Transplant EBV Disease: Pathogenesis and Immunotherapy

儿童实体器官移植中使用的免疫抑制治疗与EB病毒(EBV)驱动的淋巴增生性疾病的发生有关。(PTLD)近十分之一的儿童心脏移植(TX)受者在TX后7年内会发展为PTLD。有这种并发症的患者的长期结果一直令人失望。90%的病例是由EBV驱动的，几乎所有的肿瘤都来自受体B细胞。大多数人 TX患者的病毒载量持续升高，我们不清楚这些病毒载量是如何建立或维持的，也不清楚持续的病毒载量对无症状携带者意味着什么危险。我们提出了儿童心脏(H)和心肺(H/L)TX受者持续EBV感染的病毒学分析。 匹兹堡儿童医院。在这项研究中，我们计划使用定量聚合酶链式反应和免疫组织化学技术，根据所涉及的B细胞间隔、病毒感染细胞的克隆程度以及病毒启动子的使用和基因表达的模式来表征高和低病毒载量。通过使用现有的样本库，我们将在研究期间添加样本库，以回顾和前瞻性地收集数据，以提供 清楚描述病毒感染导致负载携带者状态和PTLD的过程。T细胞免疫监视受损是慢性高病毒载量和PTLD进展的重要相关因素，对免疫抑制的TX患者中残留应答细胞类型的频率和特异性知之甚少。初步研究表明，T细胞的反应可能从有益的Th1表型向效率较低的Th2表型倾斜。利用HLA四聚体和ELISPOT分析，我们将表征H和H/L TX患者抗EBVCD8T细胞反应的谱系和频率。尽管EBV病患者的护理取得了一些进展，但总体上，尤其是PTLD患者的管理仍然具有极大的挑战性。即使不是很多，也很多 大多数患者将经历减少免疫抑制的临床反应，这是以在这种治疗操作过程中发生叠加排斥反应的潜在代价为代价的。对于H或HTL TX受体，接受这种排斥风险时必须知道排斥反应可能会出现心律失常和猝死。我们将开发使用EBV特异性CTL的过继免疫疗法，作为安全有效的替代方案。 儿童H和H/L TX受体的治疗将进行一期临床试验，以确定儿童胸腔TX受体难治性PTLD、复发性PTLD或症状性EBV病对使用树突状细胞针对特定EBV抗原而产生的CTL的反应。

Immunosuppressive therapies used in pediatric solid organ transplantation are associated with the development of Epstein-Barr virus (EBV) driven lymphoproliferative disease. (PTLD) Almost one in 10 pediatric heart transplant (Tx) recipients will develop PTLD by 7 years after Tx. Long-term outcomes of patients with this complication have been disappointing. Ninety percent of cases are driven by EBV and almost all tumors are of recipient B cell origin. A majority ot Tx patients develop persistently elevated viral loads and we do not have a clear understanding of how these loads are established or maintained, or a clear picture of what dangers persistent viral loads represent to an asymptomatic carder. We propose a virologic analysis of persistent EBV infection in the pediatric heart (H) and heart/lung (H/L) Tx recipients at the Children's Hospital of Pittsburgh. For this study, we plan to use quantitative PCR and immunohistochemical techniques to characterize the high and low viral load in terms of the B cell compartments involved, the degree of clonality of the virus infected cells, and the patterns of viral promoter usage and gene expression. By using an existing specimen bank, to which we will add during the study, data will be collected retrospectively and prospectively to provide a clear picture of the course of virus infection that leads to the load carder state and PTLD. Impaired T cell immune surveillance is an important correlate in progressionto chronic high viral loads and PTLD, and little is known about the residual responder cell types in terms of their frequencies and specificities in immunosuppressed Tx patients. Preliminary work indicates that T cell responses may be skewed away from the beneficial Th1 phenotype towards the less effective Th2 phenotype. Using HLA-tetramer and ELISPOT assays we will characterize the repertoire and frequency of anti-EBV CD8 T cell responses in H and H/L Tx patients. The management of patients with EBV disease, in general, and PTLD in particular remains extremely challenging despite a number of advances in the care of these patients. While many, if not the majority of patients will experience a clinical response to reduction of immune suppression, this is done at the potential cost of developing superimposed rejection during thistherapeutic manipulation. For H or HtL Tx recipients, acceptance of this risk of rejection must come with the knowledge that rejection may present with dysrhythmia and sudden death. We will develop adoptive immunotherapy with EBV-specific CTLs as a safe and effective alternative therapy for pediatric H and H/L Tx recipients. A phase 1 clinical trial will be conducted to determine the response of fractory PTLD, relapsed PTLD, or symptomatic EBV disease in pediatric thoracic Tx recipients to infusions of CTLs raised against specific EBV antigens using dendritic cells.