Where does immunology come from?

The cells of the immune system Immunology for everyone

Our entire blood-forming system develops from blood stem cells in the bone marrow. Such stem cells can develop into a wide variety of cell types with different tasks and functions.

Our immune system contains a large variety of white blood cells called leukocytes, which make up a large part of our immune system. These cells can be divided into three large groups: the granulocytes (proportion approx. 50-70%), the lymphocytes (proportion approx. 20-40%) and the monocytes (proportion approx. 1-6%). Leukocytes can move independently in the body and, in contrast to red blood cells (erythrocytes), also have a cell nucleus.


The cells of the immune system

Lymphocytes

The lymphocytes are the most important group among the immune cells. They are the basis for the acquired immune system and immunological memory. Every person has around a trillion lymphocytes in their bodies that are constantly on the lookout for pathogens.

In order to turn these cells into effective weapons in the fight against pathogens, they must have certain properties on their cell surface, so-called receptors. These allow the cells to recognize their target of attack. But every lymphocyte has only one specific receptor on its cell surface, but multiple copies of it. Thus, each cell can only recognize one specific antigen. In order to fight pathogens as quickly and effectively as possible, the body stores a few copies of antigens that have already occurred. If this should reappear, the immune cells with the appropriate receptors are produced millions of times and can thus destroy the pathogen.

Lymphocytes include natural killer cells, T lymphocytes and B lymphocytes and their more specialized successor cells.

B lymphocytes develop in the bone marrow and then migrate to search for their antigen. They mediate the so-called humoral immune response by producing large quantities of antibodies as plasma cells.

T lymphocytes also originate in the bone marrow and develop in the thymus. They are responsible for the cellular immune response. They attack antigens directly and also destroy their own body cells that are affected by viruses or mutations. T cells make up approximately 70% of the immune cells of all lymphocytes.

NK cells are able to detect and kill tumor cells or virus-infected cells. They are part of the innate immune system.

Monocytes and Macrophages belong to the group of phagocytes. They are irreplaceable for the regulation of the immune response and secrete a variety of chemical messenger substances to regulate the strength of the immune response. Monocytes patrol the bloodstream. As soon as they migrate into tissue, they develop into macrophages.

Dendritic cells can form from monocytes as well as from precursor cells of T cells. They have a very specific structure and shape that enable them to catch pathogens, digest them and present fragments of them again on their surface for other immune cells. They are mainly found in large numbers on surface tissue, such as the skin, or in the throat, but also in the inner mucous membranes.

Granulocytes make up the largest group of leukocytes. They are divided into different subgroups, each of which has different tasks. What they have in common is that all granulocytes contain filled granules in their cells. These are filled with various enzymes and bacteria-killing substances. If necessary, they release the content to their surroundings and thus fight pathogens.