15: B cell activation and Ab 2

Question 1

how are u heavy chain made

Answer 1

alternative processing of primary RNA Tc for mRNA

Question 2

what are the two forms of u heavy chain

Answer 2

membrane and secreted form

Question 3

what for of u protein is made by activated B cells ag dependent

Answer 3

secreted form

Question 4

what makes membrane u mRNA

Answer 4

resting B cells

Question 5

what are TP, TM, and Cy for u mRNA

Answer 5

tail piece, transmembrane and cytoplasmic segments

Question 6

exons of Cu gene

Answer 6

Cu1, Cu2, Cu3, Cu4

Question 7

how many CH regions of IgG, A, D

Answer 7

3

Question 8

how many CH regions for IgE and IgM

Answer 8

4

Question 9

what causes class switching

Answer 9

Heavy chain switching in TD response

Question 10

what are the different classes of heavy chains

Answer 10

y,a and E

Question 11

where does isotype switching usually occur and what causes it

Answer 11

GC and is driven by TFH cells

Question 12

isotype switching that might occur in extrafollicular foci

Answer 12

driven by Th cells

Question 13

what part of heavy chain leads to class switching

Answer 13

constant regions

Question 14

what determines Ab specificity

Answer 14

variable regions

Question 15

what doesn’t change in isotype switching

Answer 15

Abs specificity because determine by variable and not constant regions

Question 16

what does the ability of B cells to produce many Abs cause

Answer 16

plasticity in humoral immune response

Question 17

why need various classes of Abs

Answer 17

distinct effector fxns and defense against all different types of pathogens

Question 18

what causes class switching

Answer 18

B cells activated by TFH cells with CD40L and cytokine signals

Question 19

IgM fxn

Answer 19

complement activation

Question 20

IgG is for

Answer 20

opsonization, phagocytosis, complement, neonatal immunity

Question 21

of does IgG do neonatal immunity

Answer 21

placental transfer

Question 22

IgE fxn

Answer 22

helminths, mast cell degradatioin

Question 23

what does mast cell degranulation cause by IgE

Answer 23

immediate hypersensitivity

Question 24

what works with IgE

Answer 24

IgG4

Question 25

what cytokine activates IgE and IgG4

Answer 25

IL4

Question 26

what is IgA for

Answer 26

mucosal immunity

Question 27

what activates IgA

Answer 27

TGF-B, April, BAFF

Question 28

how are TH1 cells related to Class switching

Answer 28

when activated, produces IFNy that induces TFH to produce more IFNy that causes IgG

Question 29

how does TH2 cause class switching

Answer 29

IL-4 causes IgE class switching

Question 30

what Ig is used for intracellular pathogens

Answer 30

IgG Abs

Question 31

what does IgG do

Answer 31

block entry microbes, activate complement and cause phagocytosis by macrophages

Question 32

what does IgE do for helminths elimination

Answer 32

eosinophil and mast cell activation

Question 33

what controls class switching

Answer 33

location of B cells and controlled by local cytokines

Question 34

mucosal B cells cause

Answer 34

IgA

Question 35

what cytokines induce IgA

Answer 35

TGF-B and BAFF

Question 36

where does TGF-B come from

Answer 36

T reg, macrophages

Question 37

BAFF is produced from

Answer 37

DCs and Macrophages

Question 38

what family does BAFF belong to

Answer 38

TNF

Question 39

how does CD 40 contribute to isotype switching

Answer 39

works with cytokines

Question 40

what is the enzyme used for isotype switching and affinity maturation

Answer 40

activation-inducing deaminase (AID)

Question 41

what induces AID

Answer 41

CD40 engagement

Question 42

what happens when CD40 is deficient

Answer 42

Ag is dominated by IgM for limited switching

Question 43

what change in IgM mRNA for IgG1

Answer 43

loop out deletion of Cu, C delta and Cy3 for only Cy1

Question 44

what controls how Ig mRNA gets rearranged

Answer 44

switching sequence before C genes

Question 45

where does class switching recombination occur and how

Answer 45

activated B cells by changing Cu gene to CH genes

Question 46

what does CSR precede

Answer 46

Germline Tcs

Question 47

what initiates Germline Tc

Answer 47

intronic promoters

Question 48

how do germline Tc work

Answer 48

open chromatin of S region to make more accessible to recombinase

Question 49

how does CSR make a looped-out deletion

Answer 49

goes between two switch regions with repetitive sequences for loop

Question 50

what regulates CSR

Answer 50

cytokines

Question 51

how do all immunoglobin isotypes relate

Answer 51

similar Ag specificity with different biological properties

Question 52

how does AID work

Answer 52

deaminates cytosines in ssDNA to convert C to U

Question 53

what happens after AID creates U

Answer 53

Uracil N Glycosylase removes U for apurinic/ apyrimidinic endonuclease (APE1) to create nicks

Question 54

what does the nick by APE1 lead to

Answer 54

ds breaks

Question 55

what does affinity maturation cause

Answer 55

increased affinity of Abs for Ag

Question 56

where is the only place that affinity maturation occurs

Answer 56

TD Ags

Question 57

what causes mutation of IgV genes

Answer 57

TFH with CD40/CD40L interactions

Question 58

GC reaction needed because

Answer 58

make B cells with high affinity Ag receptors to produce Abs with highest affinity for Ag

Question 59

B cells survive by

Answer 59

high affinity Ig that binds FDC presenting Ags

Question 60

how much is affinity increased by changing an AA

Answer 60

10 fold

Question 61

how does Ig V gene get mutated

Answer 61

point mutations at high rate

Question 62

how many pt mutations of IgV genes

Answer 62

1 in 10^3

Question 63

how much higher is mutation rate for V genes than others

Answer 63

1000x higher

Question 64

how many VH and VL genes are in each B cell

Answer 64

700

Question 65

how many mutations in V region

Answer 65

one per cell division

Question 66

due to B cell clones having V mutations, how different are IgGs from each other

Answer 66

5% germline for 10aa substitiution

Question 67

where do most V mutations occur and why

Answer 67

V regions at Ag binding region to increase affinity

Question 68

which Ig has more mutations

Answer 68

IgG

Question 69

what does a B cell to APC FDC result in

Answer 69

rescue B cells from apoptosis

Question 70

B cells to TFH result in

Answer 70

B cell survival for CD 40 dependent

Question 71

why is GC a B cell graveyard

Answer 71

somatic mutation produce B cells without high affinity as well for apoptosis

Question 72

where do B cells go after somatic mutation

Answer 72

FDC light zone

Question 73

how does Ag recognition lead to B cell survival

Answer 73

induces expression of BCl-2

Question 74

how is B cell survival promoted when when B cell binds Ag

Answer 74

once presents Ag for TFH and bind CD40L, signals survival

Question 75

what do B cells inhibit to promote life

Answer 75

activate endogenous inhibitors of Fas by BCR to Ag recognition

Question 76

where does FasL come form and what does it induce

Answer 76

TFH expresses FasL and it causes apoptosis

Question 77

how do B lymphomas develop

Answer 77

B cells in germinal centers

Question 78

what causes B lymphomas

Answer 78

chromosomal translocation of various oncogenes in Ig gene

Question 79

what causes the incorporation of oncogenes into Ig genes

Answer 79

DNA breaks by hypermutation and isotype switching

Question 80

what diseases do GC contribute to

Answer 80

autoimmunity and B cell lymphomas

Question 81

why are GC centers related to Autoimmunity

Answer 81

Somatic mutations may produce self-reactive B cell clones

Question 82

what are plasma cells for

Answer 82

Ab production

Question 83

what activates plasma cells

Answer 83

signals from BCR, CD40, TLR and other cytokine receptors

Question 84

what makes Short lived plasma cells

Answer 84

extrafollicular compartment in TI response as well as early TD response by extrafollicular B cell foci

Question 85

where are short lived plasma cells found

Answer 85

secondary lymphoid organs and peripheral of non-lymphoid tissue

Question 86

when are Long lived plasma cells made

Answer 86

TD response to proteins Ags in Germinal centers

Question 87

what makes Long lived plasma cells

Answer 87

BCR and IL21

Question 88

what is the precursor of long lived plasma cells

Answer 88

plasmablasts

Question 89

how do plasmablast become long lived plasma cells

Answer 89

generated in GC then home to bone marrow for long lived plasma

Question 90

how do immunizations work

Answer 90

use a T cell dependent Ag so that 2 to 3 weeks later, Bone marrow produces many Abs

Question 91

what maintains plasma cells and ow

Answer 91

BAFF

Question 92

how long can plasma cells secrete Abs

Answer 92

months or years after Ag is no longer present

Question 93

what do Abs provide to body

Answer 93

immediate protection if Ags encountered later

Question 94

how many Abs in blood are made from long lived plasma cells

Answer 94

50%

Question 95

can memory cells become plasma cells

Answer 95

yes

Question 96

pathways of B cells

Answer 96

pre B to Naive to MZ or follicular B