Cellular Immune Failure in Acute Hepatitis C

本项目的目的是验证丙型肝炎病毒（HCV）感染持续存在的假设，由于CD 4依赖性机制在从急性期向慢性期的转变过程中抑制了CD 4 T细胞介导的抗病毒反应的发展。在上一个资助期间，我们已经开发了一种基础设施，从急性感染个体中获得大量的外周血单核细胞（PBMC），并使用覆盖整个HCV多聚蛋白的重叠肽来表征IFN γ介导的免疫应答。大多数受试者对多个表位有反应，峰值识别在6 然后在接下来的12-18个月内下降。尽管进行了氨基酸替换，但在前6个月后未检测到新的特异性。T细胞表位中的氨基酸替换经常代表逃逸突变体，并且大多数表位发展氨基酸替换。因此，我们建议研究急性和慢性感染之间的过渡期间的细胞免疫失败的机制。目的1：确定急性HCV感染者外周血单个核细胞（PBMC）中CD 8 + T淋巴细胞衰竭的分子标志物。我们将确定反应的时间和广度，测量CDS表型和成熟的细胞表面和细胞内标志物。我们将把这些发现与从一组特征明确的志愿者肝脏中获得的淋巴细胞的反应联系起来，以评估 划分目的2：明确CD 4 T细胞在调节CD 8 T细胞对急性HCV感染应答中的作用。将研究CD 4细胞的数量、表型和区室化。测量将包括TH 1/TH 2细胞因子表达、表型和调节的细胞表面标志物，以及这些标志物与目的1中确定的CDS功能的时间关系。拟定的研究将与一个充分表征的前瞻性活跃注射吸毒者队列（见临床核心）具有协同作用，还将从中获得临床、组织学和病毒学信息。

The purpose of this project is to test the hypothesis that hepatitis C virus (HCV) infection persists due to arrested development of CDS T cell-mediated antiviral responses during the ransition from acute to chronic phase by CD4 dependent mechanisms. During the previous funding period we have developed an infrastructure to obtain large numbers of peripheral blood mononuclear cells (PBMC) from acutely-infected individuals, and used overlapping peptides encompassing the entire HCV polyprotein to characterize IFNgamma-mediated immune responses. Most subjects responded to multiple epitopes, with peak recognition around 6 months then decreasing during the following 12-18 months. New specificities were not detected after the first 6 months, despite ongoing amino acid replacements. Amino acid replacements in T cell epitopes frequently represent escape mutants, and most epitopes develop amino acid replacements. We therefore propose to investigate the mechanisms of cellular immune failure during the transition between acute and chronic infection. Aim 1: To define molecular markers of CD8+ T lymphocyte failure in PBMC from persons with acute HCV infection. We will determine the timing and breadth of response, measure cell-surface and intracellular markers of CDS phenotype and maturation. We will correlate these findings with responses in lymphocytes obtained from livers in a well-characterized subset of volunteers to assess the degree of compartmentalization. Aim 2: To define the role of CD4 T cells in modulating CDS T cell responses to acute HCV infection. The number, phenotype, and compartmentalization of CD4 cells will be investigated. Measures will include TH1/TH2 cytokine expression, cell surface markers of phenotype and regulation, and the temporal relationship of these markers versus CDS function determined in aim 1. The proposed studies will be synergistic with a well-characterized prospective cohort of active injection drug users (see clinical core) from whom clinical, histologic, and virologic information will also be obtained.