PFP、GrB的共表达杀伤人喉癌Hep-2细胞的体外研究

为探讨穿孔素(PFP)、颗粒酶B(GrB)共表达对人喉癌(Hep-2)细胞生长的抑制及其诱导该细胞的凋亡作用,采用RT-PCR的方法从人的喉癌组织浸润淋巴细胞中扩增全长PFP、GrB的cDNA片段,构建共表达重组体pVAX1-PIG,并将其转染入人的Hep-2细胞株中。收集转染后的Hep-2细胞,采用软琼脂集落形成实验、MTT法、原位末端标记法(TUNEL)、流式细胞仪(FCM)检测分析各组人Hep-2细胞的生长抑制及其凋亡情况。结果显示pVAX1-PIG转染组的集落形成数目比空白对照组与pVAX1转染组明显减少(P<0.05),MTT检测结果显示对照组细胞生长速度比pVAX1-PIG转染组要快。TUNEL染色、FCM法检测均显示pVAX1-PIG转染组的Hep-2细胞大量凋亡且其凋亡率显著高于对照组(P<0.05)。因此,PFP、GrB的共表达能够抑制人Hep-2细胞的生长并且可以诱导该细胞的凋亡。     

Immunohistochemical study of necrotizing lymphadenitis: A possible mechanism for apoptosis involving perforin and granzyme-producing cytotoxic T cells

Twelve lymph node specimens with necrotizing lymphadenitis and which had florid necrotic lesions were studied immu-nohistochemically. The majority of viable lymphoid cells in the necrotic foci were CD8+ lymphocytes and KP1+ or PGM1+ phagocytizing macrophages. The CD8+ T cells were Leu1+, Leu2+, Leu3^--, Leu4+, Leu5b+, Leu7^--, Leu11b^- and Leu19^--, indicating a suppressor/cytotoxic T cell phenotype. In addition, the cytoplasm of these cells was immunoreactive for perforin and granzyme B in a granular pattern. With a nick end-labeling technique, fragmented nuclei and some lymphoid cell nuclei were positively stained. These results suggest that the necrosis in necrotizing lymphadenitis is apoptotic necrosis of T cells targeted by CD8+, perform and granzyme-producing, activated cytotoxic T cells, supporting a viral infection etiology.     

gammadelta T cells of human early pregnancy decidua: evidence for cytotoxic potency

The immune compromise in decidua allows a semiallogeneic fetus to survive without impairing the ability of the maternal immune system to fight infections. Cytotoxic mechanisms are likely to be important in this compromise. Using RT-PCR, immunoflow cytometry and immunoelectron microscopy, the cytotoxic potential of isolated human decidual gammadelta T cells was studied. mRNA for perforin (Pf), granzymes A and B, granulysin and Fas ligand (FasL) was simultaneously expressed in decidual gammadelta T cells. Pf and FasL were not expressed on the cell surface. However, the cells constitutively synthesized Pf and stored it in cytolytic granules. Within the granules Pf mainly resided in the granule core formed by Pf-containing microvesicles. Ultrastructurally, three groups of Pf-containing granules were distinguished. They probably represent different stages of granule maturation in a process where Pf-containing microvesicles first attach to the core cortex and then are translocated across the cortex into the core. Presynthesized FasL was also stored in the core and microvesicles of the cytolytic granules. Upon degranulation by ionomycin/Ca(2+) treatment, FasL was rapidly translocated to the cell surface, demonstrating that its surface expression was not controlled by de novo biosynthesis. Thus decidual gammadelta T cells appear to perform Pf- and FasL-mediated cytotoxicity utilizing a common secretory mechanism based on cytolytic granule exocytosis. The first cytochemical visualization of lipids in the cytolytic granules is provided. These intragranular lipids probably wrap up the core and participate in packaging of the cytotoxic proteins as well as in the killing process. An ultrastructural model of a cytolytic granule is presented.     

The cytolytic activity of natural killer cells is not involved in the restriction of Mycobacterium avium growth

Severe combined immunodeficiency (SCID) mice were used to analyze the role of NK cells in resistance to Mycobacterium avium. The neutralization of IFN-gamma in these animals led to an exacerbation of the infection associated with a reduction in macrophage activation, suggesting a role for NK cells in innate immunity to mycobacteria. In contrast, administration of anti-asialo-GM(1) polyclonal serum or mAb specific for Thy1.2 did not affect mycobacterial growth or macrophage activation despite causing the almost complete abrogation of the natural cytolysis of a tumor cell target. Treatment with anti-asialo-GM(1)-specific serum depleted only two-thirds of the Thy1.2+ spleen cells, and anti-Thy1.2 treatment allowed for the persistence of a small number of cells still exhibiting an NK cell marker recognized by mAb DX5 and able to express IFN-gamma as analyzed by flow cytometry. In vivo treatment of B6.SCID mice with anti-NK1.1 mAb again failed to affect resistance to infection and allowed for the persistence of 2-8% of IFN-gamma-producing cells, many of them still expressing the DX5 marker. In vitro depletion studies showed that removal of IFN-gamma-expressing cells required the combined action of anti-Thy1.2, anti-Ly49C and DX5 antibodies in the presence of complement. Our data show that resistance to M. avium mediated by NK cells is independent of their cytolytic activity, and that there is a marked phenotypic and functional heterogeneity of the NK cell lineage in vivo during infection.     

Role of natural killer cytotoxic factors in the mechanism of target-cell killing by natural killer cells

Studies on the mechanism of cell-mediated cytotoxicity (CMC) have suggested a stimulus-secretion model and implicated a role of soluble cytotoxic mediators. Our studies in the natural killer (NK) system provide several lines of evidence for the involvement of natural killer cytotoxic factors (NKCF) in NK CMC and led to the development of a model for the NK lytic mechanism. This model delineates several interactions between NK cells and targets that are deemed necessary to achieve target-cell lysis. The first stage is the interaction of the effector with the target cell, resulting in contact and adhesion. This is presumably mediated by NK recognition structures and target-cell structures. Following binding, the target cell stimulates the NK cell to release NKCF. This step is functionally distinct from the initial effector-target binding. The trigger mechanism for release of NKCF appears to be dependent on protein kinase C. The released NKCF binds to NKCF binding sites on the target cell followed by processing or internalization and, ultimately, resulting in cell death. This model has been shown to be useful in investigating the mechanism of defective NK activity in certain disease states. Biochemical analysis and comparative studies suggest that NKCF is a distinct molecule from other cytotoxins studied to date. The studies in the NK CMC system supporting a role of cytotoxic mediators also suggest a possible role for cytotoxic factors in other cytotoxic systems. Furthermore, the selective susceptibility to lysis of tumor or infected cells by NKCF suggests a possible role of their effectiveness inin vivo therapy.     

Decrease of cytotoxic T cells in allergic asthma correlates with total serum immunglobulin E

BACKGROUND: Allergic asthma has been linked to an increase in T-helper type 2-like cytokines and T cells, but there is growing evidence for a role of lymphocyte-mediated cytotoxic mechanisms in the pathogenesis of asthma. Therefore, we investigated the cytotoxic potential of different lymphocyte subpopulations in patients with allergic asthma. METHODS: Granzyme A, B, K, and perforin expression in peripheral blood lymphocytes was analyzed using flow cytometry. Soluble granzymes were measured in serum using specific enzyme-linked immunosorbent assays. RESULTS: Asthmatics had significantly decreased percentages of granzyme and perforin-positive CD4 T cells compared with non-atopic controls. In patients with asthma, the granzyme B and perforin-positive subset of CD8(+) T cells and natural killer T cells, which represent more differentiated cell populations, were significantly reduced, while this was not observed in the less differentiated granzyme K(+) subsets. In addition, the serum concentrations of granzyme B were significantly reduced in patients with asthma, while granzyme K concentrations were not different. Interestingly, there was a negative correlation between granzyme A, B and perforin expression in T cell subsets as well as serum granzyme B concentrations and total serum immunglobulin E. In CD3-negative natural killer cells, no differences in granzyme or perforin expression between patients with asthma and controls were detected. CONCLUSION: In allergic asthma, cytotoxic T lymphocyte subsets of a more differentiated phenotype are significantly decreased and this is correlated to serum immunglobulin E levels.     

Progesterone-induced blocking factor inhibits degranulation of natural killer cells.

PROBLEM: During the first trimester of pregnancy, nonclassical (CD3-, CD56+, CD16-, perforin [P]bright+) natural killer (NK) cells comprise the major decidual lymphocyte population. These cells, in spite of their high perforin content, exert a low cytolytic activity. Peripheral blood lymphocytes of healthy pregnant women produce progesterone-induced blocking factor (PIBF), which inhibits NK activity. PIBF-producing cells are likely to be present in decidua and might contribute to low decidual NK activity. METHOD OF STUDY: Decidual cells obtained from elective pregnancy termination were double labeled for CD56 and PIBF. We tested the effect of PIBF on perforin liberation by activated peripheral blood NK cells. RESULTS: Sixty percent of decidual lymphocytes were CD56 + and expressed PIBF at the same time. PIBF-treated and untreated peripheral blood NK cells were incubated with K-562 cells, and perforin content of target conjugated NK cells was detected with immunocytochemistry. PIBF treatment of peripheral blood lymphocytes significantly reduced lysis of K-562 cells. Among target bound lymphocytes in PIBF-treated samples, we found a significantly (P < 0.01) higher rate of P+ cells than in untreated samples. CONCLUSIONS: These data suggest that PIBF inhibits cytotoxicity of NK cells via a block of degranulation, and since decidual NK cells are PIBF+, it cannot be ruled out that this effect of PIBF contributes to low decidual NK activity.     

Lymphomatous features of aggressive NK cell leukaemia/lymphoma with massive necrosis, haemophagocytosis and EB virus infection

AIMS : Aggressive natural killer (NK) cell leukaemia will be categorized as a distinct entity in the new WHO classification of malignant lymphomas. However, its non-leukaemic features remain unclear. We therefore investigated the morphological and immunophenotypic features of this lymphoma. METHODS AND RESULTS : Four cases with aggressive NK cell lymphoma were morphologically and immunohistochemically studied. All cases followed an aggressive course with death occurring within about 3 months of initial presentation. In these cases, the neoplastic cells disseminated throughout systemic lymph nodes and invaded various tissues and organs. The lymphoma cells were large cells showing nuclear irregularity and a pattern of sinusoidal invasion in lymph nodes. Apoptosis and coagulation necrosis were both frequently observed. Haemophagocytosis was observed in all cases. Neoplastic cells in paraffin-embedded tissue specimens from these patients had CD3(CD3epsilon)+ CD56(123C3)+ granzyme+ TIA-1+ EBERT+ CD43(MT1)- CD45RO(UCHL-1)- CD57(Leu7)- CD20(L26)- phenotypes. In the two cases where tissue was available for immunohistochemical study in frozen sections, neoplastic cells showed CD56(Leu19)+ perforin+ Fas ligand(FasL)+ CD2(Leu5b)- CD3(Leu4)- CD4(Leu3)- CD5(Leu1)- CD7(Leu9)- CD8(Leu2)- betaF1- TCRdelta1- phenotypes. CD16(Leu11b) was positive in one case. CONCLUSIONS: : Natural killer cell lymphomas appear to represent a non-leukaemic counterpart of aggressive natural killer cell leukaemia, a relationship similar to that in adult T-cell leukaemia/lymphoma. Awareness and diagnosis of this aggressive lymphoma is important because of its fulminant course.     

血浆置换术在人工肝治疗急性有机磷农药中毒中的作用

目的探讨血浆置换术在人工肝治疗急性有机磷农药中毒中的作用。方法回顾性分析2005年至2007年收治的56例急性有机磷农药中毒病例资料，其中A组23例患者行常规治疗和人工肝治疗，B组33例患者行常规治疗、人工肝治疗和血浆置换，比较两组血清生化指标和临床效果。结果B组与A组比较，有更低的白细胞数（WBC）、血总胆红素（TBiL）、谷丙转氨酶（ALT）、肌苷（Cr）、凝血酶原时间（PT）水平和更低的并发症发生率及死亡率，有更高的胆碱酯酶（CHE）水平和治愈率。结论血浆置换术在抢救有机磷农药中毒中的效果明显。     

人早孕期蜕膜基质细胞下调蜕膜NK细胞杀伤活性

通过分析人早孕期蜕膜基质细胞(decidual stromal cell,DSC)对蜕膜NK细胞(dNK)表面趋化因子受体CXCR4与细胞内颗粒酶B表达水平的影响,研究早孕蜕膜基质细胞对局部NK细胞的训导作用。收集早孕蜕膜组织,分离DSC及蜕膜免疫活性细胞,进一步通过磁珠分选蜕膜CD3-CD56bright NK细胞,将分离的蜕膜NK细胞与DSC按1∶1比例共培养24h,收集蜕膜NK细胞,流式细胞仪检测其表面趋化因子受体CXCR4和细胞内颗粒酶B(granzyme B)的表达水平。结果显示,与对照组相比,在与DSC细胞共培养之后,趋化因子受体CXCR4+NK细胞的百分率明显上升,而蜕膜NK细胞内颗粒酶B阳性率显著下降(P<0.05)。结果表明,人早孕母-胎界面DSC细胞上调蜕膜NK细胞表面趋化因子受体CXCR4的表达,下调NK细胞内颗粒酶B的表达水平,可能抑制其杀伤活性。     

雌激素对天然杀伤细胞的作用

为探讨雌激素对NK细胞的作用,在不同时间把不同剂量的雌激素加入培养体系中,分析雌激素对无和有外来刺激原刺激NK细胞的影响。结果显示培养开始加入生理剂量、低于生理剂量和超生理剂量的雌激素均可明显抑制NK细胞的增殖;培养48 h后加入相同剂量的雌激素,生理剂量和低于生理剂量雌激素仍可明显抑制NK细胞的增殖,超生理剂量雌激素非但不能抑制反而使NK细胞的数量增加。     

TLR7/8配体(R848)对人NK细胞杀伤功能的作用及其机制的探讨

目的研究R848对人自然杀伤细胞(NK)杀伤功能的作用及其机制。方法分离健康志愿者外周血单个核细胞(PBMC)、纯化NK细胞,加或不加R848进行培养。分别在0、2、6、24、48h收集培养细胞,流式细胞术检测R848对NK细胞表面活化分子CD25和CD69表达的影响;检测R848活化的NK细胞杀伤靶细胞K562的作用、通过检测颗粒酶A、B、穿孔素、TRAIL和NK细胞与靶细胞共孵育后CD107a/b的表达,探讨R848促进NK细胞的杀伤功能机制。结果 R848活化的NK细胞在培养24h时CD69和CD25分子的表达百分率和平均荧光密度达到峰值,随后活化分子的表达有所下降;R848活化的NK细胞对靶细胞的杀伤功能明显增强,TRAIL在不同NK细胞亚群的表达显著增加(P0.05)。当NK细胞与K562共孵育后,R848活化的NK细胞表面CD107a/b的表达较未刺激条件明显增加。结论 R848可直接作用于NK细胞促进其杀伤功能,其作用机制与NK细胞活化后释放颗粒酶和穿孔素增加,并且TRAIL的表达增加有关。     

Lipophilic statins suppress cytotoxicity by freshly isolated natural killer cells through modulation of granule exocytosis

NK cells, a component of the innate immune system, provide a first line of defense against viral infections and malignancies, interact with the adaptive immune system and have a role in rejection of allogeneic bone marrow transplants and solid allo- and xenotransplants. Immunoregulatory activity by the anti-hypercholesterolemia agents, 3-hydroxy-3-methyl-glutaryl Coenzyme A (HMG-CoA) reductase inhibitors, known as statins, has recently been reported. We analyzed the effects of three statins on human NK cell cytotoxicity. Two lipophilic statins (simvastatin and fluvastatin) suppressed the cytotoxic activity of fresh and IL-2-stimulated NK cells, while pravastatin, a hydrophilic statin, did not. Suppression was not associated with changes in intracellular perforin, granzyme A or granzyme B levels, or with changes in expression of leukocyte function-associated antigen-1, an integrin known to regulate NK activity and reported to be altered by statin treatment. Decreased cytotoxicity was associated with decreased CD107a surface expression, indicating that the exocytosis pathway was compromised by simvastatin and fluvastatin but not by pravastatin. Mevalonate, the immediate downstream product of HMG-CoA reductase, partially reversed the effect of lipophilic statins on cytotoxicity and CD107a expression. Lipophilic statins also suppressed the release of the granule component, granzyme B, by IL-2-activated NK cells following stimulation with K562. That lipophilic statins suppress NK cell activity through inhibition of the exocytosis pathway suggest an additional potential role for statins in inhibition of transplantation responses.     

Memory responses of natural killer cells

Natural killer (NK) cells have traditionally been classified as a cellular component of the innate immune system, given their ability to rapidly produce effector cytokines and kill infected or transformed cells without prior exposure. More recently, NK cells have been shown to possess features of adaptive immunity such as clonal expansion, longevity, and robust recall responses. NK cell memory can be broadly divided into two categories: antigen-specific and antigen-independent. In the first case, exposure to certain viral or hapten stimuli endows NK cells with antigen-specific immunological memory, similar to T and B cells. In the second case, exposure of NK cells to specific cytokine milieus can imprint long-lasting changes on effector functions, resulting in antigen-independent memory-like NK cells. In this review, we discuss the various conditions that promote generation of these two categories of memory NK cells, and the mechanistic requirements underlying these processes.     

Thymic stromal lymphopoietin augments the cytolytic activity of the human natural killer cell line NK-92

Culturing the human natural killer cell line NK-92 for 24 h in the presence of thymic stromal lymphopoietin (TSLP) potentiated its cytotoxic capacity against the erythroleukemia cell line K562. Longer incubation times did not augment the NK activity any further. No synergistic effects with respect to either proliferation or cytotoxicity were observed when TSLP was mixed with suboptimal concentrations of IL-2. FACS analysis of the NK-92 cells indicated expression of TSLPR but not the other component of the TSLP receptor complex, namely IL-7Ralpha. Some of the surface molecules known to be involved in NK cell-mediated cytotoxicity were also monitored. None of the receptors analyzed altered their expression to any major extent upon culture in TSLP or IL-2. However, a limited number of NK-92 cells were observed that had a rather low CD94/NKG2A expression, which increased upon stimulation with TSLP or IL-2.     

Ligation of CD8alpha on human natural killer cells prevents activation-induced apoptosis and enhances cytolytic activity

It has been previously shown that the subset of human natural killer (NK) cells which express CD8 in a homodimeric alpha/alpha form are more cytotoxic than their CD8- counterparts but the mechanisms behind this differential cytolytic activity remained unknown. Target cell lysis by CD8- NK cells is associated with high levels of effector cell apoptosis, which is in contrast to the significantly lower levels found in the CD8alpha+ cells after lysis of the same targets. We report that cross-linking of the CD8alpha chains on NK cells induces rapid rises in intracellular Ca2+ and increased expression of CD69 at the cell surface by initiating the influx of extracellular Ca2+ ions. We demonstrate that secretion of cytolytic enzymes initiates NK-cell apoptosis from which CD8alpha+ NK cells are protected by an influx of exogenous calcium following ligation of CD8 on the NK-cell surface. This ligation is through interaction with fellow NK cells in the cell conjugate and can occur when the target cells lack major histocompatibility complex (MHC) Class I expression. Protection from apoptosis is blocked by preincubation of the NK cells with anti-MHC Class I antibody. Thus, in contrast to the CD8- subset, CD8alpha+ NK cells are capable of sequential lysis of multiple target cells.     

HLA-G inhibition of NK-cell cytolytic function is uncoupled from tumor cell lipid raft reorganization

HLA-G is a non-classical HLA class I molecule with tolerogenic properties and restricted tissue distribution. The expression of HLA-G can be induced by tumors thus providing an efficient way to escape the anti-tumoral immune response. Although lipid rafts regulate diverse immunological mechanisms their relationship with HLA-G remains controversial. Our results show that HLA-G-mediated inhibition of both the interaction between NK and tumor cells, and of intracellular calcium flux in NK cells conjugated to their target cells were independent of lipid raft integrity. In addition, cytotoxicity assays indicated that HLA-G continued to efficiently inhibit NK-cell cytolytic function in several different tumor cells independently of lipid raft integrity. Confocal microscopy with 3D reconstruction combined with biochemical analysis showed that HLA-G was mainly localized outside the lipid rafts of tumor cells after cross-linking with specific antibody and remained excluded from lipid rafts during interaction with the ILT2 inhibitory receptor of NK cells. This study indicates that the inhibitory function of HLA-G is uncoupled from lipid raft organization, further distinguishing HLA-G from classical HLA molecules and providing novel information in the understanding of tumor immune escape mechanism mediated through HLA-G.     

Analysis of the activating receptors and cytolytic function of human natural killer cells undergoing in vivo differentiation after allogeneic bone marrow transplantation

Patients undergoing allogeneic bone marrow transplantation offer a unique system to analyze NK cell development in vivo. We analyzed NK cells from 23 such patients to assess the acquisition of activating receptors. Four patients displayed an immature NK cell surface phenotype at engraftment, as their cells were CD16(-)KIR(-) and NKG2D(-) but expressed low levels of NKp46, NKp30, 2B4 and NKG2A. These NK cells had particularly low cytolytic activity against the HLA-class-I(-) melanoma F01 cell line and the 721-221 EBV-infected B cell line. Moreover, cytoxicity was inhibited upon mAb-mediated crosslinking of 2B4. Analysis of NK cells at day 30 after bone marrow transplantation revealed the occurrence of both phenotypic and functional maturation. These data are in agreement with a previous in vitro study showing that immature NK cell precursors express CD16, NKG2D and KIR only at a late stage of differentiation and also express inhibitory 2B4. Our present study allows a better understanding of the NK cell differentiation in vivo.