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本研究探讨完整的血小板对骨髓来源的树突状细胞(BMDC)和肿瘤细胞的抗原呈递功能的影响。抗原呈递检测体系采用BMDC诱导的混合淋巴细胞反应或肿瘤细胞系EG7(表达卵白蛋白OVA)诱导的OVA特异性T细胞的活化,共培养体系中加入从小鼠外周血分离的血小板至不同浓度,培养一定时间后采用同位素掺入法检测淋巴细胞增殖,采用ELISA检测各种细胞因子的水平,采用流式细胞术检测细胞表面分子情况。结果发现,在反应体系中加入血小板时,淋巴细胞增殖和IFNγ产生均明显受抑制。血小板还可以阻断细菌脂多糖或含CpG基序的寡核苷酸引起的BMDC表面B7-2上调、细胞因子分泌及对同种异基因淋巴细胞的刺激反应。血小板也可抑制BMDC特异性T细胞呈递可溶性或细胞性抗原的能力,表现为淋巴细胞的增殖和细胞因子分泌受到抑制。血小板的这些抑制作用均依赖于加至培养体系中血小板的浓度。流式细胞术分析表明,血小板结合于BMDC仅轻微增加后者的死亡比例。结论:在某些条件下,血小板可以通过抑制抗原呈递功能而对免疫反应起到负向调控作用,血小板对免疫系统的调节可能比原来预期的更加复杂。
This study investigated the effect of intact platelets on the antigen presenting function of bone marrow-derived dendritic cells (BMDCs) and tumor cells. Antigen presentation detection system using BMDC-induced mixed lymphocyte reaction or tumor cell line EG7 (OVA expression of OVA) -induced activation of OVA-specific T cells in the co-culture system was added from the mouse peripheral blood platelets to different concentrations, culture After a certain period of time, the proliferation of lymphocytes was detected by isotope incorporation method. The levels of various cytokines were detected by ELISA, and the cell surface molecules were detected by flow cytometry. As a result, it was found that when platelets were added to the reaction system, lymphocyte proliferation and IFNγ production were significantly inhibited. Platelets can also block B7-2 upregulation of BMDC surface, secretion of cytokines and stimulation of allogeneic lymphocytes caused by bacterial lipopolysaccharide or CpG motif-containing oligonucleotides. Platelets also inhibit the ability of BMDC-specific T cells to present soluble or cellular antigens, as demonstrated by inhibition of lymphocyte proliferation and cytokine secretion. These inhibitory effects of platelets depend on the concentration of platelets added to the culture system. Flow cytometry analysis showed that platelet binding to BMDC increased the latter only slightly. CONCLUSIONS: Under certain conditions, platelets play a negative regulatory role in the immune response by inhibiting antigen presenting function, and regulation of the immune system by platelets may be more complex than previously thought.