$$\text{Ag} + \text{Ab} \rightarrow \text{Ag-Ab complex} \rightarrow \text{Complement activation}$$

$$\text{Allergen} + \text{IgE-FcR} \rightarrow \text{Cross-linking} \rightarrow \text{Ca}^{2+} \uparrow \rightarrow \text{Degranulation}$$

Question 1

Which of the following best describes the difference between an allergy and an intolerance?

Accepted Answer

Allergy involves an immune response to a harmless substance, while intolerance does not involve the immune system.

Question 2

According to the Hygiene Hypothesis, which factor is most likely to increase the risk of developing allergies?

Accepted Answer

Reduced exposure to microbes and parasites during infancy.

Question 3

Which immune cell is primarily responsible for the immediate symptoms of Type I hypersensitivity?

Accepted Answer

Mast cell

Question 4

A patient experiences swelling, itching, and difficulty breathing within minutes of a bee sting. What is the most likely diagnosis?

Accepted Answer

Anaphylactic shock

Question 5

Which cytokines are most associated with the promotion of Th2 cells in allergic responses?

Accepted Answer

$$IL-4$$ and $$IL-13$$

Question 6

What is the role of IgE in the normal immune response?

Accepted Answer

IgE binds to parasites such as helminths and facilitates their killing by eosinophils.

Question 7

Which of the following is a common environmental factor that increases allergy risk?

Accepted Answer

Exposure to pollution

Question 8

Which of the following best explains the mechanism of mast cell degranulation during a Type I hypersensitivity reaction?

Accepted Answer

Cross-linking of membrane-bound IgE by allergen leads to intracellular phosphorylation and increased $$Ca^{2+}$$ concentration.

Question 9

Which of the following is NOT a typical symptom of an allergic reaction?

Accepted Answer

High fever

Question 10

A patient with persistent allergic asthma is treated with omalizumab. What is the mechanism of action of this therapy?

Accepted Answer

Omalizumab binds to free IgE, preventing it from attaching to mast cells and basophils.

Question 11

Which of the following is a clinical example of Type II hypersensitivity?

Accepted Answer

Hemolytic disease of the newborn

Question 12

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

Accepted Answer

$$	ext{Ag} + 	ext{Ab} ightarrow 	ext{Ag-Ab complex} ightarrow 	ext{Complement activation}$$

Question 13

Which cell type is most involved in the late phase reaction of allergy?

Accepted Answer

Eosinophils

Question 14

Which of the following is a key feature of Type IV hypersensitivity?

Accepted Answer

T cell-mediated tissue damage

Question 15

A patient develops joint pain, rash, and proteinuria after receiving horse serum. What is the most likely diagnosis?

Accepted Answer

Serum sickness (Type III hypersensitivity)

Question 16

Which of the following is a mechanism by which allergen-specific immunotherapy (AIT) reduces allergic symptoms?

Accepted Answer

Induction of immune tolerance by increasing allergen-specific Tregs and decreasing IgE levels.

Question 17

Which of the following is a common cause of IgE-mediated allergic reactions?

Accepted Answer

Pollen from trees and grasses

Question 18

Which equation best describes the process of mast cell degranulation after allergen exposure?

Accepted Answer

$$	ext{Allergen} + 	ext{IgE-FcR} ightarrow 	ext{Cross-linking} ightarrow 	ext{Ca}^{2+} \uparrow ightarrow 	ext{Degranulation}$$

Question 19

Which of the following is a major economic impact of allergies in industrialized nations?

Accepted Answer

Allergies cost tens of billions of dollars annually in healthcare expenses.

Question 20

Which of the following is a diagnostic challenge in allergy medicine?

Accepted Answer

Superficial signs may not be specific to allergy and require detailed investigations.

Hypersensitivity and Allergy: Mechanisms, Types, and Clinical Implications

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