Immune reconstitution to Aspergillus

描述(申请人提供)：在异基因造血干细胞(HCT)受者中，侵袭性曲霉病(IA)的年发病率从10%到15%不等，死亡率约为80%；因此，这种感染已成为HCT后感染相关死亡的主要原因。感染现在主要发生在同种异体红细胞移植过程的晚期，即中性粒细胞植入之后。流行病学与最近的认识是一致的，即动物模型的有效免疫需要强大的CD4+T辅助细胞1型(Th1)反应。然而，还没有进行大型研究来评估曲霉菌特异性的免疫重建。我们已经开发了测量细胞对曲霉菌抗原反应的方法，并在健康志愿者中展示了可重复性的可变反应。我们提出了一项纵向免疫重建研究，以评估CD4+T细胞重建对异基因HCT后晚期IA的保护作用这一假说，包括供者转移免疫在内的多种因素潜在地影响免疫重建。具体目标是：1.确定重组细胞免疫是否预测IA的风险和结果。患者将参加一项纵向研究，以评估重组细胞数量(DC1、DC2、T细胞亚型、NK细胞和B细胞)和对烟曲霉菌丝抗原的功能反应是否预测IA的风险和结果。在目标2中，研究将确定反应性CD4+T细胞的不同频率和细胞因子模式在健康捐赠者中的意义。将对捐献者的反应进行评估，以检验以下假设：健康人产生干扰素-伽马的CD+T细胞的低频率与MHC等位基因相关，可能包括特定的II类单倍型和/或III类区域(肿瘤坏死因子-α基因)的多态性(S)。将评估捐赠者反应对受者重建的影响。AIM 3中的研究将鉴定呈递给健康人类CD4+T细胞的烟曲霉菌抗原。曲霉菌特异性的CD4+T细胞克隆将通过菌丝抗原的顺序刺激从健康受试者中产生。经典的人类白细胞抗原限制性CD4+克隆将被用来筛选烟曲霉菌cDNA池文库，并通过顺序筛选识别单个T细胞抗原。这项研究的目的是明确移植后对曲霉菌的免疫保护机制。这些信息将对制定预防和治疗免疫受损人群真菌感染的策略很有价值。

DESCRIPTION (provided by applicant): The annual incidence of invasive aspergillosis (IA) ranges from 10 to15% in allogeneic hematopoietic stem cell (HCT) recipients, with mortality approximating 80%; as such, this infection has become a prominent cause of infection-related death after HCT. Infection now occurs primarily late in the course of allogeneic HCT, after neutrophil engraftment. Epidemiology is consistent with the recent recognition that effective immunity in animal models requires robust CD4+ T helper type-1 (Th1) responses. However, no large studies have been performed to evaluate Aspergillus-specific immune reconstitution. We have developed the methods to measure cellular responses to Aspergillus antigens, and demonstrated reproducibly variable responses in healthy volunteers. We propose a longitudinal immune-reconstitution study to evaluate the hypothesis that CD4+ T cell reconstitution is important to protect from IA late after allogeneic HCT, with multiple factors, including donor transferred immunity, potentially impacting immune reconstitution. Specific aims will be to: 1. Determine if reconstituted cellular immunity predicts risks for, and outcomes of IA. Patients will be enrolled in a longitudinal study to evaluate whether reconstituted cell numbers (DC1, DC2, T cell subtypes, NK cells and B cells) and functional responses to A. fumigatus hyphal antigen predict risks for, and outcomes of IA. In Aim 2, studies will determine the significance of variable frequencies of reactive CD4+ T cells and cytokine patterns in healthy donors. Donor responses will be evaluated to test the hypothesis that low frequencies of IFN-gamma producing CD4+ T cells in healthy people are associated with MHC alleles, potentially including specific Class II haplotypes and/or polymorphism(s) in the Class III region (TNF-alpha gene). The impact of donor responses on recipient reconstitution will be evaluated. Studies in Aim 3 will identify Aspergillus fumigatus antigens presented to healthy human CD4+ T cells. Aspergillus-specific CD4+ T cell clones will be generated from healthy subjects by sequential stimulation with hyphal antigens. Classical HLA-restricted CD4+ clones will be used to screen pooled libraries of A. fumigatus cDNA, with sequential screens identifying individual T-cell antigens. This study will be performed with the goal of defining the mechanisms of post-transplant immune protection against Aspergillus species. This information will be valuable for development of strategies to prevent and treat fungal infections in immunocompromised people.