Advanced Pathophysiology UTMB 5355
EXAM 2 Module 3 Immune System Questions
With Complete Solutions
Course
UTMB
1. What is the primary function of the innate immune system?
Answer: To provide immediate, non-specific defense against pathogens.
Explanation: The innate immune system acts as the first line of defense, including
barriers (skin, mucosa), phagocytes, natural killer cells, and the complement system.
2. How do B cells contribute to adaptive immunity?
Answer: By producing antibodies that target specific antigens.
Explanation: B cells differentiate into plasma cells that secrete antibodies, which help
neutralize pathogens and mark them for destruction.
3. What is the role of helper T cells (CD4+)?
Answer: To activate B cells, cytotoxic T cells, and macrophages.
Explanation: Helper T cells recognize antigens presented by MHC class II molecules
and release cytokines to enhance immune responses.
4. How does the complement system enhance immune function?
Answer: By promoting opsonization, inflammation, and direct lysis of pathogens.
Explanation: The complement cascade enhances phagocytosis, attracts immune cells,
and forms the membrane attack complex (MAC) to destroy microbes.
5. What is the primary difference between Type I and Type IV hypersensitivity reactions?
Answer: Type I hypersensitivity is immediate and mediated by IgE, while Type IV is
delayed and mediated by T cells.
Explanation: Type I hypersensitivity (e.g., anaphylaxis) involves mast cell
degranulation, whereas Type IV (e.g., contact dermatitis) involves T-cell activation over
24-48 hours.
,6. How does autoimmune disease develop?
Answer: When the immune system mistakenly attacks self-antigens due to a loss of self-
tolerance.
Explanation: Autoimmune diseases (e.g., lupus, rheumatoid arthritis) occur due to
genetic, environmental, and immune regulatory factors that cause self-reactive immune
cells to persist.
7. What is the role of regulatory T cells (Tregs) in immune tolerance?
Answer: To suppress excessive immune responses and prevent autoimmunity.
Explanation: Tregs release anti-inflammatory cytokines (e.g., IL-10, TGF-β) that inhibit
immune activation against self-antigens.
8. How does human immunodeficiency virus (HIV) impair the immune system?
Answer: By destroying CD4+ T cells, leading to immunosuppression.
Explanation: HIV infects and depletes helper T cells, weakening both cellular and
humoral immunity, making individuals susceptible to opportunistic infections.
9. What is the significance of antigen-presenting cells (APCs) in immune activation?
Answer: APCs process and present antigens to T cells, initiating adaptive immunity.
Explanation: Dendritic cells, macrophages, and B cells present antigens via MHC
molecules to activate T cells and trigger immune responses.
10. What is the difference between passive and active immunity?
Answer: Passive immunity is acquired through external antibodies, while active
immunity is generated by the host’s immune response.
Explanation: Passive immunity (e.g., maternal antibodies, immunoglobulin therapy)
provides temporary protection, while active immunity (e.g., vaccination, infection) results
in long-term immune memory.
11. What is the difference between primary and secondary immune response?
, Answer: The primary immune response occurs upon first exposure to an antigen, while
the secondary response is faster and stronger due to memory cells.
Explanation: The primary response (e.g., after initial vaccination) is slower because
naïve B and T cells need to be activated, whereas the secondary response (e.g., after a
booster shot) is rapid and robust due to memory B and T cells.
12. How do cytotoxic T cells (CD8+) destroy infected cells?
Answer: By releasing perforin and granzymes that induce apoptosis in infected cells.
Explanation: Cytotoxic T cells recognize infected or cancerous cells via MHC class I
molecules and trigger programmed cell death.
13. What is the significance of cytokines in immune regulation?
Answer: Cytokines are signaling molecules that regulate immune cell activation,
inflammation, and communication.
Explanation: Examples include interleukins (IL-2 for T cell proliferation), interferons
(IFN-γ for antiviral defense), and tumor necrosis factors (TNF-α for inflammation).
14. What is the role of natural killer (NK) cells in immunity?
Answer: To destroy virus-infected and cancerous cells without prior antigen exposure.
Explanation: NK cells use perforin and granzyme pathways to induce apoptosis in
abnormal cells, especially those lacking MHC I expression.
15. What is immunological memory and why is it important?
Answer: It is the ability of the adaptive immune system to respond more effectively upon
re-exposure to the same antigen.
Explanation: Memory B and T cells provide long-term protection against infections,
making vaccinations effective.
16. What is the difference between central and peripheral tolerance?
, Answer: Central tolerance occurs in the thymus and bone marrow, while peripheral
tolerance occurs in secondary lymphoid organs.
Explanation: Central tolerance eliminates self-reactive immune cells during
development, while peripheral tolerance prevents mature lymphocytes from attacking
self-antigens.
17. What is the function of major histocompatibility complex (MHC) molecules?
Answer: To present antigenic peptides to T cells for immune recognition.
Explanation: MHC I presents to CD8+ T cells (cytotoxic), while MHC II presents to
CD4+ T cells (helper).
18. What are the hallmarks of chronic inflammation?
Answer: Persistent immune activation, tissue damage, and fibrosis.
Explanation: Chronic inflammation (e.g., in rheumatoid arthritis, Crohn’s disease) leads
to prolonged cytokine release and immune cell infiltration, causing tissue destruction.
19. How do mast cells contribute to allergic reactions?
Answer: By releasing histamine and other inflammatory mediators upon IgE activation.
Explanation: Mast cell degranulation in response to allergens leads to symptoms such as
swelling, itching, and anaphylaxis.
20. What is the function of dendritic cells in immunity?
Answer: To capture, process, and present antigens to T cells.
Explanation: Dendritic cells act as professional antigen-presenting cells (APCs) that
initiate adaptive immune responses.
21. What is immune surveillance?
Answer: The ability of the immune system to detect and eliminate cancerous or infected
cells.
EXAM 2 Module 3 Immune System Questions
With Complete Solutions
Course
UTMB
1. What is the primary function of the innate immune system?
Answer: To provide immediate, non-specific defense against pathogens.
Explanation: The innate immune system acts as the first line of defense, including
barriers (skin, mucosa), phagocytes, natural killer cells, and the complement system.
2. How do B cells contribute to adaptive immunity?
Answer: By producing antibodies that target specific antigens.
Explanation: B cells differentiate into plasma cells that secrete antibodies, which help
neutralize pathogens and mark them for destruction.
3. What is the role of helper T cells (CD4+)?
Answer: To activate B cells, cytotoxic T cells, and macrophages.
Explanation: Helper T cells recognize antigens presented by MHC class II molecules
and release cytokines to enhance immune responses.
4. How does the complement system enhance immune function?
Answer: By promoting opsonization, inflammation, and direct lysis of pathogens.
Explanation: The complement cascade enhances phagocytosis, attracts immune cells,
and forms the membrane attack complex (MAC) to destroy microbes.
5. What is the primary difference between Type I and Type IV hypersensitivity reactions?
Answer: Type I hypersensitivity is immediate and mediated by IgE, while Type IV is
delayed and mediated by T cells.
Explanation: Type I hypersensitivity (e.g., anaphylaxis) involves mast cell
degranulation, whereas Type IV (e.g., contact dermatitis) involves T-cell activation over
24-48 hours.
,6. How does autoimmune disease develop?
Answer: When the immune system mistakenly attacks self-antigens due to a loss of self-
tolerance.
Explanation: Autoimmune diseases (e.g., lupus, rheumatoid arthritis) occur due to
genetic, environmental, and immune regulatory factors that cause self-reactive immune
cells to persist.
7. What is the role of regulatory T cells (Tregs) in immune tolerance?
Answer: To suppress excessive immune responses and prevent autoimmunity.
Explanation: Tregs release anti-inflammatory cytokines (e.g., IL-10, TGF-β) that inhibit
immune activation against self-antigens.
8. How does human immunodeficiency virus (HIV) impair the immune system?
Answer: By destroying CD4+ T cells, leading to immunosuppression.
Explanation: HIV infects and depletes helper T cells, weakening both cellular and
humoral immunity, making individuals susceptible to opportunistic infections.
9. What is the significance of antigen-presenting cells (APCs) in immune activation?
Answer: APCs process and present antigens to T cells, initiating adaptive immunity.
Explanation: Dendritic cells, macrophages, and B cells present antigens via MHC
molecules to activate T cells and trigger immune responses.
10. What is the difference between passive and active immunity?
Answer: Passive immunity is acquired through external antibodies, while active
immunity is generated by the host’s immune response.
Explanation: Passive immunity (e.g., maternal antibodies, immunoglobulin therapy)
provides temporary protection, while active immunity (e.g., vaccination, infection) results
in long-term immune memory.
11. What is the difference between primary and secondary immune response?
, Answer: The primary immune response occurs upon first exposure to an antigen, while
the secondary response is faster and stronger due to memory cells.
Explanation: The primary response (e.g., after initial vaccination) is slower because
naïve B and T cells need to be activated, whereas the secondary response (e.g., after a
booster shot) is rapid and robust due to memory B and T cells.
12. How do cytotoxic T cells (CD8+) destroy infected cells?
Answer: By releasing perforin and granzymes that induce apoptosis in infected cells.
Explanation: Cytotoxic T cells recognize infected or cancerous cells via MHC class I
molecules and trigger programmed cell death.
13. What is the significance of cytokines in immune regulation?
Answer: Cytokines are signaling molecules that regulate immune cell activation,
inflammation, and communication.
Explanation: Examples include interleukins (IL-2 for T cell proliferation), interferons
(IFN-γ for antiviral defense), and tumor necrosis factors (TNF-α for inflammation).
14. What is the role of natural killer (NK) cells in immunity?
Answer: To destroy virus-infected and cancerous cells without prior antigen exposure.
Explanation: NK cells use perforin and granzyme pathways to induce apoptosis in
abnormal cells, especially those lacking MHC I expression.
15. What is immunological memory and why is it important?
Answer: It is the ability of the adaptive immune system to respond more effectively upon
re-exposure to the same antigen.
Explanation: Memory B and T cells provide long-term protection against infections,
making vaccinations effective.
16. What is the difference between central and peripheral tolerance?
, Answer: Central tolerance occurs in the thymus and bone marrow, while peripheral
tolerance occurs in secondary lymphoid organs.
Explanation: Central tolerance eliminates self-reactive immune cells during
development, while peripheral tolerance prevents mature lymphocytes from attacking
self-antigens.
17. What is the function of major histocompatibility complex (MHC) molecules?
Answer: To present antigenic peptides to T cells for immune recognition.
Explanation: MHC I presents to CD8+ T cells (cytotoxic), while MHC II presents to
CD4+ T cells (helper).
18. What are the hallmarks of chronic inflammation?
Answer: Persistent immune activation, tissue damage, and fibrosis.
Explanation: Chronic inflammation (e.g., in rheumatoid arthritis, Crohn’s disease) leads
to prolonged cytokine release and immune cell infiltration, causing tissue destruction.
19. How do mast cells contribute to allergic reactions?
Answer: By releasing histamine and other inflammatory mediators upon IgE activation.
Explanation: Mast cell degranulation in response to allergens leads to symptoms such as
swelling, itching, and anaphylaxis.
20. What is the function of dendritic cells in immunity?
Answer: To capture, process, and present antigens to T cells.
Explanation: Dendritic cells act as professional antigen-presenting cells (APCs) that
initiate adaptive immune responses.
21. What is immune surveillance?
Answer: The ability of the immune system to detect and eliminate cancerous or infected
cells.
