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.
- 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).
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.
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.