MOLECULAR CHANGES IN ANTIBODY AFFINITY IN THE ELDERLY

描述(改编自申请人的摘要)：目标 这项建议是为了研究能力下降的分子基础。 在许多老年人的免疫系统中，产生高 亲和抗体，从而对 疫苗或感染。为了实现这一目标，校长 研究人员将研究这段关系中与年龄相关的变化 免疫球蛋白VH和VL基因结构与功能的关系 产生天然的抗Gal抗体。抗-Gal占1% 在人类中循环的免疫球蛋白，并与 糖类结构Gala1-3GalB1-4GlcNAc-R(称为α-半乳糖基 表位)。高达1%的循环B淋巴细胞可以产生抗- 盖尔。申请人发现，大多数已测序的VH基因在 产生抗Gal的淋巴克隆，聚集在不同的区域内 VH3免疫球蛋白基因家族，这些基因经历了体细胞 突变。抗GAL活性的增龄性变化分析 在许多老年人中表现出这种抗体的亲和力丧失 个人。首席调查员建议研究两种可能的 抗半乳糖胺增龄性损害的可能机制 人类的亲和力：1)VH和VL基因的不同利用 抗半乳糖合成谱系；和2)亲和力成熟受损 由于体细胞中年龄相关的变化而产生的抗半乳糖基因 突变的过程。为此，他将构造组合 年轻人和老年人的噬菌体展示文库和分离株 抗半乳糖展示噬菌体。抗Gal VH抗体的比较分析 和VL基因谱在青年和老年人群中的应用 由此产生的抗体亲和力，将使申请人能够确定 与年龄相关的抗体亲和力下降是否与 用于抗Gal合成的基因谱系。V字的比较 带有相应生殖系基因的基因序列将允许 调查人员试图确定与年龄相关的变化是否反映了 抗半乳糖产生基因的体细胞突变过多或过少。这个 申请人将进一步确定是否有低收入的老年人 亲和血清抗Gal通过筛选保留了部分高亲和力克隆 从这些个体的文库中获得高亲和力的抗Gal噬菌体。 最后，通过将抗Gal亲和力与免疫反应相关联， 流感病毒疫苗，首席调查员将确定 抗-Gal抗体能否预测免疫系统的活性 老年人个体产生高亲和力抗体。因此，通过 利用反Gal系统，申请人的目的是了解 已有文献记载的增龄性脑损伤的分子基础 人类的体液免疫反应。

DESCRIPTION (Adapted from the Applicant's Abstract): The objective of this proposal is to study the molecular basis for the decreased ability of the immune system in many elderly individuals, to produce high affinity antibodies and thus mount an effective immune response to vaccines or infections. To pursue this objective, the principal investigator will study the age-associated changes in the relationship between structure and function of immunoglobulin VH and VL genes which produce the natural anti-Gal antibody. Anti-Gal constitutes 1% of circulating IgG in humans and interacts specifically with the carbohydrate structure Gala1-3GalB1-4GlcNAc-R (termed alpha-galactosyl epitope). As many as 1% of circulating B lymphocytes can produce anti- Gal. The applicant has found that most of the sequenced VH genes in anti-Gal producing lymphoid clones, cluster within a distinct region of the VH3 immunoglobulin gene family, and that these genes undergo somatic mutations. Analysis of age-associated changes in activity of anti-Gal have demonstrated loss of affinity of this antibody in many elderly individuals. The principal investigator proposes to study two possible mechanisms which may cause the age-associated impairment in anti-Gal affinity in humans: 1) different utilization of VH and VL genes repertoire for anti-Gal synthesis; and 2) impaired affinity maturation in anti-Gal genes because of age-associated changes in the somatic mutations process. For this purpose he will construct combinatorial phage display libraries in young and in elderly individuals and isolate the anti-Gal displaying phage. Comparative analysis of the anti-Gal VH and VL gene repertoire in the young and elderly, and determination of the resulting antibody affinities, will enable the applicant to establish whether the age-associated decrease in antibody affinity correlates with the gene repertoire used for anti-Gal synthesis. Comparison of the V gene sequences with the corresponding germline genes will allow the investigators to establish whether the age-associated changes reflect the excess or paucity of somatic mutations in anti-Gal producing genes. The applicant will further determine whether elderly individuals with low affinity serum anti-Gal retain some high affinity clones, by selecting high affinity anti-Gal phage from the libraries of these individuals. Lastly, by correlating anti-Gal affinity with the immune response to an influenza virus vaccine, the principal investigator will determine whether anti-Gal can predict the competence of the immune system in elderly individuals to produce high affinity antibodies. Thus, by exploiting the anti-Gal system, the applicant aims to understand the molecular basis of the well-documented age-associated impairment of humoral immune responses in humans.