Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7040, USA.
BMC Vet Res. 2013 Apr 19;9:82. doi: 10.1186/1746-6148-9-82.
In classical scrapie, the disease-associated abnormal isoform (PrP(Sc)) of normal prion protein accumulates principally in the nervous system and lymphoid tissues of small ruminants. Lymph nodes traffic leukocytes via lymphatic and blood vasculatures but hemal nodes lack lymphatic vessels and thus traffic leukocytes only via the blood. Although PrP(Sc) accumulation profiles are well-characterized in ovine lymphoid tissues, there is limited information on such profiles in hemal nodes. Therefore, the objective of this study was to compare the follicular accumulation of PrP(Sc) within hemal nodes and lymph nodes by prion epitope mapping and western blot studies.
Our studies found that PrP(Sc) accumulation in 82% of animals' abdominal hemal nodes when PrP(Sc) is detected in both mesenteric and retropharyngeal lymph nodes collected from preclinical and clinical, naturally and experimentally (blood transfusion) scrapie-infected sheep representing all three major scrapie-susceptible Prnp genotypes. Abdominal hemal nodes and retropharyngeal lymph nodes were then used to analyze immune cell phenotypes and PrP(Sc) epitope mapping by immunohistochemistry and PrP(Sc) banding patterns by western blot. Similar patterns of PrP(Sc) accumulation were detected within the secondary follicles of hemal nodes and retropharyngeal lymph nodes, where cellular labeling was mostly associated with macrophages and follicular dendritic cells. The pattern of PrP(Sc) accumulation within hemal nodes and retropharyngeal lymph nodes also did not differ with respect to epitope mapping with seven mAbs (N-terminus, n = 4; globular domain, n = 2; C-terminus, n = 1) in all three Prnp genotypes. Western blot analysis of hemal node and retropharyngeal lymph node homogenates revealed identical three banding patterns of proteinase K resistant PrP(Sc).
Despite the anatomical difference in leukocyte trafficking between lymph nodes and hemal nodes, the follicles of hemal nodes appear to process PrP(Sc) similarly to lymph nodes.
在经典的瘙痒病中，正常朊病毒蛋白的疾病相关异常构象（PrP(Sc)）主要在小反刍动物的神经系统和淋巴组织中积累。淋巴结通过淋巴和血管系统运输白细胞，但血淋巴结缺乏淋巴管，因此只能通过血液运输白细胞。虽然在绵羊的淋巴组织中已经很好地描述了 PrP(Sc) 的积累模式，但关于血淋巴结中这种模式的信息有限。因此，本研究的目的是通过朊病毒表位作图和 Western blot 研究比较血淋巴结和淋巴节点中 PrP(Sc) 的滤泡积累。
我们的研究发现，当在来自临床前和临床、自然和实验（输血）感染瘙痒病的绵羊的肠系膜和咽后淋巴节点中均检测到 PrP(Sc) 时，82%的动物的腹部血淋巴结中积累了 PrP(Sc)，这些绵羊代表了三种主要的瘙痒病易感 Prnp 基因型。然后使用腹部血淋巴结和咽后淋巴节点来分析免疫细胞表型，并通过免疫组织化学进行 PrP(Sc) 表位作图，通过 Western blot 进行 PrP(Sc) 带型分析。在血淋巴结和咽后淋巴节点的次级滤泡中检测到类似的 PrP(Sc) 积累模式，其中细胞标记主要与巨噬细胞和滤泡树突状细胞相关。在所有三种 Prnp 基因型中，用七种 mAb（N 端，n = 4；球状结构域，n = 2；C 端，n = 1）进行表位作图时，血淋巴结和咽后淋巴节点中 PrP(Sc) 的积累模式也没有差异。对血淋巴结和咽后淋巴节点匀浆的 Western blot 分析显示，蛋白酶 K 抗性 PrP(Sc) 的三种带型模式完全相同。
尽管淋巴结和血淋巴结之间白细胞运输的解剖差异，但血淋巴结的滤泡似乎与淋巴结一样处理 PrP(Sc)。
