霉酚酸酯对树突状细胞抗原递呈功能的影响和诱导同种移植免疫耐受作用

目的观察霉酚酸酯对体外培养的树突状细胞(DC)前体(DCp)的成熟过程和同种免疫刺激活性的影响作用,评价预先用霉酚酸酯处理的供者DC在诱导同种移植物受者免疫耐受中的作用,并阐述可能的机制。方法(1)在骨髓来源的DCp培养过程中加入粒细胞巨噬细胞集落刺激因子(GM CSF)和霉酚酸酯,用流式细胞术方法进行免疫表型分析,ELISA方法检测其白细胞介素(IL)12的分泌,并作混合淋巴细胞反应以观察其对同种T细胞的刺激能力。(2)24只C57/BL6小鼠被随机分成3组,每组8只,A组C57/BL6受者接受BalB/c小鼠供者心脏进行异位移植,B组C57/BL6受者在移植前7d注射未经处理的BalB/c供者DCp后进行异位移植,C组C57/BL6受者在移植前7d注射经霉酚酸酯处理的BalB/c供者DCp后进行异位移植,观察受鼠移植心脏的存活时间以及血清中细胞因子的变化。结果霉酚酸酯显著抑制了外源刺激下DCp的成熟过程,抑制其表面共刺激分子(CD80、CD86)的表达,降低IL12的分泌并显著抑制其同种T细胞激活能力(P<0.01)。接受未成熟DCp回输的受者移植心脏组(组B、组C)存活期显著长于单纯移植组(组A),而以霉酚酸酯处理的未成熟DCp(组C)可使移植物的存活时间得到进一步的延长,并且显著抑制了TH1细胞因子的产生。结论霉酚酸酯对DCp的成熟和功能有着显著的抑制作用,并能

The influence of mycophenolate mofetil upon the maturation and allostimulatory activity of cultured dendritic cell progenitors and the effects of tolerance induction in allograft recipients

OBJECTIVE: To investigate the influence of mycophenolate mofetil (MMF) on the maturation and allostimulatory activity of cultured dendritic cell progenitors (DCPs) and to evaluate the efficacy of pretreatment of donor dendritic cells (DCs) with MMF in tolerance induction in allograft recipients and its possible mechanism. METHODS: DCPs of Balb/c mice were cultured in culture fluid containing recombinant mouse granulocyte-macrophage colony stimulating factor (GM-CSF), and then divided into 4 groups: control group, MMF group, lipopolysaccharide (LPS) group, and MMF + LPS group. Seven days later, flow cytometry was used to analyze the phenotypes of the DCs. ELISA was used to examine the level of IL-12 in the supernatant. T cells from the spleens of C57/BL6 mice were cultured together with inactivated DCs from Balb/c mice, and added with [(3)H]-TdR. Mixed lymphocyte reaction (MLR) was analyzed. The DCs and MMF-DCs cultured for 5 days were co-cultured with T hybridoma cells of the line MF2.2D9 in culture fluid containing ovalbumin (OVA). Twenty-four hours later, the supernatant was collected and ELISA was used to measure the level of interleukin (IL)-12 so as to reflect the antigen-presenting ability of the DCs. OVA immunized C57/BL6 mice for 4 times. 21 days after T cells were collected from the spleens and co-incubated with DCs and MMF-DCs, [(3)H]-TdR was added and the values of counts per minute (cpm) were calculated so as to analyze the antigen-specific proliferation. Twenty-four Balb/c mice were randomly divided into 3 groups: group A (without treatment), group B (treatment with intravenous injection of untreated DCs of Balb/c mice), and group C (treatment with intravenous injection of DCs of Balb/c mice treated with MMF), and then transplanted with the hearts of C57/BL6 mice. The functions of the transplanted hearts were evaluated by touching the arterial pulse and histological examination. ELISA was used to detect the levels of Th1 cytokines, such as IL-12, IL-4, IL-10, IL-2, and IFN-gamma, in the cultured DCs and in the sera of the recipients 7 and 14 days after culture or transplantation. RESULTS: The immunophenotypic analysis showed that in comparison with those in the control group and the LPS group the expressions of the costimulatory molecules, Ia(d), CD80, and CD86, of the DCPs were significantly weaker in the MMF-group and MMP + LPS group. The IL-12 levels in the supernatant of the MMF and MMF + LPS groups of DCPs were significantly lower than those in the other groups (P < 0.01). The IL-12 level of the MF2.2D9 cells treated with MMF-treated DCs was significantly lower than control group (P < 0.01). The ability to stimulate proliferation of T cells of the same genotype in the MMF-DC group was significantly inhibited (P < 0.01). The survival time of the transplanted heart was 30.50 +/- 3.25 days in the C57/BL6 mice injected with untreated DCPs of Balb/c mice (21.25 +/- 2.12, P < 0.01) and that in the control C57/BL6 mice (8.63 +/- 1.06 days, P < 0.01) and with a significant difference between the latter 2 groups too (P < 0.01). The levels of, such as IL-2 and IFN-gamma, 7 and 14 days after heart transplantation of the group B were all significantly lower than those of the group A (both P < 0.05). The IL-2 and IFN-gamma levels 7 days after the heart transplantation were similar to those in the group B (both P > 0.05) and even lower than those of the group C (both P < 0.05). The IL-10 level in the groups B and C were all higher than those in the group A (all P < 0.05) with a significant difference between the group B and group C. The level of IL-4 was not significantly different among the 3 groups. CONCLUSION: MMF has a significant suppressive effect on the maturation and function of DCs, which leads to a donor-specific tolerance in transplant recipients.