Überempfindlichkeitsreaktionen

Überempfindlichkeit is a German term that translates to hypersensitivity in English. It refers to an exaggerated or inappropriate immune response to an antigen that is normally harmless. This can manifest in various ways, affecting different parts of the body and leading to a wide range of symptoms.

There are four main types of hypersensitivity reactions, classified by Gell and Coombs. Type I, or immediate hypersensitivity, involves IgE antibodies and is responsible for allergies like hay fever, asthma, and anaphylaxis. Symptoms appear rapidly, often within minutes, after exposure to the allergen.

Type II hypersensitivity, or cytotoxic hypersensitivity, involves IgG or IgM antibodies that target antigens on cell surfaces. This can lead to the destruction of cells, as seen in certain autoimmune diseases like hemolytic anemia or transfusion reactions.

Type III hypersensitivity, or immune complex hypersensitivity, occurs when antigen-antibody complexes deposit in tissues, triggering inflammation. Conditions like lupus erythematosus and serum sickness are examples of this type.

Type IV hypersensitivity, also known as delayed-type hypersensitivity, is cell-mediated and involves T lymphocytes. It typically appears 24 to 72 hours after exposure to an antigen, such as in contact dermatitis from poison ivy or a positive tuberculin skin test. Understanding the specific type of Überempfindlichkeit is crucial for accurate diagnosis and effective treatment.