Transplant Rejection
Transplant Rejection
The immune system of our body is much like the defense system of a nation. Specialized cells [e.g. T-cells] and proteins [human leukocyte antigens (HLA)] in the blood destroy the organisms/toxins invading our body. They have the natural ability to determine when other bacteria or agents are invading our body and efficiently kill these invaders. So, when we develop an infection, our immune system quickly develops the ability to kill these organisms and the infection resolves. Further, the immune system also takes care that the same organism does not attack the body again.
Now, when a transplanted organ is introduced in the body, the immune system assumes it to be the 'invading organism' and begins to attack and kill the tissues of the introduced organ. This is known as the transplant rejection - when the body rejects the organ transplanted.
An important exception to the transplant rejection is the corneal transplant. These transplants are rarely rejected as corneas have no blood supply. Again, transplants involving identical twins also do not show rejection.
Types of rejection: Transplant rejection can occur in three ways:
- Hyperacute rejection occurs when a blockage or clot is formed in a blood vessel or there is a hemorrhage of the transplanted organ's blood vessels. This type of rejection occurs within 24 hours after transplantation.
- Acute rejection occurs because of mismatched HLA that are present in cells. It usually begins after 7 days of transplantation.
- Chronic rejection is characterized by arterial occlusions (obstruction in arteries) associated with fibrosis. It may occur after several months following a transplant.
Signs and symptoms: Symptoms vary from one person to person and also depends on the transplanted organ or tissue. In general, following are the symptoms of rejection:
- The organ does not function properly. For example, shortness of breath, chest congestion and pain or tenderness around the lung in case of lung transplant; yellow skin color and bleeding with liver transplants; less urine production in kidney transplant.
- General discomfort and uneasiness.
- Fever over 100 degree F (38 degree C).
- Fatigue.
Call your health care provider if you feel your transplanted organ is not functioning properly or if you develop side effects with the medication.
Identifying the rejection: A biopsy of the transplanted organ can confirm if the body is rejecting the transplantation. But, before a biopsy is done, the following tests are usually recommended:
- Repeated blood work, including a complete blood count.
- CT scan and chest x-ray
- Bronchoscopy in case of lung transplant; echocardiography in case of heart transplant; lab tests to check kidney or liver function, ultrasound and arteriography in case of liver and kidney transplants.
Treatment: Says Dr. Mark Benfield, director of the Division of Pediatric Nephrology & Transplantation at the University of Alabama at Birmingham, 'The ultimate goal of all transplantation is to induce transplantation tolerance. This is the ability to manipulate the immune system in a way to confuse it into thinking that the transplanted organ is part of "self" so that no immune response is mounted, no medications are needed and no rejection occurs'.
In other words, he means that transplant rejection can be treated and prevented by suppressing the immune response. Many different drugs are used these days to suppress the immune response. These are discussed in the next page.
References:
- Transplant rejection - (http://www.nlm.nih.gov/medlineplus/ency/article/000815.htm)
- An Update on Immunosuppressive Medications in Transplantation - (http://www.fmshk.org/database/articles/897.pdf)
- Immunosuppressive drugs - Snell GI, et al. Everolimus versus azathioprine in maintenance lung transplant recipients: an international, randomized, double-blind clinical trial. Am J Transplant 2006; 6:169.
- Immunosuppressive drugs - Kawai, Tatsuo et al. HLA-Mismatched Renal Transplantation without Maintenance Immunosuppression. N Engl J Med 2008 358: 362-368. Volume 358:362-368, January 24, 2008, Number 4.
- Immunosuppressive drugs - E K Geissler and H J Schlitt. Immunosuppression for liver transplantation. Gut 2009; 58; 452-463; originally published online 3 Dec 2008;
- Informed Consent in Living Organ Donors - (http://www.biology-online.org/articles/informed_consent_living_organ.html)
- Recovery of transplantable organs after cardiac or circulatory death: Transforming the paradigm for the ethics of organ donation - (http://www.peh-med.com/content/2/1/8)
- Presumed Consent or Mandated Choice to Overcome Organ Shortage - (http://www.mohanfoundation.org/organ-donation-transplant-resources/presumed-consent-mandated-choice-overcome-organ-shortage.asp)
- Chouhan P and H Draper. Modified Mandated Choice for Organ Procurement J Med Ethics. 2003;29(3):157-162, at p. 158.
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