大黄鱼白细胞介素-21调控淋巴细胞增殖与分化的功能及信号通路研究

哺乳类白细胞介素-21（IL-21）是主要由T细胞分泌的细胞因子，在调控T/B细胞增殖分化、浆细胞形成及抗体产生过程中发挥重要作用。然而，鱼类IL-21是否具有同样的功能目前尚不明确。前期我们证明了重组大黄鱼IL-21蛋白可在体内促进T细胞增殖，并建立了IgM+/IgT+ B细胞分选技术。本项目拟进一步研究大黄鱼IL-21体外促进T细胞增殖与分化的功能；用重组CD40L蛋白和CpG为B细胞提供T细胞依赖/非依赖（TD/TI）抗原活化信号，研究IL-21在TD/TI抗原活化的IgM+和IgT+ B细胞存活、增殖、分化为浆细胞及抗体产生过程中的功能；利用免疫共沉淀鉴定IL-21的受体及其下游信号分子，进而通过信号通路抑制和受体封阻明确大黄鱼IL-21激活的信号通路。研究结果对于认识大黄鱼IL-21在调控适应性免疫中的功能具有重要的理论意义，也为将其作为免疫佐剂应用于大黄鱼病害防治提供理论依据。

In mammals, interleukin-21 (IL-21) is mainly secreted by T cells. It plays crucial roles in regulating the T/B cells proliferation, differentiation, plasma cells generation and antibody production. However, little is known about the function of teleost IL-21 in these biological process currently. In preliminary study, we found the recombinant LcIL-21 (rLcIL-21) protein could significantly promote the proliferation of T cells in vivo, and have established the techniques of IgM+/IgT+ B cells assorting and isolation. In this research, the exact function of LcIL-21 on T cells proliferation and differentiation in vitro will be investigated. Recombinant LcCD40L protein and CpG will be respectively used as the T cell-dependent (TD)/-independent (TI) antigen activation signal for both IgM+ and IgT+ B cells. The effect of LcIL-21 on the TD/TI antigen activated B cells survival, proliferation, differentiation into plasma cells and antibody production will also be investigated. Specific receptors of LcIL-21 and signal molecules of LcIL-21 signal pathways will be identified by Co-immunoprecipitation. Signaling pathway inhibition and IL-21R blocking experiment will also be performed to further reveal the signaling pathways activated by LcIL-21. These results will not only help to reveal the function of LcIL-21 in regulating adapt immune response, but also provide theoretical basis for the future application of LcIL-21 as immune adjuvant in the disease prevention of large yellow croaker.