Which statement indicates that the patient needs further instruction about application of ice to a sprain?

Correct Answer: B

Rationale: The correct answer is B because keeping ice on the knee for the rest of the day can lead to skin damage or frostbite. Choice A is correct as it acknowledges the purpose of ice in reducing swelling. Choice C shows understanding of using ice as directed. Choice D indicates proper understanding of combining elevation with ice for swelling reduction.

Correct Answer: C

Rationale: The correct answer is C because an adaptive immune response induces memory of previously encountered antigens. This memory allows the immune system to respond more rapidly and effectively upon subsequent exposures to the same antigen. This feature is crucial for long-term immunity. Option A is incorrect since adaptive immune responses typically take days to develop. Option B is incorrect as not all multicellular organisms possess adaptive immunity. Option D is incorrect because immune tolerance mechanisms can sometimes fail, leading to autoimmune disorders where self is not distinguished from non-self.

Correct Answer: A

Rationale: The correct answer is A: HEV (High Endothelial Venules). PNAd is a ligand expressed on high endothelial venules, which helps in the recruitment of lymphocytes from the bloodstream into secondary lymphoid organs. PNAd is not primarily expressed on lymphocytes themselves (B) or dendritic cells (C). While PNAd can be involved in thymocyte migration to the thymus, it is not expressed on the thymus itself (D). Thus, the correct answer is A as it directly relates to the function and location of PNAd expression.

Correct Answer: C

Rationale: Step-by-step rationale for why choice C (Anti-TNF-α) is correct: 1. Anti-TNF-α drugs target specific molecules involved in autoimmune responses. 2. By inhibiting TNF-α, these drugs reduce inflammation and slow disease progression. 3. This makes them disease-modifying, as they alter the course of the autoimmune disease. Summary of why other choices are incorrect: A: Corticosteroids are anti-inflammatory but not disease-modifying in autoimmune diseases. B: Aspirin is primarily used for pain relief and reducing inflammation, not modifying the disease. D: C-cell depleting agents are not commonly used for autoimmune diseases and do not target TNF-α.

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.