Imm: Exam II Flashcards
(183 cards)
1
Q
PowerPoint 6 Quiz
Which of the following corresponds to the antigen binding site of an immunoglobulin?
A) VL:CL B) CH:CL C) VH:CL D) VH:VL E) VH:CH
A
D) VH:VL
2
Q
PowerPoint 6 Quiz
Each binding site of an immunoglobulin has ____ complementarity determining regions ( CDRs )/ hypervariable regions ( HVs ).
A) 3 B) 5 C) 6 D) 12 E) 24
A
C) 6
3
Q
PowerPoint 6 Quiz
_______ forms dimers, whereas _______ forms pentamers.
A) IgG; IgD B) IgA; IgM C) IgE; IgM D) IgD; IgM E) IgM; IgG
A
B) IgA; IgM
4
Q
PowerPoint 6 Quiz
The antigenic determining region of an antigen is called ____.
A) isotype B) allotype C) epitope D) idiotype E) hapten
A
C) epitope
5
Q
PowerPoint 6 Quiz
A newborn derives passive immunity from its mother by transferring of _____ in breast milk.
A) dIgA B) IgD C) IgE D) IgG E) IgM
A
A) dIgA
6
Q
Topic 6
What is humoral immunity?
A
Immunity that can be transferred as a fluid or serum
7
Q
Topic 6
What is an antigen?
A
A molecule that can be bound by an antibody or B cell and T cell receptors
8
Q
Topic 6
What is antigenicity?
A
The ability to specifically bind to an antibody or B cell and T cell receptors
9
Q
Topic 6
What is an immunogen?
A
An antigen that is able to stimulate an immune response
10
Q
Topic 6
What is immunogenicity?
A
The ability to induce a humoral or cell - mediated immune response
11
Q
Topic 6
Why are all immunogens are antigens, but not all antigens are immunogens?
A
Antigens cannot always stimulate an immune response
12
Q
Topic 6
Ideal immune responses depend on the combination of ____ and ___ of immunization
A
dose; route
13
Q
Topic 6
What are the 5 routes of immunization? Describe each.
A
1) Subcutaneous ( s.c. ): beneath the skin
Under all the skin layers
2) Intraperitoneal ( i.p. ): into the peritoneal cavity
Not in humans, only animals
3) Intravenous ( i.v. ): into a vein
Good results, not very convenient
4) Intradermal ( i.d. ): into the skin
Between the skin layers
5) Intramuscular ( i.m. ): into a muscle
Most common method of injection
14
Q
Topic 6
What do adjuvants do?
A
Enhance immunogenicity; used to help the immunogens
15
Q
Topic 6
What are the 4 ways adjuvants help immunogens?
A
1) Prolong Immunogen persistence
2) Enhance co-stimulatory signals
3) Increase local inflammation
4) Stimulate non-specific proliferation of lymphocytes
16
Q
Topic 6
What is a linear epitope? A discontinuous epitope?
A
Linear: When the proteins that are bound by the antibody are all in a row ( linear )
Discontinuous: When the proteins that are bound by the antibody are not in a row
17
Q
Topic 6
What is a multivalent antigen / antibody?
A
Multivalency is when a protein has several sites at which attachment can occur
A multivalent antigen / antibody occurs when it can bind to more than 1 epitope at a time ( can be many different epitopes or 1 repeated epitope )
18
Q
Topic 6
What is a hapten? What is a carrier?
How do they work together?
A
Hapten: a molecule that is antigenic but not immunogenic
Carrier: a large protein that gives weight to hapten
Work together: Hapten-carrier conjugate
putting the hapten and carrier together to make the immune system recognize the hapten to produce antibodies
19
Q
Topic 6
What are the 2 types of superantigens? What illness are they often involved in?
A
Exogenous superantigen: soluble protein from bacteria or exotoxins
Endogenous superantigen: membrane proteins produced by some viruses
Many food poisonings are caused by bacterial superantigens
20
Q
Topic 6
Is an antibody a monomer, dimer, or trimer?
What are the binding sites (2)?
Connected by what kind of bonds?
A
Monomer
Antigen and epitope binding site
Disulfide bonds
21
Q
Topic 6
What are the antigen binding sites (2)?
A
VL & VH are the antigen binding sites
22
Q
Topic 6
What are the 5 classes of antibodies?
A
IgG, IgM, IgA, IgE, and IgD
23
Q
Topic 6
What are antibody classes determined by?
A
The heavy chain ( heavy chain gamma = IgG, heavy chain alpha = IgA, etc. )
24
Q
Topic 6
How do the 4 subclasses of IgG differ?
A
At the hinge region
25
Topic 6
For IgG1:
1) What is the heavy chain?
2) Length of the hinge region
3) How abundant in serum?
4) Binds to complement?
5) Binds to phagocytes?
6) Unique traits
1) Gamma 1
2) Short
3) Most abundant IgG
4) Yes
5) Yes
6) Involved in placental transfer ( mom --> fetus as passive immunity )
26
Topic 6
For IgG2:
1) What is the heavy chain?
2) Length of the hinge region
3) Binds to complement?
4) Binds to phagocytes?
5) Unique traits
1) Gamma 2
2) Mid-length
3) Weakly
4) No
5) Binds to carbohydrate antigens and neutralization
27
Topic 6
For IgG3:
1) What is the heavy chain?
2) Length of the hinge region
3) Binds to complement?
4) Binds to phagocytes?
5) Unique traits
1) Gamma 3
2) Long
3) Yes, strongly
4) Yes
5) Involved in placental transfer
28
Topic 6
For IgG4:
1) What is the heavy chain?
2) Length of the hinge region
3) Binds to complement?
4) Binds to phagocytes?
5) Unique traits
1) Gamma 4
2) Short
3) Weakly
4) No
5) Weak placental transfer;
Main function: anti - inflammation, inhibit immune responses
29
Topic 6
What does transcytosis do? What is the main protein?
- selectively moves materials between two environments without altering the unique compositions of those environments.
- FcRn
30
Topic 6
Are the hinge regions of IgGs flexible?
YES!
31
Topic 6
For IgM:
1) What is the heavy chain?
2) Binds to complement?
3) Binds to phagocytes?
4) Unique traits
1) mu
2) YES, "IgM’s major function is to activate the complement system"
3) No
4) Very first antibody produced in response to an antigen; In its membrane bound form, it is involved in B cell development
32
Topic 6
For IgA:
1) What is the heavy chain?
2) Monomer or dimer?
3) What are the subclasses?
4) Unique traits
1) alpha 1/2
2) Can be present as both
3) IgA1 and IgA2
4) Dimeric IgAs ( Secretory ) are constantly being made because they are good neutralization antibody; Not involved in placental transfer, but transfer through milk ( mother to baby )
33
Topic 6
For IgD:
1) What is the heavy chain?
2) Binds to complement?
3) Binds to phagocytes?
4) Unique traits
1) Delta
2) No
3) No
4) Sensitizes basophils; Anti - respiratory infectious;
In it membrane bound form, it is involved in B cell development
34
Topic 6
For IgE:
1) What is the heavy chain?
2) How abundant in serum?
3) Binds to complement?
4) Binds to phagocytes?
5) Unique traits
1) Epsilon
2) Least abundant
3) No
4) No
5) Strongly binds to mast cells (sensitizes), activates eosinophils and basophils
35
Topic 6
All antibodies are produced by what?
Plasma cells, differentiated from B cells
36
Topic 6
What immunoglobulins transfer antibodies via the following methods?
Blood:
Extracellular fluid:
Mucosal epithelia:
Connective tissue:
Bank: IgM, IgE, IgG, dIgA, IgA, mIga
Blood: IgM, IgG ( passive immunity ), IgA
Extracellular fluid: IgG, mIgA
Mucosal epithelia: dIgA ( passive immunity )
Connective tissue: IgE
37
Topic 6
When are babies most susceptible to infections?
Where do they receive IgGs from?
- Before 1 year old
| - Mother's milk
38
Topic 6
What kinds of bonds hold an antibody together?
Disulfide
39
Topic 6
Antibodies are made of ___ and ___ chains
Light; heavy
40
Topic 6
What is the definition of Isotype?
Different groups of antibodies determined by the constant regions of the heavy chain.
Different isotopes have different structures and different biological functions
41
Topic 6
What is the definition of anti-isotype antibody?
The idea that different species have different isotopes
42
Topic 6
What is the definition of allotype?
antibodies encoded by the gene alleles that are different between individuals among the population ( each human’s could be different from one another). They have the same biological function
43
Topic 6
What is the definition of anti-allotype antibody?
The idea that different individuals in the same species have different allotypes
44
Topic 6
What is the definition of an idiotype?
determined by the different V-regions generated by Ig gene recombination and mutation. They bind to different antigen, but have the same biological function.
45
Topic 6
What is the definition of an anti-idiotype antibody?
In the same individual
46
Topic 6
What is a Hypervariable Region ( HV )? What is it also known as?
- A major binding site for all the various antigens
| - Complementarity determining regions ( CDRs )
47
Topic 6
What types of bonds are involved in antibody / antigen interaction
Anything but covalent bonds
48
Topic 6
Ag - Ab ( antigen - antibody ) Cross Reactivity is the cause of what type of disease?
Autoimmune diseases
49
Topic 6
What is the definition of affinity?
the binding strength between a single antigen-binding site on an antibody and a single epitope
50
Topic 6
What is the definition of avidity?
the combined strength of multiple interactions between an multivalent antibody and antigen ( having multi - epitopes )
51
Topic 6
An antibody’s biological function is mediated by ___ receptors
Fc
52
Topic 6
What receptor binds to what isotype?
Anything gamma binds to IgG, anything epsilon binds to IgE, anything alpha binds to IgA
53
Topic 6
What is the function of neutralization?
Block antigen infection
54
Topic 6
What is the function of opsonization?
Promotion of phagocytosis of antigen by macrophages and neutrophils
55
Topic 6
Which immunoglobulins activate the classical pathway of the complement system?
IgM and IgG
56
Topic 6
What are the four types of therapeutic monoclonal antibodies? Describe each
Mouse: all mouse
Chimeric: Keeps original CDRs so you can bind to the target
Humanized: Keeps part of the original CDRs so you can bind to the target
Human: all human
57
Topic 6
What do monoclonal antibodies do?
- prevent anti-antibody immune response
| - engage the human effector cells through Fc region
58
PowerPoint 7 quiz
If a person carries a γ3 immunoglobulin gene mutation and can't make γ3 heavy chain protein, what will be the antibody class that the person cannot produce?
```
A) IgG1
B) IgG2
C) IgG3
D) IgM
E) IgE
```
C) IgG3
γ = gamma = G
59
PowerPoint 7 quiz
FcγRIII receptor binds to___.
```
A) Fc region of IgA
B) Fc region of IgD
C) Fc region of IgG
D) Fc region of IgE
E) Fc region of IgM
```
C) Fc region of IgG
γ = gamma = G
60
PowerPoint 7 quiz
Antibody's biological functions include all of these EXCEPT___.
A) activation of the classical pathway of the complement system
B) neutralization of pathogens
C) activation of phagocytosis
D) activation of T cells
E) initiation of antibody-determined cell-mediated cytotoxicity (ADCC)
D) activation of T cells
61
PowerPoint 7 quiz
The immunoglobulin heavy-chain gene consists of _______ segments, whereas the immunoglobulin light-chain gene consists of _______ segments.
```
A) V, D, and J; V and J
B) κ; λ
C) V and J; V, D, and J
D) P; N
E) RAG-1; RAG-2.
```
A) V, D, and J; V and J
62
PowerPoint 7 quiz
Which of the following describes two recombination signal sequences (RSS) required for a permitted somatic recombination event?
```
A) VH 7-12-9::9-12-7 JH
B) V 7-23-9::9-23-7 J
C) V 7-12-9::7-23-9 J
D) VH 9-23-7::7-12-9 DH
E) DH 7-12-9::9-23-7 JH
```
E) DH 7-12-9::9-23-7 JH
63
Topic 7
How many identical antigen binding sites to antibodies have?
How many domains in each? What are the domains?
2
2
One heavy chain ( VH ) and one light chain ( VL )
64
Topic 7
What is a hypervariable (HV ) / complementary determining ( CDR ) region?
Gives each antibody the chance to form a unique physiological configuration; allows that antibody to associate with its target antigen or epitope
65
Topic 7
What are framework regions ( FR ) and where are they found?
intervening peptide sequences
in the hypervariable (HV ) / complementary determining ( CDR ) region
66
Topic 7
The number of different antibodies that can be produced by the human body seems to be virtually limitless.
How could this happen ( 3 theories )?
1) Germ - line: large repertoire of Ig genes
2) Two-gene one-polypeptide model ( Dreyer and Bennett )
3) Somatic - variation: small number of Ig genes that undergo mutations or recombination in somatic cells
67
Topic 7
Junctional diversity / flexibility is thanks to ________ and _______ nucleotide addition.
Palindromic ( P ) and none-templated ( N )
68
Topic 7
Does somatic hypermutation and antibody isotype switching happen before or after B cell activation?
After
69
Topic 7
Immunoglobulins have how many loci?
What are they?
3
Lambda light chain, kappa light chain, and heavy chain
70
Topic 7
What differentiating factor does the heavy chain have compared to the Lambda light chain and kappa light chain?
D segments ( 23 of them )
| All three have V, J, C segments
71
Topic 7
Ig genes in their germ line form cannot what?
How can this be fixed?
Be expressed / transcribed
In order for it to be able to be transcribed, it needs to be rearranged
72
Topic 7
In immunoglobulin light chain production, which peptide leaves early?
L
It is the leader peptide
73
Topic 7
In immunoglobulin light chain production, light chain gene segments are ____.
Rearranged
74
Topic 7
In immunoglobulin light chain production, how is which V or J segment to rearrange picked?
It is random
75
Topic 7
How can we tell how many combinations of polypeptide chains the light chain can make (formula)?
λ + κ = VLs
76
Topic 7
In immunoglobulin heavy chain production, how many rearrangement events are there?
2
77
Topic 7
How can we tell how many combinations of polypeptide chains the heavy chain can make (formula)?
VH x VL
78
Topic 7
Due to _____, we can produce a lot more regions of chain production.
the Ig gene rearrangement
79
Topic 7
What are the 2 rules of Ig gene recombination?
1) Recombination only occurs between gene segments on the same chromosome, such as Vk to Jk, V lambda to J lambda
2) It is always DH to JH, then VH to DJH for heavy chain
80
Topic 7
In a recombination signal sequence ( RSS ), there are 2 ______ sequences.
conserved
81
Topic 7
In a recombination signal sequence ( RSS ), what letter(s) will you find at the 3' end? 5' end?
3': V, D
| 5': D, J
82
Topic 7
In a recombination signal sequence ( RSS ), the ____
always directly connects to the gene segment
heptameter ( 7 )
83
Topic 7
In a recombination signal sequence ( RSS ), what is the one turn / two turn rule?
a segment flanked by a 12 bp spacer ( one-turn ) RSS can only join to the one flanked by a 23 bp spacer ( two-turn ) RSS, vice versa
Example: PowerPoint 7 quiz
Which of the following describes two recombination signal sequences (RSS) required for a permitted somatic recombination event?
```
A) VH 7-12-9::9-12-7 JH
( no, can't have 2 12s )
B) V 7-23-9::9-23-7 J
( no, can't have 2 23s )
C) V 7-12-9::7-23-9 J
( no, 7s needs to be @ the end )
D) VH 9-23-7::7-12-9 DH
( no, 7s needs to be @ the end )
E) DH 7-12-9::9-23-7 JH
( yes! )
```
84
Topic 7
In Ig gene recombination, what binds RSS?
RAG - 1:2 ( protein )
85
Topic 7
What cell(s) express RAG 1 and RAG 2?
B cells and T cells
86
Topic 7
What was an experiment used to evidence Ig gene rearrangement?
Southern blotting
87
Topic 7
What greatly increases antibody diversity?
Junctional flexibility ( P and N nucleotide addition)
88
Topic 7
Where does junctional flexibility take place?
CDR3 of a V region
89
Topic 7
What are the three factors, that, together, produce a huge repertoire of Igs?
1) Ig gene segments recombination
2) heavy/light chain recombination
3) junctional flexibility
90
Topic 7
Ig gene rearrangement and P and N nucleotide addition takes place ___ a B cell encounters its antigen, while somatic mutation occurs ____.
Before
After
91
Topic 7
Why are many of the rearrangement products unproductive?
The random additions of P and N nucleotides shift the open reading frame, generating stop codons
92
Topic 7
What does somatic hypermutation do?
Furthers Antibody Diversity
93
Topic 7
What initiates somatic hypermutation?
Activation-induced cytidine deaminase ( AID; expressed only by B cells )
94
Topic 7
What is necessary for AID ( Activation - Induced Deaminase ) to occur?
Helper T cells
95
Topic 7
What is sterile transcription?
DNA sequence does not have the stop codon and no cap is present = no transcription
96
Topic 7
What occurs in AID ( Activation - Induced Deaminase ) that requires repair?
Cytosine is deaminated ( amino group C removed ) to form Uracil ( U ).
No U in DNA, so repair occurs
97
Topic 7
Ig gene V region mutation rate is (more or less) than ordinary mutation rate
More
98
Topic 7
Why is the Ig gene V region mutation rate so high ( why do we want mutation; 2 reasons )?
1) These mutations increase the diversity of immunoglobulins
2) Mutations improve the immunoglobulins antigen binding affinity ( “Affinity maturation “ )
99
Topic 7
Where does Somatic Hypermutation mostly occur and why ( 2 reasons )?
Mostly in the CDR regions
Why?
- The structure, CDR is right on top of the loops
- The transcription opens the DNA double strand, allowing the enzyme to attack the cytidine base ( C )
100
Topic 7
RAG1/2 and TdT are ____ cell specific, while AID is ____ cell specific
B/T
B
101
Topic 7
How does a B cell select which segment for the heavy chain to make?
Isotype Switching
102
Topic 7
If there is no Isotype Switching, what chain(s) will be made?
mu or delta heavy chain
103
Topic 7
What signals are critical for gene isotype switching?
CD40L / CD40 signals
104
Topic 7
What are switch regions?
stretches of repetitive DNAs ( WGCW ) in the introns upstream a C gene segment
Except for Cδ ( C delta )
105
Topic 7
What triggers isotype switching?
environmental changes
106
Topic 7
Does isotype switching change anything in the variable region?
No
107
Topic 7
What does isotype switching change?
The isotypes of the antibody or immunoglobulin
108
Topic 7
Why might new isotopes be needed?
Might need new isotypes as the environment ( cytokine ) changes
109
Topic 7
What determines what heavy chain will be made?
The cytokine profile
110
Topic 7
Without a switch region, how does the B cell decide to make a mu heavy chain or delta heavy chain / IgM or IgD?
Alternative RNA Splicing and Polyadenylation
111
Topic 7
At what level ( DNA or RNA ) does alternative RNA splicing and polyadenylation occur?
Happens at the RNA level
112
Topic 7
pA(mu)M is used in expression of IgM or IgD?
IgM
113
Topic 7
pA(mu)M will remove all C___ segments
Delta
114
Topic 7
pA(delta)M is used in expression of IgM or IgD?
IgD
115
Topic 7
pA(delta)M will remove all C___ segments
Mu
116
Topic 7
Alternative RNA splicing and polyadenylation are important for ____ development
B cell
117
Topic 7
What does mIg stand for?
Transmembrane IgM
118
Topic 7
What does sIg stand for?
Secreted IgM
119
Topic 7
Where is transmembrane IgM ( mIg ) needed?
B cells
120
Topic 7
Where is secreted IgM ( sIg ) needed?
Plasma cells
121
Topic 8
What is the order in which B cells are made and where does each step occur?
1) Pluripotent hematopoietic stem cell ( bone )
2) Common lymphoid progenitor ( lymph node )
3) B cell precursor ( spleen )
4) Pro B cell ( Peyer’s patches )
122
Topic 8
What is the order of B cell functional development and activation?
1) Repertoire assembly
2) Negative selection
3) Positive selection
4) Searching for infection
5) Finding infection
6) Attacking infection
123
Topic 8
Which functional steps of B cell development are antigen independent and which steps are antigen dependent? ( steps not in order )
Bank:
- Searching for infection
- Negative selection
- Attacking infection
- Positive selection
- Repertoire assembly
- Finding infection
- Searching for infection ( D )
- Negative selection ( I )
- Attacking infection ( D )
- Positive selection ( I )
- Repertoire assembly ( I )
- Finding infection ( D )
124
Topic 8
What are the stages of B cell development and Ig gene rearrangement? ( 6 )
1) Stem cell
2) Early pro B cell
3) Late pro B cell
4) Large pre B cell
5) Small pre B cell
6) Immature B cell
125
Topic 8
At the immature B cell stage of B cell development, L chain genes are __ and ___ rearranged.
V;J
126
Topic 8
At the immature B cell stage of B cell development, H chain genes are __, ___, and ____ rearranged.
V;D;J
127
Topic 8
What type of stromal cells are important for B cell development?
Bone marrow stromal ( BMS )
128
Topic 8
What do bone marrow stromal ( BMS ) cells do to developing B cells? ( 2 )
- form specific adhesive contacts with developing B cells
| - provide growth factors that stimulate differentiation and proliferation
129
Topic 8
What are the growth factors that bone marrow stromal ( BMS ) cells provide? ( 4 )
- SCF: stem cell factor ( membrane bound )
- SDF-1: stromal cell-derived factor 1
- PBSF: pre-B cell growth-stimulating factor
- IL-7
130
Topic 8
Where are pro B cells derived from?
pluripotent hematopoietic stem cells
131
Topic 8
What are the two stages of the pro B cells? What is the joining factor of each?
Early pro B cell: D to J joining – on both loci
Late pro B cell: V to DJ joining – only one locus at a time
132
Topic 8
____% of pro B cells go on to become pre B cells
50
133
Topic 8
What chain is associated with the pre B cell?
Mu / μ
134
Topic 8
What is the pre B cell receptor used for?
Used to check and see if everything is ok ( first checkpoint in B cell development )
135
Topic 8
What are the surrogate light chains on the pre B cell receptor? ( 2 )
Lambda 5 and V preB
136
Topic 8
What are the signaling proteins of the pre B cell receptor? ( 2 )
Igα and Igβ
137
Topic 8
In the large pre B cell, is the light or heavy chain present?
Heavy chain is present, light chain is not
138
Topic 8
What is the major difference between a pre B cell receptor and a real B cell receptor?
Pre B cell receptor light chains are not covalently bonded with the heavy chain
139
Topic 8
What does the pre B cell receptor do in terms of allelic exclusion?
Halt RAG-1 & -2 expression and stop rearrangement of the other Ig gene heavy chain
only one rearranged light chain Ig gene expressed
140
Topic 8
What happens in the small pre B cell stage? What is the order of events? ( 2 )
Light chain rearrangement begins ( easier because there is no D segment in the light chain )
κ light chain first, λ light chain second
141
Topic 8
What is the success rate of small pre B cell rearrangement (light chain)?
85% success rate, instead of 50% in heavy chain
142
Topic 8
What will happen if the immature B cell stage is a success? Failure?
Succeed: develop further
Form binding site
Correctly associate with the heavy chain
Fail: rearrange other light chain Ig genes ( 4 )
143
Topic 8
How much IgM and IgD is expressed at the immature B cell stage?
IgM is high & IgD is low
144
Topic 8
What are the " fate determining checkpoints " of B cells development? ( 2 )
1: Large pre B cell
2: Light chain check
145
Topic 8
In Ig gene rearrangement, what do the stromal cell factors induce? ( 2 )
Pax-5 and RAG -1/2
146
Topic 8
In Ig gene rearrangement, what does Pax-5 do?
binds to enhancers and opens the promoters
147
Topic 8
In Ig gene rearrangement, what does RAG - 1/2 do?
starts rearrangements with other proteins
148
Topic 8
Why does a B cell perform allelic exclusion?
to make homogeneous antibodies
149
Topic 8
What is the definition of clonal deletion?
Immature B cells that react to a multivalent self antigens in bone marrow will enter apoptosis, but they can be rescued by receptor editing
150
Topic 8
What is the definition of anergy?
Immature B cells that react to monovalent self antigen will enter a state of permanent unresponsiveness until they die – IgM kept in cell
151
Topic 8
What is the definition of peripheral tolerance?
Immature B cells responsive to self-tissue specific antigens in circulation will die by apoptosis or will be rendered anergic
152
Topic 8
What is the definition of no self reaction?
Only those immature B cells that do not react to self antigens will become mature B cells
153
Topic 8
Do cells want to receive positive selection?
Yes, those that receive the signal survive
154
Topic 8
What must cells pass through to become mature B cells?
primary follicles in a secondary lymphoid tissue
155
Topic 8
Immature B cells express ___ IgM, __ IgD
Mature B cells express __ IgM, __ IgD
( low or high )
high
low
low
high
156
Topic 8
What drives B cells maturation?
Follicular dendritic cells ( FDC )
157
Topic 8
Mature B cells enter secondary lymphoid tissues via ____ or ______
Blood Vessels
Lymphatics
158
Topic 8
B cell activation requires 3 signals. What are they?
Signal 1) B-cell receptor
Signal 2) B-cell co-receptor
Signal 3) T cell independent or dependent
159
Topic 8
What is the prerequisite to serve as a B cell receptor?
Must be a membrane bound immunoglobulin
160
Topic 8
In B cell activation signal #1, what is required?
B cell activation requires cross linking of BCRs
161
Topic 8
B cell activation signal #1 expresses what? What does it do?
a homogeneous immunoglobulin ( increases binding specificity and binding affinity )
162
Topic 8
B cell activation signal #2 expresses what?
complex of cell-surface molecules: CD19, CR2, & CD81
163
Topic 8
What does CD19 ( B cell activation signal #2 ) do?
B cell marker
164
Topic 8
What does CD81 ( B cell activation signal #2 ) do?
Brings CD19 to the cell surface
165
Topic 8
What does CR2 ( B cell activation signal #2 ) do?
Binds C3d fragments
166
Topic 8
B cell activation signal #3 can be what? ( 2 )
T cell independent
or
T cell dependent
167
Topic 8
In signal #3, is the toll-like receptor ( TLR ) associated with T cell independent or T cell dependent activation?
independent
168
Topic 8
In signal #3, are the high density, repetitive carbohydrates or proteins ( B-1 cells ) associated with T cell independent or T cell dependent activation?
independent
169
Topic 8
In signal #3, are helper T cells ( CD4 TFH ) associated with T cell independent or T cell dependent activation?
dependent
170
Topic 8
In signal #3, is
- Somatic hypermutation (affinity maturation)
- Class (isotype) switching
- Generation of memory B cells
associated with T cell independent or T cell dependent activation?
dependent
171
Topic 8
A toll-like receptor ( TLR ) activated B cell only produces what?
IgM in the secreted form
172
Topic 8
In T-B conjugation, the
B cell presents a pathogenic antigen to a T cell using what?
Major Histocompatibility Complex ( MHC )
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What is the primary and secondary focus of activating B cells?
Primary: IgM production
Secondary: form the germinal center
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What happens in the germinal center?
Lymphoblasts proliferate rapidly and differentiate in to centroblasts ( dark zone )
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What is the goal of centroblasts?
to improve the immuniglobulin’s binding specificity and binding ability
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What decides what isotype will be made?
The signal factors from T cells ( cytokine profile ) will decide what isotype to make ( IgG, IgD, IgE, etc )
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What do centroblasts become?
Centroblasts change to centrocytes ( light zone ), which are programmed to die unless they bind to their antigens with high affinities
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What helps B cells to differentiate into plasma or memory B cells?
IL-10 and IL-21 from TFH
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When do B 1 cells develop? B 2 cells?
- in fetal liver in early embryonic development
| - over entire lifetime
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B 1 cells can renew themselves, a stem cell feature. What is the problem with this?
renewable cells are likely to produce cancer ( leukemia )
Origin of B-cell tumor - chronic lymphocytic leukemia ( CLL )
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What is the unique marker all B 1 cells have?
CD5
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Where are B 1 cells found?
peritoneal and pleural cavities
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B 1 cells produce ___ binding affinity IgM at absence of antigen ( innate immunity )
( high or low )
low
