Leene W, de Waal Malefijt R, Roholl P J, Hoeben K A
Laboratory of Histology and Cell Biology, University of Amsterdam, The Netherlands.
Cell Tissue Res. 1988 Jul;253(1):61-8. doi: 10.1007/BF00221740.
In situ pre-existing complexes of epithelial cells and thymocytes having thymic nurse cell characteristics were visualized in the murine thymus cortex using dexamethasone as a potent killer of cortisone-sensitive thymocytes. The degradation and subsequent depletion of cortisone-sensitive thymocytes enclosed within cortical epithelial cells appeared to be paralleled by thymocyte degradation and depletion in thymic nurse cells isolated from thymic tissue fragments from dexamethasone-treated animals. This suggests that thymic nurse cells are derived from pre-existing sealed complexes of cortical epithelial cells and thymocytes. Not all thymocytes situated within in situ epithelial or thymic nurse cells complexes appear to be cortisone-sensitive: a minority of 1-2 thymocytes per complex survives the dexamethasone-treatment, thus constituting a minor subset of cortical cortisone-resistant thymocytes predominantly localized within cortical epithelial cells in situ and within thymic nurse cells derived from such structures. Cortisone resistance in thymocytes thus seems to be acquired within the cortical epithelial cell microenvironment. Cortisone-resistant thymocytes in thymic nurse cells express the phenotype of mature precursors of the T helper lineage, indicating that the in situ correlates of thymic nurse cells may play an important role in T cell maturation and selection.
利用地塞米松作为对可的松敏感的胸腺细胞的强效杀手，在小鼠胸腺皮质中可视化了具有胸腺哺育细胞特征的上皮细胞和胸腺细胞的原位预先存在的复合体。包被在皮质上皮细胞内的对可的松敏感的胸腺细胞的降解及随后的耗竭，似乎与从地塞米松处理动物的胸腺组织片段分离出的胸腺哺育细胞中的胸腺细胞降解和耗竭同时发生。这表明胸腺哺育细胞源自皮质上皮细胞和胸腺细胞预先存在的封闭复合体。并非所有位于原位上皮或胸腺哺育细胞复合体内的胸腺细胞似乎都对可的松敏感：每个复合体中有少数1 - 2个胸腺细胞在地塞米松处理后存活下来，从而构成了主要定位于原位皮质上皮细胞内以及源自此类结构的胸腺哺育细胞内的皮质抗可的松胸腺细胞的一个小亚群。因此，胸腺细胞中的可的松抗性似乎是在皮质上皮细胞微环境中获得的。胸腺哺育细胞中的抗可的松胸腺细胞表达T辅助细胞系成熟前体的表型，表明胸腺哺育细胞的原位对应物可能在T细胞成熟和选择中起重要作用。
