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Natural Cytotoxicity Receptors (natural + cytotoxicity_receptor)

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Medical Sciences	100%

Selected Abstracts

ORIGINAL ARTICLE: Correlation Between Natural Cytotoxicity Receptors and Intracellular Cytokine Expression of Peripheral Blood NK Cells in Women with Recurrent Pregnancy Losses and Implantation Failures

AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 6 2009
Atsushi Fukui
Problem, Natural cytotoxicity receptors (NCRs) are unique markers, which regulate NK cell cytotoxicity and cytokine production. We investigated whether women with recurrent pregnancy losses (RPLs) and implantation failures have aberrant correlation between NCRs and intracellular cytokine expression of NK cells. Method of study, Peripheral blood NK cells (CD56dim and CD56bright) were analyzed for NCRs (NKp46, NKp44 and NKp30) and cytokine expression (TNF-,, IFN-,, IL-4, IL-10) using flow cytometry in RPL (n = 22), implantation failures (n = 23) or controls (n = 15). Results, In type 1 cytokine studies, CD56bright/NKp30+ cells in controls (r = 0.696, P < 0.05) were positively correlated with CD56bright/IFN-,+/TNF-,+ cells. CD56bright/NKp46+ cells in implantation failures (r = ,0.76, P < 0.01) were negatively correlated with CD56bright/IFN-,+/TNF-,, cells. RPL did not have any correlation. In type 2 cytokine studies, CD56+/NKp46+ cells (r = 0.758, P < 0.01) and CD56+/NKp30+ cells (r = 0.637, P < 0.05) were positively correlated with CD56bright/IL-4+/IL-10+ cells in controls. CD56+/NKp30+ cells in implantation failures (r = ,0.778, P < 0.05) were negatively correlated with CD56bright/IL-10+/IL-4+ cells. There were no correlations in RPL. Conclusion, Recurrent pregnancy losses and implantation failures have lack of, or negative correlation between NCRs and intracellular cytokines expression. This observation suggests that excessive pro-inflammatory cytokine expression in NK cells in RPL and implantation failures may be exerted through the NCRs or interruption of signal transduction processes. [source]

1141154113 Expression of natural cytotoxicity receptors in peripheral blood NK cell subsets of women with recurrent spontaneous abortions (RSA) or implantation failures

AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 6 2006
A Fukui
Problem:, Natural Cytotoxicity Receptors (NCRs) are unique markers of NK cells and regulate NK cell cytotoxicity and cytokine production. a2V-ATPase is expressed in the cell membrane and can regulate the pH of the extracellular environment, which might facilitate NK cell killing or cytokine secretion. In this preliminary study we evaluated the expression of NCRs and a2V-ATPase in peripheral blood NK cells of women with RSA or implantation (IVF-ET) failures. Method of Study:, Peripheral blood was obtained from women with RSA (n = 10), or IVF-ET failures (n = 9). CD56dim and CD56bright NK cells were analyzed for the expression of NCRs (NKp46, NKp44 and NKp30) and a2V-ATPase using flow cytometry. Results:, For women with RSA, there were significant differences in the expression of NKp46 between CD56dim (36.9 ± 30.2) and CD56bright (76.0 ± 27.5) (P < 0.01), of NKp30 between CD56dim (30.9 ± 25.7) and CD56bright (55.8 ± 29.5) (P < 0.01), and of a2V-ATPase between CD56dim (1.0 ± 0.9) and CD56bright (23.2 ± 15.1) (P < 0.01) NK cells. For women with IVF-ET failures, there were significant differences in the expression of NKp46 between CD56dim (39.5 ± 21.5) and CD56bright (78.8 ± 26.0) (P < 0.01), of NKp30 between CD56dim (27.2 ± 17.9) and CD56bright (45.2 ± 29.8) (P < 0.05), and of a2V-ATPase between CD56dim (1.6 ± 1.4) and CD56bright (21.2 ± 16.5) (P < 0.01) NK cells. Conclusions:, The differential expression of NCRs and a2V-ATPase in NK cell subsets of women with RSA and IVF-ET failures may have an effect in cytotoxicity and cytokine production. Additional studies are currently in effect to evaluate these activities. We suggest that the analysis of NCRs and a2V-ATPase expression in peripheral blood NK cell subsets may contribute to a better understanding in the biology of NK cells in women with RSA or IVF-ET failures. [source]

Putting the natural killer cell in its place

IMMUNOLOGY, Issue 1 2006
Geraldine M. O'Connor
Summary Natural killer (NK) cells were originally described as ,null' lymphocytes, but we have increasing evidence of their role in recognizing pathogen, and our knowledge of NK cell receptors continues to expand exponentially. Human NK cells have many receptors for human leucoctye antigen (HLA) class I. These killer immunoglobulin-like receptors (KIRs) and CD94/NKG2 receptors can signal in both positive and negative ways to regulate NK cell functions. The inhibitory receptors are the best characterized, but even in these cases much of their functional biology remains elusive. In this review, some recent advances in terms of the three-immunoglobulin (3Ig)-domain KIRs are discussed. Natural cytotoxicity receptors (NCRs) are among the activatory receptors found on NK cells. While pathogen ligands for these receptors have been described, endogenous ligands remain elusive. NCRs and NKG2D, a receptor for stress-induced antigens, appear to play complementary functional roles in terms of NK cell activation. More recently described on NK cells are the Toll-like receptors. In particular, these receptors of the innate immune system allow NK cells to directly sense pathogen, and their ligation on accessory cells indirectly activates NK cells through cytokine production. It is becoming clear that none of these receptor systems functions in isolation and that it is the sum of the signals (which will reflect the pathogenic situation), in addition to the cytokine milieu, that will direct NK cell activation. The resulting cytotoxicity, cytokine production and direct cell,cell regulatory interactions with other cells of the immune system, for example dendritic cells, ultimately determine the role of the NK cell in the context of an overall immune response. [source]

ORIGINAL ARTICLE: Correlation Between Natural Cytotoxicity Receptors and Intracellular Cytokine Expression of Peripheral Blood NK Cells in Women with Recurrent Pregnancy Losses and Implantation Failures

Genesis of the ILT/LIR/MIR clusters within the human leukocyte receptor complex

IMMUNOLOGICAL REVIEWS, Issue 1 2001
Armin Volz
Summary: The human leukocyte receptor complex (LRC) contains at least 26 genes which belong to the immunoglobulin superfamily. The genes include two clusters of immunoglobulin-like transcript (ILT)/leukocyte immunoglobulin-like receptor (LIR)/monocyte-macrophage inhibitory receptor (MIR) loci, a cluster of killer cell inhibitory receptor (KIR) genes, two leukocyte-associated immunoglobulin-like receptor genes, as well as the Fc receptor for IgA and the natural cytotoxicity receptor 1 loci. It has already been postulated that these genes have evolved by multiple duplications, while the two ILT clusters are likely to have been generated by the inverse duplication of an ancient ILT cluster. To shed more light on the possible origin of the loci within the LRC, we have now investigated the presence of KIR and ILT loci in a variety of vertebrates by hybridizations and compared the genomic sequences of all ILT genes. Our results lead to the following conclusions: 1) the origin of KIR genes dates back to about 100 million years, but only primate and human KIRs are closely related; 2) in contrast, genes which are detectable with human ILT cDNAs are already found in birds, suggesting their presence already about 300 million years ago. Using the sequence data produced by the human genome project, we have developed a hypothesis that reconstructs the genesis of the two human ILT clusters in detail which will help to understand the function of the LRC. This work was supported by the European Union through grant BMH4-CT96,1105 (to A.Z.). We also thank the Sonnenfeld-Stiftung (Berlin) and the Berliner Krebsgesellschaft for financial support. [source]

Increased natural cytotoxicity receptor expression and relevant IL-10 production in NK cells from chronically infected viremic HCV patients

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2007
Andrea De Maria M. D.
Abstract Hepatitis C virus (HCV) readily establishes high-level lifelong persistent infection in the majority of immunocompetent adults with failure of HCV-specific CD8+ CTL to clear viral replication. Virus-induced conditioning of innate immune responses is a possible mechanism that may contribute to the impairment of virus-specific CD8+ CTL responses. Here, we analyzed whether triggering of NK cell receptor expression and function is affected during chronic viremic HCV infection. Flow cytometric analysis of purified resting peripheral NK cells showed no evidence of NK cell activation, while analysis of natural cytotoxicity receptors (NCR) showed that NK cells from HCV-infected patients had selective increased expression of NKp30 and NKp46. NK cells had corresponding conserved cytotoxic activity against all targets with the exception of HepG2 hepatoma cells. Freshly separated NK cells from HCV patients showed significant production of IL-10 and normal concentrations of IFN-, upon cell-mediated triggering. Thus, increased expression of NKp30 during HCV infection with increased IL-10 production could contribute, once NK cells localize in the liver, to a NK-DC crosstalk leading to skewing of subsequent adaptive immune responses and lack of virus control. [source]

Selective cross-talk among natural cytotoxicity receptors in human natural killer cells

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2003
Raffaella Augugliaro
Abstract The cytolytic activity of human natural killer cells is induced by several triggering cell surface receptors upon interaction with specific cellular ligands. These receptors include NKp46, NKp30 and NKp44, collectively termed natural cytotoxicity receptors (NCR). Co-operation among NCR has been shown to occur for optimal recognition and killing of most tumor target cells. In this study, we show that the mAb-mediated engagement and clustering of one or another NCR results in the activation of an identical set of tyrosine kinases. These kinases are included in the signaling cascade leading to tyrosine phosphorylation of different receptor-associated signal transducing molecules i.e. CD3, (associated with NKp46 and NKp30) and KARAP/DAP12 (associated with NKp44). In line with the notion that the engagement of inhibitory receptors prevents NCR-mediated responses, we show that the engagement of CD94/NKG2A virtually abrogates the tyrosine phosphorylation of the NCR-associated signaling molecules, i.e. it acts at the very early steps of the signaling cascade. Importantly, the engagement of a single NCR resulted in the activation of the signaling cascades associated with the other NCR. This "cross-talk" is confined to NKp46, NKp30 and NKp44 since neither CD16-nor KIR2DS4-associated signaling polypeptides were phosphorylated following the NCR engagement. These results suggest that a functional cross-talk specifically occurs among different NCR, possibly resulting in the amplification of the activating signals. [source]

Human natural killer cell receptors and co-receptors

IMMUNOLOGICAL REVIEWS, Issue 1 2001
Roberto Biassoni
Summary: In the absence of sufficient signaling by their HLA class I-specific inhibitory receptors, human natural killer (NK) cells become activated and display potent cytotoxicity against cells that are either HLA class I negative or deficient. This indicates that the NK receptors responsible for the induction of cytotoxicity recognize ligands on target cells different from HLA class I molecules. On this basis, the process of NK-cell triggering can be considered as a mainly non-MHC-restricted mechanism. The recent identification of a group of NK-specific triggering surface molecules has allowed a first series of pioneering studies on the functional/molecular characteristics of such receptors. The first three members of a receptor family that has been termed natural cytotoxicity receptors (NCR) are represented by NKp46, NKp44 and NKp30. These receptors are strictly confined to NK cells, and their engagement induces a strong activation of NK-mediated cytolysis. A direct correlation exists between the surface density of NCR and the ability of NK cells to kill various target cells. Importantly, mAb-mediated blocking of these receptors has been shown to suppress cytotoxicity against most NK-susceptible target cells. However, the process of NK-cell triggering during target cell lysis may also depend on the concerted action of NCR and other triggering receptors, such as NKG2D, or surface molecules, including 2B4 and NKp80, that appear to function as co-receptors rather than as true receptors. Notably, a dysfunction of 2B4 has been associated with a severe form of immunodeficiency termed X-linked lymphoproliferative disease. Future studies will clarify whether also the altered expression and/or function of other NK-triggering molecules may represent a possible cause of immunological disorders. This work was supported by grants awarded by Associazione Italiana per la Ricerca sul Cancro (A.I.R.C.), Istituto Superiore di Sanità (I.S.S.), Ministero della Sanità, and Ministero dell'Università e della Ricerca Scientifica e Tecnologica (M.U.R.S.T.) and Consiglio Nazionale delle Ricerche, Progetto Finalizzato Biotecnologie. The financial support of Telethon-Italy (grant no. E.0892) is gratefully acknowledged. [source]

1141154113 Expression of natural cytotoxicity receptors in peripheral blood NK cell subsets of women with recurrent spontaneous abortions (RSA) or implantation failures

2B4 expression on natural killer cells increases in HIV-1 infected patients followed prospectively during highly active antiretroviral therapy

CLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2005
S. R. Ostrowski
Summary Human immunodeficiency virus (HIV)-1 infection influences natural killer (NK) cell expression of inhibitory NK receptors and activating natural cytotoxicity receptors. It is unknown whether expression of the co-stimulatory NK cell receptor 2B4 (CD244) on NK cells and CD3+ CD8+ cells are affected by highly active antiretroviral therapy (HAART), low-level viraemia, proviral-DNA or immune activation in HIV-1 infected patients. A total of 101 HAART-treated HIV-1 infected patients with ,,200 HIV-RNA copies/ml were followed prospectively for 24 months. HIV-RNA was investigated 3-monthly and 2B4 expression on CD3, CD16+ NK cells and CD3+ CD8+ cells, proviral-DNA and plasma soluble tumour necrosis factor receptor (sTNFr)-II were investigated 6-monthly. For comparison, 2B4 expression was investigated in 20 healthy individuals. The concentration of 2B4+ NK cells was initially reduced in HIV-1 infected patients (P < 0·001) but increased to a normal level during the 24 months' follow-up. The concentration of CD3+ CD8+ 2B4+ cells in HIV-1 infected patients was normal and did not change during follow-up. The relative fluorescence intensity (RFI) of 2B4 increased on both NK cells and CD3+ CD8+ cells during follow-up (both P < 0·001). Higher levels of proviral-DNA carrying cells and plasma sTNFrII were associated with reductions in the concentration of 2B4+ NK cells (all P < 0·05). HIV-RNA had no effect on 2B4 expression on NK cells or CD3+ CD8+ cells. These findings demonstrate that the concentration of 2B4+ NK cells normalizes during long-term HAART in HIV-1 infected patients. The finding that proviral-DNA and sTNFrII were associated negatively with the concentration of 2B4+ NK cells suggests that immune activation in HIV-1 infected patients receiving HAART influences the target cell recognition by NK cells. [source]