INTERLEUKIN 2 RECEPTORS IN AGING

免疫系统是一种特别吸引人的器官系统 用来研究细胞增殖能力减弱的原因 老年人由于细胞的可获得性和临床 免疫功能缺陷的意义。老年人有一种 白介素2(IL-2)的产生减少，这是一种基本的生长 T细胞增殖因子。在小鼠体内，外源性IL-2是 显示在很大程度上纠正了许多体外功能缺陷。使用 然而，在体外培养的人类细胞中，这并不有效； 其他因素也必须发挥重要作用。诱导细胞 生长，IL-2必须与特定的高亲和力受体相互作用 (IL-2R)表达于活化的T细胞表面。是这样的 活化的T细胞也表达低亲和力的IL-2受体和 释放一种可溶性的IL-2R，两者的功能都不是 为人所知。初步实验表明，老年人 释放相对过量的可溶性IL-2R，以达到 有丝分裂原诱导的增殖。膜的表达- 结合的IL-2R在老年人中还没有得到很好的表征，但 在数量有限的捐赠者中，老年人似乎表达了一种 每个激活细胞的受体密度更高。 这项提案旨在研究膜结合的 和健康老年供者的可溶性IL-2R。膜结合型IL-2 2R的研究将利用125I标记的IL-2来确定 高表达和低表达的数量、亲和力和动力学 亲和力受体种群。将对可溶性IL-2R进行研究 通过量化其从刺激的T细胞中释放出来。它们的起源 在老年人和年轻人中也将检测可溶性IL-2R 本征放射性标记实验及蛋白水解剂的应用 和溶酶体酶抑制剂。可溶性IL-2R的功能 将利用重组DNA的制剂进行分析- 产生的IL-2R已被修改为缺乏 分子的跨膜部分以及制剂 从培养上清液中粗提纯的可溶性IL-2R。在……里面 将测试体外胸腺激素对IL-2R的影响 在老年人细胞中的表达。 这些项目的实验方法包括：a)细胞 使用标准技术进行分离，b)细胞培养 淋巴细胞激活剂的种类，c)膜结合力测定 放射性标记白介素2与白介素2受体结合的研究 IL-2R酶联免疫吸附试验，e)聚丙烯酰胺 凝胶电泳法和f)凝胶渗透层析法。

The immune system is an especially attractive organ system in which to study the diminished proliferative capacity of cells in the elderly due to accessibility of cells and the clinical significance of immune function defects. The aged have a diminished production of interleukin 2 (IL-2), an essential growth factor for T cell proliferation. In the mouse, exogenous IL-2 was shown to largely correct many in vitro functional deficits. With human cells in vitro, however, this has not been effective; thus; other factors must also play important roles. To induce cell growth, IL-2 must interact with specific high affinity receptors (IL-2R) displayed on the surface of activated T cells. Such activated T cells also express low affinity IL-2 receptors and release a soluble from of IL-2R, neither of whose functions are known. Preliminary experiments demonstrate that the aged release a relative excess of soluble IL-2R for the level of mitogen-induced proliferation. The expression of membrane- bound IL-2R has not been well-characterized in the elderly, but in a limited number of donors, the aged appear to express a higher density of receptors per activated cell. This proposal is designed to investigate both membrane-bound and soluble IL-2R in healthy aging donors. membrane-bound IL- 2R will be studied utilizing 125I-labelled IL-2 to determine the number, affinity, and kinetics of expression of both high and low affinity receptor populations. Soluble IL-2R will be investigated by quantitating its release from stimulated T-cells. The origins of soluble IL-2R will also be examined in the old and young by intrinsic radiolabelling experiments and the use of proteolytic and lysosomal enzyme inhibitors. The functions of soluble IL-2R will be analyzed utilizing preparations of a recombinant DNA- produced IL-2R which has been modified to lack the transmembrane portion of the molecule, as well as preparations of soluble IL-2R crudely purified from culture supernatants. In vitro thymic hormones will be tested for effects on IL-2R expression in cells from the aged. Experimental methods for these projects include: a) cell separations using standard techniques, b) cell culture with a variety of lymphocyte activators, c) assay of membrane-bound IL-2R binding by radiolabelled IL-2, d) determination of soluble IL-2R by enzyme-linked immunosorbent assay, e) polyacrylamide gel electrophoresis, and f) gel permeation chromatography.