Abstract
The immune system is a human defense system that can be adapted to external conditions and is present ubiquitously throughout the organism. Its main purpose is to prevent damage caused by pathogens or toxins. In addition, it is capable of recognizing and destroying defective or degenerated endogenous cells. The immunological network in the body consists of various organs and organ systems, different immunoactive cell types as well as extra- and intracellular signaling molecules and signal complexes. The immune system is divided into the innate immune system and the acquired immune system. Pathological conditions, which may be short- or long-lasting, range from the congenital disorders of autoinflammation to the numerous autoimmune diseases, triggered by various stimuli. From a treatment perspective, nonspecific immunosuppressants or direct immune cell inhibitors or antibodies can be used for excessive reactions.