CD8α在雄性牦牛主要免疫器官的分布

Expression of CD8α in the Major Immune Organs of Male Yaks

CD8α是细胞毒性T淋巴细胞重要的表面标志,广泛参与对MHCⅠ分子递呈抗原的识别和信号传递,对细胞免疫应答和防御机制至关重要。本研究采用RT-PCR方法克隆牦牛(Bos grunniens)CD8α编码区,通过实时荧光定量PCR、Western blot及免疫组织化学SP法,检测成年雄性牦牛的主要免疫器官(胸腺、脾、肠系膜淋巴结及血结)内CD8αmRNA及蛋白的表达。RT-PCR反应扩增得到牦牛CD8αmRNA序列编码区长为729bp,编码243个氨基酸,与黄牛有较高的同源性。实时荧光定量PCR和Western blot检测结果显示,CD8αmRNA及蛋白在各免疫器官中均有表达,且在胸腺表达量最高,在脾与血结表达量相似,二者表达量均高于肠系膜淋巴结(P<0.01)。免疫组织化学结果显示,CD8α阳性T细胞在胸腺皮质、髓质均有分布;在脾主要分布在动脉周围淋巴鞘和红髓髓索;肠系膜淋巴结及血结内,CD8α阳性细胞主要分布在淋巴小结周边及髓索。结果提示,牦牛胸腺的CD8α阳性T淋巴细胞输出量可能影响次级淋巴器官内T细胞含量;血结可能与淋巴结及脾一样,在细胞免疫发挥同等重要的作用。这些数据将为适时免疫、致病机理和疾病防治等研究提供新的资料。

CD8αis an important surface marker of cytotoxic T lymphocyte.This molecule is critical for cell-mediated immune response and defense mechanisms,widely involved in recognition of specific antigens in association with MHCⅠ molecules and transmembrane signal transduction.In this study,the yak(Bos grunniens)CD8αwas cloned using RT-PCR,and the expression of CD8αmRNA and protein in the major immune organs(thymus,spleen,mesenteric lymph nodes and haemal nodes)of adult male yaks were detected by means of quantitative real-time fluorescence quantitative PCR,Western blots and immunohistochemical SP methods.The RT-PCR results showed the coding sequence of yak CD8αcontained 729 bp,encoded for 243 amino acids.The cDNA sequences of yak CD8αrevealed significant homology with Bos taurus.The quantitative real-time fluorescence quantitative PCR and Western blot results showed that CD8α mRNA and protein were widely expressed in immune organs.The expression levels in the thymus was the highest than other immune organs(P<0.01);additionally the levels of haemal nodes was similar to that of spleen,and both of them were higher than those for mesenteric lymph nodes(P<0.01).Moreover,the immunohistochemical results showed the CD8α+cells were distributed in the cortex and medulla of yak thymus.In the spleen,many CD8α+cells were located in the periarteriolar lymph-oid sheaths and red pulp.Moreover CD8α+cells in mesenteric lymph nodes and haemal nodes were mainly presented in the mantle zone and medulla.The results indicated the thymic production might influence the CD8α+T lymphocytes extent of secondary immune organs.Then haemal nodes might have similar functions in cellular immunity as the mesenteric lymph nodes and spleen.These datas would provide new insights into timely immunization,the pathogenesis and disease prevention.