Rejection and others. Several including rejection of the graft. Some recipients can also have a recurrence of the disease that caused the kidneys to fail, or develop de novo (new) auto immune kidney diseases. In addition, the immunosuppressive drugs taken to prevent rejection may also predispose the recipient to infections and cancers at a higher rate than the untreated population.
Sensitization. Patients can become sensitized to other antigens while on dualisms, especially if they receive blood transfusions.
Kidney transplant. Most important is that there is compatibility between donor and recipient.