Department of Immunology, IDEHU-National Research Council, University of Buenos Aires, Argentina.
Cell Tissue Res. 2010 Mar;339(3):597-611. doi: 10.1007/s00441-009-0912-9. Epub 2010 Feb 1.
Sipunculans, a small phylum of coelomated marine worms closely related to polychaete annelids, lack a true circulatory system. We have previously shown that the sipunculan Themiste petricola can form a cellular clot, without congealing, of cell-free coelomic fluid. The clot is formed by the aggregation of large granular leukocytes (LGLs) and may serve not only haemostatic but immune functions, since dissimilar particles may become entrapped within it. We have now evaluated the capacity of a massive clot, induced in vitro by sea water contact, to stop coelomic fluid flow. We have further studied smaller clots induced on glass-slides either with or without the presence of bacteria placed for entrapment within the clot. The fate of clotting LGLs is cell death while forming a cohesive mass, although cytoplasmic and nuclear remnants are shed from the clot. These remnants and any bacteria that avoid clot entrapment or are detached from the clot are engulfed by non-clotting cells that include small granular leukocytes (SGLs) and large hyaline amebocytes (LHAs). Both cell types can be found other than in the clot but SGLs also occur around the clot edges heavily loaded with engulfed material. The cytoskeletal arrangement of SGLs evaluated with phalloidin-rhodamine correspond to motile cells and contrast with that of clotting LGLs that form a massive network of F-actin. Thus, the complementary roles between clotting LGLs and non-clotting SGLs and LHAs act a central immune strategy of Themiste petricola to deal with body wall injury and pathogen intrusion into the coelomic cavity.
星虫，是一类与多毛环节动物密切相关的体腔海洋蠕虫，缺乏真正的循环系统。我们之前已经表明，星虫 Themiste petricola 可以在没有凝结的情况下，从无细胞体腔液中形成一种细胞性凝块。凝块是由大颗粒白细胞（LGL）聚集形成的，它不仅可以发挥止血作用，还具有免疫功能，因为不同的颗粒可能会被包裹在其中。现在，我们评估了体外通过接触海水诱导的大量凝块阻止体腔液流动的能力。我们还进一步研究了在玻璃载玻片上诱导的较小凝块，这些凝块要么在没有放置细菌的情况下形成，要么在放置细菌的情况下形成，以便被包裹在凝块中。形成凝聚体的 LGL 的命运是细胞死亡，尽管细胞质和核碎片从凝块中脱落。这些碎片和任何避免凝块捕获或从凝块上脱落的细菌都会被非凝块细胞吞噬，这些细胞包括小颗粒白细胞（SGL）和大透明阿米巴细胞（LHA）。这两种细胞类型都可以在凝块之外找到，但 SGL 也存在于凝块边缘，那里有大量被吞噬的物质。用鬼笔环肽-罗丹明评估的 SGL 的细胞骨架排列与运动细胞相对应，而与形成 F-肌动蛋白大量网络的凝结 LGL 形成鲜明对比。因此，凝结 LGL 和非凝结 SGL 和 LHA 之间的互补作用是 Themiste petricola 应对体壁损伤和病原体侵入体腔的核心免疫策略。
