Adaptive immunity is mediated by which type of cells?

• A. Macrophages
• B. Dendritic cells
• C. Neutrophils
• D. Lymphocytes

Answer: (D)

Adaptive immunity relies on lymphocytes—the B cells and T cells. These cells carry receptors that recognize specific antigens, enabling targeted responses. B cells can become plasma cells that produce antibodies, providing humoral immunity, while T cells mediate cell-dependent responses, with helpers coordinating the response and cytotoxic T cells destroying infected cells. A key feature is specificity plus memory: after initial exposure, lymphocytes expand clonally and form memory cells for a faster, stronger response upon re-exposure.

Other cells play supporting roles but aren’t the primary mediators of adaptive immunity. Macrophages and dendritic cells act as antigen-presenting cells to initiate the adaptive response, but the actual specificity and memory come from lymphocytes. Neutrophils are part of innate immunity and respond quickly in a non-specific way, without antigen-specific memory.