Question 1

A patient experiences a severe allergic reaction within minutes of being stung by a bee, resulting in systemic symptoms such as difficulty breathing and a drop in blood pressure. Which type of hypersensitivity reaction is this, and what is the primary immunoglobulin involved?

Accepted Answer

Type I hypersensitivity; IgE

Question 2

A child develops hemolytic disease of the newborn due to Rh incompatibility. Which of the following best explains the immunological mechanism behind this condition?

Accepted Answer

Maternal IgG antibodies target fetal red blood cells expressing the Rh antigen, leading to cell lysis

Question 3

Which of the following best describes the hygiene hypothesis as it relates to the development of allergies?

Accepted Answer

A lack of early microbial exposure impairs immune system training, increasing susceptibility to allergies

Question 4

A patient receives a blood transfusion with incompatible blood and develops fever, hemoglobinuria, and jaundice. Which immunological process is primarily responsible for these symptoms?

Accepted Answer

Type II hypersensitivity mediated by IgG and complement

Question 5

Which of the following is the correct equation for determining the possible genotypes for blood type A in the ABO blood group system?

Accepted Answer

$$A A 	ext{ or } A O$$

Question 6

A patient with systemic lupus erythematosus (SLE) produces autoantibodies against nuclear components, leading to widespread inflammation. Which type of hypersensitivity is primarily involved in SLE?

Accepted Answer

Type III hypersensitivity

Question 7

A positive tuberculin skin test is an example of which type of hypersensitivity reaction, and what is the main immune cell involved?

Accepted Answer

Type IV hypersensitivity; T cells

Question 8

Which of the following best explains why type O blood is considered the universal donor?

Accepted Answer

Type O blood lacks A and B antigens on the red blood cell surface

Question 9

A patient develops contact dermatitis after exposure to poison ivy. Which of the following best describes the immunological mechanism?

Accepted Answer

T-cell-mediated delayed hypersensitivity

Question 10

Which of the following is a plausible explanation for the development of autoimmunity via molecular mimicry?

Accepted Answer

Microbial antigens resemble self-antigens, leading to cross-reactive immune responses against host tissues

Question 11

A patient with DiGeorge syndrome is highly susceptible to viral and fungal infections. Which of the following best explains the underlying immunological defect?

Accepted Answer

Absence of thymus resulting in T cell deficiency

Question 12

Which of the following best describes the pathogenesis of post-streptococcal glomerulonephritis?

Accepted Answer

Immune complex deposition in the glomerular basement membrane, activating complement and attracting neutrophils

Question 13

A patient with myasthenia gravis has muscle weakness due to antibodies targeting acetylcholine receptors. Which type of hypersensitivity is this, and what is the main effect?

Accepted Answer

Type II hypersensitivity; antibody-mediated receptor blockade

Question 14

Which of the following equations correctly represents the inheritance of the Rh factor?

Accepted Answer

$$Rh^+ = 	ext{at least one dominant allele}$$

Question 15

A patient with severe combined immunodeficiency (SCID) is unable to mount effective immune responses. Which of the following best describes the immunological defect in SCID?

Accepted Answer

Deficiency of both B and T cells

Question 16

Which of the following best explains why a patient with AIDS is susceptible to opportunistic infections?

Accepted Answer

Depletion of T helper cells impairs both humoral and cellular immunity

Question 17

A patient with rheumatoid arthritis develops joint inflammation due to immune complexes and T cell activation. Which types of hypersensitivity are involved in this disease?

Accepted Answer

Type II, III, and IV

Question 18

Which of the following best describes the mechanism of action for antihistamines in the treatment of allergies?

Accepted Answer

They inhibit the binding of histamine to its receptors on target cells

Question 19

A patient with type 1 diabetes mellitus has cytotoxic T cells attacking pancreatic beta cells. Which type of hypersensitivity is this, and what is the result?

Accepted Answer

Type IV hypersensitivity; destruction of insulin-producing cells

Question 20

Which of the following best explains why a bone marrow transplant from an unrelated donor is more likely to be rejected than one from an identical twin?

Accepted Answer

Unrelated donors are less likely to share similar MHC (HLA) markers, leading to T cell-mediated rejection

Disorders in Immunity: Hypersensitivity, Autoimmunity, and Immunodeficiency

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