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31 Cards in this Set
- Front
- Back
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Definition of Complement
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Biochemical cascade of immune system.
found in all vertebrates. helps clear pathogens |
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Complements 3 Areas it has roles in
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Innate Immunity.
Disposal System. Adaptive Immunity. |
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3 Ways to Activate Complement
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Classical.
Alternative. Mannose Binging Lectin. |
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Shared Pathway after activation
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Common Pathway (Lytic Pathway) - Leads to Membrane Attack Complex.
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Roles of Fragments in complement
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Opsonins.
Chemotactics. Immune Response Stimulating. |
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Classical Activation is:
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Activation by antibodies.
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Which Antibodies Activate Complement?
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IgM is best.
IgG1 and IgG3 second best. Rest of IgG's IgE and IgA are pretty rubbish |
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How do antibodies activate complement?
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Bind to C1q -> Causing C1s to activate C2 + C4
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C1 is made up of
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C1q + C1r + C1s
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C1q is a
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6 headed large molecule - made up of collagen stalks
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C2bC4b =
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Activated C2 and C4 (C3 Convertase)
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Central Molecule in Complement is
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C3
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C3 is
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Abundant.
Stable when one molecule. |
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C3 roles
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Supports local inflammation.
Instructs adaptive immune response. |
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C3 is activated by
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C2bC4b.
Also other cascades - Coagulation + Fibrinolytic |
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Terminal/Lytic Pathway is to
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Form Membrane Attack Complexes
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C3 Activates
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C5 -> C5a + C5b
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C5b's role
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Combine and Activate C6 + C7
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Membrane Attack Complex is a combination of:
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C5b 6 7 89
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MAC is to
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Form Pores in Cell Membrane.
Allowing insertion of enzymes for cell death. |
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Mannose Binding Lectin Pathway is:
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Activation by MBL - bound to repetitive unists of sugars on microbes.
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Why repetitive units of sugars?
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As present on microbes but not mammalian membranes.
Repetitive as limited genome |
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What binds to MBL?
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MASP 1 + MASP 2.
- Similar Structure to C1s + C1r |
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Alternative Pathway is:
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Spontaneous low level breakdown of C3.
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Alternative Pathway doesn't happen on mammalian cells as -
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They have inhibitory proteins - CD35 +CD59
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In alternative pathway C3b binds to
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Factor B - To form C3b.B
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Factor D changes C3b.B into
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C3b.Bb (D has activated B)
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Properdin binds to C3b.Bb ->
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C3b.Bb.P
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C3b.Bb.P is a form of:
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C3 Convertase
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C3b binds to C3b.Bb.P ->
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C3b.Bb.P.C3b
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C3b.Bb.P.C3b is a form of:
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C5 Convertase.
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