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白血病自发缓解(spontaneous remission,SR)临床罕见,多认为与严重感染等因素有关,确切机制不详。浆样树突状细胞(pDC)和髓样树突状细胞(mDC)是机体调节免疫的重要细胞,分别发挥调节初始免疫和继发免疫的关键作用。在感染诱发的白血病SR患者中观察到pDC数量明显增多并伴有IFN-α水平升高,推测细菌感染激活了pDC,在SR中发挥重要作用。本研究旨在探讨细菌能否活化pDC并观察其功能。选择健康献血员及白血病SR患者,以梯度密度离心法分离获得外周血单个核细胞(PBMNC),应用免疫磁珠阴性选择及流式细胞阳性分选法,得到纯化的人pDC和mDC。将所得pDC分别与不同细菌共培育,利用流式细胞术及ELISA法检测共培育后细胞表面标志(CD40、CD86和HLA-DR)及细胞因子(IFN-α、IL-12、IFN-γ、IL-2、IL-4、IL-10)分泌水平的变化。结果表明:金葡菌、铜绿假单胞菌能激活pDC分泌大量IFN-α并促使初始CD4+T细胞向Th1分化。经细菌激活的pDC表面分子CD40、CD86表达明显增高,具有较强的刺激T细胞增殖能力。结论:金黄色葡萄球菌、铜绿假单胞菌细菌具有活化pDC的能力,活化的pDC能够产生大量干扰素,发挥初始免疫效应,提示细菌活化的pDC在感染诱导的白血病SR中可能发挥了重要作用。细菌活化pDC的确切机制尚需进一步研究。
Spontaneous remission of leukemia (spontaneous remission, SR) clinically rare, and that more serious infection and other factors, the exact mechanism is unknown. Plasma-like dendritic cells (DCs) and myeloid dendritic cells (mDCs) are important cells in the body to regulate immunity, playing a key role in regulating both primary and secondary immune responses. In patients with leukemia infection-induced leukemia observed a significant increase in the number of pDC accompanied by elevated levels of IFN-α, speculated that bacterial infection activated pDC play an important role in the SR. This study aimed to investigate whether bacteria can activate pDC and observe its function. Select healthy blood donors and leukemia patients with SR, isolated by gradient density centrifugation of peripheral blood mononuclear cells (PBMNC), the use of negative immunomagnetic beads and positive selection of flow cytometry to obtain purified human pDC and mDC. The obtained pDCs were co-cultured with different bacteria respectively. The expression of cell surface markers (CD40, CD86 and HLA-DR) and cytokines (IFN-α, IL-12 and IFN-γ, IL-2, IL-4, IL-10) secretion changes. The results showed that Staphylococcus aureus and Pseudomonas aeruginosa could activate pDC to secrete large amounts of IFN-α and induce initial CD4 + T cells to differentiate into Th1. Bacterially activated pDC surface molecules CD40, CD86 expression was significantly increased, with a strong ability to stimulate T cell proliferation. CONCLUSIONS: Staphylococcus aureus and Pseudomonas aeruginosa bacteria have the ability to activate pDC. The activated pDC can produce a large amount of interferon and exert an initial immune effect, suggesting that bacterially activated pDC may play an important role in infection-induced leukemia SR . The exact mechanism of bacterial activation of pDC needs further study.