The immune system can best be compared to a well-organized army, always ready to protect the body from any invaders. This impressive defense force is made up of various specialized units that work together harmoniously to fight infections and keep the body healthy. A crucial factor for the optimal development and functionality of this complex defense system is early and regular contact with a wide variety of microorganisms. This contact trains the immune system, makes it more resilient and prepares it to effectively fight a wide range of pathogens. Children who grow up in an environment rich in microbial diversity therefore often have a stronger and more responsive immune system that better protects them against disease.
The components of the immune system
The immune system consists of the innate and the acquired immune defenses. The innate immunity is immediately available and provides a general defense, while the acquired immunity reacts specifically to certain pathogens and forms memory cells to enable a rapid and targeted defense in the future.
main components of the immune system
Leukocytes, also called white blood cells, play a central role in the immune system. These cells patrol the body looking for invaders. There are several types of leukocytes, including granulocytes, which contain enzymes to destroy microbes, lymphocytes, which produce antibodies and kill infected cells, and monocytes, which develop into macrophages and dendritic cells to engulf pathogens and initiate the immune response.
Lymphatic tissues and organs, such as lymph nodes, spleen, tonsils and the thymus, are crucial for activating and housing immune cells. Lymph nodes filter lymph fluid, the spleen breaks down old blood cells and stores white blood cells, the tonsils protect against infections in the mouth and throat, and the thymus is responsible for the maturation of T cells.
Antibodies are Y-shaped proteins produced by B cells that specifically attack pathogens. They mark invaders for destruction by other immune cells. The complement system, consisting of over 30 proteins in the blood, works with antibodies to destroy invaders and promote inflammation.
These components work together to protect the body from viruses, bacteria, fungi and other harmful substances. The interaction of these cells and molecules is crucial for maintaining our health.
Development of the immune system over the course of life
The development of the immune system begins in the embryonic phase and continues after birth. Here are the most important stages of this development:
Prenatal phase : In the embryonic phase, the basic structures of the immune system are formed, including the hematopoietic stem cells from which all blood cells arise. In the fetal phase, the immune system begins to produce the first immune cells, but the ability to mount an immune response is still limited. The fetus is protected by the maternal immune system.
Birth and early childhood : The newborn's contact with the outside world marks the beginning of immune development. In the first few days after birth, the child is brought into contact with bacteria and microorganisms from the environment. Breast milk contains antibodies, enzymes and other immune substances that strengthen the infant's passive immune defenses and protect against infections.
Infancy and early childhood : The thymus reaches its maximum size in childhood and is responsible for the maturation of T lymphocytes. The body develops an immune memory that allows it to respond more quickly and effectively after exposure to certain pathogens.
Childhood and adolescence : The immune response is constantly adapting to the variety of environmental antigens to which the child is exposed. This contributes to the expression of innate and acquired immunity. Hormonal changes during puberty can influence the immune response.
Adulthood : The immune system stabilizes and optimizes its functions in adulthood. It remains active throughout life to protect the body from infections.
The Role of the Immune System in Certain Diseases
The immune system plays a central role in fighting infections and diseases. Here are some categories of diseases that are related to the immune system:
Immunodeficiency diseases : These occur when the immune system is impaired due to genetic defects or other factors. Examples are primary or acquired immunodeficiency.
Autoimmune diseases : In these diseases, the immune system mistakenly attacks the body's own cells and tissues. Examples include rheumatoid arthritis, lupus and type 1 diabetes.
Allergies : Allergies are overreactions of the immune system to normally harmless substances such as pollen or food.
Inflammatory diseases : These are caused by excessive immune responses and chronic inflammation, such as Crohn's disease and ulcerative colitis.
Cancer : A weakened immune system can increase the risk of cancer. Some cancers directly affect the immune system, such as leukemia and lymphoma.
HIV/AIDS : HIV specifically infects and damages immune cells, especially CD4 T cells, and if left untreated leads to a weakened immune system known as AIDS.
Immune reactions in organ transplants : The immune system can recognize transplanted organs as foreign and reject them, which is why immunosuppressants are used.
The intestinal microbiome and the immune system
The gut microbiome plays a crucial role in regulating and supporting the immune system. The immune defense and the gut microbiome influence each other. The microbiome helps shape and regulate the immune system. It acts as a barrier against harmful pathogens and promotes an appropriate immune response. A balanced and diverse microbiome in the gut promotes a balanced immune response and prevents excessive inflammation. It supports the development of immune tolerance to prevent autoimmune diseases and produces metabolites that modulate the function of immune cells. The microbiome also influences immune responses in other tissues and organs, such as the gut-lung or gut-brain axis.
The importance of a diverse environment for the development of a functioning immune system
Early exposure to a high diversity of microorganisms is crucial for the development of a well-functioning immune defense. Exposure to microorganisms promotes the maturation and effectiveness of immune cells. Early exposure to bacteria contributes to the formation of a healthy gut microbiota, which is important for immune regulation. Early exposure helps develop immune tolerance to prevent excessive reactions to harmless substances. The newborn's exposure to microorganisms during birth supports the development of a functional immune system. Balanced exposure to bacteria promotes the development of a stable immune ecosystem. Appropriate exposure can reduce the risk of allergies and autoimmune diseases.
What role does the immune system play in the development of allergies?
Allergies are inappropriate reactions of the immune system to normally harmless substances called allergens. A well-functioning immune system and the development of allergies are closely linked. In people with allergies, the immune system reacts oversensitively to certain allergens such as pollen, dust mites, animal hair or food proteins. Sensitization occurs upon initial exposure, whereby the immune system falsely recognizes the allergen as a threat and produces specific antibodies.
Allergies result from a dysregulation of the immune response. Instead of fighting harmful pathogens, the immune system overreacts to harmless substances. This inappropriate immune system reaction is responsible for allergic symptoms. The tendency to allergies can be genetic. Environmental factors, such as exposure to allergens in childhood, can influence the risk. A complex interplay of genetic and environmental factors contributes to the development of allergies.
Treatment often involves avoiding allergens and using medications to relieve symptoms. In some cases, immunotherapies can be used to modulate the immune system's excessive response and reduce it in the long term. Probiotics can also be effective in preventing and treating allergies.
The immune system and probiotics
Probiotics have positive effects on the immune system. They support the balance of the intestinal microbiota and promote the integrity of the intestinal barrier. Probiotics influence the activity of immune cells and the production of immune-regulatory molecules. They stimulate the production of antibodies, especially IgA, and inhibit the growth of pathogenic microorganisms. Probiotics can increase the effectiveness of vaccinations and have anti-inflammatory properties.
Probiotic strains to stabilize the immune system
- Lactobacillus acidophilus : Promotes healthy intestinal flora and modulates the immune system.
- Bifidobacterium bifidum : Supports intestinal health and strengthens the immune system.
- Lactobacillus rhamnosus : Modulates the immune response and is used to prevent infections and allergies.
- Bifidobacterium longum : Promotes intestinal health and reduces inflammation.
- Saccharomyces boulardii : Supports intestinal health and prevents diarrhea.
- Lactobacillus casei : Regulates the activity of immune cells.
- Streptococcus salivarius : Stimulates the oral immune response and protects against respiratory infections.
- Lactobacillus paracasei : Relieves allergic symptoms through immunomodulating properties.
The immune system – diversity is important!
The immune system is a complex network of different components that work together to protect the body from infection. A well-developed immune system requires early exposure to a wide variety of microorganisms and can be further strengthened with probiotic support. Probiotics have numerous positive effects on immune function and can help keep the immune system in balance. A healthy lifestyle, a balanced diet and adequate environmental exposure contribute significantly to strengthening the immune system.
