Which cytokine group is most commonly associated with antiviral responses?

Correct Answer: B

Rationale: Interferons are the correct answer as they are a cytokine group primarily associated with antiviral responses. They play a key role in the immune response against viral infections by inhibiting viral replication and spreading to other cells. Interleukins are more diverse and involved in various immune responses, not specifically antiviral. Tumor necrosis factors are more related to inflammation and cell death. Transforming growth factors are involved in cell growth and differentiation, not primarily antiviral responses. Therefore, B: Interferons is the most appropriate choice for cytokine group associated with antiviral responses.

Correct Answer: B

Rationale: The correct answer to the question, "Which of the following complement components is an opsonin?" is B) C3b. Rationale: C3b functions as an opsonin by binding to pathogens and marking them for phagocytosis by immune cells. Opsonins enhance the process of phagocytosis by facilitating the recognition and ingestion of pathogens by immune cells. Incorrect options: A) C3a: C3a is involved in inflammation and recruitment of immune cells, but it is not an opsonin. C) C4a: C4a is also involved in inflammation but does not act as an opsonin. D) C5a: C5a is a potent inflammatory mediator but is not an opsonin. Educational context: Understanding the role of complement components in the immune system is crucial for comprehending how the body defends itself against pathogens. Knowing the specific functions of complement proteins like C3b helps students grasp the intricacies of immune responses and how various components work together to protect the body from infections.

Correct Answer: B

Rationale: The correct answer is B (C3a, C4a, and C5a) because these complement components are known as anaphylatoxins that mediate inflammation by inducing vasodilation, increasing vascular permeability, and recruiting immune cells. C3b (choice A) is involved in opsonization, not inflammation. C5b (choice C) is part of the membrane attack complex for cell lysis. C1q (choice D) initiates the classical complement pathway, but it does not directly mediate inflammation.

Correct Answer: C

Rationale: Step 1: Innate immunity is the body's first line of defense against pathogens. Step 2: Physical defenses include barriers like skin and mucous membranes. Step 3: Cellular defenses include immune cells like macrophages and natural killer cells. Step 4: These defenses are present from birth and do not require prior exposure to pathogens. Step 5: Choice C is true as innate immunity encompasses both physical and cellular defenses, making it the correct answer. Other choices are incorrect: A: Innate immunity does play a role in stimulating adaptive immunity through antigen presentation. B: It does not require prior exposure to function, as it is a rapid and non-specific response. D: Innate immunity is not antigen-specific; adaptive immunity is responsible for antigen-specific responses.

Correct Answer: B

Rationale: Granzyme entering a target cell activates apoptosis pathways by inducing cell death. Firstly, granzyme activates caspases leading to cell death. Secondly, it triggers DNA fragmentation and cell shrinkage. Lastly, it enhances membrane blebbing and apoptotic body formation. The other choices are incorrect because granzyme does not neutralize toxins, inhibit cytokine secretion, or promote antigen presentation within a target cell.