Which of the following statements is FALSE about memory cells?

The statement regarding memory cells being created only during the first exposure to an antigen is false. Memory cells are specifically formed during the adaptive immune response, which typically occurs after the first exposure to an antigen. However, they are not limited to just the initial encounter with an antigen; they can also be generated during subsequent exposures as the immune system becomes more efficient over time.

When the immune system first encounters a pathogen, specific B and T lymphocytes are activated, proliferating into effector cells that help eliminate the pathogen. Some of these activated cells then differentiate into memory cells, which are specifically designed to linger in the body long-term, providing a faster and more robust response to any future exposures to the same antigen.

In addition, memory cells can indeed enhance the immune response upon re-exposure, live for extended periods (sometimes for years or even a lifetime), and can differentiate into plasma cells that produce antibodies upon a second encounter with the antigen. Therefore, the assertion about their creation only during the first exposure is not accurate.