Which of the following are the two main keys to immune system
function?
A) Memory and tolerance
B) Recognition and
response
C) Specificity and diversity
D) Activation and suppression
B) Recognition and response
Primary lymphoid tissues are:
A) Sites where mature lymphocytes
encounter antigens
B) Sites of development and maturation of
lymphoid cells
C) Only the spleen and lymph nodes
D)
Involved in antigen presentation to T cells
B) Sites of development and maturation of lymphoid cells
Which of the following activates the classical complement
pathway?
A) Lipopolysaccharides (LPS)
B) Mannose-binding
lectin
C) IgG and IgM antibodies
D) Cytokines
C) IgG and IgM antibodies
Which of the following is a characteristic of innate immunity?
A) Highly specific response to antigens
B) Generates memory
after first exposure
C) Fast response but less specific
D)
Receptors are generated through gene segment recombination
C) Fast response but less specific
Which of the following cells are of myeloid origin and generally part
of the innate immune system?
A) B cells and T cells
B) NK
cells and dendritic cells
C) Macrophages and neutrophils
D) Plasma cells and cytotoxic T cells
C) Macrophages and neutrophils
MHC class II molecules present:
A) Endogenous antigens to CD8+
T cells
B) Exogenous antigens to CD4+ T cells
C)
Self-antigens to NK cells
D) Lipid antigens to B cells
B) Exogenous antigens to CD4+ T cells
Which of the following is not an outcome of
complement activation?
A) Opsonization
B)
Inflammation
C) Lysis
D) Antibody hypermutation
D) Antibody hypermutation
Germ-line encoded receptors are characteristic of:
A) Adaptive
immunity
B) Innate immunity
C) Memory B cells
D)
Somatic hypermutation
B) Innate immunity
Which cytokine is pro-inflammatory?
A) IL-10
B)
TGF-β
C) IL-1β
D) IL-4
C) IL-1β
Which of the following is an effector function of antibodies?
A) Rolling
B) Opsonization
C) Diapedesis
D) T cell licensing
B) Opsonization
Briefly distinguish between primary and secondary lymphoid tissues and provide an example of each.
Primary: site of lymphocyte development/maturation
(ex: bone marrow, thymus).
Secondary: site
where mature lymphocytes encounter antigen (ex: spleen, lymph nodes).
list the three major functions of the innate immune system.
Physical/chemical barriers, cellular response to infection, activation of adaptive immunity.
Define an epitope and explain the difference between a sequential epitope and a conformational epitope.
Epitope: antigen region recognized by antibody or T
cell.
Sequential: linear amino acid
sequence.
Conformational: non-linear amino
acids brought together by 3D folding.
What are the four stages of leukocyte trafficking?
Rolling → Activation → Firm adhesion → Diapedesis.
List the three signals in the three-signal hypothesis for T cell activation and the molecules involved in each.
Signal 1: TCR-MHC/peptide interaction.
Signal 2: Costimulation (CD28-CD80/86).
Signal 3: Cytokine signaling (cytokine binds
receptor on T cell)
What is meant by MHC restriction?
T cells can only recognize antigens presented on self MHC molecules.
Explain the role of RAG1/2 in B and T cell receptor development.
- RAG1/2 recombines gene segments (VDJ recombination) to generate diverse B/T cell receptors.
Distinguish between monoclonal and polyclonal antibodies.
Monoclonal: single epitope specificity.
Polyclonal: multiple epitopes on same antigen.
A patient presents with a bacterial infection. Explain how the innate immune system recognizes the pathogen and initiates a response, including complement activation.
Innate immune cells recognize PAMPs via PRRs, trigger phagocytosis, release cytokines, and activate complement (opsonization, inflammation, lysis).
During a secondary infection, why does the adaptive immune response increase compared to the primary response, whereas the innate immune response remains the same?
Adaptive immunity has memory cells → faster, stronger response. Innate immunity has no memory → response similar each time.
A researcher is designing a monoclonal antibody to target a specific epitope on a viral protein. Explain why a monoclonal antibody is preferred over a polyclonal antibody for this application.
Monoclonal antibody targets a single epitope → precise, reproducible, less off-target effects.
Explain the process by which a dendritic cell activates a naive cytotoxic CD8⁺ T cell, including the role of cross-presentation.
DC processes antigens → presents on MHC I (endogenous) or via cross-presentation → TCR recognizes antigen-MHC I → co-stimulation + cytokines → CD8⁺ differentiation into CTLs.
A patient has a mutation preventing proper function of CD28 on T cells. Predict the impact on T cell activation according to the three-signal hypothesis.
Without CD28, costimulatory signal missing → T cells cannot fully activate → impaired adaptive response.
Describe how a checkpoint inhibitor like ipilimumab enhances T cell responses in cancer therapy.
Ipilimumab blocks CTLA-4 → prevents inhibition of CD28 → T cells remain active → enhanced anti-tumor immunity.
Which antibody effector function causes pathogens to clump together, making them easier to clear?
A. Neutralization
B. Agglutination
C. ADCC
D. Degranulation
B. Agglutination
Which function describes antibodies coating a pathogen to enhance phagocytosis?
A. Complement fixation
B. Opsonization
C.
Neutralization
D. Agglutination
B. Opsonization
Which effector function prevents viruses and toxins from binding to host cells?
A. Neutralization
B. ADCC
C. Opsonization
D.
Complement fixation
A. Neutralization
Which antibody isotype is most effective at initiating the classical complement pathway?
A. IgA
B. IgE
C. IgM
D. IgD
C. IgM
Which process requires NK cells binding to the Fc region of IgG-coated target cells?
A. Opsonization
B. Complement fixation
C. ADCC
D. Neutralization
C. ADCC
Which effector function is triggered when IgE on mast cells becomes cross-linked by an allergen?
A. Neutralization
B. Degranulation
C.
Agglutination
D. Complement fixation
B. Degranulation
Which antibody function leads to the formation of the membrane attack complex (MAC)?
A. Opsonization
B. Complement fixation
C.
Neutralization
D. ADCC
B. Complement fixation
Which antibody function is MOST directly associated with protection against helminths (parasites)?
A. ADCC
B. Degranulation via IgE
C. Neutralization
D. Agglutination
B. Degranulation via IgE
Which antibody function enhances pathogen clearance specifically by facilitating ingestion by macrophages and neutrophils?
A. Neutralization
B. Opsonization
C. ADCC
D. Degranulation
B. Opsonization
Which function of antibodies does not require phagocytic cells?
A. Opsonization
B. Agglutination
C. Neutralization
D. ADCC
C. Neutralization
Which statement best distinguishes a monoclonal antibody from a polyclonal antibody?
A. Monoclonal antibodies bind multiple epitopes, while polyclonal
antibodies bind only one epitope.
B. Monoclonal antibodies come
from multiple B-cell clones, while polyclonal antibodies come from a
single B-cell clone.
C. Monoclonal antibodies recognize a single
epitope, while polyclonal antibodies recognize many epitopes on the
same antigen.
D. Polyclonal antibodies are produced only in
vitro, while monoclonal antibodies are produced only in vivo.
C. Monoclonal antibodies recognize a single epitope, while polyclonal antibodies recognize many epitopes on the same antigen.
Polyclonal antibodies are best described as:
A. Identical antibodies produced in hybridoma culture.
B. A
mixture of antibodies produced by several B-cell clones against
different epitopes.
C. Engineered antibodies with reduced
immunogenicity.
D. Antibodies that bind only intracellular proteins.
B. A mixture of antibodies produced by several B-cell clones against different epitopes.
The endogenous antigen pathway results in antigen presentation on which molecule?
A. MHC I
B. MHC II
C. CD40
D. BCR
A. MHC I
Which type of antigen is processed through the endogenous pathway?
A. Extracellular bacteria
B. Environmental allergens
C.
Intracellular proteins such as viral antigens
D. Helminths
C. Intracellular proteins such as viral antigens
Cross-presentation allows dendritic cells to:
A. Present endogenous antigens on MHC II only.
B. Present
exogenous antigens on MHC I to activate CD8⁺ T cells.
C. Produce
antibodies against multiple epitopes.
D. Present lipid antigens
through CD1.
B. Present exogenous antigens on MHC I to activate CD8⁺ T cells
Activation of naïve CD8⁺ T cells requires antigen presented on:
A. MHC II
B. CD40
C. MHC I
D. TLR4
C. MHC I
Which of the following provides the co-stimulatory signal required for T-cell activation?
A. TCR binding to antigen
B. CD40 binding to CD40L
C. B7
on dendritic cells binding to CD28 on T cells
D. IL-12 secretion
C. B7 on dendritic cells binding to CD28 on T cells
Which cytokine produced by dendritic cells is essential for CD8⁺ T-cell activation and differentiation into CTLs?
A. IL-4
B. IL-12
C. IL-10
D. IL-17
B. IL-12
Which interaction is responsible for “licensing” dendritic cells, enhancing their ability to activate CD8⁺ T cells?
A. B7–CD28
B. CD40–CD40L
C. TCR–MHC II
D.
IL-12–IL-12 receptor
B. CD40–CD40L
Presentation of exogenous antigens to naïve CD4⁺ T cells primarily occurs through:
A. MHC I
B. MHC II
C. Fc receptors
D. Complement receptors
B. MHC II
What is the primary function of a checkpoint inhibitor in cancer immunotherapy?
A. To suppress T-cell activation
B. To inhibit molecules that
normally inhibit T-cell activation
C. To activate B cells to
produce more antibodies
D. To block antigen presentation on
dendritic cells
B. To inhibit molecules that normally inhibit T-cell activation
Which T-cell molecule is targeted by the checkpoint inhibitor ipilimumab?
A. CD28
B. PD-1
C. CTLA-4
D. CD40L
C. CTLA-4
CTLA-4 normally functions by:
A. Enhancing T-cell co-stimulation
B. Blocking CD28 from
binding to CD80/86
C. Increasing cytokine secretion
D.
Presenting antigen to T cells
B. Blocking CD28 from binding to CD80/86
Which statement best describes the mechanism of checkpoint inhibition?
A. It increases inhibitory signaling to prevent autoimmunity.
B. It blocks inhibitory receptors, removing the “brake” on T-cell
activation.
C. It prevents T cells from binding to APCs.
D. It replaces MHC molecules on dendritic cells.
B. It blocks inhibitory receptors, removing the “brake” on T-cell activation.
When CTLA-4 is active on a T cell, what is the result?
A. Enhanced co-stimulation through CD28
B. Strong activation
of cytotoxic T lymphocytes
C. Suppressed T-cell activation
D. Increased antibody production
C. Suppressed T-cell activation
Ipilimumab enhances antitumor immunity by:
A. Blocking PD-L1
B. Blocking CTLA-4 so CD28 can bind
CD80/86
C. Inhibiting dendritic cell maturation
D.
Stimulating IL-10 production
B. Blocking CTLA-4 so CD28 can bind CD80/86
Which of the following is a myeloid cell that functions primarily in the innate immune response?
A. B cell
B. T cell
C. Neutrophil
D. NK cell
C. Neutrophil6
Which cell type is of lymphoid origin but functions in the innate immune system?
A. NK cell
B. Basophil
C. Macrophage
D. Dendritic cell
A. NK cell
B cells are classified as:
A. Myeloid, innate
B. Lymphoid, innate
C. Myeloid,
adaptive
D. Lymphoid, adaptive
D. Lymphoid, adaptive
Which immune cell is of myeloid origin and responsible for allergic inflammation?
A. Basophil
B. NK cell
C. T cell
D. B cell
A. Basophil
Which cell is myeloid-derived, part of the innate system, and acts as a key phagocyte?
A. T cell
B. B cell
C. Macrophage
D. NK cell
C. Macrophage
Dendritic cells are best described as:
A. Myeloid, innate cells that also activate adaptive immunity
B. Lymphoid, innate cells that produce antibodies
C. Myeloid,
adaptive cells that kill viruses
D. Lymphoid, adaptive cells
that phagocytose bacteria
A. Myeloid, innate cells that also activate adaptive immunity
Which of the following is lymphoid-derived and functions in the adaptive immune system?
A. Basophil
B. NK cell
C. Neutrophil
D. T cell
D. T cell
Which of the following activates the classical complement pathway?
A. IgG and IgM antibodies bound to antigen
B. Mannose-binding
lectin binding to pathogen surfaces
C. Spontaneous hydrolysis of
C3
D. NK cells
A. IgG and IgM antibodies bound to antigen
The alternative complement pathway is primarily activated by:
A. IgA antibodies
B. PAMPs such as LPS and spontaneous
hydrolysis of C3
C. Mannose-binding lectin
D. T-cell
receptor signaling
B. PAMPs such as LPS and spontaneous hydrolysis of C3
The mannose-binding lectin (MBL) pathway is triggered when:
A. Antibodies bind to antigen
B. MBL binds to mannose residues
on microbial surfaces
C. C3 spontaneously hydrolyzes on host
cells
D. Complement receptor 1 (CR1) is engaged
B. MBL binds to mannose residues on microbial surfaces
Which statement about the alternative complement pathway is true?
A. It requires prior antibody binding to activate
B.
Spontaneous C3 hydrolysis occurs, but full activation only happens on
non-self surfaces
C. It is initiated by mannose residues on
pathogens
D. It exclusively targets self-cells for clearance
B. Spontaneous C3 hydrolysis occurs, but full activation only happens on non-self surfaces
According to clonal selection theory, what occurs after a B or T cell receptor binds its specific antigen?
A. Immediate apoptosis
B. Clonal expansion of the activated
lymphocyte
C. Differentiation into NK cells
D. Secretion
of complement proteins
B. Clonal expansion of the activated lymphocyte
One major tenet of clonal selection theory is:
A. All B and T cells are pre-activated at birth
B. Individual
B and T cell receptors are generated by gene segment
rearrangement
C. Antigen recognition is unnecessary for
lymphocyte activation
D. Only macrophages undergo clonal expansion
B. Individual B and T cell receptors are generated by gene segment rearrangement
Clonal selection theory predicts that:
A. Lymphocytes with receptors that do not bind antigen are
eliminated or remain inactive
B. All lymphocytes are
identical
C. Activation of T cells does not require receptor
engagement
D. Antibodies are produced before antigen exposure
A. Lymphocytes with receptors that do not bind antigen are eliminated or remain inactive