Overfølsomhedsreaktioner

Overfølsomhedsreaktioner, often referred to as hypersensitivity reactions, are a group of conditions where the immune system overreacts to substances that are normally harmless. These reactions can manifest in various ways, from mild skin rashes to life-threatening anaphylaxis. The immune system's exaggerated response can be triggered by allergens, which are foreign substances like pollen, certain foods, medications, or insect venom.

There are four main types of hypersensitivity reactions, classified by Gell and Coombs. Type I reactions are immediate, IgE-mediated responses, commonly seen in allergies like hay fever and asthma. Type II reactions involve antibodies that target cells or tissues, leading to conditions like autoimmune hemolytic anemia. Type III reactions are immune complex-mediated, where antigen-antibody complexes deposit in tissues, causing inflammation as seen in serum sickness. Type IV reactions are delayed, cell-mediated responses, such as contact dermatitis from poison ivy or a positive tuberculin skin test.

Diagnosis of hypersensitivity reactions often involves a detailed medical history, physical examination, and specific tests such as skin prick tests, blood tests to detect specific antibodies (like IgE), or patch tests for delayed reactions. Management strategies depend on the type and severity of the reaction. They can include avoidance of the trigger, antihistamines, corticosteroids, immunosuppressants, or in severe cases, emergency treatments like epinephrine. Understanding the underlying mechanisms is crucial for effective prevention and treatment of these diverse immune-mediated conditions.