鄂西北地区汉族人群CD40基因单核苷酸多态性分析

目的研究CD40-E1SNP和E4SNP单核苷酸多态性在鄂西北部地区汉族人群中的分布,并探讨CD40基因单核苷酸多态性与血浆可溶性CD40水平的关系。方法 318例汉族人,其中男性187例,女性131例;平均年龄31.2岁。应用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)及测序的方法,CD40-E1SNP和E4SNP并计算其基因型频率及等位基因频率,酶联免疫吸附分析检测血浆可溶性CD40浓度,并与文献报道不同种族人群比较。结果鄂西北地区汉族人群CD40-E1SNP基因型频率:CC型29.2%,CT型54.1%,TT型16.7%,C、T等位基因频率分别为56.3%、43.7%,这种多态性分布在男女间差异无统计学意义(P>0.05),与英国、波兰比较,发现不同种族间CD40-E1SNP基因型分布及等位基因频率差异均存在统计学意义(P<0.01);CD40-E1SNP各基因表型之间可溶性CD40含量分别为:CC(57.3±6.6)pg/mL,CT(34.2±4.5)pg/mL,TT(28.8±4.2)pg/mL,差异存在统计学意义(P<0.01)。在实验中未检测到CD40-E4SNP单核苷酸多态性。结论鄂西北地区汉族人群中存在CD40-E1SNP单核苷酸多态性,其基因型在不同种族间存在较大的差异,并且可能影响CD40的表达,而不存在CD40-E4SNP单核苷酸多态性。     

抑制素β基因多态性与孕妇子痫前期易感性及新生儿围生结局关联研究

目的 探讨抑制素β基因多态性与孕妇子痫前期易感性及新生儿围生结局关系.方法 选取子痫前期孕妇185例,另选同期正常孕妇120例为对照组.采用聚合酶链限制性片段长度多态性(PCR-RFLP)方法对该位点进行基因分型,比较各组基因型频率和等位基因频率的差异.观察两组孕妇妊娠结局.结果 抑制素β基因rs505922位点共检出CC、CT和TT等3种基因型.子痫前期组与对照组比较,基因型频率与等位基因频率差异有统计学意义(P＜0.05).子痫前期组内CT和CC基因型新生儿窒息、死亡率均高于TT基因型,差异有统计学意义(P＜0.05).结论 抑制素β基因rs505922位点单核苷酸基因多态性与子痫前期密切相关,CT和CC基因型加重了子痫前期的程度,该位点可能是子痫前期孕妇发病的易感位点.     

ATM基因rs227060位点单核苷酸多态性与肺癌易感性的相关性

目的:探讨共济失调毛细血管扩张症突变基因(ataxia telangiectasia mutated,ATM)rs227060位点单核苷酸多态性(single nucleotide polymorphisms,SNPs)与肺癌易感性之间的相关性.方法:采用聚合酶链反应-SNP敏感性分子开关方法,检测225例肺癌患者和128例健康体检者ATM基因rs227060多态位点等位基因以及基因型频率分布特点;并应用非条件Logistic回归法统计分析rs227060单核苷酸多态性与肺癌的相关性.结果:rs227060多态位点共检测出CC,CT,TT三种基因型和C,T两种等位基因,其在肺癌组与对照组的基因型分布频率为:CC基因型17.3％与29.7％、CT基因型61,4％与59.3％、TT基因型21.3％与11％,两组间基因型频率和等位基因频率分布差异均有统计学意义(P＜0.05).在对ATM rs227060基因型的多态性分析过程中发现:吸烟史在肺癌组与对照组相比差异无统计学意义(P＞0.05),而年龄、性别、肿瘤家族史在肺癌组与对照组相比差异均有统计学意义(P＜0.05);且以CC基因型作为对照,携带TT基因型的个体患肺癌的风险是携带CT基因型个体的3.49倍(OR=1.829;95％CI:1.045～3.199).结论:ATM基因rs227060位点单核苷酸多态性与肺癌易感性存在相关性,且携带TT基因型可增加肺癌的发病风险.     

CD40基因5'非翻译区_1位点C/T多态性与Graves病药物治疗停药后复发的相关性

目的:探讨CD40基因5'非翻译区(5'untranslated region,5'UTR)_1位点C/T单核苷酸多态性与山东青岛地区汉族人群Graves病(Graves disease,GD)及药物治疗停药后复发的相关性。方法:应用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)技术测定198例GD患者(其中GD初发组80例,GD早期复发组84例,GD晚期复发组34例)和110例正常对照者CD40基因5'UTR_1位点的基因型,并计算其基因型及等位基因频率。结果:①CD40基因5'UTR_1位点的基因型及等位基因频率在GD组和正常对照组中的分布有显著性差异(χ2=23.133,P=0.000;χ2=13.372,P=0.000),GD组CC基因型频率明显高于正常对照组(23.7%vs11.8%),TT基因型频率明显低于正常对照组(7.6%vs26.4%),GD组C等位基因频率明显高于正常对照组(58.1%vs42.7%);②CD40基因5'UTR_1位点的基因型频率在GD初发组与GD复发组的分布有显著性差异(χ2=7.926,P=0.019);GD复发组TT基因型频率明显低于GD初发组(3.4%vs1...     

广西壮族及汉族人群CD40配体基因rs3092923G/A和rs3092929A/C遗传多态性的研究

目的探讨CD40配体基因rs3092923G/A和rs3092929A/C多态性位点在广西壮族及汉族人群中的分布,同时比较其基因型及等位基因频率分布在不同种族人群之间以及同一种族不同性别之间存在的差异。方法采用单碱基延伸PCR的检测方法,分析201名广西汉族人和199名广西壮族人的CD40配体基因rs3092923G/A和rs3092929A/C多态性。结果在广西壮族人群中,CD40配体基因rs3092923G/A位点AA、AG与GG基因型频率和rs3092929A/C位点AA、AC与CC基因型频率均为86.4%、7.5%和6.0%,rs3092923G/A位点的A、G等位基因频率和rs3092929A/C位点的A、C等位基因频率均为90.2%、9.8%;在广西汉族人群中,CD40配体基因rs3092923G/A位点AA、AG与GG基因型频率和rs3092929A/C位点AA、AC与CC基因型频率均为93.0%、4.0%、3.0%,rs3092923G/A位点的A、G等位基因频率和rs3092929A/C位点的A、C等位基因频率均为95.0%、5.0%。将这2个多态性位点基因型分布频率在2个民族人群中比较,差异均无显著性(P均>0.05),而等位基因频率却有着显著性差异(P均<0.05)。另外,将这2个位点多态性分布频率在男女性别之间作比较,差异都没有显著性(P均>0.05)。进一步与人类基因组计划公布的4个人群相比,广西汉族人群的rs3092923G/A和rs3092929A/C 2位点基因型和等位基因频率与非洲、日本、欧洲和北京人群比较,差异都具有显著性(P均<0.05)。结论在广西地区壮族及汉族人群中存在着CD40配体基因多态性。广西汉族人群CD40配体基因多态性的分布频率同其他种族人群比较存在着显著性差异,这种差异可能是导致与CD40配体相关的疾病在不同种族人群间的临床表现以及发病率存在明显不同的原因之一。     

E-选择素基因第2外显子G98T单核苷酸多态性的调查

目的 :研究湖北地区汉族人群E 选择素 (E selectin)基因第 2外显子 98位点的单核苷酸多态性 (SNP) ,比较种族间单核苷酸的基因频率分布差异。方法 :应用聚合酶链反应 限制性片段长度多态性(PCR RFLP)的分析方法 ,检测了 2 40名健康者E selectin第 2外显子 98位点单核苷酸的基因型。结果 :E selectin各基因型频率GG型91.3 % ,GT型 8.7% ;G ,T各等位基因频率分别为 95 .6% ,4.4% ,这种基因多态性分布在男女间均无显著性差异 (P >0 .0 5 )。与其它种族比较 ,发现不同种族间E selectin基因型分布及等位基因频率均存在显著差异 (P <0 .0 5 )。结论 :在湖北地区汉族人群中存在E se lectin基因第 2外显子 98位点的单核苷酸多态性 ,这种多态性在种族间可能存在着较大的差异     

他克莫司与环孢菌素A对肝移植受者CD4/CD8 T淋巴细胞亚群及共刺激分子的调节作用

目的:探讨他克莫司(Tacrolimus, FK506)与环孢菌素A(CsA)对肝移植受者T淋巴细胞亚群共刺激分子的调节作用.方法:采用荧光标记单克隆抗体(mAb)结合流式细胞技术, 测定移植术后使用FK506或CsA治疗2月末的肝移植受者外周血T细胞亚群及其表面共刺激分子CD28、CD152 和ICOS的表达情况.以健康志愿者(健康对照组)和患终末期肝脏疾病拟进行肝移植者(疾病对照组)为对照.结果:疾病对照组T细胞亚群平衡紊乱、共刺激分子表达异常(P＜0.05).治疗组肝移植受者T淋巴细胞亚群表达恢复至健康对照水平, T细胞表面CD28和ICOS分子表达显著降低(P＜0.05)而CD152分子表达明显升高(P＜0.05).比较不同药物治疗组:CsA治疗组CD4 T细胞表达和CD8 T细胞表面CD28、CD152分子表达均明显高于FK506治疗组(P＜0.05);其他指标无统计学意义(P＞0.05).结论:在常规血药浓度条件下FK506和CsA的对CD4/CD8T细胞亚群及共刺激分子的免疫调节作用存在差异.FK506对T细胞亚群的调节作用强于CsA.FK506可同时抑制正性共刺激分子CD28和ICOS表达并促进负性共刺激分子CD152表达, 而CsA对T细胞免疫抑制作用主要是通过促进CD152分子的高表达介导.     

精氨酸加压素基因多态性在广西人群中的分布

目的探讨精氨酸加压素(AVP)基因单核苷酸多态性(SNP)位点rs2282018、rs3787482和rs1887854在303例广西人群中的分布,并对比不同族群间AVP基因型及等位基因频率分布的差别。方法采用单碱基延伸的聚合酶链反应(PCR)技术和DNA测序法,检测303例广西人AVP基因多态性,分析广西人群3个位点的基因型和等位基因的分布频率,并与人类基因组计划(Hap Map)公布的欧洲人、中国北京汉族人、日本人和非洲人的基因多态性分型数据比较,分析这5个人群人类的基因型及等位基因的分布频率。结果我国广西人群AVP基因rs2282018、rs3787482及rs1887854位点各自具有3种基因型,基因型和等位基因分布与性别无关。与人类基因组计划(Hap Map)公布的欧洲人、非洲人、日本人和中国北京人的单核苷酸多态性分型数据进行比较,广西人群AVP基因不同多态性位点的基因型和等位基因频率在不同地区人群的分布存在差异。结论广西地区人群中存在AVP基因多态性。广西人群AVP基因多态性的分布频率与其他不同地区种族人群比较存在差异。     

家族性热性惊厥与CAPS基因的相关分析

目的研究CAPS(calcyphsine)基因单核苷酸多态性(single nucleotide polymorphisms,SNPs)位点与家族性热性惊厥(febrile seizures,FS)的关系.方法通过NCBI的dbSNP数据库选择CAPS基因的2个单核苷酸多态性位点,应用聚合酶链式反应-限制性内切酶长度多态性技术,检测54例家族性热性惊厥患儿和90名健康对照者的CAPS基因2个SNPs位点的基因型,用SPSS软件判定个单核苷酸多态性基因型频率分布是否符合Hardy-Weinberg平衡,SNPs基因型频率和基因频率在正常人和患儿中的分布比较用R×C和2×2表x2检验并经连续性校正.结果位点rs7249419的基因型频率符合Hardy-Weinberg平衡,但是它的最小等位基因频率不足1%,其基因型频率和等位基因频率在正常人和患儿间的分布无显著性差异(P＞0.05).位点rs11437855只有1种基因型,均为无插入的纯合子.结论CAPS基因SNP rs7249419、rs11437855可能与家族性热性惊厥无关.     

三个不同海拔藏族群体HIF1A基因九个单核苷酸多态性位点研究

目的 研究不同海拔高度的低氧环境差异对基因缺氧诱导因子1α基因(hypoxia inducible factor 1 alpha,HIF1A)的选择作用.方法 选取世居于西藏、青海、云南的3个不同海拔高度的藏族群体,利用聚合酶链反应-限制性片段长度多态性技术检测HIF1A基因的9个单核苷酸多态性(single nucleotide polymorphisms,SNP)位点.结果 所有非同义突变SNP位点的基因型频率与等位基因型频率在3个藏族群体之间差异无统计学意义,而rs11549465位点的基因型频率在云南藏族分别与西藏藏族和青海藏族之间差异有统计学意义(P＜0.05).4个内含子SNP位点基因型频率与等位基因频率在西藏藏族与青海藏族之间差异均无统计学意义;但在西藏藏族和青海藏族分别与云南藏族比较时,基因型频率与等位基因频率差异均有统计学意义(P＜0.05),且跟海拔差异有相关性.结论 海拔高度不同引起的低氧环境差异有可能对 HIF1A 基因有选择作用.     

Targeting lymphocyte co-stimulation: From bench to bedside

T and B lymphocytes are central regulators and effectors of immune responses and are believed to have a key role in many autoimmune diseases. Targeting the activation or effector function of lymphocytes is a potentially effective approach to treat autoimmunity. Typically, T-cell activation occurs after engagement of the T-cell receptor with its cognate peptide-major histocompatibility complex (signal 1) and subsequent engagement of co-stimulatory molecules (signal 2). This “second signal” contributes to T-cell activation by promoting proliferation, survival, and effector function. In general, activation in the absence of co-stimulation leads to a reduced immune response, anergy, or even tolerance. B-cell activation similarly requires co-stimulation for the development of complete effector function. The most potent co-stimulatory molecules identified to date are CD28 for T-cells and CD40 for B-cells. Both molecules are recognized for their potential as immune modulators; however, thus far neither molecule has been successfully targeted directly for the treatment of autoimmune disease. The only current therapy to target either of these pathways is cytotoxic T-lymphocyte antigen-4 (CTLA-4-Ig), which indirectly blocks CD28 signaling and has proven efficacy in rheumatoid arthritis and juvenile idiopathic arthritis patients. In addition to CD28 and CD40, an array of other co-stimulatory as well as inhibitory pathways has recently been identified and scientists are just beginning to understand how these different signaling pathways interact to regulate lymphocyte activation. In the more than two decades since the discovery of the first co-stimulatory molecule, the full clinical potential of these pathways is yet to be realized. In this review, we will primarily focus on CD28 and CD40 which are the most clinically validated co-stimulatory pathways, and briefly summarize and discuss some of the other T-cell co-stimulatory molecules.     

Impact of population admixture on the distribution of immune response co-stimulatory genes polymorphisms in a Brazilian population

Co-stimulatory molecules are essential in the orchestration of immune response and polymorphisms in their genes are associated with various diseases. However, in the case of variable allele frequencies among continental populations, this variation can lead to biases in genetic studies conducted in admixed populations such as those from Brazil. The aim of this study was to evaluate the influence of genomic ancestry on distributions of co-stimulatory genes polymorphisms in an admixed Brazilian population. A total of 273 individuals from the north of Brazil participated in this study. Nine single nucleotide polymorphisms in 7 genes (CD28, CTLA4, ICOS, CD86, CD40, CD40L and BLYS) were determined by polymerase chain reaction-restriction fragment length polymorphism. We also investigated 48 insertion/deletion ancestry markers to characterize individual African, European and Amerindian ancestry proportions in the samples. The analysis showed that the main contribution was European (43.9%) but also a significant contribution of African (31.6%) and Amerindian (24.5%) ancestry. ICOS, CD40L and CD86 polymorphisms were associated with genomic ancestry. However there were no significant differences in the proportions of ancestry for the other SNPs and haplotypes studied. Our findings reinforce the need to apply AIMs in genetic association studies involving these polymorphisms in the Brazilian population.     

T cell activation, apoptosis and cytokine dysregulation in the (co)pathogenesis of HIV and pulmonary tuberculosis (TB)

Immune parameters were compared in four groups of Ugandan subjects: HIV-and HIV+ adult patients with active pulmonary TB (HIV- PTB n = 38; HIV+ PTB n = 28), patients with HIV infection only (n = 26) and PPD+ healthy controls (n = 25). Compared with healthy controls, CD4 and CD8 T cells from patients with HIV and/or PTB expressed more activation markers (HLA-DR, CD38); their CD8 T cells expressed more CD95 (pre-apoptosis) and less CD28 (co-stimulatory receptor). Peripheral blood mononuclear cells (PBMC) of patients with either HIV or PTB were impaired in interferon-gamma (IFN-gamma) production upon antigenic stimulation. PTB (with or without HIV) was characterized by monocytosis, granulocytosis, increased transforming growth factor-beta 1 production and PPD-induced apoptosis. In vivo CD4 T cell depletion, in vitro increased spontaneous CD4 T cell apoptosis and defects in IFN-gamma responses upon mitogenic stimulation were restricted to HIV+ subjects (with or without PTB). Overlapping and distinctive immune alterations, associated with PTB and HIV, might explain mutual unfavourable influences of both diseases.     

CD28 gene polymorphisms and acute cellular rejection after liver transplantation

The co-stimulatory molecule CD28 plays an important role in T-cell-mediated immune response like acute cellular liver transplant rejection. The aim of the retrospective case- control study was to examine whether the single nucleotide polymorphisms (SNPs) rs3116487, rs3116494, and rs3116496 of the CD28 gene are associated with acute cellular liver transplant rejection. The mentioned SNPs were genotyped in 147 liver transplant recipients without acute cellular rejection and 144 liver transplant recipients with acute cellular rejection by real-time endpoint genotyping. The genotype and allele frequencies of the SNPs did not show any significant differences between both groups. Haplotype analyzes of the SNPs also showed no association. Our data suggest that the analyzed SNPs are not major contributors to the susceptibility of acute cellular liver transplant rejection.     

Enhanced Expression of CD80 (B7-1), CD86 (B7-2), and CD40 and Their Ligands CD28 and CD154 in Fulminant Hepatic Failure

To define a possible role for changes in the regulation of antigen presentation in fulminant hepatic failure (FHF), we studied the expression of co-stimulatory molecules CD80 (B7-1), CD86 (B7-2), and CD40 along with their ligands CD28 and CD154. We analyzed the liver tissue from patients with FHF (n = 18), chronic liver disease (n = 30), and acute hepatitis (n = 3) and from normal controls (n = 9) by immunohistochemistry and examined the temporal relationship between CD80/CD86 and CD40 expression and disease in the mouse models of galactosamine-lipopolysaccharide and galactosamine-tumor-necrosis-factor-induced FHF. In human controls, faint CD80/CD86 immunoreactivity was restricted to Kupffer cells, and CD40 expression was expressed on bile ducts, macrophages, and sinusoidal endothelial cells (SECs). In FHF, immunoreactivity for CD80 and CD86 was observed on significantly higher numbers of cells, including SECs. Increased CD80/CD86 expression corresponded to increased numbers of CD28-positive lymphocytes. The expression of CD40 was also clearly elevated on virtually all cell types in FHF. In both murine models, CD40 and CD80/CD86 expression was up-regulated before tissue damage could be detected. Our data suggest that up-regulated expression of co-stimulatory molecules might lead to an excessive antigen presentation in FHF as an early step in the pathogenesis before the onset of tissue damage.     

Investigation of CTLA-4 and CD28 gene polymorphisms in a group of Turkish patients with colorectal cancer

Colorectal cancer (CRC), also called colon cancer or bowel cancer, includes cancerous growths in the colon, rectum and appendix. The immune system is an important defence mechanism against cancer and is often dysfunctional in patients with malignancies. Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and CD28 genes encode receptors that provide negative and positive signals, respectively. Polymorphisms in these genes can affect their functions. In this study, we aimed to investigate the association of cancer with the frequencies and roles of CTLA-4/+49A > G (exon 1) and -318C > T (promoter), and CD28/IVS3 + 17T > C (intron 3 position + 17). These polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 218 Turkish subjects (56 patients with CRC and 162 healthy controls). No statistically significant differences in the genotype distributions of CTLA-4/+49GG (1.8% vs. 6.8%, odds ratio (OR) = 0.250, P = 0.305) and CTLA-4/-318TT (0% vs. 0.6%, OR = 1.006, P = 1.000), and CD28/IVS3 + 17CC (8.9% vs. 3.7%, OR = 0.2411, P = 0.155) between patients with CRC and healthy controls, were observed. We also found that there were no significant differences in the frequencies of CTLA-4/+49G (18.8% vs. 20.1%, OR = 0.920, P = 0.891) and CTLA-4/-318T (7.1% vs. 4.3%, OR = 1.653, P = 0.314), and CD28/IVS3 + 17C alleles (25.9% vs. 19.1%, OR = 1.353, P = 0.139) between two study groups. Present results suggested that CTLA-4 and CD28 gene polymorphisms did not play an important role in Turkish patients with CRC.     

大鼠心脏移植排斥反应过程中外周血CD28、CD40通路相关分子的变化

目的探讨CD28、CD40共刺激通路与排斥反应的关系,同时也为排斥反应的诊断寻找一种新的检测指标。方法采用大鼠异位心脏移植模型,用免疫组化方法动态检测外周血单核细胞（PBMC）CD28、CTLA4、CD40及CD40L分子的表达。结果在0～4级排斥反应中,外周血细胞CD28分子阳性表达率在各组间的差异无统计学意义。外周血细胞表达CTLA4分子的阳性率随排斥反应增强而升高（P〈0.01）。CD40及CD40L在PBMC中的表达强度也随排斥反应的分级逐渐增强（P〈0.01）。结论外周血CTLA4、CD40及CD40L分子的表达与排斥反应有密切关系,动态检测这些分子有助于对排斥反应状态的评价。     

CD40 stimulation induces vincristine resistance via AKT activation and MRP1 expression in a human multiple myeloma cell line

Various co-stimulatory receptors are expressed in multiple myeloma (MM) both in immune microenvironment and in the tumor microenvironment in vivo. In relapsed human MM, these receptors are known to increase cell proliferation and induce conventional drug resistance. However, the mechanism of drug resistance induced via co-stimulatory receptors is poorly understood. In this study, we examined the role of CD40 expressed on MM cell lines. Out of all of the KMS MM cell lines, the KMS28BM cells expressed high levels of the CD40 receptor. When stimulated with anti-CD40 antibody or recombinant human CD40L, the proliferation of KMS28BM cells was increased 1.7 fold. In CD40-stimulated KMS28BM cells, signaling via the AKT pathway caused an increase in the expression of multidrug resistance-associated gene 1 (MRP1) and IL-6 by 2.2 fold and 30 fold, respectively, but not the MDR1 gene. Furthermore, CD40-stimulated KMS28BM cells were observed to be substantially resistant to the anticancer drug vincristine, and when cells were treated with the MRP1 specific inhibitor, MK-571, drug resistance was decreased. We also found that CD40-stimulated, MRP1-expressing KMS28BM cells significantly increased calcein efflux, and calcein efflux was inhibited through treatment with MK-571. Therefore, blocking CD40 and inhibiting MRP1 are potential targets to treat CD40-induced drug resistance in multiple myeloma.     

GD患者外周血CD4+CD28-T细胞亚群的表型特征及临床意义

检测Graves病(GD)患者外周血CD4~+CD28-T细胞水平及其表面CD45RO/CD45RA及ICOS的表达,探讨CD4~+ CD28-T细胞亚群在GD免疫致病机制中的作用。采用三色荧光抗体染色及流式细胞术检测了42例初发GD患者和30例健康者外周血中CD4~+CD28-T细胞的百分率及其表面CD45RO/CD45RA和ICOS表达水平,同时检测其甲状腺功能并进行相关性分析。结果GD患者外周血中CD4~+CD28-T细胞百分率明显高于健康对照组,并高表达ICOS分子,与FT3水平显著正相关;与健康对照组相比,GD患者CD4~+CD28~-CD45RO~+T细胞百分率也显著增高,而CD4~+CD28~-CD45RA~+T细胞呈下降趋势,FT3、FT4水平与CD4~+CD28-T细胞表面CD45RO的表达率呈正相关,而FT3水平与CD45RA表达呈负相关。结论GD患者外周血CD4~+CD28~-T细胞异常增高,表面高表达ICOS分子,具有记忆性细胞的表型特征,与甲状腺功能异常有一定的相关性,CD4~+CD28-T细胞可能是参与GD免疫病理反应的自身反应性T细胞。     

CD28/CTLA-4 and CD80/CD86 costimulatory molecules are mainly involved in acceptance or rejection of human liver transplant

CD28/CTLA-4 interactions with their specific B7-ligands (CD80 and CD86) have decisive roles in antigenic and allogenic responses. Recently, experimental transplant studies demonstrated that donor-specific tolerance is achieved by blocking these interactions. The present study analyzes the expression of these co-stimulatory molecules in peripheral blood cells from 74 liver recipients and in 16 liver biopsies, which were classified into acute-rejection (AR, n = 27) and nonacute-rejection (NAR, n = 47) groups, as well as their influence on the in vitro response of in vivo allosensitized cells. The results clearly indicate that in human liver transplant too, B7 and CD28/CTLA-4 expression on B and CD4(+) peripheral lymphocytes respectively, contributes to graft acceptance or rejection, and appears to be of crucial importance in modulating the host alloresponse and specific-CTL generation. In the NAR-group, costimulatory molecule expression remained at basal levels after transplant, whereas in the AR-group these molecules were significantly upregulated on days of AR. CTLA-4 was observed in the infiltrating lymphocytes in most of the biopsies, but CD80 or CD86 were not. Moreover, specific cytotoxicity from the in vivo primed cells was clearly suppressed in the NAR-patients with low co-stimulatory molecule expression, whereas this activity was not modified but rather stimulated in the AR-group. Together, these findings indicate that intervention of CD28/CTLA-4/B7 signaling could be therapeutically useful in clinical transplantation.