Up-regulation of human immune system function by Donkey’s Milk

Donkey’s milk represents a good alternative to human milk because of its chemical characteristics similar to those of human’s. In present study, the pro- and anti-inflammatory effects of donkey’s milk were evaluated on peripheral blood mononuclear cells (PBMCs). PBMCs were isolated from 12 young and 12 aged normal subjects. PBMCs were cultured with or without the optimal and non-cytotoxic dose of pasteurized donkey’s milk, and polymyxin B was used to inhibit the possible endotoxin contamination. Following 18 hours incubation, culture supernatants were harvested to measure the secreted Tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), Interleukin-8 (IL-8) and Interleukin-10 (IL-10) by ELISA. Donkey’s milk significantly increased TNF-α (p= 0.01), IL-8 (p< 0.0001), IL-6 (p< 0.0001) and IL-10 (p= 0.01) levels in PBMCs. In addition, the levels of IL-6 (p= 0.002), IL-8 (p= 0.002) and TNF-α (p= 0.002) from aged subjects were significantly higher compared with young subjects. In contrast with these data, the level of IL-10 was markedly reduced from aged subjects (p= 0.02). Considering the immune-potentiation effects of donkey’s milk, it is suggested investigating milk as a beneficial dietary component for up-regulating the immune response in aged people.

驴乳因化学组成与母乳高度相似，是母乳的优质替代选择。本研究以人外周血单个核细胞（peripheral blood mononuclear cells, PBMCs）为模型，评估了驴乳的促炎与抗炎效应。实验共招募12名青年健康受试者与12名老年健康受试者，分离其外周血单个核细胞。将分离得到的PBMCs分别置于添加/不添加最优非细胞毒性剂量巴氏消毒驴乳的培养基中培养，同时加入多粘菌素B以抑制可能存在的内毒素污染。孵育18小时后收集细胞培养上清液，通过酶联免疫吸附实验（Enzyme-Linked Immunosorbent Assay, ELISA）检测其中分泌的肿瘤坏死因子-α（Tumor necrosis factor-α, TNF-α）、白细胞介素-6（Interleukin-6, IL-6）、白细胞介素-8（Interleukin-8, IL-8）与白细胞介素-10（Interleukin-10, IL-10）水平。结果显示，驴乳可显著上调PBMCs中TNF-α（p=0.01）、IL-8（p<0.0001）、IL-6（p<0.0001）与IL-10（p=0.01）的分泌水平。此外，老年受试者来源的PBMCs分泌的IL-6（p=0.002）、IL-8（p=0.002）与TNF-α（p=0.002）水平显著高于青年受试者；与之相反，老年受试者来源的PBMCs分泌的IL-10水平显著降低（p=0.02）。鉴于驴乳具备免疫增强活性，本研究提示可进一步探讨将驴乳作为有益膳食成分，用于上调老年人群的免疫应答水平。