The nurse is assessing a client for signs and symptoms of systemic lupus erythematosus (SLE). Which of the following would be consistent with this disorder? (Select one that does not apply.)

Correct Answer: A

Rationale: The correct answer is A: Discoid rash on skin exposed to sunlight. Systemic lupus erythematosus (SLE) commonly presents with a characteristic butterfly-shaped rash on the face, especially over the cheeks and nose, that worsens with sunlight exposure. The rash is not limited to skin exposed to sunlight. Choices B, C, and D are inconsistent with SLE. B: Urinalysis negative for casts and protein is not indicative of SLE, as renal involvement in SLE often presents with the presence of casts and protein in the urine. C: Painful, deformed small joints is more typical of rheumatoid arthritis, not SLE. D: Pain on inspiration is a symptom of pleurisy, which can occur in SLE but is not a defining feature.

Correct Answer: B

Rationale: The correct answer is B: AIRE. APECED (Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy) is caused by mutations in the AIRE gene. AIRE is responsible for regulating the expression of self-antigens in the thymus, crucial for the development of immune tolerance. Deficiency in AIRE leads to the production of autoantibodies and autoimmune manifestations. Incorrect options: A: CTLA-4 is involved in downregulating immune responses but is not directly linked to APECED. C: Tregs (regulatory T cells) play a role in immune tolerance, but APECED is not directly caused by their deficiency. D: TGF-β is a cytokine involved in immune regulation, but its deficiency does not lead to APECED.

Correct Answer: D

Rationale: Step 1: Viral antigenic shift involves major changes in the surface proteins of the virus, particularly the hemagglutinin (HA) protein. Step 2: These changes result in the emergence of new variants that are not recognized by preexisting antibodies. Step 3: This process is distinct from antigenic drift, which involves minor changes due to random mutations. Step 4: Choice D correctly states that viral antigenic shift refers to the appearance of new HA variants not recognized by preexisting antibodies. Summary: Choice A is incorrect because viral antigenic shift is not caused by multiple random mutations. Choice B is incorrect as antigenic shift involves major changes, not a single mutation. Choice C is incorrect as it affects surface proteins like HA, not just internal proteins.

Correct Answer: A

Rationale: Defensins are cationic antimicrobial peptides that play a crucial role in the innate immune system by disrupting the microbial cell membrane. This property allows them to kill a wide range of pathogens. Option A is correct because it accurately describes the primary function of defensins. Option B, opsonins, are proteins that enhance phagocytosis but are not specific to defensins. Option C, DAMPs, are damage-associated molecular patterns released by damaged cells and are not related to defensins. Option D, fatty acids, are not directly related to the antimicrobial properties of defensins.

Correct Answer: B

Rationale: The correct answer is B: Membrane-disrupting peptides. Defensins are antimicrobial peptides that disrupt bacterial cell membranes. This disrupts the integrity of the bacterial cell, leading to cell lysis and death. Choice A is incorrect because mast cells release histamines, not defensins. Choice C is incorrect as acute phase proteins are involved in the immune response to inflammation. Choice D is incorrect as opsonins are molecules that enhance phagocytosis of pathogens by immune cells.