Lecture 13: Effector Mechanisms of Humoral Immunity Flashcards Preview

Immunology 2.0 > Lecture 13: Effector Mechanisms of Humoral Immunity > Flashcards

Flashcards in Lecture 13: Effector Mechanisms of Humoral Immunity Deck (39):
1

functions of antibodies against microbes and their toxins

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

Hemagglutinin

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What are virulence factors

  • refer to the properties of bacterial gene products that enable a microorganism to cause disease

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

  • IgG1
  • IgG3

7

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

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

8

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

  • 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

9

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

Major basic protein (MBP)

10

FcepsilonRI binds to ____ and is found on 

  • Monomeric IgE
  • Found on Mast cells, Basophils, and Eosinophils 
  • thus needed to fight parasitic infection 

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

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

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

IgG3 and IgG1

15

C1 is composed of what 3 subunits

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

16

What is the classical pathway C5 convertase

C4b2a3b

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What is the classical pathway C3 convertase

18

The lectin pathway is triggered by the binding of

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

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which of the MASPs actually cleaves C4 in the lectin pathway

MASP3

20

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

C7 and C8

21

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

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CR2: cell distribution and functions

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CR3 and CR4 cell distribution and fuctions

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What is the difference between CD59 and S protein

  • 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

What complement deficiency is most common 

C2 deficiency 

26

C1q, C2, and C4 deficiencies are associated with 

  • 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

C3 deficiency is associated with frequent serious 

pyogenic bacterial infections that may be fatal 

28

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

Neisseria bacteria

29

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

30

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

  • DAF and CD59

31

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

neonatal Fc receptor (FcRn)

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maternal ___ in breast milk are ingested by the nursing infant

IgA. 

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Complement activation is associated with intravascular thrombosis and can lead to 

ischemic injury to tissues

38

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

MAC

39

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

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