Q: A patient with type O- blood is considered the universal donor. Which equation best represents the absence of antigens on their red blood cells?

$$\text{Antigen}_{\text{O-}} = 0$$

Question 1

Which of the following best describes a primary (congenital) immunodeficiency?

Accepted Answer

An inborn error affecting one or more immune system factors, present from birth.

Question 2

A patient is diagnosed with systemic lupus erythematosus. Which type of hypersensitivity reaction is most closely associated with this disease, and what is the underlying mechanism?

Accepted Answer

Type III; IgG or IgM antibodies bind to soluble antigens forming immune complexes that deposit in tissues.

Question 3

Which of the following statements about hemolytic disease of the newborn (HDN) is correct?

Accepted Answer

HDN is prevented by administering Rh(D) immunoglobulin to the Rh- mother during her first pregnancy with an Rh+ fetus.

Question 4

A patient receives a blood transfusion and develops fever, chills, and lower back pain within hours. Which hypersensitivity reaction is most likely responsible, and what is the mechanism?

Accepted Answer

Type II; IgG or IgM antibodies bind to antigens on donor red blood cells, activating complement and causing cell lysis.

Question 5

Which of the following is NOT a mediator of Type I hypersensitivity reactions?

Accepted Answer

T cytotoxic cells

Question 6

A patient with type O- blood is considered the universal donor. Which equation best represents the absence of antigens on their red blood cells?

Accepted Answer

$$	ext{Antigen}_{	ext{O-}} = 0$$

Question 7

Which of the following best explains the hygiene hypothesis?

Accepted Answer

Reduced biodiversity of normal microbiota in developed countries increases risk for autoimmune disorders and allergies.

Question 8

Which of the following is a localized autoimmune disorder?

Accepted Answer

Rheumatoid arthritis

Question 9

A patient develops muscle weakness and fatigue due to antibodies inactivating acetylcholine receptors at the neuromuscular junction. Which disease and hypersensitivity type is this?

Accepted Answer

Myasthenia gravis; Type II hypersensitivity (non-cytolytic)

Question 10

Which of the following is TRUE regarding the erythrocyte sedimentation rate (ESR) test?

Accepted Answer

ESR reflects how long it takes for red blood cells to separate from plasma.

Question 11

Which of the following viruses is most closely associated with the development of type I diabetes as a possible trigger?

Accepted Answer

Coxsackievirus B

Question 12

During a skin prick test, a patient develops a wheal and flare lesion. What does this indicate?

Accepted Answer

The patient has an allergy to the tested allergen, mediated by IgE.

Question 13

Which of the following best describes the mechanism of desensitization immunotherapy for allergies?

Accepted Answer

Stimulates regulatory T cells to promote TH1 response and IgG production, limiting IgE-allergen complexes.

Question 14

Which of the following is NOT a mediator of Type III hypersensitivity reactions?

Accepted Answer

T helper cells

Question 15

A patient develops serum sickness after receiving antivenom. Which equation best represents the formation of immune complexes in this reaction?

Accepted Answer

$$	ext{Immune Complex} = 	ext{IgG} + 	ext{Soluble Antigen}$$

Question 16

Which of the following is a nonautoimmune Type IV hypersensitivity reaction?

Accepted Answer

Tuberculin skin test

Question 17

Which of the following transplant types is least likely to be rejected?

Accepted Answer

Autograft

Question 18

Which of the following sites in the body is considered immune-privileged, making transplants there less likely to be rejected?

Accepted Answer

Eye

Question 19

A patient receives a bone marrow transplant and develops graft-versus-host disease. Which equation best represents the immune response?

Accepted Answer

$$	ext{Graft Immune Cells} ightarrow 	ext{Attack Host Tissues}$$

Question 20

Which molecule is most likely to trigger a nonautoimmune Type IV hypersensitivity reaction?

Accepted Answer

Hapten

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