What is the lifelong function of memory B cells?

Memory B cells are a crucial component of the adaptive immune response, specifically in the context of humoral immunity. Their primary lifelong function is to provide a rapid and robust response upon re-exposure to a previously encountered antigen. When the immune system encounters an antigen for the first time, naive B cells are activated, proliferate, and differentiate into effector cells that secrete antibodies. Some of these activated B cells will become memory B cells.

The significance of memory B cells lies in their ability to recognize and respond rapidly to antigens they have encountered previously. Upon re-exposure to the same antigen, these cells are able to quickly differentiate into plasmablasts and plasma cells, which subsequently produce the appropriate antibodies at a much higher rate than during the primary immune response. This leads to a more effective and faster immune response, providing long-lasting immunity.

In contrast, the other options describe functions that are not associated with memory B cells. Secreting hormones pertains to different types of cells, primarily endocrine cells. Phagocytizing pathogens is a role typically associated with immune cells such as macrophages and neutrophils. Stimulating T-cell responses is mainly the function of antigen-presenting cells. Therefore, the role of producing antibodies upon re-exposure