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Immunology Exam One > B Cells and Antibodies > Flashcards

B Cells and Antibodies Flashcards

1
Q

How many kinds of B cells are there?

A

100 million

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2
Q

How many B cells are in the blood and how many new ones are produced every day?

A

3 billion in blood

1 billion new ones every day

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3
Q

What do antibodies (immunoglobins), which are Y-shaped, attach to and why?

A

Attach to antigens-usually carb or protein

Helps identify and destroy harmful non-self

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4
Q

What is an antigen?

A

Something that causes the immune system to create antibodies specifically targeting that something

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5
Q

What is a cognate antigen?

A

An antigen that a given B cell’s receptors recognize

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6
Q

What is an epitope (antigenic determinant)?

A

Part of the antigen that the antibody recognizes and attaches

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7
Q

What is a paratope?

A

Part of the antibody that recognizes and attaches to the epitope

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8
Q

How do we create antibody diversity?

A

Modular design

Junctional diversity

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9
Q

Do B cells have to transcribe and translate antibodies?

A

Yes-just like any other protein

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10
Q

Since each person’s cells have the same DNA, is B cell DNA the same?

A

No, B cell DNA has much, much more variety

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11
Q

What is a codon?

A

3 successive base pairs

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12
Q

What is one amino acid?

A

Each 3 consecutive bases

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13
Q

What is meant by modular design in antibody diversity?

A

There are multiple copies of 4 gene segments that code the antibody’s heavy chain: V, D, J, C
When adult, the B cell chooses 1 kind of gene segment from each of these 4
V has the greatest variety

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14
Q

The light chain on an antibody lacks what region?

A

D

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15
Q

What (stringed)lettered region makes up the Fc region on the antibody?

A

C

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16
Q

What does the Fc region code for?

A

The constant region

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17
Q

What are the default for making the BCR?

A

IgM and IgD because they are first in line

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18
Q

Do light or heavy chains have more gene segments to choose from?

A

Light chain

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19
Q

What is meant by junctional diversity in antibody diversity?

A

Additional DNA bases are added or subtracted when the gene segments are joined together
-Increases the number of different antibodies able to be made

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20
Q

Where are antibodies attached to?

A

Surface of B cell called BCR

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21
Q

Are all BCRs the same?

A

Yes

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22
Q

What is a naive or virgin B cell?

A

A B cell that has never encountered its cognate antigen

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23
Q

What is an experienced B cell?

A

A B cell that has been activated

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24
Q

What are the 2 signals necessary for B cells to be activated?

A
  1. Clustering of B cell receptors
  2. Co-stimulatory signal
    - T cell dependent
    - T cell independent (pattern recognition)
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25
How does the B cell signal the nucleus about its cognate antigen using the antibody?
- Paratope binds to epitope - Multiple antigens or sites on antigen bind to BCR - BCRs cluster/crosslink - Ig alpha and Ig beta interact with enzymes in cell - When clustered together signal is big enough to activate nucleus
26
How does the B cell signal the nucleus about its cognate antigen not using the antibody?
- B cells have another protein (complement receptor) on their membranes - B cell's BCR can bind to antigen - B cell's complement receptors can bind to complement protein fragments which are bound to antigen - BCR cluster signals nucleus
27
When BCR and complement receptors are brought together on an opsonized antigen, there is a decreased or increased number (100x) of BCRs that need to be clustered to signal the nucleus?
DECREASED
28
What is T cell dependent co-stimulation?
Usually B cell is stimulated by the antigen and a helper T cell
29
What is T cell independent co-stimulation?
Some antigens have repeating patterns (repeating disaccharides) and will heavily cluster BCRs
30
What happens in T cell dependent co-stimulation?
- The B cell encounters its cognate antigen - Some of the cognate antigen is endocytosed - The peptide fragments of the cognate antigen are presented on MHC IIs on the surface of the B cell - T cell meets its cognate antigen (MHC II peptide on B cell)
31
What happens in un-natural T cell co-stimulation?
- Antigen (mitogen) binds to B cell molecules that are not BCRs - These cluster - BCRs associated with these cluster - Signal not dependent on recognition of the cognate antigen for that B cell
32
What does un-natural T cell co-stimulation result in?
Polyclonal activation of B cells | Not intended by immune system
33
Most B cells become what kinds of cells?
Plasma cells (antibody factories)
34
What happens to B cells after activation and proliferation?
Maturation
35
What are the 3 types of B cell maturation?
- Somatic hypermutation - Career decision - Class switching
36
What are B cells' 2 options for career decision?
- Plasma cell (antibody factory) | - Memory cell
37
What is the normal cell mutation rate in human cells?
1 mutated base pair/100 million bases per DNA replication cycle
38
What is the B cell chromosome mutation rate?
1 mutated base pair/ 1000 bases per DNA replication cycle
39
When do B cell mutations occur?
After V, D, and J gene segments have been selected
40
What happens during somatic hypermutation?
Changing the antigen binding region of the antibody (Fab region)
41
What does somatic hypermutation do to the affinity of the antibody for its cognate antigen?
It may increase, decrease, or have no change on affinity
42
What must happen in order for maturing B cells to continue to proliferate?
An ongoing signal/continually restimulated
43
B cells mutating toward higher affinity BCRs are:
stimulated more easily and multiply
44
B cells mutating toward lesser affinity BCRs are:
not stimulated and cease to multiply
45
What are properties of plasma cells?
- Antibody factories - Spleen or bone marrow - Produces up to 2000 antibodies per second - Lives for only a few days
46
What are properties of memory cells?
- Do not require helper T cell (with CD40) interaction | - Last greater than 50 years
47
What are the classes of antibodies?
IgG, IgA, IgM, IgE, IgD
48
What determines the class of an antibody?
The constant (Fc) region
49
B cells need what to class switch?
T cell help
50
When a naive B cell is first activated, it makes mainly what kind of antibodies?
IgM
51
How does class switching occur?
B cells cut and paste different constant regions
52
What are the functions of antibodies?
- Opsonization - Neutralization of exotoxins - Activation of compliment - Antobody-dependent cell mediated cytotoxicity
53
How many subclasses of IgG are there?
4
54
Which IgG subclass fixes complement better?
IgG3
55
Which IgG subclass helps bind natural killer cells better?
IgG3
56
Which IgG subclass opsonizes pathogens for phagocyte consumption better?
IgG1
57
What are some facts about IgG?
- Can pass from mother's blood to fetus - Longest lived antibody (3 wks) - More IgG in serum than any other antibody - Activates the complement system
58
What is the most abundant antibody class in the human body?
IgA
59
What is the main antibody to guard mucosal surfaces?
IgA
60
What compensates for IgA deficiency?
Secretory IgM
61
Can IgA bind complement?
No
62
What are some functions of IgA?
- Transport into GI tract - From breast milk coats baby's GI tract - Like 2 IgGs clipped together - Can cluster pathogens - Bind and neutralize pathogens and toxins - Export toxins and pathogens
63
How much of normal fecal matter does rejected bacteria make up?
30%
64
What are facts of IgM?
- First immnoglobulin made following antigen recognition - Large - 1/2 life of a day - Immobilizes antigen (agglutination) - Activates complement
65
When are IgE antibodies made?
In response to allergen exposure
66
What does IgE bind to and what happens?
- Binds to surface of mast cells - First exposure causes the first antibodies to be released - Secondary exposure to the allergen is a bigger response - Shock is caused by degranulating mast cells
67
What are the functions of mast cells?
Phagocytize and opsonize bacteria | Protect against parasites
68
How do mast cells protect against parasites?
- Store harsh chemistry (histamine) - Binds IgE and waits for more of the same antigen - Dumps the harsh chemistry on parasites - Process kills parasites, but may cause allergic reaction
69
What part of IgE does mast cells bind to?
Fc region
70
What occurs in a small local impact from the harsh chemistry (histamine) of mast cells?
Increase in capillary permeability (fluid escapes from capillaries to tissue -Usually a local effect-runny nose
71
What occurs in a large systemic impact from the harsh chemistry (histamine) of mast cells?
- Massive degranulation throughout the body can decrease blood volume drastically to the point of a heart attack - Histamine contracts the smooth muscle of respiratory tract-suffacation
72
What is prophylaxis?
- Provide protection - Prevent disease - To guard or prevent beforehand
73
What is anaphylaxis?
Opposite of prophylaxis | -An acute allergic reaction to an antigen
74
What is the function of IgD?
-Function is not completely clear -A lot like IgM B cells don't make it until they leave the bone
75
What controls class switching?
cytokines (T cells)
76
What is passive immunoptherapy?
Endowment of resistance to pathogens by antibody transfer from immune donors (pooled serum) to protect other individuals

Immunology Exam One (4 decks)

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