An immune response to polysaccharide subunit vaccines can be obtained

Correct Answer: D

Rationale: The correct answer is D because coupling the polysaccharide subunit to a protein carrier enhances the immune response by converting the T-independent response to a T-dependent response. This allows for the induction of memory B cells and long-lasting immunity. Adjuvants (choice A) may enhance immune response but are not essential for polysaccharide-protein conjugate vaccines. Multiple booster injections (choice B) are not required for polysaccharide-protein conjugate vaccines as a single dose can induce a robust immune response. Administering orally (choice C) is not the only route for obtaining an immune response to polysaccharide subunit vaccines.

Correct Answer: A

Rationale: The correct answer is A because the meeting of naïve T cells and dendritic cells is not facilitated by the presence of naïve B cells. Naïve T cells interact with dendritic cells in the paracortex of lymph nodes, not with naïve B cells. The movement of T cells along connective tissue networks aids in their interaction with dendritic cells, and this interaction may supply the T cell with activation Signal 1, which is essential for T cell activation. Overall, the incorrect choices (B, C, and D) are actually true statements regarding the meeting of naïve T cells and dendritic cells, making them incorrect options.

Correct Answer: B

Rationale: The correct answer is B because Ehrlich proposed that each cell producing antibodies would express several receptors, each specific for different antigens, whereas Burnet proposed that each single antibody-producing cell expresses only one type of receptor. This is the main difference between the two theories. Ehrlich's concept of multiple receptors per cell allows for a broader range of specificity and diversity in the immune response. The other choices are incorrect because they do not directly address the main difference between the two theories as outlined above. Choice A is incorrect because both Ehrlich and Burnet emphasized the importance of specificity, but they differed in their views on receptor diversity per cell. Choice C is incorrect because it focuses on the identity of soluble antibodies and receptors, which is not the main differentiator between the two theories. Choice D is incorrect as it mentions the release of soluble antigen receptors, which is not the main point of differentiation between Ehrlich and Burnet's theories.

Correct Answer: C

Rationale: The correct answer is C: ROS (Reactive Oxygen Species) is not a PAMP (Pathogen-Associated Molecular Pattern) because it is not a specific molecular pattern derived from pathogens. PAMPs are recognized by the innate immune system to trigger an immune response. Viral dsRNA, peptidoglycan, and flagellin are all examples of PAMPs as they are specific molecules commonly found in pathogens that can be recognized by pattern recognition receptors (PRRs) on immune cells, leading to activation of the immune response.ROS, on the other hand, are reactive molecules produced by host cells in response to pathogens but are not specific molecular patterns derived from pathogens. Therefore, ROS is not considered a PAMP.

Correct Answer: B

Rationale: Step 1: Acute-phase proteins are a group of proteins produced by the liver in response to inflammation or infection. Step 2: Mannose binding lectin (MBL) is an acute-phase protein that plays a role in the innate immune response. Step 3: MBL binds to pathogens and activates the complement system to enhance immune responses. Step 4: Selectins are cell adhesion molecules, not acute-phase proteins. Step 5: Lysozyme is an enzyme that destroys bacterial cell walls, not typically classified as an acute-phase protein. Step 6: Defensins are antimicrobial peptides, not typically classified as acute-phase proteins. Summary: MBL is the correct choice as it is a well-known acute-phase protein involved in the immune response. Selectins, Lysozyme, and Defensins are not typically classified as acute-phase proteins and are involved in different functions.