Arthusreaktiossa

Arthusreaktio, also known as the Arthus reaction, is a type of localized immune complex-mediated hypersensitivity reaction. It occurs when immune complexes—antigen-antibody complexes—deposit in tissues and trigger an inflammatory response. This reaction is classified as Type III hypersensitivity according to the Gell and Coombs classification system.

The Arthus reaction typically develops within a few hours after exposure to a specific antigen in individuals who have pre-existing high levels of circulating antibodies. The formation of immune complexes activates the complement system, leading to the recruitment of inflammatory cells such as neutrophils. These cells release enzymes and reactive oxygen species that damage surrounding tissues, resulting in localized swelling, redness, pain, and tissue necrosis.

Clinically, the Arthus reaction can be observed in various contexts, including repeated injections of vaccines or antigens, certain autoimmune conditions, and allergic reactions. It is often used as a research model to study immune complex diseases and hypersensitivity mechanisms.

Pathologically, the reaction involves the deposition of immune complexes primarily in small blood vessel walls, leading to vasculitis. Histological examination typically reveals neutrophilic infiltration, fibrinoid necrosis, and complement activation within the affected tissues.

Treatment of Arthus reactions often involves the administration of anti-inflammatory agents such as corticosteroids, and avoidance of further exposure to the triggering antigen. While usually self-limited, severe cases may require medical intervention to prevent extensive tissue damage.

Understanding the Arthus reaction is important in fields such as immunology, allergy, and vaccine development, as it highlights the potential adverse effects of immune complex formation and the importance of immune regulation in preventing tissue injury.