Bodey Bela
Department of Pathology, Keck School of Medicine, University of Southern California, Childrens Center for Cancer and Blood Diseases, Childrens Hospital Los Angeles, Los Angeles, CA, USA.
Expert Opin Ther Targets. 2002 Feb;6(1):57-72. doi: 10.1517/14728222.6.1.57.
The thymus provides an optimal cellular and humoral microenvironment for a cell line committed differentiation of haematopoietic stem cells. The immigration process requires the secretion of at least one peptide, called thymotaxin, by cells of the reticulo-epithelial (RE) network of the thymic stromal cellular microenvironment. The thymic RE cells are functionally specialised based on their intrathymic location and this differentiation is modulated by various interaction signals of differentiating Thymocytes and other nonlymphatic, haematopoietic stem cells. The subcapsular, endocrine, RE cell layer is comprised of cells filled with periodic acid Shiff's-positive granules, which also express A2B5/TE4 cell surface antigens and MHC Class I (HLA A, B, C) molecules. Thymic nurse cells also produce thymosins beta 3 and beta 4 and display a neuroendocrine cell specific immunophenotype (IP): Thy-1+, A2B5+, TT+, TE4+, UJ13/A+, UJ127.11+, UJ167.11+, UJ181.4+ and presence of common leukocyte antigen (CLA+). Cortical RE cells express a surface antigen, gp200-MR6, which plays a significant role of thymocyte differentiation. Medullar RE cells display MHC Class II (HLA-DP, HLA-DQ, HLA-DR) molecule restriction. Thymic RE cells also produce numerous cytokines that are important in various stages of haematopoietic cell activation and differentiation. The co-existence of pituitary hormone and neuropeptide secretion, as well as the production of a number of interleukins and growth factors, and expression of receptors for all, by RE cells is an unique molecular biological phenomenon. Thymic neuroendocrine polypeptides are the source of self antigens presented by the MHC molecules to differentiating haematopoietic stem cells. On the level of individual RE cells, the numerous projections associated with a single cell, which engulf developing lymphocytes, nurturing and guiding them in their maturation, may differ in their hormone production and/or hormone receptor expression profile, thus allowing a single cell to be involved in distinct, separate steps of the T-cell and other haematopoietic cell maturation process. Thymic RE cells represent an important cellular and humoural network within the thymic microenvironment and are involved in the homeopathic regulation mechanisms of the multicellular organism. The intrathymic T-lymphocyte selection is a complex, multistep process, influenced by several functionally specialised RE cells and under immuno-neuroendocrine regulation control reflecting the dynamic changes of the mammalian organism.
胸腺为造血干细胞定向分化的细胞系提供了一个最佳的细胞和体液微环境。迁移过程需要胸腺基质细胞微环境的网状上皮（RE）网络细胞分泌至少一种称为胸腺趋化素的肽。胸腺RE细胞根据其在胸腺内的位置在功能上具有特异性，这种分化受到分化中的胸腺细胞和其他非淋巴造血干细胞的各种相互作用信号的调节。被膜下内分泌RE细胞层由充满过碘酸希夫氏阳性颗粒的细胞组成，这些细胞还表达A2B5/TE4细胞表面抗原和MHC I类（HLA A、B、C）分子。胸腺哺育细胞还产生胸腺素β3和β4，并表现出神经内分泌细胞特异性免疫表型（IP）：Thy-1+、A2B5+、TT+、TE4+、UJ13/A+、UJ127.11+、UJ167.11+、UJ181.4+以及共同白细胞抗原（CLA+）的存在。皮质RE细胞表达一种表面抗原gp200-MR6，其在胸腺细胞分化中起重要作用。髓质RE细胞表现出MHC II类（HLA-DP、HLA-DQ、HLA-DR）分子限制。胸腺RE细胞还产生多种细胞因子，这些细胞因子在造血细胞激活和分化的各个阶段都很重要。垂体激素和神经肽分泌的共存，以及多种白细胞介素和生长因子的产生，以及RE细胞对所有这些物质受体的表达，是一种独特的分子生物学现象。胸腺神经内分泌多肽是MHC分子呈递给分化中的造血干细胞的自身抗原的来源。在单个RE细胞水平上，与单个细胞相关的众多突起吞噬发育中的淋巴细胞，在其成熟过程中对其进行滋养和引导，这些突起在激素产生和/或激素受体表达谱方面可能有所不同，从而使单个细胞能够参与T细胞和其他造血细胞成熟过程中不同、独立的步骤。胸腺RE细胞代表胸腺微环境内一个重要的细胞和体液网络，并参与多细胞生物体的顺势调节机制。胸腺内T淋巴细胞的选择是一个复杂的多步骤过程，受到几种功能特异的RE细胞的影响，并处于免疫-神经内分泌调节控制之下，反映了哺乳动物机体的动态变化。
