Rejection and Infection

Rejection

The human body has a built in defence mechanism called the immune system.  The  immune system helps the body to destroy germs, such as bacteria and viruses, and helps to fight others diseases such as cancer.  Unfortunately, the immune system views the transplanted organs the same way as harmful diseases, and attempts to destroy the organ as a foreign substance.  Rejection occurs when the transplanted organ is attacked by the immune system.  Without detection and intervention, the transplanted organ will be damaged and subsequently destroyed. 

Following your transplant, you will be given three drugs to suppress the immune system to prevent you from rejecting your new organ.  This will also make you more prone to infection so particular care is taken to prevent and treat infection.

Rejection is a common occurrence and it is anticipated that in a majority of patients, at least one rejection episode will occur.  This will be treated by either increasing your doses of immunosuppressive drugs or using additional drugs.  You should reduce your exercise level for a short time while you are being treated for rejection.

Types of Rejection

A. Hyperacute Rejection

This type of rejection occurs rarely.  It is an immediate rejection that happens within the first several hours after transplantation. 

B. Acute Rejection

Acute rejection usually does not occur for several days after transplantation.  Acute rejection does not occur immediately, because it takes time for the recipient's lymphocytes to realise that the transplanted organ is foreign, in order mount a defence against it. Drugs called immunosuppressives help to overcome acute rejection by blocking the immune system's reaction to the transplanted organ.  Without immunosupressive medications, transplanted organs would probably fail within 2 to 4 weeks as a result of acute rejection. 

C. Chronic Rejection

> Coronary Artery Disease  (Heart Transplant)
Coronary Heart Disease, a type of rejection, is sometimes called chronic rejection.  It usually does not occur until several years after transplant.  The coronary arteries develop progressive and diffuse narrowing throughout their entire length.  The diagnosis is made by coronary angiogram or intravaxcular ultrasound.

> Obliterative Bronchiolitis (Lung Transplant)
This is characterised by progressive airway obstruction due to damage of the cells lining the airways.  This is the most serious long term complication of lung transplantation.  It causes severe deterioration of lung function.  Progression of the process may be arrested with increased immunosuppression.

Infection

When the immune system is suppressed to avoid rejection, it leaves the body more susceptible to infection.  During the first few months after transplant, higher doses of immunosuppressive medications are given because the probability of rejection is greatest during this time.  Consequently the transplant recipient is also most susceptible to infection within the first 6 months after transplant.  Infection may be viral, bacterial, fungal or protozoan.

Prevention of Infection

Do not become obsessed by infection, but use common sense every day.  Good hand washing, cleanliness and personal hygiene are the keys to preventing infection.  During the post transplant hospital stage, visitors will be asked to wash their hands thoroughly before visiting.  Visitors who have a cold or other signs of infection should avoid visiting until they are healthier.  After hospital discharge, avoid crowded environments and anyone who has a cold or active infection.  Don't use public transplant for six weeks after your operation and then try to use it at non peak times.  You are encouraged t lead a normal lifestyle, although caution should be exercised in some areas, e.g.

• Fresh fruit and vegetables should be washed thoroughly before eating.

• Don't eat shared finger food (e.g. bowls of nuts or chips) or share eating utensils or cups and glasses.

• Wear gloves when gardening.

• Wash your hands after handling pets, don't let pets sleep on your bed and wear gloves when cleaning bird cages and cat litter.

• Don't use a public swimming pool for 3 months after your operation.

Types of Infection

Bacterial Infections
Bacterial infections are one of the more common types of infection occurring port-transplant.  Most of the organisms inhabit the skin or body cavities.  Generally these organisms do not cause problems in normal individuals, but may lead to infections in the immunosuppressed patient.  Bacterial organisms include staphyloccous, streptococcus, pseudomonas, among others.

Viral Infections
Viruses are the most common cause of infections in transplant patients after the first month.  Examples of viral infections include: CMV (cytomegalovirus), Herpes (simplex or zoster), and Herpes.  During the pre-transplant screening, the recipient is tested for previous exposure to CMV, herpes, hepatitis, and HIV (AIDS virus).  Having active hepatitis or HIV would exclude the patient as a candidate for transplantation, although previous exposure to hepatitis may allow the patient to be considered.

CMV - Cytomegalovirus
CMV is the most common infection following heart or lung transplant.  It accounts for approximately 25% of all infectious episodes.  More than 60% of Australians had previous exposure to CMV which is a benign illness causing only flu-like symptoms.  In the immunosuppressed patient, CMV may cause a more serious illness resulting in hospitalisation.  Manifestations include flu-like illness, pneumonia, hepatitis, gastritis, and in rare cases death.  The symptoms of CMV are similar to those previously listed for infections.  Patients wih CMV exposure and those whose donor had previous CMV exposure are treated prophylactically with a drug called Ganciclovir for the first 2-3 months after transplant in order to prevent CMV infection.

Fungal Infections
Fungal infections may range from very mild (thrush) to life threatening.  Examples of fungal infections include, candida, aspergillosis, and histoplasmosis