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36 Cards in this Set
- Front
- Back
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Synthesis of complement proteins occurs in what type of cells?
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Hepatocytes
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Several of the genes for complement componenets are found within the ?
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MHC
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Activation of complement requires what two elements?
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Ca2+
Mg2+ |
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What is the key step in complement activation?
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cleavage of C3 into C3a and C3b
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List the Alternative Pathway
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self hydrolysis of C3
=> iC3 -> binds to factor B => Factor D cleaves factor B => iC3Bb (C3 convertase) => C3b |
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What are the two C3 convertases for the Alternative Pathway?
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C3bBb
iC3Bb |
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How is C5 convertase made in the Alternative pathway?
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C3bBb + C3b
=> C3b(2)Bb |
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What stabilizes C3bBb on microbial surfaces and preventing actions of Factors H and I?
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Properdin (Factor P)
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What in the alternative pathway is used to bind to C3b and make it susceptible to cleavage by ?
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FACTOR H binds to C3b
promotes cleavage of C3b by FACTOR I |
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A lack of Factor I will cause a depletion of what complement protein?
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C3
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What binds to C3b part of convertases and causes dissociation and inactivation?
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DAF
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What binds to C3b part of convertase, causes dissociation and inactivation, and more susceptible to cleavage and inactivation by FACTOR I?
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MCP
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What binds to C3b part of convertase, cause dissociation and inactivation, binding to sialic acid which is present on human cells but absent from most bacteria?
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Factor H
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List the order of Complement pathways?
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Alternative pathway
Lectin pathway Classical Pathway |
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What triggers the Lectin Pathway?
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Inflammation
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Describe the Lectin Pathway
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MBL binds to mannose on microorganisms
=> MASP binds to MBL =>MASP cleaves C4 then C2 => C4b2a (C3 Convertase) cleaves C3 => C4b2a3b (C5 convertase) |
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What is the C3 convertase of the Lectin Pathway?
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C4b2a
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What is the C5 convertase of the Lectin Pathway?
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C4b2a3b
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How is the Classical Pathway of complement started?
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antibody binds to target
OR C-reactive Protein (CRP) |
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What is are the two Ab that can activate Classical Pathway?
Which one works best? |
IgM (pentamer <--- best)
IgG |
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Describe the Classical Pathway of Complement.
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Ab + Ag bind // CRP
=> C1q binds to Fc region => self activation of C1r >> cleavage forms C1s => C1s cleaves C4 => C4b ---> merges with lectin pathway => C4b2a3b |
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In the Classical / Lectin Pathway, C1-Inh binds to C1 causing the release of?
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C2b
Vasoactive substance |
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What binds to C4b2a displaces C2a and increases sensitivity of C4b to FACTOR I
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C4bp
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What functions as C4bp on the surface of cells (causes C4b to be sensitive to Factor I) in the classical / lectin pathway
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CR1 and MCP
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What dissociates C4b2a in the classical / lectin pathway?
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DAF
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What is the C5 convertase of classical / lectin pathway?
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C4b2a3b
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What is the structure that inserts itself into the membrane?
What causes the pore formation in the membrane? |
C5b67
C5b678 + C9 |
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name the control proteins that prevent C5b67 from associating with cell membranes (3)
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S protein
Clusterin Factor J |
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What proteins prevent recruitment of C9?
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HRF (homologous restriction factor)
PROTECTIN CD59 |
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Complement is an important effector of the ? immune response.
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Humoral
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What parts of the complement proteins are important in activation of inflammation?
they are known as? |
C3a
C5a ANAPHYLOTOXINS |
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What cells have receptors for C3a and C5a?
What is released when they bind? |
Mast cells
Basophils Histamine |
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What cell helps clear C3b from the system?
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Erythrocytse
=> travel to spleen |
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Hereditary angioedema is seen in patients with?
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Deficiency in C1 - INH
causing excess C2b <--vasoactive |
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Paroxymal Nocturnal Hemoglobinurea is seen in patients that have a defect in what?
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DAF (CD55)
HRF CD59 causes blood cells to be more sensitive to complement |
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What are the consequences of complement pathway?
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cell lysis
opsinization inflammation clearance of immune complexes |
