hypersensitetsreaktionerna

Hypersensitivitetsreaktionerna, or hypersensitivity reactions, refer to exaggerated or inappropriate immune responses that cause damage to the body. These reactions are classified into four main types, categorized by Gell and Coombs. Type I reactions, also known as immediate hypersensitivity or allergy, involve IgE antibodies and the release of histamine and other mediators, leading to symptoms like hives, asthma, and anaphylaxis. Examples include reactions to pollen, certain foods, and insect stings. Type II reactions, or cytotoxic hypersensitivity, involve IgG or IgM antibodies binding to antigens on cell surfaces, leading to cell destruction. This can occur in autoimmune hemolytic anemia or Rh incompatibility. Type III reactions, or immune complex hypersensitivity, arise when soluble antigen-antibody complexes deposit in tissues, activating complement and causing inflammation. Serum sickness and certain autoimmune diseases like lupus are examples. Type IV reactions, or delayed-type hypersensitivity, are cell-mediated, involving T lymphocytes rather than antibodies. These reactions typically develop 24-72 hours after exposure to an antigen, such as in a positive tuberculin skin test or contact dermatitis from poison ivy. Understanding the specific type of hypersensitivity is crucial for diagnosis and appropriate management. Treatment strategies vary depending on the type of reaction and can include avoidance of the trigger, antihistamines, corticosteroids, or immunosuppressants.