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SAC Microbiology > Lecture 11 > Flashcards

Lecture 11 Flashcards

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1
Q

What event occurs after the binding of a CD40 protein on a B cell to a CD40 ligand on a T cell?

A) internalization of antigen bound by B-cell receptors
B) release of perforins and granzymes from the T cell
C) release of IL-4 and IL-6 from the T cell
D) initiation of heavy chain class switching in the B cell.

A

D) initiation of heavy chain class switching in the B cell

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2
Q

Which two events are required to activate a cytotoxic T cell?

A. IL-2 is released by a TH1 cell to be bound by a cytotoxic T cell.
B. Class I MHC molecules presents intracellular antigen for binding on a complementary cytotoxic T cell receptor.
C. IL-4 is released by a TH1 cell to be bound by a cytotoxic T cell.
D. Class II MHC molecules present extracellular antigen for binding on a complementary cytotoxic T cell receptor

A

A. IL-2 is released by a TH1 cell to be bound by a cytotoxic T cell.

B. Class I MHC molecules presents intracellular antigen for binding on a complementary cytotoxic T cell receptor.

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3
Q

Which of the following is the most antigenic?

A) Lipids
B) Carbohydrates
C) Nucleic acids
D) Proteins

A

D) Proteins

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4
Q

____ are the strongest antigens because they form a variety of shapes, they maintain tertiary structures, and they are made of amino acids in different combinations

A

Proteins

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5
Q

____ and ____ tend to be weaker antigens because they are more flexible and their subunits are relatively uniform.

A

Lipids; nucleic acids

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6
Q

All (nucleated) cells in a human body normally have:

A) Class I MHC molecules.
B) Class II MHC molecules.
C) CD8 surface antigens.
D) CD4 surface antigens.

A

A) Class I MHC molecules.

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7
Q

Class ____ molecules are found on the surface of all nucleated cells

A

I MHC

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8
Q

Class ____ molecules are found on the surface of antigen-presenting cells (dendritic cells, macrophages, and B cells)

A

II MHC

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9
Q

MHC molecules are used to present ____ to ____ cells.

A

antigen; T

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10
Q

Breast milk and colostrum provide passive immunity to infants in the form of ______. Hint: mucosal antibodies

A) IgE
B) IgG
C) IgM
D) IgA

A

D) IgA

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11
Q

____ is secreted across mucosal surface and is found in tears, breast milk, and saliva.

A

IgA

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12
Q

____ immunity occurs when babies receive IgG through the placenta and IgA through breast milk.

A

Passive

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13
Q

In which of the following scenarios would you expect capping to occur?

A) A B-cell contacts a soluble protein with many different epitopes.
B) A T-cell recognizes antigen bound to the surface of an antigen-presenting cell.
C) A B-cell contacts a microbe with multiple copies of the same epitope.
D) A T-cell recognizes antigen bound to the surface of a B-cell.

A

C) A B-cell contacts a microbe with multiple copies of the same epitope.

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14
Q

____ occurs when adjacent B-cell receptors bind adjacent epitopes on a microbe

A

Capping

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15
Q

Capping is ____ cell independent and leads to activation of the ____ cell.

A

T, B

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16
Q

Jamal is vaccinated against varicella, also known as chicken pox, as a young child. If he has subsequent exposure to the varicella virus as an adult, what would you expect to occur?

A) He would rapidly secrete much higher levels of IgM than he did after vaccination.
B) Class switching would lead to a switch from IgG production to IgM production.
C) He would develop varicella because vaccines only stimulate low levels of antibodies.
D) His titer levels of IgG would be much higher than they were after vaccination.

A

D) His titer levels of IgG would be much higher than they were after vaccination.

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17
Q

Vaccination stimulates a ____ immune response.

A

primary

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18
Q

During a secondary immune response, subsequent exposure would lead to class switching from ____ production to ____ production

A

IgM; IgG

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19
Q

During a secondary immune response, ____ antibodies would be secreted at much higher levels.

A

IgG

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20
Q

Patients who have functioning T cells but dysfunctional B cells will retain:

A) the ability to produce plasma cells.
B) cell-mediated immunity.
C) the ability to produce antibodies.
D) humoral immunity.

A

B) cell-mediated immunity.

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21
Q

____ cells are responsible for the production of antibodies during a humoral immunity response

A

B

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22
Q

The specific cells that secrete antibodies are differentiated B cells known as ____ cells.

A

plasma

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23
Q

____ cells are responsible for cell-mediated immunity.

A

T

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24
Q

T cells capable of activating cytotoxic T cells are known as ______.

A) TH2 cells
B) TH0 cells
C) TH1 cells
D) Treg cells

A

C) TH1 cells

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25
Q

The major function of TH1 cells is activation of ____.

A

cytotoxic T cells

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26
Q

The major function of Treg cells is ____.

A

anti-inflammatory

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27
Q

The major function of TH2 cells is ____.

A

helping B cells

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28
Q

The major function of TH0 cells is differentiation into ____.

A

TH1 or TH2 cells

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29
Q

The binding of the T-cell receptor (TCR) of a TH0 cell to an antigen-MHC complex is not enough to activate the TH0 cell. A second activation signal involves an interaction between:

A) a CD40 molecule on the T cell and a CD4 molecule on the antigen-presenting cell.
B) a CD28 molecule on the T cell and a B7 molecule on the antigen-presenting cell.
C) a B7 molecule on the T cell and a CD28 molecule on the antigen-presenting cell.
D) a CD4 molecule on the T cell and a CD40 molecule on the antigen-presenting cell.

A

B) a CD28 molecule on the T cell and a B7 molecule on the antigen-presenting cell.

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30
Q

Two interactions must occur for TH0 cells to become activated. The first interaction involves linking a T-cell receptor to an ____ on antigen-presenting cell (APC). The second interaction involves linking a ____ to a B7 protein on the APC surface.

A

antigen-MHC II complex; CD28 on the T-cell surface

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31
Q

The step leading directly to the binding of CD40 and CD40 ligand is ____.

A

the binding of a T-cell receptor to an antigen-MHC II complex on a B-cell

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32
Q

What is the first molecular signal required for TC cell activation?

A) secretion of the cytokine IL-2 from a TH1 cell
B) binding of a T-cell receptor to an antigen-MHC I complex on an antigen-presenting cell
C) secretion of the cytokine IL-1 from a TH0 cell
D) binding of a CD28 molecule on the T cell to a B7 protein on an antigen-presenting cell

A

B) binding of a T-cell receptor to an antigen-MHC I complex on an antigen-presenting cell

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33
Q

Two molecular signals are required for activation of Tc cells. The first signal involves binding of the ____. CD8 molecules on the Tc cell allow this binding to class I MHC on the APC occur. The second signal is the secretion of the ____.

A

T-cell receptor (TCR) to an antigen-presenting cell (APC); cytokine IL-2 from TH1 cells.

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34
Q

Which of the following is considered a “professional” antigen-presenting cell (APC)?

A) epithelial cell
B) fibroblast
C) macrophage
D) chondrocyte

A

C) macrophage

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35
Q

Macrophages, dendritic cells, mast cells, and B cells are considered ____.

A

“professional” APCs.

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36
Q

Antibodies are produced by _____.

a. plasma cells
b. T cells
c. bone marrow
d. Macrophages

A

a. plasma cells

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37
Q

Cellular adaptive immunity is carried out by
______.

a. B cells
b. T cells
c. bone marrow
d. neutrophils

A

b. T cells

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38
Q

single antigen molecule may be composed of many individual _____.

a. T-cell receptors
b. B-cell receptors
c. MHC II
d. epitopes

A

d. epitopes

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39
Q

Which class of molecules is the most antigenic?

a. polysaccharides
b. lipids
c. proteins
d. carbohydrates

A

c. proteins

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40
Q

MHC I molecules present ____.

a. processed foreign antigens from
proteasomes.
b. processed self-antigens from
phagolysosome.
c. antibodies.
d. T cell antigens.
A

a. processed foreign antigens from

proteasomes.

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41
Q

MHC II molecules present ____.

a. processed self-antigens from proteasomes.
b. processed foreign antigens from
phagolysosomes.
c. antibodies.
d. T cell receptors.

A

b. processed foreign antigens from

phagolysosomes.

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42
Q

Which type of antigen-presenting molecule is found on all nucleated cells?

a. MHC II
b. MHC I
c. antibodies
d. B-cell receptors

A

b. MHC I

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43
Q

Which type of antigen-presenting molecule is found only on macrophages, dendritic cells, and B cells?

a. MHC I
b. MHC II
c. T-cell receptors
d. B-cell receptors

A

b. MHC II

44
Q

What is a superantigen?

a. a protein that is highly efficient at
stimulating a single type of productive and specific T cell response
b. a protein produced by antigen-presenting cells to enhance their presentation capabilities
c. a protein produced by T cells as a way of increasing the antigen activation they receive from antigen-presenting cells
d. a protein that activates T cells in a
nonspecific and uncontrolled manner

A

d. a protein that activates T cells in a

nonspecific and uncontrolled manner

45
Q

To what does the TCR of a helper T cell bind?

a. antigens presented with MHC I molecules
b. antigens presented with MHC II molecules
c. free antigen in a soluble form
d. haptens only

A

b. antigens presented with MHC II molecules

46
Q

Cytotoxic T cells will bind with their TCR to
which of the following?

a. antigens presented with MHC I molecules
b. antigens presented with MHC II molecules
c. free antigen in a soluble form
d. haptens only

A

a. antigens presented with MHC I molecules

47
Q

Name the T helper cell subset involved in
antibody production.

a. TH1
b. TH2
c. TH17
d. CTL

A

b. TH2

48
Q

Which of the following would be a T-dependent antigen?

a. lipopolysaccharide
b. glycolipid
c. protein
d. carbohydrate

A

c. protein

49
Q

A patient is bitten by a dog with confirmed rabies infection. After treating the bite wound, the physician injects the patient with antibodies that are specific for the rabies virus to prevent the development of an active infection. This is an example of:

a. Natural active immunity
b. Artificial active immunity
c. Natural passive immunity
d. Artificial passive immunity

A

d. Artificial passive immunity

50
Q

A patient gets a cold, and recovers a few days later. The patient’s classmates come down with the same cold roughly a week later, but the original patient does not get the same cold again. This is an example of:

a. Natural active immunity
b. Artificial active immunity
c. Natural passive immunity
d. Artificial passive immunity

A

a. Natural active immunity

51
Q

This class of antibody is the only one that can cross the placenta

A

IgG

52
Q

This class of antibody is the first to appear after activation of B cells

A

IgM

53
Q

This class of antibody is involved in the defense against parasitic infections and involved in allergic responses

A

IgE

54
Q

This class of antibody is found in very large amounts in mucus secretions

A

IgA

55
Q

This class of antibody is not secreted by B cells but is expressed on the surface of naïve B cells

A

IgD

56
Q

There are two critically important aspects of adaptive immunity. The first is specificity, while the second is _____.

A

Memory

57
Q

____ immunity involves the production of
antibody molecules that bind to specific
antigens.

A

Humoral

58
Q

The heavy chains of an antibody molecule
contain _____ region segments, which help
to determine its class or isotype.

A

Constant

59
Q

The variable regions of the heavy and light chains form the _____ sites of an antibody.

A

Antigen-binding

60
Q

MHC molecules are used for antigen _____ to T cells.

A

Presentation

61
Q

A _____ T cell will become activated by

presentation of foreign antigen associated with an MHC I molecule

A

Cytotoxic

62
Q

A ____T cell will become activated by presentation of foreign antigen in association with an MHC II molecule.

A

Helper

63
Q

Both ____ and effector T cells are produced during differentiation of activated T cells

A

Memory

64
Q

____ antigens can stimulate B cells to
become activated but require cytokine
assistance delivered by helper T cells.

A

T-dependent

65
Q

____ immunity occurs when antibodies
from one individual are harvested and given to
another to protect against disease or treat active
disease.

A

Artificial passive

66
Q

Adaptive immunity is an acquired defense

against foreign pathogens that is characterized by ____ and ____.

A

specificity and memory

67
Q

Adaptive immunity is a dual system involving ____ immunity (antibodies produced by B cells) and ____ immunity (T cells directed against intracellular pathogens).

A

humoral; cellular

68
Q

A single antigen possesses smaller ____, each capable of inducing a specific adaptive immune response.

A

epitopes

69
Q

____ is a collection of genes coding for glycoprotein
molecules expressed on the surface of all
nucleated cells.

A

Major histocompatibility complex (MHC)

70
Q

____ molecules are expressed on all nucleated cells and are essential for presentation of normal “self” antigens.

A

MHC I

71
Q

____ molecules are expressed only on the
surface of antigen-presenting cells
(macrophages, dendritic cells, and B cells).

A

MHC II

72
Q

____ cells primarily ingest pathogens by phagocytosis

A

Antigen-presenting cells (APCs)

73
Q

____ cells differentiate into TH1, TH2, TH17, or memory T cell subtypes.

A

Activated helper T cells

74
Q

B lymphocytes or B cells produce antibodies involved in ____ immunity.

A

humoral

75
Q

Protein antigens are called ____ antigens because they can only activate B cells with the cooperation of helper T cells.

A

T-dependent

76
Q

All nucleated cells in a human body normally have ____ molecules.

A

Class I MHC

77
Q

What is the first molecular signal required for Tc activation?

A) secretion of the cytokine IL-2 from a TH1 cell
B) secretion of the cytokine IL-1 from a TH0 cell
C) binding of a T-cell receptor to an antigen–MHC I complex on an antigen-presenting cell
D) binding of a CD28 molecule on the T cell to a B7 protein on an antigen-presenting cell

A

C. binding of a T-cell receptor to an antigen–MHC I complex on an antigen-presenting cell

78
Q

A child receives her first diphtheria vaccine when she is 5 years old. Four weeks later she receives a booster dose. One week later her physician checks her serum titer. Which of the following would indicate a normal response?

A) Elevated levels of both IgM and IgG
B) IgG levels near zero and elevated IgM
C) Low levels of both IgG and IgM
D) IgM levels near zero and elevated IgG

A

A) Elevated levels of both IgM and IgG

79
Q

Lymphocytes that are capable of killing infected host cells are known as____.

A

Cytotoxic T cells

80
Q

The second signal required for T cell activation is ____.

A) secretion of the cytokine IL-2 from a TH1 cell.
B) binding of a CD8 molecule on the T cell to an antigen-MHC I complex on an antigen-presenting cell.
C) secretion of the cytokine IL-1 from a TH0 cell.

A

B. binding of a CD8 molecule on the T cell to an antigen-MHC I complex on an antigen-presenting cell.

81
Q

How are antigens processed before binding to MHC class I molecules?

A.They are digested in the cytoplasm of the cell by the proteosome.
B. they are digested by enzymes in the endoplasmic reticulum.
C.They are digested by enzymes in the endocytic vesicle.

A

C.They are digested by enzymes in the endocytic vesicle.

82
Q

The following are the steps for B-cell activation. The steps are in an incorrect order.

  1. B cells display antigens in MHC class II receptors on the cell surface.
  2. Antibodies released by plasma cells bind to antigen so they will be destroyed by other cells of the immune system.
  3. B cells rearrange their DNA to create a unique B-cell receptor.
  4. B cells become activated by interacting with helper T cells.
  5. B cells undergo clonal expansion.
  6. B cells digest antigens that bind to the antibodies on their surface.
A

3, 6, 1, 4, 5, 2

83
Q

Both MHC class I receptors and MHC class II receptors are synthesized on the rough ER. What keeps MHC class II receptors from binding to antigens while in the ER?

a) The MHC class II receptor has its binding site covered by a protein called the invariant chain. Until that is removed, it is unable to bind to any antigens.
b) There are no antigens in the ER compartment for MHC class II to bind.
c) The MHC class II molecules are kept in a separate compartment of the ER so that they cannot mix with antigens yet.
d) Any antigens bound to the MHC class II molecule are removed by enzymes in the Golgi complex.

A

a) The MHC class II receptor has its binding site covered by a protein called the invariant chain. Until that is removed, it is unable to bind to any antigens.

84
Q

What cytokine directs a cytotoxic response?

A

IL-2

85
Q

What occurs after a B cell binds to an epitope?

A

Clonal expansion of the activated B cell

86
Q

Why are lipids less immunogenic than proteins?

A

Lipids are more flexible than proteins.

87
Q

What is an APC?

A

Only macrophages, dendritic cells, & B lymphocytes have the ability to present antigens with the specific purpose of activating T lymphocytes

88
Q

Th (CD4) functions

A
  1. Orchestrate humoral and cellular immunity
  2. Involved in the activation of macrophages and NK cells
  3. Formation of Tc cells, activate macrophages, produce cytokines, & formation of antibodies by B cells
89
Q

Tc (CD8) function

A

Destroy cells infected with INtracellular pathogens

90
Q

Th1 cell function

A

Stimulate cytotoxic T cells and produce memory cytotoxic T cells

Stimulate macrophages and NK cells

91
Q

Th2 function

A

Stimulate B cell activation and differentiation into plasma cells and memory B cells

92
Q

Tc cell function

A

Differentiate into effector cytotoxic T cells that target pathogens for destruction or memory cells

93
Q

CD4 only interacts with MHC __.

A

MHC II

94
Q

IgG Fc binds to ____.

A

Phagocytes

95
Q

IgG functions

A

Neutralization, agglutination, complement activation, & opsonization

96
Q

IgM shape

A

Pentamer

97
Q

IgM functions

A

Neutralization, agglutination, & complement activation

98
Q

IgA function

A

Neutralization & trapping of pathogens in mucus

99
Q

IgD function

A

B cell receptor

100
Q

IgE function

A

Binds to basophils & mast cells against parasites and allergens

101
Q

Th (CD4) activated by MHC __.

A

MHC II

102
Q

Treg activated by MHC __.

A

MHC II

103
Q

Tc (CD8) activated by MHC __.

A

MHC I

104
Q

Tc (CD8) cells focus on INtracellular or EXtracellular infections?

A

INtracellular

105
Q

What immunoglobulins are present on the surface of naive B cells?

A

IgM and IgD

106
Q

All cells have MHC __ and therefore any cell can be killed by Tc cells.

A

MHC I

SAC Microbiology (19 decks)

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