Host versus graft reaction is the rejection reaction that caused by parenchyma organ transplantation, which can be divided into three parts. Namely, hyperacute rejection, acute rejection and chronic rejection reaction according to the time when
the rejection reaction occurs,intensity and pathological change and its mechanism.Acute rejection is the most common rejection reaction after allotransplantation,
which occurs mostly one month later or within three months after transplantation. Cellular immunity is the major one in Acute rejection reaction, Recipient T Cell
recognizes the allotype MHC antigen of APC surface of the donor directly, then activate and reproduce, and brings about detriment to transplants through different
effects and mechanisms. greater omentum wraps the trachea transplant, and trachea of the donor will not build up the blood supply immediately, the
revascularization of trachea transplant will normally complete within one week,and it normally does not produce blood serum, body fluid and cause immune-meditated hyperacute rejection. Therefore, we have programmed to observe the trachea about the histological change of allograft at different time points within three months in order to conduct a research on the acute rejection reaction of the trachea transplant. Finally, it turned out that cryogenic freezing can have an evident decrease on the antigenicity of the trachea transplant.