Which of the following is a feature of an adaptive immune response

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: 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.

Correct Answer: C

Rationale: The correct answer is C: TNF-alpha and TNF-beta. Tumor necrosis factors (TNF) are a specific category of cytokines known for their role in promoting inflammation and inducing cell death in tumor cells. TNF-alpha and TNF-beta are two key members of this cytokine category. Interleukins (choice A) are a different group of cytokines involved in immune responses. Interferons (choice B) are cytokines that help regulate the immune system's response to viral infections. TGF-beta (choice D) is a cytokine involved in regulating cell growth and differentiation, but not specifically associated with tumor necrosis factors.

Correct Answer: C

Rationale: The correct answer is C because Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) on pathogens, initiating the immune response. This recognition triggers the production of cytokines and chemokines, leading to inflammation and activation of immune cells. Choice A is incorrect because TLRs do not identify self-antigens but rather foreign antigens. Choice B is incorrect as TLRs do not directly mediate phagocytosis but rather initiate signaling pathways that lead to phagocytosis by immune cells. Choice D is incorrect because TLRs do not suppress cytokine secretion; rather, they stimulate cytokine production.