ANERGY, APOPTOSIS AND CD28 IN CD8+ T CELLS DURING AIDS

HIV感染中的效应CD 8 + T细胞负责最初的病毒血症控制，然而，HIV特异性CTL 记忆细胞在疾病进展期间通过未知的机制丢失。我们的数据显示， 含有HIV特异性CD 8 + CD 28 m细胞，其通过单核细胞的共刺激而死亡。此外，我们发现HFV 在体外引起CD 28配体（CD 80和CD 86）的过度表达，诱导CD 28丢失和CD 8+细胞凋亡。 T细胞。这些观察结果表明，CD 8 + T细胞能够成为记忆的基本机制 HIV特异性CTL可在疾病进展过程中选择性丢失。为了研究这个假设，我们提出三个 目标。目的1探讨CD 28下调和细胞凋亡的机制。使用CHO细胞系与 确定水平的共刺激配体，CD 80或CD 86，与纯化的T细胞孵育，我们将评估机制 负责CD 28下调和凋亡。为了研究艾滋病毒感染的重要性，我们将混合 自体HIV感染的巨噬细胞与T细胞，检查巨噬细胞上的CD 80和CD 86表达， 以及细胞接触、巨噬细胞释放的可溶性因子或细胞因子对CD 28下调的影响， CD 8 T细胞的调节和凋亡。由于对CD 28的分子调控知之甚少， 表达，目的2将通过测试NF-κ B的差异结合来检查CD 28启动子的下调。 kBa和/或STAT-6蛋白，这将为预防CD 28丢失提供分子基础。Ann 3将开发 增加HIV中抗原特异性记忆CD 8 + T细胞的潜在治疗方法。使用同种异体抗原作为 模型，我们将调节共刺激，激活条件，时间，信号强度和细胞因子。最 增加记忆性CD 8 + T细胞的有希望的方法将用于来自HIV感染患者的CD 8 + T细胞。 由于CD 8 + T细胞对HIV控制很重要，因此这些研究对免疫系统的发展很重要。 干预策略和疫苗设计。

Effector CD8+ T cells in HIV infection are responsible for initial viremia control, however, HIV-specific CTL memory cells are lost during disease progression by an unknown mechanism. Our data show that HIV+ patients contain HIV-specific CD8+CD28 m cells which die by costimulation via monocytes. hi addition, we found that HFV causes over-expression of the CD28 ligands (CD80 and CD86) in vitro, inducing CD28 loss and apoptosis of CD8+ T cells. These observations suggest a fundamental mechanism whereby CD8+ T cells capable of becoming memory HIV-specific CTL could be selectively lost during disease progression. To study this hypothesis we propose three aims. Aim 1examines mechanisms for CD28 down-regulation and apoptosis. Using mixtures of CHO cell lineswith defined levels of costimulatory ligands, CD80 or CD86, incubated with purified T cells, we will assess mechanisms responsible for CD28 down-regulation and apoptosis. To examine the importance of HIV infection, we will mix autologous HIV-infected macrophages with T cells, examine CD80 and CD86 expression on the macrophages, as well as the effects of cell contact, soluble factors or cytokines released by the macrophages on CD28 down- regulation and apoptosis of the CDS T cells. Because little is known about molecular regulation of CD28 expression, Aim 2 will examine the down-regulation of the CD28 promoter by testing differential binding of NF- kBa and/or STAT-6 proteins, which will provide a molecular basis for prevention of CD28 loss. Ann 3 willdevelop potential therapeutic methods to increase antigen-specific memory CD8+ T cells in HIV. Using alloantigen as a model, we will modulate costimulation, activation conditions, timing, strength of signals, and cytokines. The most promising methods to increase memory CD8+ T cells will be used with CD8+ T cells from HIV-infected patients. Because CD8+ T cells are important for HIV control, these studies are important for development of immune intervention strategies and for vaccine design.