Nokea
What are the important functions of cell-mediated immunity (select all that apply)?
- A. Fungal infections
- B. Transfusion reactions
- C. Rejection of transplanted tissues
- D. Immunity against pathogens that survive outside cells
Correct Answer: A
Rationale: Cell-mediated immunity targets intracellular pathogens, such as viruses and fungi, and is critical in transplant rejection and certain hypersensitivity reactions.
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What is the key immune cell involved in granuloma formation?
- A. Mast cells
- B. Macrophages
- C. Neutrophils
- D. Dendritic cells
Correct Answer: B
Rationale: The correct answer is B: Macrophages. Macrophages are key immune cells involved in granuloma formation. They play a crucial role in engulfing and processing pathogens or foreign particles, leading to the formation of granulomas as part of the body's immune response. Mast cells (A) are primarily involved in allergic reactions. Neutrophils (C) are important in the initial immune response to infections but are not typically associated with granuloma formation. Dendritic cells (D) are important in antigen presentation and activation of T cells, but they are not the primary immune cells involved in granuloma formation.
To raise antibodies that interfere with the interaction of HIV with CD4+ T cells, vaccines should target which of the following HIV antigens
- A. gp41
- B. Reverse transcriptase
- C. gp120
- D. Matrix proteins
Correct Answer: C
Rationale: The correct answer is C: gp120. This is because gp120 is a key HIV antigen that plays a crucial role in binding to CD4 receptors on T cells, facilitating viral entry. By targeting gp120, vaccines can induce antibodies that block this interaction, preventing HIV from infecting CD4+ T cells. Conversely, choices A, B, and D (gp41, Reverse transcriptase, Matrix proteins) are not as effective targets for interfering with the CD4+ T cell interaction, as they do not directly impact the initial binding and entry process of HIV into the cells.
How do regulatory T cells (Tregs) maintain immune homeostasis?
- A. By killing infected cells
- B. By producing pro-inflammatory cytokines
- C. By suppressing immune responses using IL-10
- D. By activating macrophages
Correct Answer: C
Rationale: Regulatory T cells (Tregs) maintain immune homeostasis by suppressing immune responses using IL-10. Tregs release IL-10, which inhibits the activity of effector T cells and other immune cells, preventing excessive immune responses and maintaining balance. This mechanism helps prevent autoimmune diseases and chronic inflammation. Choices A, B, and D are incorrect because Tregs do not kill infected cells, produce pro-inflammatory cytokines, or activate macrophages. Instead, Tregs focus on regulating and dampening immune responses to maintain overall immune balance.
Normal mice injected with high doses of LPS die of septic shock. Mice resistant to LPS-induced septic shock have a mutation in which receptor?
- A. TLR4
- B. TLR5
- C. NOD1
- D. NOD2
Correct Answer: A
Rationale: Step 1: TLR4 is the receptor for lipopolysaccharide (LPS), a component of gram-negative bacteria.
Step 2: The question states that normal mice injected with high doses of LPS die, indicating TLR4 activation.
Step 3: Mutations in TLR4 can confer resistance to LPS-induced septic shock.
Step 4: Therefore, the correct answer is A: TLR4, as it is directly involved in recognizing LPS and triggering septic shock.
Summary: B: TLR5 does not specifically bind LPS. C: NOD1 and D: NOD2 are involved in intracellular recognition of bacterial components, not LPS.
Although the cause of autoimmune disorders is unknown, which factors are believed to be present in most conditions (select all that apply)?
- A. Younger age
- B. Male gender
- C. Inheritance of susceptibility genes
- D. Initiation of autoreactivity by triggers
Correct Answer: C
Rationale: Autoimmune disorders are often associated with genetic predisposition and environmental triggers that initiate autoreactivity.