Regulating the immune system via IL-15 transpresentation

Transpresentation has emerged as an important mechanism mediating IL-15 responses in a subset of lymphocytes during the steady state. In transpresentation, cell surface IL-15, bound to IL-15Rα is delivered to opposing lymphocytes during a cell-cell interaction. The events most dependent on IL-15 include the development and homeostasis of memory CD8 T cells, Natural Killer cells, invariant Natural Killer T cells, and intraepithelial lymphocytes. As lymphocyte development and homeostasis involve multiple steps and mechanisms, IL-15 transpresentation can have diverse roles throughout. Moreover, distinct stages of lymphocyte differentiation require IL-15 transpresented by different cells, which include both hematopoietic and non-hematopoietic cell types. Herein, we will describe the points where IL-15 transpresentation impacts these processes, the specific cells thought to drive IL-15 responses, as well as their role in the course of development and homeostasis.     

Selective expansion and partial activation of human NK cells and NK receptor-positive T cells by IL-2 and IL-15.

IL-2 and IL-15 are lymphocyte growth factors produced by different cell types with overlapping functions in immune responses. Both cytokines costimulate lymphocyte proliferation and activation, while IL-15 additionally promotes the development and survival of NK cells, NKT cells, and intraepithelial lymphocytes. We have investigated the effects of IL-2 and IL-15 on proliferation, cytotoxicity, and cytokine secretion by human PBMC subpopulations in vitro. Both cytokines selectively induced the proliferation of NK cells and CD56(+) T cells, but not CD56(-) lymphocytes. All NK and CD56(+) T cell subpopulations tested (CD4(+), CD8(+), CD4(-)CD8(-), alphabetaTCR(+), gammadeltaTCR(+), CD16(+), CD161(+), CD158a(+), CD158b(+), KIR3DL1(+), and CD94(+)) expanded in response to both cytokines, whereas all CD56(-) cell subpopulations did not. Therefore, previously reported IL-15-induced gammadelta and CD8(+) T cell expansions reflect proliferations of NK and CD56(+) T cells that most frequently express these phenotypes. IL-15 also expanded CD8alpha(+)beta(-) and Valpha24Vbeta11 TCR(+) T cells. Both cytokines stimulated cytotoxicity by NK and CD56(+) T cells against K562 targets, but not the production of IFN-gamma, TNF-alpha, IL-2, or IL-4. However, they augmented cytokine production in response to phorbol ester stimulation or CD3 cross-linking by inducing the proliferation of NK cells and CD56(+) T cells that produce these cytokines at greater frequencies than other T cells. These results indicate that IL-2 and IL-15 act at different stages of the immune response by expanding and partially activating NK receptor-positive lymphocytes, but, on their own, do not influence the Th1/Th2 balance of adaptive immune responses.     

The human liver contains multiple populations of NK cells, T cells, and CD3+CD56+ natural T cells with distinct cytotoxic activities and Th1, Th2, and Th0 cytokine secretion patterns.

The human liver contains significant numbers of T cells, NK cells, and lymphocytes that coexpress T and NK cell receptors. To evaluate their functional activities, we have compared the cytotoxic activities and cytokines produced by normal adult hepatic CD3+CD56- (T) cells, CD3-CD56+ (NK) cells, and CD3+CD56+ (natural T (NT)) cells. In cytotoxicity assays using immunomagnetic bead-purified NK cell, T cell, and NT cell subpopulations as effectors, fresh hepatic NK cells lysed K562 targets, while NT cells could be induced to do so by culturing with IL-2. Both NT and T cells were capable of redirected cytolysis of P815 cells using Abs to CD3. Flow cytometric analysis of cytokine production by fresh hepatic lymphocyte subsets activated by CD3 cross-linking or PMA and ionomycin stimulation indicated that NT cells and T cells could produce IFN-gamma, TNF-alpha, IL-2, and/or IL-4, but little or no IL-5, while NK cells produced IFN-gamma and/or TNF-alpha only. The majority of NT cells produced inflammatory (Th1) cytokines only; however, approximately 6% of all hepatic T cells, which included 5% of Valpha24 TCR-bearing NT cells and 2% of gammadeltaTCR+ cells, simultaneously produced IFN-gamma and IL-4. The existence of such large numbers of cytotoxic lymphocytes with multiple effector functions suggests that the liver is an important site of innate immune responses, early regulation of adaptive immunity, and possibly peripheral deletion of autologous cells.     

Antigenic, functional, and molecular genetic studies of human natural killer cells and cytotoxic T lymphocytes not restricted by the major histocompatibility complex

Cytotoxicity not restricted by the major histocompatibility complex (MHC) is mediated by two distinct types of lymphocyte: natural killer (NK) cells and non-MHC-restricted cytotoxic T lymphocytes (CTL). These two types of cytotoxic lymphocytes can be distinguished by antigenic phenotype, function, and molecular genetic studies. In human peripheral blood, NK cells are identified by expression of the Leu-19 and/or CD16 cell surface antigens, and lack of CD3/T cell antigen receptor (Ti) complex expression (i.e., CD3-,Leu-19+). Peripheral blood non-MHC-restricted CTL express both CD3 and Leu-19 (i.e., CD3+, Leu-19+, referred to as Leu-19+ T cells). Both Leu-19+ T cells and NK cells lyse "NK-sensitive" hematopoietic tumor cell targets, such as K562, without deliberate immunization of the host. However, most "NK activity" in peripheral blood is mediated by NK cells, because they are usually more abundant and more efficient cytotoxic effectors than Leu-19+ T cells. The cytolytic activity of both NK cells and Leu-19+ T cells against hematopoietic targets was enhanced by recombinant interleukin 2 (rIL 2). NK cells, but not peripheral blood Leu-19+ T cells, were also capable of lysing solid tumor cell targets after short-term culture in rIL 2. Southern blot analysis of NK cells revealed that both the T cell antigen receptor beta-chain genes and the T cell-associated gamma genes were not rearranged, but were in germ-line configuration. These findings indicate that NK cells are distinct in lineage from T lymphocytes and do not use the T cell antigen receptor genes for target recognition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Physiologic modulation of natural killer cell activity as an index of Alzheimer's disease progression

Patients with Alzheimer's disease (AD) are characterized by an altered sensitivity to cortisol-mediated modulation of circulating lymphocytes. Longitudinal studies are needed to address the clinical applicability of these abnormalities as prognostic factors. Therefore, we designed a longitudinal study to address the clinical applicability of physiologic modulation of Natural Killer (NK) cell activity as a prognostic factor in AD. NK activity was assessed as baseline measurement and in response to modulation by cortisol at 10(-6)M. To verify the immunophysiological integrity of the NK cell population, we tested augmentation of NK cytotoxicity by human recombinant interleukin (IL)-2 (100 IU/ml) as control. The response to modulation by cortisol or by IL-2 was significantly greater in patients with AD. Based on change in the Mini-Mental State score at entry and at 18 months, patients with AD could be assigned to a "fast progression" (Delta > 2 points) or to a "slow progression" group (Delta 相似文献   

NKT 细胞在动脉粥样硬化中的作用*

然杀伤T细胞(natural killer T cell,NKT细胞)是一种特殊的淋巴细胞亚群,具有部分T细胞和NK细胞的特征。与这些细胞不同的是,NKT细胞不仅能够识别醣脂类抗原,还在激活后产生促炎症因子和抗炎症因子。由于这些特性,NKT细胞在炎症和免疫方面的研究越来越热。动脉粥样硬化是一种受免疫调节的炎性疾病,因此对NKT细胞在该疾病中作用的研究也逐渐开展起来。     

IL-4 confers NK stimulatory capacity to murine dendritic cells: a signaling pathway involving KARAP/DAP12-triggering receptor expressed on myeloid cell 2 molecules

Dendritic cells (DC) regulate NK cell functions, but the signals required for the DC-mediated NK cell activation, i.e., DC-activated NK cell (DAK) activity, remain poorly understood. Upon acute inflammation mimicked by LPS or TNF-alpha, DC undergo a maturation process allowing T and NK cell activation in vitro. Chronic inflammation is controlled in part by Th2 cytokines. In this study, we show that IL-4 selectively confers to DC NK but not T cell stimulatory capacity. IL-4 is mandatory for mouse bone marrow-derived DC grown in GM-CSF (DC(GM/IL-4)) to promote NK cell activation in the draining lymph nodes. IL-4-mediated DAK activity depends on the KARAP/DAP12-triggering receptor expressed on myeloid cell 2 signaling pathway because: 1) gene targeting of the adaptor molecule KARAP/DAP12, a transmembrane polypeptide with an intracytoplasmic immunoreceptor tyrosine-based activation motif, suppresses the DC(GM/IL-4) capacity to activate NK cells, and 2) IL-4-mediated DAK activity is significantly blocked by soluble triggering receptor expressed on myeloid cell 2 Fc molecules. These data outline a novel role for Th2 cytokines in the regulation of innate immune responses through triggering receptors expressed on myeloid cells.     

Interleukin-4. A regulatory protein

Since its discovery in 1982, numerous biological activities of interleukin-4 (IL-4) have been described. Like other cytokines, IL-4 is highly pleiotropic, both with respect to the number of different target cells that are responsive to it and with respect to the number of different biological responses it elicits. Interleukin-4 was initially described as a costimulant for the proliferation of B lymphocytes stimulated with anti-IgM antibody. Synonyms for this cytokine are B cell growth factor-1 (BCGF-1) and B cell stimulatory factor-1 (BSF-1). After cloning of both the murine and human IL-4, the use of recombinant IL-4 enabled detailed studies of its biological functions. Many cell types, mainly of hematological origin, express receptors for IL-4. Accordingly, effects of IL-4 have been described on B lymphocytes, T lymphocytes, NK cells, mononuclear phagocytes, mast cells, fibroblasts and hematopoietic progenitor cells. Currently, there are three major areas in which IL-4 appears to play an important role: 1) regulation of B cell growth and of antibody isotype expression. In this context, a possible role for IL-4 in allergic reactions is of special interest. 2) Stimulation of T cell growth and the generation of cytotoxic T lymphocytes. In addition to the suppressive effects on the induction of non HLA-restricted cellular cytotoxicity by natural killer- (NK) and lymphokine-activated killer (LAK) cells, this suggests a role for IL-4 in the regulation of cellular immune responses. 3) Regulation of the growth and differentiation of hematopoietic bone marrow stem cells. IL-4 itself does not induce proliferation of hematological progenitor cells but it can modulate the growth-factor dependent proliferation of these cells. In this review the biological functions of IL-4, reported until present, are discussed.     

Natural killer and natural killer T cells in liver fibrosis

The liver lymphocyte population is enriched with natural killer (NK) cells, which play a key role in host defense against viral infection and tumor transformation. Recent evidence from animal models suggests that NK cells also play an important role in inhibiting liver fibrosis by selectively killing early or senescence activated hepatic stellate cells (HSCs) and by producing the anti-fibrotic cytokine IFN-γ. Furthermore, clinical studies have revealed that human NK cells can kill primary human HSCs and that the ability of NK cells from HCV patients to kill HSCs is enhanced and correlates inversely with the stages of liver fibrosis. IFN-α treatment enhances, while other factors (e.g., alcohol, TGF-β) attenuate, the cytotoxicity of NK cells against HSCs, thereby differentially regulating liver fibrogenesis. In addition, the mouse liver lymphocyte population is also enriched for natural killer T (NKT) cells, whereas human liver lymphocytes have a much lower percentage of NKT cells. Many studies suggest that NKT cells promote liver fibrogenesis by producing pro-fibrotic cytokines such as IL-4, IL-13, hedgehog ligands, and osteopontin; however, NKT cells may also attenuate liver fibrosis under certain conditions by killing HSCs and by producing IFN-γ. Finally, the potential for NK and NKT cells to be used as therapeutic targets for anti-fibrotic therapy is discussed. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.     

Activated intrahepatic antigen-presenting cells inhibit hepatitis B virus replication in the liver of transgenic mice

In this study we evaluated the ability of activated intrahepatic APCs to inhibit hepatitis B virus (HBV) replication in transgenic mice. Intrahepatic APCs were activated by administration of an anti-CD40 agonistic mAb (alphaCD40). We showed that a single i.v. injection of alphaCD40 was sufficient to inhibit HBV replication noncytopathically by a process associated with the recruitment of dendritic cells, macrophages, T cells, and NK cells into the liver and the induction of inflammatory cytokines. The antiviral effect depended on the production of IL-12 and TNF-alpha by activated APCs; however, it was mediated primarily by IFN-gamma produced by NK cells, and possibly T cells, that were activated by IL-12. Collectively, these results suggest that activated APCs can directly produce antiviral cytokines (IL-12, TNF-alpha) and trigger the production of other cytokines (i.e., IFN-gamma) by other cells (e.g., NK cells and T cells) that do not express CD40. These results provide insight into a hitherto unsuspected antiviral function of intrahepatic APCs, and they suggest that therapeutic activation of APCs may represent a new strategy for the treatment of chronic HBV infection.     

Flow cytometric visualisation of cytokine production by CD3-CD56+ NK cells and CD3+CD56+ NK-T cells in whole blood

BACKGROUND: Natural killer (NK) cells produce multiple cytokines with potential immune regulatory roles. We standardised a whole-blood flow cytometry method to visualise intracellular cytokine production by NK cells for the study of NK cell biology and for clinical monitoring. METHODS: With a three-colour fluorescent labelling technique, specific cytokine production by NK or T cells was visualised directly in whole blood in the same sample after stimulation by phorbol 12-myristate 13-acetate (PMA) and ionomycin and by electronically gating on the CD3-ve/CD56+ve NK population or on the CD3+/CD56+ NK-T-cell population. RESULTS: Detectable levels of tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) but not of interleukin-2 (IL-2) or IL-4 were easily observed in NK cells. The visualisation of the cytokine production by NK cells was dependent on the addition of a Golgi transport inhibitor, Brefeldin A. Other known stimuli for NK cells (IL-2 and CD16 monoclonal antibody and incubation with K562, the NK-sensitive cell line) promoted IFN-gamma and TNF-alpha production in NK cells to a lesser extent than did PMA and ionomycin stimulation. CONCLUSIONS: This whole-blood flow cytometric assay appears to be an useful and easy method to examine cytokine production by NK cells and/or by CD3+CD56+ NK-T lymphocytes in patients with relevant diseases.     

Natural killer,natural killer T,helper and cytotoxic T cells in the decidua from recurrent spontaneous abortion with normal and abnormal chromosome karyotypes

Problem

Recurrent spontaneous abortion (RSA) is associated with immune imbalance at the maternal–fetal interface. Decidual immune cells and cytokines expressed at this interface regulate the response of the maternal immune system to the fetus. However, the populations and cytokine expression levels of these lymphocytes in miscarriage with normal and abnormal chromosome karyotypes remain unclear.

Characterization of developmental pathway of natural killer cells from embryonic stem cells in vitro

In vitro differentiation of embryonic stem (ES) cells is often used to study hematopoiesis. However, the differentiation pathway of lymphocytes, in particular natural killer (NK) cells, from ES cells is still unclear. Here, we used a multi-step in vitro ES cell differentiation system to study lymphocyte development from ES cells, and to characterize NK developmental intermediates. We generated embryoid bodies (EBs) from ES cells, isolated CD34(+) EB cells and cultured them on OP9 stroma with a cocktail of cytokines to generate cells we termed ES-derived hematopoietic progenitors (ES-HPs). EB cell subsets, as well as ES-HPs derived from EBs, were tested for NK, T, B and myeloid lineage potentials using lineage specific cultures. ES-HPs derived from CD34(+) EBs differentiated into NK cells when cultured on OP9 stroma with IL-2 and IL-15, and into T cells on Delta-like 1-transduced OP9 (OP9-DL1) with IL-7 and Flt3-L. Among CD34(+) EB cells, NK and T cell potentials were detected in a CD45(-) subset, whereas CD45(+) EB cells had myeloid but not lymphoid potentials. Limiting dilution analysis of ES-HPs generated from CD34(+)CD45(-) EB cells showed that CD45(+)Mac-1(-)Ter119(-) ES-HPs are highly enriched for NK progenitors, but they also have T, B and myeloid potentials. We concluded that CD45(-)CD34(+) EB cells have lymphoid potential, and they differentiate into more mature CD45(+)Lin(-) hematopoietic progenitors that have lymphoid and myeloid potential. NK progenitors among ES-HPs are CD122(-) and they rapidly acquire CD122 as they differentiate along the NK lineage.     

Natural killer (NK) cell stimulatory factor or IL-12 has differential effects on the proliferation of TCR-alpha beta+, TCR-gamma delta+ T lymphocytes, and NK cells.

We have analyzed the effects of NK cell stimulatory factor/IL-12, on proliferation of PBL and their subsets. IL-12 synergizes with lectins and phorbol diesters to induce proliferation of CD4+ and CD8+ peripheral blood T lymphocytes. In the case of phorbol-diester-induced proliferation, the effect of IL-12 is in part mediated by induced IL-2 production, as suggested by the observation that IL-12 enhances IL-2 production in these cultures and that anti-IL-2 antibodies inhibit proliferation. IL-12 synergizes also with anti-CD3 antibodies and with allogeneic stimulation in MLC in inducing T cell proliferation. IL-12 alone is mitogenic for preactivated T and NK lymphoblasts. This mitogenic effect is observed with similar doses of IL-12 on NK lymphoblasts as well as on CD4+ and CD8+ TCR-alpha beta+ and on TCR-gamma delta+ lymphoblasts. On TCR-alpha beta+ T lymphocytes the effect of IL-12 is always additive to that of IL-2 over a wide dose range. The same effect is observed on highly activated, actively proliferating NK cells. However, on NK and TCR-gamma delta+ lymphoblasts reverting to a resting state after stimulation and on a TCR-gamma delta+ acute leukemia-derived T cell line, IL-12 inhibits significantly the proliferation induced by moderate to high doses (10 to 100 U/ml) of IL-2. This inhibitory effect is, at least in part, indirect, and depends on IL-12-induced production of TNF. Neutralizing anti-TNF antibodies, but not anti-IFN-gamma and anti-transforming growth factor antibodies, restore by more than 70% the inhibition of proliferation induced by IL-12 in these cultures. However, TNF alone cannot mimic the inhibitory effect of IL-12 on the IL-2-induced proliferation of NK and TCR-gamma delta+ lymphoblasts, suggesting the involvement of additional mechanisms. The relevance of these findings for the biology of lymphocyte subsets mediating MHC nonrestricted cytotoxicity is discussed.     

Lysis of human T cell leukemia virus infected T and B lymphoid cells by interleukin 2-activated killer cells

The human T cell leukemia (HTLV-1) retrovirus is the etiologic agent for adult T cell leukemia. Interleukin 2 (IL-2) activated killer (AK) cells have been shown to lyse freshly explanted tumor cells in vitro and have been used as a form of adoptive immunotherapy for the treatment of cancer. In this report, the ability of AK cells to lyse HTLV-1-infected targets was examined. Normal lymphocytes, when cultured in recombinant IL-2 for periods of 3 to 7 days, killed infected T and B cell lines. The precursor for these AK cells resided in the CD-16 antigen-positive subset (i.e., natural killer (NK) cells). Resting T cells, NK cells, or unfractionated lymphocytes did not lyse the infected targets. However, when isolated NK cells were incubated for 24 hr in IL-2, suboptimal cytolysis was induced whereas activation of NK cells with a four pulse of IL-2 was insufficient to generate effector cells. The results of performing cold target inhibition studies with Epstein-Barr virus-infected B cell lines and HTLV-1-infected T and B cell lines suggest that there are discrete subsets (i.e., clonotypic) in the AK population that preferentially lyse a given virally infected cell line. Thus to consider AK cells as true polyspecific killer cells may be inaccurate. Alternately AK cells may express a number of different receptors with variable affinities for the Epstein-Barr virus- and HTLV-1-infected cell lines. In addition, it was shown that HTLV-1-infected B cells are relatively resistant to AK cell-mediated lysis. These results clearly indicate that AK cells but not resting NK cells kill HTLV-1-infected cells.     

NKT细胞在动脉粥样硬化中的作用

然杀伤T细胞（natural killer T cell,NKT细胞）是一种特殊的淋巴细胞亚群,具有部分T细胞和NK细胞的特征。与这些细胞不同的是,NKT细胞不仅能够识别醣脂类抗原,还在激活后产生促炎症因子和抗炎症因子。由于这些特性,NKT细胞在炎症和免疫方面的研究越来越热。动脉粥样硬化是一种受免疫调节的炎性疾病,因此对NKT细胞在该疾病中作用的研究也逐渐开展起来。     

Homing and function of human skin gammadelta T cells and NK cells: relevance for tumor surveillance

Normal (noninflamed) human skin contains a network of lymphocytes, but little is known about the homing and function of these cells. The majority of alphabeta T cells in normal skin express CCR8 and produce proinflammatory cytokines. In this study we examined other subsets of cutaneous lymphocytes, focusing on those with potential function in purging healthy tissue of transformed and stressed cells. Human dermal cell suspensions contained significant populations of Vdelta1(+) gammadelta T cells and CD56(+)CD16(-) NK cells, but lacked the subsets of Vdelta2(+) gammadelta T cells and CD56(+)CD16(+) NK cells, which predominate in peripheral blood. The skin-homing receptors CCR8 and CLA were expressed by a large fraction of both cell types, whereas chemokine receptors associated with lymphocyte migration to inflamed skin were absent. Neither cell type expressed CCR7, although gammadelta T cells up-regulated this lymph node-homing receptor upon TCR triggering. Stimulation of cutaneous Vdelta1(+) gammadelta T cell lines induced secretion of large amounts of TNF-alpha, IFN-gamma, and the CCR8 ligand CCL1. In contrast to cutaneous alphabeta T cells, both cell types had the capacity to produce intracellular perforin and displayed strong cytotoxic activity against melanoma cells. We therefore propose that gammadelta T cells and NK cells are regular constituents of normal human skin with potential function in the clearance of tumor and otherwise stressed tissue cells.     

Lenalidomide down regulates the production of interferon-γ and the expression of inhibitory cytotoxic receptors of human Natural Killer cells

Lenalidomide, a daughter molecule of Thalidomide, and IMIDs® are immunomodulatory drugs that have been described as having immunomodulatory properties and anti-tumor activity. The effect of Lenalidomide towards Peripheral Blood Mononuclear Cells (PBMC) has been studied and direct effects towards T cells have been described, such as an increase of interferon-γ (IFN-γ) and interleukin (IL)-2 production. As a consequence, it has been also described that IL-2 subsequently activates Natural Killer (NK) cells. Nevertheless, direct effects of Lenalidomide on NK cells from healthy volunteers have never been described, if searched. Here we show that Lenalidomide can inhibit the production of IFN-γ by NK cells from healthy donors. It also modifies the phenotype of NK cells through a decrease of the expression of Killer cell Immunoglobulin-like Receptors (KIRs) and NKp46. However, we did not detect consequence of these phenotype modifications on the cytotoxic potential of NK cells.     

Cytotoxicity of CD56(bright) NK cells towards autologous activated CD4+ T cells is mediated through NKG2D, LFA-1 and TRAIL and dampened via CD94/NKG2A

In mouse models of chronic inflammatory diseases, Natural Killer (NK) cells can play an immunoregulatory role by eliminating chronically activated leukocytes. Indirect evidence suggests that NK cells may also be immunoregulatory in humans. Two subsets of human NK cells can be phenotypically distinguished as CD16(+)CD56(dim) and CD16(dim/-)CD56(bright). An expansion in the CD56(bright) NK cell subset has been associated with clinical responses to therapy in various autoimmune diseases, suggesting an immunoregulatory role for this subset in vivo. Here we compared the regulation of activated human CD4(+) T cells by CD56(dim) and CD56(bright) autologous NK cells in vitro. Both subsets efficiently killed activated, but not resting, CD4(+) T cells. The activating receptor NKG2D, as well as the integrin LFA-1 and the TRAIL pathway, played important roles in this process. Degranulation by NK cells towards activated CD4(+) T cells was enhanced by IL-2, IL-15, IL-12+IL-18 and IFN-α. Interestingly, IL-7 and IL-21 stimulated degranulation by CD56(bright) NK cells but not by CD56(dim) NK cells. NK cell killing of activated CD4(+) T cells was suppressed by HLA-E on CD4(+) T cells, as blocking the interaction between HLA-E and the inhibitory CD94/NKG2A NK cell receptor enhanced NK cell degranulation. This study provides new insight into CD56(dim) and CD56(bright) NK cell-mediated elimination of activated autologous CD4(+) T cells, which potentially may provide an opportunity for therapeutic treatment of chronic inflammation.