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34 Cards in this Set
- Front
- Back
the complement system is the major effector of the....
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humoral branch of the immune system
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RBC + serum>
RBC + Ab> RBC + serum + Ab> |
ok
ok lysed |
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is complement a single protein?
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no it is 12 proteins
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does complement affect innate or adaptive?
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both
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4 functions of complement
p |
-lysis
-opsonization -activatione of inflammatory response -clearance of immune complexes see page 169 |
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complement makes up what fraction of serum globulin?
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5%
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what is complement designated by?
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numerals (C1-C9)
letter symbols (factor D) trivial names (homologous restriction factor) |
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talk about the a and b fragment
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the b fragment is always larger....except in the case of C2
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ccomplexes with enzymatic activity are designated by what over the symbol?
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a bar will be over the symbol
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3 basic pathways complement can be activated in....don't describe
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-classical
-alternative -lectin |
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Descibe the classical pathway
p. 170 and 172 |
170-172
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how are C1-4 found in the plasma normally?
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they are present in the plasma in functionally inactive forms
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C1 structure, and interaction, and random tidbits
p. 170-171 |
C1qr2s2....it is a macromolecule with a molecule of q, 2 molecules of r and 2 molecules of s
-Structure is stabilized by calcium ion -Each c1r and c1s monomer contains a catalytic domain with enzymatic activity and an interaction domain that facilitates binding with C1q or with each other |
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IgM bound to membrane antigen vs serum antigen and binding to C1
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-membrane antigen will cause IgM to have stable conformation and will have 3 binding sites for C1
-circulating IgM, however, will be planar and there will be no C1q binding site |
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IgG activating classical complement pathway
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It only has 1 binding site (remember IgM has 3)...and because of this, 2 molecules must be 30-40nm apart from each other on a target surface or in a complex
-a single molecule of igM bound to a rbc can activate complement system, but 1000 or more IgG molecules are needed to ensure that 2 molecules are close enough for to initiate c1q binding. |
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how does C4b2a bind to bind?
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adjacent to antibody
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anaphylatoxins for chemotaxis
Inflammation! |
C3a- C5a
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opsonization for uptake by
phagocytic cells |
C3b, iC3b
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Membrane attack complex (M.A.C.)
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C5b-C9
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biological consequences of complement activation
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-opsonization for uptake by phagocytic cells
-anaphylatoxins for chemotaxis inflammation -Membrane attack complex (MAC) |
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whats type of complement to phagocytic cells have receptors for?
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C3
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alternative pathway involves what four serum proteins?
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c3, factor b, factor d and properdin
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in most cases how is the alternative pathway initiated?
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by cell surface constituents that are foreign to the host
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what are some initiaters of alternative pathway complement activation?
p. 173 |
page 173
.....don't need to know all |
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talk about c3 in alternative pathway
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c3 in serum has an unstable thioester bond: subject to slow spontaneous hydrolysis to yield C3a and C3b....c3b component can bind to foreign surface antigens....bacterial cells or viral particles
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diagram the alternative pathway
p. 174 |
p. 174
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what do the membranes of most mammalian cells have?
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sialic acid: contributes to the rapid inactivation of bound C3b molecules on host cells: foreign cells do not have as much
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what does serum c3 contain?
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unstable thioester bonds....this leads it to spontaneous hydrolysis
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what does the MAC eventually do?
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forms a large channel through the membrane of the target cell, enabling ions and small molecules to diffuse freely across the membrane
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what is the end result of the classical, alternative or lectin pathway?
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production of an active C5 convertase
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when does the complement cascade go from being on the hydrophillic surface of membranes or immune complexes to creating exposure for hydrophobic regions that will bind to membrane phospholipids?
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as c5b6 binds to C7.....the hydrophobic binding sites allow it to anchor to the cell
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what is the amplification step in all pathways
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when c3 convertase converts c3 into c3a and c3b
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talk about the MAC
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-C5b6789
-initial C5b678 creates a 10A diameter pore....can lead to lysis of RBC's but not of nucleated cells -final step is formation of the MAC is the binding and polymerization of C9, a perforin-like molecule, to the C5b678 complex...now has pore of 70-100A p.178 |
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wht are regulatory mechanisms necessary for complement
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because elements of complement are capable of attacking host cells as well as foreign cells and microorganisms
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