Nokea
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.
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Which of the following is not a systemic cytokine?
- A. TNF
- B. IL-1
- C. IL-6
- D. IL-8
Correct Answer: D
Rationale: The correct answer is D: IL-8. IL-8 is not a systemic cytokine because it mainly acts locally at the site of inflammation to recruit neutrophils. Systemic cytokines like TNF, IL-1, and IL-6 have widespread effects throughout the body, influencing various immune responses and inflammatory processes. IL-8's localized action distinguishes it from systemic cytokines, making it the correct choice. TNF, IL-1, and IL-6 are all systemic cytokines that play key roles in regulating the immune response and inflammation at a systemic level, unlike IL-8.
What is the diversity of pattern recognition receptors (PRRs) like?
- A. Highly diverse due to somatic recombination
- B. Limited because they are germline-encoded
- C. Constantly changing in response to infections
- D. Specific to individual antigens
Correct Answer: B
Rationale: The correct answer is B because pattern recognition receptors (PRRs) are encoded in the germline, meaning they are genetically determined and do not change during an individual's lifetime. This ensures consistency in detecting various pathogens across different individuals. Choices A, C, and D are incorrect because PRR diversity is not influenced by somatic recombination, does not change constantly in response to infections, and is not specific to individual antigens.
What disease is associated with autoantibodies binding to type IV collagen?
- A. Sarcoidosis
- B. Goodpasture's syndrome
- C. Systemic lupus erythematosus (SLE)
- D. Rheumatoid arthritis
Correct Answer: B
Rationale: The correct answer is B: Goodpasture's syndrome. This disease is specifically associated with autoantibodies targeting type IV collagen in the basement membranes of the kidneys and lungs, leading to glomerulonephritis and pulmonary hemorrhage. Sarcoidosis (A) involves non-caseating granulomas, not collagen autoantibodies. Systemic lupus erythematosus (SLE) (C) is associated with various autoantibodies but not specifically targeting type IV collagen. Rheumatoid arthritis (D) is characterized by autoantibodies against citrullinated peptides and synovial tissue, not type IV collagen.
Which type of immunity is the result of contact with the antigen through infection and is the longest lasting type of immunity?
- A. Active innate immunity
- B. Passive innate immunity
- C. Active acquired immunity
- D. Passive acquired immunity
Correct Answer: C
Rationale: Active acquired immunity results from direct exposure to an antigen, such as through infection or vaccination. It involves the body's immune system recognizing and remembering the antigen, leading to long-lasting immunity.
A patient’s breast tumor originates from embryonal ectoderm. It has moderate dysplasia and moderately differentiated cells. It is a small tumor with minimal lymph node involvement and no metastases. What is the best description of this tumor?
- A. Sarcoma,grade II,T3 N4 M0
- B. Leukemia,grade I,T1 N2 M1
- C. Carcinoma,grade II,T1 N1 M0
- D. Lymphoma,grade III,T1 N0 M
Correct Answer: C
Rationale: This tumor is classified as a carcinoma, grade II, with a small size, limited lymph node involvement, and no metastases.