T细胞活化促进B细胞产生抗体机制的研究

Dissection of molecular mechanisms on increased antibody production induced by activated T cells

B细胞活化和分化为抗体产生细胞的过程中,T细胞活化和T/B细胞相互作用的分子解析对研究自身抗体参与的自身免疫性疾病的发病机制和免疫干预具有重要的意义。为深入探讨人活化T细胞促进B细胞抗体产生的分子机制,我们建立CD4+T细胞和B细胞体外共培养体系,将活化CD4+T细胞和B细胞在体外共培养,测定不同时间培养上清液中IgG和IgM的水平,并通过抗体阻断实验分析参与B细胞抗体产生的重要分子。结果显示:CD4+T细胞在抗CD3/CD28抗体共同作用24h后即被活化,IL-2和IFN-γ的分泌明显增加,细胞表面黏附分子ICAM-1和诱导性协同刺激分子ICOS的表达强度显著增高;活化CD4+T细胞与B细胞共培养4d起,细胞培养上清液中可以检测到IgG和IgM,并随着共培养时间的延长而其量逐渐升高,抗ICAM-1抗体和抗ICOS抗体加入共培养体系可以明显降低培养上清液中IgG和IgM水平,其中抗ICAM-1抗体的阻断作用明显强于抗ICOS抗体。上述研究结果为人T细胞的活化促进B细胞抗体产生提供了重要证据,也为自身免疫病中T/B细胞相互作用的研究提供简便的实验方法和潜在的治疗靶点。

Molecular dissection of T cell activation and T/B interaction during B cell activation and differentiation will provideimportant clues to the study on pathogenesis of autoantibody-involved autoimmune diseases. To explore the molecular mechanisms of activated T cell-triggering B cell activation in human, we have established an in vitro co-culture system with CD4^＋ T cells and B cells. IgG and IgM levels in the supernatant were detected with two days＇ interval. The results indicated that with the stimulation of anti-CD3 and anti-CD28 antibodies, purified CD4^＋T cells were fully activated with the up-regulation of CD69 and HI.A-DR on T cell surface and high-level secretion of IL-2 and IFN-γ by activated CD4^＋ T cells. The expression of ICAM- 1 and ICOS also increased dramatically. After 4 days＇ co-culture, the levels of IgG and IgM in the supernatant increased until day 14 whereas there was very little IgG and IgM detectable with the co-culture of non-activated T cells and B cells. The addition of anti-ICAM-1 and anti-ICOS antibodies mostly blocked the production of IgG and IgM in which the blockade of ICAM-1 displayed more strong inhibitory effect. Our results thus provide direct evidence for the molecular mechanisms of T/B interaction during antibody production of B cell. The system we established also provides a practical and feasible in vitro Model for further study on the T/B interaction in the pathogenesis of autoimmune diseases as well as the screening of potential therapeutic targets of diseases.