Pezzano M, Li Y, Philp D, Omene C, Cantey M, Saunders G, Guyden J C
Department of Biology, City College of New York, New York 10031, USA.
Cell Mol Biol (Noisy-le-grand). 1995 Dec;41(8):1099-111.
We have now developed temperature sensitive lines of thymic nurse cells (TNCs), using the SV40 viral mutant tsA58, that maintain the ability to selectively internalize a subpopulation of alpha beta TCR+CD4+CD8+ thymocytes in vitro. One line, tsTNC-1, was shown to be able to rescue a subset of CD4+CD8+ thymocytes from programmed cell death at 32 degrees C, the temperature at which binding and internalization were detected. Rescue was significantly diminished at 38 degrees C, the temperature at which thymocyte binding was not observed. The rescued population of thymocytes showed a reduced level of apoptosis as measured by the DNA fragmentation assay. TNC rescue resulted in a shift of CD4+CD8+ thymocytes from immature TCRlow PNArhigh cells to the more mature TCRint PNArlow phenotype but no changes in cell surface levels of HSA nor CD69 were detected. The rescue activity of tsTNC-1 cells at 32 degrees C was significantly reduced with the addition of antibodies to either class I or class II MHC antigens. These results suggest that we have established TNC lines, using the SV40 viral mutant tsA58, that have the ability to rescue a subset of the TNC interactive thymocyte population from programmed cell death. The thymocyte population rescued by TNCs matures to a phenotype within the double positive stage of development that is indicative of positive selection.
我们现在利用SV40病毒突变体tsA58开发了温度敏感型胸腺哺育细胞（TNCs）系，该细胞系在体外保持了选择性内化αβ TCR+CD4+CD8+胸腺细胞亚群的能力。其中一个细胞系tsTNC-1被证明能够在32℃（检测到结合和内化的温度）下从程序性细胞死亡中拯救一部分CD4+CD8+胸腺细胞。在38℃（未观察到胸腺细胞结合的温度）下，拯救作用显著减弱。通过DNA片段化分析测量，被拯救的胸腺细胞群体显示出较低水平的细胞凋亡。TNC拯救导致CD4+CD8+胸腺细胞从未成熟的TCRlow PNArhigh细胞转变为更成熟的TCRint PNArlow表型，但未检测到细胞表面HSA和CD69水平的变化。添加针对I类或II类MHC抗原的抗体后，tsTNC-1细胞在32℃下的拯救活性显著降低。这些结果表明，我们利用SV40病毒突变体tsA58建立了TNC系，该细胞系有能力从程序性细胞死亡中拯救一部分与TNC相互作用的胸腺细胞群体。被TNCs拯救的胸腺细胞群体在发育的双阳性阶段成熟为一种表型，这表明发生了阳性选择。
