天花粉蛋白诱发CD8阳性细胞参与的人体免疫抑制

TRICHOSANTHJN IN INDUCING CD^(8+) T CELL-MEDIATED IMMUNE SUPPRESSION IN MAN

已证明0.05～5μg/ml 剂量范围内的天花粉蛋白对同种异体抗原、可溶性抗原、致分裂原诱发的人体淋巴细胞体外增殖的强烈抑制作用,与细胞裂解无关。本文提供的下列证据进一步表明,天花粉蛋白诱发的免疫低反应性属于免疫抑制:①经该蛋白脉冲处理过的 PBMC 照射后加到不含天花粉的培养组合中可抑制新鲜PBMC的增殖;②天花粉蛋白脉冲处理过的PBMC培养上清液显示抑制功能;③去除CD8阳性细胞抑制缓解;回加 CD8阳性细胞抑制再现,提示有CD8抑制性T细胞参与反应。

The proliferation of human lymphocytes treated with tetanus toxoid (TT) could be suppressed when Trichosanthin (Tk) was added to the culture medium. Instead of Tk itself, if the irradiated, Tk pulse-treated PBMCs were introduced into the culture, the TT-induced proliferation of fresh PBMCs could still be inhibited in a dose-dependent manner. The fact that immune low-responsiveness was thus transferred from the Tk-primed PBMCs excluded the posibility that the inhibition was caused by cytotoxcity or direct interrupion of protein synthesis in the cells since there was no Tk contained in the culture. Rather, the most possible mechanism leading to the inhibition was immune suppression, which was further confirmed by the observation that the super-natants collected from the TCS-primed PBMCs showed suppressive activity as well. Moreover, depleting CD8+ cells from the responding T population could diminish the suppression and adding back the same T subset into the culture restored the low-responsiveness, indicating the involvement of OD8 suppressor T cells in the suppression induced by Tk in human immune responses.