Immune complex

Immune complex diseases

An immune complex, sometimes called an antigen-antibody complex, is a molecule formed from the integral binding of an antibody to a soluble antigen.^[1] The bound antigen and antibody act as a unitary object, effectively an antigen of its own with a specific epitope. After an antigen-antibody reaction, the immune complexes can be subject to any of a number of responses, including complement deposition, opsonization,^[2] phagocytosis, or processing by proteases. Red blood cells carrying CR1-receptors on their surface may bind C3b-coated immune complexes and transport them to phagocytes, mostly in liver and spleen, and return to the general circulation.

Immune complexes may themselves cause illness when they are deposited in organs, for example, in certain forms of vasculitis. This is the third form of hypersensitivity in the Gell-Coombs classification, called type III hypersensitivity.^[3] Such hypersensitivity progressing to disease states produces the so-called immune complex diseases.

Immune complex deposition is a prominent feature of several autoimmune diseases, including systemic lupus erythematosus, cryoglobulinemia, rheumatoid arthritis, scleroderma and Sjögren's syndrome.^[4][5]

References

1. Cush, John; Kavanaugh, Arthur; Stein, Charles (2005). Rheumatology: Diagnosis and Therapeutics. Lippincott Williams & Wilkins. p. 78. ISBN 9780781757324.
2. Goldsby, Richard (2002). Immunology. Macmillan. p. 381. ISBN 9780716749479.
3. Barret, James (1980). Basic Immunology and its Medical Application (2 ed.). St.Louis: The C.V. Mosby Company. ISBN 0-8016-0495-8.
4. Lawley, Thomas; Moustopoulos, Haralampos (1979). "Demonstration of Circulating Immune Complexes in Sjögren's Syndrome". Journal of Immunology (The American Association of Immunologists) 123 (3): 1382–7. PMID 469255.
5. Wallace, Daniel, ed. (2004). The New Sjogren's Syndrome Handbook. Oxford University Press. p. 68. ISBN 9780198038481.