Thymectomy and Immunity in Congenital Heart Disease

描述（由申请人提供）：在儿童早期免疫成熟期间胸腺切除术的长期影响尚未被调查。一群患有先天性心脏病的儿童和年轻人正在形成，他们在生命早期进行了偶然的胸腺切除术。目前，在外科实践中，对于接受心脏手术的幼儿切除胸腺或保留胸腺尚无共识。从历史上看，胸腺被认为在儿童时期开始退化，到成年时无功能，因此在心胸外科手术中胸腺切除术的常规做法没有禁忌症。然而，较新的研究技术已经证明了胸腺功能在成年期的活性，并揭示了胸腺功能在癌症化疗后免疫重建和实体器官移植后诱导同种异体移植耐受的必要性。我们假设在婴儿期的心胸外科手术中偶然的胸腺切除术会导致细胞免疫系统的长期变化。基于先前的证据和初步数据，我们建议对患有先天性心脏病的不同种族的儿童和年轻人进行回顾性和前瞻性纵向研究，以确定婴儿胸腺切除术对外周血淋巴细胞池和细胞免疫功能的影响。在K08发展规划的背景下，具体目标如下：

DESCRIPTION (provided by applicant): The long term impact of thymectomy during the period of immunologic maturation in early childhood has not been investigated. A cohort of children and young adults with congenital heart disease is forming in whom incidental thymectomy was performed early in life. There is currently no consensus in surgical practice regarding excising or sparing the thymus in young children undergoing cardiac surgery. Historically the thymus was thought to begin involution in childhood and to be non-functional by adulthood, thus presenting no contraindication to the routine practice of thymectomy during cardiothoracic surgery. Newer investigative techniques, however, have allowed demonstration of thymic activity well into adulthood and revealed the necessity of thymic function for immune reconstitution following cancer chemotherapy and for induction of allograft tolerance following solid organ transplantation. We hypothesize that incidental thymectomy during cardiothoracic surgery in infancy causes long term changes in the cellular immune system. Based on previous evidence and preliminary data we propose both retrospective and prospective longitudinal studies in an ethnically diverse population of children and young adults with congenital heart disease to determine the impact of infant thymectomy on peripheral lymphocyte pools and measures of cellular immune function. In the context of K08 program of development, the specific aims are as follows: Aim 1: To measure effects of thymectomy on the generation and maintenance of the peripheral T lymphocyte populations. We will determine the size of key lymphocyte populations and examine parameters of premature immune senescence. Aim 2: To measure effects of thymectomy on cellular and humoral immunity and T cell receptor diversity. Responsiveness to childhood vaccines will be evaluated and the breadth of the effector T cell repertoire will be measured. These studies will provide the investigator with experience which will be applied to future investigations of immune dysregulation in the context of cardiac transplantation in children.