Lecture 13: Effector Mechanisms of Humoral Immunity Flashcards

1
Q

functions of antibodies against microbes and their toxins

A
  • Neutralize these agents
  • Opsonize them for phagocytosis
  • Sensitize them for Ab-dependent cellular cytotoxicity
  • activate the complement system
  • (note that the various functions are mediated by different Ab isotypes)
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2
Q
A
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3
Q

The influenza viruses use their envelope _______ to infect respiratory epithelial cells

A

Hemagglutinin

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4
Q

What are virulence factors

A
  • refer to the properties of bacterial gene products that enable a microorganism to cause disease
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5
Q
A
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6
Q

Isotypes ____ and ___ are the most efficient opsonins for promoting phagocytosis via high-affinity FcgammaRI (CD64)

A
  • IgG1
  • IgG3
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7
Q

A polymorphism in the ______ gene has been linked to susceptibility to the autoimmune disease systemic lupus erythrematosus in humans

A
  • FcgammaRIIB gene
  • (this makes sense because they are not able to activate the inhibitory (FcgammaRIIB) thus they overproduce antibodies
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8
Q

What is antibody-dependent cell-mediated cytotoxicity (ADCC)

A
  • Ab of certain IgG subclasses bind ot infected host cells, and the Fc regions of the bound Ab are recognized by an FcgammaRIII on NK cells
  • The NK cells are activated and kill Ab-coated cells
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9
Q

Worms can be killed by a toxic cationic protein, known as the _______, present in the granules of eosinophils

A

Major basic protein (MBP)

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10
Q

FcepsilonRI binds to ____ and is found on

A
  • Monomeric IgE
  • Found on Mast cells, Basophils, and Eosinophils
  • thus needed to fight parasitic infection
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11
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A
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12
Q
A
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13
Q

The classical pathway is initiated by binding of the ____ to ___ or ___ molecules that bound Ag

A

The classical pathway is initiated by binding of the C1 to IgG or IgM molecules that bound Ag

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14
Q

Among the various IgG subclasses, ____ and ____ are most efficient activators of complement

A

IgG3 and IgG1

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15
Q

C1 is composed of what 3 subunits

A
  • C1q, C1r, and C1s
    • The C1q binds to Ab, whereas C1r and C1s are proteases
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16
Q

What is the classical pathway C5 convertase

A

C4b2a3b

17
Q

What is the classical pathway C3 convertase

A
18
Q

The lectin pathway is triggered by the binding of

A

microbial polysaccharides to circulating lectins, such as plasma mannose-binding lectin (MBL)

19
Q

which of the MASPs actually cleaves C4 in the lectin pathway

A

MASP3

20
Q

What are the two componets of the MAC compliment proteins that are in the cell membrane

A

C7 and C8

21
Q

Compliment receptor 1 (CR1) is found on what cell and what functions does it have

A
22
Q

CR2: cell distribution and functions

A
23
Q

CR3 and CR4 cell distribution and fuctions

A
24
Q

What is the difference between CD59 and S protein

A
  • They both inhibit the formation of the MAC complex but do it in different ways
  • CD59 is a membrane protein that inhibits C9 from foring the MAC
  • S protein in the plasma stops the addition of C8
25
Q

What complement deficiency is most common

A

C2 deficiency

26
Q

C1q, C2, and C4 deficiencies are associated with

A
  • systemic lupus erythematosus
    • this is because complement activation defects lead to failure to clear circulating immune complexes. Complexes may be deposited in blood vessel walls and tissues, where they produce local inflammation
27
Q

C3 deficiency is associated with frequent serious

A

pyogenic bacterial infections that may be fatal

28
Q

MAC comlement proteins (C5,C6,C7,C8,C9) deficiences may result in infections by

A

Neisseria bacteria

29
Q

Many pathogens express ____ , which can inhibit the alternative pathway of complement by recruiting Factor H, which displaces C3b from Bb

A
30
Q

HIV incorporates what complement regulatory proteins when it buds from an infected cell

A
  • DAF and CD59
31
Q

Transport of maternal IgG across the placenta and across the neonatal intestinal epithelium is mediated by an IgG-specific receptor called

A

neonatal Fc receptor (FcRn)

32
Q

maternal ___ in breast milk are ingested by the nursing infant

A

IgA.

33
Q
A
34
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35
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36
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A
37
Q

Complement activation is associated with intravascular thrombosis and can lead to

A

ischemic injury to tissues

38
Q

In an autoanitbody-mediated kidney disorder, membranous nephropathy, damage to glomerular epithelial cells can be mediated by the ____ that is generated after Ab binds to a glomerular auto-Ag

A

MAC

39
Q

Many pathogens express _____, which can inhibit the alternative pathway of complement by recuriting Factor H.

A
  • Sialic acids
  • (note: factor H binds C3b and displaces Bb, cofactor for facor I, which cleaves C3b and C4b)