Question 1

Which of the following best defines hypersensitivity in the context of immunology?

Accepted Answer

An exaggerated or inappropriate immune response to an antigen that results in tissue damage.

Question 2

A patient experiences rapid onset of difficulty breathing, hypotension, and widespread hives after a bee sting. Which mechanism is primarily responsible for these symptoms?

Accepted Answer

Release of histamine and other mediators from mast cells due to IgE cross-linking.

Question 3

Which of the following best distinguishes systemic anaphylaxis from localized anaphylaxis?

Accepted Answer

Systemic anaphylaxis is a life-threatening reaction affecting multiple organ systems, while localized anaphylaxis is restricted to a specific tissue or organ.

Question 4

During an allergy skin test, a small amount of allergen is injected into the skin. A positive reaction is indicated by which of the following?

Accepted Answer

Immediate wheal and flare reaction due to local mast cell degranulation.

Question 5

Desensitization therapy for allergies involves repeated exposure to increasing doses of allergen. What is the primary immunological goal of this therapy?

Accepted Answer

To stimulate the production of blocking IgG antibodies that neutralize the allergen before it binds to IgE.

Question 6

A patient develops hemolytic anemia after taking a new medication. Which type of hypersensitivity reaction is most likely involved?

Accepted Answer

Type II (cytotoxic) hypersensitivity, where the drug binds to red blood cells and is targeted by antibodies.

Question 7

A patient with blood type A receives a transfusion of type B blood. Which immunological mechanism is responsible for the resulting transfusion reaction?

Accepted Answer

Type II hypersensitivity, where anti-B antibodies in the recipient bind to B antigens on donor red blood cells, leading to complement-mediated lysis.

Question 8

Hemolytic disease of the newborn (HDN) can occur when an Rh-negative mother carries an Rh-positive fetus. Which of the following best explains the immunological basis of HDN?

Accepted Answer

Maternal anti-Rh IgG antibodies cross the placenta and mediate destruction of fetal red blood cells.

Question 9

Which of the following best describes the mechanism of immune complex (Type III) hypersensitivity reactions?

Accepted Answer

Antigen-antibody complexes deposit in tissues, activating complement and attracting neutrophils, leading to inflammation and tissue damage.

Question 10

A patient develops a skin rash 48 hours after contact with poison ivy. Which type of hypersensitivity is this, and what is the primary mechanism?

Accepted Answer

Type IV hypersensitivity; T cell-mediated delayed response.

Question 11

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

Accepted Answer

Clonal deletion of self-reactive lymphocytes during development.

Question 12

Which of the following is an example of a cell-mediated autoimmune disease?

Accepted Answer

Type I diabetes mellitus

Question 13

The HLA complex is important in transplantation because:

Accepted Answer

It encodes proteins that present antigens to T cells, influencing tissue compatibility and disease susceptibility.

Question 14

A kidney transplant is rejected by the recipient's immune system. Which process is primarily responsible for this rejection?

Accepted Answer

Recipient T cells recognize donor HLA antigens as foreign and initiate an immune response.

Question 15

Which of the following best defines a privileged site in transplantation immunology?

Accepted Answer

A site in the body where immune responses are limited, allowing for successful transplantation with reduced risk of rejection.

Question 16

Which type of graft involves transplantation between genetically identical individuals?

Accepted Answer

Isograft

Question 17

Graft-versus-host disease (GVHD) is most likely to occur under which of the following conditions?

Accepted Answer

Donor immune cells in the graft attack the recipient's tissues.

Question 18

Which of the following is a common strategy to prevent rejection of a transplanted organ?

Accepted Answer

Administering immunosuppressive drugs to the recipient.

Question 19

Which of the following is a mechanism by which cancer cells evade the immune system?

Accepted Answer

Secreting immunosuppressive cytokines that inhibit T cell activity.

Question 20

Which of the following is an example of immunotherapy for cancer?

Accepted Answer

Administration of monoclonal antibodies targeting tumor antigens.

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

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