Final answer:
Plasma cells, which differentiate from B cells after antigen activation, are mainly found in the bone marrow where they function as antibody factories, producing antibodies to fight infections. These terminally differentiated cells are a crucial part of the immune system but ultimately have a limited lifespan.
Step-by-step explanation:
Plasma cells are specialized white blood cells that originate from B cells after their activation by an antigen. They are primarily found in the bone marrow, although they originate in secondary lymphoid organs. Following activation, plasma cells migrate back to the bone marrow, where they produce antibodies, which are Y-shaped proteins that bind specifically to antigens. Plasma cells are considered to be terminally differentiated, which means they are fully specialized and do not divide. Their main function is to act as antibody factories, secreting large quantities of a single type of antibody. After a period of intense antibody production, these plasma cells will eventually die off.
Antibodies produced by plasma cells are essential for the immune system to recognize and neutralize pathogens. The antibodies circulate through the bloodstream and the lymphatic system, helping to defend the body against infections. In addition to plasma cells, some activated B cells become long-lived memory cells, which can rapidly respond to a pathogen if it re-enters the body, contributing to long-term immunity.