| Objective This study was designed to investigate the effect of CD4+CD25+ regulatory T cells on the recipient immunoloregulation in the model of SD to Wistar rat cardiac allotransplantation. The mechanisms of rejection in allotransplantation will be explored in the model.Materials and methods 5 x 107 allogeneic apleen cells of SD rats were inoculated into thymuses gland of Wistar rats. After inoculation, we observed the quantity change of rat CD4+CD25+ regulatory T cells at different time.CD4+CD25+ regulatory T cells were isolated from Wistar rat splenocytes and peripheral lymph nodes by using magnetic cell sorting system (negative selection and positive selection). The purity of isolated CD4+CD25+ regulatory T cells was detected by flow cytometry.Donor(SD rat) and recipient (Wistar rat) were divided randomly into four groups. Group A(no treatment): The heart from SD rat was transplanted into the abdomen of Wistar rat without any pre-treatment; Group B(conventional measure): Tolerance was induced in Wistar rats by the administration of 1 mL ALS intraperitoneally 1 day before heterotopic transplantation and 5 x 107 SD rat splenocytes intrathymically 21 days before transplantation using a SD donor; Group C (control group): 1x 106 fresh CD4+CD25+ regulatory T cells were injected intravenously into the penile vein of each Wistar rat 1 day before transplantation; Group D (experimental group): the recipients were injected with 1x 106 CD4+CD25+ regulatory T cells isolated from the tolerated rats of group B 1 day before transplantation. The mean survival time (MST) of grafted heart, the optical density(OD) of mixed lymphocyte reaction (MLR), the expression of IL-2,TGF-β1 and the pathology were observed.Results (1)The quantity of Wistar rat blood CD4+CD25+ T regulatory cells increased obviously as early as 1 wk and the levels reached the top after intrathymic inoculation at 1 wk and the levels returned to normal at 3 wk. (2)MST: Group A: 6.8±1.9d; Group B: 73.2±7.7d; Group C: 47.4±13.3d; Group D: 79.6±7.9d. The MST of Group B> GroupD, but P >0.05. Group B,Group C and group D were longer than group A, P<0.05. The MST of Group D > Group C, and P<0.05. (3)The results of MLR: No pretreatment group(A): 1.00±0.10; Conventional group(B): 0.67±0.05;Control group(C): 0.77±0.06; Experimental group(D): 0.66±0.07. The optical density (OD) of conventional and experimental group was much lower than no pretreatment group, P<0.05. There was no fifference in MLR between conventional group and experimental group , P>0.05 . (4)The expression of IL-2: The level of IL-2 was higher when the grafts rejected than that before transplantation in no treatment group, P<0.05. In experimental group, expression of IL-2 was not greater than those in na?ve Wistar rats , P >0.05 . IL-2 after grafting in experimental group is lower than that in control group, P<0.05. (5)The expression of TGF-β1: The TGF-β1 level of no treatment group was not higher when the grafts rejected than that before transplantation , P >0.05 . In experimental group, TGF-β1 was strongly expressed on day 7,25 and 50 after grafting, P<0.05. TGF-β1 after grafting in experimental group is higher than those in control group, P<0.05.Conclusions 1,The IT rat can generate CD4+CD25+ T regulatory cells which can regulate the recipient T cells.2,Infusing CD4+CD25+ regulatory T cells can precipitate Th1 and Th2 cell respondence to immune deviation . Secretion of IL-2 is inhibited, while expression of TGF-β1 is increased. It helps to induce immune tolerance .3,Infusing CD4+CD25+ regulatory T cells isolated from the tolerated recipients can carry out the transfer of immune tolerance. CD4+CD25+ regulatory T cells isolated from the tolerated recipients are superior to freshly isolated CD4+CD25+ regulatory T cells. |
PDF Full Text Request