CD4 T CELL ANERGY IN MURINE AIDS

小鼠艾滋病中的 CD4 T 细胞无能

基本信息

批准号：
2882414
负责人：
GIRIJA MURALIDHAR
金额：
$ 14.79万
依托单位：
SIDNEY KIMMEL CANCER CENTER
依托单位国家：
美国
项目类别：
财政年份：
1994
资助国家：
美国
起止时间：
1994-07-01 至 2001-02-28
项目状态：
已结题

项目摘要

BM5, a mixture of retroviruses induces a fatal immunodeficiency syndrome when injected into C57BL/6 mice. The most interesting feature of this disease is an absolute requirement for CD4 T cells for disease induction and progression. Interestingly, as the disease sets in, CD4 T cells become completely unresponsive to polyclonal and antigen-specific stimulations. Moreover, BM5 retroviral mixture appears to either encode or stimulate an endogenous superantigen which deletes Vbeta5.2 positive CD4 T cells in the spleen and lymph nodes of infected animals. This model presents an ideal in vivo system to study CD4 T cells that are rendered anergic by retroviral infection because entire CD4 T cell population representing various Vbeta TCRs is anergic and is not restricted to a few subsets of CD4 T cells. We will take advantage of such a system to.study the process of anergy as CD4 T cells steadily lose their capacity to proliferate or synthesize cytokines in response to various stimuli. The initial approach is to pinpoint the defective steps in the cascade of reactions that follow TCR stimulation. We will test the possibility that there is an altered tyrosine phosphorylation of substrates since it is the first step in signal transduction and the involvement of tyrosine kinases such as p56 1ck, p59 fyn and phosphatases like CD45 in anergy. Other steps in signal transduction namely, phosphoinositide hydrolysis and subsequent CA++ release and activation of PKC will be evaluated. Next, we will monitor the expression of various costimulatory molecules on anergic and normal CD4 T cells. In order to assess the role of costimulatory molecules in inducing lymphokine gene expression, we will coculture anergic CD4 T cells with anti-CD28 or provide APCs that have high expression of B7 and study the effects on IL-2 and IL-4 gene transcription. In most superantigen induced anergy systems, anergic cells undergo apoptosis when they are stimulated via the TCR. Apoptosis is blocked in cells with elevated expression of bcl- 2 and is induced in cells with high c-myc expression. These observations suggest that protooncogenes such as bcl-2 and c-myc have a major role in maintaining anergic cells in vivo. We plan to study the expression of bcl-2 and c-myc in anergic CD4 T cells and their role in maintaining anergic CD4 T cells in vivo. We believe a model system like BM5 retrovirus induced CD4 anergy will enable us to design experiments to follow the course of CD4 T cells as they progressively expand in vivo, yet fail to function and become anergic. This system is well suited to study the biochemical events involved in signal transduction, costimulation and finally apoptosis of anergic CD4 T cells.

BM5，一种逆转录病毒混合物，可诱发致命的免疫缺陷综合症当注射到 C57BL/6 小鼠体内时。这个最有趣的特点是疾病是 CD4 T 细胞诱导疾病的绝对必要条件和进展。有趣的是，随着疾病的发生，CD4 T 细胞变得对多克隆和抗原特异性刺激完全没有反应。此外，BM5逆转录病毒混合物似乎编码或刺激内源性超抗原，删除 Vbeta5.2 阳性 CD4 T 细胞受感染动物的脾脏和淋巴结。该模型提出了一种理想的研究逆转录病毒导致无反应性 CD4 T 细胞的体内系统感染，因为代表各种 Vbeta 的整个 CD4 T 细胞群 TCR 是无能的，并且不限于 CD4 T 细胞的少数亚群。我们将利用这样一个系统来研究无能过程： CD4 T 细胞逐渐丧失增殖或合成能力细胞因子对各种刺激作出反应。最初的方法是查明 TCR 后级联反应中的缺陷步骤刺激。我们将测试酪氨酸发生改变的可能性底物磷酸化，因为它是信号的第一步转导和酪氨酸激酶（例如 p56 1ck、p59）的参与 fyn 和磷酸酶如 CD45 处于无反应状态。信号中的其他步骤转导，即磷酸肌醇水解和随后的 CA++ 将评估 PKC 的释放和激活。接下来我们将监测无能和正常 CD4 T 上各种共刺激分子的表达细胞。为了评估共刺激分子在诱导中的作用淋巴因子基因表达，我们将与无反应 CD4 T 细胞共培养抗CD28或提供B7高表达的APC并研究对 IL-2 和 IL-4 基因转录的影响。在大多数超抗原诱导的无能系统，无能细胞在受到刺激时会发生凋亡通过TCR。 bcl-表达升高的细胞中的细胞凋亡被阻断 2 并在 c-myc 高表达的细胞中被诱导。这些观察表明原癌基因如 bcl-2 和 c-myc 在维持体内无能细胞。我们计划研究bcl-2的表达无能 CD4 T 细胞中的 c-myc 和 c-myc 及其在维持无能 CD4 中的作用体内T细胞。我们相信像 BM5 逆转录病毒诱导的 CD4 无反应性这样的模型系统将使我们能够设计实验来追踪 CD4 T 细胞的过程，因为它们在体内逐渐扩张，但无法发挥作用并变得无反应。这系统非常适合研究信号所涉及的生化事件无反应性 CD4 T 细胞的转导、共刺激和最终凋亡。