双歧杆菌及其完整肽聚糖对脐血来源树突状细胞分泌IL-12的影响

目的探讨两歧双歧杆菌和不同剂量双歧杆菌的完整肽聚糖（WPG）对脐血来源树突状细胞（DC）分泌IL-12的影响。方法以双歧杆菌全菌（量）和不同剂量双歧杆菌WPG（1-8μg/ml）与脐血来源树突状细胞共培养,用ELISA的方法测定培养上清中IL-12的量。结果双歧杆菌和其WPG（1-6μg/ml）与树突状细胞共培养后,树突状细胞分泌的IL-12的量显著高于阴性对照组（P〈0.01）,当WPG量为1-5μg/ml时树突状细胞分泌的IL-12的量呈剂量依赖性,其中WPG量为5μg/ml时作用最为显著,WPG量为6μg/ml时分泌IL-12量减少,WPG量为8μg/ml时,分泌的IL-12量与阴性对照组差异无显著性（P〉0.05）。结论两歧双歧杆菌及其WPG能够刺激脐血来源的树突状细胞IL-12分泌;双歧杆菌WPG的免疫刺激作用呈一定的量效关系

The influence of Bifidobacterium bifidum and whole peptidoglycan of Bifidobacterium on interleukin 12 produced by dendritic cells derived from cord blood in vitro

Objective To explore in vitro whether the Bifidobacterium bifidum and different dose whole peptidoglycans of Bifidobacterium（WPG） effect on the generation of interleukin 12 secreted by the DC deriving from cord bloods. Methods In vitro,immature DCs were induced by monocyte cultured in granulocytes macrophage-colony stimulating factor （GM-CSF） and interleukin-4 on the 7th day. Immature DCs were exposed to heat-killed bifidobacteria（ 100 μg/ml） and various dosages of WPG（ 1 - 8 μg/ml） ;while the negative control group was exposed to the medium only;LPS at 1 μg/ml was added to some cultures as positive control. The supernatant was collected on the 9th day,and the level of interleukin 12 was detected by Enzyme-labeled immunosorbent assay （ELISA）. Results The level of interleukin 12 secreted from dendritic cells co-cultured with Bifidobacterium bifidum and WPG （ 1-6 μg/ml） was significantly higher compared with the negative control group（ P 〈 0.01 ） ;the secretion of interleukin-12 by DC was dose-dependent while the concentration of WPG from 1μg/ml to 5 μg/ml. The level of interleukin 12 reaches the peak at WPG 5μg/ml which was higher than WPG with the concentration of 6 μg/ml;there was no difference between WPG group at the concentration of 8 μg/ml and negative control group （P〉0.05）. Conclusion The level of IL-12 secreted by DC derived from cord blood has been remarkably elevated after the stimulation of the Bifidobacterium bifidum and WPG. Meanwhile the immunostimulation of WPG have dose-effect relationship in some degree.