PCB 3233 Exam 4 V1 | PCB 3233
Immunology | Actual Q&A with Rationale
(PCB3233 Exam 4) | University of Central
Florida
1. During T-cell development, which process ensures that
1. Which cytokine is primarily responsible for inducing the isotype switch to IgE in B cells
during a Type I hypersensitivity response?
A. IL-4
B. IL-2
C. IFN-gamma
D. IL-10
Answer: A
Rationale: Interleukin-4 (IL-4) is secreted by Th2 cells and plays a critical role in directing
B cells to undergo class switch recombination to IgE. This process is essential for the
sensitization phase of allergic reactions where IgE binds to mast cells. In contrast, IFN-
gamma typically promotes a switch to IgG classes that are more involved in opsonization
and complement fixation.
2. The mechanism of Type II hypersensitivity involves which of the following?
A. T-cell mediated cytotoxicity
,B. Antibody-dependent cell-mediated cytotoxicity (ADCC) or complement-mediated lysis
C. Immune complex deposition in tissues
D. IgE-mediated mast cell degranulation
Answer: B
Rationale: Type II hypersensitivity is characterized by antibodies (IgG or IgM) binding to
antigens on the surface of specific cells or tissues. This binding leads to cell destruction
through the activation of the complement system or via ADCC by NK cells and
macrophages. This mechanism is distinct from Type III, which involves soluble complexes,
and Type IV, which is cell-mediated.
3. A patient experiencing a systemic reaction to a bee sting is undergoing which type of
hypersensitivity?
A. Type II Hypersensitivity
B. Type I Hypersensitivity
C. Type III Hypersensitivity
D. Type IV Hypersensitivity
Answer: B
Rationale: Systemic anaphylaxis following a bee sting is a classic example of Type I
hypersensitivity, also known as immediate hypersensitivity. This reaction occurs when an
allergen cross-links IgE antibodies already bound to Fc receptors on mast cells, causing the
, release of vasoactive amines. The rapid onset of symptoms like hypotension and airway
constriction requires immediate medical intervention with epinephrine.
4. Which of the following conditions is an example of Type III hypersensitivity?
A. Systemic Lupus Erythematosus (SLE)
B. Poison ivy dermatitis
C. Graves’ disease
D. Erythroblastosis fetalis
Answer: A
Rationale: Systemic Lupus Erythematosus is a prototypical Type III hypersensitivity
disorder where soluble immune complexes (antigen-antibody pairs) circulate and deposit
in various tissues like the kidneys and joints. These deposits trigger the complement
cascade and attract neutrophils, leading to significant local inflammation and tissue
damage. Unlike Type II, the antigens in Type III are initially soluble rather than fixed to a
cell surface.
5. What is the primary role of the AIRE (Autoimmune Regulator) protein in the thymus?
A. It promotes the survival of all double-positive thymocytes.
B. It induces the differentiation of Th17 cells.
C. It acts as a co-stimulatory molecule for T cell activation.
D. It facilitates the expression of tissue-specific antigens for negative selection.
Immunology | Actual Q&A with Rationale
(PCB3233 Exam 4) | University of Central
Florida
1. During T-cell development, which process ensures that
1. Which cytokine is primarily responsible for inducing the isotype switch to IgE in B cells
during a Type I hypersensitivity response?
A. IL-4
B. IL-2
C. IFN-gamma
D. IL-10
Answer: A
Rationale: Interleukin-4 (IL-4) is secreted by Th2 cells and plays a critical role in directing
B cells to undergo class switch recombination to IgE. This process is essential for the
sensitization phase of allergic reactions where IgE binds to mast cells. In contrast, IFN-
gamma typically promotes a switch to IgG classes that are more involved in opsonization
and complement fixation.
2. The mechanism of Type II hypersensitivity involves which of the following?
A. T-cell mediated cytotoxicity
,B. Antibody-dependent cell-mediated cytotoxicity (ADCC) or complement-mediated lysis
C. Immune complex deposition in tissues
D. IgE-mediated mast cell degranulation
Answer: B
Rationale: Type II hypersensitivity is characterized by antibodies (IgG or IgM) binding to
antigens on the surface of specific cells or tissues. This binding leads to cell destruction
through the activation of the complement system or via ADCC by NK cells and
macrophages. This mechanism is distinct from Type III, which involves soluble complexes,
and Type IV, which is cell-mediated.
3. A patient experiencing a systemic reaction to a bee sting is undergoing which type of
hypersensitivity?
A. Type II Hypersensitivity
B. Type I Hypersensitivity
C. Type III Hypersensitivity
D. Type IV Hypersensitivity
Answer: B
Rationale: Systemic anaphylaxis following a bee sting is a classic example of Type I
hypersensitivity, also known as immediate hypersensitivity. This reaction occurs when an
allergen cross-links IgE antibodies already bound to Fc receptors on mast cells, causing the
, release of vasoactive amines. The rapid onset of symptoms like hypotension and airway
constriction requires immediate medical intervention with epinephrine.
4. Which of the following conditions is an example of Type III hypersensitivity?
A. Systemic Lupus Erythematosus (SLE)
B. Poison ivy dermatitis
C. Graves’ disease
D. Erythroblastosis fetalis
Answer: A
Rationale: Systemic Lupus Erythematosus is a prototypical Type III hypersensitivity
disorder where soluble immune complexes (antigen-antibody pairs) circulate and deposit
in various tissues like the kidneys and joints. These deposits trigger the complement
cascade and attract neutrophils, leading to significant local inflammation and tissue
damage. Unlike Type II, the antigens in Type III are initially soluble rather than fixed to a
cell surface.
5. What is the primary role of the AIRE (Autoimmune Regulator) protein in the thymus?
A. It promotes the survival of all double-positive thymocytes.
B. It induces the differentiation of Th17 cells.
C. It acts as a co-stimulatory molecule for T cell activation.
D. It facilitates the expression of tissue-specific antigens for negative selection.
