Final answer:
Henoch-Schönlein purpura involves the deposition of IgA immune complexes as part of a type III hypersensitivity inflammatory reaction.
Step-by-step explanation:
Henoch Schönlein purpura (HSP), also known as IgA vasculitis, is a type of autoimmune disorder that affects the small blood vessels in the body, leading to inflammation and damage. The condition is characterized by the deposition of IgA (immunoglobulin A) immune complexes in the blood vessels, which ultimately leads to various symptoms and complications.
IgA is an antibody that plays a crucial role in the immune system's defense against bacterial and viral infections. However, in individuals with HSP, IgA immune complexes are deposited in the walls of small blood vessels, particularly in the skin, joints, kidneys, and gastrointestinal tract. These immune complexes trigger an inflammatory response that results in various symptoms.
The deposition of IgA immune complexes in the blood vessels causes capillaritis, which refers to inflammation and damage to the capillaries. Capillaries are the smallest blood vessels in the body that connect arteries and veins. They are responsible for delivering oxygen and nutrients to the tissues and removing waste products. Capillaritis leads to leakage of fluid, red blood cells, and other substances into the surrounding tissue, resulting in purpura or bruising.
Purpura is a common symptom of HSP, characterized by the appearance of reddish-purple spots or patches on the skin. These spots are caused by the leakage of blood into the tissue due to capillaritis. Purpura can occur anywhere on the body but is commonly seen on the legs and buttocks.
In addition to purpura, HSP can cause various other symptoms depending on which organs are affected by capillaritis. Skin involvement is common and can result in itching, hives, and blisters. Joint involvement can lead to pain, swelling, and stiffness. Kidney involvement is a serious complication of HSP as it can result in glomerulonephritis, a condition characterized by inflammation and scarring of the kidneys' filtering units (glomeruli). Glomerulonephritis can lead to kidney failure if left untreated. Gastrointestinal involvement can result in abdominal pain, diarrhea, and bleeding.
The exact cause of HSP is not fully understood, but it is believed to be triggered by an infection or an allergic reaction. The condition is more common in children than adults and affects males more frequently than females. The diagnosis of HSP is based on clinical presentation and laboratory tests that confirm the deposition of IgA immune complexes in the blood vessels. Treatment for HSP involves supportive care for symptomatic relief and management of complications such as kidney involvement. In severe cases, corticosteroids or immunosuppressive medications may be necessary to suppress the immune system's inflammatory response.
In conclusion, Henoch Schönlein purpura is a type of autoimmune disorder characterized by the deposition of IgA immune complexes in small blood vessels leading to capillaritis and various symptoms such as purpura, joint pain, kidney involvement, and gastrointestinal symptoms. The exact cause of HSP is not fully understood, but it is believed to be triggered by an infection or an allergic reaction. Treatment for HSP involves supportive care for symptomatic relief and management of complications such as kidney involvement.