What is immunosuppression?
If the body’s immune system is suppressed so that it can no longer function properly, this is called immunosuppression. Depending on the extent, the body’s defenses are only weakened or even completely disabled. If you want to understand why immunosuppression can be both undesirable and desirable, you must first understand how the immune system works.
Basics of the immune system
A very targeted fight against pathogens is possible with the specific immune defense. This includes the so-called B lymphocytes – special white blood cells that can produce specific antibodies against a pathogen on first contact with it – matching characteristic proteins (antigens) on the surface of the invader.
Immunosuppression as therapy, side effect or symptom
To treat autoimmune diseases, one intentionally induces immunosuppression in the patient to limit the misdirected behavior of the immune defense. Patients are also given immunosuppressive drugs after transplantation. The aim is to prevent the immune system from attacking and rejecting the foreign organ.
In addition, immunosuppression can be a symptom of various diseases. Two well-known examples are blood cancer (leukemia) and AIDS. While in the case of leukemia the body itself produces defective white blood cells (leukocytes) and thus weakens the immune defenses, in the case of AIDS a pathogen – the HI virus – destroys certain leukocytes. The immune system is also sometimes weakened after major psychological or physical stress.
There are two main areas of application for artificially induced immunosuppression – i.e. immunosuppressive therapy: Autoimmune diseases and organ transplants. In these cases, the immune system is specifically weakened because it would otherwise harm the patient. However, the degree of intervention differs in the two cases.
Immunosuppression after organ transplantation
Although in this case the immune system is only doing its job, if it is not suppressed, this has life-threatening consequences for the patient. Unfortunately, there is therefore no other option after an organ transplant than to carry out lifelong immunosuppression. This means that the patient must permanently take medication that dampens the immune reactions.
Immunosuppression in autoimmune diseases
- Rheumatoid arthritis
- Connective tissue diseases (collagenoses: dermatomyositis/polymyositis, systemic lupus erythematosus)
- Vascular inflammations (vasculitides)
- Chronic inflammatory bowel diseases (Crohn’s disease, ulcerative colitis)
- autoimmune liver inflammation (autoimmune hepatitis)
- pulmonary fibrosis, sarcoidosis
- multiple sclerosis (MS)
- myasthenia gravis
- inflammation of the renal corpuscles (glomerulonephritis) – a form of kidney inflammation
What do you do if you have immunosuppression?
- Induction phase: At the beginning, the physician administers a high dose of medication in order to achieve high concentrations of the active substance in the blood as quickly as possible (induction). Usually, three or four different immunosuppressive drugs are combined for this purpose (triple or quadruple therapy).
Most autoimmune diseases progress in relapses. Particularly strong intervention is required during such an inflammatory episode (induction therapy). In the remission phases, in which the disease is “dormant” to a certain extent, the immune system is usually dampened with significantly lighter agents (maintenance therapy). The aim is to prevent or at least delay a new inflammatory episode.
Drugs for immunosuppression (immunosuppressants)
Calcineurin Inhibitor
Calcineurin is an enzyme that occurs in various body cells, including certain cells of the immune system. There it is important for signal transduction. Calcineurin inhibitors prevent this signal transmission and thus the activation of the immune system. Calcineurin inhibitors that are particularly commonly used for immunosuppression are ciclosporin and tacrolimus.
Cell division inhibitors
Depending on the target, cell division inhibitors are divided into cytostatics (such as azathioprine, mycophenolic acid = MPA and mycophenolate mofetil = MMF) and mTOR inhibitors (such as everolimus and sirolimus).
Antibodies
Artificially produced antibodies are also used for immunosuppression (e.g. infliximab, adalimumab, rituximab). These belong to the so-called biologicals – these are biotechnologically produced drugs.
Since biologicals inhibit the immune system particularly strongly, they must not be administered in certain situations (e.g. during pregnancy or in the case of an acute or chronic infection).
Glucocorticoids (“cortisone”)
What are the risks of immunosuppression?
Therapeutic immunosuppression is in a way a catch-22 situation. On the one hand, the immune system must be suppressed because otherwise it can cause damage (e.g. after organ transplantation). On the other hand, every human being needs functioning defenses to be able to defend himself against pathogens, for example. In addition, the drugs used have a wide range of side effects.
Increased susceptibility to infections and tumors
Patients with long-term immunosuppression also have an increased risk of developing cancer. Because the weakened immune system no longer adequately recognizes and destroys degenerate cells, malignant neoplasms develop more frequently than in healthy people. Those affected should therefore be regularly examined for certain tumors (tumor screening).
Toxic effect on tissue (toxicity)
Damage to the bone marrow (myelosuppression).
The bone marrow is also often attacked by immunosuppression. As a result, the formation of blood cells (red and white blood cells as well as platelets) is disturbed. Possible consequences are increased susceptibility to infections, anemia and increased bleeding tendency.
Increase in fat and sugar levels in the blood
Another side effect of many immunosuppressants (especially steroids) is increased blood sugar levels. Diabetes mellitus may even develop, which the physician must regularly monitor and treat.
Osteoporosis and high blood pressure
Gastrointestinal problems
Some immunosuppressants are poorly tolerated by the gastrointestinal tract. For example, mycophenolate mofetil or azathioprine can cause nausea, vomiting, or diarrhea immediately after taking them. These side effects can have a significant impact on an individual’s quality of life. If such problems occur as a result of taking immunosuppressants, you should talk to your treating physician.
What do I need to be aware of when taking immunosuppressants?
Immediately after a transplant, immunosuppressants are administered in high doses. During this time, the immune system is very vulnerable, so contact with germs must be prevented as far as possible. Patients with a fresh transplant are therefore isolated and wear a mouth guard. Visitors must be healthy, even a small cold can be a danger for the transplanted person.
Seek immediate medical attention if the following warning signs occur shortly after an organ transplant:
- Fever or other signs of infection (weakness, fatigue, cough, burning sensation when urinating)
- pain in the area of the transplanted organ
- decreased or increased urine output
- Weight gain
- diarrhea or bloody stools
