Rombout J H, Lamers C H, Helfrich M H, Dekker A, Taverne-Thiele J J
Cell Tissue Res. 1985;239(3):519-30. doi: 10.1007/BF00219230.
Two protein antigens, horseradish peroxidase (HRP) and ferritin, have been administered to the digestive tract of carp. Electron-microscopical observations reveal considerable absorption of both antigens in the second segment of the gut (from 70 to 95% of the total length) and also, although to a lesser extent, in the first segment (from 0 to 70% of the total length). Even when administered physiologically with food, a large amount of ferritin is absorbed by enterocytes in the second gut segment. HRP and ferritin are processed by enterocytes in different ways. HRP seems to adhere to the apical cell membrane, probably by binding to receptors, and is transported in vesicles to branched endings of lamellar infoldings of the lateral and basal cell membrane. Consequently, most of the HRP is released in the intercellular space where it contacts intra-epithelial lymphoid cells. Only small amounts of HRP become localized in secondary lysosomes of enterocytes. Ferritin does not bind to the apical cell membrane; after uptake by pinocytosis, it is present in small vesicles or vacuoles that appear to fuse with lysosome-like-bodies. In the second segment, intact ferritin ends up in the large supranuclear vacuoles (after 8 h), where it is digested slowly. Although no ferritin is found in the intercellular space, ferritin-containing macrophages are present between the epithelial cells, in the lamina propria and also to a small extent in the spleen. The transport of antigens from the intestinal lumen, through enterocytes, to intra-epithelial lymphoid cells or macrophages may have immunological implications, such as induction of a local immune response and prospectives for oral vaccination.
已将两种蛋白质抗原，即辣根过氧化物酶（HRP）和铁蛋白，施用于鲤鱼的消化道。电子显微镜观察显示，两种抗原在肠道的第二段（占总长度的70%至95%）均有大量吸收，在第一段（占总长度的0%至70%）也有吸收，不过程度较轻。即使与食物一起生理给药，大量铁蛋白仍被第二段肠道中的肠细胞吸收。HRP和铁蛋白在肠细胞中的处理方式不同。HRP似乎粘附于顶端细胞膜，可能是通过与受体结合，并通过囊泡运输至外侧和基底细胞膜片状褶皱的分支末端。因此，大部分HRP释放到细胞间隙中，在那里它与上皮内淋巴细胞接触。只有少量HRP定位于肠细胞的次级溶酶体中。铁蛋白不与顶端细胞膜结合；通过胞饮作用摄取后，它存在于小囊泡或液泡中，这些囊泡或液泡似乎与溶酶体样小体融合。在第二段中，完整的铁蛋白最终进入大的核上液泡（8小时后），在那里它被缓慢消化。尽管在细胞间隙中未发现铁蛋白，但含铁血黄素巨噬细胞存在于上皮细胞之间、固有层中，在脾脏中也有少量存在。抗原从肠腔通过肠细胞运输到上皮内淋巴细胞或巨噬细胞可能具有免疫学意义，例如诱导局部免疫反应以及口服疫苗的前景。
