INTERLEUKIN 2 RECEPTORS IN AGING

免疫系统是一个特别有吸引力的器官系统， 这是为了研究细胞增殖能力的下降， 老年人由于细胞的可及性和临床 免疫功能缺陷的意义。 老年人有一个 白细胞介素2（IL-2）的产生减少， T细胞增殖因子。 在小鼠中，外源性IL-2是 在很大程度上纠正了许多体外功能缺陷。 与 然而，在体外的人细胞中，这并不有效;因此; 其他因素也必须发挥重要作用。 诱导细胞 生长，IL-2必须与特异性高亲和力受体相互作用 （IL-2 R）在活化的T细胞表面上展示。 等 活化的T细胞也表达低亲和力IL-2受体， 释放一种可溶性的IL-2 R，其功能都不是 知道的 初步实验表明，老年人 释放相对过量的可溶性IL-2 R， 丝裂原诱导的增殖。 膜的表达- 结合的IL-2 R在老年人中尚未得到很好的表征，但 在有限数量的捐赠者中，老年人似乎表达了一种 每个激活细胞的受体密度更高。 该建议旨在研究膜结合的 和可溶性IL-2 R。 膜结合IL- 将使用125 I标记的IL-2对2 R进行研究，以确定 表达的数量、亲和力和动力学 亲和受体群体。 将研究可溶性IL-2 R 通过量化它从刺激的T细胞中的释放。 起源 可溶性IL-2 R也将在老年人和年轻人中进行检查， 内在放射性标记实验和使用蛋白水解 和溶酶体酶抑制剂。 可溶性IL-2 R的功能 将利用重组DNA的制备物进行分析， 产生的IL-2 R经过修饰， 分子的跨膜部分，以及制备物 从培养上清液中粗纯化的可溶性IL-2 R。 在 将测试体外胸腺激素对IL-2 R的影响 在老年人的细胞中表达。 这些项目的实验方法包括： 使用标准技术分离，B）用 各种淋巴细胞活化剂，c）膜结合 通过放射性标记的IL-2测定IL-2 R结合， 通过酶联免疫吸附测定法测定IL-2 R，e）聚丙烯酰胺 凝胶电泳和f）凝胶渗透色谱法。

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.