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A complement receptor is a receptor of the complement system, a part of the mediated innate immune system. Complement receptors are responsible for detecting pathogens by mechanisms not mediated by antibodies. Complement activity is not antigen sensitive, but can be triggered by specific antigens. Therefore, complement (a group of proteins in the serum that help achieve phagocytosis and lysis of antigens) is also part of the humoral immune system.
All four complement receptors bind to complement component 3 or complement component 4 fragments on pathogen surface, but they are different in functions. Complement receptor (CR) 1, 3, and 4 work as opsonin. On the other hand, CR2 is a kind of B cell co-receptor.
|CR3||Macrophage-1 antigen or "integrin alphaMbeta2"||CD11b+CD18|
|CR4||Integrin alphaXbeta2 or "p150,95"||CD11c+CD18|
Defects in these receptors can be associated with disease.
- Peter Parham, The Immune System (2nd ed.), Taylor&Francis
- "Complement Receptor Deficiency: eMedicine Dermatology". Retrieved 2010-12-07.