Question 1

A phagocytic cell lacking the enzyme myeloperoxidase would be deficient in the production of:

 Question 2

Macrophages are considered to be key cells in wound healing. Which of the following best explains their role?

C.  Macrophages remove debris and secrete cytokines such as TGFb, which promote fibroblast chemotaxis.

 Question 3

In many pathologic processes, the final effects induced by free radicals depend on the net balance between free radical formation and termination. Of the following, which acts to favor the formation of reactive species?

Answer C, xanthine oxidase.

The enzyme xanthine oxidase is a particularly well known source of superoxide during the reperfusion phase of ischmia-reprefusion.

 Question 4

CD8 cytotoxic T cells are:

B. Cells that have a T cell receptor for antigen that is MHC class I restricted.

CD8 cytotoxic T cells are cells that express CD8 molecule and recognize antigens that are MHC class I restricted.

Single positive CD8+ T cells reside primarily in lymphoid organs and circulation.

However most of the cells in the thymus are immature, double positive T cells that express both CD4 and CD8 molecules.

The majority of CD8+ T cell activation is dependent on CD4+ T cell help except in rare conditions such as transplantation.

 Question 5

The T cell receptor for antigen can be defined as:

A. A gene which is assembled by somatic recombination from sets of genes in the same way as are the immunoglobulin genes.

T cell receptor is highly diverse receptor that recognizes polymorphic MHC molecules and specific antigens/peptides. They consist of ƒÑ and ƒÒ chains that have structural similarities with Ig polypeptides. Both ƒÑ and ƒÒ chains has variable and constant region similar to immunoglobulin (Ig).

The presence of genes such as V, D, J, and C is characteristic of both T cell receptor and Ig. However, in contrast to Ig which recognize conformational or linear epitopes on the antigen directly, TCR recognize antigens in the form of peptides bound to MHC molecules.

 Question 6

T cells that produce a Th2 cytokine profile are usually referred to as:

B. CD4+ T cells that produce IL4

T cells that produce Th2 cytokine profile are usually referred to as CD T cells that produce IL-4.

CD4+ T cells that produce IFN-ƒ× are called Th1 cells. CD4+ T cells that produce both IFN-ƒ× and IL-4 are called Th0.

Although CD8+ T cells can differentiated into two phenotypes similar to CD4 T cells that produce either IL-4 or IFN-ƒ×, the term ¡§Th¡¨ always refer to T helper cells, which are only CD4+ T cells.

 Question 7

In post streptococcal glomerulonephritis,...

C. Antibodies generated against streptococcal antigens form immune complexes that are deposited in the glomeruli.

This is right from your lab case. Jack Johnson has post streptoccal glomerulonephritis. He no longer has a streptococcus infection. This condition usually occurs 1-4 weeks after the infection and is due to deposition of immune complexes in the glomeruli of the kidney.

 Question 8

Eosinophilia and the control of parasitic infection can be associated with the production of:

C. IL-5

Eosinophilia and control of parasitic infection can be associated with production of IL-5.

Macrophage-colony stimulating factor is responsible for recruitment of inflammatory cells.

IFN-Ą is responsible for activation of anti-viral killing mechanisms.

IL-3 is T cell growth factor.

IL-4 is Th2 cytokine that promote B cell differentiation to IgG 1, IgG3, and IgG4 (Th2 isotypes).

• Question 9

For each biological activity or feature select the most likely type of cell (Each lettered option may be used once, more than once, or not at all).

#12 - (B) - B cells is a professional antigen presenting cells that are able to recognize the antigen in an antigen specific manner via immunoglobulin receptor, process the antigens into peptides and present these specific peptides to antigen specific CD4+ T cells in the context of MHC class II>

#13 - (A) - Neutrophil is highly motile, phagocytic cells which constitute the first line of innate defense against several extracellular, intracellular bacteria and fungi.

#14 - (A) - Neutrophil intracellular killing mechanisms is dependent of cytochrome B

Question 10

After restoration of perfusion to an ischemic organ, surgeons could infuse which of the following in order to most effectively minimize superoxide formation?

A. An inhibitor of xanthine oxidase

Inhibitors of the xanthine oxidase, such as allopurinol, can diminish the capacity of this enzyme to produce superoxide. Breakdown of ATP during ischemia provides a substrate for this enzyme, namely hypoxanthine.

 Question 11

Which of the following antibody isotypes is/are NOT produced by heavy chain class switching following B cell activation?

B. IgM and IgD

IgM and IgD are produced by B cells and found on the surface before B cell activation. Following activation in response to CD40 engagement, gene rearrangement occurs, leading to synthesis of isotypes other than IgM and IgD

(Abbas pg. 204).

 Question 12

The highest numbers of eosinophils in the local tissue are seen in the following reaction:

B. Late phase of immediate hypersensitivity reaction

Eosinophils are involved in DTH, immune complex disease, or acute phase response.

 Question 13

The cytokine that primarily controls eosinophil growth, differentiation and function is:

D. IL-5

IL-5 is the cytokine that primarily controls eosinophil growth, differentiation, and function.

 Question 14

Fever may be produced by:

E. Tumor necrosis factor (TNF)

Systemic effect of TNF-á is fever along with IL-1 (Abbas pg. 253).

C3a is chemoattractant for neutrophils.

Leukotriene A4 is lipid inflammatory mediator.

IL-8 is a chemokine associated with neutrophil chemotaxis

TGF-â inhibits proliferation and differentiation of T cells and activated macrophages.

 Question 15

Idiopathic Thrombocytopenic Purpura (ITP) is an autoimmune disease caused by antibodies directed against platelet membrane proteins. This disease should be considered to be which of the following:

B. Type II: Antibody mediated immunologic disease

Type II hypersensitivity is mediated by antibodies directed against antigens present on cell surfaces or extracellular matrix. The determinants may be intrinsic to the cell membrane or matrix.

 Question 16

A patient with the following flow cytometry data for their circulating blood lymphocytes most probably is suffering from _____.

CD3 80%

CD19 < 1%

CD16 20%

E. A defect in B cell production or maturation

CD19 is a B cell cluster of differentiation antigen so if there are <1% CD19 cells the patient must have a B cell immunodeficiency.

Question 17

While being treated for wheezing and difficulty breathing, Henry Allen reports that his sister was told by her allergist that she had a condition called______________.

A. Atopy

This most common form of asthma usually begins in childhood.

Atopy refers to people with a positive family history of allergy and suggest that there is a genetic predisposition to the development of an allergic condition.

There are a number of candidate genes with the potential to influence the predisposition to atopy (e.g., HLA complex genes, genes regulating cytokine production of IL-4, IL-5 and Il-13, etc)

 Question 18

Corticosteroids, such as beclomethasone, given as a nasal spray:

D. Are not absorbed and have few systemic effects

The reason that inhaled corticosteroids are used is that they are not absorbed and targeted delivery of the drug to the site of the problem reduces the risk of developing side effects as compared to systemic (oral) administration

 Question 19

Class II MHC antigens:

E. Have grooves that bind peptides that are recognized by helper T cells.

CD8 cytotoxic T lymphocytes have a T cell receptor that recognizes processed antigen only in the context of MHC class I.

CD4 helper T lymphocytes have a T cell receptor that recognizes processed antigen only in the context of MHC class II.

 Question 20

Which of the following is found in eukaryotes but not prokaryotes?

D. Nuclear membrane

One of the differences (there are others) between prokaryotes and eukaryotes is that in eukaryotes the chromosomal DNA is organized into a membrane bound nucleus.

Question 21

A 6 month-old baby boy with a history of recurrent infections, beginning at 3 months of age, is suspected of having a severe combined immunodeficiency condition. Identify the most appropriate treatment option.

B. It would be safe to give the baby the killed Salk polio vaccine.

Live attenuated vaccines are never given to people that have severe immunodeficiencies such as SCID.

Only killed vaccine preparations may be used but very often the child lacks the ability to mount an appropriate response (protective) to the vaccine.

 Question 22

During autopsy of a patient, the pathologist notes that the left ventricular wall of the heart is markedly thickened compared to normal. Which of the following could cause this lesion?

B. Aortic valve stenosis

Stenosis in the outflow tract results in increased workload on the myocardium due to pressure overload and consequent adaptive hypertrophy of the left ventricle.

Restriction of blood flow in the lung produces pulmonary hypertension, and consequently the right ventricle would be hypertrophic in that case.

The other choices produce injury of the myocardial cells, resulting in cell death or atrophy.

(Robbins, 7th ed., pp.7-9, 590)

Question 23

You are caring for a 16 year-old boy who has suffered extensive burn injury in a house fire. His burn wounds have been treated by autografting, using skin from the patient's right thigh. Two days after harvesting the graft, the donor site on the patient's right thigh is covered by a rough, red surface. What is the medical term for this process?

C. Granulation tissue

Granulation tissue is the early repair response to a wound or other physical injury such as a burn by the proliferation of fibrocytes and small blood vessels, often forming a rough, red (vascularized) surface over the injured area.

(Robbins, 7th ed., pp.107-116)

 Question 24

Polymeric Ig receptor...

 A. facilitates the secretion of antibody (IgA)

Ig A produced by plasma cells in the lamina propria of the mucosal tissue is bound by the polymeric immunoglobulin receptor which then helps to transport the IgA to the lumen by the process of trancytosis to be released in to the mucosal secretions.

CMV or cytomegalovirus causes an asymptomatic or mononucleosis like infection in healthy individuals but can cause devestating infections in neonates and immuncompromised patients.

(Robbins pg 368)

 Question 25

The effector functions of antibodies such as opsonization and phagocytosis are mediated by

B. The Fc region

The Fc portion of an antibody can bind to specific Fc receptors on many different types of cells.

For example, IgG is bound to FC receptors of mast cells, and crosslinking of the “fixed” antibody by an allergen triggers degranulation of the mast cells.

Question 26

Coagulase production is characteristic of which bacterial species?

D. Staphylococcus aureus

Coagulase is one of the pathogenetic factors associated with Staphylococcus aureus.

Production of this protein allows binding of the bacteria to fibrin. This, in turn, allows binding of bacteria to surfaces like endothelial cells, and may protect it from opsonization and phagocytosis.

Detection of coagulase is one of the main methods of confirming the identification of S. aureus in the microbiology laboratory.

(Robbins, pp. 371-373, Mims p. 185-186.)

*************Question 27

The image below shows a photomicrograph of a liver biopsy from a patient. The cell injury demonstrated by the arrow:

D. is characterized by internucleosomal breakage in DNA

The picture illustrates a shrunken cell with pyknotic nucleus characteristic of apoptosis.One of the hallmarks of apoptosis is internucleosomal DNA cleavage, resulting in the DNA “ladder” by agarose gel electrophoresis.

(Robbins, 7th ed., pp. 26-32)

Question 28

The image below shows a scalp abscess ("carbuncle") caused by Staphylococcus aureus. The patient complained of pain and pus draining the wound. What type of necrosis would be expected to involve the underlying skin and subcutaneous tissues?

B. Liquefactive necrosis

This type of necrosis is typical of bacterial infections, characterized by pus, as described in the stem.

(Robbins, 7th ed., pp.21-22)

Question 29

A patient with a history of angina has an angiogram which shows severe stenosis of the left anterior descending coronary artery. Which territory of the heart would be most subject to developing infarction?

A. The anterior portion of the interventricular septum

The major branches of the coronary arteries supply fairly predictable terminal perfusion zones with little collateral interconnection.

(see PBL 1 and Robbins, 7th ed., pp.577-578)

Question 30

In an experiment, the left anterior descending coronary artery was ligated for a period of 15 minutes, then the vessel was re-opened. The systolic thickening fraction, a measure of myocardial function, was determined at various time points. At the time point indicated by the arrow, what would be the expected pattern of serum cardiac enzymes?

E. No cardiac enzymes will be elevated

The fact that the thickening factor (measure of myocardial function) returns to the baseline value after the occlusion indicates that there has been no significant irreversible injury (necrosis) to the myocardium, hence cardiac enzymes would not be released into the blood.

(PBL Case 1, pp. 10-11)

Question 31

During acute ischemia/reperfusion injury to the heart tissue, which of the following is the last occurrence:

C. invasion by acute inflammatory cells

Functional changes in cells, cytoskeletal disruption and morphologic changes in mitochondria are all changes that begin in the early stages after cell injury (generally within minutes), and may be present while injury is still reversible.

Outer cell membrane (sarcolemma) disruption is a sign of irreversible injury and allows leakage of intracellular contents into the extracellular space, ultimately resulting in the recruitment of acute inflammatory cells.

(Robbins, 7th ed., pp. 11-25, 53-59, 575-586)

Question 32

Match the patient history with the underlying cell process:

Question 50: Answer - caseous necrosis. The lesion described is typical in epidemiology, appearance and location of a granuloma due to Mycobacterium tuberculosis. (Robbins, 7th ed., pp. 22, 83, 381-386)

Question 51: Answer - non-pathologic apoptosis. The involution of the thymus with age is due, at least in part, to the physiologic culling of defective and self-reactive lymphocytes by apoptosis. (Robbins, 7th rd., pp. 26, 196-198, 706; Abbas, 5th ed., pp. 27-28, 151-153)

 Question 33

The MOST potent mast cell-derived bronchospastic mediator is...

D. LTD4

Leukotrienes C4, D4, and E4 play a major role in bronchiospasm (Robbins pg 726).

Platelet activating factor (PAF) causes aggregation of platelets and release of histamine and serotonin. Prostaglandin E2 (PDG2) elicit bronchoconstriction and vasodilation Leukotriene D4 (LTD4) play a major role in bronchiospasm Interleukin-3 (IL-3) IL-3 and IL-5 are involved in eosinophil recruitment.

Question 34

Match the Clinical History with the type of Cellular Adaptation:

 Question 54: (D) Hyperplasia. In this case, one of the adaptive or reactive responses to increased pressure in the pulmonary artery is proliferation (increase in number) of smooth muscle cells in the artery wall.

(Robbins, 7th ed., pp.6-7, 743-745)

Question 55: (C) Neoplasia. The high proliferation rate and invasive behavior of this lesion characterizes it as a neoplasm. Other important features are the setting of cirrhosis due to viral hepatitis and the description of the lesion as a nodule separate form the background of cirrhosis and larger than most regenerative nodules.

(Robbins, 7th ed., pp. 272-279, 882-883, 891-895, 924-926)

Question 35

A patient who camped for two weeks at the Saguaro National Monument in the Sonoran Desert region of Southwest Arizona had symptoms including fever, chills, and right-sided chest pain on deep inspiration. The patient's PPD skin test is negative. Choose the most correct description of appropriate diagnostic and therapeutic actions.

E. If three sequential early morning sputum samples are negative for acid-fast organisms, and bronchial washings are negative for fungi, AFB, and bacteria, the patient should undergo a procedure to obtain a fine needle aspirate before any treatment is begun.

Despite the rather limited clinical history provided, the point of the question is to consider a differential diagnosis that includes various causes of pneumonia, including tuberculosis and, given the location of his camping trip, Coccidiodes immitis.

The more easily obtained specimens, sputum and bronchoalveolar lavage material are negative. Before any type of treatment can be instituted, diagnostic material must be obtained, and the next most easily obtained specimen would be a fine needle aspirate.

Given the temporal relation of the camping trip in the desert and the development of his signs and symptoms, Coccidiodes immitis would be very high on the differential.

Question 36

Which of the following is a gram-negative diplococcus that is transmitted by droplet transmission and whose early symptoms can include headache, sore throat, and skin rash?

A. Neisseria meningitidis

There are only two Gram-negative diplococci listed (Neisseria meningitidis and Haemophilus influenzae).

Salmonella typhimurium is Gram-negative, but is a bacillus (and is not spread by droplet transmission).

The syndrome described is characteristic of early N. meningitidis meningitis.

H. influenzae can also cause meningitis, but is not associated with the petechial skin rash (and has a slower onset).

Question 37

Which of the following defense mechanisms is least important in the killing/inactivation of an intracellular organism?

C. Antibodies alone ity

Question 38

Which of the following species of Plasmodium can involve an exo-erythrocytic dormant phase of infection?

C. Plasmodium vivax

Hypnozoites, a dormant stage found in hepatocytes, are seen with P. vivax.

 Question 39

A patient presents to you with what appears to be an infectious disease. Which of the following is not considered in generating a microbiologic differential diagnosis and in subsequently choosing the most appropriate EMPIRIC antimicrobial therapy for your patient:

D. The patient’s ability to pay for health care

 Question 40

A particular antimicrobial agent should be selected only if its efficacy for your patient’s specific type of infection has been previously demonstrated in a randomized prospective clinical trial.

B. False

Question 41

Susceptibility testing of the bacterium that was subsequently cultured from your patient can assist you in selecting the most appropriate antimicrobial agent(s). For each of the following statements about choosing SPECIFIC antimicrobial therapy for your patient, choose either: T (true) or F (false):

All antimicrobial agents listed as “sensitive” would be expected to be equally efficacious for the patient’s infection.

B. False

Question 42

Susceptibility testing of the bacterium that was subsequently cultured from your patient can assist you in selecting the most appropriate antimicrobial agent(s). For each of the following statements about choosing SPECIFIC antimicrobial therapy for your patient, choose either: T (true) or F (false):

The expected tissue concentration of an antimicrobial agent at the patient’s specific tissue site of infection is an important predictor of clinical success.

B. True

Question 43

Susceptibility testing of the bacterium that was subsequently cultured from your patient can assist you in selecting the most appropriate antimicrobial agent(s). For each of the following statements about choosing SPECIFIC antimicrobial therapy for your patient, choose either: T (true) or F (false):

A particular antimicrobial agent listed as “resistant” could still be used if your pocket guide to antimicrobial therapy indicates that it is the “drug of choice” for your patient’s infection.

B. False

Question 44

A child of 8 months of age is brought to the pediatrician with acute sinus and respiratory infections. After reviewing the child’s records, it is apparent that he has had a history of such infections. A CBC reveals normal levels of neutrophils, basophils, eosinophils, and monocytes. However there is a complete absence of lymphocytes (no B or T cells). A defect in the expression of which of the following provides a possible explanation for the absence of both T and B lymphocytes in this child?

C. VDJ recombinase

VDJ recombinase plays a role in production of T and B cell receptors.

Question 45

A child of 8 months of age is brought to the pediatrican with a severe ear ache. A history reveals recurrent ear and respiratory infections. Lymphocyte analysis reveals that T and NK cells are slightly elevated. However, the child is shown to have no mature B cells. Laboratory analysis of his B lineage cells indicates that they are developmentally arrested at the pre-B cell stage of development. Which of the following would the laboratory use as a phenotypic marker of the pre-B cell stage of development?

D. cytoplasmic IgM heavy chain

pre-B cells are immature cell types

Question 46

Innate immunity:

Question 47

Identify the correct statement about functional inactivation of T-lymphocytes.

B. APCs constantly display self antigens present in tissues.

Question 48

Receptor editing, the process of changing receptor specificity:

D. is reactivation of Ig gene recombination to express a new light chain in B-lymphocytes that recognize self antigens in the bone marrow.

Question 49

The immune response is highly regulated in order to provide protection against invading microbes and to reduce the likelihood of responses that will damage self tissues. Select the choice that correctly describes an aspect of immune regulation.

A. Cross-linking of B-lymphocyte receptor for antigen and Fc receptor with an antigen-antibody complex inhibits B-lymphocyte differentiation.

Question 50

Immune defenses are divided into the broad categories of innate and adaptive immunity. Select the one answer that best characterizes innate immunity.

D. MHC class I molecule expression is a mechanism by which NK cells are prevented from attacking host cells

Question 51

Identify the statement that best characterizes lymph node structure and/or function.

E. Paracortex contains primarily T-lymphocytes and dendritic cells.

Question 52

Select a statement that best describes the thymus.

C. Nurse cells sustain production of progenitor T-cells by producing IL-7.

 Question 53

A child of three years old is brought to the pediatrician with a severe pyogenic (pus-forming) infection of the skin on his upper trunk and limbs. During the past two years he has had a series of recurrent pyogenic infections that have been effectively treated with antibiotics.

Based upon the nature of the recurrent infections it is suspected that the child has a defect in opsonization.

Laboratory analysis of the complement system reveals normal serum levels and normal function of all components of the complement system (including the complement regulators).

Considering the possibility that the child has a defect in bacterial opsonization, which of the following Ig isotypes would you next evaluate in the child for its intrinsic properties as an opsonin?