天花粉蛋白通过激活CD8 Tc2亚群诱导人体免疫抑制

为了探讨天花粉蛋白(Tk)诱导免疫抑制的机制,采用抗原非特异性T淋巴母细胞增殖系统,筛选了37个Tk致敏的抑制性T细胞系。分析表明,健康人体内Tk相关抑制性T细胞的频率为5.0×10-7～10.8×10-7,该细胞系属CD8+TCRαβ+,细胞因子表达格局呈现向IL-4和IL-10明显偏移和IFN-γ分泌明显下降的格局。结合我们已有关于CD8+T细胞介导Tk相关应答而不显示细胞毒性的工作,可从表型和功能分析上确认,Tk针对体外人体淋巴细胞增值的免疫抑制,由CD8Tc2细胞介导。

Trichosanthin induces human immune suppression via activation of CD8 Tc2 subset

To elucidate the mechanisms underlying the Trichosanthin (Tk),induced human immune suppression, 37 Tk,primed T cell lines were established based on their ability of inducing hyporeactions to PHA,induced lymphoproliferation. With frequencies 5.0×10-7～ 10.8×10-7 in health subjects, the Tk,primed suppressor T cells were characterized as CD8+ TCRαβ+ with a type 2 cytokines (IL,4 and IL,10) secreting pattern. In contrast, the production of type 1 cytokine IFN,γ was remarkably depressed. Together with our previous observations that the Tk,induced suppression could be significantly diminished when CD8 cells were depleted from the total T cells and the depleted CD8+ T cells failed to show any cytotoxic activity. It is concluded that the suppression induced by Tk on human lymphoproliferation is mediated by the activation of CD8 Tc2 subset.