Rejection reaction


If our body’s own immune system recognizes foreign cells, it activates various mechanisms to protect against the mostly undesired invaders. Such a reaction is intentional if pathogens such as bacteria, viruses or fungi are involved. However, a rejection reaction is not desired in the case of organ transplantation.

In the worst case, the foreign cells are destroyed and the transplanted organ loses its function. However, rejection can be prevented. To do this, the natural reaction of the body’s own defence system is suppressed with the help of medication – this is called immunosuppression.

The corresponding drugs are called immunosuppressive drugs. A distinction is made between hyperacute, acute and chronic rejection reactions. A hyperacute reaction takes place just a few minutes to hours after the operation.

The acute rejection reaction refers to the immune reaction in the first days and weeks after the transplantation. Thanks to regular check-ups, this can usually be treated well. The chronic reaction, on the other hand, takes place more slowly and only leads to permanent damage to the organ in the course of the operation. The acute reaction is often accompanied by typical symptoms, while the chronic rejection can remain clinically unremarkable for a long time.


In order to diagnose a possible rejection reaction in time, it is important that certain values are checked regularly at short intervals. These include blood pressure, temperature, body weight, the amount of fluid supplied and the amount of urine excreted. Furthermore, the drug therapy should be checked.

In this way one tries to recognize possible immune reactions in time or to prevent them. If a rejection reaction is suspected, additional examinations are carried out. In addition to the physical examination, the laboratory parameters and the urine with urine stix, urine sediment and urine culture are examined.

In addition, apparatus-based examination methods are used. These include an ultrasound of the transplanted organ and, if necessary, an X-ray or magnetic resonance tomography. Furthermore, a biopsy, a tissue removal by needle, is often performed to histologically secure the rejection reaction.


Acute rejection is treated with immunosuppressive drugs and can be treated well if detected early. As a rule, high-dose cortisone is administered for a period of three days. Furthermore, the already existing immunosuppression is increased and individually supplemented with another drug to suppress the immune defence.

If the rejection reaction proves to be resistant to cortisone, special antibodies against T cells are used. This form of therapy should not be maintained for longer than 3 to 10 days. Adequate dosage plays an important role in a chronic rejection reaction.

On the one hand, the immunosuppressive drug should be dosed at such a high level that the cells of the transplanted organ are not destroyed; on the other hand, the body’s own defence system must not be completely suppressed. A simple cold could have far-reaching consequences if the immune system is not functioning. Immediately after the procedure, a higher dosage is necessary to prevent the subacute and acute rejection reaction.

During this time the immune system is particularly weakened and susceptible to infection with bacteria, viruses or fungi. Strict hygiene measures should be observed here. In general, immunosuppressive therapy must last a lifetime.