Zusman Itshak, Gurevich Pavel, Ben-Hur Herzl
Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
Int J Mol Med. 2005 Jul;16(1):127-33.
The role of protein components of the secretory immune system (SIS), such as the polymeric immunoglobulin receptor/secretory component (pIgR/SC), immunoglobulins (Igs) and joining (J) chain, in human intrauterine development was reviewed. These components are already present in 3.5- to 4-week-old embryos, and found in all tissues and organs of epithelial origin. The SIS is made up of two parts: the SIS of mucous membranes and their derivatives (mucosal or secretory immune system), and the SIS of barrier structures (barrier immune system). During organogenesis, SC disappears from the cells of organs that lose their exocrine Ig-secretion function, such as the hypophysis, pancreatic islands and adrenal glands. In cells and tissues of mesenchymal origin, SC is absent from the start, i.e. during their initial development. As examples of the barrier immune system, blood-tissue and tissue-tissue barriers, such as the chorion of the placenta, the epithelium of the choroid plexuses in the brain, as well as other barrier structures to Ig transfer were considered. Besides the SC and J chain, Fc receptors, cellular and tissue structures participate in this process. Three stages were described in Ig transfer: i) passing from the maternal blood into intervillous spaces and the trophoblast, ii) shifting in the intravillous stroma and its cells, and iii) excretion into embryonic (fetal) blood through the endothelium of the trophoblastic villous capillaries. Igs of maternal origin, mainly IgG and least abundant IgA, pass through the placental barrier in healthy embryos. Following a massive antigenic attack, the increased exocrine secretion of IgG, IgA, and IgM to a lesser extent, are already seen in embryos, reflecting increased functional activity of the SIS. Thus, in human intrauterine development, the SIS is a very early immune defensive system, which presents and acts before the appearance of the common lymphoid system.
本文综述了分泌免疫系统(SIS)的蛋白质成分,如多聚免疫球蛋白受体/分泌成分(pIgR/SC)、免疫球蛋白(Igs)和连接(J)链在人类子宫内发育中的作用。这些成分在3.5至4周龄的胚胎中就已存在,并存在于所有上皮来源的组织和器官中。SIS由两部分组成:粘膜及其衍生物的SIS(粘膜或分泌免疫系统)和屏障结构的SIS(屏障免疫系统)。在器官发生过程中,SC会从失去外分泌Ig分泌功能的器官细胞中消失,如垂体、胰岛和肾上腺。在间充质来源的细胞和组织中,从一开始,即在其初始发育过程中就不存在SC。作为屏障免疫系统的例子,考虑了血组织和组织-组织屏障,如胎盘绒毛膜、脑脉络丛上皮以及其他Ig转移的屏障结构。除了SC和J链外,Fc受体、细胞和组织结构也参与了这一过程。Ig转移过程分为三个阶段:i)从母体血液进入绒毛间隙和滋养层;ii)在绒毛间质及其细胞中转移;iii)通过滋养层绒毛毛细血管内皮排泄到胚胎(胎儿)血液中。在健康胚胎中,母体来源的Igs主要是IgG,最少的是IgA,穿过胎盘屏障。在遭受大量抗原攻击后,胚胎中IgG、IgA的外分泌分泌增加,IgM的增加程度较小,这反映了SIS功能活性的增强。因此,在人类子宫内发育过程中,SIS是一个非常早期的免疫防御系统,在普通淋巴系统出现之前就已存在并发挥作用。