Tolerogenic dendritic cells

Correct Answer: E

Rationale: In the context of the immune system, tolerogenic dendritic cells play a crucial role in maintaining immune tolerance by promoting T cell unresponsiveness, which is why option A, "Induce T cell unresponsiveness," is the correct answer. Tolerogenic dendritic cells achieve this by presenting antigens without providing the necessary co-stimulatory signals required for T cell activation. Option B, "Do not secrete IL-12," is incorrect because tolerogenic dendritic cells indeed do not secrete pro-inflammatory cytokines like IL-12, contributing to their tolerogenic function. Option C, "Express high levels of co-stimulatory molecules," is also incorrect as tolerogenic dendritic cells express low levels of co-stimulatory molecules, which is necessary for promoting tolerance instead of activating T cells. Option D, "Have recognized PAMPs," is incorrect because PAMPs (Pathogen-Associated Molecular Patterns) are typically associated with activating dendritic cells rather than tolerogenic dendritic cells, which are involved in immune tolerance. Understanding the function and characteristics of tolerogenic dendritic cells is crucial in comprehending immune regulation and tolerance mechanisms in the body.

Correct Answer: C

Rationale: The correct answer is C because NLRs are not important for embryonic development in Drosophila. NLRs are primarily involved in immune responses by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) in the cytosol. Choice A is correct as NLRs are indeed cytosolic receptors for MAMPs and DAMPs. Choice B is correct as NOD receptors are a subset of NLRs. Choice D is correct as similar proteins to NLRs are also found in plants, known as NBS-LRR proteins. Therefore, the incorrect statement is C, as NLRs are not essential for embryonic development in Drosophila.

Correct Answer: D

Rationale: The correct answer is D because a lower number of gut bacteria is not associated with obesity. In fact, research shows that an imbalance in gut bacteria, not a lower number, can contribute to obesity. Choice A is correct as there are indeed more bacteria in the gut than human cells in the body. Choice B is also correct as babies develop their commensal flora after birth. Choice C is correct, as studies on germ-free mice have shown the importance of microbiota in immune system development.

Correct Answer: B

Rationale: The correct answer is B because the 2009 H1N1 pandemic was caused by a newly assorted virus unrelated to existing human strains. This is atypical as typical pandemics are caused by animal strains. Option A is incorrect because the 2009 H1N1 pandemic did not emerge entirely as an assortment of human strains. Option C is incorrect as the 2009 H1N1 virus was not a variant of the 1918 H1N1 strain circulating in pigs. Option D is incorrect because the 2009 H1N1 pandemic did affect individuals across all age groups, including the very young.

Correct Answer: C

Rationale: The correct answer is C because a B cell epitope is not a part of the antibody molecule that contacts an antigen. B cell epitopes are specific regions on an antigen that bind to B cell receptors. Choice A is incorrect because denaturation can expose B cell epitopes. Choice B is incorrect because pathogens typically have multiple B cell epitopes. Choice D is incorrect because B cell epitopes can be found on various parts of pathogens, not just on the surface.