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类型的能力，我们从C57BL/6小鼠的脾滤泡、边缘带和年龄相关的B细胞亚群中纯化了它们。用白介素4、脂多糖或抗CD40刺激细胞，用流式细胞仪检测细胞表面免疫球蛋白向IgG1的转化。结果表明，老年小鼠滤泡和边缘区B细胞的转换很强，与年轻小鼠相当。然而，来自老年小鼠的与年龄相关的B细胞相对于其他亚群来说切换得很差。启动转换的激活诱导脱氨酶的表达通过mRNA的qPCR定量，在年轻和老年滤泡B细胞中的表达相同。因此，在这个体外系统中，年轻和老年小鼠的滤泡和边缘带细胞的行为相似，表明执行切换的分子机制在老年B细胞中是完整的。 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的严重性，延长生命。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来测试抗体同型的作用，我们正在鉴定小鼠主动脉B细胞产生的抗体。我们还在确定它们结合的是什么抗原，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.