PRACTICE MCQ Cell mediated Immunity

Question 1

In an experiment, a cell culture containing CD4 and CD8 lymphocytes is stimulated to undergo proliferation. It is observed that proliferation of naïve CD4 and CD8 cell clones can be mediated through an autocrine response. Which of the following cytokines released from these lymphocytes is most likely to produce this autocrine effect?

a. Interferon-gamma
b. TGF B
c. IL-2
d. IL-5

Answer 1

IL-2

Question 2

In a study of T lymphocyte activation, co-stimulation of CD4 cells is observed to occur when antigen presenting cells (APCs) are present. The APCs are expressing B71/B72 on their cell surfaces. Which of the following receptors on these CD4 cells is most likely to interact with the B71/B72 on the APCs?

a. CD28
b. CD20
c. CD44
d. CD25
c. CD3

Answer 2

CD28

Question 3

In an experiment, the result of T cell interaction with peptides complexed with MHC molecules is studied. When B cells are added, it is observed that immunoglobulin synthesis in the B cell increases. Which of the following cell surface markers is most likely to be present on these T cells?

a. CD8
b. CD4
c. CD28
d. CD20
e. CD10

Answer 3

CD4 cells are the ‘helper’ T cells that aid in antibody production

Question 4

In a study of macrophage function, it is shown that macrophages that encounter MHC molecules undergo stimulation and upregulate cell surface expression of substances that facilitate adhesion of T cells to the macrophages. Which of the following is most likely to be increased on the surfaces of these macrophages to promote T cell adhesion?

a. immunoglobulins
b. interleukins
c. selectins
d. integrins
e. interferons

Answer 4

integrin expression can be upregulated in this case by CXCR3 integrins act to produce cell binding.

Question 5

Antigen presenting cells, including dendritic cells in lymph nodes, are observed to bind T cells on their surfaces. This binding is increased when the dendritic cells have increased activation of cell surface receptors. Which of the following receptors is most likely to have this function?

a. chemokines
b. CD3
c. CD28
d. Fc
e. T- cell

Answer 5

Chemokine receptors increase the likelihood of binding. Variations in the chemokine receptors may explain variations in the nature and degree of an immune response.

Question 6

In an experiment, CD40 ligand (CD154) interaction with CD40 on cell surfaces is observed to improve cytokine secretion. The amount of B7 or interleukin-12 (IL-12) secreted is shown to be increased. Which of the following cells is most likely to interact with CD40 ligand in this manner?

a. dendritic cell
b. neutrophil
c. B cell
d. T-cell
e. NK cell

Answer 6

APCs such as dendritic cells or macrophages, can be stimulated by CD40 to increase the magnitude of an immune response via cytokine release of IL-12

Question 7

In an allergic reaction to inhaled pollen, it is shown that mast cells near vascular channels in the nasal mucosa have bound IgE molecules which interact with pollen antigen. The mast cells release cytokines in response to this binding. Which of the following interleukins is most likely to be released by these mast cells?

a. IL-3
b. IL-7
c. IL-12
d. IL-4
e. IL-6

Answer 7

IL-4 …. and IL-5 contribute to allergic reactions. This is also part of the TH2 response.

Question 8

A 78-year-old man has had malaise along with a low-grade fever and non-productive cough for the past week. His temperature is 37.8 C. A chest radiograph reveals minimal interstitial infiltrates but no effusions or areas of consolidation. A week later, his symptoms are subsiding. Which of the following cells directed against which organism is most likely to have increased in number in his hilar lymph nodes?

a. Langhans giant cells engulfing Mycobacterium tuberculosis
b. CD8 cells directed against influenza B virus
c. Neutrophils phagocytizing opsonized Streptococcus pneumoniae
d. Plasma cells secreting IgG against Staphylococcus aureus
e. NK cells attracted to Fc receptors displayed on dendritic cells with HIV

Answer 8

The findings fit with a viral pneumonia. There is tremendous clonal expansion of CD8 cells specific for viral (intracellular) antigens

Question 9

In a study of T cell stimulation, it is observed that CD4 ‘helper’ cells can help B cells, macrophages, and dendritic cells increase their function in an immune response. These CD4 cells produce a costimulator. Which of the following is most likely to serve as a costimulator released from CD4 cells?

a. B7
b. C3b
c. CD40 L
d. IL-12
c. TNF

Answer 9

CD40 ligand on T helper cells binds to CD40 receptor to stimulate antigen presenting cells and B cells.

Question 10

A 52-year-old woman has had malaise with fever and non-productive cough for 4 weeks. Her temperature is 37.7 C. A chest radiograph shows upper lobe cavitation along with infiltrates and focal calcifications. In this situation, there is more likely to be a subset of T helper cells secreting which of the following substances?

a. CD40 Ligand
b. GM-CSF
c. IL-4
d. IFN y
e. TGF- beta

Answer 10

TH1 response. In this case, the patient is likely to have tuberculosis, and stimulation of macrophages by interferon-gamma to increase activity and become giant cells is very useful

A. is not a secreted substance
B. is not relevant
E. is inhibition of infalmmatory response

Question 11

A 33-year-old man has received a renal transplant from a living related donor. He is given the drug cyclosporine to prevent rejection of the allograft. As a consequence, he has less production of interleukin-2. The activity of which of the following substances has been reduced by the cyclosporine to account for the immunosuppression?

a. AP-1
b. Calcineurin
c. CXCR3
d. histamine
e. Interleukin 5

Answer 11

The calcineurin is activated by calmodulin. Calcineurin is an enzyme that dephosphorylates NFAT to activate genes transcribing for IL-2 and its receptor

TARGET FOR immunosuppressant drugs

Question 12

A 7-year-old child lives in a community without a sewage system, and waste water collects in the streets from toilets and latrines. The child playing in the street becomes infected with the filariform larvae of Strongyloides stercoralis. CD4 cells which encounter the organisms secrete interleukin-4 (IL-4). Which of the following classes of immunoglobulin is most likely to be produced in response to this stimulus?

a. IgA
b. IgG
c. IgM
d. IgE
e. IgD

Answer 12

IgE: Parasitic infections, particularly roundworms, elicit a TH2 cell mediated immune response, with IgE antibody production and eosinophilic infiltrates in tissues.

Question 13

At the site of a subcutaneous infection with Streptococcus pyogenes, blood monocytes transform into macrophages and begin secreting TNF and IL-1. These cytokines then stimulate endothelial cells. The endothelial cells begin to express a substances that promotes the migration and binding of activated lymphocytes. Which of the following is most likely to be expressed by these endothelial cells?

a. P selectin
b. LDL receptor
c. TCR
d. IL-8
E. Thrombomodulin

Answer 13

Selectins aid in TRANSIENT binding of leukocytes for a variety of purposes

Question 14

n an experiment, naïve CD4 cells are added to a culture of macrophages. It is shown that the production of nitric oxide synthase is upregulated within macrophages when they are stimulated by interferon-gamma. Which of the following cytokines released by macrophages is most likely to stimulate the naïve CD4 cells to produce the interferon gamma?

a. IL-1
b. IL-2
c. IL- 4
d. IL-12
e. IL-6

Answer 14

Both CD4 cells and NK cells respond to IL-12 by cytokine secretion, particularly IFN-gamma

Question 15

A 31-year-old man becomes infected with Mycobacterium leprae. Over the next 10 years he develops disfiguring skin lesions. A skin biopsy shows numerous acid fast bacilli within macrophages in the dermis. Which of the following mechanisms is the most likely cause for these findings?

a. diminished # of NK cells
b. INcrease b cells differentiating in plasma
c. predominance of Th2 subset of CD4 cells
d. stimulation of monocyte produciton in bone marrow

Answer 15

TH1 response&raquo_space; Th2 for bacterial infections

Th2 involved in tissue repair

Question 16

In an experiment, cytotoxic lymphocytes are introduced into culture of virally infected cells. It is shown that these lymphocytes recognize and target the infected cells that display peptides on their cell surfaces. To which of the following molecules are these peptides most likely bound to achieve this effect?

a. CD3
b. C3b
c. IgG
d. Il-2
e. MHC 1

Answer 16

E

Question 17

A 58-year-old woman has had a fever and cough for the past month. She has a chest radiograph showing multiple small nodules, particularly in upper lobes. Laboratory studies show acid fast bacilli in her sputum. Which of the following cells is most important in producing this radiographic appearance?

a. CD4 cell
b. plasma cell
c. eusinophil
d. neutrophil
e. NK cell

Answer 17

A

Question 18

In a study of viral infections, it is shown that some viruses have evolved mechanisms to evade destruction mediated through cytotoxic CD8 cells. These viruses are most likely found to encode for proteins that can inhibit which of the following intracytoplasmic events?

a. Activation of caspases
b. elaboration of NO
c. mRNA translation
d. production of MHC 1 molecules
e. immunoglobulin synthesis

Answer 18

need MHC 1 to target viral pathogens

Question 19

In an experiment conducted with Listeria monocytogenes, it is observed that the microbes become intracellular within a phagocyte. Within the phagocyte, the microbes avoid destruction, even though interferon-gamma is present in a paracrine feedback loop with nearby CD4 cells. By which of the following mechanisms have these microbes most likely avoided destruction?

a. Incorporation within the host cell genome
b. Inhibition of phagolysosome formation
c. Production of soluble cytokine receptor
d. Synthesis of cell wall mycolic acid

Answer 19

B. inhibition of phagolysosome formation

Question 20

A study is conducted with a culture of B cells infected by Epstein-Barr virus (EBV). It is observed that when macrophages are added to the culture, no macrophage activation occurs. The B cells are found to be secreting a factor which inhibits macrophage activation. Non-EBV infected B cells do not secrete this factor. Which of the following interleukin molecules is this inhibitor most likely to be?

a. IL-2
b. IL-10
c. IL-5
d. IL-7
e. IL-12

Answer 20

IL-10 , EBV inhibits an immune response to evade destruction.

Question 21

Before T cells become activated, they require antigen encounter. Naïve T cells are shown to express L-selectin which aids in binding to high endothelial cells expressing L-selectin ligand in regions where they are most likely to encounter antigen. In which of the following locations are these high endothelial cells most likely to be lcoated?

a. bone marrow
b. capillaries
c. spleen
d. lymph nodes
e. spleen
f. thymus

Answer 21

LYMPH nodes, The lymph nodes are the site for antigen contact, since many antigens can circulate via the bloodstream to reach nodes where specific lymphocyte clones are found to react to the antigen.

Question 22

In a study of TH1 immune responses, it is observed that CD4 cells can recognize microbial peptides displayed with MHC II molecules on the surfaces of macrophages. When this recognition occurs, the CD4 cells begin expressing a substance on their cell surfaces which interacts with a macrophage receptor. This interaction leads to secretion of interferon-gamma by the CD4 cells. Which of the following substances is most likely displayed on these CD4 cells to interact with the macrophages?

a. TGF
b. MHC 1
c. IL-2
d. CD40 L
e. Integrin

Answer 22

CD40 ligand interacts with CD40 on the macrophage surface. This interaction brings the CD4 cell in close proximity to macrophages that require interferon-gamma activation to kill ingested microbes.

Question 23

Following a skin abrasion and local minor infection, scar tissue is normally formed. This is due to proliferation of fibroblasts and deposition of extracellular material and is stimulated by which of the following?

a. IL-1
b. IL-17
c. TGF-B
d. G-CSF

Answer 23

C.

TGF-β is a potent stimulator of fibroblasts and the development of fibrosis. IL-1 and IL-17 may have had a part in the immune response at the site but are not involved in scar formation.

Question 24

Patients suffering from toxic shock syndrome are found to have which of the following as the causative mechanism?

a. high level of bacterial toxin
b. high level of bacterial specific antibody
c. ag- ab complex formation
d. massive stimulation of Th cells irrespective of antigenic specificity

Answer 24

D. Superantigen

The toxin of the bacteria reacts with a commonly used sequence in the V region of the β chain of the T cell receptor.

Question 25

Patients with Hodgkin’s lymphoma frequently have eosinophils associated with the malignant cells in the lymph nodes and eosinophilia (high eosinophil levels) in their blood. This is due to the increased production of which cytokine by the malignant cells?

a. IL-1
b. IL-10
c. TNF alpha
d. IL-5

Answer 25

D.

IL-5 is a growth and differentiation factor for eosinophils

Question 26

A Patient encounters the helminth Onchcerca volvulus after swimming in a parasite-infested river in West Africa. Following interaction with the patient’s innate immune system, one would expect and hope for the development of which subtype of T cells in response to the organism?

a. Th1
b. Th17
c. Th2
d. TREG
e. NKT

Answer 26

C.

CD4+Th2 subset is the subpopulation that helps the B cell in class (isotype) switching to IgE, the antibody type most effective against parasites

Question 27

A 2-year-old child with a sore throat is tested for antistreptococcal antibody to see if the infection is due to this bacterium. The child is found to have only IgG antibodies to this organism with no detectable IgM. This indicates which of the following?

a. remote, not a current, infection with streptococcus
b. passive transfer of maternal IgG across the placenta
c. an immunodeficiency disease in which only IgM is lacking
d. overwhelming infection with streptococcuss

Answer 27

A.

The presence of IgG indicates that the child was exposed and responded to streptococcus. This could be entirely in the past. The presence of IgM would be evidence for a current infection