THE B-CELL REPERTOIRE OF AGED MICE

衰老伴随着B细胞谱系的大量变化 表达能力和反应能力。尽管衰老小鼠的B细胞对 正常情况下对T/H依赖的抗原和总数量和多样性 B细胞的数量保持不变，B细胞对某些 抗原被改变，产生高亲和力记忆B的能力 细胞被破坏了。这是一项延续我们长期以来 这些衰老的细胞和分子基础的研究 免疫反应中B细胞成分的相关变化。 尽管新生成的B细胞的数量并没有明显减少 衰老小鼠的B细胞发育途径被改变，以至于 成熟的前B细胞的数量减少了好几倍。要确定 如果这是由于前B细胞克隆性增殖减少所致 在具体目标1中，我们将评估独特H的复发 不同发育B细胞亚群细胞中的链V区 取自个体股骨的骨髓。我们还将使用Single 细胞聚合酶链式反应，以确定前B细胞成熟是否可能被加速 过早的L连锁反应。以确定克隆数量的减少是否 老年小鼠的消除(耐受)有助于维持 新生成的B细胞数量正常，在特定目标2中，我们将 确定SLG受体介导的排泄是否减少 新生成的表达由V(H)81X-D-J(H)编码的H链的B细胞 重新安排。最后，评估以下项目的潜在贡献 记忆祖细胞对代谢率下降的影响 高亲和力体细胞突变的记忆B细胞，在特定的目标3我们 将克隆地评估从以下来源获得的记忆前体的能力 幼稚和免疫的老龄小鼠产生记忆B细胞并积累 体外体细胞突变。

Aging is accompanied by numerous alterations in B cell repertoire expression and responsiveness. Although B cells of aged mice respond normally to T/H dependent antigens and the overall numbers and diversity of B cells is maintained, the repertoire of B cells responsive to certain antigens is altered and the capacity to generate high affinity memory B cells is compromised. This is a proposal to continue our long-standing investigation of the cellular and molecular basis of these aging associated alterations in the B cell component of the immune response. Although the number of newly generated B cells is not markedly reduced in aged mice the pathway of B cell development is altered such that the population of mature pre B cells is decreased several fold. To determine if this is due to a decrease in clonal expansion during pre B cell development, in Specific Aim 1 we will assess the recurrence of unique H chain V regions in cells within various developmental B cell subsets obtained from the marrow of individual femora. We will also use single cell PCR to determine whether pre B cell maturation may be accelerated by premature L chain expression. To determine if a decrease in clonal elimination (tolerance) in aged mice contributes to the maintenance of normal numbers of newly generated B cells, in Specific Aim 2 we will determine if there is a decrease in slg receptor mediated elimination of newly generated B cells that express H chains encoded by V(H)81X-D-J(H) rearrangements. Finally, to assess the potential contribution of alterations in memory progenitors to the decrease in the generation of high affinity somatically mutated memory B cells, in Specific Aim 3 we will evaluate, clonally, the capacity of memory progenitors obtained from naive and immunized aged mice to generate memory B cells and accumulate somatic mutations in vitro.