Q: Which of the following equations best represents the relationship between antigen-antibody complexes and inflammation in Type III hypersensitivity?

$$\text{Antigen} + \text{Antibody} \rightarrow \text{Immune Complex} \rightarrow \text{Complement Activation} \rightarrow \text{Neutrophil Enzyme Release} \rightarrow \text{Inflammation}$$

Question 1

Which of the following best describes the mechanism of Type I hypersensitivity upon second exposure to an allergen?

Accepted Answer

IgE antibodies bound to mast cells cross-link with the allergen, causing degranulation and histamine release.

Question 2

A patient experiences a sudden drop in blood pressure and difficulty breathing after eating peanuts. Which treatment is most appropriate for this scenario?

Accepted Answer

Administration of epinephrine to induce vasoconstriction and increase blood pressure.

Question 3

Which of the following equations best represents the relationship between antigen-antibody complexes and inflammation in Type III hypersensitivity?

Accepted Answer

$$	ext{Antigen} + 	ext{Antibody} ightarrow 	ext{Immune Complex} ightarrow 	ext{Complement Activation} ightarrow 	ext{Neutrophil Enzyme Release} ightarrow 	ext{Inflammation}$$

Question 4

A woman with blood type O receives a transfusion of type A blood. What is the most likely outcome?

Accepted Answer

Her anti-A antibodies will attack the transfused cells, causing hemolysis.

Question 5

Which of the following best explains why allergy shots (immunotherapy) can reduce allergic reactions?

Accepted Answer

They stimulate the production of IgG, which neutralizes the allergen before it binds to IgE.

Question 6

Which hypersensitivity type is primarily mediated by cytotoxic T cells and is responsible for contact dermatitis, such as that caused by poison ivy?

Accepted Answer

Type IV hypersensitivity

Question 7

A newborn develops hemolytic disease due to Rh incompatibility. Which sequence of events best explains this condition?

Accepted Answer

The mother is Rh-, the fetus is Rh+, and maternal anti-Rh antibodies cross the placenta and destroy fetal red blood cells.

Question 8

Which of the following is a primary (congenital) immunodeficiency disorder characterized by non-functional T and B cells?

Accepted Answer

Severe Combined Immunodeficiency Disease (SCID)

Question 9

Which autoimmune disease is characterized by antibodies against chromatin, leading to immune complex deposition in joints, kidneys, and blood vessels?

Accepted Answer

Lupus

Question 10

Which of the following best describes the mechanism of action of cyclosporin in transplant patients?

Accepted Answer

It prevents clonal expansion of T cells, suppressing the immune response.

Question 11

Which of the following is a correct sequence of events in the development of allergic contact dermatitis due to poison ivy?

Accepted Answer

First contact: memory T cells are produced; second contact: cytotoxic T cells destroy altered skin cells.

Question 12

Which of the following best explains why patients with AIDS are highly susceptible to infections?

Accepted Answer

HIV infection leads to the destruction of T helper cells, impairing both antibody and cell-mediated immune responses.

Question 13

Which of the following is a real-life example of Type II hypersensitivity?

Accepted Answer

Hemolytic transfusion reaction due to mismatched blood transfusion

Question 14

Which of the following best describes the pathogenesis of rheumatoid arthritis?

Accepted Answer

IgM, IgG, and complement act against collagen in the joints, causing chronic inflammation.

Question 15

Which of the following is a plausible outcome if a patient with type B blood receives type AB blood?

Accepted Answer

The patient's anti-A antibodies will attack the A antigens on the transfused cells.

Question 16

Which of the following best explains the role of complement in Type III hypersensitivity?

Accepted Answer

Complement activation attracts neutrophils, which release enzymes that damage tissues.

Question 17

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

Accepted Answer

It involves a delayed response mediated by T cells.

Question 18

Which of the following best describes the mechanism of graft-versus-host disease?

Accepted Answer

Donor cytotoxic T cells attack the recipient's body cells.

Question 19

Which of the following best explains why patients receiving immunosuppressive drugs after transplantation are at increased risk of infection?

Accepted Answer

Immunosuppressive drugs inhibit the clonal expansion of T cells, reducing the body's ability to fight infections.

Immune System Disorders: Hypersensitivity, Autoimmunity, and Immunodeficiency

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