Which cell type is part of adaptive immunity and responsible for high-affinity antibody production upon re-exposure?

• A. B cells
• B. NK cells
• C. Macrophages
• D. Dendritic cells

Answer: (A)

Antibodies are produced by B cells, which are central to adaptive immunity. When B cells first encounter an antigen, they can differentiate into plasma cells that secrete antibodies and into memory B cells that persist for future responses. Through affinity maturation in germinal centers, the antibodies produced later have higher affinity. Upon re-exposure, memory B cells rapidly become plasma cells again, generating high-affinity antibodies quickly and more effectively. The other cell types—natural killer cells, macrophages, and dendritic cells—play roles in innate immunity or antigen presentation, but they do not produce antibodies, especially not high-affinity antibodies after re-exposure.