小鼠品系和小鼠年龄对实验数据的影响知多少？

‌实验小鼠是进行科学研究常用的实验动物，小鼠不仅和人的基因具有相似度，而且具有体型小、易饲养、生长繁殖快、操作管理方便的优点。随着小鼠在科学研究中的广泛应用，科研人员培育出了许多小鼠品种及品系。在进行研究计划时，选择合适品系的小鼠建立动物疾病模型，是实验设计的关键基础一步。

BALB/c小鼠‌：

‌遗传背景‌：1913年美国国立肿瘤研究所培育，经过多代近交繁殖。

‌特征‌/用途‌：‌

1.性格温顺，易于繁殖，雌雄体重差异小；

2.乳腺肿瘤发病率低(3％)，当用乳腺肿瘤病毒(MTV)诱导时发病率将增高。对矿物油诱导浆细胞瘤敏感，广泛应用于杂交瘤和单克隆抗体的生产；

3.易患慢性肺炎；

4.有自发高血压症，老年鼠心脏病变，雌雄鼠均有动脉硬化，几乎全部20月龄的雄鼠脾脏均有淀粉样变；

5.对放射线敏感，应用于核医学。

‌C57BL/6小鼠‌：

‌遗传背景‌：1921年C.C.Little用Abby Lathrop小鼠培育而成。

‌特征‌/用途‌：

1.已经完成基因组测序的小鼠品系；

2.品系稳定、容易繁殖；

3.试验结果精度高，可比性好，应激反应均一；

4.构建基因修饰动物模型，可保证遗传背景的高度稳定性和实验数据一致性。

有了这些基础知识背景，我们在构建模型时，设计实验时，参考文献时，评价数据时，就能更准确。尤其我们使用荷兰Liposoma巨噬细胞清除剂Clodronate Liposomes氯膦酸盐脂质体清除巨噬细胞时，我们除了关注这些因素，还需要考虑小鼠的周龄。巨噬细胞的高度异质性和可塑性，也觉得巨噬细胞的多功能性和多面性，动态性和适应性。比如巨噬细胞可以质控造血干细胞（见Science文献），巨噬细胞可以和神经元一样调控运动（见Natuer文献）。在这些顶刊的重大研究发现中，研究人员都使用荷兰Liposoma的巨噬细胞清除剂（CP-005-005）货号。此外，巨噬细胞等免疫细胞，在不同品系，不同周龄，不同性别，也是差异很大。见如下这篇文献的基础研究。

小鼠选择

品系：C57BL/6和BALB/c

性别：雄性鼠

周/月龄：1、3、5、10和18月龄

处死方式：通过CO2窒息处死

样品：外周血和脾脏

流式细胞术分析

1、样本制备:

外周血单个核细胞(PBMC):血液PBS稀释后,使用ACK裂解液去除红细胞•脾细胞:机械分离后同样使用ACK裂解液处理

2、抗体标记: 使用荧光标记的单克隆抗体组合:

FITC标记: CD4、CD19、MHC II、CD11b

PE标记: CD3、CD8、CD11c、CD44

PerCP标记: CD3、CD19

研究结果

参考文献：

Pinchuk LM, Filipov NM. Differential effects of age on circulating and splenic leukocyte populations in C57BL/6 and BALB/c male mice. Immun Ageing. 2008 Feb 11;5:1. doi: 10.1186/1742-4933-5-1. PMID: 18267021; PMCID: PMC2268915.

Results

Using a multipoint age comparison approach, cells from the two major immune system compartments, peripheral blood and spleen, and flow cytometry analysis, we found several principal differences in T cell and professional antigen presenting cell (APC) populations originating from a prototypical T helper (Th) 1 mouse strain, C57BL/6, and a prototypical Th2 strain, BALB/c. For example, regardless of age, there were strain differences in both peripheral blood mononuclear cells (PBMC) and spleens in the proportion of CD4+ (higher in the BALB/c strain), CD8+ T cells and CD11b+/CD11c+ APC (greater in C57BL/6 mice). Other differences were present only in PBMC (MHC class II + and CD19+ were greater in C57BL/6 mice) or differences were evident in the spleens but not in circulation (CD3+ T cells were greater in C57BL/6 mice). There were populations of cells that increased with age in PBMC and spleens of both strains (MHC class II+), decreased in the periphery and spleens of both strains (CD11b+) or did not change in the PBMC and spleens of both strains (CD8+). We also found strain and age differences in the distribution of naïve and memory/activated splenic T cells, e.g., BALB/c mice had more memory/activated and less naive CD8+ and CD4+ T cells and the C57BL/6 mice.

Conclusion

Our data provide important information on the principal differences, within the context of age, in T cell and professional APC populations between the prototypical Th1 mouse strain C57BL/6 and the prototypical Th2 strain BALB/c. Although the age-related changes that occur may be rather subtle, they may be very relevant in conditions of disease and stress. Importantly, our data indicate that age and strain should be considered in concert in the selection of appropriate mouse models for immunological research.