Which of the following is NOT true about the definition of acquired passive immunity

Correct Answer: E

Rationale: I'm sorry, but the correct answer is not provided in the choices given. Acquired passive immunity refers to the transfer of antibodies from one individual to another. Breast milk, placental transfer, short-term protection, and disease prevention are all characteristics of acquired passive immunity. Therefore, the correct answer is not presented in the options provided.

Correct Answer: B

Rationale: The correct answer is B because TLR4 is not a phagocytic receptor, but rather a pattern recognition receptor involved in recognizing pathogen-associated molecular patterns (PAMPs). A: Correct, TLR4 is expressed on dendritic cells and macrophages. C: Correct, TLR4 is expressed on the membrane in complex with MD2. D: Correct, mice resistant to endotoxic shock have a mutation in TLR4, indicating its role in the immune response to endotoxins.

Correct Answer: C

Rationale: The correct answer is C because inducing antibodies that can recognize the less variable regions of the Hemagglutinin (HA) protein across different strains allows for cross-protection against various flu strains. This approach is effective as it targets conserved regions of the virus, increasing the likelihood of providing broad immunity. Option A focuses on cytotoxic T cell response, which primarily targets infected cells and may not prevent viral entry into uninfected cells. Option B, on the other hand, is limited to highly strain-specific neutralizing antibodies, which may not provide adequate protection against evolving flu strains. Therefore, option C is the most effective in producing better flu vaccines by targeting less variable regions of HA for broader immunity.

Correct Answer: D

Rationale: The correct answer is D: Allowed to mature and enter the periphery. In this scenario, since the developing B cell has no binding affinity for self-antigens in the bone marrow, it will not undergo clonal deletion or anergy. Therefore, it will be allowed to mature and enter the periphery where it can encounter foreign antigens and participate in the immune response. Choices A and B are incorrect because clonal deletion and anergy are mechanisms used to eliminate or inactivate self-reactive B cells to prevent autoimmunity. Choice C is incorrect because a B cell without self-binding affinity is not a cause of autoimmunity in the periphery.

Correct Answer: B

Rationale: The correct answer is B, germline gene rearrangement. T cell receptor and B cell receptor genes both undergo germline gene rearrangement during lymphocyte development, where gene segments are rearranged to generate diverse antigen receptor specificities. Somatic hypermutation and isotype switching are processes specific to B cells in the adaptive immune response, not T cells. Therefore, choices A and C are incorrect. Choice D is incorrect as well since somatic hypermutation is not a process involved in T cell receptor gene rearrangement.