CD4 T CELL ANERGY IN MURINE AIDS

BM5，逆转录病毒的混合物诱导致命的免疫缺陷综合征 注射到C57BL/6小鼠体内。其中最有趣的特点是 疾病是CD4T细胞诱导疾病的绝对要求 和进步。有趣的是，随着疾病的开始，CD4T细胞 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了一种 内源性超抗原清除体内Vbeta5.2阳性的CD4T细胞 感染动物的脾和淋巴结。这一模式体现了 体内系统研究由逆转录病毒引起的无能的CD4T细胞 感染是因为代表不同Vbeta的整个CD4T细胞群 TCRs是无能的，并不局限于少数CD4T细胞亚群。 我们将利用这样的系统来研究无能的过程 CD4T细胞逐渐丧失其增殖或合成能力 细胞因子对各种刺激的反应。最初的方法是 在TCR之后的一系列反应中找出有缺陷的步骤 刺激。我们将测试是否存在一种改变的酪氨酸 底物的磷酸化，因为它是信号的第一步 P56-1ck、p59等酪氨酸激酶的转导与参与 Fyn和CD45等磷酸酶在无能中起作用。信号中的其他步骤 转导，即磷脂酰肌醇的水解和随后的Ca++ 将评估PKC的释放和激活。接下来，我们将关注 多种共刺激分子在无能和正常CD4T细胞上的表达 细胞。为了评估共刺激分子在诱导 淋巴因子基因的表达，我们将与无能的CD4T细胞共培养 抗CD28或提供高表达B7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下 无能系统，无能细胞在受到刺激时会发生凋亡 通过TCR。Bcl-1高表达细胞的细胞凋亡受阻 2，并在c-myc高表达的细胞中诱导。这些观察结果 提示原癌基因如bcl2和c-myc在 在体内维持无能细胞。我们计划研究bcl2的表达。 和c-myc在无能CD_4 T细胞中的表达及其在维持无能CD_4中的作用 体内的T细胞。 我们相信，像BM5逆转录病毒诱导的CD4无能这样的模型系统将 使我们能够设计实验来跟踪CD4T细胞的过程 在体内逐渐扩张，但仍无法发挥作用，变得无能。这 该系统非常适合于研究信号中涉及的生化事件 无能的CD4T细胞的转导、共刺激和最终的凋亡。

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.