CD4 T CELL ANERGY IN MURINE AIDS

逆转录病毒混合物BM 5引起致命性免疫缺陷综合征 当注射到C57 BL/6小鼠中时。最有趣的是 疾病是疾病诱导对CD 4 T细胞的绝对要求 和进步。有趣的是，随着疾病的发生，CD 4 T细胞 对多克隆和抗原特异性刺激完全无反应。 此外，BM 5逆转录病毒混合物似乎编码或刺激了一种新的逆转录病毒。 内源性超抗原，其删除了V5.2阳性CD 4 T细胞， 脾脏和淋巴结。该模型提出了一种理想的， 研究逆转录病毒致无能的CD 4 T细胞的体内系统 感染，因为整个CD 4 T细胞群代表各种V β TCR是无反应性的，并且不限于CD 4 T细胞的少数亚群。 我们将利用这样一个系统to.study的无功过程， CD 4 T细胞逐渐失去增殖或合成的能力 细胞因子对各种刺激的反应。最初的做法是 在TCR之后的级联反应中， 刺激.我们将测试是否有一个改变的酪氨酸 底物的磷酸化，因为它是信号转导的第一步。 转导和酪氨酸激酶如p56 1ck、p59 fyn和磷酸酶如CD 45在无能中的作用。信号中的其他步骤 转导，即磷酸肌醇水解和随后的CA++ 将评价PKC的释放和活化。接下来，我们将监测 各种共刺激分子在无能和正常CD 4 T细胞上的表达 细胞为了评估共刺激分子在诱导细胞凋亡中的作用， 淋巴因子基因表达，我们将无反应性CD 4 T细胞与 抗CD 28或提供具有B7高表达的APC，并研究B7的表达。 对IL-2和IL-4基因转录的影响。在大多数超抗原诱导的 无反应性系统，无反应性细胞在受到刺激时发生凋亡 通过TCR。凋亡在bcl-2表达升高的细胞中被阻断， 2，并在具有高c-myc表达的细胞中诱导。这些观察结果 提示原癌基因如bcl-2和c-myc在 维持体内无反应性细胞。我们计划研究bcl-2的表达 和c-myc在无能性CD 4 T细胞中的表达及其在维持无能性CD 4 T细胞中的作用 体内T细胞。 我们相信，一个模型系统，如BM 5逆转录病毒诱导的CD 4无反应性， 使我们能够设计实验来跟踪CD 4 T细胞的过程，因为它们 在体内逐渐扩增，但不能发挥功能并变得无反应性。这 系统非常适合于研究信号中涉及的生化事件 转导、共刺激和最后的无反应性CD 4 T细胞凋亡。

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.