MCQ Immunology 1

Question 1

The principal developmental organ of T cells corresponds to the

A.Thymus

B.Bone Marrow

C.Both options A and B are correct

D.None of the above

Answer 1

A.Thymus

Question 2

During positive selection, interactions between immature T cell receptor and self MHC:

A.Is favorable, as it ensures the compatibility necessary for antigen presentation

B.Results in T cell apoptosis

C.Prevents the development of autoimmiunity

D.None of the above as only mature T cells undergo positive selection

Answer 2

A.Is favorable, as it ensures the compatibility necessary for antigen presentation

Question 3

During negative selection, a strong interaction between an immature T cell receptor and self-peptide:

A.Is favourable, as it ensures that antigens presented in the context of MHC are recognised by T cells

B.Rescues the T cell from programmed cell death (apoptosis)

C.Results in T cell migrating to the periphery

None of the above

Answer 3

none

Question 4

Immunological tolerance in T cells:

A.Only occurs in the thymus after immature T cells migrate from the bone marrow

B.Promotes autoimmunity and so causes destruction of tissues and organs

C.Because T cells that recognise self-antigens from apoptosis

D.Also involves deletion/deactivation of T cells in the thymus and periphery

Answer 4

D.Also involves deletion/deactivation of T cells in the thymus and periphery

Question 5

T cells that have αβ T cell receptors:

A.Do not express CD4+ or CD8+ or CD3+

B.Constitute 98% (i.e. most) of the total T cell population

C.Do not require MHC molecules to interact with antigens

D.Are not involved in adaptive immune responses as they are innate immune cells

Answer 5

B.Constitute 98% (i.e. most) of the total T cell population

Question 6

T cells that express γ and δ chains of the T cell receptor:

A.Have ‘innate-like’ immune function

B.Express either CD4+ or CD8+

C.Undergo extensive gene rearrangements

D.Have diverse immunoglobulin repertoires and are highly migratory

Answer 6

A.Have ‘innate-like’ immune function

Question 7

The CD3 component of the T cell receptor complex is involved in:

A.Recognising antigenic peptides associated to MHC complexes

B.Signal transduction via phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMS)

C.Direct interaction with MHCII and MHCI molecules

D.Permits the initial interaction between a T cell and the antigen presenting cell

Answer 7

B.Signal transduction via phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMS)

Question 8

CD4+ T cells:

A.Recognise antigenic peptides presented in context of MHCII

B.Recognise antigenic peptides produced by proteasome processing

C.Recognise MHCI molecules on most nucleated cells

D.Are also known as cytotoxic T cells

Answer 8

A.Recognise antigenic peptides presented in context of MHCII

Question 9

CD8 co-receptors:

A.Are expressed on helper T cells and interact with MHCII molecules

B.Are mainly responsible for signal transduction after the T cell binds antigen

C.Are expressed on cytotoxic T cells and interact with MHCI molecules

D.Are used to identify T helper cells in flow cytometry experiments

Answer 9

C.Are expressed on cytotoxic T cells and interact with MHCI molecules

Question 10

Which of the following statements regarding αβ T cell receptor gene rearrangement is true

A.α chains gene rearrangement continues after the process of positive selection is complete and prevents apoptosis of the maturing T cells

B.The pre-Tcell receptor is only found on the double positive thymocytes right after productive of α chain rearrangement, but before productive β chain rearrangement

C.By comparison to the light chains of immunoglobulins, the likelihood of rescue by successful gene rearrangement of the α chain and β chain is decreased

D.Failure of the T cell to make productive gene rearrangements of both the α chain and β chains

Answer 10

D.Failure of the T cell to make productive gene rearrangements of both the α chain and β chains

Question 11

The following statement correctly describes a common feature of T & B cell development:

A.A single progenitor cell gives rise to lymphocytes of identical specificity

B.T and B cells undergo stepwise rearrangement of antigen receptor genes

C.Each lymphocyte can express antigen recognition receptors with multiple specificities

D.Both undergo negative selection, such that self-reactive lymphocytes are abundant in the repertoire of mature lymphocytes

Answer 11

B.T and B cells undergo stepwise rearrangement of antigen receptor genes

Question 12

A naïve lymphocyte is:

A.A mature lymphocyte that is yet to encounter its specific antigen

B.A lymphocyte that can become activated once it encounters its specific antigen and undergoes co-stimulation

C.Both options a & b are correct

D.Neither a nor b are correct

Answer 12

C.Both options a & b are correct

Question 13

Developing T cells first express pre-T cell receptors:

A.At the double positive T cell stage

B.After negative selection

C.When they are both double negative lymphocytes

D.After positive selection

Answer 13

C.When they are both double negative lymphocytes

– At this stage they become γ:δ or α:β

Question 14

Mature α:β T cells:

A.Are exported to the periphery

B.Are double positive for CD4+/CD8+

C.Express CD3

D.Options a & c are correct

Answer 14

A.Options a & c are correct

For option B) Mature T cells are CD4+ or CD8+ only

Question 15

The expression of γ:δ T cell receptor results in lymphocytes with ‘innate like’ features, an example of which is that these cells:

A.Recognise unorthodox nucleotides in the context of MHC molecules

B.Do not undergo clonal expansion

C.Have a range of effector functions

D.Have a completely different structice to α:β cell receptors

Answer 15

Answer: Do not undergo clonal expansion

A)Antigen presentation to these cells is MHC dependent

C) Characteristic of α:β T cells

D) Both receptors are structurally similar

Question 16

Which of the options below does not describe α:β T cell receptor rearrangement:

A.TcR rearrangement is recombination activating genes (RAG)-1 & 2 independent

B.Α chain rearrangement continues until either a productive rearrangement leads to positive selection or the cell dies

C.Genes encoding the β chain have D, V and J segments

D.The α chain has an increased likelihood of rescue because of multiple successive rearrangement events

Answer 16

A.TcR rearrangement is recombination activating genes (RAG)-1 & 2 independent

Both RAG-1 & 2 are required

Question 17

Which of the statements below is incorrect?

A.Activated dendritic cells migrate from tissues to lymphatic vessels in order to reach the lymph nodes

B.Within lymph nodes T cells inspect antigens presented by dendritic cells

C.T cells that become activated exist the lymph node to start proliferating in the blood

D.Activated T cells differentiate to become effector cells which can exit the lymph node

Answer 17

C.T cells that become activated exist the lymph node to start proliferating in the blood

Answer: C – Activated T cells start proliferating and lose the abilirty to exit the lymph node

Question 18

Which of the statements below is true for co-stimulatory molecules?

A.They mediate the initial interaction between naïve T cells and antigen presenting cells

B.They stimulate the expression of additional co-stimulatory molecules by the antigen presenting cell and induce survival and expansion of the T cell

C.They decrease the production of IL-2, thus promoting T cell expansion and differentiation into effector cells

D.The t cell receptor and co-stimulatory molecules interact with the MHC peptide complex

Answer 18

A.They stimulate the expression of additional co-stimulatory molecules by the antigen presenting cell and induce survival and expansion of the T cell

Question 19

Which of the following statements regarding immunological synapse is incorrect?

A.It is comprised of the secretory domains, adhesion zone and signalling domain

B.It facilitates the confinement and concentration of effector molecules released by activated T cells

C.It enables the exocytosis of perforins and granzymes which prevent apoptosis

D.Its formation leads to the activation of signalling pathways that induce gene transcripton

Answer 19

Answer: C – It enables the exocytosis of perforins and granzymes which prevent apoptosis

The transport perforin and granzymes to the immunological synapse are delivered to the target cell to induce cell death

Question 20

CD8+ T cell activation required CD4+ T cell help because

A.This acts as a mechanism of regulation to prevent uncontrolled cytotoxicity that could negatively impact healthy cells

B.CD4+ T cells sequester the IL-2 produced CD8+ T cells as a regulatory mechanism

C.CD4+ T cells reduce the levels of co-stimulatory activity in the antigen presenting cell which avoids excessive activation of the CD8+ T cells

D.All of the above are correct

Answer 20

A.This acts as a mechanism of regulation to prevent uncontrolled cytotoxicity that could negatively impact healthy cells

Answer: A

B) Interaction with APCs cells induces CD40L and IL-2 in CD4+ T cells, IL-2 can bind to IL-2 receptors on the surface of CD8+ T cells that are also interacting with the same APC, further stimulating their activation

C) Interactive between CD40 on APCs and CD40L on CD4+ T cells, increases expression of B7 and 4-IBBL on the APC surface, which co-stimulated naïve CD8+ T cells

Question 21

T cells are capable of instant immune attack when they are:

A.Naïve

B.Immature thymocytes

C.Effector T cells

D.None of the above, T cells are never capable of instant immune attack

Answer 21

A.Effector T cells

Answer: C – Effector T cells are capable of performing their cytotoxic, helper or regulatory functions without requiring co-stimulation

Question 22

The major difference between CD8+ T cells and natural killer (NK) cell cytotoxicity

A.Only NK cells induce target cell death by apoptosis

B.CD8+ T cells only kill host cells infected with intracellular bacteria

C.NK cells only use perforins and granzymes to induce cytotoxicity

D.Cytotoxic T cells recognise virus-infected cells by recognising viral antigens on the surface of the target cell

Answer 22

D. Cytotoxic T cells recognise virus-infected cells by recognising viral antigens on the surface of the target cell

– NK cells being innate immune cells do not recognise specific antigen

Question 23

Granzymes induce apoptosis by which of the following downstream effector pathways

A.Activation of caspase 8 and subsequently downstream effector caspases, such as caspase -3 and -10

B.Activation of Bid by active caspase 8

C.Mitochondrial cell death pathway

D.All of the above options are correct

Answer 23

D.All of the above options are correct

Question 24

T helper cells

A.Express CD8+ on their surface

B.Control the expansion and differentiation of T cells and B cells

C.Are the main inducers of controlled cell death of virally infected host cells

D.Cannot activate innate immune cells

Answer 24

D.Cannot activate innate immune cells

Question 25

Which of the following cytokines are mainly secreted by CD4 T helper 2 cells A.IL-2, IL-3 and TNF-α B.IL-6, TGF-β and IL-17 C.IL-4, IL-5 and IL-13 D.All of the above

Answer 25

C.IL-4, IL-5 and IL-13 ## Footnote Answer: C – These cytokines are mainly secreted by Th2 cells

Question 26

As a mechanism of attack against extracellular bacteria and fungi, Th17 cells mediate the recruitment and stimulation of which type of innate immune cell A.Natural Killer cells B.Eosinophils C.Basophils D.Neutrophils

Answer 26

D.Neutrophils Answer: D – The IL-17 cytokine family secreted by Th17 cells induce chemokine production by local epithelial and stromal cells, these chemokines induce neutrophil recruitment at the early stages of the adaptive immune response

Question 27

The major role of helping B cells to produce antibodies of high affinity by the dual ability of secreting either Th1 or Th2 cytokines is characteristic of which type of T cell A.TFH cells B.TH1 cells C.TREG cells D.TH2 cells

Answer 27

Answer: A – TFH provide help to B cells for high affinity antibody production in lymphoid follicles and germinal centres

Question 28

Which of the statements below correctly describe the function of CTLA-4 A.Is a structural analogue of co-stimulatory molecules B7 B.Is a receptor expressed on the surface of activated T cells that binds B7 with 20x more avidity than CD28 C.Is a receptor expressed on the surface of antigen presenting cells that binds b7 with 20x more avidity than CD28 D.Associated with its ligand enhances T cell activation

Answer 28

B.Is a receptor expressed on the surface of activated T cells that binds B7 with 20x more avidity than CD28 Answer: B - Activated T cells express CTLA-4 which competes with CD28 for binding to B7

Question 29

The biological action(s) of the cytokine IL-2 include A.Mediation of T cell expansion and differentiation into effector and memory cells B.Inhibition of TREG development and survival C.Mediation of NK cell proliferation and enhancement of their cytotoxic functions D.Options A and C are correct

Answer 29

D.Options A and C are correct ## Footnote Answer: D B) IL-2 is critical for the development of effector T cells, including TREGS

Question 30

A proposed mechanism of suppression by which TREG may cause T cell metabolic disruption is A.CD25 mediated target cell-deprivation of cytokines causing apoptosis B.Inhibition of target cell maturation by binding of LAG3 and MHCII C.Release of granzyme A or B by the TREG which induces apoptosis of target T cells D.All of the above options are correct

Answer 30

Answer: A – It has been proposed that the high surface expression of CD25 by TREG, a.k.a. IL-2 receptor α, may deprive actively dividing neighbouring T cells from the IL-2 they require, inducing their apoptosis

Question 31

The induction of regulatory T cells (TREGS) would potentially be of therapeutic benefit for the treatment of A.Cancer B.Cancer and autoimmune disease C.Infectious disease D.Autoimmune disease

Answer 31

Answer: D – Tregs can inhibit T cell responses, including those against auo(self)-antigens

Question 32

Which of the following statements regarding the activation of cytotoxic T cells is incorrect? A.CD28 on the T cell binds B7 (CD80/86) on the antigen presenting cell (APC) B.CD28 on the T cell binds CTLA4(CD152) on the APC C.Fas ligand on the activated T cell binds Fas on the target cell to induce apoptosis of the target cell D.IL-2 secreted by the T cell act in an autocrine manner

Answer 32

Answer: B – CD28 and CTLA-4 both bind to B7, the co-stimulatory molecules on antigen presenting cells. So they both compete for the same binding partner

Question 33

The immunological phenomenon by which an individual’s T cells respond to antigen bound to specific MHC allele expressed by that individuals (i.e. self MHC) is known as A.MHC restriction B.Allelic exclusion C.Immune tolerance D.Somatic hypermutation

Answer 33

Answer: A B) This term refers to the expression of one allele over the corresponding allele C) This is the deletion of induction of anergy in B and T cells D) This term refers to point mutations that occur in the BcR to fine tune antibody specificity

Question 34

A rabbit is immunised with a protein antigen for the first time and subsequently the spleen is removed and T cells isolated. The protein antigen is incubated in vitro with the isolated T cells and 24 hours later levels of interleukin (IL)-2 in the supernatant (i.e. secreted IL-2) are measured. Which is the most likely result? A.IL-2 levels will be high as memory T cells will be activated B.IL-2 levels will be low as T cells do not respond to soluble, native proteins C.IL-2 levels will be low as the T cells will be tolerised to the antigen after the first immunisation D.IL-2 levels will be low as the T cells are only found in lymph nodes and are not present in the spleen

Answer 34

Answer: B A)An increase in IL-2 levels would require activation of the T cells and T cells do not recognise soluble, native unprocessed antigens C) T cells require antigen to be presented to them by MHC molecules D) T cells are found at both of these sites they are secondary lymphoid organs

Question 35

Which of the following would be the most likely consequence of a mutation that resulted in the production of non-functional recombination activating gene (RAG) protein? A.An immunodeficiency syndrome characterised by T cell defects due to an inability to rearrange T cell receptor genes only B.An immunodeficiency syndrome due to an inability to rearrange both T cell and B cell receptor genes C.The generation of T cell receptors and B cell receptors with a single antigen specificity due to the inability to rearrange gene segments D.An immunodeficiency syndrome characterised by B cell defects due to an inability to rearrange T cell receptor genes only

Answer 35

Answer: B A)RAG is required for the rearrangement of both B cell and T cell gene segments C) BcRs and TcRs cannot be generated and so the carrier would have severe combined immunodeficiency D) RAG is required for the rearrangement of both B cell and T cell gene segments

Question 36

Which of the following statements is true for co-stimulatory molecules? A.They mediate the initial interaction between naïve T cells and antigen presenting cells B.They stimulate the expression of additional co-stimulatory molecules by the antigen presenting cell and induce survival and expansion of the T cell C.They decrease the production of IL-2, thus promoting T cell expansion and differentiation into effector cells D.The T cell receptor and co-stimulatory molecules interact with the MHC:peptide complex

Answer 36

Answer: B A)This is the role of cell adhesion molecules C) The most important function of co-stimulation is that interaction between CD80/CD86 with CD28 increases IL-2 production via NK-kB activation/translocation and increase IL-2 mRNA stability which drives clonal expansion and T cell differentiation D) It is the TcR and co-receptor molecules that interact with the MHC:peptide complex

Question 37

1. Which of the following innate immune response statements is false? a. Surface receptors of innate immune cells recognise pathogen associated molecular patterns. b. Results in the production of pathogen-specific antibodies and long term memory. c. Innate immunity enables rapid/immediate responses to invading pathogens. d. Includes internal defences such as phagocytosis of invading pathogens by innate immune cells.

Answer 37

b. Results in the production of pathogen-specific antibodies and long term memory.

Question 38

2. Which of the following statements is true for antimicrobial peptides (AMP)? a. Enhance phagocytosis. b. Preferentially bind eukaryotic membranes. c. Perforate bacterial membranes to induce lysis. d. Enhance phagocytosis and preferentially bind eukaryotic membranes.

Answer 38

Perforate bacterial membranes to induce lysis.

Question 39

3. Which of the following statements is specific to gut chemical barriers? a. Specialized enzymes such as pepsin. b. Antimicrobial peptides. c. Lysozymes. d. None of the above.

Answer 39

a. Specialized enzymes such as pepsin.

Question 40

4. Which complement pathway becomes activated by spontaneous hydrolysis of C3? a. Classical b. Alternative c. Lectin d. Both options a & b are correct

Answer 40

b. Alternative

Question 41

5. Complete the following sentence. The cleavage of C3 and C5 results in the production of C3a and C5a fragments which are....... a. fundamental for the establishment of the membrane attack complex (MAC). b. inactive molecules. c. opsonizing agents. d. Anaphylatoxins.

Answer 41

c. opsonizing agents.

Question 42

6. Which of the following statements is true for Neutrophils? a. Emigrate to tissues and become resident neutrophils with specialised functions. b. Are the most abundant white blood cell (WBC) in peripheral blood. c. Are the most efficient antigen presenting immune cell (APC). d. Kill virally infected host cells by forming pores in their extracellular membrane.

Answer 42

b. Are the most abundant white blood cell (WBC) in peripheral blood.

Question 43

7. Which of the innate immune cells below are not phagocytic? a. Lymphocytes b. Neutrophils c. Dendritic cells d. Macrophages

Answer 43

a. Lymphocytes

Question 44

8. Which of the following statements best describes the classical complement pathway effector function? a. Inflammation. b. Pathogenic lysis. c. Opsonisation. d. All of the above

Answer 44

d. All of the above

Question 45

9. Which complement component is involved in all complement pathways? a. C9 b. C3 c. C1q d. C4

Answer 45

b. C3

Question 46

10. Which of the following options best describes an opsonising agent? a. Surfactants b. Antibodies c. C3b d. All of the above

Answer 46

d. All of the above

Question 47

11. Which is the least abundant granulocyte in peripheral blood? a. Basophils. b. Mast Cells. c. Neutrophil. d. Eosinophils.

Answer 47

a. Basophils.

Question 48

13. What is the vesicle into which a bacteria is initially engulfed by a macrophage a. lysosome b. endosome c. phagosome d. Phagolysosome

Answer 48

c. phagosome

Question 49

1. Which of the options below best completes the following statement: NK cells are of ___________ origin and target __________ for their elimination. a. lymphoid, altered host cells b. myeloid, pathogenic antigens c. lymphoid, bacterial membrane components d. myeloid, altered host cells

Answer 49

a. lymphoid, altered host cells

Question 50

2. Which of the options below best completes the following statement: Perforin is a protein secreted by NK cells which.......... a. mediates the polymerisation of C9 to form pores on the surface of bacteria. b. permits the entry of granzymes to NK cells. c. polymerise into channel-forming aggregates in the plasma membrane of target cells inducing osmotic lysis. d. detects the surface expression of MHCI on the surface of host cells.

Answer 50

c. polymerise into channel-forming aggregates in the plasma membrane of target cells inducing osmotic lysis.

Question 51

3. Which of the options below best completes the following statement: NK cell cytotoxicity is mediated by.............. a. activating signals. b. lack of inhibitory signals. c. expression of ligands that stimulate ‘death’ receptors on target cells. d. All of the above.

Answer 51

d. All of the above.

Question 52

4. Which molecule below is a fungal pathogen-associated molecular pattern (PAMP)? a. Double stranded RNA. b. Lipopolysaccharides. c. Zymosan. d. Unmethylated CpG motifs.

Answer 52

c. Zymosan.

Question 53

5. From the options below, which pattern recognition receptor (PRR) gene family is expressed by innate immune cells? a. NOD like receptors. b. RIG-I-like receptors. c. Toll like receptors. d. All of the above.

Answer 53

d. All of the above.

Question 54

6. Which of the options below completes the following statement: Intracellular expression by innate immune cells is characteristic of............ a. TLR3, TLR7 and TLR4. b. TLR9, TLR4 and TLR5. c. TLR6, TLR2 and TLR1. d. TLR3, TLR7 and TLR9.

Answer 54

d. TLR3, TLR7 and TLR9.

Question 55

7. The definition, ‘Innate and adaptive immune cell secreted protein that act as signalling molecules in an immune response’ corresponds to? a. Surfactants b. Cytokines c. Antimicrobial Peptides d. Lysozymes

Answer 55

Cytokines

Question 56

8. Leukocyte secreted cytokines, which act on leukocytes, are known as........ a. Lymphokines b. Monokines c. Chemokines d. Interleukin

Answer 56

d. Interleukin

Question 57

9. A cytokine that induces multiple effects on different immune cells is said to be...... a. Pleiotropic b. Autocrine c. Synergistic d. Antagonistic

Answer 57

a. Pleiotropic

Question 58

10. An example of a cytokine produced by activated macrophages with a major role on the innate immune response is: a. IL-2 b. TNF c. IL-4 d. IL-17

Answer 58

b. TNF

Question 59

The primal developmental organ of T cells corresponds to the: A. Thymus B. Thyroid C. Bone Marrow D. Both options A and B are correct.

Answer 59

A. Thymus

Question 60

During negative selection, a strong interaction between an immature T cell receptor and selfpeptide: A. Is favourable, as it ensures that antigens presented in the context of MHC are recognized by T cells B. Rescues the T cell from programmed cell death C. Results in the T cell migrating to the periphery D. None of the above

Answer 60

None of the above

Question 61

Central tolerance: A. Only occurs in the thymus B. Promotes Autoimmunity C. Rescues T cells that recognize self-antigens D. Also involves peripheral tolerance

Answer 61

D. Also involves peripheral tolerance

Question 62

T cells that have Αβ T cell receptors: A. Do not express CD4 + or CD8 + B. Constitute 95% of T cells C. Do not need MHC to interact with antigens D. Are not involved in adaptive immunity

Answer 62

B. Constitute 95% of T cells

Question 63

T cells that express γδ chains: A. Have ‘Innate like’ immune features B. Express either CD4 + or CD8 B. Express + either CD4 + or CD8+ C. Undergo extensive gene rearrangements D. Can have a wide variety of antigen specificities

Answer 63

Have ‘Innate like’ immune features

Question 64

The CD3 component of the TCR complex is involved in: A. Recognizing antigenic peptides associated to MHC complexes B. Signal transduction via phosphorylation of ITAMs C. Direct interaction with MHCII and MHCI D. Permits the initial interaction between a T cell and the antigen presenting cell

Answer 64

B. Signal transduction via phosphorylation of ITAMs

Question 65

CD4 + T cells: A. Recognise antigenic peptides presented in the context of MHCII B. Recognise antigenic peptides produced by proteasome processing C. Recognise MHCI on most nucleated cells D. Are also known as cytotoxic T cells

Answer 65

A. Recognise antigenic peptides presented in the context of MHCII

Question 66

• CD8 co-receptors: A. Are expressed on approximately 65% of T cells B. Interact with MHCII C. Are expressed in approximately 35% of T cells D. Is a marker of T helper cells

Answer 66

. Are expressed in approximately 35% of T cells

Question 67

A characteristic of pathogen produced superantigens is that they: A. Cause specific activation of T cells B. Prevent T cell activation by binding directly to the antigen binding site of MHC complexes C. Block the secretion of cytokines D. Induce excessive uncontrolled immunity as a defence mechanism to avoid antigen specific immune responses

Answer 67

D. Induce excessive uncontrolled immunity as a defence mechanism to avoid antigen specific immune responses

Question 68

1. Which of the statements below describe a similarity between T and B cell receptors? a. They both have more than one binding site. b. Interaction of the receptor variable region with a specific antigen is fundamental for lymphocyte activation. c. Their structure include α and β chains. d. They can be secreted as antibodies.

Answer 68

b. Interaction of the receptor variable region with a specific antigen is fundamental for lymphocyte activation.

Question 69

Which of the following immune cells is capable of secreting large amounts of antibody? a. T lymphocytes. b. Thymocytes. c. Plasma cells. d. None of the above

Answer 69

c. Plasma cells.

Question 70

Which of the statements below correctly describes B cells and plasma cells? a. Both are lymphocytes showing a high level of B cell receptor expression on their surface. b. Both show little cytoplasm and a round nucleus. c. Both show a large cytoplasm containing rough ER. d. Plasma cells are differentiated B cells with the primary role of secreting antibodies.

Answer 70

d. Plasma cells are differentiated B cells with the primary role of secreting antibodies.

Question 71

## Footnote Complete the following sentence. The antigen binding site of an antibody is located..... a. between the variable region of the heavy and light chains. b. between the constant region of the heavy and light chains. c. between the variable regions of the heavy chains only. d. between the constant regions of the light chains only

Answer 71

a. between the variable region of the heavy and light chains.

Question 72

What is the major structural difference between B cell antigen receptor (BCRs) and secreted antibody? a. Heavy chains are absent in the BCR. b. Secreted antibodies lack a cytoplasmic tail. c. BCRs have a single antigen binding site. d. All of the above are correct

Answer 72

b. Secreted antibodies lack a cytoplasmic tail.

Question 73

What is the difference between the recombination of heavy and light chain variable regions? a. Recombination of the light chain only relies on Recombination Activating Gene (RAG) 1 and 2. b. The resulting heavy chain is comprised of a variable, a diversity and a joining segment whereas the light chain lacks a diversity segment. c. The resulting light chain is comprised of a variable, a diversity and a joining segment whereas the heavy chain lacks a diversity segment. d. Both options ‘a’ and ‘b’ are correct

Answer 73

b. The resulting heavy chain is comprised of a variable, a diversity and a joining segment whereas the light chain lacks a diversity segment

Question 74

Which of the components listed below forms the B cell antigen receptor? a. IgG antibody. b. Igα. c. Igβ. d. All of the above.

Answer 74

d. All of the above.

Question 75

Complete the following sentence. Initiation of the germinal centre reaction is mediated by the......... a. activation of T cells by cytokines. b. activation of B cells by CD40 ligation. c. interaction between B cells and dendritic cells. d. all of the above.

Answer 75

. activation of B cells by CD40 ligation.

Question 76

Complete the following sentence. Revision Questions Proliferation and differentiation of B cells can be enhanced by thymus independent antigens including...... a. interaction of PAMPs with corresponding TLRs activating downstream signalling which in turn stimulate B cell proliferation and differentiation. b. a. recognition of opsonised pathogens by binding of the complement component C3d to the B cell co-receptor CD21 which enhance BCR signalling. c. recognition of opsonised pathogens by binding of the complement component C5d to the B cell co-receptor CD21 which enhance BCR signalling. d. both ‘a’ and ‘b’.

Answer 76

d. both ‘a’ and ‘b’.

Question 77

Somatic hypermutation consists of the........ a. recombination of gene segments to generate the gene encoding the heavy or light chain variable regions of the BCR. b. introduction of point mutations into the rearranged VL & VH genes in order to increase antigen affinity. c. selection process by which stromal cells present self- antigen to B cells in the bone marrow to control autoreactive B cells. d. recognition of specific antigen by a BCR which induces B cell activation and clonal expansion.

Answer 77

b. introduction of point mutations into the rearranged VL & VH genes in order to increase antigen affinity.

Question 78

Which of the following statements does not describe an antibody (Ab) effector function? a. Mediate cytotoxicity by the process known as antibody -dependent cellular cytotoxicity (ADCC). b. Antibodies polymerise on the surface of target cells forming pores which induces their lysis. c. Antibodies mediate the neutralisation and opsonisation of microbes. d. Activate complement

Answer 78

Antibodies polymerise on the surface of target cells forming pores which induces their lysis.

Question 79

Complete the following sentence. The most common antibody isotype found in serum, with roles in opsonisation, complement activation and ADCC as well as neonatal immunity is..... a. IgA b. IgE c. IgG d. IgM

Answer 79

c. IgG

Question 80

Complete the following sentence. During an immune response, the first antibody isotype expressed is.......... a. IgA b. IgE c. IgG d. IgM

Answer 80

d. IgM

Question 81

How does the concept of affinity differ from avidity? a. Affinity refers to the strength of interaction of one binding site whereas avidity is the combined strength of multiple binding sites. b. Avidity refers to the strength of interaction of one binding site. c. Affinity is the combined strength of multiple binding sites. d. Both b and c are correct.

Answer 81

a. Affinity refers to the strength of interaction of one binding site whereas avidity is the combined strength of multiple binding sites.

Question 82

Complete the following sentence. The antibody isotype which displays the highest avidity due to its pentameric form, and is capable of complement recruitment corresponds to..... a. IgA b. IgE c. IgG d. IgM

Answer 82

. IgM

Question 83

The predominant antibody isotype in external secretions that can neutralise pathogens and toxins and prevent their interaction with mucosal surfaces is a. IgA b. IgE c. IgG d. IgM

Answer 83

a. IgA

Question 84

The antibody isotype that provides immunity against helminths and is capable of sensitising mast cells resulting in the induction of an allergic response is a. IgA b. IgE c. IgG d. IgM

Answer 84

. IgE

Question 85

Which of the following statements is characteristic of isotype switching? a. A process required for expression of IgM but not for expression of for expression of IgG, IgA or IgE. b. Is a reversible change in DNA that permits the transmembrane expression and secretion of IgG, IgA or IgE. c. Occurs in the germinal centre and depends on cytokine signalling and CD40 ligation. d. All of the above are correct.

Answer 85

c. Occurs in the germinal centre and depends on cytokine signalling and CD40 ligation.

Question 86

In addition to CD40 ligation, which of the statements below identify a cytokine that induce a correct antibody isotype? a. IFN γ induces an induces an IgA switch. switch. b. IL-4 or IL-13 induces an IgE switch. c. TGF β induces an IgG switch. d. All of the above are correct

Answer 86

b. IL-4 or IL-13 induces an IgE switch.

Question 87

Complete the following sentence. A feature which does not describe patients presenting with x-linked hyper IgM syndrome is.......... a. T cells that do not express CD40L. b. B cells that cannot undergo isotype switching. c. They present normal levels of all antibody isotypes, however only IgM is functional. d. Are highly susceptible to infections with pyogenic bacteria

Answer 87

c. They present normal levels of all antibody isotypes, however only IgM is functional