Signal transduction of negative selection in human thymus

针对CD 4 + CD 8+：双阳性（DP）细胞进行阴性选择;消除自身反应性T细胞。通过T细胞受体（TCR）介导的强信号诱导凋亡因子的产生，最终杀伤并清除靶细胞，建立了抗CD 3抗体和抗CD 28抗体对人DP细胞的体外阴性选择模型。用抗CD 3和抗CD 28抗体标记的DP细胞死亡，显示胰腺炎的特征，如Annexin V阳性，Caspase 3被激活。在此过程中，观察到线粒体δ-psi的丢失。在细胞凋亡信号转导中，细胞色素c、AIF、Smac、核酸内切酶G、HtrA 2等多种蛋白质从线粒体膜间隙释放到细胞质中。用流式细胞仪检测抗CD 3和抗CD 28抗体处理DP细胞后，这些蛋白在细胞内分布的变化。细胞色素c和AIF不定位于胞浆，但在处理的DP细胞中，细胞色素c和AIF的胞浆浓度升高，我们认为线粒体在负选择的人胸腺细胞凋亡信号转导中起作用。

The negative selection ; the elimination of auto reactive T cell, is executed against CD4+CD8+ : double positive (DP) cells. The apoptotic factors were induced following the strong signal through T cell receptor (TCR) and finally the targeted cells were killed and eliminatedWe set up the in vitro negative selection model using anti-CD3 antibody and anti-CD28 antibody to human DP cell. The DP cell that was trated by anti-CD3 and anti-CD28 antibody falled to death showing the characteristic feature of apoptois such as the Annexin V was proved to positive and Caspase 3 was activated. In this process, the loss of mitochondrial delta-psi was obsereved. We investigated that the mitochondria act the key role in T cell negative selection.In the apoptotic signal transduction, various protein such as cytochrome c, AIF, Smac, Endonuclease G, and HtrA2 was released from mitochondrial intermembrane space into cytoplasm. We studied the change of the intracellular distribution of these proteins using the flowcytometry in anti-CD3 and anti-CD28 antibody treated DP cell. Cytochrome c or AIF is not localysed in cytoplasm, but the elevation of the cytoplasmic concentration of cytochrome c or AIF was observed in treated DP cell.From these result, we consider that the mitochondria is act in the apoptotic signal transduction of the negative selection in human thymus.