Which one of the following properties of antibodies is NOT dependent on the structure of the heavy-chain constant region?

Correct Answer: D

Rationale: The correct answer is D. The affinity for antigen is determined by the variable region of the antibody, specifically the antigen-binding site. The heavy-chain constant region influences the other properties listed. A: The ability to cross the placenta is determined by the structure of the heavy-chain constant region, particularly the Fc region. B: Isotype (class) is determined by the type of heavy-chain constant region present in the antibody. C: The ability to fix complement is also influenced by the heavy-chain constant region, particularly the Fc region. Therefore, D is the only property that is not dependent on the structure of the heavy-chain constant region.

Correct Answer: D

Rationale: The correct answer is D because allotypes are indeed due to genetic polymorphism within a species. Allotypes are genetic variants of immunoglobulins, resulting from differences in amino acid sequences. This genetic diversity within a species allows for variability in the immune response. Choices A, B, and C are incorrect. Allotypes can be found on both heavy and light chains, they are not determined by class I MHC genes, and they are not confined to the variable regions.

Correct Answer: B

Rationale: Step 1: When an individual receives a vaccination containing a weakened pathogen, the immune system recognizes it as foreign. Step 2: The immune system then mounts a response by producing antibodies specific to that pathogen. Step 3: These antibodies help the body recognize and fight the pathogen if encountered in the future. Step 4: Therefore, the ability to fight disease caused by the specific pathogen will increase due to antibody production. Summary: Choice B is correct because the primary purpose of vaccination is to stimulate antibody production specific to the pathogen, enhancing the body's ability to fight that particular disease. Choices A, C, and D are incorrect as they do not accurately reflect the immune response to vaccination containing a weakened pathogen.

Correct Answer: C

Rationale: The correct answer is C: Identify if a client has been infected with Mycobacterium tuberculosis. Rationale: 1. The Mantoux skin test using purified protein derivative (PPD) is a diagnostic tool to determine if an individual has been infected with the tuberculosis bacterium. 2. The test involves injecting a small amount of PPD under the skin and observing the reaction within 48-72 hours. 3. A positive reaction indicates exposure to the tuberculosis bacterium at some point in the past, not necessarily active infection. 4. It does not provide immunity against tuberculosis (Choice B) as it is a diagnostic, not a preventive measure. 5. It does not decrease hypersensitivity to PPD (Choice A) but rather elicits a specific immune response to detect prior exposure. 6. It does not detect active tuberculosis infection immediately (Choice D) but rather indicates past exposure, requiring further testing for active disease. In summary, the Mantoux skin test with PPD is used

Correct Answer: B

Rationale: Step 1: Exercise is the correct answer. Regular exercise is beneficial for individuals with SLE as it can help improve aerobic capacity and immune function, which can help manage the condition. Therefore, it is important for the client to work with her provider to develop an appropriate exercise program. Step 2: Pregnancy (choice A) can exacerbate SLE due to hormonal changes, leading to increased risk of renal and cardiovascular effects. Sunlight exposure (choice C) can trigger flare-ups in some individuals with SLE. Emotional stress (choice D) can also worsen SLE symptoms by affecting the immune system. Summary: Choice A is incorrect because pregnancy can exacerbate SLE due to hormonal changes. Choice C is incorrect because sunlight exposure can trigger flare-ups in some individuals with SLE. Choice D is incorrect because emotional stress can also worsen SLE symptoms.