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Immunology - Test 3 AH > Chapter 13 - Effector Mechs > Flashcards

Chapter 13 - Effector Mechs Flashcards

0
Q

what effector function does a NK cell have?

A

Ab-dependent cellular cytotoxicity

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1
Q

What are 4 effector functions of Abs against microbes and toxins?

A

neutralization
opsonization for phagocytosis
sensitize them for Ab-dependent cellular cytotoxicity
activate the complement sytem

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2
Q

Polio is neutralized by what?

A

mucosal IgA

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3
Q

tetanus and diptheria are neutralized by what?

A

systemic IgG

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4
Q

Hepatitis A/B is neutralized by what?

A

mucosal IgA or systemic IgG

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5
Q

pneumococcal pneumonia and haemophilus involve what mechanism of protection?

A

opsonization and phagocytosis by IgM and IgG, directly or secondary to complement activation

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6
Q

what does LPS cause and what kind of bacteria is it?

A

gram (-), causes endotoxin shock and cytokine storm

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7
Q

Fc-gamma-RI has what kind of affinity?

what cells use it?

what is its function?

A

(CD64) high IgG1 and IgG3

macrophages, neutrophils, eosinophils

phagocytosis and cell activation

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8
Q

Fc-gamma-RII has what kind of affinity?

what cells use it?

what functions does it have?

A

(CD32), low affinity

macrophages, neutrophils, DCs, B cells, NK cells

phagocytosis, cell activation, feedback inhibition

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9
Q

Fc-gamma-RIII has what kind of affinity?

What cells use it?

What is the function?

A

(CD16), low

NK cells

Ab-dependent cell-mediated cytotoxicity

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10
Q

FC-epsilon-RI has what kind of affinity?

what cells use it?

what are the functions?

A

High for IgE

Mast cells, basophils, eosinophils

cell activation (degranulation)

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11
Q

What has been linked to susceptibility to the autoimmune disease systemic lupus erythematosus?

A

polymorphism in the Fc-gamma-RIIB gene

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12
Q

what is Ab-dependent cell-mediated cytotoxicity (ADCC)?

A

Ab of IgG subclasses bind to infected cells, the Fc regions are recognized by Fc-gamma-RIII on NK cells and kill Ab-coated cells

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13
Q

What functions together to mediate the killing and expulsion of helminthic parasites?

A

IgE, eosinophils and mast cells

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14
Q

how can worms be killed?

A

toxic cationic protein called major basic protein, present in granules of eosinophils

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15
Q

what does IgE bind to when coating helminths?

A

Fc-Epsilon-RI on eosinophils which causes degranulation –> kill parasites

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16
Q

how is the alternative pathway activated?

A

C3b binding to various activating surfaces, spontaneously activated

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17
Q

The classical pathway is activated how?

A

by C1 binding to Ag-Ab complexes (IgM or IgG)

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18
Q

how is the lectin pathway activated?

A

binding of a plasma lectin to microbes

microbial polysaccharides to lectins (MBL)

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19
Q

what leads to the formation of a fluid-phase C3 convertase and the generation of C3b?

A

spontaneous hydrolysis of plasma C3

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20
Q

what forms the alternative pathway C3 convertase?

A

C3b and Factor B

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21
Q

what stabilizes the C3 convertase in the alternative pathway?

A

properdin

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22
Q

what forms the C5 convertase in the alternative pathway?

A

C3b
Bb
C3b

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23
Q

What is C3’s function?

is it high or low [ ]?

A

C3b binds to the surface and functions as an opsonin
component of both convertases
C3a stimulates inflammation (anaphylatoxin)

it is the HIGHEST [ ] in the blood

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24
Q

What is the function of Factor B?

A

Bb is a serine protease and the active of enzyme of both convertases

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25
Q

What is the function of Factor D?

A

plasma serine protease that cleaves Factor B when bound to C3b

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26
Q

TRUE or FALSE?

Soluble IgM and IgG may activate complement system?

A

FALSE - soluble forms of Ab render them conformationally inactive

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27
Q

what must C1 bind to in order to initiate the complement cascade?

A

2 or more Fc portions

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28
Q

how can IgG activate complement?

A

after bind to cell surface Ags, adjacent IgG Fc portions can bind and activate C1

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29
Q

how is the classical pathway initiated?

A

binding C1 to Ag-complexed Ab molecules

30
Q

what does C4 bind to?

what cleaves C4?

A

C1q

activated C1s and generates C4b

31
Q

what cleaves C2?

A

C1s generates C2a and C2b (soluble)

32
Q

what makes of the C3 convertase in the classical pathway?

A

C4b

C2a

33
Q

What makes up C5 convertase?

A

C4b
C2a
C3b

cleaves C5

34
Q

What does C1 do?

A

initiates the classical pathway

35
Q

what does C1q do?

C1r?

C1s?

A

binds Fc portion of Ab that has bound Ag

serine protease that cleaves C1s to make it an active protease

serine protease that cleaves C4 and C2

36
Q

what does C4 do?

A

C4b covalently binds to a microbe and complement is activated
C4b binds C2 for cleavage by C1s
C4a causes inflammation (anaphylatoxin)
highest in [ ] in the blood for classical activation

37
Q

What does C2 do?

A

C2a is a serine protease and is the active enzyme of C3 and C5 convertases to cleave C3 and C5

38
Q

how is the Lectin pathway activated?

what does MBL bind to?

A

binding of microbial polysaccharides to circulating lectins, ie MBL

mannose residues on bacterial polysaccharides

39
Q

what are MASP proteins homologous to?

A

C1r and C1s and cleavage of C4 and C2 to activate the complement pathway

40
Q

what is the function of MBL?

A

agglutinin, opsonin, complement fixing

41
Q

what is function of MASP1?

A

forms complex with MASP2 and collectins/ficolins and activates MASP3

42
Q

what is the function of MASP2?

A

forms complex with lectins, especially ficolin-3

43
Q

what is function of MASP3?

A

associates with collectins or ficolins and MASP1 and cleaves C4

44
Q

What is function of C5?

A

C5b initiates assembly of the MAC

C5a stimulates inflammation

45
Q

C6 function?

A

binds C5b and accepts C7

46
Q

C7 function?

A

binds to C5b, 6 and inserts into lipid membranes

47
Q

C8 function?

A

binds to C5b, 6, 7 and initiates the polymerization of C9

48
Q

C9 function?

A

polymerizes to form membrane pores

49
Q

what makes up the MAC?

A

C5b, 6, 7, 8, 9

50
Q

what does CR1(CD35) do?

describes its affinity

A

phagocytosis of C3b and C4b coated particles and clearance of immune complexes from circulation

high affinity for C3b and C4b

51
Q

What else is CR1 used for?

A

phagocytes use this receptor to bind and internalize microbes and debris (clearance), transduces signal that activates killing mechs

52
Q

CR2 (CD21) binds what?

What does it do on B cells?

A

cleavage products of C3b (C3d, C3dg > iC3b)

enhances responses of B cells to Ag (coreceptor for B cell activation)

53
Q

what is CR2 a receptor for?

On follicular DC, what does CR2 trap?

A

Epstein-Barr virus

iC3-coated Ag-Ab complexes in GCs

54
Q

CR3 (Mac-1) is what? what is its function?

what does it recruit?

A

integrin, functions as a receptor for the iC3b fragment generated by proteolysis of C3b

leukocytes to sites of infection and tissue injury by binding ICAM-1 on endothelial cells

55
Q

what does C4 bind?

function?

A

iC3b

similar to Mac-1

56
Q

What does C1 inhibitor do?

A

displaces C1r2s2 from C1q and term. classical act.

57
Q

what does Factor I do?

what does Factor H do?

A

cleaves C3b and C4b

binds C3b and displaces Bb, cofactor for factor I

58
Q

what does the MCP do?

A

cofactor for factor I-mediated cleavage of C3b and C4b

59
Q

what does DAF do?

A

classical C4b2a or alternative C3 convertase can be dissociated by DAF

MCP and CR1 function similarly

60
Q

What do MCP/CR1 do to Factor I?

A

cleaves membrane bound C3b, renders it inactive (iC3b)

61
Q

what membrane protein may inhibit formation of the MAC

A

CD59 and S protein in the plasma

62
Q

what are some of the functions of complement system

A

phagocytosis of microbe
recruitment and act. of leukocytes by C5a, C3a
destruction of microbes by leukocytes
osmotic lysis of bacteria

63
Q

what is the most common hum deficiency?

A

C2 deficiency

64
Q

what deficiencies develop systemic lupus erythematosus?

A

C1q, C2, and C4

65
Q

what deficiency is associated with pyogenic bacterial infections that may be fatal?

A

C3

66
Q

Deficiencies in properdin and Factor D result in what?

A

increased susceptibility to infection with pyogenic bacteria

67
Q

Deficiencies in C5, 6, 7, 8, and 9 result in what?

A

disseminated infections by Neisseria bacteria

68
Q

what conditions is complement activation associated with?

A

intravascular thrombosis and can lead to ischemic injury to tissues

69
Q

what happens in membranous nephropathy?

A

kidney disorder, damage to glomerular epithelial cells mediated by the MAC after Ab binding to glomerular auto-Ag

70
Q

microbes evade the complement by expressing what?

A

sialic acids, inhibit alt. pathway of complement by recruiting Factor H which displaces C3b from Bb

71
Q

what does HIV incorporate?

A

GPI-anchored DAF and CD59

72
Q

what is transcytosis?

A

process in which Abs in ingested milk transported across the gut epithelium of newborns

73
Q

what is found in breast milk?

A

IgG and IgA

Immunology - Test 3 AH (6 decks)

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