Alumn is an adjuvant that triggers

Correct Answer: B

Rationale: The correct answer is B: DAMPs formation. Alum is known to trigger the release of damage-associated molecular patterns (DAMPs), which are endogenous molecules released by damaged cells. This activation of DAMPs plays a crucial role in initiating and enhancing the immune response. The other choices, TLR4, NOD1, and TLR9, are receptors involved in recognizing specific pathogen-associated molecular patterns (PAMPs) rather than DAMPs. Therefore, they are not directly triggered by alum. This makes choice B the correct answer based on the known mechanism of action of alum as an adjuvant.

Correct Answer: D

Rationale: The correct answer is D: Complement activation. Phagocytosis by macrophages involves engulfing and digesting pathogens. Complement activation occurs through a separate pathway involving a series of proteins that enhance the immune response. Phagocytosis does not directly lead to complement activation. Choices A, B, and C are outcomes of phagocytosis in macrophages: Respiratory burst involves production of reactive oxygen species, nitric oxide production helps destroy pathogens, and antigen presentation is important for activating other immune cells.

Correct Answer: D

Rationale: Passive immunization does not involve transferring naïve lymphocytes; instead, it transfers pre-formed antibodies for immediate protection. Choice D is incorrect because lymphocytes do not produce antibodies directly. Choices A, B, and C are correct: Passive immunization has been used for Ebola, transfers serum with antibodies, and provides immediate protection with pre-formed antibodies.

Correct Answer: D

Rationale: The Fc regions of antibodies interact with various immune cells and molecules to mediate effector functions. - A: Degranulation of mast cells: Fc receptors on mast cells bind to antibody Fc regions, triggering degranulation. - B: ADCC: Fc regions bind to Fc receptors on immune cells, facilitating target cell killing. - C: Complement activation: Antibody binding to antigens can activate the complement system via the Fc region. Therefore, the correct answer is D because the Fc regions of antibodies are involved in all mentioned effector functions.

Correct Answer: C

Rationale: The correct answer is C: Secondary lymphoid tissues. Naïve T cells are activated in secondary lymphoid tissues such as lymph nodes and spleen. These tissues are where T cells encounter antigen-presenting cells, receive co-stimulatory signals, and undergo clonal expansion to differentiate into effector T cells. Germinal centers are primarily for B cell responses. Primary lymphoid tissues (bone marrow and thymus) are where T cells mature but not where activation occurs. Choice D is incorrect as naïve T cell activation does occur in secondary lymphoid tissues.