What distinguishes a memory cell from a plasma cell?

The distinction between memory cells and plasma cells is crucial for understanding the adaptive immune response. Memory cells are primarily responsible for long-term immunity. They are formed following exposure to an antigen and are capable of persisting for years, even decades, within the body. This longevity allows them to quickly respond to subsequent encounters with the same antigen, facilitating a faster and more robust immune response.

On the other hand, plasma cells are specialized B cells that are primarily tasked with the production and secretion of antibodies. When activated by an antigen, B cells differentiate into plasma cells, which then produce antibodies specific to that antigen. However, plasma cells have a relatively short lifespan and do not contribute to long-term immunity.

Understanding this distinction clarifies that while memory cells are essential for long-lasting immune protection by developing an immunological “memory,” plasma cells play a crucial but transient role in producing antibodies during an active immune response. This is why the choice indicating that memory cells are responsible for long-term immunity while plasma cells secrete antibodies accurately captures the essential functions of these two types of cells.