, CHAPTER LIST
Chapter 1: The Need for Self Recognition
Chapter 2: Antigens and Receptors
Chapter 3: Barriers to Infection
Chapter 4: Cells of the Innate Immune System
Chapter 5: Innate Immune Function
Chapter 6: Molecules of Adaptive Immunity
Chapter 7: Cells and Organs
Chapter 8: Generation of Immune Diversity: Lymphocyte Antigen Receptors
Chapter 9: Lymphocyte Development: B Cells and T Cells
Chapter 10: Lymphocyte Activation
Chapter 11: Lymphocyte Function
Chapter 12: Regulation of Adaptive Responses
Chapter 13: The Well Patient: How Innate and Adaptive Immune Responses
Maintain Health
Chapter 14: Hypersensitivity States
Chapter 15: Immunodeficiency
Chapter 16: Autoimmunity
Chapter 17: Transplantation
Chapter 18: Immune Pharmacotherapy
Chapter 19: Tumor Immunity
Chapter 20: Measurement of Immune Function
,Chapter 1: The Need for Self Recognition
Q1
The most fundamental immunologic consequence of failure to distinguish self from
non-self is:
A. Inability to generate immune memory
B. Development of immunodeficiency
C. Autoimmune tissue destruction
D. Failure of antigen presentation
Answer: C
Rationale:
The immune system is evolutionarily constrained to avoid attacking host tissues. Failure
of self-recognition mechanisms—particularly central and peripheral tolerance—leads to
immune activation against self antigens, resulting in autoimmune disease. Immune
memory and antigen presentation can remain intact, but tolerance failure specifically
manifests as autoimmunity.
Key words: Self-tolerance, autoimmunity, immune discrimination
Q2
Which statement best explains why immune tolerance must be established before
exposure to most pathogens?
A. Pathogens share identical antigens with host tissues
B. Self antigens are present at much higher concentrations
C. The immune system is fully activated at birth
D. Adaptive immunity lacks specificity early in life
Answer: B
,Rationale:
Self antigens are continuously present and abundant. Without early tolerance
mechanisms (e.g., thymic negative selection), lymphocytes reactive to self would be
activated immediately. Pathogen exposure occurs later and intermittently, making prior
tolerance to self essential.
Key words: Central tolerance, antigen abundance, thymic education
Q3
A mutation impairing negative selection in the thymus would most directly affect which
immune process?
A. Antibody class switching
B. Elimination of autoreactive T cells
C. Complement activation
D. Neutrophil chemotaxis
Answer: B
Rationale:
Negative selection eliminates T cells with high affinity for self-peptide–MHC complexes.
Failure of this process allows autoreactive T cells into circulation, predisposing to
autoimmunity. Other options involve peripheral immune functions unrelated to self-
recognition.
Key words: Negative selection, thymus, autoreactive T cells
Q4
Which immune cell type is most critical for initiating immune responses while
simultaneously maintaining self-tolerance?
A. Neutrophils
B. B cells
C. Dendritic cells
D. NK cells
,Answer: C
Rationale:
Dendritic cells (DCs) serve as professional antigen-presenting cells. In the absence of
danger signals, DCs present self antigens in a tolerogenic context, promoting T cell
anergy or regulatory T cell induction. Thus, they bridge immunity and tolerance.
Key words: Dendritic cells, antigen presentation, tolerogenic signaling
Q5
Immune surveillance against cancer relies on which principle established in self-
recognition?
A. Recognition of pathogen-associated molecular patterns
B. Elimination of all rapidly dividing cells
C. Detection of altered self antigens
D. Antibody-independent cytotoxicity
Answer: C
Rationale:
Tumor cells express altered self (neoantigens, abnormal MHC expression). The immune
system must tolerate normal self while recognizing deviations. Cancer immunity
therefore directly depends on refined self-recognition rather than foreign antigen
detection.
Key words: Altered self, tumor antigens, immune surveillance
Q6
Which scenario best illustrates a breakdown in peripheral tolerance?
A. Failure of V(D)J recombination
B. Absence of complement proteins
C. Loss of regulatory T cell function
D. Impaired neutrophil phagocytosis
,Answer: C
Rationale:
Peripheral tolerance mechanisms—particularly regulatory T cells (Tregs)—suppress self-
reactive lymphocytes that escape central tolerance. Loss of Treg function results in
uncontrolled activation against self tissues despite normal lymphocyte development.
Key words: Peripheral tolerance, Tregs, immune suppression
Q7
Why does the innate immune system generally not attack self tissues?
A. Innate cells undergo clonal deletion
B. Innate receptors lack specificity
C. Pattern-recognition receptors detect conserved microbial motifs
D. Innate cells are short-lived
Answer: C
Rationale:
Innate immune cells use pattern-recognition receptors (PRRs) that detect pathogen-
associated molecular patterns (PAMPs), which are absent in host cells. This evolutionary
design minimizes self-reactivity without requiring tolerance mechanisms.
Key words: Innate immunity, PRRs, PAMPs
Q8
Which clinical condition most directly demonstrates the necessity of self-tolerance?
A. Severe combined immunodeficiency
B. Systemic lupus erythematosus
C. Acute bacterial sepsis
D. Vaccine failure
Answer: B
, Rationale:
Systemic lupus erythematosus is characterized by immune responses against nuclear
self antigens, reflecting a profound failure of immune tolerance. Immunodeficiency
reflects weak immunity, not loss of self-recognition.
Key words: Autoimmune disease, SLE, loss of tolerance
Q9
Which mechanism allows the immune system to tolerate commensal microbiota while
remaining responsive to pathogens?
A. Clonal deletion of microbiota-reactive lymphocytes
B. Physical separation and controlled immune exposure
C. Absence of innate immune receptors in the gut
D. Permanent immune anergy
Answer: B
Rationale:
Mucosal barriers, regulatory cytokines, and compartmentalized immune responses allow
controlled exposure to commensals. This preserves tolerance while enabling rapid
response to invasive pathogens.
Key words: Mucosal immunity, commensals, immune compartmentalization
Q10
Which principle best explains why transplant rejection occurs despite sterile surgical
conditions?
A. Transplanted tissues express pathogen antigens
B. Grafts activate innate immunity nonspecifically
C. Donor tissues are recognized as non-self
D. Immunosuppressive drugs are insufficient
Answer: C
Chapter 1: The Need for Self Recognition
Chapter 2: Antigens and Receptors
Chapter 3: Barriers to Infection
Chapter 4: Cells of the Innate Immune System
Chapter 5: Innate Immune Function
Chapter 6: Molecules of Adaptive Immunity
Chapter 7: Cells and Organs
Chapter 8: Generation of Immune Diversity: Lymphocyte Antigen Receptors
Chapter 9: Lymphocyte Development: B Cells and T Cells
Chapter 10: Lymphocyte Activation
Chapter 11: Lymphocyte Function
Chapter 12: Regulation of Adaptive Responses
Chapter 13: The Well Patient: How Innate and Adaptive Immune Responses
Maintain Health
Chapter 14: Hypersensitivity States
Chapter 15: Immunodeficiency
Chapter 16: Autoimmunity
Chapter 17: Transplantation
Chapter 18: Immune Pharmacotherapy
Chapter 19: Tumor Immunity
Chapter 20: Measurement of Immune Function
,Chapter 1: The Need for Self Recognition
Q1
The most fundamental immunologic consequence of failure to distinguish self from
non-self is:
A. Inability to generate immune memory
B. Development of immunodeficiency
C. Autoimmune tissue destruction
D. Failure of antigen presentation
Answer: C
Rationale:
The immune system is evolutionarily constrained to avoid attacking host tissues. Failure
of self-recognition mechanisms—particularly central and peripheral tolerance—leads to
immune activation against self antigens, resulting in autoimmune disease. Immune
memory and antigen presentation can remain intact, but tolerance failure specifically
manifests as autoimmunity.
Key words: Self-tolerance, autoimmunity, immune discrimination
Q2
Which statement best explains why immune tolerance must be established before
exposure to most pathogens?
A. Pathogens share identical antigens with host tissues
B. Self antigens are present at much higher concentrations
C. The immune system is fully activated at birth
D. Adaptive immunity lacks specificity early in life
Answer: B
,Rationale:
Self antigens are continuously present and abundant. Without early tolerance
mechanisms (e.g., thymic negative selection), lymphocytes reactive to self would be
activated immediately. Pathogen exposure occurs later and intermittently, making prior
tolerance to self essential.
Key words: Central tolerance, antigen abundance, thymic education
Q3
A mutation impairing negative selection in the thymus would most directly affect which
immune process?
A. Antibody class switching
B. Elimination of autoreactive T cells
C. Complement activation
D. Neutrophil chemotaxis
Answer: B
Rationale:
Negative selection eliminates T cells with high affinity for self-peptide–MHC complexes.
Failure of this process allows autoreactive T cells into circulation, predisposing to
autoimmunity. Other options involve peripheral immune functions unrelated to self-
recognition.
Key words: Negative selection, thymus, autoreactive T cells
Q4
Which immune cell type is most critical for initiating immune responses while
simultaneously maintaining self-tolerance?
A. Neutrophils
B. B cells
C. Dendritic cells
D. NK cells
,Answer: C
Rationale:
Dendritic cells (DCs) serve as professional antigen-presenting cells. In the absence of
danger signals, DCs present self antigens in a tolerogenic context, promoting T cell
anergy or regulatory T cell induction. Thus, they bridge immunity and tolerance.
Key words: Dendritic cells, antigen presentation, tolerogenic signaling
Q5
Immune surveillance against cancer relies on which principle established in self-
recognition?
A. Recognition of pathogen-associated molecular patterns
B. Elimination of all rapidly dividing cells
C. Detection of altered self antigens
D. Antibody-independent cytotoxicity
Answer: C
Rationale:
Tumor cells express altered self (neoantigens, abnormal MHC expression). The immune
system must tolerate normal self while recognizing deviations. Cancer immunity
therefore directly depends on refined self-recognition rather than foreign antigen
detection.
Key words: Altered self, tumor antigens, immune surveillance
Q6
Which scenario best illustrates a breakdown in peripheral tolerance?
A. Failure of V(D)J recombination
B. Absence of complement proteins
C. Loss of regulatory T cell function
D. Impaired neutrophil phagocytosis
,Answer: C
Rationale:
Peripheral tolerance mechanisms—particularly regulatory T cells (Tregs)—suppress self-
reactive lymphocytes that escape central tolerance. Loss of Treg function results in
uncontrolled activation against self tissues despite normal lymphocyte development.
Key words: Peripheral tolerance, Tregs, immune suppression
Q7
Why does the innate immune system generally not attack self tissues?
A. Innate cells undergo clonal deletion
B. Innate receptors lack specificity
C. Pattern-recognition receptors detect conserved microbial motifs
D. Innate cells are short-lived
Answer: C
Rationale:
Innate immune cells use pattern-recognition receptors (PRRs) that detect pathogen-
associated molecular patterns (PAMPs), which are absent in host cells. This evolutionary
design minimizes self-reactivity without requiring tolerance mechanisms.
Key words: Innate immunity, PRRs, PAMPs
Q8
Which clinical condition most directly demonstrates the necessity of self-tolerance?
A. Severe combined immunodeficiency
B. Systemic lupus erythematosus
C. Acute bacterial sepsis
D. Vaccine failure
Answer: B
, Rationale:
Systemic lupus erythematosus is characterized by immune responses against nuclear
self antigens, reflecting a profound failure of immune tolerance. Immunodeficiency
reflects weak immunity, not loss of self-recognition.
Key words: Autoimmune disease, SLE, loss of tolerance
Q9
Which mechanism allows the immune system to tolerate commensal microbiota while
remaining responsive to pathogens?
A. Clonal deletion of microbiota-reactive lymphocytes
B. Physical separation and controlled immune exposure
C. Absence of innate immune receptors in the gut
D. Permanent immune anergy
Answer: B
Rationale:
Mucosal barriers, regulatory cytokines, and compartmentalized immune responses allow
controlled exposure to commensals. This preserves tolerance while enabling rapid
response to invasive pathogens.
Key words: Mucosal immunity, commensals, immune compartmentalization
Q10
Which principle best explains why transplant rejection occurs despite sterile surgical
conditions?
A. Transplanted tissues express pathogen antigens
B. Grafts activate innate immunity nonspecifically
C. Donor tissues are recognized as non-self
D. Immunosuppressive drugs are insufficient
Answer: C
