摘要目的 研究超抗原金黄葡萄球菌A型肠毒素(SEA)在体内诱导的体液免疫反应、T淋巴细胞增殖及免疫无应答的规律和作用.方法 利用重组SEA蛋白免疫小鼠,酶联免疫吸咐试验(ELISA)检测特异性抗体及其亚类水平,观察两者的产生过程及变化规律.RT-PCR反应检测免疫后小鼠脾脏内细胞因子的mRNA表达水平,EUSPOT法检测rSEA对脾细胞分泌IFN-γ能力的影响,流式细胞术检测T淋巴细胞表面抑制性受体PD-1的表达.结果 BALB/c小鼠在低剂量的rSEA初次免疫后2周,即产生了高水平的特异性抗体,此时体内以体液免疫应答为主,IgG2a/IgG1＜1;而在免疫早期,Th1型细胞因子的mRNA表达水平高于Th2型,以细胞免疫应答为主.短时期内进行再次免疫后脾细胞的IFN-γ分泌频率显著下降;流式细胞仪在rSEA激活的T淋巴细胞表面检测到了PD-1(programmed death-1)分子的表达,其表达量随时间及免疫次数增加.结论 超抗原SEA初次免疫即能引起强大的体液免疫应答与细胞免疫应答;再次免疫引起了免疫无应答,这与PD-1介导的抑制作用增强有关.

abstractsObjective To observe the effects of superantigen-induced humoral immunity,T cells proliferation and anergy in vivo.Methods ELISA was used to detect the specific antibodies IgG,IgG1 and IgG2a in serum of mice induced by recombinant staphylococcal enterotoxin A(rSEA).The mRNA expression of cytokines in spleen cells was examined by RT-PCR.Antigen-specific IFN-γ production was assayed using the ELISPOT kit and the expression of inhibitory receptor PD-1 was determinated by FCM.Results BALB/c mice intraoeritoneal immunized with the rSEA producted high level of rSEA-special antibody and induced T lymphocyte proliferation which has differentiation with type ⅠorⅡ T cells.The average frequency of specific IFN-γ producing cells in spleens did not increase when immunized again with rSEA in a short time.The expression of PD-1 molecular on spleen T cells were different in each group.Condusion Humoral immunity and T cells proliferation can be induced significantly by rSEA.The expression of PD-1 is likely responsible for the induction and maintenance of T cells anergy induced by superantigen rSEA.