Type III hypersensitivity

Type III hypersensitivity is a type of immune response that occurs when the immune system overreacts to an antigen, leading to tissue damage. This type of hypersensitivity is also known as immune complex-mediated hypersensitivity, as it involves the formation of immune complexes that can deposit in various tissues and trigger inflammation.

Overview

Type III hypersensitivity reactions occur when there is an excess of antigen, leading to the formation of immune complexes in the blood. These complexes can deposit in various tissues, including the kidney, skin, joints, and blood vessels, where they can trigger an inflammatory response. This can lead to a variety of symptoms, depending on the location of the immune complex deposition.

Mechanism

The mechanism of type III hypersensitivity involves the formation of immune complexes, which are aggregates of antibodies and antigens. These complexes can circulate in the blood and deposit in various tissues, where they can trigger an inflammatory response. This is mediated by the activation of complement, a system of proteins in the blood that enhances the ability of antibodies to clear pathogens and damaged cells.

Clinical significance

Type III hypersensitivity reactions can lead to a variety of conditions, including glomerulonephritis, vasculitis, serum sickness, and Arthus reaction. These conditions can be severe and potentially life-threatening, particularly if they involve vital organs such as the kidneys.

Treatment

Treatment for type III hypersensitivity reactions typically involves managing the underlying cause of the immune response. This can include avoiding the antigen that triggered the reaction, using medications to suppress the immune response, or treating the symptoms of the reaction.

See also

• Type I hypersensitivity
• Type II hypersensitivity
• Type IV hypersensitivity
• Hypersensitivity vasculitis
• Immune complex

References

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