结核分枝杆菌纯蛋白衍生物（PPD）对CD4＋CD154＋T细胞的影响

目的通过研究结核分枝杆菌纯蛋白衍生物（PPD）对CD154＋ CD4＋T细胞亚群的影响，探讨结核分枝杆菌分泌蛋白的致病性。方法PPD或／和BCG刺激PBMCs后，用流式细胞术检测活动性肺结核的CD154＋ CD4＋T细胞和CD154＋ IFNγ＋T细胞的比例变化。结果①PPD刺激显著下调CD154＋ CD4＋T细胞比例，能够抑制BCG刺激产生的CD154＋ CD4＋T细胞的增殖；②PPD刺激CD154＋ CD4＋T细胞的效果显著低于BCG。结论PPD内存在能显著抑制机体保护性免疫的分泌蛋白，可能是结核杆菌进入人体后抑制机体免疫力的重要因素之一。

The impact of protein purified derivative on the population of CD4+CD154+T cell subset

Objective To study the impact of Mycobacterium tubereulosis（Mtb） protein purified derivative（PPD） on the population of CD4＋CD154＋ T cell subset and to investigate the pathogenicity of the secreted proteins of Mtb. Methods The CD4 ＋ CD154＋ T cells and the CD＋IFN-γ T cell subset were identified with flow cytometry and its population frequencies were examined in patients with pulmonary tuberculosis and controllers with positive PPD reaction after stimulating PBMCs with PPD or/and BCG. Results 1. PPD could significantly inhibit CD4 ＋ CD154＋T cell subset induced by BCG stimulation. 2. Compared with BCG, PPD was much less potent in stimulating the CD4＋ IFN-γ ＋ T cell subset. Conclusion Some secreted proteins in PPD can significantly suppress the T cell immunity to Mtb.