Immunology Exam 3 Questions and
Correct Answers 2026 Question Bank
Which of the following is NOT a characteristic of a secondary humoral response to an
administered protein antigen?
It takes about 7 days to begin
The response can be 100 or 1000 times larger than the primary response
IgG is the most common antibody isotype produced
The antibody produced has a higher average affinity than that produced in the primary
response
Memory B-cells are activated and generate plasma cells - <CORRECT ANSWER >>It takes about
7 days to begin
Which of the following is required to induce allelic exclusion in heavy chain gene expression?
pre-B-cell receptor
pre-T alpha
CD3
CD3 and pre-T alpha
CD8 - <CORRECT ANSWER >>pre-B-cell receptor
The drug cyclosporin A inhibits calcineurin, what is it used for?
To block lymphocyte activation
To activate T-lymphocytes
To fight viral infections
To block protein loading into MHC class I molecules and to block lymphocyte activation
To block protein loading into MHC class I molecules - <CORRECT ANSWER >>To block
lymphocyte activation
,Which of the following molecules would NOT be expected to play a major role in initiating the
production of IgG directed against a protein antigen?
CD8
B7
Cytokines
MHC class II
CD40 - <CORRECT ANSWER >>CD8
What is the function of B7?
It is expressed by activated T-cells and receives the second activation signal from B-cells
It is expressed by naïve T-cells and receives the second activation signal from B-cells
It is expressed by activated B-cells and provides the second signal for T-cell activation
It is expressed by naïve T-cells and provides the second activation signal to B-cells
It is expressed by B-cells and receives the second activation signal from activated T-cells -
<CORRECT ANSWER >>It is expressed by activated B-cells and provides the second signal for T-
cell activation
Which of the following statements regarding interleukin-2 (IL-2) is correct?
The receptor for IL-2 is expressed on progenitor B-cells
IL-2 causes an activated T-cell to undergo clonal expansion
IL-2 is produced by T-cells after receiving the first signal for activation
IL-2 acts on T-cells after signal one and provides the second signal for activation
IL-2 is expressed by bone marrow stromal cells and acts on pro-B-cells - <CORRECT ANSWER
>>IL-2 causes an activated T-cell to undergo clonal expansion
Clonal expansion of T-cells occurs:
When interleukin-2 (IL-2) acts in an autocrine manner on cells with the IL-2 receptor
Following B-cell receptor binding to foreign antigen and self MHC molecules
,After B7 binding to CD28 on antigen presenting cells
Soon after the lymphoid progenitor arrives in the thymus
Following a signal through the pre-B-cell receptor - <CORRECT ANSWER >>When interleukin-2
(IL-2) acts in an autocrine manner on cells with the IL-2 receptor
Which of the following leads to a net increase in antibody affinity during humoral responses?
Interaction of B-cells with thymic epithelial cells
Recombination of germ line gene segments
Somatic hypermutation and interaction of B-cells with thymic epithelial cells
Isotype switching
Somatic hypermutation - <CORRECT ANSWER >>Somatic hypermutation
Which of the following statements is correct?
10% of developing B-cells survive positive selection
2% of developing T-cells survive negative selection
90% of developing T-cells survive negative selection
98% of developing T-cells survive positive selection
90% of developing B-cells survive negative selection - <CORRECT ANSWER >>2% of developing
T-cells survive negative selection
Which of the following events requires exposure to protein antigens?
B-cell affinity maturation and memory cell formation
Memory cell formation
B-cell affinity maturation
B-cell selection in the thymus
B-cell maturation in the bone marrow - <CORRECT ANSWER >>B-cell affinity maturation and
memory cell formation
, A cell that is present in the thymus that expresses CD3 but NOT a T-cell receptor beta chain on
its cell surface is most likely to be a:
Precursor B-cell
Thymic epithelial cell
Double negative T-cell
Double positive T-cell
Progenitor B-cell - <CORRECT ANSWER >>Double negative T-cell
Which of the following is NOT a characteristic of a primary humoral response to an
administered protein antigen?
Memory B-cells are activated and generate plasma cells and it takes about a week to begin
Memory B-cells are activated and generate plasma cells
Naïve B-cells are activated and generate plasma cells
IgM is the most common antibody isotype produced
It takes about a week to begin - <CORRECT ANSWER >>Memory B-cells are activated and
generate plasma cells
Which of the following statements is FALSE with regard to secondary responses to a protein
antigen?
The antibody isotype most commonly produced in the secondary response is IgM
The antibodies produced have a higher net affinity for that particular antigen
The response is larger because of the presence of many memory cells specific for that particular
antigen
The amount of antibody produced is many times greater than that made during the primary
response
The response is quicker because memory cells are more easily activated than naïve cells -
<CORRECT ANSWER >>The antibody isotype most commonly produced in the secondary
response is IgM
Which of the following can occur without T-cell help?
Correct Answers 2026 Question Bank
Which of the following is NOT a characteristic of a secondary humoral response to an
administered protein antigen?
It takes about 7 days to begin
The response can be 100 or 1000 times larger than the primary response
IgG is the most common antibody isotype produced
The antibody produced has a higher average affinity than that produced in the primary
response
Memory B-cells are activated and generate plasma cells - <CORRECT ANSWER >>It takes about
7 days to begin
Which of the following is required to induce allelic exclusion in heavy chain gene expression?
pre-B-cell receptor
pre-T alpha
CD3
CD3 and pre-T alpha
CD8 - <CORRECT ANSWER >>pre-B-cell receptor
The drug cyclosporin A inhibits calcineurin, what is it used for?
To block lymphocyte activation
To activate T-lymphocytes
To fight viral infections
To block protein loading into MHC class I molecules and to block lymphocyte activation
To block protein loading into MHC class I molecules - <CORRECT ANSWER >>To block
lymphocyte activation
,Which of the following molecules would NOT be expected to play a major role in initiating the
production of IgG directed against a protein antigen?
CD8
B7
Cytokines
MHC class II
CD40 - <CORRECT ANSWER >>CD8
What is the function of B7?
It is expressed by activated T-cells and receives the second activation signal from B-cells
It is expressed by naïve T-cells and receives the second activation signal from B-cells
It is expressed by activated B-cells and provides the second signal for T-cell activation
It is expressed by naïve T-cells and provides the second activation signal to B-cells
It is expressed by B-cells and receives the second activation signal from activated T-cells -
<CORRECT ANSWER >>It is expressed by activated B-cells and provides the second signal for T-
cell activation
Which of the following statements regarding interleukin-2 (IL-2) is correct?
The receptor for IL-2 is expressed on progenitor B-cells
IL-2 causes an activated T-cell to undergo clonal expansion
IL-2 is produced by T-cells after receiving the first signal for activation
IL-2 acts on T-cells after signal one and provides the second signal for activation
IL-2 is expressed by bone marrow stromal cells and acts on pro-B-cells - <CORRECT ANSWER
>>IL-2 causes an activated T-cell to undergo clonal expansion
Clonal expansion of T-cells occurs:
When interleukin-2 (IL-2) acts in an autocrine manner on cells with the IL-2 receptor
Following B-cell receptor binding to foreign antigen and self MHC molecules
,After B7 binding to CD28 on antigen presenting cells
Soon after the lymphoid progenitor arrives in the thymus
Following a signal through the pre-B-cell receptor - <CORRECT ANSWER >>When interleukin-2
(IL-2) acts in an autocrine manner on cells with the IL-2 receptor
Which of the following leads to a net increase in antibody affinity during humoral responses?
Interaction of B-cells with thymic epithelial cells
Recombination of germ line gene segments
Somatic hypermutation and interaction of B-cells with thymic epithelial cells
Isotype switching
Somatic hypermutation - <CORRECT ANSWER >>Somatic hypermutation
Which of the following statements is correct?
10% of developing B-cells survive positive selection
2% of developing T-cells survive negative selection
90% of developing T-cells survive negative selection
98% of developing T-cells survive positive selection
90% of developing B-cells survive negative selection - <CORRECT ANSWER >>2% of developing
T-cells survive negative selection
Which of the following events requires exposure to protein antigens?
B-cell affinity maturation and memory cell formation
Memory cell formation
B-cell affinity maturation
B-cell selection in the thymus
B-cell maturation in the bone marrow - <CORRECT ANSWER >>B-cell affinity maturation and
memory cell formation
, A cell that is present in the thymus that expresses CD3 but NOT a T-cell receptor beta chain on
its cell surface is most likely to be a:
Precursor B-cell
Thymic epithelial cell
Double negative T-cell
Double positive T-cell
Progenitor B-cell - <CORRECT ANSWER >>Double negative T-cell
Which of the following is NOT a characteristic of a primary humoral response to an
administered protein antigen?
Memory B-cells are activated and generate plasma cells and it takes about a week to begin
Memory B-cells are activated and generate plasma cells
Naïve B-cells are activated and generate plasma cells
IgM is the most common antibody isotype produced
It takes about a week to begin - <CORRECT ANSWER >>Memory B-cells are activated and
generate plasma cells
Which of the following statements is FALSE with regard to secondary responses to a protein
antigen?
The antibody isotype most commonly produced in the secondary response is IgM
The antibodies produced have a higher net affinity for that particular antigen
The response is larger because of the presence of many memory cells specific for that particular
antigen
The amount of antibody produced is many times greater than that made during the primary
response
The response is quicker because memory cells are more easily activated than naïve cells -
<CORRECT ANSWER >>The antibody isotype most commonly produced in the secondary
response is IgM
Which of the following can occur without T-cell help?
