Recognition of a novel naturally processed, A2 restricted, HCV-NS4 epitope triggers IFN-gamma release in absence of detectable cytopathicity

Using short term CTL lines derived from HLA A2/K^b transgenic mice and IFN-gamma release assays we demonstrate that the NS4.1769 epitope, is generated from natural processing of the NS4 antigen, and presented in the context of the A2/K^b molecules. Interestingly, T cell recognition of the naturally processed form of the NS4.1769 epitope was associated with significant IFN-gamma release, but no direct cytolytic activity. Epitopes of this phenotype might be of interest, in terms of therapy of chronic HCV infection by associating the benefit of localized lymphokine release with low or absent direct cytopathicity.     

Activation of the JAK/STAT Pathway in Epstein Barr Virus+-Associated Posttransplant Lymphoproliferative Disease: Role of Interferon-γ

Epstein Barr virus (EBV) is associated with B-cell lymphomas in posttransplant lymphoproliferative disease (PTLD). Latent membrane protein 1 (LMP1), the major oncogenic protein of EBV, promotes tumorigenesis through activation of NF-κB, Erk, p38, JNK and Akt. The Jak/STAT signal transduction pathway is also constitutively active in PTLD-associated EBV⁺ B-cell lymphomas. Here we determine the mechanism of Jak/STAT activation in EBV⁺ B-cell lymphomas and the role of LMP1 in this process. Immunoprecipitation studies revealed no direct interaction of LMP1 and JAK3, but known associations between JAK3 and common gamma chain, and between LMP1 and TRAF3, were readily detected in EBV⁺ B cell lines from patients with PTLD. An inducible LMP1 molecule expressed in EBV⁻ BL41 Burkitt's cells demonstrated STAT activation only after prolonged LMP1 signaling. While LMP1 induced IFN-γ production in BL41 cells, IFN-γ receptor blockade and IFN-γ neutralization prior to LMP1 activation markedly decreased STAT1 activation and expression of LMP1-driven IFN-γ inducible genes. Understanding the mechanisms by which EBV induces cellular signal transduction pathways may facilitate development of new treatments for PTLD.     

Functional properties and epitope characteristics of T-cells recognizing natural HIV-1 variants

To understand how broad recognition of HIV-1 variants may be achieved we examined T-cell reactivity in newly infected persons as well as vaccine recipients to a broad spectrum of potential T-cell epitope (PTE) variants containing conservative, semi-conservative and non-conservative amino acid substitutions. Among early infected persons T-cells recognized epitope variants with one substitution at a significantly higher frequency versus those with two (P = 0.0098) and three (P = 0.0125) substitutions. Furthermore T-cells recognized variants containing conservative substitutions at a higher frequency versus those containing semi-conservative (P = 0.0029) and non-conservative (P < 0.0001) substitutions. Similar effects were observed on recognition of variants by vaccine-induced T-cells. Moreover even when variants were recognized, the IFN-γ and granzyme B responses as well as T-cell proliferation were of lower magnitude. Finally, we show that epitope distribution is strongly influenced by both processing preferences and amino acid entropy. We conclude that induction of broad immunity is likely to require immunogen sequences that encompass multiple variants. However, cost-effective design of peptide and sequence based vaccine immunogens that provide maximal coverage of circulating sequences may be achieved through emphasis on virus domains likely to be T-cell targets.     

Comparison of DNA vaccines producing HIV-1 Gag and LAMP/Gag chimera in rhesus macaques reveals antigen-specific T-cell responses with distinct phenotypes

Optimized DNA expression vectors encoding the native HIV-1 Gag or a fusion of Gag with the lysosomal membrane associated protein 1 (LAMP) were compared for immunogenicity upon intramuscular DNA delivery in rhesus macaques. Both vaccines elicited CD4⁺ T-cell responses, but with significant differences in the phenotype of the Gag-specific cells: the native Gag induced CD4⁺ responses with a phenotype of central memory-like T cells (CD28⁺ CD45RA⁻), whereas the LAMP/Gag chimera induced CD4⁺ responses with effector memory phenotype (CD28⁻ CD45RA⁻). Antigen-specific T cells producing both IFN-γ and TNFα were found in the animals receiving the native Gag, whereas the LAMP/Gag chimera induced humoral responses faster. These results demonstrate that modification of intracellular Gag trafficking results in the induction of distinct immune responses. Combinations of DNA vectors encoding both forms of antigen may be more potent in eliciting anti-HIV-1 immunity.     

Modulation of T-cell responsiveness during Trypanosoma cruzi infection: analysis in different lymphoid compartments

Spleen and lymph node cells of Trypanosoma cruzi-infected mice were studied for mitogen-induced responsiveness in terms of proliferation and lymphokine production (IL-2, IFN-gamma). Splenocyte (SP) as well as lymph node cell (LN) proliferation and IL-2 production were depressed during the acute phase of the infection. Proliferative capacity of LN cells recovered completely and that of SP partially during the chronic phase. In contrast to these suppressive effects, the mitogen-induced IFN-gamma response was enhanced. In vitro co-incubation of normal SP or LN cells with trypomastigotes resulted in a reduced mitogen-induced cell proliferation and IL-2 secretion, similar to those seen with cells taken from infected mice. In contrast, trypomastigotes exerted a stimulatory activity on the mitogen-induced IFN-gamma response of both SP and LN cells. Addition of lymph node cells from T. cruzi-infected mice (LN-I) to lymph node cells of control mice (LN-C) suppressed strongly the mitogen-induced responsiveness of such cocultures. A marginal level of suppression was recorded in cocultures of spleen cells from infected mice (SP-I) and control spleen cells (SP-C). The potent suppressive cells within LN-I populations were identified as macrophage-like and such cells were absent in SP-C and peritoneal exudate cells from T. cruzi infected animals.     

Monoclonal antibodies to human immune interferon and their application for affinity chromatography

Two IgG1/kappa class monoclonal antibodies specific for human immune interferon (IFN-gamma), designated B1 and B3, were developed. Specific binding of both monoclonal antibodies to natural or Escherichia coli-derived recombinant human IFN-gamma was demonstrated in a solid-phase radioimmunoassay or by immunoprecipitation. Antibody B3 showed potent neutralizing activity against both natural and recombinant IFN-gamma. Antibody B1, which showed neutralizing activity only when very high concentrations were employed, was used for preparing immunosorbents for affinity chromatography of IFN-gamma. When a highly purified preparation of 125I-labeled natural IFN-gamma was loaded onto the affinity column, all of the biological activity was retained on the column. The bulk of 125I-labeled IFN-gamma bound to the affinity column be eluted in biologically active form, suggesting that antibody B1 could be used for the purification of human IFN-gamma. Analysis of IFN-gamma eluted from the column by NaDodSO4/polyacrylamide gel electrophoresis (SDS-PAGE) indicated that both of the known molecular weight subspecies of IFN-gamma (25,000 and 20,000 MW), as well as the presumed dimer of 45,000 MW, were retained by the B1 antibody affinity column.     

妇炎舒胶囊联合抗生素治疗慢性盆腔炎疗效分析

目的观察中药妇炎舒胶囊联合盐酸左氧氟沙星片和甲硝唑片治疗慢性盆腔炎患者的疗效和相关炎性因子的影响。方法收取118例湿热瘀结型慢性盆腔炎的患者,随机分为实验组(A组)和对照组(B组)各59例。A组给予妇炎舒胶囊56 d,B组妇炎舒胶囊模拟剂56 d,两组均服用盐酸左氧氟沙星片+甲硝唑片用药14 d。患者服药56 d后观察临床有效率及治疗前后血清中肿瘤坏死因子-α(Tumor necrosis factor,TNF-α),干扰素-γ(Interferon,IFN-γ)因子含量的变化;随访1个月经周期后观察者复发率及慢性盆腔痛情况。结果(1)A组中医证候积分有效率明显高于B组,且差异有统计学意义(P<0.01)。(2)治疗后A组患者外周血中TNF-α和IFN-γ的含量明显低于B组,具有显著统计学差异(P<0.01)。(3)A组随访复发率(10.17%vs 96.61%)和后遗盆腔痛(18.64%vs 86.44%)均显著低于B组(P<0.01)。结论中药妇炎舒胶囊联合抗生素治疗湿热瘀结型慢性盆腔炎疗效显著,并能够降低慢性盆腔炎的复发率和慢性盆腔痛,并能通过适当降低外周血中TNF-α、IFN-γ等炎性因子的形成,起到治疗作用。     

急性冠脉综合征患者辅助性T细胞亚群变化及意义

目的：探讨急性冠脉综合征(ACS)患者外周血辅助性T淋巴(Th)细胞亚群1和亚群2(TH1/Th2)的变化及意义。方法：64例ACS患者(其中急性心肌梗死(AMI)28例，不稳定心绞痛(UA)36例)、18例稳定型心绞痛(SA)、12例陈旧性心肌梗死(OMI)、21例胸痛综合征(CPS)患者和23例对照(C)外周血单个核细胞(PBMC)经植物血凝素(PHA)刺激培养后，应用酶联免疫吸附方法(ELISA)检测培养液上清中干扰素γ(IFN-γ)和白介素4(IL-4)水平。结果：ACS组培养液上清中IFN-γ水平及IFN-γ/IL-4比值明显高于SA组、OMI组、CPS组和C组，OMI组、SA组、CPS组与C组间无显著性差异；各组间IL-4水平无显著性差异。ACS患者培养液上清中IFN-γ水平随发病时间的延长而逐渐下降，但AMI患者IFN-γ高表达持续时间更长。结论：ACS患者存在Th1／Th2功能失衡，主要表现为Th1细胞功能亢进，可能是ACS的发病机制之一；AMI患者Th1／Th2功能失衡可能参与了AMI后自身免疫因素引起的心肌损伤和心室重塑过程。     

IL-12~+重组卡介苗降低哮喘小鼠气道炎症的作用及其机制研究

目的探讨IL-12+重组卡介苗(recombinant balillus calmette-guerin secreting IL-12,rBCG)新生期接种对实验性哮喘小鼠气道炎症和气道高反应(airway hyperresponsiveness,AHR)的作用及其可能机制。方法新生Balb/c小鼠分4组:对照组(control组),卵白蛋白(OVA)组,rBCG干预(rBCG/OVA)组,rBCG/OVA/IFN-gamma中和抗体(rBCG/OVA/anti-IFN-gamma Ab)组。除对照组外,其余3组均给予OVA致敏和激发。最后一次激发后测24 h内AHR,观察支气管肺泡灌洗液(bronchoalveolarlavage fluid,BALF)中细胞总数及分类,评估肺部炎症变化程度,采用酶联免疫吸附双抗体夹心法(ELISA)检测BALF中IFN-gamma、IL-10水平。结果 1)OVA组BALF中细胞总数、嗜酸性粒细胞、中性粒细胞、淋巴细胞绝对计数和炎症病理评分均明显高于对照组,rBCG/OVA组上述内容均显著低于OVA组。2)新生期rBCG接种能显著降低哮喘小鼠模型的气道高反应性。3)rBCG/OVA组支气管肺泡灌洗液中IFN-gamma、IL-10水平明显高于OVA组。4)rBCG/OVA组与接种rBCG同时并使用anti-IFN-gamma Ab的哮喘小鼠相比气道炎症和AHR无显著差异。结论新生期rBCG接种能抑制哮喘小鼠气道炎症和AHR,促进IFN-gamma和IL-10的产生,其抗哮喘效应可能与其促进IL-10分泌有关。