The intestinal epithelial cells that specialize in the production of antimicrobial peptides are called:

Correct Answer: C

Rationale: The correct answer is C: Paneth cells. Paneth cells are specialized intestinal epithelial cells located in the small intestine that produce antimicrobial peptides to help defend against pathogens. They play a crucial role in maintaining gut homeostasis. Goblet cells (A) secrete mucus, enterocytes (B) absorb nutrients, and epithelial stem cells (D) are responsible for cell regeneration, but they do not produce antimicrobial peptides like Paneth cells do.

Correct Answer: D

Rationale: The correct answer is D because some top-selling drugs for immune-mediated diseases target either an inflammatory cytokine or its receptor. Monoclonal antibodies specific for an inflammatory cytokine can block its activity, while those targeting the receptor can prevent the cytokine from binding and triggering immune responses. Choices A and B are correct examples of drugs targeting inflammatory pathways. Choice C, targeting T cell lymphocytes, is less common for immune-mediated diseases compared to targeting cytokines or receptors. Therefore, D is the correct answer as it encompasses both common targeting strategies.

Correct Answer: B

Rationale: The correct order of events in naïve T cell activation is: antigen recognition, clonal expansion, entry into the site of infection. First, T cells must recognize the specific antigen presented by antigen-presenting cells. This recognition triggers clonal expansion, where T cells proliferate and differentiate into effector cells. Finally, the activated T cells migrate to the site of infection to combat the pathogen. Option B is correct because it follows this sequential order. Options A, C, and D are incorrect because they do not adhere to the correct sequence of events in naïve T cell activation.

Correct Answer: B

Rationale: Passive immunisation involves injecting preformed antibodies to provide immediate protection against microbes. This is suitable for quick immune response in infected individuals. Active immunisation, on the other hand, stimulates the body to produce its own antibodies over time, which is not ideal for immediate protection. Allergic immunisation is unrelated to providing antibodies. There is no immunisation type of "No such type of immunisation exist."

Correct Answer: C

Rationale: The correct answer is C: Natural killer cells. Natural killer cells are involved in cell-mediated immunity and have cytotoxic actions on tumor cells. They are part of the innate immune system and can directly kill infected or cancerous cells. Lysosomes (A) are organelles within cells that break down waste materials. Memory cells (B) are a type of immune cell that "remembers" previous infections to mount a faster response upon re-exposure. Histocompatibility cells (D) are involved in recognizing self from non-self in transplant situations, not in cytotoxic actions on tumor cells.