type III hypersensitivity

medicine

Also known as: immune-complex reaction

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June 17, 2026

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Type III hypersensitivity, also known as immune-complex reactions, is a type of allergic response where tissue damage occurs due to the activation of complement. This happens when antigen-antibody complexes deposit in tissues, triggering an inflammatory response. This can lead to conditions like systemic lupus erythematosus, glomerulonephritis, and rheumatoid arthritis.1

These reactions can also be caused by inhaling antigens, leading to conditions such as farmer's lung or humidifier fever. Symptoms typically include chest tightness and fever, which subside upon removal from exposure. Type III reactions are distinct from Type I (IgE-mediated) and Type IV (cell-mediated) hypersensitivities, involving IgG and IgM antibodies and rapid onset.12

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immune system disorder
Type III hypersensitivity
Type III, or immune-complex, reactions are characterized by tissue damage caused by the activation of complement in response to antigen-antibody (immune) complexes that are deposited in tissues. The classes of antibody involved are the same ones that participate in type II reactions—IgG…
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Type III, or immune-complex, reactions are characterized by tissue damage caused by the activation of complement in response to antigen-antibody (immune) complexes that are deposited in tissues. The classes of antibody involved are the same ones that participate in type II reactions—IgG…
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poison
Allergies
…a third type of allergy, immune-complex hypersensitivity, the allergen-IgG complex precipitates in tissues, resulting in inflammation via complement fixation. Immune-complex hypersensitivity in the kidney results in an inflammatory injury of the glomeruli (glomerulonephritis), and in the lung it leads to a pneumonia-like condition known as hypersensitivity pneumonitis.
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…a third type of allergy, immune-complex hypersensitivity, the allergen-IgG complex precipitates in tissues, resulting in inflammation via complement fixation. Immune-complex hypersensitivity in the kidney results in an inflammatory injury of the glomeruli (glomerulonephritis), and in the lung it leads to a pneumonia-like condition known as hypersensitivity pneumonitis.
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