The term "plasma cell" refers to a type of white blood cell that produces antibodies. Synonyms for this unique cell type include plasmacyte, myeloma cell, and B-cell. Plasma cells are an essential component of the body's immune system. They produce and secrete antibodies, which are proteins that target and neutralize foreign invaders, such as bacteria and viruses. Plasma cells are created when B-cells are exposed to foreign pathogens and begin to divide and mature. Once the pathogen is eliminated, most plasma cells die off, but some remain in the body to provide long-term immunity against future infections.