Intracellular signal transduction of activated T cells and anergic T cells

当用细菌超抗原刺激时，根据T细胞成熟或亚群，人T细胞显示不同的生物学应答。我们通过比较信号转导的方式来解决T细胞为什么以不同的方式应答的问题.处于胸腺成熟末期的人胸腺CD 1a ^-CD 4 ^+ T细胞对细菌超抗原诱导的无反应性敏感，而成人外周血（APB）CD 4 ^+ T细胞不仅被诱导至无反应性状态，而且在再刺激时表现出高反应性。在再刺激后，APB CD 4 ^+ T细胞原始细胞中lck的酪氨酸激酶活性增加，但在胸腺CD 4 ^+ T细胞原始细胞中不增加。Lck是高度酪氨酸磷酸化的两种类型的T细胞母细胞再刺激前。再刺激后，APB CD 4 ^+ T细胞母细胞中该蛋白明显去磷酸化，但胸腺CD 4 ^+ T细胞母细胞中没有。共聚焦显微镜显示，在再刺激的APB CD 4 ^+ T细胞母细胞中，Lck和CD 45共定位被诱导，但在胸腺CD 4 ^+ T细胞母细胞中不诱导。此外，在再刺激的APB CD 4 ^+ T细胞母细胞中观察到Lck在膜筏中显著蓄积，但在胸腺CD 4 ^+ T细胞母细胞中未观察到。这些数据表明Lck和CD 45之间的相互作用对于T细胞活化是重要的，并且这种相互作用在胸腺CD 4 ^+ T细胞母细胞中受到物理抑制，并且在维持无反应性状态中起关键作用。接下来，我们在体外检测了超抗原诱导的APB CD 4 ^+和CD 8 ^+ T细胞亚群的应答。CD 4 ^+ T细胞亚群的增殖反应和IL-2/IL-4的产生高于CD 8 ^+ T细胞亚群，而CD 8 ^+ T细胞亚群的IFN-γ产生和对MHC II^+细胞的细胞毒活性高于CD 4 ^+ T细胞亚群。这些数据表明，CD 4 ^+和CD 8 ^+ 1-细胞亚群被细菌超抗原以特定方式激活。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.