Question 1

Which of the following best describes the mechanism of a Type I (anaphylactic) hypersensitivity reaction?

Accepted Answer

Antigen binds to IgE on mast cells, causing degranulation and release of mediators such as histamine.

Question 2

A patient receives a bee sting and within minutes develops widespread hives, difficulty breathing, and hypotension. What is the most appropriate immediate treatment?

Accepted Answer

Epinephrine injection

Question 3

Which antibody class is primarily responsible for mediating anaphylactic reactions?

Accepted Answer

IgE

Question 4

A child with a peanut allergy undergoes desensitization therapy. What is the immunological basis for this treatment?

Accepted Answer

Induction of IgG blocking antibodies that intercept the allergen before it binds to IgE

Question 5

Which of the following is a key difference between systemic and localized anaphylaxis?

Accepted Answer

Systemic anaphylaxis affects the entire body and can cause shock, while localized anaphylaxis is restricted to a specific tissue or organ.

Question 6

A patient with type O blood receives type A blood in a transfusion. Which hypersensitivity reaction is most likely to occur?

Accepted Answer

Type II (cytotoxic) hypersensitivity

Question 7

Hemolytic disease of the newborn is prevented by administering RhoGAM to Rh-negative mothers. What is the mechanism of action of RhoGAM?

Accepted Answer

It contains anti-Rh antibodies that destroy fetal Rh+ red blood cells before the mother can mount an immune response.

Question 8

Which of the following best explains why immune complex diseases (Type III hypersensitivity) cause tissue damage?

Accepted Answer

Immune complexes deposit in tissues, activate complement, and attract neutrophils that release enzymes causing inflammation.

Question 9

A patient develops a red, itchy rash 48 hours after exposure to poison ivy. Which type of hypersensitivity reaction is this?

Accepted Answer

Type IV (delayed cell-mediated) hypersensitivity

Question 10

Which of the following is a mechanism for self-tolerance in the immune system?

Accepted Answer

Clonal deletion of self-reactive T cells in the thymus

Question 11

Multiple sclerosis is an example of which type of autoimmune disease?

Accepted Answer

Cytotoxic autoimmune disease

Question 12

Which organ is primarily affected in Graves’ disease?

Accepted Answer

Thyroid gland

Question 13

Which of the following best describes the role of the HLA complex in transplantation?

Accepted Answer

It encodes self-antigens that must be matched between donor and recipient to reduce transplant rejection.

Question 14

Which type of transplant is most likely to provoke a hyperacute rejection?

Accepted Answer

Xenotransplantation product

Question 15

A patient receives a bone marrow transplant and develops a severe rash, diarrhea, and liver dysfunction. What is the most likely explanation?

Accepted Answer

Graft-versus-host disease caused by donor immune cells attacking the recipient

Question 16

Which cytokine is a common target of immunosuppressant drugs used to prevent transplant rejection?

Accepted Answer

$$IL-2$$

Question 17

Which of the following is a congenital immunodeficiency?

Accepted Answer

DiGeorge syndrome (thymic aplasia)

Question 18

Which cell type is the primary target of HIV infection?

Accepted Answer

$$CD4^+ T $$helper cells

Question 19

Which of the following best explains why reverse transcriptase, integrase, and protease are good targets for HIV chemotherapy?

Accepted Answer

They are essential viral enzymes not found in human cells.

Question 20

Which of the following is the most common mode of HIV transmission worldwide?

Accepted Answer

Heterosexual contact

Disorders Associated with the Immune System: Hypersensitivity, Autoimmunity, Transplantation, Immunodeficiencies, and AIDS

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