紫外线致弱日本血吸虫尾蚴感染小鼠引起的肺组织细胞反应及虫体扫描电镜观察

目的通过观察日本血吸虫(Schistosoma japonicum,Sj)紫外线辐照致弱尾蚴感染小鼠后肺组织的细胞反应以及肺期虫体的受损情况,探寻致弱尾蚴在小鼠体内诱导免疫效应机制和Sj受损情况。方法以紫外线致弱Sj尾蚴经腹部皮肤感染小鼠4d、7d、14d和45d后剖杀,分别取肺组织,固定、切片,光镜下观察虫体周围的组织细胞反应,并与同时期的感染小鼠组织切片进行比较,同时,对小鼠体内肺期Sj童虫进行扫描电镜观察。结果感染后4~7d,小鼠肺期童虫虫体周围出现较明显的出血灶和炎症反应,并有一定量的嗜酸性粒细胞、中性粒细胞、巨噬细胞等炎症细胞的浸润,同时期的正常感染小鼠组织内虫体周围炎症反应却不明显;虫体体壁可见不同程度的损伤,电镜观察显示小鼠体内的肺期童虫存在明显的畸形和发育延迟。结论紫外线辐照致弱尾蚴感染后Sj在小鼠体内不能正常发育成熟,和正常尾蚴相比,致弱尾蚴在肺期滞留时间较长,仅有极少数虫体可移行至肠系膜或肝脏,但宜不能发育成熟,引起的病理损害主要表现为在肺期弥漫性出血灶、炎症细胞浸润等反应,这些特征可能与血吸虫致弱尾蚴感染免疫机制有关。

The cellular reactions in pulmonary tissues of mice induced by the ultraviolet light-attenuated cecariae of Schisotsoma japonicum as observed by scanning electron microscopy

To observe the cellular reactions in lung tissues of mice and the damages induced in the pulmonary stages of worms in order to explore the mechanism of immune responses induced by the UV-attenuated cecariae, the cellular responses around scbistosomula in the lung tissues on day 4, 7, 14, and 45 days after infection of mice with UV-attenuated cecariae through abdominal skin were observed and compared under light microscope, and their tegument features were described. It was found that on day 4 and 7 post infection, the strong inflammatory reactions with marked hemorrhagic loci and inflammatory reactions with certain infiltration of eosinophils, neutrophils and macrophages around schistsomula were observed in the lung tissues of mice, and more inflammatory cells around the adult worms in the lung tissues could be demonstrated than those normally infected. The worm tegument ridges derived from the attenuated cecariae of the infected mice were disordered and their development was delayed. It is concluded that the development of the S. japonicum infected with UV-attenuated cecariae is delayed and its pathological changes are mainly limited in the lung tissues. Although certain attenuated worms can move to the liver stage, but few of them can develope into the normal adult worms. This condition may be related to the resistance mecha nism of infection in mice infected with attenuated cecariae.