• Autoimmunity
• Innate Lymphoid Cells (ILC)
• NKp46
• Natural Cytotoxicity Receptors (NCR)
• Natural killer cells
• Tumor immunology

• Humans
• Natural Cytotoxicity Triggering Receptor 1/metabolism
• Killer Cells, Natural/immunology
• Animals
• Neoplasms/immunology
• Neoplasms/therapy
• Neoplasms/etiology
• Immune System Diseases/immunology
• Immune System Diseases/etiology
• Disease Susceptibility

• 82073099 National Natural Science Foundation of China
• 2024JJ5462 Natural Science Foundation of Hunan Province

• CTCL
• TCR sequencing
• gene signature
• heterogeneity
• malignant T cells
• single-cell RNA sequencing

• Universität Duisburg-Essen

• TNBC
• breast cancer
• gamma delta T cell
• immunotherapy
• γδT cell

• Humans
• Triple Negative Breast Neoplasms/immunology
• Triple Negative Breast Neoplasms/therapy
• Animals
• Female
• Receptors, Antigen, T-Cell, gamma-delta/immunology
• Receptors, Antigen, T-Cell, gamma-delta/metabolism
• Intraepithelial Lymphocytes/immunology
• Intraepithelial Lymphocytes/metabolism
• Immunotherapy, Adoptive/methods
• Immunotherapy/methods

The activating receptor NKp46 shows a unique expression pattern on porcine leukocytes. We showed already that in swine not all NK cells express NKp46 and that CD3⁺NKp46⁺ lymphocytes form a T-cell subset with unique functional properties. Here we demonstrate the expression of NKp46 on CD4^highCD14^-CD172a⁺ porcine plasmacytoid dendritic cells (pDCs). Multicolor flow cytometry analyses revealed that the vast majority of porcine pDCs (94.2% ± 4) express NKp46 ex vivo and have an increased expression on the single-cell level compared to NK cells. FSC/SSC^highCD4^highNKp46⁺ cells produced high levels of IFN-α after CpG ODN 2216 stimulation, a hallmark of pDC function. Following receptor triggering with plate-bound monoclonal antibodies against NKp46, phosphorylation of signaling molecules downstream of NKp46 was analyzed in pDCs and NK cells. Comparable to NK cells, NKp46 triggering led to an upregulation of the phosphorylated ribosomal protein S6 (pS6) in pDCs, indicating an active signaling pathway of NKp46 in porcine pDCs. Nevertheless, a defined effector function of the NK-associated receptor on porcine pDCs could not be demonstrated yet. NKp46-mediated cytotoxicity, as shown for NK cells, does not seem to occur, as NKp46⁺ pDCs did not express perforin. Yet, NKp46 triggering seems to contribute to cytokine production in porcine pDCs, as induction of TNF-α was observed in a small pDC subset after NKp46 cross-linking. To our knowledge, this is the first report on NKp46 expression on pDCs in a mammalian species, showing that this receptor contributes to pDC activation and function.

• Animals
• Dendritic Cells
• Interferon-alpha
• Killer Cells, Natural
• Mammals/metabolism
• Natural Cytotoxicity Triggering Receptor 1/metabolism
• Perforin/metabolism
• Swine

Natural killer (NK) cells are part of the innate immunity repertoire, and function in the recognition and destruction of tumorigenic and pathogen-infected cells. Engagement of NK cell activating receptors can lead to functional activation of NK cells, resulting in lysis of target cells. NK cell activating receptors specific for non-major histocompatibility complex ligands are NKp46, NKp44, NKp30, NKG2D, and CD16 (also known as FcγRIII). The natural cytotoxicity receptors (NCRs), NKp46, NKp44, and NKp30, have been implicated in functional activation of NK cells following influenza virus infection via binding with influenza virus hemagglutinin (HA). In this review we describe NK cell and influenza A virus biology, and the interactions of influenza A virus HA and other pathogen lectins with NK cell natural cytotoxicity receptors (NCRs). We review concepts which intersect viral immunology, traditional virology and glycobiology to provide insights into the interactions between influenza virus HA and the NCRs. Furthermore, we provide expert opinion on future directions that would provide insights into currently unanswered questions.

• NKp30
• NKp44
• NKp46
• hemagglutinin
• influenza
• natural cytotoxicity receptors
• natural killer cells

• Toll-like receptors
• activating NK receptors
• human natural killer cells
• innate immunity
• natural cytotoxicity receptors

• Adaptive Immunity/immunology
• Cell Communication/immunology
• Cytotoxicity, Immunologic/immunology
• Humans
• Immunity, Innate/immunology
• Immunologic Memory/immunology
• Killer Cells, Natural/immunology
• Lymphocytes/immunology
• Neoplasms/immunology
• Receptors, Natural Killer Cell/immunology

The Natural Cytotoxicity Receptors (NCRs), NKp46, NKp44, and NKp30, were some of the first human activating Natural Killer (NK) cell receptors involved in the non-MHC-restricted recognition of tumor cells to be cloned over 20 years ago. Since this time many host- and pathogen-encoded ligands have been proposed to bind the NCRs and regulate the cytotoxic and cytokine-secreting functions of tissue NK cells. This diverse set of NCR ligands can manifest on the surface of tumor or virus-infected cells or can be secreted extracellularly, suggesting a remarkable NCR polyfunctionality that regulates the activity of NK cells in different tissue compartments during steady state or inflammation. Moreover, the NCRs can also be expressed by other innate and adaptive immune cell subsets under certain tissue conditions potentially conferring NK recognition programs to these cells. Here we review NCR biology in health and disease with particular reference to how this important class of receptors regulates the functions of tissue NK cells as well as confer NK cell recognition patterns to other innate and adaptive lymphocyte subsets. Finally, we highlight how NCR biology is being harnessed for novel therapeutic interventions particularly for enhanced tumor surveillance.

• disease association
• immunoregulation
• natural killer cell
• receptors
• tissue homeostasis

• NK cells
• NKp46
• antibody
• cancer
• type 1 diabetes

• DLBCL
• Immunomodulation
• NK activation
• NKp44

KIR3DL2 is a member of the killer cell immunoglobulin-like receptor (KIR) family that was initially identified at the surface of natural killer (NK) cells. KIR3DL2, also known as CD158k, is expressed as a disulfide-linked homodimer. Each chain is composed of three immunoglobulin-like domains and a long cytoplasmic tail containing two immunoreceptor tyrosine-based inhibitory motifs. Beside its expression on NK cells, it is also found on rare circulating T lymphocytes, mainly CD8⁺. Although the KIR gene number varies between haplotype, KIR3DL2 is a framework gene present in all individuals. Together with the presence of genomic regulatory sequences unique to KIR3DL2, this suggests some particular functions for the derived protein in comparison with other KIR family members. Several ligands have been identified for KIR3DL2. As for other KIRs, binding to HLA class I molecules is essential for NK development by promoting phenomena such as licensing and driving NK cell maturation. For KIR3DL2, this includes binding to HLA-A3 and -A11 and to the free heavy chain form of HLA-B27. In addition, KIR3DL2 binds to CpG oligonucleotides (ODN) and ensures their transport to endosomal toll-like receptor 9 that promotes cell activation. These characteristics have implicated KIR3DL2 in several pathologies: ankylosing spondylitis and cutaneous T-cell lymphomas such as Sézary syndrome, CD30⁺ cutaneous lymphoma, and transformed mycosis fungoides. Consequently, a new generation of humanized monoclonal antibodies (mAbs) directed against KIR3DL2 has been helpful in the diagnosis, follow-up, and treatment of these diseases. In addition, preliminary clinical studies of a novel targeted immunotherapy for cutaneous T-cell lymphomas using the anti-KIR3DL2 mAb IPH4102 are now underway. In this review, we discuss the various aspects of KIR3DL2 on the functions of CD4⁺ T cells and how targeting this receptor helps to develop innovative therapeutic strategies.

• KIR3DL2
• Sézary syndrome
• cutaneous T-cell lymphomas
• monoclonal antibody
• mycosis fungoides
• tumor marker

• cell surface marker
• cutaneous T-cell lymphoma
• gene expression
• screening
• secretory protein

• Biomarkers/blood
• Gene Expression
• Humans
• Mycosis Fungoides/blood
• Mycosis Fungoides/diagnosis
• Sezary Syndrome/blood
• Sezary Syndrome/diagnosis

• P50 CA121973 NCI NIH HHS

• CD164
• FCRL3
• KIR3DL2
• Sézary syndrome
• Tox
• miR-214

• Biomarkers, Tumor/analysis
• Biomarkers, Tumor/genetics
• CD4-Positive T-Lymphocytes/chemistry
• CD4-Positive T-Lymphocytes/immunology
• Case-Control Studies
• Endolyn/analysis
• Endolyn/genetics
• Flow Cytometry
• Gene Expression Profiling/methods
• Gene Expression Regulation, Neoplastic
• High Mobility Group Proteins/analysis
• High Mobility Group Proteins/genetics
• Humans
• Lymphocytes, Tumor-Infiltrating/chemistry
• Lymphocytes, Tumor-Infiltrating/immunology
• MicroRNAs/genetics
• RNA, Messenger/genetics
• RNA, Messenger/metabolism
• Real-Time Polymerase Chain Reaction
• Receptors, Immunologic/analysis
• Receptors, Immunologic/genetics
• Reverse Transcriptase Polymerase Chain Reaction
• Sezary Syndrome/diagnosis
• Sezary Syndrome/genetics
• Sezary Syndrome/immunology
• Sezary Syndrome/metabolism
• Skin Neoplasms/diagnosis
• Skin Neoplasms/genetics
• Skin Neoplasms/immunology
• Skin Neoplasms/metabolism

• K08 AR065577 NIAMS NIH HHS
• K23 AR068433 NIAMS NIH HHS
• R01 CA203721 NCI NIH HHS
• R21 CA178424 NCI NIH HHS

The CD3⁻NKp46⁺ phenotype is frequently used for the identification of natural killer (NK) cells in various mammalian species. Recently, NKp46 expression was analyzed in more detail in swine. It could be shown that besides CD3⁻NKp46⁺ lymphocytes, a small but distinct population of CD3⁺NKp46⁺ cells exists. In this study, we report low frequencies of CD3⁺NKp46⁺ lymphocytes in blood, lymph nodes, and spleen, but increased frequencies in non-lymphatic organs, like liver and lung. Phenotypic analyses showed that the majority of CD3⁺NKp46⁺ cells coexpressed the CD8αβ heterodimer, while a minor subset expressed the TCR-γδ, which was associated with a CD8αα⁺ phenotype. Despite these T-cell associated receptors, the majority of CD3⁺NKp46⁺ lymphocytes displayed a NK-related phenotype (CD2⁺CD5⁻CD6⁻CD16⁺perforin⁺) and expressed mRNA of NKp30, NKp44, and NKG2D at similar levels as NK cells. Functional tests showed that CD3⁺NKp46⁺ lymphocytes produced IFN-γ and proliferated upon cytokine stimulation to a similar extent as NK cells, but did not respond to the T-cell mitogen, ConA. Likewise, CD3⁺NKp46⁺ cells killed K562 cells with an efficiency comparable to NK cells. Cross-linking of NKp46 and CD3 led to degranulation of CD3⁺NKp46⁺ cells, indicating functional signaling pathways for both receptors. Additionally, influenza A(H1N1)pdm09-infected pigs had reduced frequencies of CD3⁺NKp46⁺ lymphocytes in blood, but increased frequencies in the lung in the early phase of infection. Thus, CD3⁺NKp46⁺ cells appear to be involved in the early phase of influenza infections. In summary, we describe a lymphocyte population in swine with a mixed phenotype of NK and T cells, with results so far indicating that this cell population functionally resembles NK cells.

• CD3
• NK cells
• NKp46
• influenza
• swine

• NKp46
• chymase
• granzyme B
• mast cell
• tryptase

• Adolescent
• Adult
• Aged
• Cell Line, Tumor
• Child
• Child, Preschool
• Chymases/metabolism
• Female
• Gene Knockdown Techniques
• Granzymes/biosynthesis
• Humans
• Infant
• Infant, Newborn
• Interleukins/biosynthesis
• Male
• Mast Cells/metabolism
• Middle Aged
• Natural Cytotoxicity Triggering Receptor 1/genetics
• Natural Cytotoxicity Triggering Receptor 1/metabolism
• Phenotype
• Serine Proteases/biosynthesis
• Tryptases/metabolism
• Urticaria Pigmentosa/enzymology
• Urticaria Pigmentosa/metabolism
• Young Adult
• Interleukin-22

• Animals
• Antibodies, Monoclonal, Humanized/administration & dosage
• Antibody-Dependent Cell Cytotoxicity/immunology
• Cell Line, Tumor
• Humans
• Lymphoma, T-Cell, Cutaneous/drug therapy
• Lymphoma, T-Cell, Cutaneous/immunology
• Lymphoma, T-Cell, Cutaneous/pathology
• Mice
• Neoplasm Staging
• Receptors, KIR3DL2/biosynthesis
• Receptors, KIR3DL2/immunology

• CD26
• CTCL
• Flow cytometry
• Hypermethylation
• Immunophenotypic changes
• Sézary syndrome

• CD335
• Large granular lymphocyte
• Leukemia
• Lymphoma
• NKp46
• Natural killer
• T cell

Sézary syndrome (SS) is an aggressive variant of cutaneous T cell lymphoma characterized by the presence of malignant T cells in the skin, peripheral blood and lymph nodes. The tumoral population typically displays a CD3⁺ CD4⁺ CD45RO⁺ memory T cell phenotype. We report a case of SS with an aberrant CD56⁺ immunophenotype. This patient presented with a generalized erythroderma and palpable small axillary lymph nodes. SS (stage IVA) was diagnosed on histological criteria and by the detection of a major T cell clone in skin and blood, an elevated CD4/CD8 T cell ratio and Sézary cells count > 1000/mm³. Beside the Sézary cell marker KIR3DL2, immunostainings revealed that two third of the malignant cells expressed CD56 but no other natural killer (NK) cell marker such as CD16, CD160 or NKp46. This atypical expression was not linked to an activation-dependent process and remained stable during the time course of the disease. No loss of the pan T-cell markers CD2, CD3 or CD4 was detected while a complete down-modulation of CD26 was observed. Despite several lines of treatment, no durable amelioration was observed and patient died after 10 mo of follow-up. Because this CD4⁺ CD56⁺ SS case is the only one reported so far, the functional significance of CD56 expression remained difficult to assess in terms of aggressiveness and prognosis.

• Cutaneous T cell lymphomas
• Sézary syndrome
• CD56

Digestive malignancies, especially pancreatic cancer (PC), gastric cancer (GC), and colorectal cancer (CRC), still occur at persistently high rates, and disease progression in these cancers has been associated with tumor immunosurveillance escape. Natural killer (NK) cell dysfunction may be responsible for this phenomenon, however, the exact relationship between tumor immunosurveillance escape in digestive malignancies and NK cell dysfunction remains unclear.

Percentage of the surface receptors NKG2A, KIR3DL1, NKG2D, NKp30, NKp44, NKp46, and DNAM-1, as well as the cytotoxic granules perforin and granzyme B positive NK cells were determined in patients with pancreatic cancer (n = 31), gastric cancer (n = 31), and CRC (n = 32) prior to surgery and healthy controls (n = 31) by multicolor flow cytometry. Independent t-tests or Mann-Whitney U-tests were used to compare the differences between the patient and healthy control groups, as well as the differences between patients with different pathologic features of cancer.

Percentage of NKG2D, NKp30, NKp46, and perforin positive NK cells was significantly down-regulated in patients with PC compared to healthy controls, as well as GC and CRC; reduced levels of these molecules was associated with indicators of disease progression in each malignancy (such as histological grade, depth of invasion, lymph node metastasis). On the contrary, percentage of KIR3DL1 positive NK cells was significantly increased in patients with PC, as well as GC and CRC, but was not associated with any indicators of disease progression.

Altered percentage of surface receptors and cytotoxic granules positive NK cells may play a vital role in tumor immunosurveillance escape by inducing NK cell dysfunction in patients with PC, GC, and CRC.

Sézary syndrome (SS) cells express cell surface molecules also found on normal activated CD4 T cells. In an effort to find a more specific surface marker for malignant SS cells, a microarray analysis of gene expression was performed. Results showed significantly increased levels of mRNA for CD164, a sialomucin found on human CD34+ hematopoietic stem cells, and FCRL3, a molecule present on a subset of human natural T regulatory cells. Both markers were increased in CD4 T cells from SS patients compared to healthy donors. Flow cytometry studies confirmed the increased expression of CD164 and FCRL3 primarily on CD4+CD26− T cells of SS patients. Importantly, a statistically significant correlation was found between an elevated percentage of CD4+CD164+ T cells and an elevated percentage of CD4+CD26− T cells in all tested SS patients but not in patients with Mycosis Fungoides and atopic dermatitis or healthy donors. FCRL3 expression was significantly increased only in high tumor burden patients. CD4+CD164+ cells displayed cerebriform morphology and their loss correlated with clinical improvement in treated patients. Our results suggest that CD164 can serve as a marker for diagnosis and for monitoring progression of CTCL/SS and that FCRL3 expression correlates with a high circulating tumor burden.

To better understand the pathogenesis of Sézary cells, distinguish them from reactive skin-infiltrating T-cells and improve disease treatment, efforts have been made to identify molecular targets deregulated by the malignant process. From immunophenotypic analysis and subtractive differential expression experiments to pan-genomic studies, many approaches have been used to identify markers of the disease. During the last decade several natural killer (NK) cell markers have been found aberrantly expressed at the surface of Sézary cells. In particular, KIR3DL2/CD158k, expressed by less than 2% of healthy individuals CD4⁺ T-cells, is an excellent marker to identify and follow the tumor burden in the blood of Sézary syndrome patients. It may also represent a valuable target for specific immunotherapy. Other products of the NK cluster on chromosome 19q13 have been detected on Sézary cells, raising the hypothesis of an NK reprogramming process associated with the malignant transformation that may induce survival functions.

• Sézary syndrome
• Mycosis fungoides
• Natural killer receptors
• KIR3DL2
• Cutaneous T-cell lymphomas

• NCRs
• T cells
• activation
• homeostasis
• mucosal immunity

Pathogenic or regulatory effects of natural killer (NK) cells are implicated in many autoimmune diseases, but evidence in multiple sclerosis (MS) and its murine models remains equivocal. In an effort to illuminate this, we have here analysed expression of the prototypic NK cell marker, NCR1 (natural cytotoxicity triggering receptor; NKp46; CD335), an activating receptor expressed by virtually all NK cells and therefore considered a pan-marker for NK cells. The only definitive ligand of NCR1 is influenza haemagglutinin, though there are believed to be others. In this study, we investigated whether there were differences in NCR1⁺ cells in the peripheral blood of MS patients and whether NCR1⁺ cells are present in white matter lesions.

We first investigated the expression of NCR1 on peripheral blood mononuclear cells and found no significant difference between healthy controls and MS patients. We then investigated mRNA levels in central nervous system (CNS) tissue from MS patients: NCR1 transcripts were increased more than 5 times in active disease lesions. However when we performed immunohistochemical staining of this tissue, few NCR1⁺ NK cells were identified. Rather, the major part of NCR1 expression was localised to astrocytes, and was considerably more pronounced in MS patients than controls. In order to further validate de novo expression of NCR1 in astrocytes, we used an in vitro staining of the human astrocytoma U251 cell line grown to model whether cell stress could be associated with expression of NCR1. We found up-regulation of NCR1 expression in U251 cells at both the mRNA and protein levels.

The data presented here show very limited expression of NCR1⁺ NK cells in MS lesions, the majority of NCR1 expression being accounted for by expression on astrocytes. This is compatible with a role of this cell-type and NCR1 ligand/receptor interactions in the innate immune response in the CNS in MS patients. This is the first report of NCR1 expression on astrocytes in MS tissue: it will now be important to unravel the nature of cellular interactions and signalling mediated through innate receptor expression on astrocytes.