Master Hypersensitivity Reactions: Types, Mechanisms, and Clinical Significance

Question 1

What is the primary pharmacological mechanism by which antihistamines alleviate allergic reactions?

Accepted Answer

Inhibition of mast cell degranulation

Answer

Prevention of IgE binding to receptors

Answer

Reduction of inflammatory response

Answer

Suppression of T cell activation

Question 2

Which mechanism is characteristic of type I hypersensitivity reactions?

Accepted Answer

Antibody-mediated activation of complement

Answer

Antibody-mediated cytotoxicity

Answer

T cell-mediated cytotoxicity

Answer

Formation of immune complexes

Question 3

Which diagnostic test is primarily used to confirm type III hypersensitivity reactions?

Accepted Answer

Complement fixation test

Answer

Skin prick test

Answer

RAST (Radioallergosorbent test)

Answer

Patch test

Question 4

Delayed-type hypersensitivity reactions primarily involve which type of immune cells?

Accepted Answer

T lymphocytes

Answer

Neutrophils

Answer

Eosinophils

Answer

Macrophages

Question 5

The skin prick test is primarily used to diagnose which type of hypersensitivity reaction?

Accepted Answer

Type I

Answer

Type II

Answer

Type III

Answer

Type IV

Question 6

The term 'atopic' refers to:

Accepted Answer

A tendency to develop IgE-mediated hypersensitivity reactions

Answer

A specific type of immune deficiency

Answer

An autoimmune disorder

Answer

A type of infectious disease

Question 7

Describe the sequential interactions between T helper cells, macrophages, and neutrophils in the development of delayed-type hypersensitivity reactions.

Accepted Answer

T helper cells activate macrophages, which release cytokines that attract neutrophils.

Answer

Neutrophils release cytokines that directly activate T helper cells.

Answer

Macrophages phagocytose antigens and present them to T helper cells, which then activate neutrophils.

Answer

T helper cells directly activate neutrophils without involving macrophages.

Question 8

Which type of hypersensitivity reaction is characterized by the formation of immune complexes that activate complement, leading to tissue damage?

Accepted Answer

Type III

Answer

Type I

Answer

Type II

Answer

Type IV

Question 9

In an immediate (Type I) hypersensitivity reaction, which immunoglobulin class is primarily responsible for triggering the release of inflammatory mediators?

Accepted Answer

IgE

Answer

IgA

Answer

IgD

Answer

IgG

Question 10

Which type of hypersensitivity reaction involves the activation of cytotoxic T cells, leading to antibody-dependent cell-mediated cytotoxicity?

Accepted Answer

Type II

Answer

Type I

Answer

Type III

Answer

Type IV

Question 11

A positive skin patch test with a specific allergen indicates which type of hypersensitivity reaction?

Accepted Answer

Type IV

Answer

Type I

Answer

Type II

Answer

Type III

Question 12

Which of the following is a common clinical manifestation of immune complex-mediated hypersensitivity reactions?

Accepted Answer

Hemolytic anemia

Answer

Anaphylaxis

Answer

Contact dermatitis

Answer

Delayed skin reaction

Question 13

In immediate (Type I) hypersensitivity reactions, which mechanism is responsible for the release of inflammatory mediators?

Accepted Answer

Degranulation of mast cells and basophils

Answer

Activation of complement

Answer

Antibody-dependent cell-mediated cytotoxicity

Answer

Formation of immune complexes

Question 14

In allergic reactions (Type I), which immune cells are primarily responsible for mediating the response?

Accepted Answer

Mast cells

Answer

Neutrophils

Answer

Macrophages

Answer

T helper cells

Question 15

Which of the following is a diagnostic test commonly used to detect delayed-type hypersensitivity reactions?

Accepted Answer

Skin patch test

Answer

Skin prick test

Answer

Intradermal skin test

Answer

Radioimmunoassay

Question 16

Which cell type plays a central role in cytotoxic (type II) hypersensitivity reactions?

Accepted Answer

Cytotoxic T lymphocytes

Answer

Macrophages

Answer

Neutrophils

Answer

Eosinophils

Question 17

Which of the following drugs is commonly used to treat acute anaphylactic reactions?

Accepted Answer

Epinephrine

Answer

Histamine-2 receptor antagonists

Answer

Beta-blockers

Answer

Montelukast

Question 18

What is the main difference between atopic and non-atopic hypersensitivity reactions?

Accepted Answer

Atopic reactions are IgE-mediated, while non-atopic reactions are IgG-mediated.

Answer

Atopic reactions are immediate, while non-atopic reactions are delayed.

Answer

Atopic reactions are more common in children, while non-atopic reactions are more common in adults.

Answer

There is no difference between atopic and non-atopic hypersensitivity reactions.

Question 19

Which cell is primarily responsible for antibody-dependent cell-mediated cytotoxicity (ADCC)?

Accepted Answer

Natural killer cell

Answer

Macrophage

Answer

Neutrophil

Answer

Eosinophil

Question 20

What is the primary mechanism by which immune complexes cause tissue damage in type III hypersensitivity?

Accepted Answer

Activation of the complement system and release of inflammatory mediators

Answer

Direct cytotoxicity

Answer

Neutrophil infiltration

Answer

Macrophage phagocytosis

Question 21

Which type of hypersensitivity reaction involves the release of cytokines such as interferon-gamma and tumor necrosis factor-alpha?

Accepted Answer

Type IV

Answer

Type I

Answer

Type II

Answer

Type III

Question 22

What is a common clinical manifestation of type I hypersensitivity reactions?

Accepted Answer

Anaphylaxis

Answer

Hemolytic anemia

Answer

Glomerulonephritis

Answer

Contact dermatitis

Question 23

Which diagnostic test is typically used to confirm type II hypersensitivity reactions?

Accepted Answer

Direct Coombs' test

Answer

Skin prick test

Answer

Radioallergosorbent test (RAST)

Answer

Patch test

Question 24

What is the role of the major histocompatibility complex (MHC) in type IV hypersensitivity reactions?

Accepted Answer

Presents antigens to T cells, initiating the cellular immune response

Answer

Binds to immunoglobulins

Answer

Activates the complement system

Answer

Mediates antibody-dependent cell-mediated cytotoxicity

Question 25

In delayed-type hypersensitivity reactions, tissue damage primarily results from:

Accepted Answer

Release of inflammatory mediators

Answer

Complement activation

Answer

Antibody-mediated cell destruction

Answer

Mast cell degranulation

Question 26

Which cytokine is essential for the differentiation of T helper cells into Th2 cells, facilitating the development of atopic hypersensitivity reactions?

Accepted Answer

Interleukin-4 (IL-4)

Answer

Interleukin-2 (IL-2)

Answer

Interferon gamma (IFN-γ)

Question 27

Which clinical manifestation is characteristic of type II hypersensitivity reactions?

Accepted Answer

Hemolytic anemia

Answer

Angioedema

Answer

Wheezing

Answer

Skin rash

Question 28

Which of the following is the characteristic hallmark of type I hypersensitivity reactions?

Accepted Answer

Rapid onset after allergen exposure (within minutes)

Answer

Delayed onset of 12-48 hours

Answer

Presence of cytotoxic antibodies

Answer

Formation of immune complexes

Question 29

In type II hypersensitivity reactions, which molecules are primarily targeted by antibodies?

Accepted Answer

Surface membrane proteins

Answer

Carbohydrate antigens

Answer

Viral antigens

Answer

Immunoglobulin molecules

Question 30

Which type of hypersensitivity reaction involves the deposition of immune complexes in tissues, potentially leading to inflammation?

Accepted Answer

Type III

Answer

Type IV

Answer

Type I

Answer

Type II

Question 31

Which cytokine is predominantly responsible for the characteristic delayed onset and inflammatory response in type IV hypersensitivity reactions?

Accepted Answer

Interferon-gamma

Answer

Interleukin-2

Answer

Tumor necrosis factor-alpha

Answer

Interleukin-4

Question 32

Which of the following is NOT a diagnostic tool for type I hypersensitivity reactions?

Accepted Answer

Complement fixation test

Answer

Measurement of specific IgE antibodies

Answer

Radioallergosorbent test (RAST)

Answer

Skin prick test

Question 33

In the context of a type III hypersensitivity reaction, what is a primary function of the complement system?

Accepted Answer

Opsonization and phagocytosis of immune complexes

Answer

Cytotoxic lysis of target cells

Answer

Antibody production

Answer

Inflammation

Question 34

Which of the following is a potential life-threatening manifestation of severe type I hypersensitivity reactions?

Accepted Answer

Anaphylaxis

Answer

Erythema nodosum

Answer

Asthma

Question 35

What distinguishes a cytotoxic antibody from other antibody classes?

Accepted Answer

Its ability to mediate target cell lysis through complement-dependent cytotoxicity

Answer

Its ability to activate phagocytes

Answer

Its ability to neutralize toxins

Question 36

Which cell type is primarily involved in mediating delayed-type hypersensitivity reactions?

Accepted Answer

T lymphocytes

Answer

Mast cells

Answer

Neutrophils

Answer

B lymphocytes

Question 37

What is a characteristic observation in a positive skin prick test, indicating a type I hypersensitivity reaction?

Accepted Answer

Formation of a raised, itchy bump (wheal) surrounded by redness (flare) at the injection site

Answer

Increased histamine levels in the blood

Answer

Presence of antibodies in the blood

Question 38

Which immunoglobulin class predominates in Type II hypersensitivity reactions?

Accepted Answer

IgG

Answer

IgM

Answer

IgA

Answer

IgE

Question 39

Type I hypersensitivity reactions are characterized by their:

Accepted Answer

Rapid onset of symptoms

Answer

Delayed onset of symptoms

Answer

Immune complex formation

Answer

Cell-mediated destruction

Question 40

Which cell type is central to Type IV hypersensitivity reactions?

Accepted Answer

T lymphocytes

Answer

Eosinophils

Answer

B lymphocytes

Answer

Neutrophils

Question 41

Skin prick tests are commonly employed to identify allergens responsible for:

Accepted Answer

Type I hypersensitivity reactions

Answer

Type IV hypersensitivity reactions

Answer

Type II hypersensitivity reactions

Answer

Type III hypersensitivity reactions

Question 42

Type III hypersensitivity reactions involve the deposition of immune complexes in:

Accepted Answer

Various tissues

Answer

Circulating blood

Answer

Gastrointestinal tract

Answer

Lymph nodes

Question 43

Histamine is primarily released by which cells during Type I hypersensitivity reactions?

Accepted Answer

Basophils and Mast cells

Answer

Neutrophils

Answer

Dendritic cells

Answer

Eosinophils

Question 44

Immunosuppressive drugs used in treating Type IV hypersensitivity reactions primarily act by:

Accepted Answer

Inhibiting T lymphocyte activation

Answer

Promoting antibody production

Answer

Suppressing mast cell degranulation

Answer

Increasing neutrophil function

Question 45

In Type II hypersensitivity reactions, the complement system plays a crucial role in:

Accepted Answer

Mediating cell lysis

Answer

Promoting inflammation

Answer

Neutralizing antibodies

Question 46

Which of the following is a hallmark of Type I hypersensitivity reactions?

Accepted Answer

Immediate onset after allergen exposure

Answer

Involvement of immune complexes

Answer

Antibody-mediated destruction of target cells

Answer

Delayed-type inflammatory response

Question 47

In Type II hypersensitivity reactions, antibodies bind to:

Accepted Answer

Cell surface antigens

Answer

MHC class I molecules

Answer

Free antigens in the bloodstream

Answer

Immune complexes

Question 48

Delayed-type hypersensitivity reactions are characterized by:

Accepted Answer

T cell-mediated inflammation

Answer

Neutrophilic infiltration

Answer

Antibody-mediated cytotoxicity

Answer

Immediate onset after allergen exposure

Question 49

Which of the following is a common clinical manifestation of Type I hypersensitivity reactions?

Accepted Answer

Anaphylaxis

Answer

Contact dermatitis

Answer

Graft rejection

Answer

Serum sickness

Question 50

The diagnostic test of choice for Type II hypersensitivity reactions is:

Accepted Answer

Direct antiglobulin test (DAT)

Answer

Skin prick test

Answer

Complement fixation assay

Answer

Western blot

Question 51

Which cytokine is primarily responsible for orchestrating the inflammatory response in Type IV hypersensitivity reactions?

Accepted Answer

Interferon-gamma

Answer

Tumor necrosis factor-alpha

Answer

Interleukin-4

Answer

Interleukin-10

Question 52

Treatment for Type III hypersensitivity reactions typically involves:

Accepted Answer

Removal of antigen-antibody complexes

Answer

Antimicrobial agents

Answer

Immunosuppressive therapy

Answer

Antihistamines