齐留通干预ALOX5对RSV感染后小鼠气道炎症与AHR的影响

目的 观察齐留通干预花生四烯酸5脂氧合酶（ALOX5）蛋白对呼吸道合胞病毒（RSV）感染引起的气道炎症与气道高反应性（AHR）的影响。方法 6～8周雌性Balb/c小鼠随机分为对照组、RSV组和RSV+齐留通组,感染后第5天以Western blot检测各组肺组织中ALOX5蛋白水平。苏木精-伊红（HE）染色观察肺部病理损伤;检测各组小鼠支气管肺泡灌洗液（BALF）中细胞总数及分类计数;全身体积描述记法检测小鼠气道反应性;ELISA检测BALF中cys-LTs、IL-6、IL-8水平;探针法RTPCR检测肺组织中RSV A2 N基因拷贝数。结果 RSV感染后第5天,小鼠肺组织中ALOX5蛋白水平升高,于齐留通干预后降低。齐留通可显著改善RSV感染后小鼠肺部病理损害、BALF中炎症细胞募集及AHR;齐留通干预后BALF中cys-LTs、IL-6、IL-8水平显著降低,但RSV N基因拷贝数无改变。结论 齐留通可抑制ALOX5蛋白表达,减少炎症因子产生,改善RSV感染后小鼠气道炎症与AHR。     

RSV感染裸鼠模型建立及病理特征分析

目的建立呼吸道合胞病毒(respiratory syncytial virus,RSV)感染裸鼠模型,在排除T细胞干扰的情况下,观察RSV的复制情况、气道炎症细胞浸润、肺组织损伤及气道高反应性(AHR),为进一步探讨固有免疫在RSV中的致病作用奠定基础。方法6~8周雌性T细胞缺陷裸鼠(Balb/c背景)及正常Balb/c小鼠分为对照组及RSV组,分别滴鼻接种细胞培养上清或RSV A2病毒液,空斑实验检测病毒滴度;灌取支气管肺泡灌洗液并行炎症细胞计数及分类计数;部分小鼠取左肺,HE染色后行组织病理评分;肺功能检测用全身体积描技法;细胞因子检测用ELISA法。结果裸鼠中病毒清除较Balb/c小鼠延迟;RSV在裸鼠及Balb/c小鼠中均引起明显的炎症细胞浸润、肺组织病理损伤及AHR,且至少可持续60 d;RSV感染裸鼠及Balb/c小鼠后,细胞因子呈双相变化,急性期以干扰素升高为主,慢性期以Th2类细胞因子升高为主。结论固有免疫可不依赖于T细胞,独立介导RSV相关急慢性期气道炎症及AHR,提示RSV疫苗或药物的开发应充分考虑固有免疫的作用。     

脂多糖对呼吸道合胞病毒感染小鼠气道炎症及气道高反应性的影响及其机制研究

目的探讨脂多糖(LPS)对呼吸道合胞病毒(RSV)感染小鼠的气道炎症及气道高反应性的影响及其机制。方法将6~8周龄雌性Balb/c小鼠分为4组:对照组、LPS组、RSV组及RSV+LPS组,于首次处理后第7天收取肺组织、肺泡灌洗液标本,QPCR检测肺组织病毒拷贝数,计数肺泡灌洗液(BALF)中细胞总数及分类计数,HE染色观察肺部病理损伤,肺功能测定AHR,Western blot检测TRIF和MyD88蛋白表达,ELISA检测BALF中IFN-γ、KC、IL-1β、IL-6质量浓度。结果 RSV+LPS组病毒拷贝数与RSV组基本一致。RSV+LPS组BALF中细胞总数较LPS组、RSV组增加,且RSV组以淋巴细胞为主,RSV+LPS组以中性粒细胞为主。LPS组、RSV组、RSV+LPS组肺组织炎症及评分均较对照组明显增高。RSV+LPS组AHR较RSV组、LPS组增高。RSV+LPS组肺组织中TRIF表达较LPS组、RSV组增高,各组MyD88基本无变化。RSV组BALF中IFN-γ明显增高,RSV+LPS组KC明显增高,IL-1β、IL-6各组基本无变化。结论 LPS刺激可通过TRIF-KC途径加重RSV感染小鼠气道炎症及AHR。     

呼吸道合胞病毒感染后期OVA刺激对小鼠气道炎症及AHR的影响

目的研究呼吸道合胞病毒(RSV)感染后期过敏原刺激对小鼠气道炎症及AHR的影响。方法 6~8周龄雌性Balb/c小鼠随机分为Mock组、RSV组、OVA组及R+O组。检测各组小鼠支气管肺泡灌洗液(BALF)中细胞总数及分类计数;苏木精-伊红(HE)染色观察肺部病理损伤;全身体积描述记法检测小鼠气道反应性;ELISA检测BALF中IL-4、IL-5、CXCL10、CCL5、CCL20的水平。结果 R+O组小鼠BALF中炎症细胞总数、巨噬细胞、中性粒细胞及嗜酸性粒细胞分类计数较其他3组均显著增高(P0.05);R+O组小鼠肺组织病理评分及AHR较其他3组亦显著增高(P0.05);BALF中各处理组IL-4、IL-5较Mock组明显增高(P0.05),但处理组之间无显著性差异;R+O组CXCL10水平较其他3组显著升高(P0.05)。结论 RSV感染后期接受OVA刺激可致CXCL10表达增加,进而促使巨噬细胞、中性粒细胞及嗜酸性粒细胞募集,加重小鼠气道炎症及AHR。     

地塞米松对呼吸道合胞病毒感染哮喘加重小鼠气道TSLP分泌及炎症的影响

目的:探讨地塞米松(DEX)对呼吸道合胞病毒(RSV)感染哮喘加重小鼠胸腺基质淋巴细胞生成素(TSLP)分泌及气道炎症的影响。方法:雌性BALB/c小鼠32只,随机分成4组,分别为磷酸盐缓冲液(PBS)对照组、鸡卵白蛋白(OVA)组、OVA/RSV组、OVA/RSV/DEX组;应用OVA腹腔注射致敏、OVA气道雾化结合RSV滴鼻激发哮喘,地塞米松1mg/kg肌肉注射;无创肺功能检测各组小鼠气道反应性;ELISA法检测小鼠血清IL-4、IL-5、IL-13、IFNγ-和气管灌洗液(BALF)TSLP含量;小鼠肺组织病理观察炎症反应,免疫组化观察小鼠气道上皮细胞TSLP表达水平。结果:无创肺功能检测显示地塞米松抑制RSV感染哮喘加重小鼠气道反应性的增高,OVA/RSV/DEX组小鼠Penh值明显低于OVA/RSV组(P<0.01);OVA/RSV/DEX组小鼠血清IL-4、IL-5、IL-13、IFNγ-浓度[分别为(86.78±27.04)、(227.66±40.87)、(194.65±73.27)和(17.33±3.06)pg/ml]和BALF中TSLP浓度[(1 873±10)pg/ml],均明显低于OVA/RSV组[分别为(274.2±103.7)、(293.3±46.1)、(330±93.5)、(30.1±5.7)、(2 127±46)pg/ml](P<0.01);病理观察显示地塞米松显著减轻RSV感染哮喘小鼠气道炎症细胞浸润;免疫组化染色证实地塞米松抑制RSV感染哮喘小鼠气道上皮细胞TSLP表达。结论:地塞米松可以抑制RSV感染哮喘加重小鼠气道上皮细胞表达TSLP,减轻RSV感染哮喘加重小鼠气道炎症反应。     

RNAi技术对改善小鼠呼吸道合胞病毒感染后气道炎症的研究

目的 探讨小鼠呼吸道合胞病毒(respiratory syncytial virus,RSV)感染后气道的炎症反应以及采用小分子RNA技术（smallinterference RNA,siRNA）治疗对气道炎症的改善作用。方法 采用针对RSV -M2基因的特异性siRNA滴鼻治疗RSV感染的RALB/c鼠,通过显微镜观察支气管肺泡灌洗液(BALF)白细胞计数及ELASA方法检测BALF中细胞因子IFN-γ、IL-12和IL-10水平的变化情况。结果 RSV感染后,BALF白细胞总数显著增加,分类以淋巴细胞为主;细胞因子IFN－γ、IL-12和IL-10水平升高;siRNA治疗后,白细胞总数、淋巴细胞、百分数随着siRNA浓度的增加而下降。IFN-Y、IL-12和IL-10水平随着siRNA浓度的增加而下降,与对照组比较差异有统计学意义(P＜0.05)。结论 RSV感染小鼠后,气道发生炎症反应;siRNA技术能够减轻RSV感染后的气道炎症反应。     

RNAi技术对改善小鼠呼吸道合胞病毒感染后气道炎症的研究北大核心CSCD

目的探讨小鼠呼吸道合胞病毒（respiratory syncytial virus,RSV）感染后气道的炎症反应以及采用小分子RNA技术（smallinterferenceRNA,siRNA）治疗对气道炎症的改善作用。方法采用针对RSV-M2基因的特异性siRNA滴鼻治疗RSV感染的hALB／c鼠,通过显微镜观察支气管肺泡灌洗液（BALF）白细胞计数及ELASA方法检测BALF中细胞因子IFN-γ、IL-12和IL-10水平的变化情况。结果RSV感染后,BALF白细胞总数显著增加,分类以淋巴细胞为主;细胞因子IFN-γ、IL-12和IL-10水平升高;siRNA治疗后,白细胞总数、淋巴细胞、百分数随着siRNA浓度的增加而下降。IFN-γ、IL-12和IL-10水平随着siRNA浓度的增加而下降,与对照组比较差异有统计学意义（P〈0．05）。结论RSV感染小鼠后,气道发生炎症反应;siRNA技术能够减轻RSV感染后的气道炎症反应。     

幼年期肺炎链球菌肺炎对哮喘形成的影响

目的研究幼年期肺炎链球菌肺炎(S.pneumoniaepneumonia,S.pp)对成年期哮喘形成的影响。方法 3周龄雌性Balb/c小鼠随机分为对照组(control)、幼年期肺炎链球菌肺炎组(Inf S.pp)、哮喘组(OVA)、幼年期肺炎链球菌肺炎哮喘组(Inf S.pp+OVA)。3周龄雌性Balb/c小鼠鼻腔滴注2×106cfu/ml肺炎链球菌25μl建立肺炎链球菌肺炎模型,成年期用OVA致敏激发Balb/c小鼠建立哮喘模型,最后1次激发完成24 h内检测小鼠气道高反应性,HE染色制作肺组织病理切片,观察组织病理变化,检测支气管肺泡灌洗液(bronchoalveolar lavage fluid,BALF)中细胞总数、细胞分类计数及细胞因子水平,流式细胞术检测小鼠肺组织中CD4~+T细胞水平。结果幼年期肺炎链球菌肺炎哮喘组肺组织炎症细胞侵润、气道反应性、BALF细胞总数、嗜酸性粒细胞和中性粒细胞及细胞因子IL-5、IL-13、IL-17水平显著高于对照组(P0.05),IFN-γ、IL-10表达显著降低(P0.05),肺组织内Th2、Th17水平显著高于对照组(P0.05),Foxp3~+Treg水平显著降低(P0.01),Th1/Th2、Foxp3~+Treg/Th17比例明显降低(P0.01)。幼年期肺炎链球菌肺炎哮喘组肺组织炎症细胞侵润、气道高反应性、BALF细胞分类计数及炎性因子水平、肺组织CD4~+T细胞水平与哮喘组比较无统计学差异。结论幼年期肺炎链球菌肺炎对成年期哮喘形成无显著影响。     

皮下注射和口服螨制剂脱敏在调节小鼠气道炎症和IgE中作用的比较

为了比较皮下注射和口服螨制剂脱敏在调节小鼠气道炎症和血清IgE中的作用。建立粉尘螨主要过敏原 (Df2 )致BALB/c小鼠气道炎症模型 ,以不同剂量的Df2经皮下注射和口服脱敏 ,检测小鼠支气管肺泡灌洗液 (BALF )中炎症细胞总数及分类、气道炎症细胞浸润程度、小鼠血清总IgE及Df2特异性IgE。结果 :皮下注射组和口服组BALF中炎症细胞总数及嗜酸粒细胞百分比较模型组明显降低 ,气道炎症细胞浸润有所减轻 ,皮下注射组和口服组小鼠血清总IgE均明显降低 ,皮下注射组Df2特异性IgE吸光度值明显降低 ,口服组Df2特异性IgE吸光度值与模型组无明显差异。本实验显示皮下注射和口服脱敏均可减轻该模型小鼠气道炎症细胞浸润 ,皮下注射降低特异性IgE的作用优于口服脱敏。     

HSP70/CD80嵌合DNA疫苗对哮喘小鼠气道炎症和气道高反应性的作用

目的 研究HSP70/CD80嵌合DNA质粒对哮喘小鼠气道炎症和气道高反应性的作用,为安全可靠的新型免疫调节性疫苗奠定基础.方法 将40只雌性健康BALB/c小鼠随机分为4组:对照组、哮喘组、pcDNA3.1载体组、HSP70/CD80嵌合DNA疫苗组,每组10只.用HSP70/CD80嵌合疫苗免疫小鼠后,建立鸡卵清蛋白致敏的小鼠哮喘模型,观察其气道阻力变化,支气管肺泡灌洗液中IL-13、IFN-γ含量的变化.取肺组织进行病理组织学分析,观察肺内炎症情况.结果 HSP70/CD80嵌合DNA疫苗免疫小鼠后,能有效减轻气道炎症(P＜0.05),降低气道阻力(P＜0.05),肺泡灌洗液中IFNl的分泌增加(P＜0.05),IL-13降低.结论 HSP70/CD80嵌合DNA疫苗可促进免疫反应向Th1偏移并增加IFN-γ的生成,减轻气道炎症,降低气道阻力,这为过敏性哮喘新型免疫调节性疫苗的机制及应用研究提供了实验资料.     

Sustained increases in numbers of pulmonary dendritic cells after respiratory syncytial virus infection

BACKGROUND: Respiratory syncytial virus (RSV) bronchiolitis in infants can lead to wheezing and early allergic sensitization. In mice, RSV infection enhances allergic airway inflammation and airway hyperresponsiveness. Dendritic cells are critical in inducing T-cell responses to both viruses and allergens and could be pivotal in regulating interactions between these. OBJECTIVE: This study addresses the effects of RSV infection on phenotype and function of pulmonary dendritic cells. METHODS: BALB/c mice were infected with RSV, and expression of CD11c, MHC II, and CD86 on lung and spleen cells was monitored by flow cytometry for 21 days after infection. CD11c(+) cells were isolated to assess their phagocytic capacity and their ability to induce proliferation in allogenic T cells. RESULTS: Numbers of pulmonary CD11c(+) MHC II(hi) cells increased 13-fold starting from day 6 after RSV infection. This was associated with increased CD86 expression, reduced phagocytosis, and increased allogenic T-cell stimulatory capacity in CD11c(+) cells. These changes in the lung outlasted acute infection and were not observed in spleens. CONCLUSION: RSV infection results in sustained increases in numbers of mature dendritic cells in the lung. These might well contribute to the development of intense airway inflammation and airway hyperresponsiveness after RSV infection and to enhancement of subsequent responses to allergen exposure.     

BALB/c鼠和裸鼠呼吸道合胞病毒感染比较研究

目的 比较普通BALB/c鼠和裸鼠呼吸道合胞病毒(RSV)感染免疫及炎症反应特点.方法 BALB/c鼠和裸鼠感染RSV后不同时间空斑形成试验检测肺组织病毒滴度,计数支气管肺泡灌洗液(BALF)白细胞总数和分类,HE染色分析肺组织病理学改变,免疫组化检测肺组织F4/80+细胞和CD49b+细胞.ELISA检测BALF中TNF-α、IFN-r、IL-12和IL-10浓度.结果 BALB/c鼠和裸鼠感染RSV后肺组织病毒滴度在第3天达峰值,感染裸鼠带毒时间更长,在感染后各天病毒滴度明显高于BALB/c鼠(P＜0.05),肺组织病理改变也更重.感染BALB/c鼠和裸鼠BALF白细胞总数明显升高,分类以淋巴细胞为主.感染裸鼠与感染BALB/c鼠比较,肺组织检测到更多的F4/80+巨噬细胞和CD49b+NK细胞(P＜0.05),BALF中TNF-α、IL-12和IL-10水平更高(P＜0.05).结论 RSV感染裸鼠与BALB/c鼠比较,病毒复制水平更高,时间更持久,炎症反应更重.单核巨噬细胞和NK细胞是RSV感染重要的免疫细胞和炎症细胞,炎症反应强度并不一定与T细胞免疫应答平行.     

Detection of pathogenic intestinal bacteria by Toll-like receptor 5 on intestinal CD11c+ lamina propria cells

Toll-like receptors (TLRs) recognize distinct microbial components and induce innate immune responses. TLR5 is triggered by bacterial flagellin. Here we generated Tlr5-/- mice and assessed TLR5 function in vivo. Unlike other TLRs, TLR5 was not expressed on conventional dendritic cells or macrophages. In contrast, TLR5 was expressed mainly on intestinal CD11c+ lamina propria cells (LPCs). CD11c+ LPCs detected pathogenic bacteria and secreted proinflammatory cytokines in a TLR5-dependent way. However, CD11c+ LPCs do not express TLR4 and did not secrete proinflammatory cytokines after exposure to a commensal bacterium. Notably, transport of pathogenic Salmonella typhimurium from the intestinal tract to mesenteric lymph nodes was impaired in Tlr5-/- mice. These data suggest that CD11c+ LPCs, via TLR5, detect and are used by pathogenic bacteria in the intestinal lumen.     

The histopathology of fatal untreated human respiratory syncytial virus infection.

The pathology of respiratory syncytial virus (RSV) infection was evaluated 1 day after an outpatient diagnosis of RSV in a child who died in a motor vehicle accident. We then identified 11 children with bronchiolitis from the Vanderbilt University autopsy log between 1925 and 1959 who met criteria for possible RSV infection in the preintensivist era. Their tissue was re-embedded and evaluated by routine hematoxylin and eosin and PAS staining and immunostaining with RSV-specific antibodies. Tissue from three cases was immunostain-positive for RSV antigen and was examined in detail. Small bronchiole epithelium was circumferentially infected, but basal cells were spared. Both type 1 and 2 alveolar pneumocytes were also infected. Although, not possible for archival cases, tissue from the index case was evaluated by immunostaining with antibodies to define the cellular components of the inflammatory response. Inflammatory infiltrates were centered on bronchial and pulmonary arterioles and consisted of primarily CD69+ monocytes, CD3+ double-negative T cells, CD8+ T cells, and neutrophils. The neutrophil distribution was predominantly between arterioles and airways, while the mononuclear cell distribution was in both airways and lung parenchyma. Most inflammatory cells were concentrated submuscular to the airway, but many cells traversed the smooth muscle into the airway epithelium and lumen. Airway obstruction was a prominent feature in all cases attributed to epithelial and inflammatory cell debris mixed with fibrin, mucus, and edema, and compounded by compression from hyperplastic lymphoid follicles. These findings inform our understanding of RSV pathogenesis and may facilitate the development of new approaches for prevention and treatment.     

Understanding respiratory syncytial virus (RSV) vaccine-enhanced disease

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection in infants and children worldwide. In addition, RSV causes serious disease in elderly and immune compromised individuals. RSV infection of children previously immunized with a formalin-inactivated (FI)-RSV vaccine is associated with enhanced disease and pulmonary eosinophilia that is believed to be due to an exaggerated memory Th2 response. As a consequence, there is currently no licensed RSV vaccine and detailed studies directed towards prevention of vaccine-associated disease are a critical first step in the development of a safe and effective vaccine. The BALB/c mouse model of RSV infection faithfully mimics the human respiratory disease. Mice previously immunized with either FI-RSV or a recombinant vaccinia virus (vv) that expresses the attachment (G) glycoprotein exhibit extensive lung inflammation and injury, pulmonary eosinophilia, and enhanced disease following challenge RSV infection. CD4 T cells secreting Th2 cytokines are necessary for this response because their depletion eliminates eosinophilia. Intriguing recent studies have demonstrated that RSV-specific CD8 T cells can inhibit Th2-mediated pulmonary eosinophilia in vvG-primed mice by as yet unknown mechanisms. Information gained from the animal models will provide important information and novel approaches for the rational design of a safe and efficacious RSV vaccine.     

Increased pathogenesis and inflammation of airways from respiratory syncytial virus infection in T cell deficient nude mice

Respiratory syncytial virus (RSV) infection is ubiquitous and leads to various outcomes between immunocompetent and immunocompromised individuals. This study aimed to compare RSV infection and inflammatory responses between immunocompetent BALB/c mice and immunodeficient nude mice. RSV titers in both infected BALB/c mice and nude mice peaked on the third day post-inoculation, but the nude mice had longer lasting and higher levels of viral replication. RSV infection induced a more severe grade of pulmonary histopathology and larger numbers of leukocytes in airways of nude mice than that of BALB/c mice. RSV infection increased pulmonary macrophages and natural killer (NK) cells in both strains of mice. Furthermore, infected nude mice had larger numbers of pulmonary macrophages and NK cells than infected BALB/c mice. Whereas the RSV infected BALB/c mice secreted more tumor necrosis factor -alpha (TNF-alpha), interleukin-12 (IL-12), interferon-gamma (IFN-gamma) and IL-10 than control BALB/c mice, the infected nude mice had higher levels of TNF-alpha, IL-12 and IL-10 than the infected BALB/c mice. The inflammation induced by RSV infection did not correspond with the immune response of T cells. Macrophages and NK cells were potent immunocytes and inflammatory cells in RSV infection especially when T lymphocytes were deficient. Therefore, nude mice may be a good model for severe and persistent RSV infection in immunocompromised hosts.     

Expression of CTLA-4 (CD152) in peripheral blood T cells of children with influenza virus infection including encephalopathy in comparison with respiratory syncytial virus infection

Influenza virus and respiratory syncytial virus (RSV) are the most common causes of acute severe respiratory infection in children during the winter. There have been few reports about peripheral blood T cell activation in vivo in influenza virus infection and conflicting results concerning peripheral blood T cells activation in RSV infection. Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4, CD152) is a receptor present on T cells that plays a critical role in the down-regulation of antigen-activated immune responses. To clarify the status of peripheral blood T cells, we investigated intracellular CTLA-4 expression in T cells in patients with influenza virus and RSV infection. We collected blood samples from 15 patients with influenza virus infection, including three with complications of influenza virus-associated encephalopathy and 18 patients with RSV infection, as well as 44 healthy children. We determined the intracellular expression of CTLA-4 in CD4+ and CD8+ T cells by flow cytometry. There were no significant differences in the percentages of intracellular CTLA-4-positive CD4+ T cells and CD8+ T cells by age. The percentages of intracellular CTLA-4-positive CD4+ T cells in the patients with influenza virus infection were significantly higher than those in healthy children (P < 0.01). In particular, the patients with influenza virus-associated encephalopathy had sevenfold higher percentages of CTLA-4-positive CD4+ T cells than influenza patients without encephalopathy (P < 0.05). The patients with influenza virus-associated encephalopathy had increased percentages of CTLA-4-positive CD8+ cells at the acute stage in comparison with the convalescent stage and in control subjects (P < 0.01, respectively). RSV patients showed no increase in CTLA-4-positive CD4+ T cells or CD8+ T cells. The immunological status of peripheral T cell activation is substantially different in influenza virus infection and RSV infection. The patients with RSV infection did not show any increase in CTLA-4-positive peripheral blood T cells. There was a remarkable increase in intracellular CTLA-4 in CD4+ and CD8+ T cells in influenza virus-associated encephalopathy. Down-regulation of antigen-activated peripheral blood T cell activation might play an important role in the pathogenesis of influenza virus-associated encephalopathy and host defence against influenza virus infection.     

T cell redistribution kinetics after secondary infection of BALB/c mice with respiratory syncytial virus.

BALB/c mice were infected intranasally with live respiratory syncytial virus (RSV) and reinfected 4 weeks later. At regular intervals thereafter groups of animals were killed and T cell subsets were determined in blood, spleen and bronchoalveolar lavage (BAL) with flow cytometry employing T cell subset-specific MoAbs. Total lymphocyte counts in the peripheral blood decreased 1-3 days after infection, returning to preinfection levels on day 8 (P = 0.0111). Simultaneously, a marked increase of lymphocytes was noted in the BAL, reaching a maximum at day 8 (P < 0.0001). Both CD4+ and CD8+ T cells decreased in the blood on day 1-3 (P < 0.0097 and P = 0.003 respectively), and increased in the BAL progressively towards a maximum at day 8 (P < 0.0001). In BAL, CD4+ cells increased 35-fold and CD8+ cells 27-fold during the first week after reinfection. On the other hand, in the spleen a significant decline of CD4+ and CD8+ cells was noted 1 day post-infection (P = 0.0002). It is concluded that a strong T cell redistribution response among systemic and mucosal tissues occurs after reinfection with RSV. The kinetics of this response differ both quantitatively and qualitatively from the T cell response after primary infection. The magnitude of cell traffic is more pronounced in blood, spleen and BAL than after primary infection. CD4+ T cells are more intensively distributed to the lungs than after primary infection.     

The impact of splenectomy on antiviral T cell memory in mice

The contribution of the spleen to protective antiviral T cell memory was studied using the mouse model of infection with respiratory syncytial virus (RSV). Virus-specific CD8+ memory T cells were induced by local (intranasal or intracutaneous) or systemic (intravenous) immunization using RSV or vaccinia virus-recombinants expressing an RSV protein. After all three routes of immunization, the spleen was clearly identified as the main anatomic compartment harbouring virus-specific memory T cells. Surprisingly, however, splenectomy performed 30 days after immunization did not impair the efficacy of the memory T cell response to a subsequent RSV challenge infection. Irrespective of the route of priming, splenectomy did not influence the number or the functional activity of virus-specific memory T cells recruited to the lung following RSV challenge. More importantly, splenectomy did not impair pulmonary virus control by antiviral memory T cells in vivo. These findings were confirmed under experimental conditions where no neutralizing antibodies were induced by the priming infection. Thus, although most memory CD8+ T cells localize to the spleen after viral infections, this important lymphoid organ is dispensable for efficient recall responses. These findings have implications for the immunocompetence of splenectomized patients.     

Clearance of persistent respiratory syncytial virus infections in immunodeficient mice following transfer of primed T cells.

Little is known of the role of T-cell mediated immune responses in the clearance and pathogenesis of respiratory syncytial virus (RSV) infection. In this study, we established persistent pulmonary RSV infections in athymic nu/nu BALB/c mice or immunodeficient irradiated BALB/c mice, and examined the patterns of virus clearance following adoptive transfer of splenic memory T cells. Primed T cells transferred between Day 5 and Day 8 of infection will clear lung RSV from both nu/nu mice and irradiated mice within 10 days of transfer. Partially purified Lyt 2+ T cells are more effective than L3T4+-selected T cells. No RSV-specific serum antibody could be detected, suggesting that clearance is by an antibody-independent mechanism. In contrast, delayed (Day 14) transfer of primed L3T4+-selected cells clears lung RSV from nu/nu mice, and this correlates with RSV-specific serum antibody production. Clearance is not seen following Day 14 transfer of total primed T cells or T cells selected for the Lyt 2+ subset.