What are the effects of histamine released from mast cells?

Correct Answer: A

Rationale: The correct answer is A because histamine released from mast cells causes increased vascular permeability, leading to edema, and bronchoconstriction, contributing to respiratory symptoms. This is a key mechanism in allergic reactions. B: Neutralization of antigens and opsonization are functions of antibodies, not histamine. C: Complement activation and T cell proliferation are separate immune responses not mediated by histamine. D: Direct lysis of pathogens is typically carried out by immune cells like macrophages and natural killer cells, not histamine.

Correct Answer: B

Rationale: The correct answer is B. Baby powder is not recommended for individuals with systemic lupus erythematosus, as it can irritate the skin and worsen symptoms. A: Avoiding direct sunlight is crucial due to photosensitivity. C: Grouping errands helps conserve energy. D: Rest is important to manage fatigue. Summary: A, C, and D are all appropriate self-care measures for a client with systemic lupus erythematosus, while using baby powder is not recommended.

Correct Answer: A

Rationale: The correct answer is A: Germinal center. Germinal centers are specialized regions within lymph nodes where B cells undergo intense proliferation, somatic hypermutation, and class switching to generate high-affinity antibodies. This process is crucial for the adaptive immune response. Paracortex (B) contains T cells, not B cells. Medulla (C) is mainly involved in filtering lymph. Infected tissue (D) is not a specific site for B cell proliferation.

Correct Answer: B

Rationale: The correct answer is B: IL-2. IL-2 is essential for the clonal expansion of T cells as it promotes T cell proliferation. It is produced by activated T cells themselves and plays a crucial role in regulating immune responses. IL-1 is involved in inflammation, not T cell expansion. IL-4 is important for Th2 cell differentiation, while IL-5 is critical for eosinophil activation. In summary, IL-2 specifically promotes T cell clonal expansion, making it the correct choice in this context.

Correct Answer: D

Rationale: The correct answer is D because T regulatory cells are known to suppress immune responses and promote immune tolerance, which is opposite to causing immunity. Choice A is incorrect because T regulatory cells are indeed generated in the thymus upon expression of Foxp3. Choice B is incorrect as T regulatory cells can also be generated in the periphery in response to cytokines. Choice C is incorrect as T regulatory cells are known to inhibit effector T cells to regulate immune responses.