The study of immune system aging is of relevance, considering its myriad of interactions and role in protecting and maintaining body homeostasis. While mouse models have been extensively used to study immune system aging, little is known on how the main immune populations progress over time and what is the impact of sex. To contribute to filling this gap, male and female BALB/cByJ mice were longitudinally evaluated, from 3 to 18 months old, for the main blood populations, assessed by flow cytometry. Using linear mixed-effect models, we observed that the percentages of neutrophils, monocytes, eosinophils, and total natural killer (NK) cells increase with aging, while those of B cells, T cells (including CD4+ and CD8+ subsets), and Ly6C+ NK cells decrease. Males present higher percentages of neutrophils and classical monocytes Ly6Chigh over time, while females present higher percentages of total T cells, both CD4+ and CD8+, eosinophils, and NK cells. Males and females display similar percentages of B cells, even though with opposite accelerated progressions over time. This study revealed that mouse models recapitulate what is observed in humans during aging: an overall proportional decrease in the adaptive and an increase in the innate immune cells. Additionally, it uncovers an age-related sexual dimorphism in the proportion of immune cells in circulation, further strengthening the need to explore the impact of sex when addressing immune system aging using mouse models.

中文翻译：

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BALB/cByJ 小鼠血液免疫细胞纵向进展的年龄相关性二态性

考虑到免疫系统衰老在保护和维持身体稳态中的无数相互作用和作用，研究免疫系统衰老具有相关性。虽然小鼠模型已被广泛用于研究免疫系统衰老，但人们对主要免疫群体如何随着时间的推移以及性别的影响而知之甚少。为了填补这一空白，对雄性和雌性 BALB/cByJ 小鼠进行纵向评估，从 3 到 18 个月大，通过流式细胞术评估主要血群。使用线性混合效应模型，我们观察到中性粒细胞、单核细胞、嗜酸性粒细胞和总自然杀伤 (NK) 细胞的百分比随着衰老而增加，而 B 细胞、T 细胞（包括 CD4+ 和 CD8+ 亚群）和 Ly6C+ NK 细胞的百分比细胞减少。随着时间的推移，男性中性粒细胞和经典单核细胞 Ly6Chigh 的百分比更高，而女性的总 T 细胞百分比较高，包括 CD4+ 和 CD8+、嗜酸性粒细胞和 NK 细胞。男性和女性的 B 细胞百分比相似，尽管随着时间的推移会出现相反的加速进展。这项研究表明，小鼠模型概括了人类在衰老过程中观察到的情况：适应性总体上成比例的下降和先天免疫细胞的增加。此外，它揭示了循环中免疫细胞比例与年龄相关的性别二态性，进一步加强了在使用小鼠模型解决免疫系统老化问题时探索性别影响的必要性。这项研究表明，小鼠模型概括了人类在衰老过程中观察到的情况：适应性总体上成比例的下降和先天免疫细胞的增加。此外，它揭示了循环中免疫细胞比例与年龄相关的性别二态性，进一步加强了在使用小鼠模型解决免疫系统老化问题时探索性别影响的必要性。这项研究表明，小鼠模型概括了人类在衰老过程中观察到的情况：适应性总体上成比例的下降和先天免疫细胞的增加。此外，它揭示了循环中免疫细胞比例与年龄相关的性别二态性，进一步加强了在使用小鼠模型解决免疫系统老化问题时探索性别影响的必要性。