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29 Cards in this Set
- Front
- Back
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2 specific functions of complement system
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lysis
opsonization of Ag |
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C3a/C5a mediate?
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inflammation
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C5-C9 form?
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membrane attack complex
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C3b does what?
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opsonin
orange marmalade! |
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Classical pathway deficiency causes?
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Immune complex dx
Pyogenic infections |
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Alternative pathway deficiency causes?
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Pyogenic infections
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MBL pathway deficiency causes?
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Pyogenic infections in neonates & children
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Membrane attack complex deficiencies cause?
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Neisseria infections, especially meningococcal dx
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What is the most abundant complement protein
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C3
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What acitvates each of the 3 complement pathways
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Classical--> Ab:Ag complex
MBL--> microbial polysaccharides Alternative-->LPS/foreign surfaces (like glass, catheter) Alternative--> |
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Which compliment fragments bind covalently to the microbial surface?
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C4b & C3b
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C4b & C3b bind to the microbial surface by what bond?
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Thioester
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What function does C4b & C3b binding to the microbial surface serve?
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Opsonization/tagging for destruction
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C1 binds to what on an antigen?
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Two IgGs or one IgM.
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When the C1qr2s2 complex binds the ab:ag complex, what happens next?
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Conformational change-->C4 cleavage
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What does C1INH do?
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Inhibits C1 actions, preventing opsonization by C4 on healthy cells
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What is the end result of the C1-C4 cascade?
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Amplification 10000x
Permanent tagging for destruction |
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MBL is the equivalent of what other complement cascade molecule?
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C1q (Classical pathway)
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How is the alternative pathway activated?
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Spontaneous hydrolysis of C3
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What molecule stabilizes C3 in the alternative pathway
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Properdin (C3bBb)
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What antigenic surfaces best activate the alternative pathway?
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Surfaces rich in carbohydrate and deficient in sialic acid
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What feature is presented on human cells that prevent tagging of self-cells by C3?
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Sialic acid
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C5a is what kind of molecule?
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Anaphylotoxin
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What control method prevents the C5b67 complex from inserting into a cell membrane?
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S-protein
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How is C3 'tickover' controlled?
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Factor H i/h C3 convertase. It can bind free C3bBb, causing decay acceleration.
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How does sialic acid contribute to protecting host cells?
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Sialic acid allows binding of Factor H to the cell membrane where it can displace/inactivate the C3bBb complex
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C1 deficiency causes?
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hereditary angioedema
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DAF (decay acceleration factor, CD55) & CD59 deficiency causes?
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RBC MAC-mediated lysis (hemolysis)
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CR1 on RBCs performs what important function?
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Transports ICs to the liver
Blocks C3 convertase formation |
