural killer T (iNKT), γδ-T and mucosal associated invariant T (MAIT) cells. These subsets produce high levels of various pro- and/or anti-inflammatory cytokines/chemokines reflecting their capacity to suppress or stimulate immune responses. Survival of patients with cancer has been linked to the frequencies and activation status of NK, iNKT, and γδ-T cells. It has become clear that NK, iNKT, γδ-T as well as MAIT cells all have physiological roles in anti-tumor responses, which emphasize their possible relevance for tumor immunotherapy. A variety of clinical trials has focused on manipulating NK, iNKT, and γδ-T cell functions as a cancer immunotherapeutic approach demonstrating their safety and potential for achieving beneficial therapeutic effects, while the exploration of MAIT cell related therapies is still in its infancy. Current issues limiting the full therapeutic potential of these innate cell subsets appear to be related to defects and suppressive properties of these subsets that, with the right stimulus, might be reversed. In general, how innate lymphocytes are activated appears to control their subsequent abilities and consequent impact on adaptive immunity. Controlling these potent regulators and mediators of the immune system should enable their protective roles to dominate and their deleterious potential (in the specific context of cancer) to be mitigated.

Significance of Frequencies, Compositions, and/or Antileukemic Activity of (DC-stimulated) Invariant NKT, NK and CIK Cells on the Outcome of Patients With AML, ALL and CLL

Invariant natural killer T (iNKT)/natural killer (NK)/cytokine-induced killer (CIK) cells are important for immune surveillance. (I) Novel combinations of antibody 6B11 (targeting the Vα24-Jα18-invariant T-cell receptor) with CD4/CD8/CD1d/Vα24 for iNKT subset detection and "T/NK cell-like"-iNKT subsets were defined. Compared with healthy peripheral blood mononuclear cells (MNC) (significantly) lower proportions of iNKT cells (6B11/6B11CD3/6B11CD161), NK cells (CD3CD56/CD3CD161), and CIK cells (CD3CD56/CD3CD161) were found in peripheral blood MNC from acute myeloid (AML)/acute myeloid, lymphoid (ALL)/chronic lymphoid leukemia (CLL) patients in acute disease stages. Subtyping of iNKT cells revealed (significantly) higher proportions of CD3 T cells and CD161 NK cells in AML/ALL/CLL expressing 6B11 compared with healthy MNC. Prognostic evaluations showed higher proportions of iNKT/NK/CIK cells in favorable AML subgroups (younger age, primary, no extramedullary disease, achievement/maintenance of complete remission) or adult ALL and CLL patients. (II) iNKT/NK/CIK cell frequencies increased after (vs. before) mixed lymphocyte cultures of T-cell-enriched immune reactive cells stimulated with MNC/whole blood with or without pretreatment with "cocktails" (dendritic cells generating methods/kits inducing blasts' conversion to leukemia-derived dendritic cells from AML patients). Individual "cocktails" leading to "highest" iNKT cell frequencies could be defined. Antileukemic blast lytic activity correlated significantly with frequencies of iNKT/NK/CIK cells. In summary healthy MNC show significantly more iNKT/NK/CIK cells compared with AML/ALL/CLL MNC, a shift in the iNKT cell composition is seen in healthy versus leukemic samples and iNKT/NK/CIK cell-proportions in AML/ALL/CLL MNC samples correlate with prognosis. "Cocktail"-treated AML blasts lead to higher iNKT/NK/CIK cell frequencies and samples with antileukemic activity show significantly higher frequencies of iNKT/NK/CIK cells. Proportions of iNKT/NK/CIK cells should regularly be evaluated in AML/ALL/CLL diagnosis panels for quantitative/prognostic estimation of individual patients' antileukemic potential and their role in dendritic cells/leukemia-derived dendritic cells triggered immune surveillance.

Multifaceted Role of Neuropilins in the Immune System: Potential Targets for Immunotherapy

Neuropilins (NRPs) are non-tyrosine kinase cell surface glycoproteins expressed in all vertebrates and widely conserved across species. The two isoforms, such as neuropilin-1 (NRP1) and neuropilin-2 (NRP2), mainly act as coreceptors for class III Semaphorins and for members of the vascular endothelial growth factor family of molecules and are widely known for their role in a wide array of physiological processes, such as cardiovascular, neuronal development and patterning, angiogenesis, lymphangiogenesis, as well as various clinical disorders. Intriguingly, additional roles for NRPs occur with myeloid and lymphoid cells, in normal physiological as well as different pathological conditions, including cancer, immunological disorders, and bone diseases. However, little is known concerning the molecular pathways that govern these functions. In addition, NRP1 expression has been characterized in different immune cellular phenotypes including macrophages, dendritic cells, and T cell subsets, especially regulatory T cell populations. By contrast, the functions of NRP2 in immune cells are less well known. In this review, we briefly summarize the genomic organization, structure, and binding partners of the NRPs and extensively discuss the recent advances in their role and function in different immune cell subsets and their clinical implications.

Natural Killer T Cells in Cancer Immunotherapy

Natural killer T (NKT) cells are specialized CD1d-restricted T cells that recognize lipid antigens. Following stimulation, NKT cells lead to downstream activation of both innate and adaptive immune cells in the tumor microenvironment. This has impelled the development of NKT cell-targeted immunotherapies for treating cancer. In this review, we provide a brief overview of the stimulatory and regulatory functions of NKT cells in tumor immunity as well as highlight preclinical and clinical studies based on NKT cells. Finally, we discuss future perspectives to better harness the potential of NKT cells for cancer therapy.