Fasciola hepatica has been shown to have a high capacity for immunomodulation of the host response, making the development of protective vaccines extremely difficult. One of these immunomodulation mechanisms is the impairment of dendritic cells (DC) maturation and, therefore, suppression of antigenic presentation. The aim of this study was to evaluate the pathological changes as well as the characterization of two antigen presenting cells, DC (CD1b, CD83 and MHC-II positive) and follicular dendritic cells (FDC) (CNA.42, S100 and CD83 positive) by immunohistochemistry in the hepatic lymph nodes (HLN) and livers of sheep during the early stages of infection with F. hepatica [9 and 18 days post-infection (dpi)], compared with an uninfected group (UC) as a control. The results revealed a marked hyperplasia of HLN germinal centres at 9 and, in particular, 18 dpi, with respect to the UC group, with coincidental increased expression of CNA.42 in FDC of lymphoid follicles and CD1b in the DC of paracortical areas at 18 dpi. However, the expression of MHC-II and CD83 decreased at 9 and, particularly, at 18 dpi in HLN compared with that in the UC group. Since both markers are related to active presentation of antigens by DC and FDC, the results of the present study suggest that, despite the marked hyperplasia of HLN and increase in DC and FDC numbers during early stages of infection, the DC and FDC antigenic presentation capacity, as suggested by the expression of the markers MHC-II and CD83, is suppressed by the parasite. This suppression was not observed in the liver, probably because of the low number of DC. This is the first study of the immunophenotype of DCs and FDC in sheep infected with F. hepatica.

中文翻译：

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实验性感染Fasciola hepatica的绵羊的肝淋巴结和肝脏中树突状细胞和滤泡树突状细胞的特征。

已经证明肝片fasciola具有对宿主反应进行免疫调节的高能力，这使得开发保护性疫苗极为困难。这些免疫调节机制之一是损害树突状细胞（DC）成熟，因此抑制抗原呈递。这项研究的目的是评估两种抗原呈递细胞DC（CD1b，CD83和MHC-II阳性）和滤泡树突状细胞（FDC）（CNA.42，S100和CD83阳性）的病理变化以及特征与未感染组（UC）相比，免疫组化技术在感染F. hepatica的早期阶段[感染后9和18天（dpi）]对绵羊的肝淋巴结（HLN）和肝脏进行免疫组织化学检测。结果显示HLN生发中心在9岁时明显增生，相对于UC组，尤其是18 dpi，在18 dpi时，淋巴滤泡FDC中CNA.42的表达与皮层旁区DC中的CD1b同时增加。然而，与UC组相比，HLN中MHC-II和CD83的表达在9，特别是在18dpi时降低。由于这两种标记均与DC和FDC主动呈递抗原有关，因此本研究结果表明，尽管HLN明显增生并且在感染的早期阶段DC和FDC数量增加，但DC和FDC的抗原呈递能力如标记MHC-II和CD83的表达所暗示的，被寄生虫抑制。在肝脏中未观察到这种抑制作用，可能是因为DC的数量较少。