Donor Specific Transfusion Combined With Dexamethasone Treatment Induced Long-term Survival Of Skin Grafts In Mice

Objective: To investigate whether donor specific transfusion with rapamycin can induce long-term engraftment and relative mechanism.Methods: 1. In vivo,evaluate the role of dexamethasone combined with DST in skin transplant models in mice. The recipients (C57BL/6 mice) were randomly divided into two groups (n=6 each) and skin transplantations were performed taking the Balb/c mice as donors. Experimental group: C57BL/6(H-2b) pretreated with Donor specific transfusion (On day 0) combined with dexamethasone (from day 1 to 7, 10 mg/kg/day). On day 8, the transplantations described previously were performed. Control group: The recipients underwent the transplantation without dexamethasone given. The mean survival time and the histopathology representation of the grafts, the apoptosis cell ratio, the CD4+CD25+regulatory T cell ratio, alloreactive T cell activation and generation ability were recorded and detected before the transplantation and seven days after the tranlplantation. 2. In vitro, experimental group: The Splenocyte of the recipient mice in the experimental group in vivo and the splenocyte of the Balb/c(H-2d) blocked by mitomycin were harvested for one-way MLC. Control group: The splenocyte of the normal C57BL/6 untreated is responding cells. The proliferation of cultured cells were detected.Results: In vitro,the activation and generation ability of alloreactive T cells decreased obviously (P <0.05). In vivo,The mean survival time of the skin grafts in experiment group is 19.27±1.68 days which is significantly shorter than that of control group (MST=11.56±1.19 days) (P <0.05) and the ratio of apoptosis cell and the CD4+CD25+ regulatory T cell ratio increased (P <0.05) comparing with that in the control group before the tranlplantation and seven days after the tranlplantation.The histopathology of skin grafts show the rejection of the experimental group are obviously milder than the control group appearancely.Conclusions: Our study suggested that donor specific antigen transfusion combination with dexamethasone can remarkably prolong skin allograft survival. This result may be associated with the increase of the apoptosis of antigen-specific T cell and the ratio of the CD4+CD25+ regulatory T cell together with a state of specific engraftment of alloantigen or tolerance.