奶牛围产期外周血T淋巴细胞亚群动态及细胞因子IL-2、IL-4基因转录水平分析

Analysis on the Dynamic Changes of Lymphocyte Subsets and Genetic Transcription of Cytokine IL-2,IL-4 in Peripheral Blood of Dairy Cows during Perpartum

通过检测奶牛CD3+、CD4+和CD8+淋巴细胞亚群的动态及细胞因子IL-2、IL-4在分娩前后21d内的基因转录水平的变化,以探讨此阶段奶牛免疫机能受损的机理。应用流式细胞术检测CD3+、CD4+、CD8+淋巴细胞亚群的动态变化及实时荧光定量检测细胞因子IL-2、IL-4mRNA的表达量。结果表明:血液中CD3+淋巴细胞的比例在产前21d内占(50.8±4.61)%,产后14d内降低到(39.21±4.98)%,两者差异极显著(P<0.01);CD4+淋巴细胞在产前21d内保持较高水平,达(21.38±0.65)%,产后21d内维持在(6.89±0.32)%的较低水平,且与产前差异显著(P<0.05);CD8+淋巴细胞的比例在产犊前逐渐升高,到产犊时达到最高水平(16.90±2.02)%,差异显著(P<0.05);CD4+/CD8+淋巴细胞的比率在产前>1,产后<1。IL-2mRNA的表达量在产后0～14d内下调,之后上升。IL-4mRNA的表达量分娩时期达到最高,随后下降,至第7天降到最低。奶牛在围产期阶段尤其是分娩前后14d内机体处于免疫抑制状态,可能是由于自身的CD3+、CD4+和CD8+T淋巴细胞的亚群的数量和比例发生改变及细胞因子IL-2、IL-4mRNA表达量下调引起的。

To reveal the mechanism of impaired immune function in perpartum period,the dynamic changes of CD3＋,CD4＋ and CD8＋ in lymphocyte subsets as well as gene transcription level of cytokine IL-2 and IL-4 in peripheral blood of dairy cows during 21 days before calving to 21 days after it were investigated in the present study.The dynamic changes of Lymphocyte cells CD3＋,CD4＋,CD8＋ and the mRNA expression of cytokine IL-2,IL-4 in peripheral blood were determined by flow cytometry and RT-PCR respectively.The results showed that significant difference was found in the proportion of CD3＋ in peripheral blood 21 days before calving（50.8±4.61）% and 14 days after caving（39.21±4.98）%,and also was found in the proportion of CD4＋ in blood before（21.38±0.65）% and after（6.89±0.32）% calving.The proportion of CD8＋ increased to the highest level（16.9±2.02）% during calving（P0.05）.The ratio of CD4＋/CD8＋ was 1 before calving,and 1 after calving.The mRNA expression of IL-2 was the lowest（P0.05） during 0-14 days after calving,then gradually increased.The mRNA expression of IL-4 increased to the peak during calving,and declined to the lowest level on the 7th day（P0.01）.It was suggested that the immune function of dairy cows was impaired within 21 days before and after calving,especially during the 0-14 days after caving.This might be caused by the quantity and ratio changes of lymphocyte subsets（CD3＋,CD4＋and CD8＋） and the down-regulation of the cytokine IL-2,IL-4 during this critical period.