真核表达的重组猪单链IL-12生物学活性的研究

目的:真核表达重组猪单链IL-12(pscIL-12)并鉴定表达的pscIL-12的生物学活性。方法:采用梭华-SofastTM将pcDNA3.1(+)-pscIL-12转入CHO-K1细胞,ELISA法测定细胞培养上清中pscIL-12的表达水平;MTT法检测细胞培养上清对NK细胞杀伤作用的影响;ELISA法测定细胞培养上清刺激人PBMC分泌IFN-γ的水平;流式细胞术(FCM)检测细胞培养上清对人淋巴母细胞增殖水平的作用。结果:融合基因pscIL-12在CHO-K1细胞中表达产物pscIL-12融合蛋白含量较高;生物学活性鉴定表明:pscIL-12融合蛋白可增强NK细胞活性、提高IFN-γ的产生和促进人淋巴母细胞的增殖。结论:转染pcDNA3.1(+)-pscIL-12质粒的CHO-K1细胞成功表达了具有良好生物学活性的pscIL-12。     

干扰素-γ水平影响系统性红斑狼疮小鼠体TLR9/MyD88/NF-κB p65信号通路的初步研究

目的 探究干扰素-γ(IFN-γ)水平对系统性红斑狼疮(SLE)小鼠体内Toll样受体9/髓样分化因子88/核因子κB亚基p65(TLR9/MyD88/NF-κB p65)信号通路的影响.方法 将30只SLE MRL/lpr小鼠随机分为模型组、空质粒组和IFN-γ siRNA组,空质粒组和IFN-γsiRNA组采用活体电转染技术分别转入空质粒、IFN-γsiRNA质粒,并鉴定转染后SLE小鼠外周血IFN-γγ的表达;另取10只C57BL/6小鼠作为正常组,ELISA检测IL-6、TNF-α和自身抗体[抗双链DNA(ds-DNA)抗体、抗组蛋白抗体(IgM)]水平,观察各组小鼠肾组织病理变化及肾功能情况[血清肌酐(SCr)、尿素氮(BUN)],Western blot检测肾组织中TLR9、MyD88、NF-κB p65蛋白表达.结果 与正常组比较,模型组血清IFN-γγ、 IL-6、TNF-α、抗ds-DNA抗体、抗IgM抗体、SCr、BUN、肾组织TLR9、MyD88、NF-κB p65磷酸化水平显著升高(P＜0.05);与模型组比较,IFN-γsiRNA组IFN-γγ、IL-6、TNF-α、抗ds-DNA抗体、抗IgM抗体、SCr、BUN、肾组织TLR9、MyD88、NF-κB p65磷酸化水平显著降低(P＜0.05);但空质粒组与模型组上述指标的比较,差异无统计学意义(P＞0.05).结论 转染IFN-γγsiRNA质粒后,可减轻SLE小鼠炎症反应与肾损伤,可能与抑制TLR9/MyD88/NF-κB p65信号通路有关.     

共表达不同水平的IL-12对于HBV DNA疫苗质粒免疫原性的影响

目的 在HBsAg DNA疫苗质粒中共表达IL-12佐剂分子,研究IL-12的表达水平对于HBV DNA疫苗质粒免疫原性的影响.方法 构建携带来源于中国地区C型HBV参照序列CHN-HBV07-C经密码子优化的preS2-S基因的DNA疫苗质粒pHBV,并将3个不同IL-12表达水平的佐剂分子表达盒序列分别克隆入该疫苗质粒中,通过瞬时转染293T细胞以检测重组质粒IL-12分子及乙肝表面抗原的表达情况.将不同IL-12表达水平的疫苗质粒免疫BALB/c雌性小鼠,IFN-γ的ELISPOT方法检测HBsAg抗原特异性的细胞免疫应答,化学发光定量ELISA法检测HBsAg特异的抗体水平.结果 成功构建3个不同IL-12表达水平的HBV DNA疫苗质粒,293T细胞转染结果显示:不携带IL-12分子表达盒的对照疫苗质粒pHBV的HBsAg表达水平可达70 ng/ml;低表达IL-12的疫苗质粒pHBV-12l的HBsAg表达水平为18 ng/ml;而高表达IL-12的重组疫苗质粒pHBV-12h的HBsAg表达水平仅为6 ng/ml.BALB/c小鼠的免疫结果表明:高表达IL-12分子的疫苗质粒pHBV-12h所诱导的细胞免疫及体液免疫水平相对于对照疫苗质粒pHBV均显著降低了.低表达IL-12分子的疫苗质粒pHBV-12l所诱导的抗体水平也显著降低了,但其细胞免疫应答水平却显著提高了.结论 在同一疫苗质粒中,高表达IL-12分子的质粒可能会影响到抗原蛋白的表达,而低表达IL-12分子的疫苗质粒却能增强细胞免疫应答.因此,平衡好佐剂分子及抗原蛋白的表达水平对于诱导高水平的免疫应答是个重要的因素.     

NBD多肽抑制HSP60诱导的小鼠骨髓树突状细胞激活

目的观察热休克蛋白60(HSP60)对小鼠骨髓树突状细胞(dendritic cell,DC)生物学活性的影响,并探讨核因子κB必需分子(NF-κB essential modulator,NEMO)结合的小分子多肽(NEMO binding domain,NBD)对DC活性的干预作用,为NBD多肽的临床应用提供理论依据。方法培养小鼠骨髓源性DC,分为对照组、HSP60组及NBD组,对照组在正常条件下培养,HSP60组加入终质量浓度为10μg/ml的HSP60,NBD组在加入NBD(50μmol/ml)4 h后给予10μg/ml的HSP60刺激,继续培养3 d。流式细胞术检测DC细胞表面CD80、CD86及MHC-Ⅱ分子的变化,ELISA法检测各组DC分泌肿瘤坏死因子-α(TNF-α)、干扰素-γ(IFN-γ)和白介素-12(IL-12)的质量浓度,免疫细胞化学检测DC核因子-κB(NF-κB)的表达,混合淋巴细胞培养检测T细胞增殖能力。结果 HSP60可促进DC高表达CD80、CD86及MHC-Ⅱ分子,促进Th1型细胞因子TNF-α、IFN-γ及IL-12释放、NF-κB高表达并易位于核内,并诱导T细胞增殖,NBD多肽可阻断HSP60的这些效应。结论 NBD多肽可抑制HSP60诱导的DC激活。     

IL-12基因修饰DC中SOCS1基因沉默对体外诱导特异性CTL的影响

利用重组腺病毒载体pAd CMV/V5-DEST-IL-12转染小鼠骨髓来源的树突状细胞(IL-12/DC),探讨SOCS1基因沉默IL-12/DC在体外诱导细胞毒性T淋巴细胞(CTL)的效能,及其免疫杀伤肺癌细胞株LLC的能力。采用重组腺病毒介导IL-12基因和SOCS1SiRNA基因共同修饰C57BL/6小鼠骨髓来源的DC,经反复冻融法提取LLC抗原,致敏基因修饰的DC;用ELISA法检测各组DC分泌IL-12和IL-10的水平,及各组DC刺激后的T细胞分泌IFN-γ的水平;MTT法检测DC刺激同源小鼠T细胞的增殖能力,微量细胞毒法检测CTL的活性并收集刺激后的T细胞,流式细胞术分析CD8+/CD4+比例和CD4+CD25+Treg的水平;统计学分析各组间的差异。SOCS1SiRNA和IL-12基因共同修饰能有效下调DC中SOCS1蛋白的表达并上调IL-12蛋白的表达;IL-12的分泌水平也明显高于SOCS1SiRNA或IL-12单基因转染组;基因共同修饰的DC表型更加成熟,能明显促进CTL的增殖和活化,减少Treg的生成;CTL分泌高水平的IFN-γ,产生对LLC特异性的细胞免疫。     

肾癌相关抗原G250的原核表达、纯化及抗原活性检测

目的 构建原核表达质粒pET-42a-hG250,表达并纯化肾癌相关抗原G250融合蛋白,并检测G250融合蛋白的抗原活性.方法 利用PCR从pGEM-T-G250质粒中扩增G250基因片段(112～1242 bp),测序正确后将其克隆至原核表达载体pET-42a中构建重组载体pET-42a-hG250.将其转化至大肠杆菌BL21(DE3)中,通过IPTG诱导G250蛋白的原核表达,随后将表达的融合蛋白进行纯化.经SDS-PAGE分析后,Western blot法检测纯化的蛋白,将纯化蛋白进一步包板后用ELISA对其抗原活性进行评价.结果 酶切和测序结果证实pET-42a-hG250原核表达载体构建成功;转化后可以成功诱导并纯化出大小与预期一致的G250融合蛋白;Western b1ot法和ELISA检测证实纯化的蛋白能与特异性的抗体发生反应,显示纯化后的G250融合蛋白具有良好的免疫原性.结论 成功构建了肾癌相关抗原G250基因的原核表达载体,纯化获得了G250融合蛋白,该蛋白具有良好的抗原活性.     

肾透明细胞癌中氧化应激蛋白的表达

目的:探讨人肾透明细胞癌细胞株RLC-310与人正常肾近曲小管上皮细胞株HK-2,肾癌及其癌旁组织中氧化应激蛋白表达的差异。方法:体外培养RLC-310和HK-2,采用PF-2D蛋白分级分离系统分离细胞总蛋白,选取差异蛋白组分进行毛细管LC-ESI-MS/MS分析,结合蛋白质数据库检索对差异蛋白进行鉴定,并对代表性氧化应激差异蛋白采用免疫组织化学方法进行验证。结果:两个细胞株经串联质谱分析共鉴定出12个氧化应激差异表达蛋白,分别是peroxiredox-in-1(PRX-1)、peroxiredoxin-6(PRX-6)、superoxide dismutase[Cu-Zn]SOD1、glutathione peroxidase 1、catalase、glutathionesynthetase、glutathione S-transferase Pi(GSTPi)、thioredoxin、热休克蛋白10(heat shock protein,HSP10)、HSP 60、HSP 70和HSP 90。其中PRX-6、HSP 60、GSTPi三种代表性差异蛋白在人肾透明细胞癌细胞株RLC-310和人正常肾近曲小管上皮细胞株HK-2中均有表达,前者的表达水平较后者显著升高(P<0.05),这三种蛋白在肾癌组织中表达也较癌旁组织显著升高(P<0.05)。结论:人肾透明细胞癌中存在抗氧化应激蛋白的差异表达,这些氧化应激蛋白的异常表达在阻止肾癌细胞氧化损伤中起一定作用。     

重组质粒pEGFP-N1/CpG-HBcAg(ISS)转染DC培养上清诱导HepG2株凋亡的研究

目的:探讨人类乙肝核心抗原重组质粒pEGFP-N1/CpG-HBcAg(ISS)转染人外周血单核细胞来源树突状细胞后,细胞培养上清诱导肝癌细胞株HepG2凋亡的作用及机制。方法:构建真核表达质粒pEGFP-N1/CpG-HBcAg(ISSa,c),将其转染人外周血来源DC,用培养上清诱导HepG2的凋亡。用流式细胞仪检测已转染DC表面CD80和CD86的表达,检测培养上清诱导HepG2凋亡的变化。用ELISA法检测转染后DC培养上清的IFN-γ、IL-2、IL-12、IL-4和IL-10的水平。结果:pEGFP-N1/CpG-HBcAg(ISSa)转染DC表面CD80和CD86的表达均有明显升高(P0.01)。转染后上清中Th1型细胞因子IFN-γ、IL-2和IL-12的表达增强(P0.01),Th2型细胞因子IL-4和IL-10的表达下降(P0.05),pEGFP-N1/CpG-HBcAg(ISSa)组培养上清对HepG2细胞具有促凋亡作用,随着培养时间延长,细胞凋亡率逐渐增加,HepG2细胞在诱导后24小时凋亡率达到最大,为18.4%。结论:重组质粒pEGFP-N1/CpG-HBcAg(ISSa)转染培养上清能明显促进肝癌细胞株HepG2的凋亡。     

人T-bet基因转染U937探讨T-bet对白血病细胞的影响

目的 探讨人T-bet基因在白血病细胞株U937中的表达及其对IFN-γ分泌的影响,寻求通过免疫调节改善白血病患者机体免疫状态的可能性.方法 采用电穿孔技术将重组人pIRES-eGFP-Tbet(pIRES-eGFP-hTbet)质粒转染U937细胞,RT-PCR检测转染前后U937细胞T-bet的mRNA水平;westen-blot检测表达的T-bet蛋白;ELISA检测其分泌IFN-γ的水平.试验中同时设立pIRES-eGFP质粒为对照.结果 电穿孔转染U937细胞后,在荧光显微镜下观察到带荧光的细胞(转染细胞),其荧光细胞阳性率80%左右,提示转染成功;转染T-bet的U937细胞,分别经RT-PCR及westen-blot检测到T-bet的mRNA和表达的蛋白,而未经转染或转染对照质粒pIRES-eGFP的细胞,均未见目的基因的转录和蛋白表达;T-bet转染细胞的培养上清中含有较高水平的IFN-γ,而转染前及对照质粒转染的细胞IFN-γ的分泌水平极低.结论 通过电穿孔方法 成功将人T-bet基因转染到白血病细胞株U937中,并检测到大量IFN-γ的产生.T-bet是免疫应答调节的重要转录因子,对其研究将有助于进一步探讨T-bet基因或其表达产物作为Th1应答的调节剂用于临床血液病治疗的可能性.     

乙型肝炎病毒C蛋白对NK细胞功能影响的体外研究

目的 研究乙型肝炎病毒C蛋白在NK细胞中的表达及其对NK细胞功能的影响.方法 用脂质体转染法将HBV C基因真核表达载体pHBI-CMV-HBC转入NK-92细胞,通过WesternBlot检测C基因在NK-92细胞中表达,用ELISA法检测NK细胞分泌IFN-γ水平,MTT法检测NK细胞对HepG2细胞的细胞毒作用.结果 Western Blot证实转染有pHBI-CMV-HBC的NK-92细胞能表达HBV C蛋白.转染了重组真核表达质粒的NK-92细胞IFN-γ水平均高于空质粒对照组和空白对照组(P<0.01).与两对照组相比,重组真核表达质粒转染组NK-92细胞对于HepG2细胞的细胞毒活性明显提高,差异具有统计学意义(P<0.01).结论 HBc基因瞬时高表达可影响NK-92细胞分泌IFN-γ和细胞毒功能.     

Ectopic expression of activated Stat6 induces the expression of Th2-specific cytokines and transcription factors in developing Th1 cells

Stat6 is critical for IL-4-mediated Th2 cell development, but its molecular mechanism remains unclear. Here we constructed Stat6:ER, a Stat6-estrogen receptor fusion protein that can be activated by 4-hydroxy-tamoxifen, independently of IL-4 and endogenous Stat6. Retrovirus-mediated introduction of Stat6:ER into developing Th1 cells induced Th2-specific cytokines and suppressed IFNgamma production in a 4-HT-dependent manner and in the absence of IL-4. It also induced GATA-3 and c-maf expression and downregulated IL-12Rbeta2 chain expression. Its decreased ability to induce the Th2 phenotype with progressing Th1 cell commitment correlated with a decreased induction of GATA-3 and c-maf. This study indicates that Stat6 functions upstream of GATA-3 and c-Maf to induce Th2 development.     

Interferon-γ and interleukin-4 regulate T cell interleukin-12 responsiveness through the differential modulation of high-affinity interleukin-12 receptor expression

Interferon-γ (IFN-γ) and interleukin-4 (IL-4) are mutually antagonistic cytokines that stimulate CD4⁺ T cells to develop into either Th1 or Th2 cells. One feature of Th2 differentiation in mice is the loss of IL-12-induced Jak2 and Stat4 activation, which is accompanied by the inability to produce IFN-γ in response to IL-12. In this report, we show that freshly isolated human T cells activated with phytohemagglutinin (PHA) in the presence of IL-4 exhibit a greatly diminished response to IL-12, whereas the IL-12 response of T cells activated with PHA plus IFN-γ is enhanced. Radiolabeled IL-12 binding studies demonstrate that the impairment of T cell IL-12 responsiveness by IL-4 is associated with the down-regulation of high-affinity IL-12 receptor expression. In contrast, the enhancement of IL-12 responsiveness by IFN-γ is associated with the up-regulation of high-affinity IL-12 receptor expression. Through the use of a newly synthesized neutralizing antibody to the low-affinity IL-12 receptor β subunit (IL-12Rβ), we show that neither IL-4 nor IFN-γ affect the expression of IL-12Rβ, which we determine to be one of at least two low-affinity subunits required for high-affinity IL-12 binding. These findings suggest that IL-4 and IFN-γ exert opposite effects on T cell IL-12 responsiveness by differentially modulating the expression of low-affinity IL-12 receptor subunits that are distinct from IL-12Rβ and required, together with IL-12Rβ, for high-affinity IL-12 binding and IL-12 responsiveness. This provides a basis for understanding the interplay between different cytokines at the level of cytokine receptor expression, and offers insight into one of the mechanisms governing Th1 and Th2 development.     

Interleukin-12 differentially regulates expression of IFN-gamma and interleukin-2 in human T lymphoblasts.

Interleukin-12 (IL-12) is known to upregulate expression of interferon-gamma (IFN-gamma) by activated T cells. However, the effects of IL-12 on production of other Th1-type cytokines are less well defined. In this study, we examined the effects of IL-12 on expression of several cytokines, including IFN-gamma, IL-2, tumor necrosis factor-alpha (TNF-alpha), and IL-10, by primary human CD3(+) T cells. Although purified resting T cells were largely nonresponsive to IL-12 stimulation, anti-CD3-activated T cell blasts were strongly responsive, as demonstrated by the ability of IL-12 to induce Stat4 DNA-binding activity. Restimulation of T lymphoblasts on immobilized anti-CD3 monoclonal antibodies (mAb) induced rapid expression of TNF-alpha mRNA and more gradual increases in mRNA levels for IL-2, IFN-gamma, and IL-10. IL-12 markedly upregulated expression of IFN-gamma and IL-10 but downregulated expression of IL-2 in a dose-dependent and time-dependent manner. The levels of IL-2 produced by IL-12-treated T cells correlated inversely with the levels of IL-10. Moreover, neutralization of IL-10 activity with anti-IL-10 antibodies normalized IL-2 production by IL-12-treated T cells, confirming that the inhibition of IL-2 production by IL-12 was IL-10 mediated. Thus, IL-12 amplified expression of IFN-gamma and IL-10 and, via its ability to upregulate production of IL-10, inhibited expression of IL-2. These findings demonstrate that IL-12 differentially regulates expression of the Th1-type lymphokines, IFN-gamma and IL-2, in T lymphoblasts.     

Adenoviral interleukin-12 gene transduction into human bronchial epithelial cells: up-regulation of pro-inflammatory cytokines and its prevention by corticosteroids

BACKGROUND: One of the potential effects of IL-12 is to restore Th1/Th2 balance. Therefore, we investigated the possibility of developing a system for local delivery of IL-12 into the airways by examining protein expression in a human bronchial epithelial cell line (BEAS-2B) after adenoviral IL-12 gene transduction. The effects of dexamethasone on the gene-modified cells were also examined. MEHODS: Adenoviral vectors AxCAegfp and Ax1CIhp40ip35 were used to transduce enhanced green fluorescence protein and IL-12 genes, respectively, into BEAS-2B cells. Wild-type and IL-12 gene-transduced BEAS-2B cells were then incubated with or without dexamethasone, and concentrations of IL-12, IFN-gamma, IL-6, IL-8, granulocyte macrophage-colony stimulating factor and chemokines (TARC and RANTES) in the supernatant were measured by ELISA. IL-12 receptor expression was analysed by flow cytometry and RT-PCR. RESULTS: The efficiency of transgene expression in BEAS-2B cells at a multiplicity of infection of 30 was approximately 80%. Gene-modified BEAS-2B cells produced biologically active IL-12, regardless of dexamethasone treatment. While IL-12 gene transduction led to increased production of IL-6 and IL-8 by BEAS-2B cells, expressions of these proteins were suppressed by dexamethasone. Addition of exogenous IL-12 failed to augment BEAS-2B cell IL-6 and IL-8 production, and IL-12 receptor expression by BEAS-2B cells was not detected. CONCLUSIONS: Our findings suggest that adenoviral IL-12 gene transduction may be effective in inducing IL-12 expression in the airways, and could be a potential approach in the management of bronchial asthma.     

Expression of cytokines and inducible nitric oxide synthase mRNA in the lungs of mice infected with Cryptococcus neoformans: effects of interleukin-12.

We have recently established a murine model of pulmonary and disseminated infection with a highly virulent strain of Cryptococcus neoformans and demonstrated that administration of interleukin-12 (IL-12) protected the animals against infection. In this study, we extended these studies by investigating the host defense mechanisms. In particular, we examined the expression of mRNA for helper T-cell 1 (Th1) cytokines (IL-2, lymphotoxin, and gamma interferon [IFN-gamma]), Th2 cytokines (IL-4, -6, and -10), macrophage-derived cytokines (tumor necrosis factor alpha [TNF-alpha], IL-1beta, transforming growth factor beta [TGF-beta, IL-12p40, and IFN-gamma-inducing factor [IGIF]), and inducible nitric oxide synthase (iNOS) in the lungs on days 1, 3, 7, and 14 after infection and following treatment with IL-12. There was little or no expression of mRNAs for Th1 cytokines, TNF-alpha, IL-12p40, IGIF, and iNOS in the infected mice, but expression increased markedly after treatment with IL-12. In contrast, the mRNAs for Th2 cytokines, IL-1beta, and TGF-beta were detected at considerable levels during the early stages of infection, and, interestingly, expression was not suppressed by IL-12 but rather augmented, particularly during the late stage. Similar results were also obtained for IFN-gamma, IL-4, IL-10, and TNF-alpha measured in the lung homogenates by enzyme-linked immunosorbent assay. These results suggest that the predominance of expression of Th2 cytokines and TGF-beta over Th1 cytokines, TNF-alpha, IL-12p40, IGIF, and iNOS is associated with severe lethal infection in mice and that administration of IL-12 protects infected animals by stimulating Th1 cytokines.     

Influence of allergen-specific immunotherapy on IL-4-dependent IL-12 production by monocytes

Allergen-specific immunotherapy (AIT) is an effective method of allergy treatment. Reduction of allergy symptoms followed by AIT presumably depends on modification of cytokine production, especially of IFN-gamma and/or IL-4. Previously, we found that lower IL-12 production by allergic monocytes than in healthy control, could depend on higher IL-4 receptor alpha-chain (CD124) expression. Since IFN-gamma production is stimulated by IL-12, which in turn is down-regulated by IL-4, the aim of study was to analyze the influence of AIT on the network of these cytokines. Moreover, we estimated the possible role of CD124 in that process. Patients (n=16) with grass pollen allergy were subjected to AIT with Allergovit for 5 to 6 weeks. The clinical examination and blood analyses were performed before and after AIT. Clinical improvement in course of AIT was rather weak, however, we found significant increase of mean IFN-gamma production by PBMC. Although the increase of mean IL-12 production by monocytes following AIT was non-significant, we observed statistically significant decrease of monocyte sensitivity to IL-4 suppressed IL-12 production. Flow cytometry analysis revealed significant decrease of CD124 expression on monocytes after AIT. Despite unchanged mean IL-4 level the decrease of CD124 expression after AIT could explain the decreased monocyte sensitivity to IL-4 and its role in further IL-12 and IFN-gamma tuning.     

The role of interleukin-10 in the differential expression of interleukin-12p70 and its beta2 receptor on patients with active or treated paracoccidioidomycosis and healthy infected subjects

Paracoccidioidomycosis patients present an antigen-specific Th1 immunosuppression. To better understand this phenomenon, we evaluated the interleukin (IL)-12 pathway by measuring IL-12p70 production and CD3+ T cell expression of the IL-12 receptor (IL-12R)beta1/beta2 chains, induced with the main fungus antigen (gp43) and a control antigen, from Candida albicans (CMA). We showed that gp43-induced IL-12p70 production and IL-12Rbeta2 expression were significantly decreased in acute and chronic patients as compared to healthy subjects cured from PCM or healthy infected subjects from endemic areas. Interestingly, the healthy infected subjects had higher gp43-induced IL-12p70 production and beta2 expression than the cured subjects. The addition of a neutralizing anti-IL-10 antibody to the cultures increased IL-12p70 levels and beta2 expression in acute and chronic patients to levels observed in cured subjects. Conversely, addition of the cytokine IL-10 strongly inhibited both parameters in the latter group. In conclusion, we have shown that paracoccidioidomycosis-related Th1 immunosuppression is associated with down-modulation of the IL-12 pathway, that IL-10 may participate in this process, and that patients cured from paracoccidioidomycosis may not fully recover their immune responsiveness.     

Differential requirement of CD28 for IL-12 receptor expression and function in CD4(+) and CD8(+) T cells

IL-12 is a potent inducer of IFN-gamma production and Th1 responses. Co-stimulation mediated by B7 has been shown to synergize with IL-12 for optimal IFN-gamma production and proliferation in vitro. In this study, we examined the requirement of CD28/B7 interactions for optimal induction of IL-12 receptor(R) beta1 and beta2 expression and IFN-gamma. IL-12-induced IFN-gamma production and STAT4 nuclear translocation were markedly reduced in CD28(-/-) splenocytes compared to that of wild-type (WT) splenocytes. Analysis of IL-12R expression revealed that IL-12 induced similar levels of IL-12R beta2 mRNA expression in WT and CD28(-/-) cells. In contrast, IL-12R beta1 expression was impaired in CD28(-/-) cells, indicating that expression of IL-12R beta1 and beta2 is differentially regulated by CD28. CD28(-/-) CD4(+) but not CD8(+) cells exhibited a defect in IL-12Rbeta1 expression that was associated with a marked decrease in IL-12 binding as well as IL-12-induced IFN-gamma production. IL-2 could restore IL-12R expression to CD28(-/-) CD4(+) cells, however, this occurred independently of IL-2-induced proliferation. Thus, these findings identify distinct requirements for CD28 in the capacity of CD4(+) and CD8(+) cells to respond maximally to IL-12.     

白细胞介素-24基因重组表达载体的构建及原核表达

目的：构建人白细胞介素-24(hIL-24)基因的表达载体并在大肠杆菌中表达。方法：用PCR从质粒TRAP-IL-24中扩增hIL-24 cDNA片段，并将该片段插入pGEX-KG原核表达载体中，实现插入基因的融合表达。用SDS-PAGE和Western blot对表达产物进行鉴定。采用MTT法检测GST-IL-24融合蛋白的生物学活性。结果：酶切结果证实，成功地构建了pGEX-KG-IL-24原核表达载体，并在大肠杆菌中获得稳定的表达，表达产物的相对分子质量(M1)同预期值相-致。GST-IL-24融合蛋白能够抑制THP-1细胞的生长。结论：成功地构建了重组表达载体pGEx-KG-IL-24，并在E．coli BL21中表达了具有生物学活性的GST-IL-24融合蛋白，为下-步研究人IL-24的功能奠定了基础。     

IL-12双亚基共表达载体的构建及其在人骨髓间充质干细胞中的表达

目的构建人IL-12（hIL-12）p40和p35双亚基真核共表达载体并转染人骨髓间充质干细胞（hMSC）。方法根据hIL-12p40和p35亚基全长cDNA序列分别设计合成引物行PCR扩增，将扩增所得p40和p35片段采用overlap PCR法拼接，获得的rhIL-12融合基因与pGEM—TEasy质粒连接，将鉴定正确的pGEM—T／rhIL-12重组质粒克隆至pcDNA3．1（＋）真核表达质粒中，构建pcDNA3．1（＋）／rhIL-12真核表达载体，并进行测序鉴定。将鉴定正确的pcDNA3．1（＋）／rhIL-12经脂质体介导转染hMSC，同时以转染pcDNA3．1（＋）空质粒作为对照组，在倒置显微镜下观察细胞生长形态；在转染后第4天采用蛋白质印迹法检测细胞培养上清液中rhIL-12融合基因的表达；另分别在转染后第2、4、6、8、10、12、14天，采用ELISA方法检测细胞培养上清液中rhIL-12融合基因的表达水平。结果PCR扩增结果显示特异性扩增出p40（1000bp）、p35（600bp）、rhIL-12（1600bp）片段，均与预期DNA表达片段大小一致。pcDNA3．1（＋）／rhIL-12测序显示克隆的rhlL-12基因序列与报告序列完全相同。倒置显微镜下观察，可见转染pcDNA3．1（＋）／rhIL-12的hMSC生长形态和生长速度与对照组hMSC相比均无明显差异。蛋白质印迹和ELISA检测显示，转染pcDNA3．1（＋）／rhIL-12的hMSC培养上清液中可见rhIL-12融合蛋白的持续表达；而对照组中均未检测到rhIL-12融合蛋白表达。结论成功构建了hIL-12p40和p35双亚基真核共表达载体pcDNA3．1（＋）／rhIL-12，为利用hIL-12进行非病毒载体抗肿瘤基因治疗奠定了基础。