Ambrose N C, Riley J
Department of Biological Sciences, University of Dundee, Scotland.
Parasitology. 1988 Aug;97 ( Pt 1):27-42. doi: 10.1017/s0031182000066713.
The development of granulomatous reactions against moulting nymphal pentastomids (Porocephalus crotali) in the tissues of rat and mouse intermediate hosts is described. Adipose tissue and lungs are favoured sites for encystment accounting for 70% of larvae. Six moults separate the primary larva from the final infective stage which first appears about 80 days post-infection (p.i.) and is fully infective by day 120. Larvae, and particularly their cast cuticles, are the foci of granulomatous reactions characterized by an intense eosinophilia. During ecdysis, large numbers of eosinophils permeate the entire lesion but, significantly, degranulation is limited to the underside of cast cuticles where the resultant debris is endocytosed by macrophage/epithelioid cells. A pronounced asymmetry in the granulomatous lesion, evident even in the earliest cysts, results from the accumulation of individual epithelioid granulomas associated with cuticle fragments close to the ventral side of the developing parasite; each is circumscribed by fibrosis. External to this region are extensive tracts of tissue composed of mature plasma cells. Particularly in rats, large numbers of partially degranulated mast cells (= globule leucocytes) also surround cuticle granulomas, and mast cell granules can accumulate within macrophages and fibroblasts. Inflammation slowly subsides once the infective stage is attained. This 1 cm-long larva resides in a thin, fibrotic, C-shaped cyst and can remain viable for years: uniquely this instar retains its last moulted cuticle as a protective sheath. Nymphal instars II-VI feed predominantly upon eosinophils but we do not yet know whether this requirement is obligate.
本文描述了大鼠和小鼠中间宿主体内针对蜕皮若虫期舌形虫（猪巨吻棘头虫）的肉芽肿反应的发展情况。脂肪组织和肺是包囊形成的有利部位，占幼虫的70%。从初级幼虫到最终感染阶段需经过六次蜕皮，最终感染阶段最早在感染后约80天出现，到120天时完全具有感染性。幼虫，尤其是它们蜕下的角质层，是肉芽肿反应的病灶，其特征是强烈的嗜酸性粒细胞增多。在蜕皮过程中，大量嗜酸性粒细胞渗透到整个病变部位，但值得注意的是，脱颗粒仅限于蜕下的角质层底部，由此产生的碎片被巨噬细胞/上皮样细胞内吞。肉芽肿病变中明显的不对称性，即使在最早的囊肿中也很明显，这是由于与发育中寄生虫腹侧附近角质层碎片相关的单个上皮样肉芽肿的积累所致；每个肉芽肿都被纤维化所包围。在这个区域之外是由成熟浆细胞组成的广泛组织区域。特别是在大鼠中，大量部分脱颗粒的肥大细胞（=球状白细胞）也围绕着角质层肉芽肿，肥大细胞颗粒可在巨噬细胞和成纤维细胞内积聚。一旦达到感染阶段，炎症就会慢慢消退。这种1厘米长的幼虫栖息在一个薄的、纤维化的C形囊肿中，可以存活数年：独特的是，这一龄期保留其最后一次蜕下的角质层作为保护鞘。若虫II-VI龄主要以嗜酸性粒细胞为食，但我们尚不知道这种需求是否是必需的。
