Which antibody isotype is primarily involved in mucosal immunity?

Correct Answer: B

Rationale: The correct answer is B: IgA. IgA is primarily involved in mucosal immunity as it is the most abundant antibody present in mucosal secretions like saliva, tears, and breast milk. IgA plays a crucial role in preventing pathogens from entering the body through mucosal surfaces. IgG is more involved in systemic immunity, IgM is the first antibody produced in response to an infection, and IgE is associated with allergic reactions. Therefore, IgA is the most appropriate choice for mucosal immunity.

Correct Answer: C

Rationale: The correct answer is C: Systemic lupus erythematosus (SLE). In Type III hypersensitivity, immune complexes form and deposit in tissues, leading to inflammation and tissue damage. SLE is a classic example of a Type III hypersensitivity reaction where these immune complexes deposit in various organs causing systemic inflammation and damage. Graves's disease (A) is an example of Type II hypersensitivity, where autoantibodies target cell-surface receptors. Goodpasture's syndrome (B) is a Type II hypersensitivity disease affecting the kidneys and lungs. Contact dermatitis (D) is a Type IV hypersensitivity reaction mediated by T cells, not involving immune complexes. Therefore, the correct answer is C as it aligns with the characteristic disease associated with Type III hypersensitivity.

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: Sarcoidosis. Type IV hypersensitivity reactions are mediated by T cells and are characterized by delayed onset inflammatory responses. Sarcoidosis is a granulomatous disease where T cells form granulomas in affected tissues. Anaphylaxis (A) is a Type I hypersensitivity reaction involving IgE antibodies. Grave's disease (C) is an autoimmune disorder caused by Type II hypersensitivity reaction mediated by antibodies. Goodpasture's syndrome (D) is a Type II hypersensitivity reaction involving antibodies attacking basement membranes. Therefore, the correct answer is B as it fits the characteristics of a Type IV hypersensitivity reaction.

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.