Flaherty: Immunology for Pharmacy

Chapter 01: Cells and Organs of the Immune System

Test Bank

MULTIPLE CHOICE

1.	The main function of _______________ is to ingest and destroy bacteria.
a.	B cells	
b.	Eosinophils	
c.	Natural killer (NK) cells	
d.	Polymorphonuclear leukocytes (PMNs)	

ANS:	D
B cells and NK cells have a variety of immune functions, but neither can ingest organisms. While eosinophils can ingest organisms, their main function is to degranulate to kill large parasites.

2.	Monocytes are primarily located in the:
a.	Liver	
b.	Blood	
c.	Spleen	
d.	Lymph nodes	

ANS:	B
When monocytes migrate to tissues, such as the liver, they become macrophages. Specifically, macrophages in the liver are known as Kupffer cells. Monocytes can circulate through the spleen and lymph nodes, but the main cells in those organs are lymphocytes and macrophages. Monocytes primarily circulate in the blood.

3.	Monocytes enter tissue and develop into:
a.	PMNs	
b.	Mast cells	
c.	Plasma cells	
d.	Macrophages	

ANS:	D
Mast cells are located in the tissues, but they are a distinct cell type and do not develop from another circulating cell. Activated B cells develop into plasma cells. PMNs are found in the blood, and are a distinct cell type that does not develop from another circulating cell. Monocytes enter tissues and develop into the larger macrophages that either remain fixed in the tissue or move through the tissues searching for debris and pathogens.

4.	All T cells express which of the following CD markers?
a.	CD3	
b.	CD4	
c.	CD8	
d.	CD16	

ANS:	A
The CD3 marker is expressed on all T cells as part of the T cell receptor (TCR). The CD4 marker is specific for T helper cells, and the CD8 marker is specific for cytotoxic T cells. The CD16 marker, along with CD56, is found on NK cells.

5.	Which of the following cells is important for killing virus-infected cells?
a.	NK cells	
b.	Basophils	
c.	Monocytes	
d.	Plasma cells	

ANS:	A
The main function of NK cells is to kill cells that are infected with intracellular pathogens, mainly viruses, and to kill tumor cells. Basophils are mainly involved in allergic reactions and in the destruction of large gastrointestinal parasites. Monocytes usually ingest only small pathogens, such as bacteria. Plasma cells produce antibodies, and do not have the capability to kill other cells.

6.	Immature thymocytes begin their initial cycle of proliferation in:
a.	The thymic cortex	
b.	Hassall’s corpuscles	
c.	The germinal center	
d.	The lymph node medulla	

ANS:	A
T cells begin maturation in the thymic cortex and migrate to the medulla to undergo further maturation and differentiation. Hassall’s corpuscles contain degenerating cells in the thymus. B cells proliferate in the germinal centers in the cortex of the lymph node, and the medulla of the lymph node contains a variety of cells involved in facilitating antigen-antibody interactions.

7.	In positive selection, thymocytes undergo apoptosis when:
I. They do not interact with MHC molecules
II. They bind to MHC molecules with high affinity
III. They bind to MHC molecules with low affinity
a.	I only	
b.	III only	
c.	I and II	
d.	II and III	
e.	I, II, and III	

ANS:	C
In positive selection, thymocytes that do not interact with MHC undergo apoptosis because they are nonreactive. Thymocytes that bind to MHC with high affinity also undergo apoptosis because they are considered autoreactive. Thymocytes that bind to MHC with low affinity are considered non-threatening and migrate deeper into the thymic cortex for further maturation.

8.	The role of microfold (M) cells is to:
a.	Trap antigens	
b.	Kill pathogens	
c.	Present antigens	
d.	Produce antibodies	

ANS:	A
M cells in the Peyer’s patches of the intestine have invaginated surfaces that serve to trap antigens. The antigens can then be transported across the submucosa so that intraepithelial lymphocytes can interact with the antigen.

9.	The main purpose of diapedesis is to:
a.	Aid neutrophils in granule release	
b.	Capture antigens for presentation to lymphocytes	
c.	Allow immune cells to travel to the site of infection	
d.	Activate macrophages for more effective phagocytosis	

ANS:	C
Diapedesis is the process by which immune cells leave the circulation and travel to the site of an infection. This process is initiated by the release of chemokines by cells already at the site. In response to the chemokines, endothelial cells upregulate adhesion molecules that grab passing white blood cells, particularly neutrophils (PMNs), and slow them down. The neutrophil then squeezes between endothelial cells and moves through the tissues to the site of infection, guided by the chemokines. The process of diapedesis does not involve antigen capture, granule release, or phagocytosis, but is often a step that follows or precedes these events.

10.	Which cell type contains granules that are specific for killing parasites?
a.	PMNs	
b.	Eosinophils	
c.	Macrophages	
d.	Large granular lymphocytes	

ANS:	B
Eosinophils have large granules that contain substances, such as major basic protein (MBP) and eosinophilic cationic protein (ECP), that specifically target large parasites. Macrophages do not have granules. Large granular lymphocytes (LGLs) and PMNs have granules, but those granule components are used for purposes other than killing large parasites. LGLs mainly kill virus-infected cells and tumor cells, and the granules in PMNs aid in killing small pathogens, such as bacteria, that are ingested by phagocytosis.

11.	What role does the T helper 1 (Th1) subset play in the immune response?
a.	Inhibits viral replication	
b.	Causes target cell death of infected cells	
c.	Assists B cells in the production of antibody	
d.	Generates inflammatory responses to pathogens	

ANS:	D
T helper 1 cells generate inflammatory responses, while T helper 2 (Th2) cells assist with antibody production. Cytotoxic T cells subset 1 (Tc1) are important to kill infected target cells, and cytotoxic T cells subset 2 (Tc2) are able to inhibit replication of viruses and tumor cells.

12.	The __________________ serves as a filter to trap infections in the tissues.
a.	Spleen	
b.	Thymus	
c.	Bone marrow	
d.	Lymph system	

ANS:	D
Tissue fluid drains into the lymphatic system and then circulates through the lymph nodes. Cells that have captured antigen for presentation remain in the lymph nodes to interact with B and T cells. The spleen serves a similar function, but for pathogens that are circulating in the blood. The bone marrow and thymus are involved in B and T cell maturation, but are not involved in facilitating interactions between antigen and lymphocytes.

13.	B cells that are actively proliferating are located in the ________________ of the lymph node.
a.	Mantle layer	
b.	Germinal center	
c.	Medullary region	
d.	Paracortical region	

ANS:	B
While some of the other areas may contain B cells, the germinal center is part of the lymph node cortex and contains B cells that have been activated and are proliferating. The mantle layer surrounds the germinal centers and contains memory B cells. The paracortex is located between the follicles and contains a variety of cells types, including macrophages and T helper cells. The medullary region is the center area of the lymph node and also contains different cell types, as well as medullary sinuses.

14.	Aged red blood cells are destroyed by macrophages in the:
a.	Tonsils	
b.	Lymph nodes	
c.	Peyer’s patches	
d.	Splenic red pulp	

ANS:	D
The splenic red pulp is the area where aged red blood cells are destroyed by macrophages, while the white pulp is the area where T and B cells interact with cells presenting antigen from blood-borne pathogens. The tonsils and Peyer’s patches are both areas of mucosal-associated lymphoid tissue (MALT), which are areas that interact with pathogens that have breached the mucosal barriers, but have no role in red blood cell destruction. Lymph nodes serve a similar function to the spleen, acting as a filter for pathogens in the tissue. However, the lymph nodes do not have an area of red cell destruction as the spleen does.

15.	Which of the following congenital disorders results in defects in the thymus?
I. Nezelof Syndrome
II. DiGeorge Syndrome
III. Leukocyte Adhesion Deficiency
a.	I only	
b.	III only	
c.	I and II	
d.	II and III	
e.	I, II, and III	

ANS:	C
Both Nezelof syndrome and DiGeorge syndrome are inherited disorders that result in a range of defects, but both result in abnormalities of the thymus that lead to T cell dysfunction. One distinction between the two disorders is that patients with Nezelof syndrome have normal parathyroid function, while those with DiGeorge syndrome have a defective parathyroid. Leukocyte adhesion deficiencies are inherited disorders that lead to impaired migration by immune cells to the site of infection due to lack of expression of adhesion molecules, and these disorders do not affect thymic function.

16.	Development of which cell type is impaired in DiGeorge syndrome?
I. T cells
II. B cells
III. NK cells
a.	I only	
b.	III only	
c.	I and II	
d.	II and III	
e.	I, II, and III	

ANS:	A
DiGeorge syndrome affects thymic function. Therefore, T cell development is impaired. In Nezelof syndrome, patients may lack functional adenosine deaminase (ADA) enzymes, which leads to impaired development of all three cell types, but ADA enzymes are functional in DiGeorge syndrome.

17.	As a result of leukocyte adhesion deficiency, white blood cells cannot:
a.	Present antigen	
b.	Release granules	
c.	Perform diapedesis	
d.	Phagocytose pathogens	

ANS:	C
Adhesion molecules are important for adherence of leukocytes to the surface of endothelial cells during diapedesis. This process allows the cells to leave the circulation and travel to the site of infection. Patients with leukocyte adhesion deficiency do not express these surface molecules on their immune cells, so their white blood cells cannot migrate to the site of infection to aid in elimination of pathogens. The adhesion molecules that are defective in leukocyte adhesion deficiency are not involved in antigen presentation, granule release, or phagocytosis.

18.	Hematopoiesis is the:
a.	Development of blood cells	
b.	Development of cancer cells	
c.	Development of immune cells	
d.	Development of immune response	

ANS:	A
Hematopoiesis is the production of all blood cells, not just the immune cells. Hematopoiesis has nothing to do with the production of cancer cells or with the development of the immune response.

19.	The granules in polymorphonuclear leukocytes (PMNs) play which of the following roles in the immune response?
a.	Assist in antibody production	
b.	Kill cells infected with viruses	
c.	Destroy phagocytosed bacteria	
d.	Aid cells in ingestion of bacteria	

ANS:	C
The granules of PMNs contain substances, including lysozyme and myeloperoxidase, that are involved in killing and destroying pathogens that have been taken up by phagocytosis. This process occurs following ingestion of the pathogen. PMNs do not produce antibodies or kill virus-infected cells.

20.	Phagocytosis is the main function of which of the following cell types?
a.	NK cells	
b.	Basophils	
c.	Eosinophils	
d.	Macrophages	

ANS:	D
Macrophages ingest pathogens by phagocytosis. Eosinophils can phagocytose small parasites, but it is not their main function. Their main function is to degranulate on large parasites to cause damage and death of the parasite. Basophils and NK cells are not able to phagocytose pathogens at all.