Importance of the immune system
In the case of leukemia (white blood cancer), under chemotherapy or in the case of congenital immune system defects, the consequences for the affected patients can be serious in some cases. Affected patients often suffer recurrent and sometimes serious infections, which can also be fatal. This is particularly evident in the case of acquired immunodeficiency syndrome (AIDS), where the T-helper cells 2 are missing in the final stage of the disease, resulting in infections with pathogens that would normally stand no chance against the healthy immune system, e.g. the bacterium Pneumocystis carinii or the parasite Toxoplasma gondii.
In leukemias, there is no adequate formation of immune cells/immune system. This results in equally serious problems for the patient. Chemotherapy not only destroys the malignant cancer cells, but as an undesirable effect it also destroys healthy, fast-dividing cells, including the immune cells of the immune system.
On the other hand, there are a large number of so-called autoimmune diseases in which the immune system mistakenly turns against its own body. Antibodies can form against almost all tissues of the body, e.g. against blood vessels in Churg-Strauss disease, against kidneys in so-called glomerulonephritis, against the thyroid gland in Hashimoto’s thyroiditis, against the spine in ankylosing spondylitis, against colon tissue in ulcerative colitis, against cells of the pancreas in diabetes mellitus type 1, against nerve tissue in multiple sclerosis, etc. The immune system also plays a central role in allergies.
In allergic reactions, the immune system reacts excessively, i.e. too violently, to a certain substance (the so-called allergen). This reaction of the immune system can be life-threatening under certain circumstances, e.g. if it leads to narrowing of the respiratory tract. Allergic diseases such as asthma, neurodermatitis (atopic eczema) or hay fever are caused by such excessive reactions of the immune system.
The immune system therefore has a vital function for the human organism. Defects in the immune system can lead to death. On the other hand, the immune system itself can also be the cause of a disease.