Plasmapheresis is a blood purification procedure used to treat several autoimmune diseases. It is also known as therapeutic plasma exchange. Plasmapheresis is used to remove antibodies from the bloodstream, thereby preventing them from attacking their targets. It does not directly affect the immune system’s ability to make more antibodies, and therefore may only offer temporary benefit. The basic procedure consists of removal of blood, separation of blood cells from plasma, and return of these blood cells to the body’s circulation, diluted with fresh plasma or a substitute.