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IMMUNO > LECTURE 9 > Flashcards

LECTURE 9 Flashcards

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1
Q

what are the 3 stages of B cells?

A
  1. generation of mature B cells
  2. activation upon encountering antigen
  3. differentiation into plasma and memory
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2
Q

considered to be _______ prior to encountering antigen

A

naive

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3
Q

interaction with antigen causes proliferation and differentiation

A

affinity maturation

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4
Q

what is the total antibody diversity

A

10^10

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5
Q

why is there a constant flow of B cells being killed and made

A

increases probability of a match

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6
Q

progenitor B cells develop in the

A

bone marrow

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7
Q

what are the 2 functions of stromal cells

A
  1. use VCAM to interact with VLA-4 on B cell
  2. uses SCF to interact with CKIT
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8
Q

what does the interaction of C-Kit on B cell by using stromal cell SCF allow

A

expression of IL7R on B cell

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9
Q

contact with stromal cell is no longer needed once ____ is expressed

A

IL7R

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10
Q

stromal cells secrete _____ which allows proliferation and maturation

A

IL7

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11
Q

IL7R + IL7 =

A

1st attempt at VDJ recombination to make B heavy chain

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12
Q

what is formed if the 1st attempt at VDJ recombination to make B heavy chain succeeds?

A

mIgM heavy chain

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13
Q

what does the mIgM heavy chain generate?

A

pre-B receptor

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14
Q

What 2 things does the mIgM heavy chain assemble with in order to make the pre-B receptor

A
  1. V PRE-B
  2. lambda 5
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15
Q

V PRE-B = _______ chain like sequence

A

variable

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16
Q

lambda 5 = ______ chain like sequence

A

constant

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17
Q

pre-B receptor assembles on cell surface with ______/_______ coreceptor

A

Iga/IgB

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18
Q

what does pre-B receptor assembly with Iga/Igb do?

A

starts 2nd attempt of VDJ recombination to make light chain

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19
Q

what happens if 2nd VDJ recombination occurs?

A

forms IgM with light and heavy

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20
Q

what happens after light chain and heavy chain are formed –> IgM

A

attempt antigen recognition

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21
Q

what happens if antigen recognition occurs?

A

apoptosis

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22
Q

what happens if no antigen recognition occurs?

A

IgD expression

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23
Q

does negative selection happen?

A

yes

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24
Q

does positive selection happen?

A

no

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25
what are the 3 main stages of B cell trasnformation
progenitor, pre-B, immature
26
what are the 3 things expressed during progenitor B stage
1. CD45R 2. Iga/IgB coreceptor 3. c-Kit
27
what is CD45R and what does it do?
Tyr phosphatase that regulates signal trasnduction
28
what does cKit do?
helps progression form progenitor stage to Pre-B stage
29
is CKIT expressed during pre-B stage?
no
30
what 2 things are produced during pre-B stage
1. CD25 alpha chain of IL-2 2. Pre-B cell receptor
31
for immature B cells, no longer produce: - - _____ is present ______ is initially absent
for immature B cells, no longer produce: - pre-B receptor - CD25 mIgM is present mIgD is initially absent
32
what trasnduces the signal for counter selection during development?
aggregation of BCR
33
in vitro, addition of what triggers crosslinking of BCRs and apoptosis?
anti-IgM
34
when trying to prove that aggregation and cross linking of BCRs causes apoptosis in vivo, both mice produced
immature B cells in bone marrow
35
when trying to prove that aggregation and cross linking of BCRs causes apoptosis in vivo, the H2K mouse produced __________ in circulation and the H2K/D mouse produced _________
mature B cells no mature B cells
36
why were no mature B cells produced from H2K/D?
they recognized the H2D = cross linking
37
what BCR mIM was introduced into the mice in the proving cross linking experiment
H2D
38
what caused the rare instance of mature B cell from the H2K/D haplotype?
light chain editing
39
what are the 2 types of antigens involved in B cell activation
thymus dependent and thymus independent
40
2 requirements for thymus dependent antigens
1. need direct contact with Th cell 2. need presentation of antigen to be activated
41
do thymus independent antigens require direct contact with Th cell?
no but might still need stimulation by ctyokines
42
what are the 3 thymus independent antigens
1. lipids 2. repetitious proteins 3. repetitious sugar
43
what are the 2 types of thymus independent antigens?
TI-1 and TI-2
44
is TI-1 specific or non-specific?
non-specific
45
is TI-2 specific or non specific?
specific
46
why does TI-2 require for activation?
cytokines produced by Th
47
what happens with high doses for TI-1
1/3 proliferation
48
what happens with low dose for TI-1
more specific proliferation
49
is TI-1 functional in athymic mice?
yes
50
is TI-2 functional in athymic mice?
no
51
how to restore function in athymic mice for TI-2
injecting Th cells
52
are TI-1 mitogen?
yes
53
are TI-2 mitogens?
no
54
TI-2 inactivate ____ ____ _____
immature B cells
55
TI-1 & TI-2 cause no 1. 2. 3.
1. no class switching 2. no affinity maturation 3. no immunological memory
56
57
activation of TI-1 involves PAMPS + TLR or cytokines?
PAMPS + TLR
58
activation of TI-2 involved PAMPS + TLR or cytokines>?
cytokines
59
what is the common signal for both TI-1 and TI-2
antigen interacts with mIg = crosslinking
60
in regards to the pathway for B cell receptor activation, cross linking of mIg recruits _____
PTK
61
what 3 things does PTK have?
BLK FYN LYN
62
what does PTK component do?
phosphorylates ITAMS
63
what happens once the ITAMS are phosphorylated?
recruit SYK
64
what does SYK recruit
BTK
65
what does BTK recruit?
BNLK
66
what is the role of co-receptors?
provide co-stimulatory signal that enhances activation
67
what 3 things does the co-receptor consist of for B cells?
1. CD19 2. CD21 3. CD81
68
out of the 3 co-receptor components, which one has cytosolic domains?
CD21 and CD19
69
CD21 is a receptor for
C3d
70
what do co-receptors basically do?
allow additional phosphorylation of ITAMS --> more adaptors --> more signals --> lower # of antibodies that need to be crosslinked in order to activate T cell
71
without co-receptor how many mIgM must bind to antigen for activation?
10^4
72
with co-receptor how many mIgM must bind to antigen for activation
10^2
73
BCR is ____ times more sensitive if co-receptor is present
100 times
74
how many times greater was recombinant lysozyme response?
1000 to 10,000
75
why was recombinant lysozyme so much more effective?
ensured recruitment of co-receptor
75
most antigens require _______ cells to activate B cells
Th
76
in terms of B cell and Th cell interaction, what does Ag binding to mIgM cause?
CD28 from T cell to interact with CD80/86 from B cell
77
what happens once CD28 interacts with CD80/86 from B cell
T cell expresses CD40 and interacts with CD40 on B cell
78
1st signal for Th cell and B cell interaction
1. antigen binds to mIgM = crosslinking
79
2nd signal for Th cell and B cell interaction
CD40 from B cell + CD40L
80
what are haptens
antigens too small to elicit immune response
81
conjugation of happen to a large carrier molecule increases
immunogenicity
82
why do T cells have to see carrier in order to maintain immunological memory but B cells do
need to process and present carrier, super low chance of doing so
83
what are the 2 primary sites for humoral response
spleen and lymph nodes
84
antigens may be delivered and soluble antigens trapped by what 3 things?
1. interdigitating dendritic cels 2. macrophages 3. follicular dendritic cells
85
primary follicle
B cell activation
86
germinal center
B cell proliferation and differntiation
87
paracortex
initial T/B cell activation
88

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