Every day we are confronted with bacteria and viruses and do not even notice it.
The reason is our immune system, which works around the clock to keep us fit and healthy, especially during the cold season.
By immune system we mean the complex interactions between various organs, tissues and cell types in our body. These include the spleen, bone marrow, thymus and gut. The basic task of the immune system is to recognise foreign substances and eliminate them from our body. For this we have several lines of defence that work together against the intruders.
The mechanical barrier
The first barrier is our skin and mucous membranes, because viruses and bacteria first have to get into our body. A large number of protective mechanisms (acidic pH on the skin, tightly packed cells, stomach acid, etc.) make things very difficult for the intruders right from the start. From time to time, however, some viruses or bacteria manage to overcome these mechanical, chemical and physical barriers and enter the body.
The innate immune system
If a pathogen or another foreign substance has made it past the first line of defence into the body, the immune system’s attack really gets going: immune cells (phagocytes, granulocytes and natural killer cells) migrate to the site of entry, engulf the pathogens and release messenger substances that eliminate the intruders and can attract further immune cells. This reaction takes place immediately after entry, so that the bacteria and viruses cannot spread in the first place.
However, the immune cells of the innate immune system attack rather non-specifically and reach their limits with many pathogens. For this reason, during these attacks the immune cells also take up components of the pathogens and transport them to the lymph nodes. There, specialised immune cells are activated when these components of the intruders are presented to them. The acquired immune system now helps to fight the intruders.
The acquired immune system
The acquired immune system can eliminate the intruders very specifically. While the innate immune system exists from birth, the acquired immune system has to develop over the course of life.
A central role is played here by the white blood cells that become T cells and B cells. It is precisely these two cell types that are activated by the immune cells which are first on the scene of an infection and then present the pathogen components to the cells of the acquired immune system. In this phase, T cells take on the role of organiser of the immune response, while the B cells produce antibodies that act very specifically against the pathogens and carry out their task of fighting the intruders conscientiously.
After the pathogens have been fought off, some T and B cells become memory cells. This means that the immune system can react faster the next time it comes into contact with the pathogens, and you are protected straight away. Vaccinations work in the same way.
How do vaccinations work?
With vaccinations there are 2 options: active or passive immunisation.
With active vaccination, components of the virus are injected, against which the immune system forms antibodies and also memory cells. If you then come into contact with the pathogen, the memory cells are activated very quickly and the intruders are eliminated directly. An active vaccination therefore gives you lifelong protection against these pathogens.
With passive immunisation the body does not produce the protective antibodies itself; instead they are injected with the vaccination. This gives you short-term protection if you come into contact with the virus or bacterium. This protection is therefore not lifelong, but only for an acute immune defence.
So our immune system is our protector in every situation in life, but it can also be weakened, for example during the cold season. The good news is that we can also support our immune system. For tips on how to strengthen your immune system, take a look at this article: “10 tips to strengthen your immune system”
