Complement receptor

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Complement receptor
Identifiers
SymbolComplement receptor
Membranome 116

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. [1] Complement receptor activation contributes to the regulation of inflammation, leukocyte extravasation, and phagocytosis; it also contributes to the adaptive immune response. [2] [3] Different complement receptors can participate in either the classical complement pathway, the alternative complement pathway, or both. [4]

Contents

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. [1] 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.

Red blood cells (RBCs) also express CR1, which enables RBCs to carry complement-bound antigen-antibody complexes to the liver and spleen for degradation. [5]

CR #NameMolecular weight (Da, approx.) [1] Ligand [4] CD Major cell types [4] a Major activities [1]
CR1 Complement receptor 1 190,000–250,000C3b, C4b, iC3bCD35B, E, FDC, Mac, M0, PMNImmune complex transport (E); phagocytosis (PMN, Mac); immune adhesion (E); cofactor and decay-acceleration; secondary Epstein-Barr virus receptor
CR2 Complement receptor 2 145,000C3d, iC3b, C3dg, Epstein-Barr virusCD21B, FDCB cell coactivator, primary Epstein-Barr virus receptor, CD23 receptor
CR3 Macrophage-1 antigen or "integrin αMβ2"170,000 α chain + common 95,000 β chainiC3b CD11b+CD18 FDC, Mac, M0, PMNLeukocyte adherence, phagocytosis of iC3b-bound particles
CR4 Integrin alphaXbeta2 or "p150,95"150,000 α chain + common 95,000 β chainiC3b CD11c+CD18 D, Mac, M0, PMNLeukocyte adhesion
C3AR1 C3a receptor 75,000C3a–Endo, MC, PhaCell activation
C5AR1 C5a receptor 50,000C5aCD88Endo, MC, PhaCell activation, immune polarization, chemotaxis
C5AR2 C5a receptor 2 36,000C5a–Chemotaxis
a. ^ B: B cell. E: erythrocyte. Endo: endothelial cell. D: dendritic cell. FDC: follicular dendritic cell. Mac: macrophage. MC: mast cell. M0: monocyte. Pha: phagocyte. PMN: polymorphonuclear leukocyte.

Clinical significance

Deficits in complement receptor expression can cause disease. [6] Mutations in complement receptors which alter receptor function can also increase risk of certain diseases. [1]

See also

References

  1. 1 2 3 4 5 Holers 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.
  2. ↑ Verschoor A, Kemper C, Köhl J (15 September 2017). "Complement Receptors". Encyclopedia of Life Sciences. pp. 1–17. doi:10.1002/9780470015902.a0000512.pub3. ISBN   9780470015902.
  3. ↑ Carroll MC (December 2008). "Complement and humoral immunity". Vaccine. 26 (Suppl 8): I28-33. doi:10.1016/j.vaccine.2008.11.022. PMC   4018718 . PMID   19388161.
  4. 1 2 3 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.
  5. ↑ Parham P (2005). The Immune System (2nd ed.). Garland Science. ISBN   9780815340935.
  6. ↑ Schwartz RA, Thomas I. "Complement Receptor Deficiency: eMedicine Dermatology". Medscape. Retrieved 7 December 2010.
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