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Complement C3Complement C4Complement C4aComplement C3aComplement C1qComplement C5aComplement ActivationComplement C4bComplement C5Complement C3bComplement System ProteinsComplement C6Complement C3cComplement C3dComplement C2Complement C9Receptors, ComplementComplement C1sComplement Membrane Attack ComplexComplement C1rComplement Inactivator ProteinsComplement C7Complement C3-C5 ConvertasesComplement Factor BComplement Pathway, AlternativeComplement Pathway, ClassicalComplement C8Complement C1Receptors, Complement 3bComplement Factor HComplement C5bComplement C2aReceptor, Anaphylatoxin C5aComplement Activating EnzymesComplement Inactivating AgentsComplement Hemolytic Activity AssayComplement C1 Inactivator ProteinsReceptors, Complement 3dAnaphylatoxinsComplement Fixation TestsComplement Factor DComplement Factor IComplement C4b-Binding ProteinComplement C3b Inactivator ProteinsAntigens, CD55Complement C3-C5 Convertases, Classical PathwayComplement C2bAntigens, CD59Cobra VenomsAntigen-Antibody ComplexSteroid 21-HydroxylaseComplement C3-C5 Convertases, Alternative PathwayComplement C1 Inhibitor ProteinImmunoglobulin GHemolysisComplement C3 Convertase, Alternative PathwayComplement C5 Convertase, Classical PathwayMolecular Sequence DataComplement C3 Convertase, Classical PathwayAntigens, CD46Opsonin ProteinsBlood ProteinsLupus Erythematosus, SystemicComplement C5 Convertase, Alternative PathwayPhagocytosisAmino Acid SequenceComplement Pathway, Mannose-Binding LectinProperdinComplement C5a, des-ArginineMice, Inbred C57BLMacrophage-1 AntigenProtein BindingNeutrophilsBase SequenceKidney GlomerulusSerumGlomerulonephritis, MembranoproliferativeImmunoglobulin MSchistosomaGenetic Complementation TestEnzyme-Linked Immunosorbent AssayMice, KnockoutGlomerulonephritisArteriolosclerosisAntibodies, MonoclonalMajor Histocompatibility ComplexErythrocytesAutoantibodiesCells, CulturedRNA, MessengerMacrophagesCell LineImmunity, InnatePeptide FragmentsMutationRabbitsDisease Models, AnimalCloning, MolecularMice, Inbred BALB CBinding Sites
PathwaysBindsCleavageCleavesHeat-labile componentLectin pathwayRelated to the complement systemProteinsDegradationSerinePathway of complement activationCascadeActivationConvertaseMolecularMacular degenerationBacteriaMoleculesPhagocytosisRegulatorAntigenMacrophageRegulatoryBindSystemImmuneSerumDeficiencyInflammationResistanceErythrocytesActivityAntibodiesFactorComponentHumanComponentsCellsSurface
Pathways13
  • Activation of the complement system in response to an infection or foreign antigen is achieved via three complement pathways, the classical pathway, which is activated by antigen-antibody complexes, the lectin pathway, which is activated by the interaction of microbial carbohydrates with mannose-binding proteins in the plasma and tissue fluids, and the alternative complement pathway, which is activated by C3b binding to microbial surfaces and to antibody molecules. (hindawi.com)
  • There are three pathways of activation, each of which leads to the formation of C3a and C3b, which is involved in antigen opsonization. (wikipedia.org)
  • Learn about the three pathways lead to complement activation and some of their key inhibitors. (abcam.com)
  • the classical pathway initiated by antibodies bound to the surface of foreign bodies and the alternative and lectin pathways that provide an antibody-independent mechanism for complement activation, induced by the presence of bacteria and other micro-organisms. (abcam.com)
  • Three activating pathways comprise the complement cascade (classical, mannose-binding lectin, and alternative), and all converge on the proteolytic cleavage of C3 to generate an arsenal of inflammatory mediators, including the opsonin C3b and the anaphylatoxin C3a. (molvis.org)
  • Its processing by C3 convertase is the central reaction in both classical and alternative complement pathways. (abcam.com)
  • Several complement inhibitors targeting various complement pathways are in clinical trials for the treatment of HSCT-TMA. (biomedcentral.com)
  • Three biochemical pathways activate the complement system: the classical complement pathway , the alternative complement pathway , and the mannose-binding lectin pathway . (wikidoc.org)
  • The classical complement pathway typically requires antibodies for activation (specific immune response), while the alternative and mannose-binding lectin pathways can be activated by C3 hydrolysis or antigens without the presence of antibodies (non-specific immune response). (wikidoc.org)
  • In all three pathways, a C3-convertase cleaves and activates component C3 , creating C3a and C3b and causing a cascade of further cleavage and activation events. (wikidoc.org)
  • The classical and alternative complement pathways. (wikidoc.org)
  • Both bacterial species carry lipooligosaccharides preventing complement attacks and attract and utilize host complement regulators C4b binding protein and factor H to inhibit the classical and alternative pathways of complement activation, respectively. (bvsalud.org)
  • The complement pathways are also a part of the defensive measures of the innate immune system. (brmi.online)
Binds7
  • Complement C3b is the major opsonin of the complement system which facilitates the phagocytosis process by coating antigens (each of the phagocytes expresses a complement receptor such as CR1, CR3, or CR4 that binds C3b, C4b, or C3bi) [ 28 , 29 ]. (hindawi.com)
  • This complex has the ability to catalyze the formation of C3a and C3b after it binds properdin, a globulin protein, and is stabilized. (wikipedia.org)
  • If left to propagate, the accumulation of C3b triggers cleavage of C5 to produce C5a and C5b, with the latter inducing the assembly of a membrane attack complex (MAC) that binds to cell surfaces, forming transmembrane channels that cause cytolysis or apoptosis of the target cells. (molvis.org)
  • Upon activation and cleavage of C3, C3b is formed as a major fragment that covalently binds to its target (see Table 1). (medscape.com)
  • Trouw L., Nilsson S., Goncalvez I., Landberg G. and Blom A. M. (2005) C4b-binding protein binds to necrotic cells and DNA, which limits DNA release and inhibits complement activation. (lu.se)
  • C3b binds to the surface of pathogens leading to greater internalization by phagocytic cells by opsonization . (wikidoc.org)
  • An array of different outer membrane proteins (OMP) in H. influenzae and M. catarrhalis simultaneously binds complement regulators, but also plasminogen. (bvsalud.org)
Cleavage4
  • Factor I-mediated cleavage of the α chain of C3b liberates 3 fragments with molecular weights of 68 kDa, 43 kDa, and 2 kDa. (hindawi.com)
  • C3a formation occurs through activation and cleavage of complement component 3 in a reaction catalyzed by C3-convertase. (wikipedia.org)
  • Following these cleavage events, complement pathway activation continues as in the classical pathway. (abcam.com)
  • The current dogma of CFH function is to downregulate the complement cascade, by inhibiting cleavage of C3, limiting the generation of byproducts that spur inflammation. (molvis.org)
Cleaves3
  • Factor I cleaves C3b and C4b in a reaction, where fI is dependent on various cofactors, such as factor H, C4b-binding protein CR1 and membrane cofactor protein (MCP) [ 26 ]. (hindawi.com)
  • C2a in the convertase complex cleaves C3 releasing C3a and C3b. (abcam.com)
  • mouse homolog is a regulatory serine proteinase of the complement cascade that cleaves C3b and C4b and inactivates them [RGD, Feb 2006]. (genscript.com)
Heat-labile component3
  • The complement system is a heat-labile component of blood that confers bactericidal properties. (abcam.com)
  • The heat-stable component was found to confer immunity against specific microorganisms, while the heat-labile component was found to be responsible for the non-specific antimicrobial activity conferred by all normal serum. (wikidoc.org)
  • Ehrlich therefore named this heat-labile component "complement", because it is something in the blood which "complements" the cells of the immune system. (wikidoc.org)
Lectin pathway5
  • Mannan-binding lectin (MBL) and MBL-associated serine proteases (MASPs) are involved in the initial step of the lectin pathway of complement activation. (abcam.com)
  • In particular, the lectin pathway of complement is activated by damage-associated molecular patterns (DAMPs) on the surface of injured endothelial cells. (biomedcentral.com)
  • In this article, we review the role of the complement system in HSCT-TMA pathogenesis, with a focus on the lectin pathway. (biomedcentral.com)
  • Endothelial injury triggers activation of the complement system-significantly through the lectin pathway-via altered cell-surface patterns on injured endothelial cells, initiating an inflammatory response [ 7 ]. (biomedcentral.com)
  • Here we discuss evidence for the role of lectin pathway activation in endothelial injury-associated complications of HSCT and how targeting complement activity may provide therapeutic benefit for patients with HSCT-TMA. (biomedcentral.com)
Related to the complement system1
  • It has been shown by comparison with healthy control children that several differentially expressed proteins are related to the complement system in children with ASD [ 22 ]. (hindawi.com)
Proteins5
  • The complement system comprises a group of proteins which, when activated, provide one of the first lines of defence by promoting lysis and the removal of invading microbes. (hindawi.com)
  • The complement system consists of a number of small proteins found in the blood, normally circulating as inactive zymogens . (wikidoc.org)
  • Over 20 proteins and protein fragments make up the complement system, including serum proteins, serosal proteins, and cell membrane receptors. (wikidoc.org)
  • Host defense against bacterial invasion depends on phagocytosis by polymorphonuclear granulocytes and the bactericidal effect of serum, mediated in large part by complement proteins. (medscape.com)
  • Several of the bacterial complement-binding proteins are important adhesins and contain highly conserved regions for interactions with the host. (bvsalud.org)
Degradation4
  • Complement factor I is a serine protease present in human plasma that is involved in the degradation of complement protein C3b, which is a major opsonin of the complement system. (hindawi.com)
  • Degradation of C3b by fI abrogates the action of this protein in the C3 pathway [ 27 ]. (hindawi.com)
  • Derived from proteolytic degradation of complement C3, C3a anaphylatoxin is a mediator of local inflammatory process. (abcam.com)
  • FHL-1 with their areas and promoting aspect I-mediated C3b degradation. (eotp.org)
Serine3
  • The plasma glycoprotein factor I (C3b/C4b inactivator) is a serine protease that acts as a regulator of the complement C3 cascade. (hindawi.com)
  • The classical pathway of complement activation is initiated when the C1 complex, made up of C1r and C1s serine proteases, recognizes the Fc region of IgM or IgG antibodies bound to a pathogen. (wikipedia.org)
  • This activation induces a conformational change in the thioester domain of C3(H2O) that allows it to bind to a plasma protein called Factor B. This complex is then cleaved by Factor D, a serine protease, to form C3b(H2O)Bb, or fluid-phase C3-convertase. (wikipedia.org)
Pathway of complement activation3
  • The alternative pathway of complement activation is typically always active at low levels in blood plasma through a process called tick-over, in which C3 spontaneously hydrolyzes into its active form, C3(H2O). (wikipedia.org)
  • The alternative pathway of complement activation is in a constant state of low-level activation (known as tickover). (abcam.com)
  • In addition, the regulator of the terminal pathway of complement activation, vitronectin, is hijacked by both bacteria. (bvsalud.org)
Cascade5
  • C1 is the first molecule in the classical complement cascade and comprises C1q and two molecules of C1r and C1s respectively. (abcam.com)
  • Dysregulation of the complement cascade contributes to a variety of retinal dystrophies, including age-related macular degeneration (AMD). (molvis.org)
  • The activation of an immune cascade known as the complement system is a crucial factor in the etiology of age-related macular degeneration (AMD). (molvis.org)
  • Together, activation of complement and the coagulation cascade lead to a procoagulant state that may result in development of HSCT-TMA. (biomedcentral.com)
  • The complement system is a biochemical cascade which helps clear pathogens from an organism. (wikidoc.org)
Activation10
  • C3a is an effector of the complement system with a range of functions including T cell activation and survival, angiogenesis stimulation, chemotaxis, mast cell degranulation, and macrophage activation. (wikipedia.org)
  • These data improve our understanding of the impact of C3 inhibition in subretinal inflammation and inform the development of treatments for targeting complement activation in diseases such as AMD. (molvis.org)
  • This feature prioritizes modifiers of C3 activation as potential therapeutics for ameliorating complement [ 5 ], although additional molecular studies are required to develop the groundwork needed for effective targeting of complement. (molvis.org)
  • C3 plays a central role in the activation of the complement system. (abcam.com)
  • After activation C3b can bind covalently, via its reactive thioester, to cell surface carbohydrates or immune aggregates. (abcam.com)
  • The induced IgG and IgM antibodies were able to stimulate various Fc-mediated effector mechanisms associated with protection against malaria, including phagocytosis, release of reactive oxygen species, production of IFN-γ as well as complement activation and fixation. (nature.com)
  • Endothelial injury can trigger activation of the complement system, promoting inflammation and the development of endothelial injury syndromes, ultimately leading to organ damage and failure. (biomedcentral.com)
  • Sjöberg A., Trouw L., McGrath F., Hack E. C. and Blom A. M. (2006) Regulation of complement activation by C-reactive protein: targeting of the inhibitory activity of C4b-binding protein. (lu.se)
  • Both classic-pathway and alternate-pathway complement activation have been described, but the latter, which does not require the presence of immunoglobulins directed against bacterial antigens, appears to be the more active pathway in K pneumoniae infections. (medscape.com)
  • This is accomplished mainly by inhibiting the activation or uptake of complement components, especially C3b. (medscape.com)
Convertase1
  • it was reported that glycoprotein c of hsv-1 (gc-1) mediates the binding of c3b-coated erythrocytes to infected cells and has regulatory (decay-accelerating) activity for the alternative pathway c3 convertase of human complement. (liverpool.ac.uk)
Molecular1
  • Mark L., Lee W. H., Villoutreix B. O., Proctor D., Blackbourn, D., Spiller B. O. and Blom A. M. (2004) KSHV complement control protein mimics human molecular mechanisms for inhibition of the complement system. (lu.se)
Macular degeneration2
Bacteria1
Molecules1
  • They are able to activate complement, which causes selective deposition of C3b onto LPS molecules at sites distant from the bacterial cell membrane. (medscape.com)
Phagocytosis1
  • The functions of complement include the attraction of inflammatory cells, opsonization to promote phagocytosis, immune complex clearance and direct microbial killing through the formation of the membrane attack complex (MAC). (abcam.com)
Regulator1
  • Spiller B. O., Blackbourne, D., Mark L, Proctor D. and * Blom A. M. , (2003) Functional activity of the complement regulator encoded by Kaposi's sarcoma associated herpesvirus. (lu.se)
Antigen1
  • Ehrlich believed that each antigen-specific amboceptor had its own specific complement, while Bordet believed that there is only one type of complement. (wikidoc.org)
Macrophage1
  • Kupffer cells and other macrophage cell types help clear complement-coated pathogens. (wikidoc.org)
Regulatory3
  • C3a has a regulatory process and a structure homologous to complement component C5a, with which it shares 36% of its sequence identity. (wikipedia.org)
  • Blom, A. M. , Rytkönen, A., Vasquez, P., Dahlbäck, B. and Johnsson, A-B. (2001) A novel interaction between type IV pili of Neisseria gonorrhoeae and complement regulatory protein - C4b-binding protein. (lu.se)
  • Blom A. M. , Kask L. and B. Dahlbäck (2001) Structural requirements for the complement regulatory activities of C4b-binding protein. (lu.se)
Bind2
  • C3b and C4b bind to CR1, which is present on various phagocytes and also on erythrocytes and B cells. (medscape.com)
  • herpes simplex virus glycoproteins gc-1 and gc-2 bind to the third component of complement and provide protection against complement-mediated neutralization of viral infectivity. (liverpool.ac.uk)
System3
  • Immune system abnormalities may be caused partly by complement system factor I deficiency. (hindawi.com)
  • The complement system exerts many of its effects through complement receptors (CRs). (medscape.com)
  • The term "complement" was introduced by Paul Ehrlich in the late 1890s, as part of his larger theory of the immune system. (wikidoc.org)
Immune1
  • Factor I deficiency can be conferred by a C3 deficiency, since this also increases susceptibility to pyogenic infections by Neisseria meningitides, Haemophilus influenza, and Streptococcus pneumonia and increases the incidence of immune complex diseases due to impaired complement-mediated function [ 30 ]. (hindawi.com)
Serum2
  • Ail confers serum resistance in humans and is a critical virulence factor of Y. pestis, the causative agent of plague. (cdc.gov)
  • Among identified virulence factors is the attachment invasion locus protein, Ail, that is required to protect Y. pestis from serum complement in all mammals tested except mice. (cdc.gov)
Deficiency1
  • Of the 8 plasma membrane receptors for complement, only deficiencies of CR3 and CR4 due to CD18 deficiency have been described, known as leukocyte adhesion deficiency (LAD) type 1 . (medscape.com)
Inflammation1
  • Sjöberg A., Önnerfjord, P., Mörgelin, M., Heinegård, D. and Blom A. M. (2005) Extracellular matrix and inflammation: fibromodulin activates the classical pathway of complement by directly binding C1q. (lu.se)
Resistance1
  • Caucasica 1146 conferred resistance to human complement when expressed in the Y. pestis KIM6(+) ail mutant. (cdc.gov)
Erythrocytes1
  • cells infected with herpes simplex virus type 1 (hsv-1) form rosettes with c3b-coated erythrocytes, whereas cells infected with herpes simplex virus type 2 (hsv-2) or other herpes viruses do not. (liverpool.ac.uk)
Activity2
  • In this paper, we show that the mean level of factor I activity in the ASD group is significantly higher than in the control group of typically developed and healthy children, suggesting that high activity of complement factor I might have an impact on the development of ASD. (hindawi.com)
  • Yersinia pestis Δail Mutants Are Not Susceptible to Human Complement Bactericidal Activity in the Flea. (cdc.gov)
Antibodies1
  • In the early 20th century, this controversy was resolved when it was understood that complement can act in combination with specific antibodies, or on its own in a non-specific way. (wikidoc.org)
Factor1
Component1
  • The central component of complement, C3, is expressed in abundance by macrophages in the outer retina, and its ablation suppresses photoreceptor death in experimental photo-oxidative damage. (molvis.org)
Human1
  • The human respiratory pathogens Haemophilus influenzae and Moraxella catarrhalis are no exceptions and have developed sophisticated mechanisms to evade complement-mediated killing. (bvsalud.org)
Components2
  • Complement components deposited rapidly on the Y. pestis surface as measured by immunofluorescent microscopy. (cdc.gov)
  • Transcriptome characterization by RNA-Seq reveals the involvement of the complement components in noise-traumatized rat cochleae. (genscript.com)
Cells1
  • This recommended that T lymphocytes had been mixed up in general control of tumor advancement, but that NK cells had been necessary for the added safety conferred by disease. (eotp.org)
Surface1
  • Ail reduced the amount of active C3b on the Y. pestis surface. (cdc.gov)