The nurse is studying hypersensitivity reactions. Which reactions are correctly matched with their hypersensitivity types? (Select one that does not apply.)

Correct Answer: B

Rationale: The correct answer is B because Type II hypersensitivity reactions are mediated by the action of immunoglobulin G (IgG) or immunoglobulin M (IgM), not just IgM alone. IgG or IgM antibodies target specific antigens on the surface of cells or tissues, leading to cell destruction. In contrast, Type I hypersensitivity reactions (choice A) involve immediate IgE-mediated responses to allergens like hay fever and anaphylaxis. Type III reactions (choice C) are characterized by immune complex deposition in tissues, not blood vessel walls. Type IV reactions (choice D) are delayed hypersensitivity reactions involving T cell-mediated responses, such as poison ivy contact dermatitis and transplant rejection.

Correct Answer: A

Rationale: The correct answer is A (90%). Negative selection in the thymus eliminates self-reactive T cells. The process ensures self-tolerance. The majority of developing thymocytes are removed during negative selection, making it close to 90%. Choices B, C, and D are incorrect because negative selection eliminates a high percentage of thymocytes, not a lower percentage as indicated in those options.

Correct Answer: C

Rationale: The correct answer is C because the release of newly formed virus from the infected cell is actually mediated by Neuraminidase (NA), not Hemagglutinin (HA). 1. Influenza virus is indeed an RNA virus (Choice A). 2. In humans, influenza primarily infects lung epithelial cells (Choice B). 3. Hemagglutinin (HA) helps the virus enter host cells, while Neuraminidase (NA) helps release viral particles from infected cells (Choice C is incorrect). 4. Tamiflu is a Neuraminidase (NA) inhibitor, which prevents the release of viral particles, aiding in the treatment of influenza infections (Choice D).

Correct Answer: D

Rationale: Step-by-step rationale: 1. NOD2 is a cytosolic receptor for bacteria, detecting bacterial molecules. 2. Mutations in NOD2 are found in 30% of patients with Crohn's disease. 3. NOD2 activation triggers NFκB signaling pathway. 4. Therefore, all the statements (A, B, C) are correct, making option D the correct answer. Other choices are incorrect as they do not encompass all the correct statements about NOD2.

Correct Answer: C

Rationale: The correct answer is C: Low antibiotic use. The hygiene hypothesis suggests that reduced exposure to infections, which can happen with low antibiotic use, can lead to an increased risk of immune diseases. Antibiotics can disrupt the balance of gut microbiota, which plays a crucial role in immune system development. A: Small family size may not necessarily protect against immune diseases as it does not directly relate to exposure to infections. B: Good sanitation can reduce the spread of infections but may not necessarily protect against immune diseases. D: Living in "westernized" countries is a broad factor and does not directly address the impact of low antibiotic use on immune diseases.