What distinguishes adaptive immunity from innate immunity?

Correct Answer: B

Rationale: The correct answer is B because adaptive immunity involves memory, meaning the immune system can recognize and respond more effectively to specific antigens upon subsequent exposure. This high antigen specificity allows for tailored responses to different pathogens. In contrast, innate immunity lacks memory and specificity, providing only a rapid but non-specific response to a wide range of pathogens. Choices A, C, and D are incorrect because they do not adequately capture the key distinguishing features of adaptive immunity.

Correct Answer: B

Rationale: The correct answer is B: Cell-mediated immunity. T lymphocytes are a type of white blood cell that plays a critical role in cell-mediated immunity by directly attacking infected cells and coordinating the immune response. This type of immunity is essential for fighting intracellular pathogens such as viruses and certain bacteria. A: Humoral immunity is mediated by B cells and involves the production of antibodies to neutralize pathogens. T lymphocytes do not directly participate in humoral immunity. C: Passive immunity is acquired through the transfer of antibodies from one individual to another, providing immediate protection. T lymphocytes are not involved in passive immunity. D: Innate immunity is the body's first line of defense against pathogens and does not involve T lymphocytes, which are part of the adaptive immune response.

Correct Answer: B

Rationale: The correct answer is B because Type V hypersensitivity involves antibodies stimulating receptors instead of destroying them. In Type II hypersensitivity, antibodies target antigens on cell surfaces, leading to cell destruction. In Type V, antibodies bind to cell receptors, causing abnormal receptor activation. Choices A, C, and D are incorrect because Type V hypersensitivity is not mediated by T cells (A), does not involve immune complex formation (C), and does involve the immune system (D). Therefore, the unique characteristic of Type V hypersensitivity is the stimulation of receptors by antibodies, making choice B the correct answer.

Correct Answer: B

Rationale: The correct answer is B: Systemic release of vasoactive mediators. Anaphylaxis is a severe allergic reaction that is primarily caused by the systemic release of vasoactive mediators such as histamine, prostaglandins, and leukotrienes from mast cells and basophils. These mediators lead to widespread vasodilation, increased vascular permeability, bronchoconstriction, and systemic hypotension, resulting in the characteristic symptoms of anaphylaxis. Choice A (Immune complex deposition) is incorrect because anaphylaxis is not caused by the deposition of immune complexes but rather by the immediate hypersensitivity reaction. Choice C (Localized mast cell degranulation) is incorrect because anaphylaxis involves systemic mast cell degranulation leading to widespread effects throughout the body, not just localized reactions. Choice D (T cell activation) is incorrect because anaphylaxis is primarily mediated by IgE antibodies and mast cells, not T cells.

Correct Answer: B

Rationale: The correct answer is B: Glomerular basement membrane. In SLE, immune complexes deposit in various tissues, leading to inflammation and damage. The glomerular basement membrane is a common site for immune complex deposition in SLE, resulting in lupus nephritis. The other choices are incorrect because immune complex deposition does not typically occur in the thyroid, peripheral nerves, or mast cells in SLE. Thyroid involvement in SLE is more related to autoimmune thyroiditis, while peripheral nerves are not a major site for immune complex deposition in this condition. Mast cells are primarily involved in allergic reactions and are not a major target in SLE.