Question 1

Which of the following best describes the mechanism of Type I (immediate) hypersensitivity reactions?

Accepted Answer

IgE antibodies bind to mast cells and basophils, leading to degranulation and release of inflammatory mediators upon re-exposure to the allergen.

Question 2

A patient receives a blood transfusion with incompatible blood type and develops hemolysis, kidney failure, and systemic shock. Which hypersensitivity type is responsible?

Accepted Answer

Type II (cytotoxic) hypersensitivity

Question 3

Which inflammatory molecule released from mast cells is primarily responsible for increased vascular permeability and smooth muscle contraction in allergic reactions?

Accepted Answer

Histamine

Question 4

A child develops a red, hard swelling at the site of a tuberculin skin test 48 hours after injection. Which immune mechanism is primarily responsible?

Accepted Answer

Memory T cell-mediated delayed inflammation

Question 5

Which of the following is a key feature of systemic lupus erythematosus (SLE)?

Accepted Answer

Autoantibodies against DNA form immune complexes that deposit in tissues.

Question 6

Which of the following best explains why children raised in rural environments with animals have lower rates of allergies, according to the hygiene hypothesis?

Accepted Answer

Early immune stimulation reduces the likelihood of developing Type I hypersensitivities.

Question 7

A patient with a history of multiple blood transfusions develops antibodies against their own red blood cells, resulting in severe anemia. This is an example of:

Accepted Answer

Autoimmune hemolytic anemia

Question 8

Which of the following is a characteristic of HIV that makes vaccine development challenging?

Accepted Answer

HIV has high antigenic variability due to rapid mutation rates.

Question 9

Which laboratory finding is most consistent with a diagnosis of AIDS?

Accepted Answer

Low levels of CD4 T cells and presence of antibodies against HIV

Question 10

Which of the following best describes the mechanism of action of RhoGAM in preventing hemolytic disease of the newborn?

Accepted Answer

It neutralizes fetal Rh antigens before the mother’s immune system can respond.

Question 11

Which of the following is a primary immunodeficiency disease characterized by a lack of both T cells and B cells?

Accepted Answer

Severe combined immunodeficiency (SCID)

Question 12

A patient presents with joint pain and swelling. Laboratory tests reveal immune complexes in the synovial fluid. Which hypersensitivity type is most likely involved?

Accepted Answer

Type III hypersensitivity

Question 13

Which of the following best explains why antihistamines are effective in treating mild allergic reactions?

Accepted Answer

They neutralize histamine released from mast cells, reducing symptoms.

Question 14

Which of the following is a real-world example of a Type IV hypersensitivity reaction?

Accepted Answer

Contact dermatitis from poison ivy exposure

Question 15

Which of the following best describes the pathogenesis of glomerulonephritis in Type III hypersensitivity?

Accepted Answer

Immune complexes deposit in glomeruli, activating complement and causing inflammation

Question 16

Which of the following is a common cause of secondary (acquired) immunodeficiency?

Accepted Answer

HIV infection leading to depletion of CD4 T cells

Question 17

Which of the following is a key difference between Type II and Type III hypersensitivity reactions?

Accepted Answer

Type II involves antibodies binding to cell surface antigens, while Type III involves immune complexes depositing in tissues.

Question 18

Which of the following best describes the effect of corticosteroids in the treatment of autoimmune diseases?

Accepted Answer

They suppress the immune response, reducing inflammation and autoantibody formation.

Question 19

Which of the following behaviors is most likely to increase the risk of HIV transmission?

Accepted Answer

Sharing needles for intravenous drug use

Question 20

Which of the following best explains why immunotherapy (allergy shots) can reduce allergic reactions?

Accepted Answer

They stimulate the production of IgG antibodies that bind allergens before they can bind to IgE on mast cells.

Immune Disorders: Hypersensitivities, Autoimmunity, and Immunodeficiency

Study Guide - Practice Questions

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