Regulators and receptors of the complement system
- M Kathryn Liszewski, PhD
M Kathryn Liszewski, PhD
- Assistant Professor of Medicine
- Washington University School of Medicine
- John P Atkinson, MD
John P Atkinson, MD
- Samuel B Grant Professor of Medicine
- Professor of Molecular Microbiology
- Chief, Division Rheumatology
- Washington University School of Medicine
- Section Editors
- E Richard Stiehm, MD
E Richard Stiehm, MD
- Editor-in-Chief — Allergy and Immunology
- Section Editor — Immunology and Immunodeficiency
- Distinguished Research Professor of Pediatrics
- David Geffen School of Medicine at UCLA
- Peter H Schur, MD
Peter H Schur, MD
- Editor-in-Chief — Rheumatology
- Section Editor — Basic Science
- Professor of Medicine
- Harvard Medical School
Precise control of the complement system is necessary because of its potent proinflammatory and cellular destructive capabilities. The regulation of the complement system will be reviewed here. In order to fully comprehend the functions of the various regulatory proteins, it is helpful to be familiar with the complement pathways, which are reviewed elsewhere. (See "Complement pathways".)
Nearly one-half of all complement proteins serve a regulatory function [1-4]. The goal of regulation is to prevent complement damage to normal host tissue (inappropriate or wrong target) and fluid-phase activation (no target) . Deficiencies of control proteins lead to excessive complement activation and significant morbidity and mortality. (See "Inherited disorders of the complement system".)
Regulatory proteins inhibit the system by destabilizing activation complexes and by mediating specific proteolysis of activation-derived fragments. The complement pathways are regulated at the following critical steps:
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- COMPLEMENT REGULATION
- Control of activation/initiation
- Control of amplification
- Control of membrane attack
- Control of anaphylatoxins
- COMPLEMENT RECEPTORS
- Complement receptor 1
- Complement receptor 2
- Complement receptor 3
- Complement receptor 4
- Complement receptor of the immunoglobulin superfamily
- Receptors for C5a and C3a
- - C5a receptor
- - C3a receptor
- Other receptors