胞壁表达Der p2的重组BCG对BALB/c小鼠Th细胞免疫应答的影响

The effects of rBCG expressing Der p2 in the form of lipoprotein on murine immune response

目的:观察接种以膜蛋白形式表达屋尘螨抗原Der-p2基因的重组BCG(rBCG),对BALB/c小鼠Th细胞免疫应答的影响。方法:以生理盐水为对照,分别将rBCG和BCG经腹腔注射接种于6～8wk龄和新生BALB/c小鼠,用ELISA法测定小鼠血清、脾脏T细胞培养上清(STLCS)中IL4、IFN-γ水平,用双色荧光标记流式细胞仪法测定脾脏细胞Th细胞亚群。结果:接种rBCG和BCG后,成年和新生小鼠血清和STLCS中IL4水平较对照组显著降低、IFN-γ水平显著升高;无论成年鼠还是新生鼠,在CD4+的脾脏细胞中,IFN-γ+细胞的比例明显升高,而IL4+细胞比例明显降低;此外,在两个年龄组小鼠,接种rBCG者脾细胞均产生了较BCG组更高水平的IFNγ;同时,用rBCG免疫的两组小鼠脾脏CD4+IFN-γ+的细胞比例也明显高于BCG免疫各组。结论:无论rBCG还是BCG通过腹腔注射免疫,均可诱导不同年龄BALB/c小鼠产生Th1免疫应答;表达在rBCG细胞壁上的Derp2被当成BCG的成分,为机体免疫系统所识别,抗原再次接触进一步刺激了Derp2特异性的Th1应答。这些结果表明,胞壁型抗原重组BCG可作为有效的疫苗,特异性地调节Th1/Th2平衡。

AIM: To investigate the effects of rBCG vaccination containing foreign antigen Der p2 in the form of lipoprotein on murine immune!response. METHODS: 6 to 8 weeks old and newborn BALB/c mice were vaccined intraperitoneally with 10~6CFU rBCG or BCG. At the same time, the control group was injected with saline. Six weeks later, all animals were injected with Der p2 (20 μg). After two weeks later, the concentrations of IL-4 and IFN-γ in the serum and splenocyte culture supernatant (STLCS) were determined by ELISA, and Th subgroups were determined by double flourescent staining and flow cytometry. RESULTS: After vaccination, the serum and STLCS from both rBCG-immunized and BCG-immunized group of adult and newborn BALB/c mice had significantly higher level of IFN-γ and lower level of IL-4 than those from control groups. Besides, there was the larger percentage of CD4^+ IFN-γ^+ cells in spleen from rBCG-vaccined and BCG-vaccined mice than that from control group. However, the percentage of CD4^+ IL-4^+ cells in spleen cells from rBCG-vaccined and BCG-vaccined group was lower than that from control group. Moreover, the level of IFN-γ in STLCS from rBCG-immunized was significantly higher, compared with that from BCG-immunized mice. At the same time, the percentage of CD4^+ IFN-γ^+ cells in spleen from rBCG-vaccined mice was larger than that from BCG-vaccined group. CONCLUSION: Both rBCG and BCG could stimulate Th1 predominant immune response, when injected intraperitoneally into adult or newborn BALB/c mice; The Der p2 expressed on the cell wall of BCG can work as the component of BCG and be recognized by the immune system of mice, therefore stimulates Der p2-specific Th1 predominant immune response.These data indicate that recombinant BCG-expressing antigens can be used as the antigen-specific vaccines against allergic diseases by regulating the balance of Th1/Th2.