白细胞介素2受体的两种蛋白及其功能

白细胞介素2(IL-2)是T 细胞生长因子,但除了维持T 细胞增殖以外,IL-2还可促进NK 活性、诱生LAK 细胞、促进B 细胞分泌抗体。这些功能是否由同一种受体介导,一直是一个令人感兴趣的问题。T 细胞经丝裂原或抗原激活后,细胞表面出现一种Tac 抗原,分子量为55KD,已证明这种p55蛋白就是IL-2受体。由于p55能结合IL-2,并且是在T 细胞激活时出现的,从而使人们相信p55就是介导IL-2生理作用的受体。但令人不解的是,在NK 细胞、LAK 细     

共培养体系中IL-15通过激活NK细胞ULBP1/NKG2D信号抑制食管癌细胞的迁移和侵袭北大核心CSCD

目的:探讨IL-15对食管癌细胞和自然杀伤(NK)细胞共培养体系中NK细胞活性以及对食管癌细胞迁移和侵袭的影响和机制。方法:qRT-PCR和Western blot检测人正常食管上皮细胞(HEEC)和食管癌细胞系TE-1中IL-15水平。TE-1与NK细胞共培养,共培养体系分为对照组(无处理)、IL-15组(0.2、0.4、0.8μg/ml的IL-15)、IL-15+anti-NKG2D组[UL16结合蛋白/自然杀伤组蛋白2D(ULBP1/NKG2D)的阻断剂anti-NKG2D联合IL-15(0.8μg/ml)]、anti-NKG2D组、IL-15+anti-ASIALO-GM1组[NK细胞抑制剂anti-ASIALO-GM1联合IL-15(0.8μg/ml)]及anti-ASIALO-GM1组。细胞划痕愈合实验和Transwell侵袭实验检测TE-1细胞的迁移和侵袭能力,CCK-8法检测NK细胞增殖率,Western blot检测各组NK细胞表面ULBP1/NKG2D表达,免疫共沉淀技术检测NKG2D与ULBP1的相互作用。结果:TE-1细胞中IL-15水平低于HEEC细胞(P<0.05)。0.2、0.4、0.8μg/ml IL-15处理共培养体系提高NK细胞增殖率,但降低TE-1细胞的迁移率和侵袭率(均P<0.05)。在TE-1与NK细胞的共培养体系中,IL-15组(0.8μg/ml)NK细胞膜蛋白ULBP1和NKG2D水平较对照组上调(均P<0.05);anti-NKG2D抑制了NKG2D表达,并抑制了NKG2D与ULBP1的相互作用,与IL-15(0.8μg/ml)组相比,IL-15+anti-NKG2D组NKG2D表达水平和NK细胞增殖率均降低(均P<0.05),但TE-1细胞的迁移率和侵袭率升高(均P<0.05),且NK细胞抑制剂anti-ASIALO-GM1与anti-NKG2D的作用效果一致。结论:IL-15通过激活细胞表面ULBP1/NKG2D信号促进NK细胞活性,从而抑制食管癌细胞的迁移和侵袭。     

IL-2和IFNa对自然杀伤功能的共同增强作用

用改良的单细胞细胞毒试验研究了IL-2和IFN_(?)对人外周血淋巴细胞NK的增强作用及共同增强作用。结果表明,IL-2或IFN_a单独预处理人外周血淋巴细胞(PBL)均不影响淋巴细胞与靶(K_(562))细胞的结合率,但能显著增加与靶细胞结合的淋巴细胞的杀伤率;同时用IL-2和IFN_a预处理人PBL后,淋巴细胞与靶细胞的结合率也没有显著改变,但结合的淋巴细胞的杀伤率显著高于单独用IL-2或IFN_a预处理后淋巴细胞的杀伤率,而且IL-2和IFN_a的增强作用存在加和性。这提示,IL-2和IFN_a能分别激活不同的NK细胞,即,NK细胞在其激活信号方面存在异质性。     

双表达外源性4-1BBL/IL-15的K562细胞活化外周血淋巴细胞的研究

为肿瘤过继免疫治疗开发体外激活T细胞、NK细胞的高效途径,研究双表达外源性4-1BBL和IL-15的K562细胞刺激外周血淋巴细胞活化的能力。采用分子克隆技术,分别将4-1BBL和IL-15基因插入双表达载体pVITRO-2,命名为pV4-1BBL-IL-15。经测序鉴定后,利用脂质体介导的转染及潮霉素筛选,获得稳定双表达4-1BBL、IL-15分子的K562细胞(K562/4-1BBL/IL-15)。经流式细胞仪(FACS)分选后,K562/4-1BBL/IL15细胞和K562细胞分别用丝裂霉素C处理,与外周血淋巴细胞孵育24 h,FACS检测淋巴细胞表面活化性受体CD69的表达。对NK细胞不仅同时检测活化性受体NKG2D的表达,还用乳酸脱氢酶释放法观察NK细胞受不同刺激细胞作用后,细胞毒活性的变化。结果显示受K562/4-1BBL/IL15细胞刺激后,T细胞CD69的表达无明显变化。γδT细胞CD69表达增长5倍。NK细胞CD69表达增长6倍,而NKG2D的表达增加1.5倍;NK细胞受K562/4-1BBL/IL15细胞作用72 h后,细胞毒活性明显提高。提示双表达4-1BBL/IL-15的K562细胞能够高效激活γδT细胞及NK细胞,有望用于肿瘤的过继免疫治疗。     

IL-2Rβ链研究近况

IL-2与IL-2受体(IL-2R)相互作用是机体免疫应答及调节的重要环节。近年来,借助于抗Tac单克隆抗体、重组IL-2(rIL-2)放射受体分析和标记IL-2受体交联分析等技术,人们正对IL-2的结合位点Tac抗原(因分子量55KD,故亦称P55)     

人早孕滋养细胞与蜕膜基质细胞共培养对外周NK细胞的影响

为了分析人早孕母-胎界面功能细胞对外周NK细胞表型及功能的调节作用,我们模拟母-胎界面微环境,建立滋养细胞和蜕膜基质细胞共培养系统,并将此共培养体系与外周NK细胞共培养,采用流式细胞术分析NK细胞的表型和细胞因子的表达,用细胞毒检测试剂盒检测NK细胞的细胞毒活性。研究发现,母-胎界面滋养细胞与蜕膜基质细胞共培养体系能够显著上调外周NK细胞抑制型受体KIR2DL1的表达,下调外周NK细胞杀伤性受体NKp44的表达;显著上调Th2型细胞因子IL-10的表达水平,下调外周NK细胞穿孔素perforin表达及其细胞毒活性。结果表明,母-胎界面功能细胞能够诱导外周NK细胞的耐受表型及Th2型优势,下调外周及蜕膜NK细胞的细胞毒活性,从而有利于形成母-胎界面免疫耐受微环境。     

巨细胞病毒感染和系统性红斑狼疮患者细胞免疫功能的相互关系

本文观察了27例系统性红斑狼疮(SLE)患者,巨细胞病毒(CMV)感染对共NK细胞活性无显著影响,但NK活性大于40％的SLE患者CMV感染率较NK活性小于40％者明显低;CMV感染使患者白细胞介素2(IL-2)水平明显降低,只有高水平(大于110U/ml)IL-2的SLE患者CMV感染率低于IL-2水平低者。CMV感染对SLE患者T细胞亚群CD抗原表达影响不大。     

慢性肺心病患者NK细胞活性及其对IL-2、IFN-γ的反应

本文检测30例慢性肺心病患者外周血NK细胞活性,并探讨重组人IL-2、IFN-γ在体外对患者NK细胞活性的影响。结果发现肺心病患者NK细胞活性明显低于正常对照组(p<0.01),且在急性加重期NK细胞活性下降更为显著,IL-2、IFN-γ在体外能明显提高肺心病患者的NK细胞活性。     

烧伤后血清IL-2受体可能是一种免疫抑制介质

T 细胞的增殖分化需要T 细胞生长因了白细胞介素-2(IL-2)才能发挥作用,已经证实,IL-2的产生及活性均可受烧伤血清的抑制。烧伤病人T 细胞免疫功能下降与血清中存在可溶性抑制介质有关,本文对此进行了研究。作者设烧伤病人组(平均烧伤面积52%)和正常人对照组。用混合淋巴细胞反应(MLR)观察烧伤和正常血清对外周血单个核细胞(PBMC)增殖反应的影响;用抗IL-2受体(Tac)的单克隆荧光抗体和流式细胞仪观察烧伤、正常血清对PBMC 表达     

瘤型麻风动物模型的NK细胞活性的体外测定

本文报道了瘤型麻风小鼠模型中脾脏NK细胞活性的体外测定,以及加入外源性IL-2对这一活性的影响。结果表明,随着感染时间的延长,小鼠脾脏中NK细胞活性逐渐降低。感染1月小鼠的NK细胞活性明显低于正常小鼠,感染3月小鼠的NK细胞活性较感染1月小鼠更低(P值均<0.01)。将含有IL-2的上清液加入NK细胞活性检测系统中,发现外源性IL-2可逆转感染小鼠的NK细胞活性,使其恢复达正常水平。结合IL-2与NK细胞活性在免疫调节中的作用,对瘤型麻风动物模型的特殊表现作了讨论。     

Prevention and reversal of delta-9-tetrahydrocannabinol induced depression of natural killer cell activity by interleukin-2

The effects of delta-9-tetrahydrocannabinol (THC) on NK cell activity were studied. Previously, we reported that incubation of human peripheral blood mononuclear cells in THC resulted in an inhibition of natural killer (NK) cell activity. The present study examined the mechanism(s) of the decrease in NK cell activity. The inhibition of killing by NK cells was not due to a failure of NK cells to bind to K562 target cells. Furthermore, indomethacin did not abrogate the THC-mediated effect, suggesting that prostaglandins are not involved in the process leading to suppression of NK cell activity. However, NK activity was partially restored if cells, pretreated with THC, were washed to remove excess drug and then incubated overnight in fresh medium before assay. Addition of 1-100 U IL-2, either during pretreatment with THC or during overnight incubation, precluded or promoted the reversal of the inhibition of NK cell cytotoxicity. We conclude that the regulatory mechanism(s) involved in depression of NK cell cytotoxicity by THC is significantly influenced by IL-2.     

Delta-9-Tetrahydrocannabiol (THC) decreases the number of high and intermediate affinity IL-2 receptors of the IL-2 dependent cell line NKB61A2

Treatment of the cloned NK-cell line (NKB61A2) with the major psychoactive marijuana component, delta-9-tetrahdyrocannabinol (THC), for 24 h suppressed IL-2-induced proliferation of these cells in the cytokine concentration range of 0.25 – 10 pM suggesting that the drug inhibits the functional activity of the high affinity IL-2R. The proliferation inhibitory effect of THC was accompanied by a decrease in the number of high and intermediate affinity IL-2 binding sites as measured by equilibrium binding studies. However, the expression of Tac protein on the surface of these cells was increased as determined by flow cytometry analysis. THC was also shown to decrease proliferation and the number of IL-2 binding sites of cells previously pulsed with IL-2 and then treated with the drug in the absence of IL-2. These results suggest that THC inhibits IL-2-induced proliferation by modulating the expression of high affinity IL-2 receptors (α/β) required for cell activation and also suppresses the ongoing process of functional receptor expression and clonal expansion of cells previously activated by IL-2. Because the number of intermediate binding sites is decreased following drug treatment along with an increase in the expression of Tac protein (α chain), the lowering of high affinity sites possibly results from a drug-induced depression of β chain expression.     

Synergistic activation of human natural killer cell cytotoxicity by histamine and interleukin-2

Interleukin-2 (IL-2) is recognized as a major activating signal for human natural killer (NK) cells. The presence of monocytes alters NK cell responsiveness to IL-2. Thus, while IL-2 effectively augments NK cell cytotoxicity (NKCC) in monocyte-depleted NK effector cells, it is relatively ineffective or even suppressive for NK cells in monocyte-containing, NK-cell-enriched mononuclear cell fractions. Here we report that concomitant treatment with IL-2 and the biogenic amine histamine synergistically augmented NKCC against K562 and Daudi target cells of CD3-/CD16+ human NK cells in the presence but not in the absence of monocytes. Addition of peripheral-blood monocytes, recovered by countercurrent centrifugal elutriation, to purified NK cells abrogated IL-2 induced NK cell activation, reconstituted the synergistic, NK-activating effects of histamine and IL-2, and strongly reduced baseline NKCC. The effects of histamine on baseline NKCC and on NK cell responsiveness to IL-2 were related to counteraction of monocyte-mediated NK cell suppression. By contrast, histamine did not affect baseline or IL-2-induced NKCC in mixtures of NK cells and monocytes when the latter cells were recovered after adherence. The effect of histamine on NK cell responsiveness to IL-2 was mediated by H2-type histamine receptors, as judged by mimicry exerted by the specific H2 receptor agonist dimaprit, but not by an H2-receptor-inactive derivative of this compound, N-methyldimaprit, and blocking by the H2 receptor antagonist ranitidine. Experiments in which monocytes and nonadherent NK cells were separately pretreated with ranitidine prior to histamine treatment suggested that NK-regulatory effects of histamine were mediated by H2 receptors on monocytes. Our data suggest that histamine may provide an important signal in the regulation of NK cell responsiveness to IL-2.     

Selective inhibition of natural killer but not natural cytotoxic activity in a cloned cell line by delta-9-tetrahydrocannabinol.

Natural killer (NK) and natural cytotoxic (NC) activities are spontaneously generated against certain tumors in vitro and their contribution to tumor immunity is being extensively investigated. We report here that the interleukin-2 (IL-2)-dependent murine cell line, NKB61A2, which we recently found to express both NK and NC functions, can be modulated selectively by 9 delta-tetrahydrocannabinol (THC). THC, a major psychoactive metabolite of marijuana, could significantly inhibit NK activity without altering NC activity in NKB61A2 cells. Inhibition of NK function occurred at a post-binding stage because effector/target conjugation was unaffected by THC. With regard to NC function, neither the cytotoxic activity of the cells nor release of tumor necrosis factor was interrupted by THC. Therefore, THC may provide a useful tool for dissociating the mechanism of NK and NC activities within a single population of cells.     

Role for adapter proteins in costimulatory signals of CD2 and IL-2 on NK cell activation.

Natural killer (NK) cells participate in both innate and adaptive immunity through the prompt secretion of cytokines and ability to lyse virally infected cells or tumor cells. Triggering of NK cells requires aggregation of surface receptors such as CD2 and CD16, and NK cell activity can be augmented in vitro by stimulation with IL-2. In this study, we examined the role of adapter proteins in the increased NK activation following CD2 crosslinking and IL-2 stimulation of NK3.3 cells. NK3.3 cells lysed NK-sensitive K562 cells in a CD2-dependent manner, and IL-2 markedly enhanced lytic activity in a 4h cytotoxic assay. IL-2 also enhanced spontaneous and CD2-mediated granule exocytosis from NK3.3 cells. CD2 crosslinking markedly induced tyrosine phosphorylation of Cbl associated with Grb2 or CrkL, Shc and LAT, compared with IL-2 stimulation. However, costimulation of IL-2 with CD2 crosslinking remarkably enhanced associations of Grb2-Shc and CrkL-Cbl, compared to IL-2 stimulation or CD2 crosslinking alone. In vitro binding studies using GST-fusion proteins revealed that interactions of Grb2-Shc and CrkL-Cbl were mediated through each SH2 domain in tyrosine phosphorylation-dependent manner. Furthermore, CD2 crosslinking, but not IL-2 stimulation, markedly induced tyrosine phosphorylation of LAT. Thus, tyrosine phosphorylation of different adapter proteins and consequent interactions between signaling molecules described here may explain the molecular mechanisms of the additive effects of IL-2 stimulation and CD2 crosslinking on NK cell activation.     

Disordered expression of inhibitory receptors on the NK1-type natural killer (NK) leukaemic cells from patients with hypersensitivity to mosquito bites

Recent studies have revealed the existence of a distinct type of NK cell leukaemia of the juvenile type, which presents with hypersensitivity to mosquito bites (HMB) as an essential clinical manifestation and is infected with clonal Epstein-Barr virus (EBV). This disorder is thus called HMB-EBV-NK disease and has been reported in Orientals, mostly from Japan. We investigated the profile of cytokine production and the expression of both types of NK inhibitory receptors, i.e. CD94 lectin-like dimers and killer-cell immunoglobulin-like receptors, in NK leukaemic cells from three patients with HMB-EBV-NK disease. It was found that freshly isolated NK leukaemic cells expressed mRNA for interferon-gamma (IFN-gamma) and additionally produced IL-10 upon stimulation with IL-2, indicating that the NK cells were of NK1 type. More than 98% of NK cells from the patients bore CD94 at a higher level than did normal NK cells, whereas p70 or NKAT2, belonging to immunoglobulin-like receptor, was not expressed in those NK cells. Freshly isolated leukaemic NK cells transcribed mRNA for CD94-associated molecule NKG2C at an abnormally high level, and upon stimulation with IL-2 and/or IL-12 they expressed NKG2A as well. The disordered expression of these inhibitory receptors not only provides some insights into the pathogenesis of HMB-EBV-NK disease but also can be used as phenotypic markers for the diagnosis of this type of NK cell leukaemia.     

Prostaglandin E2 is a potent regulator of interleukin-12- and interleukin-18-induced natural killer cell interferon-gamma synthesis

Synthesis of interferon (IFN)-gamma by natural killer (NK) cells is an important pro-inflammatory event with interleukin (IL)-12 and IL-18 playing major inductive roles. However, other temporal events are likely to regulate such processes and as prostaglandin E2 (PGE2) is ubiquitous during inflammation this study tested the hypothesis that PGE2 was capable of directly modulating cytokine-induced NK cell IFN-gamma synthesis in the absence of other immune cells. Using homogeneous NK cell lines to establish direct effects, PGE2 (0.1-1 micro m) was found to suppress NK cell IFN-gamma synthesis and antagonized the potent synergistic IFN-gamma-inducing effects of IL-12 and IL-18. The actions of PGE2 were mimicked by synthetic PGE2 analogues including misoprostol and butaprost. The selective EP2 receptor agonist butaprost, but not the EP1/EP3 agonist sulprostone, suppressed IFN-gamma synthesis and exclusively competed with PGE2 for receptor binding on NK cells. Further analysis showed that PGE2 did not modulate IL-12 receptor mRNA expression and the effects of PGE2 could be mimicked by the phosphodiesterase inhibitor 3-iosobutyl-1-methylxanthine. The absence of demonstrable receptor modulation coupled with the observed suppression of IFN-gamma synthesis by both EP2 receptor-selective agonists and IBMX suggest that PGE2 acts directly on NK cells via EP2 receptors with its downstream effects on cAMP metabolism. This conclusion is further supported by findings that PGE2 and its analogues consistently elevated levels of cAMP in NK cells. The ability of PGE2 to antagonize the potent inductive signal provided by the combination of IL-12 and IL-18 supports the concept that PGE2 may play an important role in limiting innate inflammatory processes in vivo through direct suppression of NK cell IFN-gamma synthesis.     

Enhancement of Cytotoxic Activity of Natural Killer Cells by Interleukin 2, and Antagonism between Interleukin 2 and Adenosine Cyclic Monophosphate

Two cytokines, interferon (IFN) and interleukin 2 (IL-2), activate murine natural killer (NK) cells in vitro. Together both factors synergize considerably. Antibody against IFN eliminates the response of NK cells to IFN as well as to IL-2, whereas antibody against IL-2 blocks the effect of IL-2 but not of IFN. These findings as well as previous observations imply that both factors act on the same cell but have different roles. We suggest that IFN induces NK cell activation and IL-2 enhances this effect. Further studies revealed that besides inducing cytotoxicity in NK cells IFN induces the production of prostaglandin E (PGE) which inhibits NK cell activation. We propose therefore that IFN has a dual effect on NK cells: it induces NK cells to become cytotoxic and initiates a negative feedback by increasing the production of PGE. IL-2, which synergizes with IFN in the activation of NK cells, ceases to do so when the negative feedback (PGE-mediated) is blocked with indomethacin. We infer that IL-2 enhances NK cell activity by interfering with the negative feedback rather than by aiding NK cell activation.     

Target cells for an immunosuppressive cytokine, glycosylation-inhibiting factor.

Receptors for bioactive glycosylation-inhibiting factor (GIF) were demonstrated using a bioactive mutant of recombinant human (rh) GIF, which is comparable to the suppressor T (Ts) cell-derived bioactive GIF in its affinity for the receptors on helper T (Th) hybridoma cells. Both naive T and B cells in normal mouse spleen lacked GIF receptors. However, presentation of specific antigen to naive T cells resulted in the expression of the receptors on activated T cells. Furthermore, activation of small resting B cells with F(ab')2 fragments of anti-mouse IgM plus IL-4, lipopolysaccharide (LPS) plus IL-4 or LPS plus dextran sulfate induced the expression of the receptors within 48 h of B cell stimulation. It was also found that NK T cells freshly isolated from mouse spleen, but not conventional NK cells, expressed receptors for GIF. CD4(+) and CD4(-) subpopulations of NK T cells showed a similar binding capability. Mature dendritic cells derived from bone marrow did not bear the receptors. The dissociation constant (Kd) of the interaction between the bioactive rhGIF mutant and the high-affinity receptors was 10-100 pM, whereas inactive wild-type rhGIF failed to bind to the receptors. A bioactive derivative of rhGIF suppressed both IgG1 and IgE synthesis by purified B cells activated by LPS and IL-4, indicating that the binding of bioactive GIF to its receptors on activated B cells results in suppression of their differentiation.