Aim: To study the effect of Rapamycin(Rapa) on CD4(+) CD25(+) regulatory T cells in allo-transplantation tolerance model.
Methods: The model of skin allo-transplantation was established. The recipient BALB/c mice were injected with allogeneic donor spleen cells from B6 on the day before grafting and with cyclosporine(CsA) after transplantation. T cells were purified on the day 14 from the tolerant group and cultured with Rapa and/or IL-2 in different concentrations in vitro. Mixed lymphocyte reaction (MLR) was used to analyze the specific recall reaction of T cells. Percentages of CD4(+) CD25(+) regulatory T cells were examined by flow cytometry (FCM). The expression of Foxp3 mRNA was measured by RT-PCR, and the level of IL-10 in supernatant of T cells cultured in vitro was determined by ELISA. BALB/c-SCID mice underwent allo-transplantation were given adoptive transfer of T cells treated with Rapa and/or IL-2, then the survival conditions of the grafted skin were observed daily.
Results: CsA plus donor splenocyte injection can prolong allograft of BALB/c significantly (P<0.05). The number of CD4(+) CD25(+) regulatory T cells and the expression of Foxp3 mRNA for T cell in the tolerant group treated with Rapa and/or IL-2 were obviously increased. Adoptive transfusion of T cells from tolerant mice treated with IL-2/Rapa obviously prolonged the allograft survival time in allografted-SCID mice.
Conclusion: Rapa can increase the ratio of CD4(+) CD25(+) regulatory T cells in vitro and prolong the graft survival time obviously after adoptive immunity, and these effects are enhanced by low-dose of IL-2.