Which immune response is characterized by memory B cells producing antibodies upon re-exposure?

The immune response characterized by memory B cells producing antibodies upon re-exposure is the secondary immune response. During the initial exposure to an antigen, the primary immune response occurs, where naïve B cells are activated to produce antibodies. However, this response is typically slower and less robust.

After the primary response, some of these activated B cells differentiate into memory B cells, which remain in the body long after the initial infection has been cleared. Upon subsequent exposures to the same antigen, these memory B cells can recognize it more quickly and efficiently. This leads to a faster and more intense production of antibodies, resulting in the secondary immune response.

In essence, the secondary immune response is pivotal for long-term immunity, allowing the body to respond more effectively to pathogens previously encountered. This mechanism underscores the importance of vaccines, which aim to create these memory B cells without causing disease.