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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
What is the function of Factor B?
Bb is a serine protease and the active of enzyme of both convertases
25
What is the function of Factor D?
plasma serine protease that cleaves Factor B when bound to C3b
26
TRUE or FALSE? Soluble IgM and IgG may activate complement system?
FALSE - soluble forms of Ab render them conformationally inactive
27
what must C1 bind to in order to initiate the complement cascade?
2 or more Fc portions
28
how can IgG activate complement?
after bind to cell surface Ags, adjacent IgG Fc portions can bind and activate C1
29
how is the classical pathway initiated?
binding C1 to Ag-complexed Ab molecules
30
what does C4 bind to? what cleaves C4?
C1q activated C1s and generates C4b
31
what cleaves C2?
C1s generates C2a and C2b (soluble)
32
what makes of the C3 convertase in the classical pathway?
C4b | C2a
33
What makes up C5 convertase?
C4b C2a C3b cleaves C5
34
What does C1 do?
initiates the classical pathway
35
what does C1q do? C1r? C1s?
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
what does C4 do?
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
What does C2 do?
C2a is a serine protease and is the active enzyme of C3 and C5 convertases to cleave C3 and C5
38
how is the Lectin pathway activated? what does MBL bind to?
binding of microbial polysaccharides to circulating lectins, ie MBL mannose residues on bacterial polysaccharides
39
what are MASP proteins homologous to?
C1r and C1s and cleavage of C4 and C2 to activate the complement pathway
40
what is the function of MBL?
agglutinin, opsonin, complement fixing
41
what is function of MASP1?
forms complex with MASP2 and collectins/ficolins and activates MASP3
42
what is the function of MASP2?
forms complex with lectins, especially ficolin-3
43
what is function of MASP3?
associates with collectins or ficolins and MASP1 and cleaves C4
44
What is function of C5?
C5b initiates assembly of the MAC C5a stimulates inflammation
45
C6 function?
binds C5b and accepts C7
46
C7 function?
binds to C5b, 6 and inserts into lipid membranes
47
C8 function?
binds to C5b, 6, 7 and initiates the polymerization of C9
48
C9 function?
polymerizes to form membrane pores
49
what makes up the MAC?
C5b, 6, 7, 8, 9
50
what does CR1(CD35) do? describes its affinity
phagocytosis of C3b and C4b coated particles and clearance of immune complexes from circulation high affinity for C3b and C4b
51
What else is CR1 used for?
phagocytes use this receptor to bind and internalize microbes and debris (clearance), transduces signal that activates killing mechs
52
CR2 (CD21) binds what? What does it do on B cells?
cleavage products of C3b (C3d, C3dg > iC3b) enhances responses of B cells to Ag (coreceptor for B cell activation)
53
what is CR2 a receptor for? On follicular DC, what does CR2 trap?
Epstein-Barr virus iC3-coated Ag-Ab complexes in GCs
54
CR3 (Mac-1) is what? what is its function? what does it recruit?
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
what does C4 bind? function?
iC3b similar to Mac-1
56
What does C1 inhibitor do?
displaces C1r2s2 from C1q and term. classical act.
57
what does Factor I do? what does Factor H do?
cleaves C3b and C4b binds C3b and displaces Bb, cofactor for factor I
58
what does the MCP do?
cofactor for factor I-mediated cleavage of C3b and C4b
59
what does DAF do?
classical C4b2a or alternative C3 convertase can be dissociated by DAF MCP and CR1 function similarly
60
What do MCP/CR1 do to Factor I?
cleaves membrane bound C3b, renders it inactive (iC3b)
61
what membrane protein may inhibit formation of the MAC
CD59 and S protein in the plasma
62
what are some of the functions of complement system
phagocytosis of microbe recruitment and act. of leukocytes by C5a, C3a destruction of microbes by leukocytes osmotic lysis of bacteria
63
what is the most common hum deficiency?
C2 deficiency
64
what deficiencies develop systemic lupus erythematosus?
C1q, C2, and C4
65
what deficiency is associated with pyogenic bacterial infections that may be fatal?
C3
66
Deficiencies in properdin and Factor D result in what?
increased susceptibility to infection with pyogenic bacteria
67
Deficiencies in C5, 6, 7, 8, and 9 result in what?
disseminated infections by Neisseria bacteria
68
what conditions is complement activation associated with?
intravascular thrombosis and can lead to ischemic injury to tissues
69
what happens in membranous nephropathy?
kidney disorder, damage to glomerular epithelial cells mediated by the MAC after Ab binding to glomerular auto-Ag
70
microbes evade the complement by expressing what?
sialic acids, inhibit alt. pathway of complement by recruiting Factor H which displaces C3b from Bb
71
what does HIV incorporate?
GPI-anchored DAF and CD59
72
what is transcytosis?
process in which Abs in ingested milk transported across the gut epithelium of newborns
73
what is found in breast milk?
IgG and IgA

Immunology - Test 3 AH (6 decks)

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