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，我们纯化了来自C57BL/6小鼠的脾滤泡、边缘区和年龄相关的B细胞亚群。用白细胞介素4和脂多糖或抗cd40刺激细胞，用表面免疫球蛋白流式细胞术检测细胞向IgG1的转换。结果表明，老年小鼠的滤泡和边缘区B细胞的转换是稳健的，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切换较差。激活诱导的脱氨酶，启动开关，通过mRNA的qPCR定量表达，在年轻和老年滤泡B细胞中表达相等。因此，在这个离体系统中，来自年轻和年老小鼠的滤泡和边缘带细胞表现相似，表明在老年B细胞中进行转换的分子机制是完整的。

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.