$$\text{Antigen} + \text{Antibody} \rightarrow \text{Immune Complex} \xrightarrow{\text{Complement}} \text{Inflammation}$$

Question 1

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

Accepted Answer

Antigen binds to IgE on mast cells, causing degranulation and release of inflammatory mediators.

Question 2

A patient experiences acute anaphylaxis after eating peanuts. Which treatment is most appropriate for immediate intervention?

Accepted Answer

Epinephrine injection

Question 3

Which cell type is primarily responsible for the release of histamine during an allergic reaction?

Accepted Answer

Mast cells

Question 4

A person with type AB blood receives a transfusion from a type O donor. Why is this transfusion safe?

Accepted Answer

Type O blood lacks A and B antigens, so it does not trigger an immune response in the recipient.

Question 5

Which hypersensitivity type is associated with immune complex deposition in tissues, such as in glomerulonephritis?

Accepted Answer

Type III (immune complex–mediated) hypersensitivity

Question 6

A woman who is Rh-negative gives birth to an Rh-positive baby. In a subsequent pregnancy, what is the risk if she does not receive RhoGAM?

Accepted Answer

Her immune system may attack the fetal red blood cells, causing hemolytic disease of the newborn.

Question 7

Which of the following is a characteristic clinical sign of systemic lupus erythematosus (SLE)?

Accepted Answer

Butterfly-shaped facial rash

Question 8

Which equation best represents the relationship between antigen-antibody complexes and complement activation in Type III hypersensitivity?

Accepted Answer

$$	ext{Antigen} + 	ext{Antibody} ightarrow 	ext{Immune Complex} \xrightarrow{	ext{Complement}} 	ext{Inflammation}$$

Question 9

Which autoimmune disease is characterized by cytotoxic T cell destruction of myelin sheaths in the central nervous system?

Accepted Answer

Multiple sclerosis (MS)

Question 10

A patient develops a red, hard swelling at the site of a tuberculin skin test 48 hours after injection. What type of hypersensitivity is this?

Accepted Answer

Type IV (delayed or cell-mediated) hypersensitivity

Question 11

Which of the following best explains why immunosuppressive drugs are important in organ transplantation?

Accepted Answer

They reduce the likelihood of graft rejection by suppressing the recipient’s immune response.

Question 12

Which of the following is a plausible reason why Koch’s postulates cannot be used to determine the cause of Graves’ disease?

Accepted Answer

Graves’ disease is not caused by a single infectious microorganism but by an autoimmune response.

Question 13

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

Accepted Answer

They block histamine receptors, reducing the effects of histamine released during allergic reactions.

Question 14

Which of the following is a common cause of acquired immunodeficiency?

Accepted Answer

Malnutrition

Question 15

A patient with rheumatoid arthritis is treated with glucocorticoids. What is the primary effect of this treatment?

Accepted Answer

Reduction of inflammation

Question 16

Which of the following best explains molecular mimicry as a cause of autoimmune disease?

Accepted Answer

Microbial antigens resemble self-antigens, leading to cross-reactive immune responses.

Question 17

Which of the following is a distinguishing feature of Type IV hypersensitivity compared to the other types?

Accepted Answer

It is mediated by T cells rather than antibodies.

Question 18

Which of the following best describes the pathogenesis of autoimmune hemolytic anemia?

Accepted Answer

Antibodies are produced against red blood cells, leading to their destruction.

Question 19

Which of the following equations best represents the destruction of red blood cells in a transfusion reaction?

Accepted Answer

$$	ext{Antibody} + 	ext{Foreign RBC Antigen} ightarrow 	ext{Complement Activation} ightarrow 	ext{Hemolysis}$$

Question 20

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

Accepted Answer

Type IV hypersensitivity; T cell-mediated response

Immune Disorders: Hypersensitivities, Autoimmune Diseases, and Immunodeficiencies

Study Guide - Practice Questions