A study of chemotaxis in the coelomocytes (blood cells) of Halocynthia roretzi

鉴于人类免疫系统的进化起源，海鞘的防御机制具有特殊的意义。为了探讨这一机制，我们在不同的实验条件下，用延时视频显微镜和扫描电镜观察了孤立海鞘的体腔细胞。该项目分为四个部分，将在下面分别描述。PRRT I：参考文献中描述的体腔细胞分类。细胞分为7种类型和1种亚型。PRRT II：检查腔黄细胞类型的吞噬活性。发现有三种类型的细胞吞噬羊红细胞，而一种类型的细胞只会将它们捆绑起来，并将它们交给其他类型的细胞。四种类型被证明含有碳颗粒。其中三种与上述相同，迅速排出颗粒，而另一种将颗粒积聚在细胞质中。PRRT III：显示化学引诱剂参与防御作用的间接证据。视频显微镜证据显示，两种类型的细胞被活体入侵者所吸引。其中一种被认为会释放出化学引诱剂。PRRT IV：诱导体腔细胞趋化的药物。在13种不同的溶液中，从微针的尖端应用于体腔细胞，7种诱导趋化。然而，没有一种已知的人类免疫系统化学引诱剂能诱导这种行为。

The defense mechanism of ascidians is of special interest in the light of the evolutionary origin of the hauman immune system. In an aim to investigate this mechanism, we have transferred the coelomocytes of the solitary ascidian in culture and observed them with time-lapse videomocroscopy and scanning electron microscopy under various experimental conditions.The project was persued in four parts which will be described separately below.PRRT I : Classification of the coelomocytes in reference to those described in literature. Seven types, and one subtype, of cells were distinguished.PRRT II : Examination of phagocytotic activity of the coelomocyte types.Three types were found to phagocytose sheep red blood cells, while one type only bundled and held them to hand them over to other cell types.Four types were shown to incorporate carbon particles. Three of these, the same as above, excreted the particles quickly while one accumulated them in its cytoplasm.PRRT III : Indirect evidence showing participation of chemoattractant(s) in the defense action.Video-microscopic evidence shows that two types of cells are attacted to the site of a living invader. One of them is considered to emit a chemoattractant.PRRT IV : Agents inducing chemotaxis in the coelomocytes.Among thirteen kinds of solutions applied to the coelomocytes from the tip of a microneedle, seven induced chemotaxis. however, none of known chemoattractant of human immune system tested induced such behavior.