Dunn-Walters Deborah K, Stewart Alexander T, Sinclair Emma L, Serangeli Ilaria
School of Biosciences and Medicine, University of Surrey, Guildford, United Kingdom,
School of Biosciences and Medicine, University of Surrey, Guildford, United Kingdom.
Interdiscip Top Gerontol Geriatr. 2020;43:56-72. doi: 10.1159/000504479. Epub 2020 Apr 9.
Older people have reduced immune responses to infection and vaccination. B cell activation is key for the efficacy of the vaccine response, but there are several age-related changes in B cells which may contribute to the loss of vaccine efficacy. Different subpopulations of B cells have different functions and phenotypes. These populations can change as we age; older people have been shown to have fewer "IgM memory" cells, regulatory B cells and plasma cells and more IgD-CD27- "double-negative" and "age-related B cells." While the overall quantity of antibody in the blood does not change, the quality of the B cell response changes; producing less specific antibodies upon challenge and more autoreactive antibodies. This could be due to changes in selection pressures, as has been demonstrated by repertoire sequencing of different subsets of B cells at different ages. Other changes in antibody repertoire are seen, including greater levels of IgG2 in older people and altered IgG1 IGHV gene usage. Since B cells rely on their environment for efficient responses, some of these changes may be due to age-related changes in accessory cells/signals. Other changes appear to be intrinsic to older/aged B cells themselves, such as their tendency to produce greater levels of inflammatory cytokines.
老年人对感染和疫苗接种的免疫反应会降低。B细胞活化是疫苗反应有效性的关键，但B细胞存在一些与年龄相关的变化，这可能导致疫苗效力丧失。不同亚群的B细胞具有不同的功能和表型。随着年龄增长，这些细胞群会发生变化；研究表明，老年人的“IgM记忆”细胞、调节性B细胞和浆细胞较少，而IgD-CD27-“双阴性”和“年龄相关B细胞”较多。虽然血液中抗体总量不变，但B细胞反应的质量发生了变化；受到刺激时产生的特异性抗体减少，自身反应性抗体增多。这可能是由于选择压力的变化，不同年龄B细胞不同亚群的重排测序已证明了这一点。还观察到抗体库的其他变化，包括老年人中IgG2水平较高以及IgG1 IGHV基因使用情况改变。由于B细胞的有效反应依赖于其所处环境，其中一些变化可能是由于辅助细胞/信号的年龄相关变化所致。其他变化似乎是老年B细胞自身固有的，例如它们产生更高水平炎性细胞因子的倾向。
