Pathogenic T-cell responses in patients with autoimmune thrombocytopenic purpura

Autoimmune thrombocytopenic purpura (AITP) is a bleeding disorder in which autoantibodies are directed against an individual's own platelets, leading to enhanced clearance through Fc receptor (R)-mediated phagocytosis by macrophages residing in the reticuloendothelial system, particularly in the spleen. This review surveys the recent current literature and updates our understanding of the cell-mediated immunology of AITP. It will focus on the relationship between T-cell reactivities and cytokine profiles in patients with AITP. Understanding these cellular immune aspects of AITP is vital for developing antigen-specific immunotherapies to treat the disease.     

Misdiagnosis of chronic thrombocytopenia in childhood

PURPOSE: Children ultimately diagnosed with nonimmune chronic thrombocytopenia are often referred to pediatric hematology clinics with a provisional diagnosis of autoimmune thrombocytopenic purpura (AITP). The authors' aim was to establish in these patients the features characterizing the mechanism of thrombocytopenia. PATIENTS AND METHODS: The authors performed a retrospective review of the case records of seven children (three boys and four girls, aged 5 months to 7 years) with misdiagnosed chronic AITP referred to a single pediatric hematology center between 1990 and 2000. RESULTS: In the seven children, the suspected diagnosis on referral was AITP and the final diagnosis was inherited thrombocytopenia. Abnormalities of platelets and/or leukocyte morphology were present in all of them. Other features suggestive of inherited thrombocytopenia included a history of familial thrombocytopenia (2/7), failure of steroids and/or intravenous immunoglobulins to raise the platelet count to normal levels (5/7), and moderate increase of Indium-111 platelet turnover in the two patients tested. Platelet-associated IgG (PaIgG) was above the normal threshold in the four children tested; the direct monoclonal antibody immobilization of platelet antigens (MAIPA) test was negative in the four children tested and the serum test was positive in two boys. Bone marrow examination revealed either a normal (4/7) or an elevated (3/7) number of megakaryocytes. CONCLUSIONS: Family history and blood cell morphology analysis in experienced hands are the first steps in discriminating AITP from inherited thrombocytopenia in children with isolated chronic thrombocytopenia. In contrast, bone marrow examination and search for specific autoantibodies using the MAIPA test are of little help. An isotopic platelet life span study, when available, should be performed before considering splenectomy to exclude the diagnosis of inherited thrombocytopenia, especially when steroids and/or IgG IV administration failed to raise the platelet count.     

急性特发性血小板减少性紫癜患儿外周血T细胞蛋白激酶C活性的分析

目的探讨急性特发性血小板减少性紫癜(acuteidiopathicthrombocytopenicpurpura,AITP)患儿外周血T细胞蛋白激酶C(proteinkinaseC,PKC)的活性变化及其与T细胞活化和血小板减少程度之间的关系。方法无菌采集35例急性ITP患儿及30例正常儿童外周抗凝血,用T淋巴细胞分离富集柱法分离纯化T细胞,分别用非同位素标记法检测T细胞PKC的活性变化,用流式细胞仪检测T细胞活化标志FasL蛋白的表达,血细胞计数仪计数血小板。结果急性ITP患儿T细胞PKC的总活性与正常儿童相比明显增强[(0.97±0.21)nmol/(min.ml)、(0.55±0.13)nmol/(min.ml),P<0.01],T细胞活化标志FasL蛋白表达与正常儿童比较显著升高[ThFasL:(32.7±3.4)%、(14.7±4.2)%;TcFasL:(17.3±9.7)%、(11.6±8.5)%,P<0.01],并且T细胞PKC的活性变化与ThFasL、TcFasL的表达均呈显著正相关(r1=0.68,r2=0.53,P<0.05),与血小板计数呈显著负相关(r=-0.75,P<0.05)。结论急性ITP患儿外周血PKC活性增强可引起患儿T细胞的活化,活性T细胞增多可导致患儿血小板大量损伤,并引起临床症状,提示PKC信号传导在急性ITP的免疫病理机制中发挥重要作用。     

特发性血小板减少性紫癜患儿骨髓巨核细胞表面CXCR4受体及其配体的研究

目的 探讨急性特发性血小板减少性紫癜(AITP)患儿骨髓巨核细胞表面CXCR4受体表达改变及其配体——基质细胞来源性因子1α(SDF-1α)水平变化的意义。方法 收集28例AITP患儿及12例正常对照儿童的骨髓;用Percoll密度梯度及免疫磁珠法分离骨髓巨核细胞;采用ABC免疫细胞化学染色法检测巨核细胞受体CXCR4的表达水平;ELISA法检测骨髓上清液SDF-1α的含量;用统计学分析软件包SPSS10．0对实验数据进行统计学分析。结果 28例初治AITP患儿骨髓CXCR4与SDF-1α水平均明显低于正常对照组;28例中10例大剂量丙种球蛋白(简称丙球)敏感组患儿治疗后CXCR4与SDF-1α水平均明显高于治疗前;另外28例中6例对丙球不敏感的患儿治疗前巨核细胞表面CXCR4的表达明显低于丙球敏感组治疗前患儿。结论 初治AITP患儿骨髓巨核细胞成熟障碍与血小板生成障碍可能与骨髓CXCR4／SDF-1α体系水平下降有关;而丙球治疗AITP的作用机理可能与增强骨髓CXCR4／SDF-1α体系表达有关;巨核细胞表面CXCR4表达水平可能在预测丙球的治疗效果方面有意义。     

婴儿急性特发性血小板减少性紫癜与巨细胞病毒感染的相关性探讨

目的探讨婴儿急性特发性血小板减少性紫癜(AITP)与巨细胞病毒(CMV)感染的相关性、临床特点及治疗。方法对于AITP患者,应用ELESA方法测CMVIgG、IgM,对仅CMVIgG阳性者,再予CMVDNAPCR检测,同时予肝功能检测。对于CMVIgG或CMVDNAPCR阳性而无肝功能损害,均予地塞米松(Dex)+静注人血丙球(IVIG)常规治疗,而对同时有肝功能损害者分析予Dex+IVIG+阿托莫兰或Dex+IVIG+阿托莫兰+更昔洛韦(GCV)治疗。结果仅CMV感染而无肝功能损害与非CMV感染的AITP患者经正规治疗后,两组血小板升至正常时间差异无显著性,而肝功能异常时,两组血小板升至正常及肝功能恢复时间有显著性差异。结论婴儿AITP与CMV感染密切相关,若合并有其它脏器损害需联合应用GCV治疗,否则只需常规治疗。     

Autoantibodies and CD5+ B cells in childhood onset immune thrombocytopenic purpura

We evaluated platelet associated immunoglobulin (PaIg) G, PaIgM, platelet associated autoantibodies to platelet glycoprotein IIb/IIIa (Pa-GPIIb/IIIa), the percentage of CD5⁺ B cells and the amount of platelet-bound anti-GPIIb/IIIa monoclonal antibody (mAb) in the peripheral blood of 29 patients with childhood onset chronic immune thrombocytopenic purpura (c-ITP). The percentage of CD5⁺ B cells ranged from 2 to 8% (4.7 ± 2.0) in control patients and 1 to 18% (6.2 ± 4.2) in the ITP patients. There was no overall significant difference between the two groups, but the percentage of CD5⁺ B cells in six of the ITP patients was higher than the mean + 2 s.d. of the controls. There was a significant correlation between the percentage of CD5⁺ B cells and PaIgM (y = 1.73x + 13.4, r = 0.40, P < 0.05). This finding is the basis for the speculation that CD5⁺ B cells may play an important role in the production of PaIgM in vivo. There was no correlation between the amounts of PaIgG and Pa-GPIIb/IIIa. This suggests that the amount of PaIgG does not accurately reflect of the amount of Pa-GPIIb/IIIa. Furthermore, we have demonstrated that autoantibodies to GPIIb/IIIa are directed to more than one epitope.     

Neonatal and infant beta cell hormone concentrations in relation to type 1 diabetes risk

Type 1 diabetes is preceded by the appearance of islet autoantibodies. Seroconversion to islet autoantibodies is greatest around 1 yr of age and is more frequent in children born to fathers with type 1 diabetes as compared to children born to mothers with type 1 diabetes. Here we asked whether changes in beta‐cell function in the neonate and infant reflect variations in the incidence of islet autoantibody seroconversion. Insulin, proinsulin, and c‐peptide concentrations were measured in sequential samples taken from birth to age 2 yr in 103 children who had a first degree relative with type 1 diabetes and who had been followed for islet autoantibody seroconversion. Serum insulin and proinsulin concentrations were highest at birth declining by age 3 months and stable thereafter until age 2 yr. C‐peptide concentrations, proinsulin/insulin, and proinsulin/c‐peptide ratios were stable from age 3 months. No differences were observed between children who developed islet autoantibodies and children who remained islet autoantibody negative. Children born to a mother with type 1 diabetes had higher birth concentrations of insulin (p = 0.005) and proinsulin (p = 0.014) as compared with children of non‐diabetic mothers. Increased insulin concentrations in children of type 1 diabetes mothers persisted until age 6 months. In conclusion, we could not relate excursions in beta‐cell hormones to autoantibody development, but suggest that the higher exposure to insulin and proinsulin in neonates born to mothers with type 1 diabetes may be linked to the relative protection against islet autoantibody seroconversion observed in these children.     

Mechanisms of action of therapeutics in idiopathic thrombocytopenic purpura

Idiopathic thrombocytopenic purpura (ITP) is a common immune disorder caused by platelet-reactive autoantibodies. Antibody-coated platelets are cleared more rapidly from the circulation, often in the spleen, than they can be replaced by compensatory stimulation of platelet production in the bone marrow. In some patients, platelet production is depressed as well. ITP in adults does not generally remit spontaneously, and most patients require treatment to prevent bleeding at one time or another. Therapy with corticosteroids, danazol, intravenous immune globulin, anti-D antibody, and several other agents inhibits clearance of the antibody-coated platelets but is rarely curative. Most patients will sustain a hemostatic response after splenectomy, although relapses may occur at any time. Patients may be more responsive to these same modalities after splenectomy, but treatment with an immunosuppressant that inhibits T- and B-cell function and cooperation, including azathioprine, cyclophosphamide, cyclosporine, mycophenolate mofetil, or anti-CD20, may be required. Antiviral therapy is useful in patients with HIV or hepatitis C infection, but no consensus has been reached as to the efficacy of antibiotics to eradicate Helicobacter pylori. Promising results have been seen in several patients treated with a modified thrombopoietin. It may be possible to design therapeutics that exploit the apparent restricted immunoglobulin gene usage by antiplatelet antibodies, perhaps in the form of engineered anti-idiotypic antibodies or other compounds that specifically target autoantibody-producing B cells. Rationale therapy awaits a more thorough understanding of autoantibody production.     

特发性血小板减少性紫癜患儿血小板生成素及其受体基因转录水 …

目的 探讨急性特发性血小板减少性减少性紫癜（ＡＴＴＰ）患儿血小板生成素（ＴＰＯ）及血小板ＴＰＯ受体ｃ－ＭＰＬ ｍＲＮＡ基因转化水平变化的意义。方法 采用ＥＬＩＳＡ法检测血清ＴＰＯ、血小板相关抗体（ＰＡＩｇＧ）水平;半定量ＲＴ－ＰＣＲ法检测外周血血小板ｃ－ＭＰＬ ｍＲＮＡ的相对量。结果 ＡＴＴＰ患儿初治时血浆ＴＰＯ水平增高,血小板ｃ－ＭＯＬ ｍＲＮＡ较低;以大剂量甲基强的松龙冲击治疗后,位随血小板计     

Cytokines in idiopathic thrombocytopenic purpura (ITP)

Most research in idiopathic thrombocytopenic purpura (ITP) has focused on characterization of the autoantibodies directed against platelet antigens resulting in enhanced platelet elimination by macrophages. This report summarizes the current knowledge of cytokine pattern found in individuals with ITP. Serum assessment has demonstrated increased levels of interleukin (IL)-2 and interferon-gamma (IFN-7), while IL-4 was significantly decreased. In addition, thrombopoietin (TPO) has been found in normal levels while IL-11 has been reported to be elevated. These data indicate that ITP is associated with a Th1 type of T helper cytokine response, while that of type Th2 is downregulated. Initially, megakaryocytes are found at normal levels in bone-marrow aspirates, explaining the unchanged production of TPO. The increase in IL-11 may be reflected by the increased number of platelets being produced per megakaryocyte. However, there is little information on these events in immunocompetent sites such as bone marrow, spleen and lymph nodes.     

Prevalence and Clinical Significance of Antithyroid Antibodies in Children with Immune Thrombocytopenic Purpura

Background and objective: To determine the prevalence and the clinical significance of thyroid autoantibodies and their influence on treatment response in children with idiopathic thrombocytopenic purpura (ITP). Patient and Method: We retrospectively analyzed the antithyroglobulin (anti-TG) and antithyroid peroxidase (anti-TPO) antibodies from the records of 151 ITP patients who were admitted to the Pediatric Hematology Department of Gaziantep University between 2009 and 2012. Results: Anti-TPO and/or anti-TG was found positive in 38 (36.8%) of 103 patients whose thyroid autoantibody levels were measured. The comparison of positivity ratios of autoantibodies between acute and chronic ITP patients showed no significant difference. However, the separate comparison of each group of ITP patients with control group showed significantly high positivity ratios of autoantibodies in ITP patients. The initial mean platelet count of anti-TPO positive patients at diagnosis was significantly less than that of the negative patients (P = .008). One month after treatment, platelet count of anti-TPO positive patients was significantly less than that of the negative patients (P = .01). Moreover, the mean platelet counts of anti-TPO positive patients were significantly less than those of the negative patients after intravenous immunoglobulin treatment (P < .001). Conclusion: We demonstrated that the thyroid-autoimmune-diseases-related autoantibodies are frequently found in childhood ITP. Although no recommendation is found in international guidelines regarding screening for thyroid autoantibodies in patients with ITP, in view of the high incidence of antithyroid antibodies and their potential negative effect on treatment response, screening these patients for such antibodies would be recommended.     

Antiplatelet antibodies in chronic adult immune thrombocytopenic purpura: assays and epitopes

Chronic immune thrombocytopenic purpura (ITP) is an autoimmune disorder characterized by thrombocytopenia due to autoantibody-induced platelet destruction. The majority of these autoantibodies are directed to epitopes on either glycoprotein (GP) IIb-IIIa or GPIb-IX. The newer antigen-specific autoantibody assays are capable of detecting both platelet-associated and plasma autoantibodies and have a definite role in the diagnosis of immune thrombocytopenia. A positive assay provides strong evidence for the presence of immune thrombocytopenia both in chronic ITP and in other diseases where immune thrombocytopenia may occur, such as collagen vascular disease and lymphoproliferative disorders. However, a negative assay does not rule out the presence of ITP. Somewhat concerning is the large number of patients who have negative assays. Several possible explanations for these observations are discussed. Recent studies have localized some ITP autoepitopes to specific regions of GPIIb-IIIa and GPIb-IX. Most autoepitopes on GPIIb-IIIa are conformational, in view of their dependence on divalent cations, and are localized to the N-terminal portion of GPIIb, while the GPIb-IX autoepitopes that have been identified are localized to GPIb amino acids 333-341.     

Effect of immunotherapy on autoimmune parameters in children with atopic asthma

There is an increased rate of reported autoantibody production in patients with atopic and nonatopic asthma. The possibility of generating autoantibodies after the induction of immunotherapy can be explained by several mechanisms. One of these is immune deviation from TH2 to TH1 response by the effect of immunotherapy in favor of unregulated response to self-antigens. The other theory is a possible antigenic mimicry enabling autoantibody formation in these patients, Sixty-three atopic asthmatic children were included in the study. The patients were divided into three groups: Group I: patients with atopic bronchial asthma without immunotherapy: Group II: patients receiving immunotherapy for a maximum of 3 years; Group III: patients receiving immunotherapy for 4-5 years. The autoantibodies examined in the study population were anti-nuclear antibody, anti-double stranded DNA, rheumatoid factor, liver-kidney microsomal antibody, anti-mitochondrial antibody, anti-thyroglobulin and anti-microsomal antibody, anti-Smith antibody and lupus anticoagulant. An overall incidence of 17.5% autoantibody positivity was observed in patients, with no statistical significance between the treatment groups. IgG levels were significantly elevated in Group III when compared with Group I. Based on these findings it is suggested, in accordance with other studies, that long-term immunotherapy in the pediatric age group does not cause a significant autoantibody formation other than the overall increased incidence that occurs in asthmatic patients.     

应用表面增强激光解吸电离飞行时间质谱筛选急性特发性血小板减少性紫癜患儿血清生物标志物

目的 应用表面增强激光解吸电离飞行时间质谱(SELDI-TOF-MS) 技术结合蛋白芯片检测并筛选急性血小板减少性紫癜(AITP)早期诊断、病情变化监测及判断预后的血清蛋白质标志物,建立AITP诊断模型,并验证在血清蛋白质组水平,创立AITP的分子诊断新方法.方法 应用SELDI-TOF-MS检测结合在蛋白质芯片上的血清蛋白质,获得35例AITP、35例健康对照者血清蛋白表达指纹图谱,并用Biomarker Wizard软件对数据进行分析,建立人工神经网络诊断模型.结果 在分子质量/电荷比值(质荷比,M/E)为2 000～20 000,AITP组与健康对照组之间差异有统计学意义(P<0.01)的蛋白质峰有29个,其中高表达的蛋白质峰7个,低表达的蛋白质峰22个,从分析的结果看最有意义的蛋白质为质荷比为4 109.23、5 521.35 的蛋白质,可以将其作为AITP的血清生物标志物;在蛋白质库中搜索与上述M/E值相对应的蛋白质,M/E为4 109.23的标志物是核蛋白体large subunit,M/E为 5 521.35 的标志物在蛋白质库中未发现.应用其血清标志物进入人工神经网络组合的诊断模型,将AITP组与健康儿童准确分组,敏感度为95%,特异度为90%.结论 1.M/E比为4 109.23、5 521.35 的蛋白质组合的诊断模型能将AITP与健康儿童完全准确地分开,提示该蛋白质可能是AITP的血清生物标志物;其中M/E为5 521.35的蛋白质可能是新的蛋白质.2.SELDI-TOF-MS技术是寻找疾病相关性蛋白质的有效工具.     

Analysis of transmembrane signalling and T cell defects associated with idiopathic thrombocytopenic purpura (ITP)

Adult chronic idiopathic thrombocytopenic purpura (ITP) is an autoimmune disease characterized by production of autoreactive antibodies to platelet antigens. It is now becoming clear that autoantibody production, in general, is regulated by T helper (Th) cells. Several recent studies have examined potential defects in T cell function in this disease and have demonstrated that patients with ITP possess abnormal lymphocyte activation and Th₁/Th₂-mediated cytokine production. Although the underlying cause(s) of aberrant T cell function in this disease are not known, studies from other models of autoimmune disease indicate that defects in T cell transmembrane signalling can be causally linked to abnormal T cell activation and cytokine production. This review will present some of the major T cell signalling pathways and discuss how altered T cell signalling may be linked to autoimmunity with an emphasis on ITP. Recent preliminary findings of a potential defect in the signal transduction apparatus in lymphocytes from three patients with ITP will also be presented.     

特发性血小板减少性紫癜实验室特点与临床意义

目的 研究特发性血小板减少性紫癜实验特点与临床诊断、治疗效果的关系。方法对57例ITP患儿和15例健康儿童进行血小板计数(BPC)、平均血小板体积(MPV)、血小板分布宽度(PDW)和血小板压积(PCT)测定;对57例ITP患儿用酶联免疫法(ELISA)检测血小板相关抗体(PAIgG、PAIgM);用聚合酶链反应(PCR)检测VB19、EBV、CMV;42例患儿接受地塞米松联合丙种球蛋白治疗。结果①治疗前,ITP组的BPC、PCT明显降低,与对照组比较有统计学意义(P<0.05),急性ITP(AITP)的PDW、MPV明显增加(P<0.05),慢性ITP(CITP)组PDW、MPV无明显变化(P>0.05)。②治疗后,AITP组PDW、MPV与对照组比较无明显变化(P>0.05);CITP组BPC、PCT仍明显减少,MPV呈明显增大(P<0.05),PDW呈分布宽度差异性变大。③丙种球蛋白治疗效果与血小板相关抗体(PAIgG、PAIgM)的表达有统计学意(X2值分别为5.03、3.96,P<0.05)。结论 血小板参数可作为ITP的诊断、病情严重程度的判别指标;血小板相关抗体PAIgG和PAIgM的表达对于指导丙种球蛋白临床治疗有一定的意义。     

Autoantibody to complement neoantigens in membranoproliferative glomerulonephritis

With the exception of C3 nephritic factor, autoantibody formation has not been commonly associated with membranoproliferative nephritis (MPGN). We measured autoantibodies (nephritic factors) to the C3 convertases C3bBb (NFa) and C3bBbP (NFt), which result in fast and slow C3 activation, respectively, and to a neoantigen on C1q fixed to a solid phase (spC1q) in sera from 29 patients with MPGN type I, 26 with type II, and 28 with type III. Autoantibody formation was common in all MPGN types. An autoantibody to a C3 convertase neoantigen was identified in more than 75% of the hypocomplementemic MPGN sera tested. Anti-C3bBb (NFa) was present in 81% of patients with MPGN type II but was rarely found in either type I or type III. Anti-C3bBbP (NFt) was common in both MPGN I and III. Anti-spC1q was present in 74% of patients with type I and in 38% and 48% of types II and III MPGN, respectively. Patients with MPGN types I, II, and III had one and two serum autoantibodies detected significantly more frequently than did a group of healthy subjects. The presence of any one autoantibody was not specifically associated with the presence of any other autoantibody. The results indicate that multiple autoantibody formation is common in all MPGN types. MPGN II, and possibly MPGN I, tend to form more specific autoantibodies.     

丙种球蛋白强的松联合治疗急性特发性血小板减少性紫癜近期疗效观察

目的：　探讨丙种球蛋白、强的松联合治疗血小板减少性紫癜(ITP)的近期疗效。方法：　观察组采用蓉生静丙,剂量每日400mg/kg,连用5d,后续用强的松治疗4周;对照组单用强的松4～6周。 结果：　观察组血小板达高峰时间为1～2周,峰值约180×10 9/L,总有效率为86.7%;对照组上述数值分别为4周,116×10 9/L和40% (P<0.05)。结论：　丙种球蛋白、强的松联合治疗ITP明显优于单用强的松组。     

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目的探讨影响小儿急性特发性血小板减少性紫癜(AITP)发展成慢性特发性血小板减少性紫癜(CITP)的危险因素。方法选择2006年5月至2010年4月于广西医科大学一附院诊断AITP住院患儿138例,对患儿临床表现、实验室检查、治疗方案等16个相关因素分别进行单因素成组对照研究。对有意义的单因素,再运用非条件Logistic多因素回归模型分析,以期找到有意义的因素。结果病程(患儿起病至治疗时间)、ORh(D)+型血、用含有大剂量丙种球蛋白的治疗方案、血小板上升正常时间都是影响AITP患儿转为慢性的主要因素,而与发病年龄、治疗初用血小板、血小板开始回升时间、性别、有无前驱显性感染、治疗前血小板数、血小板平均体积、血小板平均分布系数、骨髓巨核细胞数、幼稚巨核细胞数、颗粒型巨核细胞数、有无幼稚淋巴细胞数无关。结论 AITP患儿早期治疗时用有大剂量丙种球蛋白的治疗方案是改善预后的关键,治疗时血小板回升正常时间晚、ORh(D)+血型(相对于A和B血型)是转为慢性的高危因素。     

Development of autoantibodies after pediatric liver transplantation

Dn‐AIH is a long‐term complication after LT. The aim of this study was to analyze the occurrence of autoantibodies in pediatric recipients and the clinical significance. From 1992 to 2008, 96 pediatric LT for non‐autoimmune liver diseases were performed in 94 children in our institution. Serum autoantibodies were checked in 68 subjects (73.9%). A positive autoantibody was defined as titers ≥1:40 for ANA, or ≥1:20 for ASMA, anti‐LKM, and AMA. Autoantibodies were detectable in 51 of 68 patients (75.0%). There was positivity for ANA in 30 patients, ASMA in 32, and AMA in three, while anti‐LKM was all negative. Immunosuppressive treatment with CsA, more than one episode of rejection, and abnormal ALT were risk factors for the development of autoantibodies. The incidence of the development of autoantibodies was 75.0% in pediatric LT cases in this study. ASMA was the most commonly found autoantibody. Autoantibodies may not play a sentinel role for dn‐AIH after LT.