| Subject | Contents |
| Definition | A consequence of organ or tissue transplantation caused by the transplant recipient's (host's) immune response to the transplanted organ/tissue which can damage or destroy it. See also graft-versus-host disease. |
| Alternative Names | Graft rejection; Tissue/organ rejection |
| Causes, incidence, and risk factors | The immune response protects the body from potentially harmful substances (antigens) such as microorganisms, toxins , and cancer cells. The immune system distinguishes "self" from "foreign" by reacting to proteins on the surfaces of cells. It reacts against substances it recognizes as foreign (antigens). The presence of foreign blood or tissue in the body triggers an immune response that can result in blood transfusion reactions and transplant rejection when antibodies are formed against foreign antigens on the transplanted or transfused material. Before transplant, tissue is "typed" according to the antigens it contains ( Histocompatibility antigens ).
No two people (except identical twins) have identical tissue antigens. Therefore, in the absence of immunosuppressive drugs, organ and tissue transplantation would almost always causes an immune response against the foreign tissue (rejection), which would result in destruction of the transplant. Though tissue typing ensures that the organ or tissue is as similar as possible to the tissues of the recipient, unless the donor is an identical twin, no match is perfect and the possibility of organ/tissue rejection remains. Immunosuppressive therapy is used to prevent organ rejection.
There are some exceptions, however. Corneal transplants are rarely rejected because they have no blood supply, so lymphocytes and antibodies do not reach the cornea to cause rejection. And, as mentioned above, identical twins have identical tissue antigens, so transplants from one twin to another are almost never rejected.
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| Symptoms | reduced organ function rarely, pain or swelling in the location of the organ rarely, fever general discomfort, uneasiness, or ill feeling ( malaise ) Note: Symptoms vary with the specific organ or tissue. Patients who are rejecting a kidney may see decreased urine output. In the case of rejecting a transplanted heart, there may be symptoms of heart failure. |
| Signs and tests | There may be tenderness on palpation over the organ (particularly the kidneys). Signs of reduced organ function are often present such as decreased urine output with kidneys, symptoms of liver failure like yellow skin color and easy bleeding with liver transplants, or symptoms of heart failure, such as shortness of breath and decreased exertional tolerance for hearts. A biopsy of transplanted organs confirms rejection. Routine biopsy is often performed to detect rejection early, before symptoms develop. Tests that may be performed prior to an organ biopsy in a patient suspected of having organ rejection include: lab tests of renal or liver function renal ultrasound renal arteriography abdominal CT scan cardiac echo chest X-ray |
| Treatment | The goal of treatment is to maintain the integrity and functioning of the transplanted organ or tissue while suppressing the host's immune response.
Suppression of the immune response is used for both treatment and prevention of transplant rejection. Corticosteroids such as prednisone are used to reduce the immune response. The dosage may be very high during treatment of acute rejection episodes and then reduced to a lower "maintenance" dose to prevent recurrence. Immunosuppressant medications include azathioprine and cyclosporine. OKT2 monoclonal antibodies can be used as well because they specifically reduce the activity of T lymphocytes, which are the primary immune system cells responsible for transplant rejection.
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| Expectations (prognosis) | The outcome varies. Some organs and tissues are more successfully transplanted than others. Rejection may be reversed with treatment or may progress despite treatment. Immunosuppression must continue for the rest of the person's life. |
| Complications | loss of function of the transplanted organ/tissue infection resulting from chronic immunosuppression side effects of medications, may be severe (see the specific medication) |
| Calling your health care provider | Call your health care provider if transplanted organ or tissue shows reduced function, or other symptoms of transplant rejection occur. Also, call your health care provider if medication side effects develop. |
| Prevention | ABO (blood group) and HLA (tissue antigen ) typing before transplantation ensures a close antigenic match. Suppression of the immune system is usually necessary for the rest of the transplant recipient's life to prevent rejection. |
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