Immune System: Sequence of an Immune Reaction

The immune reaction is your body's response to pathogens such as Bacteria or Viruses.
When a pathogen enters your body, specialized defense cells recognize it as "foreign".
Defense substances (antibodies) and other protective mechanisms are then activated to combat the invader.
Some defense cells engulf and eat the pathogens, while others destroy infected body cells.
After successful defense, the immune system "remembers" the pathogen to react more quickly on the next encounter.
There is an innate defense which acts immediately and an adaptive defense which is more targeted but takes a bit longer.
This immune reaction protects you from becoming ill or helps you recover.
⚙ immunreaktion

The sequence of an immune reaction starts with the recognition of an invader such as bacteria, viruses, or fungi.
These pathogens have specific structures on their surface, called antigens.
Immune system cells like Macrophages or Dendritic Cells are present in the body and recognize these antigens as foreign. They take up the pathogen, break it apart, and present the antigens like a warning sign on their cell surface.
This presentation alerts other immune system cells.
This process ensures that the body can distinguish between own and foreign structures to enable a precise defense.
⚙ erreger

Once the pathogen is recognized, the actual defense begins. Various parts of the immune system work together to fight the invader:
- Specific Immune Defense: T-cells and B-cells are activated. Helper T-cells stimulate the activation of other immune cells, while cytotoxic T-cells destroy infected body cells.
- Non-specific Immune Defense: Cells such as natural killer cells and macrophages immediately attack the pathogen. Inflammatory reactions—detectable by redness, swelling, heat, and pain—are triggered to contain the pathogen.
- Chemical substances like interferons and cytokines also support the defense process.
This division of labor ensures that pathogens are attacked as efficiently as possible.
⚙ abwehrreaktion

B-cells are crucial for the formation of antibodies, special proteins that bind specifically to the antigens of pathogens.
After B-cells encounter the pathogen and are supported by helper T-cells, they differentiate into so-called plasma cells.
- Plasma cells produce large amounts of antibodies.
- The antibodies mark pathogens, allowing other immune cells to recognize and eliminate them easily.
- Some antibodies directly block important functions of the pathogen, such as preventing entry into body cells.
The antibody process takes several days, but enables the immune system to develop a highly specific and effective defense against the current pathogen.
⚙ antikorper

After surviving the infection, the immune system remains vigilant.
Memory cells, called memory cells, develop during the immune reaction:
- Memory T-cells and memory B-cells persist for years or decades.
- When encountering the same pathogen again, these cells recognize the antigen quickly and can initiate a much faster and more effective defense.
Process Time on First Contact Time on Second Contact
Activation slow very fast
Antibody production after several days often within hours
This memory effect is the basis for vaccinations, which train the immune system without causing a real infection.
⚙ erinnerung

Process	Time on First Contact	Time on Second Contact
Activation	slow	very fast
Antibody production	after several days	often within hours