Murray A M, Simm B, Beagley K W
Discipline of Pathology, University of Newcastle, NSW, Australia.
Cytokine. 1998 May;10(5):337-45. doi: 10.1006/cyto.1997.0302.
An increasing body of evidence suggests that certain T cell subsets mature extrathymically in the epithelium of the intestine. In the studies reported here, the authors have analysed cytokine/growth factor gene expression, recombinase-activating gene RAG-1 and RAG-2 gene expression and terminal deoxynucleotidyl transferase (TdT) gene expression in mouse fetal intestine and fetal thymus and liver, two known haematopoietic tissues. Stem cell factor (SCF) and interleukin 7 (IL-7) message was abundant in all three tissues during fetal development. IL-2 and IL-4 were not expressed in fetal gut but IL-4 was weakly detected in fetal liver and thymus. IL-9 and IL-13 mRNA was detected in all fetal tissues and IL-15 mRNA was abundant in fetal intestine but only weakly expressed in fetal liver and thymus. mRNA for SCF, IL-7, IL-13 and IL-15 was also detected in fibroblast-like cell lines derived from fetal intestine. RAG-1 and RAG-2 mRNA was detected in all three fetal tissues. TdT mRNA was not detected in fetal gut or liver but was weakly expressed in (fetal day) fd19-20 fetal thymus. Long-term (> 6 weeks) in vitro growth of IEL was achieved by coculturing intraepithelial lymphocytes (IEL) with IL-7-secreting fibroblasts in the presence of SCF and IL-2. The data show that the fetal mouse gut provides a suitable environment for lymphocyte development and receptor rearrangement, similar to fetal thymus and liver, even though expansion of intestinal IEL is delayed until 2-3 weeks after birth.
越来越多的证据表明，某些T细胞亚群在肠道上皮中进行胸腺外成熟。在本文报道的研究中，作者分析了细胞因子/生长因子基因表达、重组酶激活基因RAG - 1和RAG - 2基因表达以及末端脱氧核苷酸转移酶（TdT）基因在小鼠胎儿肠道、胎儿胸腺和肝脏（两种已知的造血组织）中的表达。在胎儿发育过程中，干细胞因子（SCF）和白细胞介素7（IL - 7）的信息在所有这三种组织中都很丰富。IL - 2和IL - 4在胎儿肠道中不表达，但在胎儿肝脏和胸腺中可微弱检测到IL - 4。在所有胎儿组织中均检测到IL - 9和IL - 13 mRNA，IL - 15 mRNA在胎儿肠道中丰富，但在胎儿肝脏和胸腺中仅微弱表达。在源自胎儿肠道的成纤维细胞样细胞系中也检测到了SCF、IL - 7、IL - 13和IL - 15的mRNA。在所有三种胎儿组织中均检测到RAG - 1和RAG - 2 mRNA。在胎儿肠道或肝脏中未检测到TdT mRNA，但在（胎儿日）fd19 - 20的胎儿胸腺中微弱表达。通过在SCF和IL - 2存在的情况下，将上皮内淋巴细胞（IEL）与分泌IL - 7的成纤维细胞共培养，实现了IEL的长期（> 6周）体外生长。数据表明，胎儿小鼠肠道为淋巴细胞发育和受体重排提供了一个合适的环境，类似于胎儿胸腺和肝脏，尽管肠道IEL的扩增会延迟到出生后2 - 3周。
