Complement receptor
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A complement receptor is a receptor of the complement system, part of the innate immune system. Complement receptors bind proteins of the complement system, and can thus detect pathogens without mediation by antibodies. Complement activity is not antigen sensitive, but can be triggered by specific antigens.[1]
Complement receptors
Many leukocytes express complement receptors on their surface, particularly monocytes and macrophages. All four complement receptors bind to complement component 3 or complement component 4 fragments on pathogen surface, but the receptors have different functions. Complement receptor (CR) 1, 3, and 4 work as opsonins (stimulate phagocytosis), whereas CR2 is expressed only on B cells as a co-receptor.
Red blood cells (RBCs) also express CR1. With these receptors, RBCs bring antigen-antibody complex in blood to liver and spleen for degradation.[2]
| CR # | Name | Ligand[1] | CD |
| CR1 | - | C3b, C4b, iC3b | CD35 |
| CR2 | - | C3d, iC3b, C3dg, Epstein-Barr virus | CD21 |
| CR3 | Macrophage-1 antigen or "integrin αMβ2" | iC3b | CD11b+CD18 |
| CR4 | Integrin alphaXbeta2 or "p150,95" | iC3b | CD11c+CD18 |
| - | C3a receptor | C3a | - |
| - | C5a receptor | C5a | CD88 |
Clinical significance
Defects in these receptors can be associated with disease.[3]
See also
References
- ^ a b Janeway, CA Jr; Travers P; Walport M; et al. (2001). "The complement system and innate immunity". Immunobiology: The Immune System in Health and Disease. New York: Garland Science. Retrieved 29 December 2017.
- ^ Peter Parham, The Immune System (2nd ed.), Taylor&Francis
- ^ "Complement Receptor Deficiency: eMedicine Dermatology". Retrieved 7 December 2010.
External links
- Complement+receptors at the U.S. National Library of Medicine Medical Subject Headings (MeSH)