What is the main function of memory B cells in the immune system?

Memory B cells play a crucial role in the immune system by providing long-term immunity against previously encountered pathogens. Their main function is to "remember" specific antigens associated with those pathogens. When the immune system encounters a pathogen for the first time, it generates a primary immune response, which includes the activation of B cells that differentiate into antibody-producing plasma cells. Some of these activated B cells then become memory B cells.

These memory B cells persist in the body long after the initial infection has resolved. If the same pathogen invades again, these memory B cells can quickly recognize the antigens, rapidly proliferate, and differentiate into plasma cells that produce specific antibodies against that pathogen. This secondary immune response is typically faster and more effective than the primary response, allowing the body to neutralize infections more efficiently.

The other options describe different functions or features of the immune response, but they do not specifically highlight the unique role of memory B cells in establishing long-term immunity. Immediate immune responses are primarily managed by other immune cells, and the direct destruction of infected cells is typically performed by cytotoxic T cells, not memory B cells. Therefore, the focus on long-term protection and recall of specific pathogens clearly defines the purpose of memory B cells in the immune system.