How passive antibodies suppress the production of active antibodies

Active and passive immunization: a wake-up call to the immune system

In order to protect the body from attacks by microorganisms such as bacteria, viruses, fungi and parasitic protozoa (such as malaria), the immune system must distinguish known from unknown molecules. Because pathogens that have penetrated, as well as incorrectly mutated endogenous cells, reveal themselves to unknown molecules. There are two different mechanisms for this immune defense: the unspecific and the specific defense. Both do not run in isolation from each other, but interlock and protect the body from diseases.

Nonspecific immune defense all innate barriers, disinfecting fluids and immune reactions that are not specialized in certain germs are named. They protect people from germs and foreign bodies from birth. These include, for example, the skin, the mucus in the bronchi, the fluid film on the eyes or the gastric juice and pancreas. If pathogens break through these superficial barriers or if they survive disinfection in the digestive tract, they encounter internal molecular defense mechanisms such as antimicrobial substances and the membrane attack complex. The latter punches holes in bacteria and is also called complement. Cells also take part in the defense. These include phagocytes and certain white blood cells (neutrophils) that eject mesh-like traps (called NETs). Fever can also help defensive reactions because it blocks some pathogens from multiplying while helping other parts of the immune system work faster.

The specific immune defense is specifically tailored to a specific pathogen. However, it must be acquired or learned, it is not innate. That's why it's called adaptive immune defense. It is acquired (as passive immunization) if a child receives maternal antibodies before birth or with breast milk, or if a doctor gives an antibody preparation. It is learned (as active immunization), if the immune system has to deal with the invading pathogen in the event of illness or through a vaccination. The specific immune response is characterized by a great ability to adapt and remember. Humans expand their immunological memory in the course of their lives. In this way, the body can react quickly to an increasing number of pathogens with repeated infections.