Effect of Age on Antibody Diversity

为了确定老年B细胞是否具有与年轻细胞相同的转换同种型的能力，我们从C57 BL/6小鼠中纯化了脾滤泡、边缘区和年龄相关的B细胞亚群。在培养中用白细胞介素4和脂多糖或抗CD 40刺激细胞，并通过表面免疫球蛋白的流式细胞术测量向IgG 1的转换。结果显示，老年小鼠的滤泡和边缘区B细胞中的转换是稳健的，并且与年轻小鼠相当。然而，与年龄相关的B细胞相对于其他亚群的转换较差。通过mRNA的qPCR定量激活诱导的脱氨酶（启动转换）的表达，并且其在年轻和老年滤泡B细胞之间相等。因此，在这种离体系统中，来自年轻小鼠和老年小鼠的滤泡和边缘区细胞表现相似，表明在老年B细胞中进行转换的分子机制是完整的。 适应性免疫反应与心血管疾病有关，这表明潜在的免疫干预策略可以降低疾病严重程度并延长寿命。为了实现这一目标，我们一直致力于了解B细胞在动脉粥样硬化中的作用。我们正在使用一种新的小鼠模型测试抗体同种型的作用，我们正在表征小鼠主动脉B细胞产生的抗体。我们还在确定它们结合的抗原以及抗体如何促进疾病。

To determine whether old B cells have the same capacity to switch isotypes as young cells, we purified splenic follicular, marginal zone, and age-associated B cell subsets from C57BL/6 mice. Cells were stimulated in culture with interleukin 4 and either lipopolysaccharide or anti-CD40, and switching to IgG1 was measured by flow cytometry of surface immunoglobulin. The results show that switching was robust in follicular and marginal zone B cells from old mice and was comparable to their young counterparts. However, age-associated B cells from old mice switched poorly relative to the other subsets. Expression of activation-induced deaminase, which initiates switching, was quantified by qPCR of mRNA, and it was equal between young and old follicular B cells. Thus, in this ex vivo system, the follicular and marginal zone cells from young and old mice behaved similarly, showing that the molecular machinery to perform switching is intact in old B cells. The adaptive immune response has been linked to cardiovascular disease, suggesting that potential immune intervention strategies could reduce disease severity and prolong life. To achieve this goal, we have focused on understanding the role of B cells in atherosclerosis. We are testing the role of antibody isotype using a novel mouse model, and we are characterizing the antibodies produced by mouse aortic B cells. We are also determining what antigens they bind and how antibodies can promote disease.