Question 1

What is the cause of photo contact dermatitis?&#10;A) Soap&#10;B) Acids&#10;C) Poison ivy&#10;D) Drugs or drug metabolites

Accepted Answer

Drugs or drug metabolites act as haptens and bind to MHC class II molecules on Langerhans cells. Exposure to sunlight induces structural changes in the complex of drug/MHC class I molecule, which creates an antigen that is recognized by CD4 Th1 cells. The CD4 cells release cytokines that induce skin changes.

Question 2

Patients with celiac sprue need to avoid what agent?&#10;A) Latex&#10;B) Nickel&#10;C) Gluten&#10;D) Sumac

Accepted Answer

Patients with celiac sprue have delayed-type hypersensitivity (DTH) reactions to gluten, a component of wheat, rye, barley, and oats. The DTH response damages the cells that line the gastrointestinal tract, adversely affecting the absorption of foods. Patients may experience diarrhea and even a failure to thrive due to malnutrition. Therefore, patients with celiac sprue must avoid foods that contain gluten.

Question 3

Why are Mycobacterium avium complex (MAC) infections more difficult to treat?&#10;A) Antibiotic resistance&#10;B) Antibiotics cannot reach the site of infection&#10;C) The antibiotics are so toxic that patients will not take them&#10;D) MAC organisms can form spores that protect them from an immune response

Accepted Answer

MAC organisms are resistant to many antibiotics, so there are not many treatment options.

Question 4

What is an advantage of in vitro testing over the PPD skin test for TB?
I. The test is more accurate
II. The test can be completed in 1 day
III. The test is not affected by prior TB vaccinations

A) I only
B) III only
C) I and II
D) II and III
E) I, II, and III

Accepted Answer

All of these are True regarding the in vitro testing option for TB. The test is more accurate than the skin test because there is no reader, which means there is no potential for bias or confusion in interpretation. The test can be completed in 1 day and does not require the patient to come back a second time for a reading. Finally, the test detects antigens that are not present in the vaccine.

Question 5

Which of the following can be found inside a granuloma?&#10;A) Basophils&#10;B) Eosinophils&#10;C) Neutrophils&#10;D) Macrophages

Accepted Answer

Macrophages, lymphocytes, and fibroblasts are encapsulated with the infectious material in a final attempt to contain the infection.

Question 6

Which of the following is/are considered a genetic factor that increases susceptibility to mycobacterial infections?
I. Defect in TNF-a receptor
II. Defect in vitamin D receptor
III. Defect in interferon-g receptor

A) I only
B) III only
C) I and II
D) II and III
E) I, II, and III

Accepted Answer

Increased susceptibility to TB infection has been associated with defects in the vitamin D receptor and the interferon-ã receptor. TNF-a causes a significant amount of lung damage in TB, so there is no defect in that receptor.

Question 7

Defects in NRAMPs cause:&#10;A) Phagosome dysfunction&#10;B) Disruption of protein synthesis&#10;C) Inability to package and release antibodies&#10;D) Defective interactions between CD4 T cells and antigen-presenting cells (APCs)

Accepted Answer

NRAMP1 reduces the pH of the phagosome, which is a key part of bacterial killing. NRAMP2 is an efflux pump that transports iron and other cations out of the phagosome. Defects in these two components lead to ineffective killing in the phagosome, and the bacteria can escape and establish infection inside the macrophage.

Question 8

What is the difference between granulomas found in coccidioidomycosis and TB?&#10;A) There are no T cells present in coccidioidomycosis granulomas.&#10;B) There are B cells present only in coccidioidomycosis granulomas.&#10;C) There are no fibroblasts present in coccidioidomycosis granulomas.&#10;D) There are lymphocytes present only in coccidioidomycosis granulomas.

Accepted Answer

The only difference in granulomas found in coccidioidomycosis patients is that they contain B cells in addition to the other immune cells normally found in granulomas of TB patients.

Question 9

Which of the following is present in bat droppings, putting cavers at risk for this disease?&#10;A) Coccidioides immitis&#10;B) Histoplasma capsulatum&#10;C) Mycobacterium tuberculosis&#10;D) Mycobacterium avium complex (MAC)

Accepted Answer

H. capsulatum is found in bat and bird droppings, putting anyone who comes into contact with the disturbed droppings at risk for histoplasmosis, including cavers, farmers, landscapers, and construction workers. Immunocompromised patients are also at risk for acquiring histoplasmosis.

Question 10

What is the difference between a reaction to poison ivy and other delayed-type hypersensitivity reactions?&#10;A) The poison ivy reaction is solely a CD8 response.&#10;B) The poison ivy reaction is solely mediated by IgG.&#10;C) The poison ivy reaction is solely an NK cell response.&#10;D) The poison ivy reaction is solely a macrophage response.

Accepted Answer

Whereas other delayed-type hypersensitivity reactions involve several immune cell types, the reaction to poison ivy only involves activation of CD8 T cells. The CD8 T cells kill any host cell that has urushiol on the cell surface.

Question 11

Why is a positive PPD skin test not sufficient to determine if a patient has active TB?&#10;A) The skin test does not test for all strains.&#10;B) There are many false positive test results.&#10;C) Only the latent form gives a positive skin test.&#10;D) The positive skin test only indicates previous exposure.

Accepted Answer

The answer of Why is a positive PPD skin test...

Question 12

Which of the following is a virulence factor and drug target for Mycobacterium tuberculosis?&#10;A) Capsule&#10;B) NRAMP1&#10;C) Ergosterol&#10;D) Mycolic acid

Accepted Answer

The answer of Which of the following is a virulence...

Question 13

The main organ target for Coccidioides immitis is:&#10;A) Lung&#10;B) Liver&#10;C) Heart&#10;D) Muscles

Accepted Answer

The answer of The main organ target for Coccidioides immitis...

Question 14

What role does lipoarabinomannan play in the immune response triggered by tuberculosis (TB) infection?&#10;A) Stimulates production of IL-10&#10;B) Stimulates production of TNF-a&#10;C) Stimulates production of interferon-g&#10;D) Stimulates production of reactive oxygen species (ROS)

Accepted Answer

The answer of What role does lipoarabinomannan play in the...

Question 15

In which stage of TB infection does lung necrosis caused by macrophage-derived reactive oxygen species (ROS) begin?&#10;A) The first phase&#10;B) The second phase&#10;C) The third phase&#10;D) The final phase

Accepted Answer

The answer of In which stage of TB infection does...

Deck 19: Delayed Type Hypersensitivity Reactions