Intracellular signal transduction of activated T cells and anergic T cells

当细菌超抗原刺激时，人类T细胞根据T细胞成熟或亚群表现出不同的生物学反应。我们通过比较信号转导解决了为什么T细胞以不同的方式反应的问题。人胸腺CD1a^-CD4^+ T细胞在胸腺成熟的最后阶段易受细菌超抗原诱导的能态，而成人外周血（APB） CD4^+ T细胞不仅被诱导成无能状态，而且在再刺激下表现出高反应。APB CD4^+ t细胞再刺激后，ck酪氨酸激酶活性升高，胸腺CD4^+ t细胞再刺激后ck酪氨酸激酶活性不升高。在再刺激之前，两种类型的t细胞胚中Lck都高度酪氨酸磷酸化。再刺激后，APB CD4^+ t细胞细胞明显去磷酸化，而胸腺CD4^+ t细胞细胞不明显。共聚焦显微镜显示，Lck和CD45的共定位在再刺激的APB CD4^+ t细胞细胞中被诱导，但在胸腺CD4^+ t细胞细胞中没有被诱导。此外，在APB CD4^+ t细胞中观察到膜筏中显著的Lck积累，而在胸腺CD4^+ t细胞中则没有。这些数据表明Lck和CD45之间的相互作用对于T细胞的激活是重要的，并且这种相互作用在胸腺CD4^+ T细胞母细胞中被物理抑制，并在维持无能状态中起关键作用。接下来，我们在体外检测了超抗原诱导的APB CD4^+和CD8^+ t细胞亚群的反应。CD4^+ t细胞亚群的增殖反应和IL-2/IL-4产生高于CD8^+ t细胞亚群，而MHC II类细胞的IFN-y产生和细胞毒活性在CD8^+亚群中高于CD4^+亚群。这些数据表明CD4^+和CD8^+ 1细胞亚群被细菌超级抗原以特定的方式激活。现在我们试图证实Lck调节与不同的反应有关。

Human T cells show different biological responses according to T-cell maturation or subsets when stimulated with bacterial superantigens. We addressed the question why the T cells response in different way by comparing signal transduction.1. Human thymic CD1a^-CD4^+ T cells in the final stage of thymic maturation are susceptible to anergy induced by bacterial superantigens, whereas adult peripheral blood (APB) CD4^+ T cell are not only induced to anergic state but also exhibit high responses by restimulation. The tyrosine kinase activity of lck increased after restimulation in APB CD4^+ T-cell blasts but not in thymic CD4^+ T-cell blasts. The Lck was highly tyrosinphosphorylated in both types of T-cell blasts before restimulation. After restimulation, it was markedly dephosphorylated in APB CD4^+ T-cell blasts but not in thymic CD4^+ T-cell blasts. Confocal microscopy demonstrated that colocalization of Lck and CD45 was induced in restimulated APB CD4^+ T-cell blasts but not in thymic CD4^+ T-cell blasts. Further, remarkable accumulation of Lck in the membrane raft was observed in restimulated APB CD4^+ T-cell blasts but not in thymic CD4^+ T-cell blasts. These data indicate that interaction between Lck and CD45 is important for T- cell activation and that the interaction is suppressed physically in thymic CD4^+ T-cell blasts and plays a critical role in sustaining an anergic state.2. Next, we examined superantigen-induced responses of APB CD4^+ and CD8^+ T-cell subsets in vitro. The proliferative response and IL-2/IL-4 production were higher in CD4^+ T-cell subset than in CD8^+ T-cell subset, while IFN-y production and cytotoxic activity on MHC class II^+ cells were higher in the CD8^+ subset than in the CD4^+ subset. These data indicate that CD4^+ and CD8^+ 1-cell subsets are activated by bacterial superantigens in specific ways. Now we try to confirm that Lck regulation is related with the different responses.