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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
Q

How does the B cell signal the nucleus about its cognate antigen using the antibody?

A
  • 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
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26
Q

How does the B cell signal the nucleus about its cognate antigen not using the antibody?

A
  • 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
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27
Q

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?

A

DECREASED

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28
Q

What is T cell dependent co-stimulation?

A

Usually B cell is stimulated by the antigen and a helper T cell

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29
Q

What is T cell independent co-stimulation?

A

Some antigens have repeating patterns (repeating disaccharides) and will heavily cluster BCRs

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30
Q

What happens in T cell dependent co-stimulation?

A
  • 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)
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31
Q

What happens in un-natural T cell co-stimulation?

A
  • 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
Q

What does un-natural T cell co-stimulation result in?

A

Polyclonal activation of B cells

Not intended by immune system

33
Q

Most B cells become what kinds of cells?

A

Plasma cells (antibody factories)

34
Q

What happens to B cells after activation and proliferation?

A

Maturation

35
Q

What are the 3 types of B cell maturation?

A
  • Somatic hypermutation
  • Career decision
  • Class switching
36
Q

What are B cells’ 2 options for career decision?

A
  • Plasma cell (antibody factory)

- Memory cell

37
Q

What is the normal cell mutation rate in human cells?

A

1 mutated base pair/100 million bases per DNA replication cycle

38
Q

What is the B cell chromosome mutation rate?

A

1 mutated base pair/ 1000 bases per DNA replication cycle

39
Q

When do B cell mutations occur?

A

After V, D, and J gene segments have been selected

40
Q

What happens during somatic hypermutation?

A

Changing the antigen binding region of the antibody (Fab region)

41
Q

What does somatic hypermutation do to the affinity of the antibody for its cognate antigen?

A

It may increase, decrease, or have no change on affinity

42
Q

What must happen in order for maturing B cells to continue to proliferate?

A

An ongoing signal/continually restimulated

43
Q

B cells mutating toward higher affinity BCRs are:

A

stimulated more easily and multiply

44
Q

B cells mutating toward lesser affinity BCRs are:

A

not stimulated and cease to multiply

45
Q

What are properties of plasma cells?

A
  • Antibody factories
  • Spleen or bone marrow
  • Produces up to 2000 antibodies per second
  • Lives for only a few days
46
Q

What are properties of memory cells?

A
  • Do not require helper T cell (with CD40) interaction

- Last greater than 50 years

47
Q

What are the classes of antibodies?

A

IgG, IgA, IgM, IgE, IgD

48
Q

What determines the class of an antibody?

A

The constant (Fc) region

49
Q

B cells need what to class switch?

A

T cell help

50
Q

When a naive B cell is first activated, it makes mainly what kind of antibodies?

A

IgM

51
Q

How does class switching occur?

A

B cells cut and paste different constant regions

52
Q

What are the functions of antibodies?

A
  • Opsonization
  • Neutralization of exotoxins
  • Activation of compliment
  • Antobody-dependent cell mediated cytotoxicity
53
Q

How many subclasses of IgG are there?

A

4

54
Q

Which IgG subclass fixes complement better?

A

IgG3

55
Q

Which IgG subclass helps bind natural killer cells better?

A

IgG3

56
Q

Which IgG subclass opsonizes pathogens for phagocyte consumption better?

A

IgG1

57
Q

What are some facts about IgG?

A
  • 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
Q

What is the most abundant antibody class in the human body?

A

IgA

59
Q

What is the main antibody to guard mucosal surfaces?

A

IgA

60
Q

What compensates for IgA deficiency?

A

Secretory IgM

61
Q

Can IgA bind complement?

A

No

62
Q

What are some functions of IgA?

A
  • 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
Q

How much of normal fecal matter does rejected bacteria make up?

A

30%

64
Q

What are facts of IgM?

A
  • First immnoglobulin made following antigen recognition
  • Large
  • 1/2 life of a day
  • Immobilizes antigen (agglutination)
  • Activates complement
65
Q

When are IgE antibodies made?

A

In response to allergen exposure

66
Q

What does IgE bind to and what happens?

A
  • 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
Q

What are the functions of mast cells?

A

Phagocytize and opsonize bacteria

Protect against parasites

68
Q

How do mast cells protect against parasites?

A
  • 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
Q

What part of IgE does mast cells bind to?

A

Fc region

70
Q

What occurs in a small local impact from the harsh chemistry (histamine) of mast cells?

A

Increase in capillary permeability (fluid escapes from capillaries to tissue
-Usually a local effect-runny nose

71
Q

What occurs in a large systemic impact from the harsh chemistry (histamine) of mast cells?

A
  • 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
Q

What is prophylaxis?

A
  • Provide protection
  • Prevent disease
  • To guard or prevent beforehand
73
Q

What is anaphylaxis?

A

Opposite of prophylaxis

-An acute allergic reaction to an antigen

74
Q

What is the function of IgD?

A

-Function is not completely clear
-A lot like IgM
B cells don’t make it until they leave the bone

75
Q

What controls class switching?

A

cytokines (T cells)

76
Q

What is passive immunoptherapy?

A

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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