A plasma cell is a type of white blood cell that plays a crucial role in the immune system. These cells are derived from B cells, which are activated in response to an infection or foreign substance. Plasma cells produce large quantities of antibodies, proteins that help identify and neutralize pathogens like bacteria and viruses. Once formed, plasma cells can live for several days to months, continuously secreting antibodies into the bloodstream. This process helps the body remember past infections, providing long-term immunity. If the same pathogen invades again, the immune system can respond more quickly and effectively, thanks to the antibodies produced by plasma cells.