| Objective:The development of various combinations of immunosuppressive therapy has significantly improved the short-term graft survival rates. However, a constant proportion of organs were lost every year due to chronic allograft rejection and immunosuppressive drug toxicity. The induction of donor-specific tolerance has the potential of at least partially resolving this problem, since it might prevent chronic rejection and drug toxicity at the same time. Astragalus is a kind of Chinese herb, which can up or down-regulate the immune system under various conditions while has slight side effects. On the basis of past studies, it's supposed that Astragalus may play an important role in inhibiting rejection response and inducing allogeneic transplantation tolerance.An important mechanism that maintains allogenic antigen specific immune tolerance functions through suppressive regulatory T cells. Recently, the forkhead/winged helix transcription factor (Foxp3) was found to be unique expressed by CD4~+CD25~+ T cells. And it is thought to act as a master switch controlling CD4~+CD25~+ T cells differentiation. As a kind of regulatory T cells subset, CD4~+CD25~+ T cells are known to suppress effector T cell proliferation through a cell contact-dependent mechanism that is largely cytokines independent; on the other hand , blockade of both EL-10 and TGF-β has been reported to abrogate CD4~+CD25~+ T cells -mediated unresponsiveness to alloantigen. Our Experiments investigate the impact of high dose Astragalus on the survival period of the allograft,...
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