Arthus phenomenon, also known as Arthus reaction or localized immune complex reaction, is a hypersensitivity response caused by the formation of immune complexes in the blood vessels of a specific tissue or organ. This immunological event is named after French immunologist Maurice Arthus, who first described this phenomenon in the early 20th century.
Arthus phenomenon occurs when an individual is repeatedly exposed to an antigen, such as through vaccinations or insect bites. After initial exposure to the antigen, the immune system produces antibodies against it. However, subsequent exposure to the same antigen triggers the formation of immune complexes, which are aggregates of antigens and antibodies.
The accumulation of immune complexes in the affected tissue leads to activation of the complement system and subsequent inflammatory response. This immune-mediated inflammation results in localized tissue damage, characterized by the permeability of blood vessels, swelling, redness, and pain.
Arthus phenomenon is typically seen in skin tissues, but it can also occur in other organs like the lungs and kidneys. It is considered a type III hypersensitivity reaction, as it involves deposition of immune complexes and subsequent complement activation, leading to inflammation.
The severity of the Arthus reaction can vary from mild to severe, depending on the amount and frequency of antigen exposure, as well as individual immune responses. Treatment usually involves symptomatic relief, such as pain management and anti-inflammatory medications.
In summary, Arthus phenomenon refers to a localized immune complex reaction causing tissue damage due to the formation of immune complexes, which triggers an inflammatory response upon antigen re-exposure.
