Nokea
A co-receptor on target cells for HIV is
- A. gp120
- B. CR4
- C. CR5
- D. CXCR4
Correct Answer: D
Rationale: The correct answer is D: CXCR4. CXCR4 is a chemokine receptor that serves as a co-receptor for HIV entry into target cells. Step 1: HIV binds to CD4 receptor on the target cell. Step 2: The viral envelope protein gp120 then interacts with either CXCR4 or CCR5 co-receptor to facilitate viral entry. Step 3: In the case of CXCR4-tropic HIV strains, CXCR4 is the co-receptor used for entry into the target cell. Therefore, choice D is correct. Choices A (gp120) and C (CR5) are incorrect as they are not co-receptors, while choice B (CR4) is not a known co-receptor for HIV entry.
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The release of IL-8 at an infection site specifically induces
- A. Increase of adhesion molecules on local endothelial cells
- B. Local recruitment of neutrophils
- C. Systemic effects, including fever
- D. Increase of acute-phase proteins
Correct Answer: B
Rationale: The correct answer is B because IL-8 is a chemokine that specifically functions to recruit neutrophils to the site of infection. Neutrophils are crucial for fighting off pathogens. A: Increase of adhesion molecules on local endothelial cells is not directly induced by IL-8. C: Systemic effects, including fever, are typically mediated by other cytokines like IL-1 and IL-6. D: Increase of acute-phase proteins is not the primary role of IL-8 in the immune response.
What do pattern recognition receptors (PRRs) identify?
- A. Specific antigens
- B. Pathogen-associated molecular patterns (PAMPs)
- C. Host self-proteins
- D. Specific viruses only
Correct Answer: B
Rationale: Pattern recognition receptors (PRRs) identify Pathogen-associated molecular patterns (PAMPs) because PAMPs are unique molecules found on pathogens that trigger an immune response. PRRs recognize these patterns to distinguish between self and non-self. This recognition is crucial for initiating an immune response against potential threats. Specific antigens (A) and specific viruses only (D) are too narrow in scope as PRRs are designed to detect a wide range of patterns. Host self-proteins (C) are recognized by other mechanisms in the immune system to prevent autoimmunity.
What is the lag phase of the primary antibody response?
- A. 1-3 days
- B. 5-10 days
- C. 10-15 days
- D. No lag phase
Correct Answer: B
Rationale: The lag phase of the primary antibody response refers to the time it takes for the immune system to generate specific antibodies after initial exposure to an antigen. The correct answer is B (5-10 days) because during this period, B cells are activated, undergo proliferation, differentiate into plasma cells, and start producing antibodies. This process takes time as the immune system needs to recognize the antigen, mount a response, and produce sufficient antibodies. Option A (1-3 days) is too short for the full activation and differentiation of B cells. Option C (10-15 days) is too long for the typical lag phase duration. Option D (No lag phase) is incorrect because there is always a lag phase before the peak antibody production in the primary immune response.
Antihistamines are used cautiously in older men with prostatic hypertrophy for which of the following reasons?
- A. Because these clients may experience increased drowsiness
- B. Because these clients may experience difficulty voiding
- C. Because these clients face a greater risk of cardiac arrest
- D. Because these clients have a lower autoimmune response
Correct Answer: B
Rationale: Antihistamines can cause urinary retention which is particularly problematic for older men with prostatic hypertrophy.
What chemical in poison ivy is responsible for triggering contact dermatitis?
- A. Histamine
- B. Urushiol oil
- C. Lipopolysaccharide (LPS)
- D. C3a
Correct Answer: B
Rationale: The correct answer is B: Urushiol oil. Urushiol oil is the allergen in poison ivy that triggers contact dermatitis. When urushiol oil comes into contact with the skin, it can cause an allergic reaction leading to redness, itching, and inflammation. Histamine (choice A) is a compound released by the body in response to allergens but is not the specific chemical in poison ivy. Lipopolysaccharide (LPS) (choice C) is a component of the outer membrane of certain bacteria and not present in poison ivy. C3a (choice D) is a complement protein involved in the immune response but not related to poison ivy dermatitis.