Our immune system is a highly complex system that can cope with a wide range of different threats to health. These include not only pathogens such as viruses and bacteria, but also, for example, altered endogenous cells.
To be able to perform all these tasks, the immune system has a whole arsenal of different and very effective weapons at its disposal. This is why we are unaware of most attacks.
Even the skin and mucous membranes form an insurmountable hurdle for most invaders. If this barrier is attacked, we are immediately much more susceptible to infections. This is why disinfection and care of even small skin lesions is so important.
If an intruder manages to overcome this hurdle, he can by no means make himself comfortable. Within a very short time, the innate immune system begins to fight the unknown. Enzymes and small peptide molecules try to eat up the outer layer of a bacterium, for example. Other proteins attach themselves to the surface and try to tear entire holes in it.
The next line of defense is macrophages, which are scavenger cells. As the name makes clear, macrophages eat the invader and thus render it harmless. At the same time, macrophages release signaling substances that initiate an inflammatory response.
Often, eliminating the intruder does not work without further ado. Then another step is added: B lymphocytes are used. They are formed in the bone marrow. They collect in the lymph nodes and the spleen. There they form antibodies against the invaders (= antigens).
The T lymphocytes mature in the thymus. T lymphocytes are capable of destroying whole cells or parasites. Together with the B-lymphocytes, the T-lymphocytes form the specific immune defense, which is able to specifically recognize and destroy, for example, a bacterium or virus. The great advantage of the specific immune defense is the ability to remember these invaders and to react quickly to them the next time.
However, the immune system can also overdo it. It can lead to autoimmune diseases and allergies. Therefore, the immune system must be well controlled so that it does not cause damage in the body.
A good balance of the immune system is important for this: between the best possible defense against potentially harmful invaders on the one hand and the protection of the body’s own healthy tissue on the other.
Animal studies have shown that a selenium deficiency can impair the activity of so-called type 1 T helper cells (TH1). These are an important component of the cellular immune defense. In the event of an infection, TH1 cells secrete messenger substances that attract specific phagocytes. These then take up the infected cells and thereby render the pathogens harmless.
While the TH1 immune response is decisive in bacterial and viral infections, the TH2 immune response is more important in the case of an allergic or parasitic cause. Selenium deficiency can increase the risk of the TH2 immune response gaining the upper hand. If the immune response becomes unbalanced, this can promote the development of allergies and autoimmune diseases, among other things. An adequate selenium supply can help to maintain the balance of the immune system.
