9 B Cell Mediated Immunity II: Complement Cascade Flashcards

1
Q

Where are complement proteins made?

A

Liver

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2
Q

What is the main goal of complement?

A

Permanent tagging

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3
Q

What three pathways does the complement system have?

A

Lectin
Alternative
Classical

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4
Q

What is the Lectin pathway?

A

MBP
MASP 1 and 2
C4 and C2 cleavage to C3 convertase
same as classical and alternative from here

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5
Q

What is the Alternative pathway?

A

C1 binds the Fc region of an antibody
C1qrs is cleaved, rs activates C4 and C2
C3 convertase is formed
C3b binds to surface to opsonize

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6
Q

What is the Classical pathway?

A

Basically a positive feedback system
C3b binds
Factor B
Factor D
C3Bb forms to make alternative C3 convertase
other C3bs are created, and C3Bb3b forms to increase positive feedback loop

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7
Q

What phagocyte receptor recognizes the C3b on the surface of a pathogen?

A

CR1 of phagocytes

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8
Q

What is CR2 and why is it clinically important?

A

Epstein Barr Virus infected cells use this coreceptor as a gateway to the B cell

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9
Q

What opsonizing proteins are recognized by CR2?

A

C3d
C3dg
iC3b
Epstein Barr virus

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10
Q

What is a CR2 receptor and where is it located?

A

Synergistic Coreceptor for B cells, FDCs

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11
Q

What complement receptors can act on their own to initiate phagocytosis? By binding what?

A

CR3
CR4
by binding iC3b

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12
Q

How are complement reactive complexes mainly eliminated?

A

Via the RBC CR1 receptor binding to C3b or C4b, taking this to the splenic macrophages for engulfment.

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13
Q

If a complement complex gets to the kidney, what removes them from the glomerulus?

A

Podocytes

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14
Q

What disease is caused by a overflow of complement complexes due to autoimmune reactions?

A

Systemic Lupus Erythmatosis (SLE)

this can cause kidney failure and chronic inflammation

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15
Q

What proteins form the Membrane Attack Complex?

A

C5b, 6,7,8,9

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16
Q

What is the classical C5 Convertase?

A

C4b,C2a, 3b

17
Q

What is the alternative C5 convertase?

A

C3b2, Bb

18
Q

What does a lack of the MAC leave us vulnerable to?

A

Neisseria Species infections

19
Q

What does a lack of C5a lead to?

A

Lessened Neutrophil chemotaxis,

Leiner disease in infants

20
Q

What are the main chemoattractants?

A

C3a
C4a
C5a
(the parts of the complement that do not get used in C3 or C5 convertase)

21
Q

What is the most powerful chemotractant?

A

C5a

22
Q

What does C5a induce?

A

Neutrophil and Macrophage chemotaxis

C1 and C3 production in liver

23
Q

What two main locations do complement regulatory proteins reside?

A

Plasma

Cell Surface

24
Q

What are the plasma regulator proteins?

A

C1 Inhibitor (C1INH)
C4 Binding Protein (C4BP)
Factor H
Factor I

25
Q

What are the cell surface complement regulatory proteins?

A

Decay Accelerating Factor (DAF)
Membrane Co-factor Protein (MCP)
Complement Receptor 1 (CR1)
CD59

26
Q

What complement protein do almost all regulatory proteins attach to?

A

C3b and C4b

these are the most crucial hubs

27
Q

What complement proteins do the non-c3b or c4b binding regulatory binding proteins bind to?

A

The complement protein in their name!

C1INH, C4BP, CD59

28
Q

What is the regulatory protein for the MAC?

A

CD59

binds to C5b,6,7,8 complex for factor I

29
Q

What complement regulatory proteins bind complement for factor I action?

A

C4BP
Factor H
MCP
CR1

30
Q

What disease is due to a defect in CD59 or DAG?

A

Paroxymal Nocturnal Hemoglobinuria

31
Q

What disease is due to a defect in C1INH?

A

Heriditary Angioneurotic Edema (HANE)

pts have big lips and swollen faces

32
Q

What chemotractants bring in mast cells?

A

C3a

C5a

33
Q

What complement pathway is reliant on B cells to work?

A

Classical

34
Q

What antibody pathway is the first to work?

A

Alternative and Lectin

35
Q

What were the diseases we discussed from the complement system?

A
Lupus
HANE
Paroxymal nocturnal hemoglobinuria
Neisseria infections
Epstein Barr Virus gateway