肥胖对非致死性肺炎模型小鼠脾脏、外周血T淋巴细胞亚群的影响

目的探讨肥胖在感染肺炎时对机体免疫功能的调节是否与脾脏和外周血中T淋巴细胞亚群的变化有关。方法将常规非肥胖小鼠分为Ⅰ、Ⅱ组,将高脂诱导小鼠分为Ⅲ、Ⅳ组,Ⅰ、Ⅲ组滴鼻40μl PBS溶液,Ⅱ、Ⅳ组滴鼻40μl含5.9×10~(10)CFU大肠杆菌的菌液,于感染前(0 h)和感染后12 h、24 h、72 h检测各小组脾脏和外周血中的T淋巴细胞亚群。结果在感染后12 h、72 h,Ⅳ组脾脏的CD3~+细胞比例较Ⅲ组显著下降(P0.05),Ⅱ组CD4+细胞比例较Ⅰ组显著升高(P0.05);在感染后24 h、72 h,Ⅳ组CD4~+细胞比例较Ⅲ组显著下降(P0.05)。在感染后24 h、72 h,Ⅱ组CD8~+细胞比例组较Ⅰ组显著下降(P0.05);在感染后12 h、24 h、72 h,Ⅳ组CD8~+细胞比例较Ⅲ组显著下降(P0.05)。在感染后12 h、24 h、72 h,Ⅱ组CD4~+/CD8~+比值较Ⅰ组显著升高(P0.05)。各组外周血中的CD3~+细胞比例,在感染后12 h、72 h,Ⅳ组显著高于Ⅱ组(P0.05);各组外周血中的CD4+细胞比例,在感染前(0 h),Ⅲ组显著高于Ⅰ组,Ⅳ组显著高于Ⅱ组(P0.05)。结论感染非致死性肺炎后,肥胖机体能动员脾脏更多的T淋巴细胞释放入血,加强了机体的细胞免疫功能,有利于抵抗外来病原体的入侵。     

卵巢切除对成年小鼠免疫系统淋巴细胞亚群组成的影响

目的: 研究卵巢切除对成年小鼠胸腺和外周淋巴器官淋巴细胞亚群组成的影响。方法: 用双色免疫荧光结合流式细胞仪, 检测成年小鼠双侧卵巢切除 14d后, 胸腺、脾脏和腹腔淋巴细胞亚群的比例。结果: 与伪手术组相比较, 卵巢切除的成年小鼠胸腺CD4 CD8 T细胞的比率显著升高(P<0. 05), CD4- CD8- T细胞和CD4 CD8- T细胞的比率显著降低(P<0. 05); 脾脏和淋巴结中CD4 CD8- T细胞的比率显著降低(P<0. 05)。结论: 成年小鼠切除卵巢后, 可明显影响免疫系统淋巴细胞亚群的组成; 对于胸腺T细胞的发育及向外周输出也有一定的影响。     

趋化因子受体CXCR3与其配体在小鼠暴发性肝炎发病中免疫学机制研究

目的 探讨趋化因子受体CXCR3与其配体(CXCL9/Mig,CXCL10/IP-10)在小鼠暴发性肝炎淋巴细胞迁移和急性肝衰竭中的作用.方法 6～8周龄雌性BALB/cJ小鼠腹腔注射100 PFU 3型鼠肝炎病毒(MHV-3),采用流式细胞术检测感染MHV-3后的BALB/cJ小鼠肝脏、脾脏和外周血T细胞和NK细胞的比例、数量以及其表面趋化因子受体CXCR3的表达频率.实时定量PCR技术检测感染MHV-3后的BALB/cJ小鼠肝内趋化因子CXCL9和CXCL10 mRNA的表达水平.Transwell细胞迁移试验评估病毒感染的肝细胞及CXCL10对脾脏淋巴细胞的趋化作用.结果 BALB/cJ小鼠感染MHV-3后,肝脏T细胞和NK细胞的数量及CXCR3的表达频率均显著增加,然而在脾脏和外周血均显著减少.实时定量PCR检测证实,感染MHV-3 48 h后,肝内趋化因子CXCL9和CXCL10 mRNA的表达比感染前分别上升了15.6和98.8倍.体外Transwell试验表明,病毒感染的肝细胞及重组CXCL10/IP-10蛋白对脾脏T细胞和NK细胞具有明显的趋化作用,并且这种趋化作用能被抗-CXCL10抗体显著阻断.结论 趋化因子受体CXCR3与其配体(CXCL9和CXCL10),尤其是CXCL10的相互作用在小鼠暴发性肝炎肝内淋巴细胞的募集及随后的坏死性炎症和急性肝衰竭中可能发挥着重要作用.

Abstract：

Objective To investigate the role of the chemokine receptor CXCR3 and its ligands in the migration of lymphocytes and acute hepatic failure. Methods BALB/cJ mice (6-8 weeks, female) were intraperitoneally injected with 100 PFU mouse hepatitis virus-3(MHV-3). The proportions and numbers of T cells and NK cells in liver, spleen, and blood as well as the expression of CXCR3 in T cells, and NK cells post MHV-3 infection was analyzed by flow cytometry. The hepatic mRNA level of the CXCR3-associated chemokines(CXCL9 and CXCL10) was detected by real-time PCR. A transwell migration assay was used to assess the chemotactic effect of MHV-3-infected hepatocytes and CXCL10 on the splenic lymphocytes. Results Following MHV-3 infection, the number of hepatic NK cells and T cells and the frequencies of hepatic NK cells and T cells expressing CXCR3 increased markedly; however, in the spleen and peripheral blood, they both decreased significantly. Moreover, the hepatic mRNAs levels of CXCL9 and CXCL10 were significantly elevated post infection. The transwell migration assay demonstrated that MHV-3-infected hepatocytes have the capacity to attract and recruit the splenic NK cells and T cells, and CXCL10 plays a key role in lymphocyte mobilization from the spleen. Conclusion Interactions between CXCR3 and its ligands (CXCL9 and CXCL10),especially CXCL10 may play a key role in the recruitment of intrahepatic lymphocytes and subsequent necroinflammation and acute hepatic failure in MHV-3 infection.     

调节性T细胞在3型鼠肝炎病毒诱导的小鼠暴发型肝炎模型中作用的初步探讨

目的 检测调节性T细胞(Tr)在3型鼠肝炎病毒(MHV-3)诱导的小鼠暴发型肝炎模型中的比例变化及细胞因子表达,初步探讨Tr在该疾病模型中的作用.方法 通过腹腔注射MHV-3感染BALB/cJ小鼠诱导暴发型肝炎,观察小鼠的生存时间,检测血清谷丙转氨酶(ALT)、谷草转氨酶(AST)水平,利用苏木精-伊红(HE)染色法检测肝脏病理学改变,分离感染不同时间点外周血、脾脏以及肝脏中的淋巴细胞,利用流式细胞术来检测Tr的比例以及细胞因子IL-10表达水平.结果 BALB/cJ小鼠感染MHV-3后,全部在3～6d内死亡,血清ALT、AST水平随着感染时间延长逐渐升高,HE染色显示肝脏组织炎症及坏死程度逐渐加重,流式细胞术检测发现随着感染时间延长,小鼠肝脏中的Tr的比例明显升高.同时肝脏Tr分泌细胞因子1L-10的比例以及肝脏组织IL-10的mRNA水平逐渐升高.结论 MHV-3诱导的小鼠暴发型肝炎模型中Tr在肝脏中的比例和功能显著升高,这种代偿性升高提示Tr可能发挥调节机体过度免疫反应的功能.     

丙型肝炎患者外周血淋巴细胞亚群变化特点

目的观察丙型肝炎患者外周血淋巴细胞亚群变化特点。方法对219例丙型肝炎患者和66例健康对照者分别采用流式细胞术(FCM)检测外周血CD45+淋巴细胞,T淋巴细胞(CD45+CD3+、CD45+CD3+CD4+、CD45+CD3+CD8+),B淋巴细胞(CD45+CD3-CD19+),NK细胞(CD45+CD3-CD16+56+)百分比和细胞绝对计数。结果在丙型肝炎病毒(HCV)慢性感染到肝硬化失代偿过程中,淋巴细胞亚群绝对计数出现逐渐下降趋势。慢性丙型肝炎组较健康对照组CD4+T细胞、CD8+T细胞、NK细胞绝对计数明显降低(P0.05)。丙型肝炎肝硬化在早期组和失代偿期组淋巴细胞各亚群计数均较慢性丙型肝炎组明显降低(P0.01),而失代偿期组明显低于早期组(P0.01)。B淋巴细胞百分比以及CD4/CD8比值在慢性感染到肝硬化失代偿过程中出现升高趋势,并在丙型肝炎肝硬化早期和失代偿期时变化明显(P0.01,P0.05),NK淋巴细胞百分比出现明显降低趋势(P0.01)。结论 HCV感染慢性化至肝硬化早期和失代偿期的过程中,外周血CD8+T细胞、CD4+T细胞、NK细胞减少;B细胞百分比、CD4/CD8比值升高。     

芪芍五味子复方制剂对病毒性心肌炎小鼠免疫调节机制的研究

目的研究黄芪、赤芍、五味子组成的芪芍五味子复方制剂调节病毒性心肌炎(viral myocarditis,VMC)小鼠外周血T淋巴细胞亚群和细胞因子表达的机制。方法 Balb/c小鼠随机分为正常对照组、病毒对照组、中药高、中、低剂量组及VitC和病毒唑联用组。小鼠接种柯萨奇病毒B3(CVB3)建立VMC模型,流式细胞仪检测外周血CD4(+Th)和CD8(+Ts)淋巴细胞亚群数目及比值,ELISA检测IFN-γ、IL-4水平,心肌作组织病理学检查。结果与正常小鼠比较,病毒对照组小鼠外周血CD4+和CD8+淋巴细胞亚群数目下降,CD4+/CD8+下降,血清IFN-γ水平升高,IL-4水平降低(P0.05),中药治疗组小鼠淋巴细胞亚群数目及CD4+/CD8+均高于病毒对照组(P0.05),IFN-γ水平高于病毒对照组及VitC和病毒唑联用组(P0.05),同时小鼠心肌炎症性病理变化明显减轻。结论芪芍五味子复方制剂能调节外周血T淋巴细胞数目及比值,诱生Th1型细胞因子IFN-γ减轻CVB3感染小鼠心肌损伤,起到保护作用。     

细粒棘球绦虫重组BCG-Eg95疫苗诱导小鼠脾细胞亚群变化的研究

目的 探讨细粒棘球绦虫重组BCG-Eg95疫苗免疫和Eg原头节攻击后小鼠脾CD4 和CD8 T淋巴细胞亚群的变化.方法 将细粒棘球绦虫重组BCG-Eg95疫苗采用皮下注射、鼻腔内接种、口服灌胃和肌肉注射4种途径分别免疫Balb/c鼠,免疫后8周用Eg原头节进行攻击感染,感染后18周杀鼠取脾,分离脾细胞,流式细胞仪检测脾CD4 和CD8 T淋巴细胞亚群的百分比,同时设有BCG和PBS对照.结果 疫苗接种组的脾CD4 和CD8 T细胞亚群显著增加,口服接种组和肌肉注射组的CD4 T细胞亚群和CD4 /CD8 亚群比值显著高于皮下注射组和鼻腔内接种组.结论 CD4 T细胞亚群可能与细粒棘球绦虫重组BCG-Eg95疫苗诱导的小鼠抗Eg原头节攻击感染的保护力有关,疫苗口服接种和肌肉注射是两种较好的免疫途径.     

Graves病患者131I治疗前后CD4+CD25+ Foxp3+调节性T细胞的变化

目的:通过对Graves病患者131I治疗前后外周血各淋巴细胞亚群和CD4+CD25+ Foxp3+调节性T细胞含量以及相关基因Foxp3mRNA表达水平的测定,探讨131I治疗方法是否可以通过改变调节性T细胞的含量从而改善Graves病患者的免疫功能异常。方法:采集30例Graves病患者131I治疗前及治疗后1个月的外周血,流式细胞仪检测外周血CD3+、CD3+CD4+、CD3+CD8+、CD3-CD19+、CD3-CD16+CD56+淋巴细胞亚群及CD4+CD25+ Foxp3+调节性T细胞的百分率,Real-TimePCR检测外周血单个核细胞Foxp3mRNA的表达水平。结果:和治疗前相比,Graves病患者131I治疗1个月后外周血CD3+CD4+T细胞和CD3-CD19+B细胞百分率都明显减少(P<0.05),CD3-CD16+CD56+NK细胞百分率明显增加(P<0.05),CD3-CD8+T细胞、CD4+CD25+ Foxp3+调节性T细胞百分率和Foxp3mRNA的表达水平无明显变化。结论:131I不能通过增加调节性T细胞的含量而改善Graves病患者的免疫耐受障碍,但可以通过减少CD4+T和B淋巴细胞的含量和增加NK细胞的含量来控制过度的免疫应答。     

羧胺三唑增强小鼠脾脏淋巴细胞促进结肠癌细胞系MC38和C26凋亡

目的探讨羧胺三唑(CAI)直接或通过小鼠脾脏淋巴细胞间接对小鼠结肠癌细胞系(MC38和C26)存活和凋亡的影响。方法体外培养结肠癌细胞系MC38和C26细胞,分离小鼠脾脏淋巴细胞,MC38和C26细胞分别与小鼠脾脏淋巴细胞共培养,不同浓度CAI处理细胞。CCK-8法检测细胞存活,流式细胞测量术检测细胞凋亡以及小鼠脾脏淋巴细胞中CD4~+CD3~+ T细胞和CD8~+CD3~+ T细胞的比例。结果不同浓度CAI处理MC38和C26细胞后,活细胞数目减少(P0.05、P0.01和P0.001),凋亡率升高(P0.01和P0.001);MC38和C26细胞分别与小鼠脾脏淋巴细胞共培养48 h后,MC38和C26细胞数目减少(P0.001),凋亡率升高(P0.001);不同浓度CAI处理小鼠脾脏淋巴细胞共培养条件下的MC38和C26细胞48 h,与单独小鼠脾脏淋巴细胞处理相比,MC38和C26细胞数目进一步减少(P0.001),凋亡率进一步升高(P0.05和P0.001);不同浓度CAI处理小鼠脾脏淋巴细胞48 h后,小鼠脾脏淋巴细胞中CD4~+CD3~+ T细胞和CD8~+CD3~+ T细胞的比例显著升高(P0.05和P0.01)。结论 CAI抑制MC38和C26细胞存活、促进细胞凋亡,并可能通过升高小鼠脾脏淋巴细胞中CD4~+CD3~+ T细胞和CD8~+CD3~+ T细胞的比例增强小鼠脾脏淋巴细胞抑制MC38和C26细胞存活、促进细胞凋亡。     

哮喘患儿外周血CD3~+TCRvα24~+NKT细胞亚群分析

目的比较支气管哮喘急性发作期患儿和正常小儿外周血CD3+TCRvα24+NKT细胞频率;CD4+、CD8+、CD4-CD8-(DN)3个亚群比例;各亚群细胞胞内IL-4、IFN-γ水平及其表面活化分子CD69的表达情况。探讨NKT细胞在哮喘发作过程中的作用和机制。方法收集12例哮喘急性发作期患儿和10例健康小儿外周血,分离其中单个核细胞(PBMCs),对其表面分子CD3、TCRvα24、CD4、CD8、CD69及胞内分子IL-4、IFN-γ进行染色,流式细胞仪分析检测。结果哮喘患儿和健康小儿外周血CD3+TCRvα24+NKT细胞频率分别为0.42%、0.32%。哮喘组CD4+、CD8+、DN 3个亚群比例分别为:71.60%、14.90%、12.55%,正常对照组为:63.00%、13.12%、22.78%。哮喘患儿较正常小儿外周血CD4+NKT细胞比例上升,而DN NKT比例下降。3个亚群的NKT细胞均检测到了CD69、IL-4和IFN-γ的表达。总体而言,CD4+亚群和DN亚群胞内IL-4、IFN-γ水平较CD8+亚群高,DN NKT表面CD69表达高于其它2个亚群。但各亚群CD3+TCRvα24+NKT细胞CD69、IL-4和IFN-γ水平在哮喘组及正常对照组中未检测出明显差异。结论哮喘患儿急性发作期外周血CD3+TCRvα24+NKT细胞CD4+亚群频率上升,DN亚群频率下降。NKT细胞亚群比例的改变可能参与或介导了哮喘患儿急性期气道炎症反应。     

mfgl2基因反义质粒对小鼠暴发型肝炎病程的干预作用

目的研究mfgl2反义质粒对暴发型肝炎小鼠体内mfgl2表达的改变,以及对小鼠暴发型肝炎病情发展的影响。方法为了建立一个有效的体内基因转移系统,分别于感染前1 d和当天尾静脉高压注射LacZ质粒,第1天收集小鼠肝脏标本,并做X-gal染色观察质粒在肝脏的转染效率;用同样的方法将mfgl2反义质粒转入MHV-3感染的Balb/cJ小鼠肝脏,对照组用空载体代替。观察两组动物生存率,并于感染后第2天收集肝脏标本,HE染色观察肝脏病理组织学改变,免疫组化方法和RT-PCR方法检测mfgl2 mRNA和蛋白的表达水平。结果尾静脉高压注射可以使得目的基因在小鼠肝脏达到20%的转染效率。基因治疗组小鼠于感染后第2天mfgl2 mRNA和蛋白表达均明显下降。MHV-3感染后,对照组小鼠3 d内全部死亡,而基因治疗组33%的小鼠存活10 d以上。显微镜观察基因治疗组小鼠肝组织坏死轻微,而对照组肝组织有大片坏死。结论mfgl2反义质粒可以明显抑制mfgl2基因的表达,并且显著提高暴发型肝炎小鼠的生存率。     

Liver TCRγδ(+) CD3(+) CD4(-) CD8(-) T cells contribute to murine hepatitis virus strain 3-induced hepatic injury through a TNF-α-dependent pathway

The mechanisms of each subset of immune cells contributing to the pathogenesis of viral hepatitis remain incompletely understood. In this study, we examined the role of liver CD4(-) CD8(-) (double negative, DN) T cells during murine hepatitis virus strain 3 (MHV-3)-induced hepatitis in C3H/HeJ mice. We demonstrate that predominant population of DN T cells in the liver of healthy or MHV-3-infected mice express TCRγδ(+). The proportion of TCRγδ(+) DN T cells in liver CD3(+) T cells was markedly increased after MHV-3 infection. Adoptive transfer of TCRγδ(+) DN T cells led to dramatically decreased survival in MHV-3-infected mice, accompanied by deteriorated histopathology and elevated ALT and AST levels. It was found that these cells were hyperactivated after MHV-3 infection with a production of TNF-α, IFN-γ, IL-2 and IL-17A. Highly activated liver TCRγδ(+) DN T cells were cytotoxic to MHV-3-infected hepatocytes in vitro and this effect did not require cell-cell contact. Moreover, the cytotoxic effect of liver TCRγδ(+) DN T cells against hepatocytes involves TNF-α pathway, but not IL-17A or IFN-γ. These results indicate that liver TCRγδ(+) DN T cells play a critical role in the liver injury in MHV-3-induced hepatitis, via a TNF-α dependent pathway.     

Modulation of CD4 co-receptor limits spontaneous autoimmunity when high-affinity transgenic TCR specific for self-antigen is expressed on a genetically resistant background

Myelin proteolipid protein (PLP) 139-151 is an immunodominant peptide that induces experimental autoimmune encephalomyelitis (EAE) in H-2(s) SJL/J mice. While PLP 139-151-specific TCR transgenic (tg) 4E3 mice develop fulminant spontaneous disease on the susceptible SJL/J background, spontaneous EAE is dramatically reduced on the H-2(s) congenic B10.S background. On this resistant background, we observed a high frequency of positively selected tg CD4-CD8- (DN) thymocytes and peripheral DN tg T cells. Splenic DN tg T cells responded to anti-CD3 stimulation similarly to CD4+ cells, but proliferative and cytokine responses to PLP 139-151 were blunted, implying that CD4 co-receptor down-regulation modulated T cell responses to the self-antigen in vitro. Adoptive transfer of tg DN CD3hi cells into RAG-deficient wild-type (WT) recipients induced EAE less efficiently than transfer of CD4+ T tg cells indicating the blunted responses of DN tg T cells to self-antigen in vivo. The frequency of tg DN T cells was irrespective of thymic expression of the autoantigen. These data implicate that down-regulation of CD4 co-receptor in the thymus, which is independent from the expression of thymic autoantigen, results in a blunted response to the autoantigen in the periphery and limits the incidence of spontaneous autoimmunity in genetically resistant mice bearing a large autoreactive tg T cell repertoire.     

A Th1 cell line (3E9.1) from resistant A/J mice inhibits induction of macrophage procoagulant activity in vitro and protects against MHV-3 mortality in vivo.

Induction of immune coagulants has been implicated in the pathogenesis of murine hepatitis virus strain 3 (MHV-3)-induced fulminant hepatic necrosis. Previous work from our laboratory has shown that the induction of procoagulant activity (PCA) correlates with the resistance/susceptibility to disease in inbred and recombinant inbred (RI) strains of mice. Macrophages from susceptible, but not resistant, strains of mice expressed increased levels of PCA in response to MHV-3 stimulation. T lymphocytes, however, had a marked regulatory role in the final expression of macrophage PCA. CD3+ CD4+ CD8- lymphocytes from RI H-2 compatible susceptible mice were able to instruct macrophages from susceptible mice to express significantly augmented levels of PCA, whereas CD3+ lymphocytes from RI H-2 compatible MHV-3-immunized resistant mice were able to suppress induction of PCA. In this present study, T-cell lines were derived from draining popliteal lymph nodes from resistant A/J mice, which had been immunized with MHV-3. All T-cell lines showed marked proliferation to MHV-3 and MHV-JHM which was major histocompatibility complex (MHC) restricted. All cell lines were CD3+, four of these were CD4+ and one was CD8+. All of the CD4+ cell lines produced IL-2 and two produced interferon-gamma (IFN-gamma), consistent with the Th1 cytokine profile. One cell line (3E9.1) was able to inhibit the induction of macrophage PCA through production of a soluble factor although cell-to-cell contact could not be excluded. This CD4+ T-cell line conferred protection to infected and susceptible AXB8 mice. These results demonstrate that the existence of a Th1 subpopulation of cells with a regulatory effect on macrophage PCA induction in MHV-3-infected mice contributes to the resistance of the A/J strain of mice to MHV-3 infection.     

Mouse hepatitis viral infection induces an extrathymic differentiation of the specific intrahepatic alpha beta-TCRintermediate LFA-1high T-cell population.

Mouse hepatitis virus type 3 (MHV3), a coronavirus, is an excellent model for the study of thymic and extrathymic T-cell subpopulation disorders induced during viral hepatitis. It was recently reported that, in addition to the intrathymic T-cell differentiation pathway, an extrathymic differentiation pathway of alpha beta-T-cell receptor (TCR) T lymphocytes exists in the liver, and becomes important under pathological situations such as autoimmune diseases, malignancies or hepatic bacterial infections. In the present study, we compared the phenotypes of resident hepatic, splenic or thymic T-cell subpopulations during the acute viral hepatitis induced by HMV3 in susceptible C57BL/6 mice. The number of liver-resident mononuclear cells (MNC) increased during the viral infection, while cellularity decreased. Single positive (SP) CD4+ cells strongly increased in both the liver and thymus, while double positive (DP) (CD4+ CD8+) cells, present in the liver and thymus of mock-infected mice, decreased in C57BL/6 mice during the viral infection. A shift of alpha beta-TCRintermediate T cells toward alpha beta-TCRhigh was evidenced in the liver and thymus of infected mice, but not in the spleen. The few alpha beta-TCRint double negative (DN) (CD4-CD8-) cells also decreased following viral infection. alpha beta-TCRint or high lymphocytes expressing high levels of leucocyte function antigen-1 (LFA-1) increased in the liver of MHV3-infected mice. In addition, liver-resident T cells expressed strongly the CD44 (Pgp-1) activation marker, suggesting that they were either activated or antigen experienced during the viral infection. No significant change in T-cell subpopulations was detected in the spleen, suggesting that MHV3 infection could induce an early in situ differentiation of resident hepatic T cells rather than a recruitment of lymphocytes from peripheral lymphoid organs.     

Murine coronavirus spike glycoprotein mediates degree of viral spread,inflammation, and virus-induced immunopathology in the central nervous system

The mouse hepatitis virus (MHV) spike glycoprotein is a major determinant of neurovirulence. We investigated how alterations in spike affect neurovirulence using two isogenic recombinant viruses differing exclusively in spike. S(4)R, containing the MHV-4 spike gene, is dramatically more neurovirulent than S(A59)R, containing the MHV-A59 spike gene (J. J. Phillips, M. M. Chua, E. Lavi, and S. R. Weiss, 1999, J. Virol. 73, 7752-7760). We examined the contribution of differences in cellular tropism, viral spread, and the immune response to infection to the differential neurovirulence of S(4)R and S(A59)R. MHV-4 spike-mediated neurovirulence was associated with extensive viral spread in the brain in both neurons and astrocytes. Infection of primary hippocampal neuron cultures demonstrated that S(4)R spread more rapidly than S(A59)R and suggested that spread may occur between cells in close physical contact. In addition, S(4)R infection induced a massive influx of lymphocytes into the brain, a higher percentage of CD8(+) T cells, and a higher frequency of MHV-specific CD8(+) T cells relative S(A59)R infection. Despite this robust and viral-specific immune response to S(4)R infection, infection of RAG1-/- mice suggested that immune-mediated pathology also contributes to the high neurovirulence of S(4)R.     

Estrogen Blocks Early T Cell Development in the Thymus

PROBLEM: Pregnancy and estrogen are known to suppress B lymphopoiesis as well as lead to thymic involution in the mouse. Additionally, estrogen deficiency by oophorectomy reportedly causes a selective increase in the B220+ B cells in the murine bone marrow. The purpose of this study was to determine if estrogens played a regulatory role in T cell development. METHODS: The first experimental group consisted of 5–6-week-old Balb/c mice that received subcutaneous pellets of placebo, estriol, estradiol, or progesterone. The thymus glands were examined 2–4 weeks after treatment. The second group consisted of 6-week-old Balb/c mice who underwent either bilateral oophorectomy or a sham procedure. Two weeks after the surgery, extensive phenotypic characterization of the thymus and spleen cells was performed by flow cytometry using monoclonal antibodies to surface markers of T cell subsets. RESULTS: Estrogen treatment causes a dramatic reduction of thymic size and cellularity. All defined T cell subsets of CD4 and CD8 were reduced, with a disproportionate loss of CD4+CD8+ double positive cells. Examination of the triple negative (CD3-CD4-CD8-) subset revealed a striking loss of TN developmental progression of the early precursor cells. Based on the expression of CD44 (pgp-1) and CD25 (IL-2Rα) markers, the TN thymic compartment was composed almost entirely of the earliest population (CD44+, CD25-), with the remaining maturational stages (CD44+, CD25+; CD44-, CD25+; CD44-, CD25-) depleted. In contrast, all T cell developmental stages in the thymus were found to be in normal proportions in the oophorectomized mice, with no differences in the splenic T and B cell subsets. CONCLUSIONS: The study demonstrates that estrogen but not progesterone blocks T cell development in the thymus. However, contrary to our expectation, estrogen deprivation by oophorectomy does not enhance T cell development.