A complement receptor is a membrane-bound receptor belonging to the complement system, which is part of the innate immune system
Complement receptors bind effector protein fragments that are produced in response to antigen-antibody complexes or damage-associated molecules. Complement receptor activation contributes to the regulation of inflammation, leukocyte extravasation, and phagocytosis; it also contributes to the adaptive immune response. Different complement receptors can participate in either the classical complement pathway, the alternative complement pathway, or both.
- VM (29 January 2014). “Complement and its receptors: new insights into human disease”. Annual Review of Immunology. 32: 433–59. doi:10.1146/annurev-immunol-032713-120154. PMID 24499275.
- Verschoor A, Kemper C, Köhl J (15 September 2017). “Complement Receptors”. eLS: 1–17. doi:10.1002/9780470015902.a0000512.pub3. ISBN 9780470015902.
- Carroll MC (December 2008). “Complement and humoral immunity”. Vaccine. 26 Suppl 8 (Suppl 8): I28-33. doi:10.1016/j.vaccine.2008.11.022. PMC 4018718. PMID 19388161.
- Janeway Jr CA, Travers P, Walport M, Shlomchik MJ (2001). “The complement system and innate immunity”. Immunobiology: The Immune System in Health and Disease (5th ed.). New York: Garland Science. Retrieved 17 June 2020.
Expression and function
White blood cells, particularly monocytes and macrophages, express complement receptors on their surface. All four complement receptors can bind to fragments of complement component 3 or complement component 4 coated on pathogen surface, but the receptors trigger different downstream activities. Complement receptor (CR) 1, 3, and 4 function as opsonins which stimulate phagocytosis, whereas CR2 is expressed only on B cells as a co-receptor.
- VM (29 January 2014). “Complement and its receptors: new insights into human disease”. Annual Review of Immunology. 32: 433–59. doi:10.1146/annurev-immunol-032713-120154. PMID 24499275.
Red blood cells (RBCs) also express CR1, which enables RBCs to carry complement-bound antigen-antibody complexes to the liver and spleen for degradation.
- Parham P (2005). The Immune System (2nd ed.). Garland Science. ISBN 9780815340935.
| CR # | Name | Molecular weight (Da, approx.) | Ligand | CD | Major cell types | Major activities |
|---|---|---|---|---|---|---|
| CR1 | Complement receptor 1 | 190,000–250,000 | C3b, C4b, iC3b | CD35 | B, E, FDC, Mac, M0, PMN | Immune complex transport (E); phagocytosis (PMN, Mac); immune adhesion (E); cofactor and decay-acceleration; secondary Epstein-Barr virus receptor |
| CR2 | Complement receptor 2 | 145,000 | C3d, iC3b, C3dg, Epstein-Barr virus | CD21 | B, FDC | B cell coactivator, primary Epstein-Barr virus receptor, CD23 receptor |
| CR3 | Macrophage-1 antigen or “integrin αMβ2“ | 170,000 α chain + common 95,000 β chain | iC3b | CD11b + CD18 | FDC, Mac, M0, PMN | Leukocyte adherence, phagocytosis of iC3b-bound particles |
| CR4 | Integrin alphaXbeta2 or “p150,95” | 150,000 α chain + common 95,000 β chain | iC3b | CD11c + CD18 | D, Mac, M0, PMN | Leukocyte adhesion |
| C3AR1 | C3a receptor | 75,000 | C3a | – | Endo, MC, Pha | Cell activation |
| C5AR1 | C5a receptor | 50,000 | C5a | CD88 | Endo, MC, Pha | Cell activation, immune polarization, chemotaxis |
| C5AR2 | C5a receptor 2 | 36,000 | C5a | – | Chemotaxis |
Clinical significance
Main articles: Complement system § Role in disease, Classical complement pathway § Clinical significance, and Alternative complement pathway § Role in disease
Deficits in complement receptor expression can cause disease. Mutations in complement receptors which alter receptor function can also increase risk of certain diseases.
- VM (29 January 2014). “Complement and its receptors: new insights into human disease”. Annual Review of Immunology. 32: 433–59. doi:10.1146/annurev-immunol-032713-120154. PMID 24499275.
- Schwartz RA, Thomas I. “Complement Receptor Deficiency: eMedicine Dermatology”. Medscape. Retrieved 7 December 2010.
See also
References
- VM (29 January 2014). “Complement and its receptors: new insights into human disease”. Annual Review of Immunology. 32: 433–59. doi:10.1146/annurev-immunol-032713-120154. PMID 24499275.
- Verschoor A, Kemper C, Köhl J (15 September 2017). “Complement Receptors”. eLS: 1–17. doi:10.1002/9780470015902.a0000512.pub3. ISBN 9780470015902.
- Carroll MC (December 2008). “Complement and humoral immunity”. Vaccine. 26 Suppl 8 (Suppl 8): I28-33. doi:10.1016/j.vaccine.2008.11.022. PMC 4018718. PMID 19388161.
- Janeway Jr CA, Travers P, Walport M, Shlomchik MJ (2001). “The complement system and innate immunity”. Immunobiology: The Immune System in Health and Disease (5th ed.). New York: Garland Science. Retrieved 17 June 2020.
- Parham P (2005). The Immune System (2nd ed.). Garland Science. ISBN 9780815340935.
- Schwartz RA, Thomas I. “Complement Receptor Deficiency: eMedicine Dermatology”. Medscape. Retrieved 7 December 2010.
External links
- Complement+receptors at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
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