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Transplant rejection


Transplant rejection is a process in which a transplant recipient's immune system attacks the transplanted organ or tissue. See also: Graft-versus-host disease

Alternative Names

Graft rejection; Tissue/organ rejection

Causes, incidence, and risk factors

Your body's immune system usually protects you from substances that may be harmful, such as germs, poisons, and cancer cells.

These harmful substances have proteins called antigens on their surfaces. As soon as these antigens enter the body, the immune system recognizes them as foreign and attacks them.

In the same way, an organ that is not matched can trigger a blood transfusion reaction or transplant rejection. To help prevent this reaction, doctors "type" both the organ donor and the person who is receiving the organ. The more similar the antigens are between the donor and recipient, the less likely that the organ will be rejected.

Tissue typing ensures that the organ or tissue is as similar as possible to the tissues of the recipient, but the match is usually not perfect. No two people (except identical twins) have identical tissue antigens.

Doctors use a variety of drugs to suppress the immune system and prevent it from attacking the newly transplanted organ when the organ is not closely matched. If these drugs are not used, the body will almost always launch an immune response and destroy the foreign tissue.

There are some exceptions, however. Cornea transplants are rarely rejected because the cornea has no blood supply. Immune cells and antibodies are not able to reach the cornea to cause rejection. In addition, transplants from one identical twin to another are almost never rejected.

There are three types of rejection:

  • Hyperacute rejection occurs a few minutes after the transplant, if the antigens are completely unmatched. The tissue must be removed right away so the recipient does not die. This type of rejection is seen when a recipient is given the wrong type of blood.
  • Acute rejection may occur any time from the first week after the transplant to 3 months afterward. Everyone has some amount of acute rejection.
  • Chronic rejection takes place over many years. The body's constant immune response against the new organ slowly damages the transplanted tissues or organ.


  • The organ's function may start to decrease
  • General discomfort, uneasiness, or ill feeling
  • Fever (rare)


Signs and tests

The doctor will examine the area over and around the transplanted organ, which may feel tender to you (especially with a kidney transplant).

There are often signs that the organ isn't working properly, such as:

  • High blood sugar (pancreas transplant)
  • Less urine released (kidney transplant)
  • Yellow skin color and easy bleeding (liver transplant)




The goal of treatment is to make sure the transplanted organ or tissue works properly, and to suppress your immune system response. Suppressing the immune response can prevent transplant rejection.

Many different drugs can be used to suppress the immune response. The medication dose depends on your condition. The dose may be very high while the tissue is being rejected. Then the dose may be lowered to prevent rejection from happening again.

Expectations (prognosis)

Some organ and tissue transplants are more successful than others. If rejection begins, drugs that suppress the immune system may stop the rejection. Most people need to take these drugs for the rest of their life.

Even though potent drugs are used to suppress the immune system, organ transplants can still fail because of rejection.




  • Certain cancers (in some people who take strong immune suppressing drugs for a long time)
  • Infections (because the person's immune system is suppressed)
  • Loss of function in the transplanted organ/tissue
  • Side effects of medications, which may be severe

Calling your health care provider

Call your health care provider if the transplanted organ or tissue does not seem to be working properly or if other symptoms occur. Also, call your health care provider if medication side effects develop.


ABO blood typing and HLA (tissue antigen) typing before a transplant helps to ensure a close match. You will usually need to take medicine to suppress your immune system for the rest of your life to prevent the tissue from being rejected.

Being careful about taking your post-transplant medications, and being closely watched by your doctor may help prevent rejection.


Eghtesad B, Miller CM, Fung JJ. Liver transplantation management. In: Carey WD, ed. Cleveland Clinic: Current Clinical Medicine. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2010.


Review Date: 6/14/2011
©  2014 


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