Dessein A, Samuelson J C, Butterworth A E, Hogan M, Sherry B A, Vadas M A, David J R
Parasitology. 1981 Jun;82(Pt 3):357-74. doi: 10.1017/s0031182000066890.
Schistosomula of Schistosoma mansoni, recovered either after penetration of cercariae through isolated rat skin or by mechanical transformation of cercariae, become fully resistant after 24-48 h of culture to damage by human blood eosinophils in the presence of human anti-schistosomular sera. Cultured schistosomula are also shown to lose their susceptibility to attack by human eosinophils in the presence of human complement. This resistance is related to the simultaneous reduction of the ability of human anti-schistosomular antibodies and human complement component C3 to bind to the surface of the cultured larvae. The development of insusceptibility to antibody, complement and eosinophil-mediated attack does not require the acquisition by the schistosomula of a protective coat of host or other macromolecules, since it is achieved in chemically defined culture medium free of serum and macromolecules. This supports the hypothesis that schistosomula undergo intrinsic changes which render them insusceptible to immune attack.
曼氏血吸虫的童虫，无论是在尾蚴穿透离体大鼠皮肤后获得，还是通过尾蚴的机械转化获得，在培养24 - 48小时后，在人抗血吸虫童虫血清存在的情况下，对人血嗜酸性粒细胞的损伤变得完全有抵抗力。培养的童虫在人补体存在的情况下，对人嗜酸性粒细胞的攻击也表现出敏感性降低。这种抵抗力与同时降低人抗血吸虫抗体和人补体成分C3结合到培养幼虫表面的能力有关。对抗体、补体和嗜酸性粒细胞介导的攻击不敏感的发展不需要童虫获得宿主或其他大分子的保护涂层，因为这是在不含血清和大分子的化学成分确定的培养基中实现的。这支持了童虫经历内在变化从而使其对免疫攻击不敏感的假说。
