What is the role of memory cells in immunity?

• A. Memory cells are produced only during natural infection and not vaccination.
• B. Memory B- and T-cells persist after infection or vaccination to enable a faster, stronger response upon re-exposure.
• C. Memory cells produce antibodies immediately but do not respond to re-exposure.
• D. Memory cells are a form of innate immune cells that activate gradually.

Answer: (B)

Memory B- and T-cells are long-lived players of the adaptive immune system. After an infection or vaccination, these cells persist so that if the same pathogen appears again, they can respond much more quickly and effectively.

When re-exposure happens, memory B cells rapidly differentiate into antibody-secreting cells and produce high-affinity antibodies, while memory T cells quickly proliferate and become helper or cytotoxic cells to coordinate and execute a strong immune attack. This results in a faster, stronger, and more targeted response that often neutralizes the pathogen before it can cause disease.

Vaccines are designed to generate these memory cells, so you’re better protected without needing to experience the illness itself. In contrast, the other statements aren’t accurate: memory cells aren’t limited to natural infection and can be generated by vaccines; they do respond to re-exposure and help clear infections; and they are part of adaptive immunity, not innate.