The phenotypic heterogeneity of human natural killer cells: presence of at least 48 different subsets in the peripheral blood

Harnessing natural killer cells for refractory/relapsed non-Hodgkin lymphoma: biological roles, clinical trials, and future prospective

Non-Hodgkin lymphomas (NHLs) are heterogeneous and are among the most common hematological malignancies worldwide. Despite the advances in the treatment of patients with NHLs, relapse or resistance to treatment is anticipated in several patients. Therefore, novel therapeutic approaches are needed. Recently, natural killer (NK) cell-based immunotherapy alone or in combination with monoclonal antibodies, chimeric antigen receptors, or bispecific killer engagers have been applied in many investigations for NHL treatment. The functional defects of NK cells and the ability of cancerous cells to escape NK cell-mediated cytotoxicity within the tumor microenvironment of NHLs, as well as the beneficial results from previous studies in the context of NK cell-based immunotherapy in NHLs, direct our attention to this therapeutic strategy. This review aims to summarize clinical studies focusing on the applications of NK cells in the immunotherapy of patients with NHL.

Feeder-free differentiation of human iPSCs into natural killer cells with cytotoxic potential against malignant brain rhabdoid tumor cells

Natural killer (NK) cells are cytotoxic immune cells that can eliminate target cells without prior stimulation. Human induced pluripotent stem cells (iPSCs) provide a robust source of NK cells for safe and effective cell-based immunotherapy against aggressive cancers. In this in vitro study, a feeder-free iPSC differentiation was performed to obtain iPSC-NK cells, and distinct maturational stages of iPSC-NK were characterized. Mature cells of CD56bright CD16bright phenotype showed upregulation of CD56, CD16, and NK cell activation markers NKG2D and NKp46 upon IL-15 exposure, while exposure to aggressive atypical teratoid/rhabdoid tumor (ATRT) cell lines enhanced NKG2D and NKp46 expression. Malignant cell exposure also increased CD107a degranulation markers and stimulated IFN-γ secretion in activated NK cells. CD56bright CD16bright iPSC-NK cells showed a ratio-dependent killing of ATRT cells, and the percentage lysis of CHLA-05-ATRT was higher than that of CHLA-02-ATRT. The iPSC-NK cells were also cytotoxic against other brain, kidney, and lung cancer cell lines. Further NK maturation yielded CD56-ve CD16bright cells, which lacked activation markers even after exposure to interleukins or ATRT cells - indicating diminished cytotoxicity. Generation and characterization of different NK phenotypes from iPSCs, coupled with their promising anti-tumor activity against ATRT in vitro, offer valuable insights into potential immunotherapeutic strategies for brain tumors.

Programmed Cell Death Pathways in Cholangiocarcinoma: Opportunities for Targeted Therapy

Cholangiocarcinoma is a highly aggressive cancer arising from the bile ducts. The limited effectiveness of conventional therapies has prompted the search for new approaches to target this disease. Recent evidence suggests that distinct programmed cell death mechanisms, namely, apoptosis, ferroptosis, pyroptosis and necroptosis, play a critical role in the development and progression of cholangiocarcinoma. This review aims to summarize the current knowledge on the role of programmed cell death in cholangiocarcinoma and its potential implications for the development of novel therapies. Several studies have shown that the dysregulation of apoptotic signaling pathways contributes to cholangiocarcinoma tumorigenesis and resistance to treatment. Similarly, ferroptosis, pyroptosis and necroptosis, which are pro-inflammatory forms of cell death, have been implicated in promoting immune cell recruitment and activation, thus enhancing the antitumor immune response. Moreover, recent studies have suggested that targeting cell death pathways could sensitize cholangiocarcinoma cells to chemotherapy and immunotherapy. In conclusion, programmed cell death represents a relevant molecular mechanism of pathogenesis in cholangiocarcinoma, and further research is needed to fully elucidate the underlying details and possibly identify therapeutic strategies.

NK Cells and Other Cytotoxic Innate Lymphocytes in Colorectal Cancer Progression and Metastasis

Colorectal cancer (CRC) is one of the most common malignancies and leading causes of cancer-related deaths worldwide. Despite its complex pathogenesis and progression, CRC represents a well-fitting example of how the immune contexture can dictate the disease outcome. The presence of cytotoxic lymphocytes, both CD8⁺ T cells and natural killer (NK) cells, represents a relevant prognostic factor in CRC and is associated with a better overall survival. Together with NK cells, other innate lymphocytes, namely, innate lymphoid cells (ILCs), have been found both in biopsies of CRC patients and in murine models of intestinal cancer, playing both pro- and anti-tumor activities. In particular, several type 1 innate lymphoid cells (ILC1) with cytotoxic functions have been recently described, and evidence in mice shows a role for both NK cells and ILC1 in controlling CRC metastasis. In this review, we provide an overview of the features of NK cells and the expanding spectrum of innate lymphocytes with cytotoxic functions. We also comment on both the described and the potential roles these innate lymphocytes can play during the progression of intestinal cancer leading to metastasis. Finally, we discuss recent advances in the molecular mechanisms underlying the functional regulation of cytotoxic innate lymphocytes in CRC.

Host protease activity classifies pneumonia etiology

Community-acquired pneumonia (CAP) has been brought to the forefront of global health priorities due to the COVID-19 pandemic. However, classification of viral versus bacterial pneumonia etiology remains a significant clinical challenge. To this end, we have engineered a panel of activity-based nanosensors that detect the dysregulated activity of pulmonary host proteases implicated in the response to pneumonia-causing pathogens and produce a urinary readout of disease. The nanosensor targets were selected based on a human protease transcriptomic signature for pneumonia etiology generated from 33 unique publicly available study cohorts. Five mouse models of bacterial or viral CAP were developed to assess the ability of the nanosensors to produce etiology-specific urinary signatures. Machine learning algorithms were used to train diagnostic classifiers that could distinguish infected mice from healthy controls and differentiate those with bacterial versus viral pneumonia with high accuracy. This proof-of-concept diagnostic approach demonstrates a way to distinguish pneumonia etiology based solely on the host proteolytic response to infection.

CITEMOXMBD: A flexible single-cell multimodal omics analysis framework to reveal the heterogeneity of immune cells

Simultaneous measurement of multiple modalities in single-cell analysis, represented by CITE-seq, is a promising approach to link transcriptional changes to cellular phenotype and function, requiring new computational methods to define cellular subtypes and states based on multiple data types. Here, we design a flexible single-cell multimodal analysis framework, called CITEMO, to integrate the transcriptome and antibody-derived tags (ADT) data to capture cell heterogeneity from the multi omics perspective. CITEMO uses Principal Component Analysis (PCA) to obtain a low-dimensional representation of the transcriptome and ADT, respectively, and then employs PCA again to integrate these low-dimensional multimodal data for downstream analysis. To investigate the effectiveness of the CITEMO framework, we apply CITEMO to analyse the cell subtypes of Cord Blood Mononuclear Cells (CBMC) samples. Results show that the CITEMO framework can comprehensively analyse single-cell multimodal samples and accurately identify cell subtypes. Besides, we find some specific immune cells that co-express multiple ADT markers. To better describe the co-expression phenomenon, we introduce the co-expression entropy to measure the heterogeneous distribution of the ADT combinations. To further validate the robustness of the CITEMO framework, we analyse Human Bone Marrow Cell (HBMC) samples and identify different states of the same cell type. CITEMO has an excellent performance in identifying cell subtypes and states for multimodal omics data. We suggest that the flexible design idea of CITEMO can be an inspiration for other single-cell multimodal tasks. The complete source code and dataset of the CITEMO framework can be obtained from https://github.com/studentiz/CITEMO.

Directly reprogrammed natural killer cells for cancer immunotherapy

Efficacious and accessible sources of natural killer (NK) cells would widen their use as immunotherapeutics, particularly for solid cancers. Here, we show that human somatic cells can be directly reprogrammed into NK cells with a CD56^brightCD16^bright phenotype using pluripotency transcription factors and an optimized reprogramming medium. The directly reprogrammed NK cells have strong innate-adaptive immunomodulatory activity and are highly potent against a wide range of cancer cells, including difficult-to-treat solid cancers and cancer stem cells. Both directly reprogrammed NK cells bearing a cancer-specific chimeric antigen receptor and reprogrammed NK cells in combination with antibodies competent for antibody-dependent cell-mediated cytotoxicity led to selective anticancer effects with augmented potency. The direct reprogramming of human somatic cells into NK cells is amenable to the production of autologous and allogeneic NK cells, and will facilitate the design and testing of cancer immunotherapies and combination therapies.

Uterine natural killer cells: from foe to friend in reproduction

BACKGROUND

Recurrent miscarriage and pre-eclampsia are common reproductive disorders, but their causes are often unknown. Recent evidence has provided new insight into immune system influences in reproductive disorders. A subset of lymphocytes of the innate immune system known as uterine natural killer (uNK) cells are now recognized as fundamental to achieving embryo implantation and successful pregnancy, but were initially attributed a bad reputation. Indeed, immune therapies have been developed to treat the 'exaggerated' immune response from uNK cells. These treatments have been based on studies of peripheral blood natural killer (pbNK) cells. However, uNK cells and pbNK cells have different phenotypic and functional characteristics. The functions of uNK cells are closely related to their interactions with the extravillous trophoblast cells (EVTs) and spiral arteries, which underlie an essential role in regulating vascular function, controlling trophoblast invasion and promoting placental development. EVTs express MHC molecules of class I HLA-C/E/G/F, while uNK cells express, among other receptors, killer cell immunoglobulin-like receptors (KIRs) that bind to HLA-C or CD94/NKG2A inhibitory receptors, and then bind HLA-E. Associations of certain KIR/HLA-C combinations with recurrent miscarriage, pre-eclampsia, and foetal growth restriction and the interactions between uNK cells, trophoblasts and vascular cells have led to the hypothesis that uNK cells may play a role in embryo implantation.

OBJECTIVE AND RATIONALE

Our objective was to review the evolution of our understanding of uNK cells, their functions, and their increasingly relevant role in reproduction.

SEARCH METHODS

Relevant literature through June 2020 was retrieved using Google Scholar and PubMed. Search terms comprised uNK cells, human pregnancy, reproductive failure, maternal KIR and HLA-C, HLA-E/G/F in EVT cells, angiogenic cytokines, CD56+ NK cells, spiral artery, oestrogen and progesterone receptors, KIR haplotype and paternal HLA-C2.

OUTCOMES

This review provides key insights into the evolving conceptualization of uNK cells, from their not-so-promising beginnings to now, when they are considered allies in reproduction. We synthesized current knowledge about uNK cells, their involvement in reproduction and their main functions in placental vascular remodeling and trophoblast invasion. One of the issues that this review presents is the enormous complexity involved in studying the immune system in reproduction. The complexity in the immunology of the maternal-foetal interface lies in the great variety of participating molecules, the processes and interactions that occur at different levels (molecular, cellular, tissue, etc.) and the great diversity of genetic combinations that are translated into different types of responses.

WIDER IMPLICATIONS

Insights into uNK cells could offer an important breakthrough for ART outcomes, since each patient could be assessed based on the combination of HLA and its receptors in their uNK cells, evaluating the critical interactions at the materno-foetal interface. However, owing to the technical challenges in studying uNK cells in vivo, there is still much knowledge to gain, particularly regarding their exact origin and functions. New studies using novel molecular and genetic approaches can facilitate the identification of mechanisms by which uNK cells interact with other cells at the materno-foetal interface, perhaps translating this knowledge into clinical applicability.

Expression of NK cell receptor ligands in primary colorectal cancer tissue in relation to the phenotype of circulating NK- and NKT cells, and clinical outcome

INTRODUCTION

Natural killer (NK) cells and natural killer T (NKT) cells are implicated in the development and progression of colorectal cancer (CRC). Tumor cells express NK cell receptor ligands that modulate their function. This study aimed to investigate the expression of such ligands in CRC in relation to the phenotype of circulating NK- and NKT cells, and clinical outcome.

METHODS

Primary tumor tissues were analyzed for protein expression of NK cell ligands using immunohistochemistry with automated image analysis in a cohort of 78 CRC patients. For 24 of the 78 patients, RNA expression of NK cell ligands was analyzed in primary tumor tissue using RNA sequencing. Receptor expression on circulating NK- and NKT cells was previously measured by us in 71 of the 78 patients using flow cytometry.

RESULTS

High Proliferating Cell Nuclear Antigen (PCNA) protein expression in the primary tumor associated with shorter disease-free survival (DFS) of CRC patients (P = 0.026). A trend was observed towards shorter DFS in CRC patients with above-median galectin-3 protein expression in the primary tumor (P = 0.055). High protein expression of galectin-3, CD1d, and human leukocyte antigen (HLA) class I, and high RNA expression of UL16-binding protein (ULBP)-1, -2, and -5, and HLA-E in the tumor tissue correlated with low expression of the corresponding receptors on circulating NK- or NKT cells (P < 0.05).

CONCLUSIONS

Galectin-3 and PCNA expression in the primary tumor may be prognostic biomarkers in CRC patients. Furthermore, our results suggest that NK cell receptor ligands expressed by tumor cells may modulate the phenotype of circulating NK- and NKT cells, and facilitate immune escape of metastasizing cells.

Regulatory T Cells in Pregnancy: It Is Not All About FoxP3

In pregnancy, the semi-allogeneic fetus needs to be tolerated by the mother's immune system. Regulatory T cells (Tregs) play a prominent role in this process. Novel technologies allow for in-depth phenotyping of previously unidentified immune cell subsets, which has resulted in the appreciation of a vast heterogeneity of Treg subsets. Similar to other immunological events, there appears to be great diversity within the Treg population during pregnancy, both at the maternal-fetal interface as in the peripheral blood. Different Treg subsets have distinct phenotypes and various ways of functioning. Furthermore, the frequency of individual Treg subsets varies throughout gestation and is altered in aberrant pregnancies. This suggests that distinct Treg subsets play a role at different time points of gestation and that their role in maintaining healthy pregnancy is crucial, as reflected for instance by their reduced frequency in women with recurrent pregnancy loss. Since pregnancy is essential for the existence of mankind, multiple immune regulatory mechanisms and cell types are likely at play to assure successful pregnancy. Therefore, it is important to understand the complete microenvironment of the decidua, preferably in the context of the whole immune cell repertoire of the pregnant woman. So far, most studies have focused on a single mechanism or cell type, which often is the FoxP3 positive regulatory T cell when studying immune regulation. In this review, we instead focus on the contribution of FoxP3 negative Treg subsets to the decidual microenvironment and their possible role in pregnancy complications. Their phenotype, function, and effect in pregnancy are discussed.

Immune Cell Subtypes and Cytokines in Lung Tumor Microenvironment: Influence of COPD

Background: The immune microenvironment plays a role in tumorigenesis. Chronic Obstructive Pulmonary Disease (COPD) is an independent risk factor for lung cancer (LC). We hypothesized that immune profile characterized by T regulatory (Treg), natural killer (NK), and plasma cells, as well as interleukin (IL)-10 and interferon-gamma, may differ within tumors of LC patients with/without COPD. Methods: Treg (anti-CD3 and anti-forkhead boxP3 antibodies), NK (anti-NCR1 antibody), IgG (anti-CD138-IgG antibody), IgA (anti-CD138-IgA antibody) using immunohistochemistry, and both IL-10 and interferon-gamma (ELISA) were quantified in tumor and non-tumor specimens (thoracotomy for lung tumor resection) from 33 LC–COPD patients and 20 LC-only patients. Results: Immune profile in tumor versus non-tumor specimens: Treg cell counts significantly increased in tumors of both LC and LC–COPD patients, while in tumors of the latter group, IgG-secreting plasma cells significantly decreased and IL-10 increased. No significant differences were seen in levels of NK cells, IgA-secreting cells, IgA/IgG, or interferon-gamma. Immune profile in tumors of LC–COPD versus LC: No significant differences were observed in tumors between LC–COPD and LC patients for any study marker. Conclusions: Immune cell subtypes and cytokines are differentially expressed in lung tumors, and the presence of COPD elicited a decline in IgG-secreting plasma cell levels but not in other cell types.

The effects of tumor resection and adjuvant therapy on the peripheral blood immune cell profile in patients with colon carcinoma

OBJECTIVE

The subset distribution and immunophenotype of circulating immune cells ("peripheral blood immune cell profile") may reflect tumor development and response to cancer treatment. In order to use the peripheral blood immune cell profile as biomarker to monitor patients over time, it is crucial to know how immune cell subsets respond to therapeutic interventions. In this study, we investigated the effects of tumor resection and adjuvant therapy on the peripheral blood immune cell profile in patients with colon carcinoma (CC).

METHODS

The subset distribution and immunophenotype of T cells (CD3⁺CD56^-), CD56^dim NK cells (CD3^-CD56^dim), CD56^bright NK cells (CD3^-CD56^bright) and NKT-like cells (CD3⁺CD56⁺) were studied in preoperative and postoperative peripheral blood mononuclear cell (PBMC) samples of 24 patients with CC by multiparameter flow cytometry. Changes in immunophenotype of circulating immune cells after tumor resection were studied in patients treated with and without (capecitabine-based) adjuvant therapy.

RESULTS

The NKT-like cell (% of total PBMCs) and CD8⁺ T cell (% of total T cells) populations expanded in the peripheral blood of non-adjuvant-treated CC patients after surgery. NK- and NKT-like cells showed upregulation of activating receptors and downregulation of inhibitory receptors in non-adjuvant-treated CC patients after surgery. These changes were not observed in the peripheral blood of adjuvant-treated CC patients.

CONCLUSIONS

Our results suggest tumor-induced suppression of NK- and NKT-like cells in CC patients, an effect that could not be detected after tumor resection. In contrast, adjuvant therapy maintained tumor-induced immunosuppression of NK- and NKT-like cells in CC patients.

CD8-Specific Designed Ankyrin Repeat Proteins Improve Selective Gene Delivery into Human and Primate T Lymphocytes

Adoptive T cell immunotherapy in combination with gene therapy is a promising treatment concept for chronic infections and cancer. Recently, receptor-targeted lentiviral vectors (LVs) were shown to enable selective gene transfer into particular types of lymphocytes both in vitro and in vivo. This approach might facilitate the genetic engineering of a patient's own T lymphocytes, possibly even shifting this concept from personalized medicine to an off-the shelf therapy in future. Here, we describe novel high-affinity binders for CD8 consisting of designed ankyrin repeat proteins (DARPins), which were selected to bind to the CD8 receptor of human and nonhuman primate (NHP) cells. These binders were identified by ribosome display screening of DARPin libraries using recombinant human CD8 followed by receptor binding analysis on primary lymphocytes. CD8-targeted LVs (CD8-LVs) were then generated that delivered genes exclusively and specifically to human and NHP T lymphocytes by using the same targeting domain. These CD8-LVs were as specific for human T lymphocytes as their single-chain variable fragment-based counterpart, but they could be produced to higher titers. Moreover, they were superior in transducing cytotoxic T cells both in vitro and in vivo when equal particle numbers were applied. Since the here described CD8-LVs transduced primary T lymphocytes from NHP and human donors equally well, they offer the opportunity for preclinical studies in different animal models including large animals such as NHPs without the need for modifications in vector design.

A novel population of memory-activated natural killer cells associated with low parasitaemia in Plasmodium falciparum-exposed sickle-cell trait children

Objectives

The sickle‐cell trait phenotype is associated with protection from malaria. Multiple molecular mechanisms have been proposed to explain this protection, but the role of the host immune system has been poorly investigated. We hypothesised that cellular immunity to malaria may develop differently in sickle‐cell trait children (HbAS) and children with normal haemoglobin (HbAA) repeatedly exposed to Plasmodium falciparum (Pf).

Methods

Paired samples collected prior to the Pf transmission season and during the first malaria episode of the ensuing transmission season from HbAS and HbAA children were analysed by multiplex bead‐based assay and comprehensive multi‐dimensional flow cytometry profiling.

Results

Cellular immune profiles were enriched in HbAS relative to HbAA children before the start of the Pf transmission season, with a distinct NK subset. These cells were identified as a novel subset of memory‐activated NK cells characterised by reduced expression of the ecto‐enzyme CD38 as well as co‐expression of high levels of HLA‐DR and CD45RO. The frequency of this NK subset before the transmission season was negatively correlated with parasite density quantified during the first malaria episode of the ensuing transmission season. Functional assessment revealed that these CD38^dim CD45RO⁺ HLA‐DR⁺ NK cells represent a important source of IFN‐γ.

Conclusion

Our data suggest that this novel memory‐activated NK cell subset may contribute to an accelerated and enhanced IFN‐γ‐mediated immune response and to control of parasite density in individuals with the sickle‐cell trait. This distinct cellular immune profile may contribute to predispose HbAS children to a relative protection from malaria.

Respiratory Viral Infection Alters the Gut Microbiota by Inducing Inappetence

Respiratory viral infections are extremely common, but their impacts on the composition and function of the gut microbiota are poorly understood. We previously observed a significant change in the gut microbiota after viral lung infection. Here, we show that weight loss during respiratory syncytial virus (RSV) or influenza virus infection was due to decreased food consumption, and that the fasting of mice altered gut microbiota composition independently of infection. While the acute phase tumor necrosis factor alpha (TNF-α) response drove early weight loss and inappetence during RSV infection, this was not sufficient to induce changes in the gut microbiota. However, the depletion of CD8+ cells increased food intake and prevented weight loss, resulting in a reversal of the gut microbiota changes normally observed during RSV infection. Viral infection also led to changes in the fecal gut metabolome, with a significant shift in lipid metabolism. Sphingolipids, polyunsaturated fatty acids (PUFAs), and the short-chain fatty acid (SCFA) valerate were all increased in abundance in the fecal metabolome following RSV infection. Whether this and the impact of infection-induced anorexia on the gut microbiota are part of a protective anti-inflammatory response during respiratory viral infections remains to be determined.IMPORTANCE The gut microbiota has an important role in health and disease: gut bacteria can generate metabolites that alter the function of immune cells systemically. Understanding the factors that can lead to changes in the gut microbiome may help to inform therapeutic interventions. This is the first study to systematically dissect the pathway of events from viral lung infection to changes in gut microbiota. We show that the cellular immune response to viral lung infection induces inappetence, which in turn alters the gut microbiome and metabolome. Strikingly, there was an increase in lipids that have been associated with the resolution of disease. This opens up new paths of investigation: first, what is the (presumably secreted) factor made by the T cells that can induce inappetence? Second, is inappetence an adaptation that accelerates recovery from infection, and if so, does the microbiome play a role in this?

Characterization of circulating T-, NK-, and NKT cell subsets in patients with colorectal cancer: the peripheral blood immune cell profile

Objective

As the development and progression of colorectal cancer (CRC) are known to be affected by the immune system, cell subsets such as T cells, natural killer (NK) cells, and natural killer T (NKT) cells are considered interesting targets for immunotherapy and clinical biomarker research. Until now, the role of systemic immune profiles in tumor progression remains unclear. In this study, we aimed to characterize the immunophenotype of circulating T cells, NK cells, and NKT-like cells in patients with CRC, and to subsequently correlate these immunophenotypes to clinical follow-up data.

Methods

Using multiparameter flow cytometry, the subset distribution and immunophenotype of T cells (CD3⁺CD56⁻), CD56^dim NK cells (CD3⁻CD56^dim), CD56^bright NK cells (CD3⁻CD56^bright), and NKT-like (CD3⁺CD56⁺) cells were investigated in peripheral blood mononuclear cell (PBMC) samples from 71 CRC patients and 19 healthy donors.

Results

CRC patients showed profound differences in immune cell subset distribution and their immunophenotype compared to healthy donors, as characterized by increased percentage of regulatory T cells, and reduced expression level of the natural cytotoxicity receptors NKp44 and NKp46 on both CD56^dim NK cells and NKT-like cells. Finally, we showed in a multivariate analysis that above-median percentage of CD16⁺ NKT-like cells was independently associated with shorter disease-free survival in CRC patients.

Conclusion

The altered phenotype of circulating immune cell subsets in CRC and its association with clinical outcome highlight the potential use of PBMC subsets as prognostic biomarkers in CRC, thereby contributing to better insight into the role of systemic immune profiles in tumor progression.

Electronic supplementary material

The online version of this article (10.1007/s00262-019-02343-7) contains supplementary material, which is available to authorized users.

Proteomic definition of human mucosal-associated invariant T cells determines their unique molecular effector phenotype

Mucosal-associated invariant T cells (MAIT) constitute the most abundant anti-bacterial CD8⁺ T-cell population in humans. MR1/TCR-activated MAIT cells were reported to organize cytotoxic and innate-like responses but knowledge about their molecular effector phenotype is still fragmentary. Here, we have examined the functional inventory of human MAIT cells (CD3⁺ Vα7.2⁺ CD161⁺ ) in comparison with those from conventional non-MAIT CD8⁺ T cells (cCD8⁺ ) and NK cells. Quantitative mass spectrometry characterized 5500 proteins of primary MAIT cells and identified 160 and 135 proteins that discriminate them from cCD8⁺ T cells and NK cells donor-independently. Most notably, MAIT cells showed a unique exocytosis machinery in parallel to a proinflammatory granzyme profile with high levels of the granzymes A, K, and M. Furthermore, 24 proteins were identified with highest abundances in MAIT cells, including CD26, CD98, and L-amino-oxidase (LAAO). Among those, expression of granzyme K and CD98 were validated as MAIT-specific with respect to non-MAIT CD8⁺ effector subsets and LAAO was found to be recruited together with granzymes, perforin, and CD107a at the immunological synapse of activated MAIT cells. In conclusion, this study complements knowledge on the molecular effector phenotype of MAIT cells and suggest novel immune regulatory functions as part of their cytotoxic responses.

Role of natural killer cells in lung cancer

PURPOSE

One of the key immune cells involved in the pathogenesis of lung cancer is natural killer (NK) cells and these cells are novel targets for therapeutic applications in lung cancer. The purpose of this review is to summarize the current literature on lung cancer pathogenesis with a focus on the interaction between NK cells and smoking, how these factors are related to the pathogenesis of lung cancer and how NK cell-based immunotherapy effect lung cancer survival.

METHODS

The relevant literature from PubMed and Medline databases is reviewed in this article.

RESULTS

The cytolytic potential of NK cells are reduced in lung cancer and increasing evidence suggests that improving NK cell functioning may induce tumor regression. Recent clinical trials on NK cell-based novel therapies such as cytokines including interleukin (IL)-15, IL-12 and IL-2, NK-92 cell lines and allogenic NK cell immunotherapy showed promising results with less adverse effects on the lung cancer survival.

CONCLUSIONS

The NK cell targeting strategy has not yet been approved for lung cancer treatment. More clinical studies focusing on the role of NK cells in lung cancer pathogenesis are warranted to develop novel NK cell-based therapeutic approaches for the treatment of lung cancer.

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 CD56bright and CD56dim 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.

Terminal Differentiation of CD56(dim)CD16(+) Natural Killer Cells Is Associated with Increase in Natural Killer Cell Frequencies After Antiretroviral Treatment in HIV-1 Infection

HIV-1 infection results in immunological abnormalities of natural killer (NK) cells such as disturbed distribution of NK cell subsets and downmodulation of activating and upregulation of inhibitory receptors thereby diminishing NK cell killing capacity and cytokine secretion. Antiretroviral treatment (ART) is known to restore phenotype and functions of NK cells. However, the effects of ART on NK cell terminal differentiation, activation, and disturbed distribution have not been studied yet longitudinally. Here, we analyzed the effects of ART on these parameters of peripheral blood NK cells in a longitudinal as well as in a cross-sectional study. We observed that expanded CD56(-)CD16(+) NK cell frequency is inversely correlated with the frequency of CD56(dim)CD16(+) NK cells in treatment-naive HIV-1 patients. Loss of CD56(dim)CD16(+) and expansion of CD56(-)CD16(+) NK cells again restore to the levels of healthy controls after ART. Enhanced immune activation of different NK cell subsets is partially restored after ART. Terminal differentiation of CD56(dim)CD16(+) NK cells is enhanced after ART as measured by CD57 expression. Frequencies of CD57(+)CD56(dim)CD16(+) NK cells are directly correlated with the frequencies of total NK cells suggesting that an increase in the frequencies of CD57(+)CD56(dim)CD16(+) NK cells is reflected by increased frequencies of total NK cells after ART. Taken together these data demonstrate that ART has an effect on the immune restoration of NK cells and is enhanced in the terminal differentiation of CD56(dim)CD16(+) NK cells, which is associated with increased frequencies of total NK cells after ART.

High frequencies of polyfunctional CD8+ NK cells in chronic HIV-1 infection are associated with slower disease progression

Natural killer (NK) cells are effector and regulatory innate immune cells and play a critical role in the first line of defense against various viral infections. Although previous reports have indicated the vital contributions of NK cells to HIV-1 immune control, nongenetic NK cell parameters directly associated with slower disease progression have not been defined yet. In a longitudinal, retrospective study of 117 untreated HIV-infected subjects, we show that higher frequencies as well as the absolute numbers of CD8(+) CD3(-) lymphocytes are linked to delayed HIV-1 disease progression. We show that the majority of these cells are well-described blood NK cells. In a subsequent cross-sectional study, we demonstrate a significant loss of CD8(+) NK cells in untreated HIV-infected individuals, which correlated with HIV loads and inversely correlated with CD4(+) T cell counts. CD8(+) NK cells had modestly higher frequencies of CD57-expressing cells than CD8(-) cells, but CD8(+) and CD8(-) NK cells showed no differences in the expression of a number of activating and inhibiting NK cell receptors. However, CD8(+) NK cells exhibited a more functional profile, as detected by cytokine production and degranulation.

IMPORTANCE

We demonstrate that the frequency of highly functional CD8(+) NK cells is inversely associated with HIV-related disease markers and linked with delayed disease progression. These results thus indicate that CD8(+) NK cells represent a novel NK cell-derived, innate immune correlate with an improved clinical outcome in HIV infection.

Natural killer cells in patients with allergic diseases

Natural killer (NK) cells not only exert cytotoxic activity against tumor cells or infected cells but also act to regulate the function of other immune cells through secretion of cytokines and chemokines or cell contact-dependent mechanisms. NK cells are able to polarize in vitro into 2 functional distinct subsets, NK1 or NK2 cells, which are analogous to the T-cell subsets TH1 or TH2. In addition, a regulatory NK cell subset has been described that secretes IL-10, shows antigen-specific T-cell suppression, and suppresses IgE production. Although it has been demonstrated that NK cells play important roles in autoimmunity, cancer, transplantation, and pregnancy, the role of NK cells in allergy has not been extensively discussed. This review aims to discuss our understanding of NK cells and NK cell subsets in allergic inflammation and IgE regulation.

Peripheral blood NK cells from breast cancer patients are tumor-induced composite subsets

Human NK lymphocytes are involved in antitumor immunity. The therapeutic potential of this population against cancers has stimulated their study and led to the discovery of several NK cell subsets, each of which is endowed with different immunoregulatory functions. We have previously reported that NK cell functions are profoundly altered in advanced breast cancer patients. In this study, we show that these tumor-mediated alterations also variably affect NK cell subsets. We found that in addition to the known human CD56(dim)CD16(+), CD56(bright)CD16(-), and CD56(-)CD16(+) NK cell subsets, two additional subsets, namely the CD56(bright)CD16(+) and CD56(dim)CD16(-) subsets, were increased in the peripheral blood of patients with advanced invasive breast cancers. These subsets corresponded to the main two subsets found at the tumor site. The extensive phenotype of these subsets revealed an "à la carte" pattern of expression for the various NK receptors, functional molecules, adhesion molecules, and chemokine receptors, depending on the subset. We next compared these subsets to known NK cell populations endowed with specific phenotypic characteristics, but also with functional properties. Our data show that advanced breast cancer patients have an increased proportion of more immature and noncytotoxic NK cell subsets in their peripheral blood, which might account for at least part of the low cytotoxic functions observed in these patients. They reveal a major heterogeneity and plasticity of the NK cell compartment, which are both tightly linked to the microenvironment. The identification of NK cell subsets endowed with particular functional capabilities might help monitor residual antitumor NK cell-mediated responses in breast cancer patients.

In vitro modulation of natural killer activity of human peripheral blood mononuclear cells against prostate tumor cell line

OBJECTIVE

Natural killer (NK) cells have long been known to be involved in the recognition and lysis of tumor cells but the mechanisms contributing to deficient NK activity in patients with cancer remains unclear. Manipulation of them is likely essential to the success of cancer immunotherapy protocols although optimal stimulation and maintenance of NK activity remains elusive. Here we studied the stimulatory effects of PHA and K562, on NK activity of human peripheral blood mononuclear cells (PBMCs).

MATERIALS AND METHODS

The NK activity of PBMCs against DU-145 was determined with 51Cr-release assay. The PBMCs were stimulated with PHA, either on one occasion or repetitively on three occasions (1-PHA-PBMC or 3-PHA-PBMC, respectively), and were incubated with irradiated K562 (iK562). The expression of CD56, NKG2D and MICA/B were detected on PBMCs and cell lines with flow cytometry.

RESULTS

PHA stimulation increased the proportion of CD56+ cells and upregulated NKG2D expression on 1-PHA-PBMC and 3-PHA-PBMC, but co-incubation with iK562 decreased NKG2D expression on 1-PHA-PBMC without change of NKG2D expression on the 3-PHA-PBMC. NK activity of 1-PHA-PBMC appeared to decrease with co-incubation with iK562 compared to a significant increase in activity of 3-PHA-PBMC. A similar increase in interferon-γ (IFN-γ) secretion from 3-PHA-PBMC was demonstrated compared to 1-PHA-PBMC.

DISCUSSION AND CONCLUSION

Our results demonstrated that varying the mitogen exposure to PBMCs affect the influence of iK562 on NK activity. This effect appeared to be unrelated to the subsequent expression of NKG2D or IFN-γ secretion. These results may be beneficial in the development of future cancer immunotherapy protocols.

Effects of IL-2 on MMP expression in freshly isolated human NK cells and the IL-2-independent NK cell line YT

Interleukin-2 is an important activation factor for natural killer (NK) cells but its effect on NK cell matrix metalloproteinases (MMP) production and matrix degradation is less well investigated. We have used freshly isolated human NK cells and the IL-2-independent NK cell line, YT, to investigate the effects of IL-2 stimulation on NK cell invasion of Matrigel and on MMP expression and production. In YT cells, we found opposing early and late effects of IL-2 stimulation with an early (2 h) increase in MMP-9 protein level and enhanced migration in the Matrigel invasion assay and by 30 hours a decreased mRNA expression of MMP-2, MMP-9, MMP-13, MT3-MMP, and MT6-MMP. We also found a preculture period of 48 hours with IL-2 to negatively affect YT cell migration. We furthermore found that freshly isolated human NK cells Matrigel invasion was MMP-dependent and it increased in response to IL-2. Importantly, in freshly isolated human NK cells we did not see a downregulation of MMPs after 24 hours IL-2 stimulation, but instead a significant upregulation of MT6-MMP mRNA. Because of the cellular localisation of MT6-MMP, which ensures a focalized proteolytic activity, and its high expression compared with the other MMPs in freshly isolated human NK cells makes it of interest to study further.

Phenotypic and functional heterogeneity of natural killer cells from umbilical cord blood mononuclear cells

Natural killer cells (NK) from umbilical cord blood (CB) play an important role in allogeneic stem cell transplantation and defending infections of newborn. Based on the surface expression of CD56 and CD16 or inhibitory and activatory receptors, NK cells could be subdivided into various subsets with distinct functions. To investigate the biological characterization of NK subsets, the phenotypes and intracellular proteins in freshly isolated CB NK subsets were analyzed at the single cell level by flow cytometry in current study. The production of IFN-gamma and cytotoxicity against K562 target cells were also evaluated after stimulation with IL-12. The results showed that NK cells from CB could be divided into four subsets on the basis of CD56 and CD16 expression. Interestingly, CB NK cells expressed CD45RA but not CD45RO molecules that is similar to the naïve T cells. Moreover, CD27, a memory T cell marker, highly expressed on CD56(hi)CD16- NK cells. The killing-associated molecules, NKG2A, NKG2D, CD95 and the intracellular granzyme B and perforin were heterogeneously expressed among the 4 subsets. Addition of IL-12 into cultures resulted in the induction of IFN-gamma expression by CD56(hi)CD16- and CD56(lo)CD16- subsets and the enhancement of NK cytolytic activity. Taken together, this study elucidated the heterogeneity in phenotypes and biological functions of CB NK cells.

Phenotypically and functionally distinct subsets of natural killer cells in human PBMCs

Human natural killer (NK) cells are one major component of lymphocytes that mediate early protection against viruses and tumor cells, and play an important role in immune regulatory functions. In this study, we demonstrated that human NK cells could be divided into four subsets, CD56hi CD16(-), CD56lo CD16(-), CD56+CD16+ and CD56(-)CD16+, based on the expression of cell surface CD56 and CD16 molecules. Phenotypic analysis of NK cell subsets indicated that the expression of activation markers, adhesion molecules, memory cell markers, inhibitory and activating receptors, and intracellular proteins (granzyme B and perforin) were heterogeneous. Following interleukin (IL)-2 stimulation, interferon-gamma was preferentially produced by CD56+CD16(-) NK cells and this subset showed more proliferative capacity. The cytolytic activity of both CD56+CD16(-) and CD56+/-CD16+ subsets could be augmented in response to IL-2. The data provided a new definition for NK cell subsets demonstrating their phenotypic and functional diversity and possible stage of NK cell differentiation in peripheral blood.

Genomic analysis of CD8+ NK/T cell line, 'SRIK-NKL', with array-based CGH (aCGH), SKY/FISH and molecular mapping

We performed aCGH, SKY/FISH, molecular mapping and expression analyses on a permanent CD8+ NK/T cell line, 'SRIK-NKL' established from a lymphoma (ALL) patient, in attempt to define the fundamental genetic profile of its unique NK phenotypes. aCGH revealed hemizygous deletion of 6p containing genes responsible for hematopoietic functions. The SKY demonstrated that a constitutive reciprocal translocation, rcpt(5;14)(p13.2;q11) is a stable marker. Using somatic hybrids containing der(5) derived from SRIK-NKL, we found that the breakpoint in one homologue of no. 5 is located upstream of IL7R and also that the breakpoint in no. 14 is located within TRA@. The FISH analysis using a BAC which contains TRA@ and its flanking region further revealed a approximately 231kb deletion within 14q11 in the der(5) but not in the normal homologue of no. 14. The RT-PCR analysis detected mRNA for TRA@ transcripts which were extending across, but not including, the deleted region. IL7R was detected at least at mRNA levels. These findings were consistent with the immunological findings that TRA@ and IL7R are both expressed at mRNA levels and TRA@ at cytoplasmic protein levels in SRIK-NKL cells. In addition to rcpt(5;14), aCGH identified novel copy number abnormalities suggesting that the unique phenotype of the SRIK-NKL cell line is not solely due to the TRA@ rearrangement. These findings provide supportive evidence for the notion that SRIK-NKL cells may be useful for studying not only the function of NK cells but also genetic deregulations associated with leukemiogenesis.

Impact of immune parameters on long-term survival in metastatic renal cell carcinoma

PURPOSE

The purpose of this study was to evaluate the impact of immunologic prognostic factors in combination with established clinical prognostic factors in patients with metastatic renal cell carcinoma (mRCC).

PATIENTS AND METHODS

A total of 120 consecutive patients with mRCC received interleukin-2 (IL-2) -based immunotherapy. Baseline tumor biopsies were available from 85 of these patients. Potential prognostic factors were analyzed by univariate and multivariate analyses.

RESULTS

Multivariate analysis (N = 120) identified high lactate dehydrogenase, lymph node metastases, low hemoglobin, low Karnofsky performance status, and bone metastases as independent poor prognostic clinical factors. The impact of these clinical factors has been demonstrated by others. Multivariate analysis (n = 85) also identified a high blood neutrophil count (> 6.0 x 10(9)/L; hazard ratio, 2.0; P = .015), the presence of intratumoral neutrophils (> 0 cells/mm2 tumor tissue; hazard ratio, 2.3; P = .001), and low intratumoral CD57+ natural killer cell count (< 50 cells/mm2 tumor tissue; hazard ratio, 2.1; P = .01) as independent poor prognostic immunologic factors. These three independent immunologic parameters had significant discriminatory power as supplemental risk factors in prognostic models based on the clinical risk factors, identifying subgroups within the favorable clinical group with estimated 5-year survival rates of 60%, 25%, and 0%, respectively. These findings were apparent in both our own prognostic model and in an extended Memorial Sloan-Kettering Cancer Center (New York, NY) prognostic model.

CONCLUSION

This study points on five clinical and three supplemental immunologic independent prognostic factors of survival in patients with mRCC receiving IL-2.

NK Cell Receptors as Tools in Cancer Immunotherapy

Natural killer (NK) cells were identified 30 years ago based on their ability to "spontaneously" kill tumor cells. The basis for NK cell recognition and activation is due to a variety of receptors that bind to specific ligands on tumor cells and normal cells. Some of these receptors have the ability to inhibit NK cell function, and other receptors activate NK cell function. Therapeutic strategies for cancer therapy are being developed based on preventing NK cell inhibition or using NK cell receptors to activate NK cells or T cells. There are intriguing clinical data from studies of bone marrow transplantation that support the idea that preventing NK cell inhibition by human leukocyte antigen (HLA) class I molecules can be a means to promote graft-versus-leukemia (GvL) effects and limit graft-versus-host disease (GvHD) in acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) patients. Experimental findings also support the blockade of NK cell inhibitory receptors as a way to protect against leukemia relapse. It may be possible to use our knowledge of NK cell activating receptors and their ligands to immunize patients with modified tumor cells to promote beneficial NK cell responses and development of host antitumor cytotoxic T lymphocytes (CTLs). Finally, new data support the idea of using modified NK cell receptors as a means to target patients' T cells against their own tumor cells and induce long-term immunity against them. Tumors are essentially tissues that have overcome normal regulation mechanisms, and therefore the ability to distinguish normal cells from abnormal cells is a key part of selectively attacking tumor cells. NK cells have various receptor systems designed to recognize infected and abnormal cells. Understanding NK cell receptors and their recognition mechanisms provides new tools for the development of immunotherapies against cancer.

Natural killer cells in human health and disease

Natural killer (NK) cells are lymphocytes of the innate immune system that are critical in host defense and immune regulation. They are activated or inhibited through the ligation of germline-encoded receptors and are involved in mediating cytotoxicity, in producing cytokines and in providing co-stimulation to cells of the adaptive immune system. NK cells play important roles in viral infections, autoimmunity, pregnancy, cancer and bone marrow transplantation. This review highlights recent developments in the understanding of the role of human NK cells in health and disease.

Intrinsic abnormalities of lymphocyte counts in children with down syndrome

OBJECTIVE

Down syndrome (DS) is associated with an increased frequency of infections, hematologic malignancies, and autoimmune diseases, suggesting that immunodeficiency is an integral part of DS that contributes significantly to the observed increased morbidity and mortality. We determined the absolute counts of the main lymphocyte populations in a large group of DS children to gain further insight into this immunodeficiency.

STUDY DESIGN

In a large group of children with DS (n = 96), the absolute numbers of the main lymphocyte subpopulations were determined with 3-color immunophenotyping using the lysed whole-blood method. The results were compared with previously published data in healthy children without DS.

RESULTS

In healthy children with DS, the primary expansion of T and B lymphocytes seen in healthy children without DS in the first years of life was severely abrogated. The T- lymphocyte subpopulation counts gradually reached more normal levels with time, whereas the B- lymphocyte population remained severely decreased, with 88% of values falling below the 10th percentile and 61% below the 5th percentile of normal.

CONCLUSIONS

The diminished expansion of T and B lymphocytes strongly suggests that a disturbance in the adaptive immune system is intrinsically present in DS and is not a reflection of precocious aging. Thymic alterations have been described in DS that could explain the decreased numbers of T lymphocytes, but not the striking B lymphocytopenia, seen in these children.

Innate and adaptive immunity in female genital tract: cellular responses and interactions

The mucosal immune system in the female reproductive tract (FRT) has evolved to meet the unique requirements of dealing with sexually transmitted bacterial and viral pathogens, allogeneic spermatozoa, and the immunologically distinct fetus. Analysis of the FRT indicates that the key cells of the innate and adaptive immune systems are present and functionally responsive to antigens. Acting through Toll-like receptors in the Fallopian tubes, uterus, cervix, and in the vagina, epithelial cells, macrophages, natural killer cells, and neutrophils confer protection through the production of chemokines and cytokines, which recruit and activate immune cells, as well as bactericidal and virucidal agents, which confer protection at times when adaptive immunity is downregulated by sex hormones to meet the constraints of procreation. The overall goal of this paper is to define the innate immune system in the FRT and, where possible, to define the regulatory influences that occur during the menstrual cycle that contribute to protection from and susceptibility to potential pathogens. By understanding the nature of this protection and the ways in which innate and adaptive immunity interact, these studies provide the opportunity to contribute to the foundation of information essential for ensuring reproductive health.

Four-color staining combining fluorescence and brightfield microscopy for simultaneous immune cell phenotyping and localization in tumor tissue sections

Immune-cell infiltration is frequently seen within human solid tumors. A detailed phenotypic analysis of these cells may aid in the understanding of an antitumor immune response. Standard hematoxylin/eosin and conventional immunohistochemical stainings are helpful, but have major limitations in the number of markers that can be identified and localized per tissue section. Therefore, we developed a combined fluorescence and brightfield microscopic technique by using both immunofluorescence and immunogold-silver methods, thereby discriminating three different leukocyte markers plus one tumor marker simultaneously in a single section. This enabled us to study both phenotype and location of infiltrating immune cells in colorectal tumors. We used a two-step staining in which primary and secondary antibodies were selected for minimal cross-reactivity. Furthermore, the secondary fluorescent antibody conjugates were selected for minimal spectral overlap. For computer-assisted analysis the brightfield microscopy image was combined with the fluorescence microscopy images. This combination of techniques provides a powerful tool for detailed multiparameter microscopic analysis of formalin-fixed, paraffin-embedded tissue sections in general and for tumor-immune cell infiltration in particular.

Establishment and characterization of SRIK-NKL: a novel CD8+ natural killer/T cell line derived from a patient with leukemic phase of acute lymphoblastic lymphoma

The distinction between T cells and NK cells is difficult, and becoming more complex, as the diversity of the human lymphocyte repertoire is evident. We report the establishment of a permanent CD8+ NK/T cell line (SRIK-NKL) from a patient with leukemic phase of acute lymphoblastic lymphoma having characteristics of both NK and T cells, and extensively describe its phenotype, including cytotoxic activity, NK cell receptor expression, and other molecules critical for immune function. We further compare SRIK-NKL to other available NK/NK-T cell lines. SRIK-NKL may be useful for studying NK cell development, functions, and modulation, leading to novel strategies for treatment of autoimmune disease, infection, and cancer.

Immune system and prognosis in colorectal cancer: a detailed immunohistochemical analysis

The efficacy of tumor cell-immune cell interactions depends on a number of factors, for example, the expression of HLA-I on tumor cells, the type of immune cell, the accessibility of tumor cells for immune cells and the expression of immunogenic epitopes. We assessed infiltration of CD4+, CD8+, CD56+ and CD57+ cells in the tumor epithelium, tumor stroma and advancing tumor margin of 93 colorectal carcinomas and correlated this to clinicopathological parameters, the expression of HLA-A and HLA-B/C on tumor cells, the presence of a basal membrane (BM)-like structure surrounding tumor nodules and the presence of microsatellite instability/mutator phenotype (absent MLH-1 expression). The median intraepithelial CD4+, CD8+, CD56+ and CD57+ cell infiltrations were 3, 23, 0 and 0 cells/mm(2) tumor, respectively. HLA-A/BC expression by tumor cells was normal in 28/43%, heterogeneous in 59/48% and absent in 13/9% of the cases. A BM-like structure surrounding the tumor nodules was absent, present and thick in 47, 38 and 15% of the cases. Six cases lost MLH1 expression. There was a positive correlation between leukocyte infiltration in the three compartments for CD4+, CD8+, CD56+ (partly) and CD57+ (all P<0.05) cell infiltration. Intraepithelial CD8+ cell infiltration inversely correlated with HLA-A (P=0.04) and HLA-B/C expression (P=0.04). Intraepithelial CD57+ cell infiltration inversely correlated with HLA-B/C expression (P=0.04). Moreover, intraepithelial infiltration of CD8+ and CD57+ cells was inversely correlated to the presence of a BM-like structure (P=0.003 and 0.04, respectively). Uni- and multivariate analyses showed that a lower tumor stage (P=0.004) and marked infiltration of CD8+ (P=0.04) and CD57+ cells (P=0.05) at the advancing tumor margin were independent prognostic factors for a longer disease-free survival. Loss of MLH1 expression was correlated with a significantly higher intraepithelial CD8+ and CD57+ cell infiltration. We conclude that infiltration of CD8+ and CD57+ cells are important prognostic factors in colorectal cancer. However, their interaction with tumor cells is inversely correlated to the presence of HLA-I on tumor cells and a thick BM-like structure around tumor islets. Our data indicate that NK cells might play an important role in the immune surveillance in colorectal cancer patients.

A flow-cytometric NK-cytotoxicity assay adapted for use in rat repeated dose toxicity studies

A recent regulatory document for immunotoxicity testing of new pharmaceutical drugs includes cytotoxic natural killer (NK)-cell function as a required parameter in repeated dose toxicity studies. The classical 51Cr-release assay is the conventional test for cytotoxicity testing but several drawbacks with this assay has increased the demand for new reliable test systems.Here, we describe the optimisation of a flow-cytometric cytotoxicity assay especially adapted for regulatory rat studies in drug development. The test principle is based on target cell labelling with 5-(6)-carboxy-fluorescein succinimidyl ester (CFSE) and subsequent DNA-labelling with propidium iodide (PI) for identification of target cells with compromised cell membranes. The results are expressed as percentage of dead targets on a cell-to-cell basis. The final format of the assay includes 0.5ml peripheral blood, 1.25x10(5) effector cells per sample, and collection of 500 target events by flow-cytometry. When NKR-P1+ cells were removed from the effector cell population by magnetic depletion the relative proportion decreased from 6 to 0.08%. The corresponding cytotoxic activity decreased from 68 to 8%. Also, the cytotoxic activity showed a significant and positive correlation with the proportion of NK-cells present in the effector cell suspension. Thus, the cytotoxicity measured is almost exclusively exerted by NK-cells. The current flow-cytometric test benefits from using peripheral blood as a source for effector cells since it will not conflict with the use of spleen for histopathological investigations in repeated dose toxicity studies. Additionally, since only a minimal number of effector cells are required per sample repeated testing of the same animal is enabled.

Inhibition of human natural killer cell activity by cereulide, an emetic toxin from Bacillus cereus

The lipophilic toxin, cereulide, emitted by emetic food poisoning causing strains of Bacillus cereus, is a powerful mitochondria toxin. It is highly lipophilic and rapidly absorbed from the gut into the bloodstream. We tested how this toxin influences natural killer (NK) cells, which are important effectors in defence against infections and malignancy. Cereulide inhibited cytotoxicity and cytokine production of natural killer cells, caused swelling of natural killer cell mitochondria, and eventually induced natural killer cell apoptosis. The suppressive effect on cytotoxicity was fast and toxic concentration low, 20-30 microg/l. As the emesis causing concentration of cereulide is around 10 microg/kg of total body mass, our results suggest that emesis causing or even lower doses of cereulide may also have a systemic natural killer cell suppressive effect.

Intratumoural and peripheral blood lymphocyte subsets in patients with metastatic renal cell carcinoma undergoing interleukin-2 based immunotherapy: association to objective response and survival

The aim of the present study was to analyse lymphocyte subsets in consecutive peripheral blood samples and consecutive tumour tissue core needle biopsies performed before and during interleukin-2 based immunotherapy, and to correlate the findings with objective response and survival. Twenty-six patients with metastatic renal cell carcinoma were treated with low dose s.c. interleukin-2, interferon-alpha and histamine. A total of 250 blood samples and 62 core needle biopsies from 23 and 19 of these patients, respectively, were analysed. After 2 weeks of treatment, a significant positive correlation between absolute number of peripheral blood lymphocytes (P=0.028), CD3 (P=0.017), CD57 (P=0.041) and objective response was demonstrated. There was no correlation between any peripheral blood leukocyte subsets and survival. Cytotoxicity of peripheral blood mononuclear cells was not correlated to objective response or survival. Within the tumour tissue at baseline, a significant positive correlation between CD4 (P=0.027), CD8 (P=0.028), CD57 (P=0.007) and objective response was demonstrated. After one month of immunotherapy, a significant positive correlation between intratumoral CD3 (P=0.026), CD8 (P=0.015), CD57 (P=0.009) and objective response was demonstrated. A significant positive correlation between intratumoral baseline CD4 (P=0.047), baseline CD57 (P=0.035), CD3 at one month (P=0.049) and survival was demonstrated. These data provide novel in vivo evidence of the possible contribution of lymphocyte subsets in the tumour reduction in responding patients during interleukin-2 based immunotherapy. Confirmation of the results requires further studies including a larger number of patients.

The "ex vivo" patterns of CD2/CD7, CD57/CD11c, CD38/CD11b, CD45RA/CD45RO, and CD11a/HLA-DR expression identify acute/early and chronic/late NK-cell activation states

To define a dynamic sequence of phenotypic changes related to early and late phases of NK-cell activation, we have analyzed by four-color flow cytometry the immunophenotype of normal blood NK-cells from 12 healthy individuals and compared it with those from 15 patients with acute viral infections and 15 patients with either chronic infections or tumors. Although a great interindividual variability was found, nonstimulated CD56(+) NK-cells, present in normal blood samples, usually were CD2(-/+lo), CD7(+hi), HLA-DR(-), CD11b(+), CD38(+), CD11a(+hi), CD45RA(+hi), and CD45RO(-), the expression of CD11c and CD57 being heterogeneous and variable. Recently activated NK-cells, herein corresponding to NK-cells from patients with acute viral infections, displayed a pattern of expression of CD2/CD7 similar to that referred to above, but they typically showed higher levels of CD11a, CD38, and HLA-DR, as well as downregulation of CD11b and CD45RA, accompanied in some cases by coexpression of CD45RO; in addition, these NK-cells were CD11c(+) and CD57(-/+lo). Late-activated NK-cells, represented by NK-cells present in patients with chronic infections and tumors, converted into a CD2(+hi)/CD7(-/+lo) immunophenotype and expressed heterogeneously low levels of CD38 and CD11b; moreover, they were CD57(+) and CD11c(-/+). At this stage, most NK-cells had already reverted into their original CD45RA(+)/CD45RO(-)/HLA-DR(-) phenotype. In summary, we show that the patterns of expression of CD2/CD7, CD57/CD11c, CD38/CD11b, CD45RA/CD45RO, and CD11a/HLA-DR may help us to define the immunophenotypic profiles associated with early and late NK-cell activation phases in 'in vivo' models.