Q: Which of the following equations best represents the relationship between antigen, IgE, and mast cell activation in anaphylactic reactions?

$$\text{Antigen} + \text{IgE} \xrightarrow{\text{binds}} \text{Mast Cell Activation}$$

Question 1

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

Accepted Answer

IgE antibodies bind to mast cells and basophils, leading to degranulation and release of mediators such as histamine.

Question 2

A patient receives a blood transfusion and develops chills, fever, and hemolysis within hours. Which hypersensitivity type is most likely responsible?

Accepted Answer

Type II (Cytotoxic)

Question 3

Which of the following is a key mediator released during mast cell degranulation in an anaphylactic reaction, and what is its primary effect?

Accepted Answer

Histamine; causes vasodilation and increased capillary permeability

Question 4

A child is tested for allergies by injecting small amounts of various antigens under the skin, resulting in localized wheals. What is the immunological basis for this reaction?

Accepted Answer

Type I hypersensitivity involving IgE-mediated mast cell degranulation

Question 5

Which of the following best explains why a second Rh+ pregnancy in an Rh– mother is at risk for hemolytic disease of the newborn (HDNB)?

Accepted Answer

The mother’s anti-Rh IgG antibodies cross the placenta and destroy fetal RBCs.

Question 6

A patient develops a red, itchy rash after contact with poison ivy. Which hypersensitivity type is responsible, and what is the key immune cell involved?

Accepted Answer

Type IV; T cells

Question 7

Which of the following equations best represents the relationship between antigen, IgE, and mast cell activation in anaphylactic reactions?

Accepted Answer

$$	ext{Antigen} + 	ext{IgE} \xrightarrow{	ext{binds}} 	ext{Mast Cell Activation}$$

Question 8

Which of the following is a characteristic feature of Type III (immune complex) hypersensitivity reactions?

Accepted Answer

Immune complexes deposit in tissues, activating complement and causing inflammation.

Question 9

A patient with systemic lupus erythematosus (SLE) is most likely to experience which of the following pathological processes?

Accepted Answer

Formation of immune complexes that deposit in the kidneys

Question 10

Which of the following best describes the mechanism of drug-induced thrombocytopenic purpura?

Accepted Answer

Drugs bind to platelets, forming a complex that is targeted by antibodies and complement, leading to platelet destruction.

Question 11

Which of the following autoimmune diseases is characterized by abnormal antibodies that mimic TSH, leading to excessive thyroid hormone production?

Accepted Answer

Graves' disease

Question 12

A patient presents with muscle weakness and fatigue. Laboratory tests reveal antibodies against acetylcholine receptors. What is the most likely diagnosis?

Accepted Answer

Myasthenia gravis

Question 13

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

Accepted Answer

Immune complexes of IgM and IgG deposit in joints, causing chronic inflammation

Question 14

Which of the following is a cell-mediated autoimmune disease characterized by T cell destruction of pancreatic beta cells?

Accepted Answer

Type 1 diabetes mellitus

Question 15

A patient with a history of multiple sclerosis is most likely to have which of the following underlying immunological abnormalities?

Accepted Answer

Abnormal T cells, autoantibodies, and macrophages attacking the myelin sheath in the CNS

Question 16

Which of the following best describes the difference between embryonic and adult stem cells?

Accepted Answer

Embryonic stem cells are pluripotent and can generate all cell types, while adult stem cells are multipotent and can only become a specific family of cells.

Question 17

Which of the following best explains why corneal transplants are less likely to be rejected than other organ transplants?

Accepted Answer

The cornea is a privileged site where antibodies do not normally circulate.

Question 18

A patient with psoriasis is treated with a drug that targets TNF-α. What is the rationale for this therapy?

Accepted Answer

Psoriasis is a T helper cell-mediated disease, and TNF-α is a key cytokine in the inflammatory response.

Question 19

Which of the following best describes the process of desensitization therapy for allergies?

Accepted Answer

Increasing doses of antigen are injected to stimulate IgG production, which competes with IgE for antigen binding.

Disorders of the Immune System: Hypersensitivities, Autoimmune Diseases, and Immunodeficiencies

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