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Thursday, April 24, 2014
The immune system is the body's defense system. It attacks foreign invaders to protect the body from outside organisms. The immune system recognizes the transplanted organ as a harmful threat and attempts to destroy it. This attack by the immune system is what causes organ rejection. Without detection and intervention, the transplanted organ will eventually be destroyed.
The Symptoms of rejection and infection can be similar. To determine the cause of certain symptoms, a transbronchial biopsy may be necessary.
Hyperacute Rejection - Hyperacute rejection rarely occurs, but it happens when the body has been exposed previously to the same or similar antigens found in the donor organ. Previous exposure to these antigens may have resulted from blood transfusion, pregnancy, or previous organ transplants. The body's immune system remembers the prior exposure and triggers an instantaneous response that could lead to organ failure within a few hours.
Acute Rejection - Acute rejection usually does not occur until several days after transplant. The anti-rejection drugs (immunosuppressant drugs) help prevent rejection by blocking the immune system. However, many transplant recipients experience 1 or more of rejection within the first year following lung transplantation. Increasing understanding about rejection in the lung now identifies at least 2 different ways that acute rejection may occur. One has been understood for a long time, is more common and is generally known as cellular rejection. In this type of acute rejection immune cells known as lyphocytes accumulate in the lung and cause dysfunction. Another way that rejection now appears to occur is by the production of antibodies against the transplanted lung. This is known as humoral rejection. Treatment and identification of each of these forms is somewhat different.
Chronic Rejection - Chronic rejection (or obliterative bronchiolitis) occurs months to years after transplant. It is characterized by scarring and fibrosis of the small airways and a chronic deterioration in lung function. It may be the result of repeated episodes of acute rejection and/or infection.
A combination of drugs is used to prevent rejection; each drug works in a different way. The combination is called maintenance therapy and will be taken indefinitely. Anti-rejection drugs are explained in greater detail in the NetWellness feature Medications to Treat Lung Transplant.
When acute rejection is detected, additional drug therapy will be needed. Biopsy results and the patient's condition determine the type of drug required to fight rejection. Some of the drugs used will require hospitalization for them to be properly administered. Drug treatment of an episode of acute cellular rejection is usually successful. As noted above, humoral rejection may also occur and is treated by a combination of medications, immunoglobulins or other products or procedures which attempt to decrease antibody production against the transplanted lung or remove antibody from the blood.
Chronic rejection is treated is much more difficult to treatment and typically does not respond to simple increase in the level of conventional immunosuppression.
It is common for patients to experience episodes of acute rejection particularly during the first year.
Preventive testing - Evidence of rejection may be present in cells before symptoms can appear. Because symptoms can be subtle, surveillance bronchoscopies are done at regular intervals along with biopsies and cultures of the transplanted lung to rule out infections.
Take medications as prescribed - Never stop or change the immunosuppressive medications without consulting the transplant coordinator or transplant pulmonologist.
Don't take new medications until you talk to your doctor or transplant coordinator - Always call the transplant coordinator before taking any new medications other than those prescribed by the transplant team. Some medications interfere with immunosuppressive medications.
This information originally appeared in the University Hospitals Lung Transplantation Patient Handbook, and was adapted for use on NetWellness with permission, 2007.
Last Reviewed: Aug 27, 2013
Robert Schilz, DO, PhD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University