- Organ transplant is successful between individuals having identical major histocompatibility complex (MHC).
- In case of mismatched MHC antigens between individuals, the immune system of the recipient will reject the transplanted organ unless immunosuppressive therapy was performed. Because the recipient will recognize the transplanted organ as non-self and reject it.
- Immunosuppression therapy such as immunosuppressive drugs or irradiation as greatly improved graft survival.
